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

Abstract

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 are disclosed. The positive electrode active material includes first particles including a compound of chemical formula 1 and having an olivine structure, second particles including a compound of chemical formula 2 and having a spinel structure, and third particles including a compound of chemical formula 3 and having a layered structure. The amount of the third particles is about 10 parts by weight to about 50 parts by weight based on 100 parts by weight of the positive electrode active material. Chemical formula 1: Lia1Mnx1Fey1Az1PO4-c1, chemical formula 2: Lia2Mnx2By2O4-c2 and chemical formula 3: Lia3Nix3Coy3Mnz3Ew1O2-c3

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This U.S. nonprovisional patent application claims priority to Korean Patent Application No. 10-2024-0054513, filed on April 24, 2024, which is hereby incorporated by reference in its entirety. Technical Field

[0003] 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. More specifically, the present disclosure relates to a positive electrode active material including an olivine-based lithium compound, a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode active material. Background Art

[0004] With the rapid popularization of electronic devices using batteries (such as mobile phones, laptop computers, electric vehicles, etc.), the demand for rechargeable lithium batteries with high energy density and high capacity is rapidly increasing. Accordingly, research and development to improve the performance of rechargeable lithium batteries is being actively carried out.

[0005] Rechargeable lithium batteries consist of positive and negative electrodes (containing active materials capable of intercalating and deintercalating lithium ions) and an electrolyte. When lithium ions are intercalated and deintercalated into and from the positive and negative electrodes, rechargeable lithium batteries generate electricity through oxidation and reduction reactions. Summary of the Invention

[0006] The present disclosure provides a positive electrode active material that is economical and has high energy density, high average voltage, and excellent lifespan characteristics.

[0007] The present disclosure also provides a positive electrode that is economical and has high energy density, high average voltage, and excellent lifespan characteristics.

[0008] According to an embodiment of the present disclosure, the positive electrode active material may include first particles including a compound having an olivine structure of Chemical Formula 1, second particles including a compound having a spinel structure of Chemical Formula 2, and third particles including a compound having a layered structure of Chemical Formula 3. The amount of the third particles may be about 10 parts by weight to about 50 parts by weight based on 100 parts by weight of the positive electrode active material.

[0009] Chemical formula 1:

[0010] Li a1 Mn x1 Fe y1 A z1 PO 4-c1

[0011] In Chemical Formula 1, 0.8 < a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0.15 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.05, 0 ≤ c1 ≤ 0.05, x1 + y1 + z1 = 1, and A can be at least one of Al, Ti, V, and Mg.

[0012] Chemical Formula 2:

[0013] Li a2 Mn x2 B y2 O 4-c2

[0014] In Chemical Formula 2, 0.8 < a2 ≤ 1.2, 1.9 ≤ x2 ≤ 2.05, 0 ≤ y2 ≤ 0.05, 0 ≤ c2 ≤ 0.05, and B can be at least one of Al and Mg.

[0015] Chemical Formula 3:

[0016] Li a3 Ni x3 Co y3 Mn z3 E w1 O 2-c3

[0017] In Chemical Formula 3, 0.8 < a3 ≤ 1.2, 0.5 ≤ x3 ≤ 0.8, 0 ≤ y3 ≤ 0.10, 0.1 ≤ z3 ≤ 0.35, 0 ≤ w1 ≤ 0.1, 0 ≤ c3 ≤ 0.05, and E can be at least one of Al, Ti, Mg, Zr, Mo, and Nb.

[0018] According to another embodiment of the present disclosure, a positive electrode for a rechargeable lithium battery can 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 can include a positive electrode active material, a conductive material, and a binder. 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.

[0020] Figure 1 A simplified conceptual diagram of a rechargeable lithium battery according to some embodiments of the present disclosure is shown.

[0021] Figures 2 to 5 A rechargeable lithium battery according to embodiments is shown, wherein Figure 2 is a cylindrical battery, Figure 3 is a prismatic battery, and Figure 4 and Figure 5 is a pouch battery.

[0022] Figures 6 to 9 FIG. 1 is a schematic view showing a rechargeable lithium battery according to an embodiment of the present disclosure.

[0023] Figure 10A FIG. 2 is a scanning electron microscope (SEM) image showing a positive electrode active material according to an embodiment of the present disclosure.

[0024] Figure 10B FIG. 3 is a SEM image showing a positive electrode active material according to an embodiment of the present disclosure.

[0025] Figure 11 FIG. 4 is a SEM image showing a positive electrode active material according to an embodiment of the present disclosure.

[0026] Figure 12 FIG. 5 is a SEM image showing a positive electrode active material according to an embodiment of the present disclosure.

[0027] Figure 13 FIG. 6 is a SEM image showing a positive electrode active material according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0028] In order to fully understand the layout and effects of the present disclosure, some embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be noted that the present disclosure is not limited to the following exemplary embodiments, and can be implemented in various forms. Rather, the exemplary embodiments are provided only to disclose the present disclosure and to enable those skilled in the art to fully understand the scope of the present disclosure.

[0029] In the present description, when an element is referred to as being "on" another element, it can be directly on the other element, or an intervening element can be present therebetween. In the drawings, the size (e.g., thickness) of some components is exaggerated for effective explanation of the technical content. Throughout the specification, like reference numerals refer to like elements.

[0030] Unless specifically stated otherwise in the present description, expressions of a singular form can include expressions of a plural form. In addition, unless specifically stated otherwise, the phrase "A or B" can indicate "A but not B", "B but not A", and "both A and B". The terms "comprises" and / or "comprising", and / or "includes" and / or "including" used in the present description do not exclude the presence of one or more other components, or the addition of one or more other components.

[0031] As used herein, the term "combination thereof" can refer to a mixture, a stack, a composite, a copolymer, an alloy, a blend, or a reaction product.

[0032] The particle diameter can be an average particle diameter (i.e., average diameter) unless specifically limited otherwise in the present description. In addition, the particle diameter indicates an average diameter (D 50 ) at which the cumulative volume is about 50% by volume in a particle size distribution. The average diameter (D 50 ) can be measured by methods widely known to those skilled in the art, for example, by a particle size analyzer, a transmission electron microscope (TEM) image, or a scanning electron microscope (SEM) image. Alternatively, data analysis is performed using a dynamic light scattering measuring device, counting the number of particles for each particle size range, and then an average diameter (D 50 ) value can be obtained by calculation. As other methods, the average diameter (D 50 ) can be measured using a laser scattering method. In the laser scattering method, the target particles are dispersed in a dispersion solvent, introduced into a laser scattering particle diameter measuring device (for example, MT3000 commercially available from Microtrac, Inc.), and then irradiated with ultrasonic waves at 28 kHz at a power of 60 W. The average diameter (D 50 ) is calculated at a 50% particle diameter distribution reference in the measuring device.

[0033] Figure 1 is a cross-sectional view of a rechargeable lithium battery according to an embodiment of the disclosure. Referring to Figure 1 , the rechargeable lithium battery can include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0034] The positive electrode 10 and the negative electrode 20 can be spaced apart from each other by the separator 30. The separator 30 can be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 can be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20, and the separator 30 can be impregnated in the electrolyte ELL.

[0035] The electrolyte ELL can be a medium for transporting lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move toward the positive electrode 10 or the negative electrode 20 through the separator 30.

[0036] Positive electrode

[0037] The positive electrode 10 for the rechargeable lithium battery can 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 can include a positive electrode active material, and can further include a binder and / or a conductive material. The positive electrode active material layer AML1 according to an embodiment of the disclosure will be described below with reference to Figure 6 and Figure 7 . An aluminum foil can be used for the positive electrode current collector COL1, but the disclosure is not limited thereto.

[0038] Negative electrode

[0039] 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).

[0040] 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.

[0041] The binder can be used to adhere the negative electrode active material particles to each other, and also to adhere the negative electrode active material to the negative electrode current collector COL2. The binder can include a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0042] 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, or a combination thereof.

[0043] 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 a combination thereof.

[0044] 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.

[0045] The dry binder can be a polymer material capable of being fiberized. For example, the dry binder can be polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or a combination thereof.

[0046] The conductive material can be used to impart electrical conductivity to the electrode. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in a rechargeable lithium battery) and conducts electrons can be used in the battery. Non-limiting examples 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; a conductive polymer such as a polyphenylene derivative; or a mixture thereof.

[0047] 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, or a combination thereof.

[0048] Negative electrode active material

[0049] The negative electrode active material can include a material that reversibly intercalates / deintercalates lithium ions, a lithium metal, a lithium metal alloy, a material capable of doping / dedoping lithium, or a transition metal oxide.

[0050] 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, or a combination thereof. The crystalline carbon can be graphite such as amorphous, flaky, flaky, spherical, or fibrous natural graphite or artificial graphite. The amorphous carbon can be soft carbon, hard carbon, mesophase pitch carbonization product, calcined coke, or the like.

[0051] The lithium metal alloy includes an alloy of lithium with at least one metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0052] 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, or a combination thereof. In the Si-Q alloy, Q can be selected from 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, or a combination thereof. The Sn-based negative electrode active material can include Sn, SnO x (0 < x ≤ 2) (e.g., SnO2), a Sn-based alloy, or a combination thereof.

[0053] The silicon-carbon composite can be a composite of silicon and amorphous carbon. According to embodiments, the silicon-carbon composite 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 (core) in which primary silicon particles are aggregated and an amorphous carbon coating layer (shell) on the surface of the secondary particles. Amorphous carbon can also be provided 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.

[0054] 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 layer on the surface of the core.

[0055] 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.

[0056] Separator

[0057] According to the type 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 thin 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, or the like.

[0058] The separator 30 can include a porous substrate and a coating layer on one or both surfaces of the porous substrate, the coating layer including an organic material, an inorganic material, or a combination thereof.

[0059] The porous substrate can be a polymer film formed of any one polymer 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 (for example, ) or a copolymer or mixture of two or more thereof.

[0060] The organic material can include a polyvinylidene fluoride-based polymer or a (meth)acrylic-based polymer.

[0061] The inorganic material can include inorganic particles selected from the group consisting of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof, but is not limited to these examples.

[0062] The organic material and the inorganic material can be mixed in one coating layer, or coating layers including the organic material and coating layers including the inorganic material can be stacked.

[0063] Electrolyte

[0064] The electrolyte ELL for the rechargeable lithium battery can include a nonaqueous organic solvent and a lithium salt.

[0065] The nonaqueous organic solvent can be used as a medium for transporting ions participating in electrochemical reactions of the battery.

[0066] The nonaqueous 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, or a combination thereof.

[0067] The carbonate-based solvent can include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), or the like.

[0068] The ester-based solvent can include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanolide, mevalonolactone, valerolactone, caprolactone, or the like.

[0069] The ether-based solvent can include dibutyl ether, tetraglyme, diglyme, glyme, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, or the like. In addition, the ketone-based solvent can include cyclohexanone, or the like. The alcohol-based solvent can include ethanol, isopropyl alcohol, or the like, and the aprotic solvent can include nitriles (such as R-CN, where 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, or the like); amides (such as dimethylformamide); dioxolanes (such as 1,3-dioxolane, 1,4-dioxolane, or the like); sulfolanes, or the like.

[0070] The nonaqueous organic solvent can be used alone or in a combination of two or more.

[0071] In addition, when the carbonate-based solvent is used, a cyclic carbonate and a chain carbonate can be mixed and used. The cyclic carbonate and the chain carbonate can be mixed in a volume ratio of about 1:1 to about 1:9.

[0072] Lithium salts dissolved in non-aqueous organic solvents supply lithium ions in the battery, ensure the basic operation of rechargeable lithium batteries, and improve the transport of lithium ions between the positive and negative electrodes. Examples of lithium salts include 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 from 1 to 20), lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluoro(oxalato)borate (LiDFOB), lithium difluorobis(oxalato)phosphate (LiDFBOP), and lithium bis(oxalato)borate (LiBOB).

[0073] Rechargeable lithium battery

[0074] Rechargeable lithium batteries can be classified into cylindrical, prismatic, pouch, or coin-type batteries, etc. according to their shape. Figures 2 to 5 To illustrate a rechargeable lithium battery according to embodiments. Figure 2 A cylindrical battery is shown, Figure 3 A prismatic battery is shown, and Figure 4 A pouch battery is shown. With reference to Figure 5 A rechargeable lithium battery 100 can include an electrode assembly 40 (including a separator 30 between a positive electrode 10 and a negative electrode 20) and a case 50 (in which the electrode assembly 40 is accommodated). The positive electrode 10, the negative electrode 20, and the separator 30 can be impregnated with an electrolyte (not shown). As shown in Figures 2 to 5 A rechargeable lithium battery 100 can include a sealing member 60 that seals the case 50. In Figure 2 A rechargeable lithium battery 100 can include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. As shown in Figure 3 A rechargeable lithium battery 100 can include electrode tabs 70 (which can be, for example, a positive electrode tab 71 and a negative electrode tab 72) that function as an electrical path for guiding the electric current generated in the electrode assembly 40 to the outside of the battery. Figure 4 Figure 5 As non-limiting examples, rechargeable lithium batteries according to embodiments can be used in automobiles, mobile phones, and / or various types of electronic devices.

[0075] As non-limiting examples, rechargeable lithium batteries according to embodiments can be used in automobiles, mobile phones, and / or various types of electronic devices.

[0076] Figures 6 to 9 ​FIG. 1 is a schematic view of a rechargeable lithium battery according to an embodiment of the present disclosure. FIG. 2 is a schematic view of a rechargeable lithium battery according to another embodiment of the present disclosure. Figure 6 and Figure 7 As discussed above, the positive electrode active material layer AML1 (see FIG. 1) can include first particles PTC1, second particles PTC2, third particles PTC3, a conductive material CDM, and a binder BND. The plurality of first particles PTC1, the plurality of second particles PTC2, and the plurality of third particles PTC3 can constitute a first active material according to an embodiment of the present disclosure. Figure 1 ) can include first particles PTC1, second particles PTC2, third particles PTC3, a conductive material CDM, and a binder BND. The plurality of first particles PTC1, the plurality of second particles PTC2, and the plurality of third particles PTC3 can constitute a first active material according to an embodiment of the present disclosure.

[0077] Referring to Figure 8 and Figure 9 , the positive electrode active material layer AML1 can further include fourth particles PTC4. The plurality of first particles PTC1, the plurality of second particles PTC2, the plurality of third particles PTC3, and the plurality of fourth particles PTC4 can constitute a second active material according to some embodiments of the present disclosure.

[0078] The first active material (PTC1, PTC2, and PTC3) 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. Each of the amount of the binder BND and the conductive material CDM can be about 0.5 wt% to about 5 wt% with respect to 100 wt% of the positive electrode active material layer AML1.

[0079] If the positive electrode active material layer AML1 further includes the fourth particles PTC4, the second active material (PTC1, PTC2, PTC3, and PTC4) can be about 90 wt% to about 99 wt% with respect to 100 wt% of the positive electrode active material layer AML1. Each of the content of the binder BND and the conductive material CDM 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, the second particles PTC2, the third particles PTC3, the fourth particles PTC4, and the conductive material CDM to each other. The binder BND can include at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an oxirane-containing polymer, 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 the present disclosure is not limited to these examples.

[0081] The conductive material CDM can be used to improve the 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 without limitation. For example, the conductive material CDM 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 containing copper, nickel, aluminum, silver, etc., and having a form of a metal powder or a metal fiber; conductive polymers such as polyphenylene derivatives; or a mixture thereof.

[0082] Hereinafter, each of the first, second, third, and fourth particles PTC1, PTC2, PTC3, and PTC4 will be explained in more detail.

[0083] First particle

[0084] The first particle PTC1 can include a lithium compound represented by Chemical Formula 1 having an olivine structure:

[0085] Chemical Formula 1

[0086] Li a1 Mn x1 Fe y1 A z1 PO 4-c1

[0087] In Chemical Formula 1, 0.8 < a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0.15 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.05, 0 ≤ c1 ≤ 0.05, and x1 + y1 + z1 = 1. A can be a dopant doped in the first particle, and A can be at least one of Al, Ti, V, and Mg.

[0088] The dopant can have an effect of controlling the uniform growth of the first primary particle of the first particle PTC1, thereby improving the charging and discharging efficiency, low-temperature properties, and life characteristics of the rechargeable lithium battery including the first particle.

[0089] The first particle PTC1 is advantageous in that it has high economic feasibility, excellent structural stability, and high energy density. Since iron is the main component, the first particle PTC1 is relatively inexpensive, and since the first particle PTC1 is structurally stable, a chemical change is relatively small even when the particle is subjected to repeated charging and discharging.

[0090] The first particle PTC1 can be a lithium iron phosphate-based (hereinafter, LFP) positive electrode active material having an olivine crystal structure in which iron is partially substituted with manganese. Since the first particle PTC1 includes manganese, a higher average voltage and a higher energy density can be achieved compared to LFP.

[0091] In an embodiment, each of the first PTC particles 1 may include a coating on its surface. The coating may cover the entire surface of the first PTC particles 1 or may cover a portion of the surface of the first PTC particles 1. For example, the coating may include a carbon element and / or a carbon-containing compound. Due to the coating, the first PTC particles 1 may have improved structural stability and electrical conductivity.

[0092] The coating may further include a metal-containing compound comprising at least one of an aluminum compound, a titanium compound, a magnesium compound, and a vanadium compound. The metal-containing compound (such as an aluminum compound, a titanium compound, a magnesium compound, and a vanadium compound) may be, for example, a metal oxide, a metal hydroxide, a metal carbonate, a synthetic compound thereof, or a mixture thereof. The metal-containing compound may further include other metal or non-metal elements. For example, the metal-containing compound may further include lithium.

[0093] The first particle PTC1 may further include carbon derived from the coating layer. The amount of carbon (ie, carbon element) in the first particle PTC1 may be about 0.5 wt % to about 5 wt %, about 0.5 wt % to about 3 wt %, or about 0.5 wt % to about 2 wt %.

[0094] The first particles PTC1 may have a single particle form and / or a secondary particle form. For example, the first particles PTC1 may exist only in a single particle form, only in a secondary particle form, or in a form of a mixture of a single particle and secondary particles. Figure 6 The first particle PTC1 in the form of a single particle will be explained and reference will be made to Figure 7 The first particle PTC1 in the form of a secondary particle is explained.

[0095] In the embodiment, reference Figure 6 , the first particle PTC1 may have a single particle form. In the description, a single particle may refer to a single particle without a grain boundary inside. A single particle has a phase of one morphology and may refer to a single particle, a monolithic structure, a monolithic structure, or a non-aggregated particle (wherein the particle exists as an independent phase that is not aggregated). For example, a single particle may be a single crystal. Otherwise, a single particle may be a particle containing several crystals. A single particle may be in a single, separate form.

[0096] If the first particles PTC1 are single particles, each of the first particles PTC1 may include at least one first primary particle. In an embodiment, the first particles PTC1 may have a spherical or ellipsoidal shape in which the first primary particles are attached. In another embodiment, although the first primary particles are attached, the first particles PTC1 may not have a spherical shape but may have a random shape.

[0097] If the first particles PTC1 are single particles, the first particles PTC1 can be provided in various sizes. For example, the average diameter of the first particles PTC1 can be about 0.5 μm to about 2.5 μm or about 1 μm. The minimum particle diameter of the first particles PTC1 (e.g., the particle diameter of the smaller first particles PTC1, i.e., "first primary particles" as used herein refer to single particle first particles PTC1 whose size corresponds to the minimum particle diameter), i.e., the size of the first primary particles can be about 100 nm to about 500 nm or about 100 nm to about 200 nm. In embodiments, the average diameter can be measured by a particle size analyzer. The average diameter (D 50 ) can mean the diameter of the particles whose cumulative volume is about 50% by volume in the particle size distribution.

[0098] In embodiments, the diameter (i.e., size) of the first primary particles can mean the diameter measured by randomly selecting about 30 first primary particles in an electron microscope image of the first particles PTC1.

[0099] If the first particles PTC1 are single particles, the porosity of the first particles PTC1 can be less than about 20%. The porosity (n) can be defined as the pore volume (V p ) divided by the total volume of the particles (V t ), or The span value of the first particles PTC1 analyzed by the particle size analyzer can be in the range of about 0.3 to about 0.75. The span value is represented by (D 90 -D 10 ) / D 50 . 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.

[0100] Referring again to Figure 7 , in other embodiments, the first particles PTC1 can have a secondary particle form. The secondary particles can have a polycrystalline form, and be in a form in which two or more first primary particles are aggregated. In other words, one first particle PTC1 can include a plurality of first primary particles aggregated with each other. The first particles PTC1 can have a spherical or ellipsoidal shape.

[0101] In an embodiment, if the first particulate PTC1 is in a secondary particulate form, the first particulate PTC1 can further include a grain boundary coating on a surface of each first primary particle. The grain boundary coating can be present in the first particulate PTC1. The grain boundary coating can be formed along an interface between the first primary particles inside the first particulate PTC1. In other words, the grain boundary coating can refer to a layer formed of a material coated on a grain boundary in the first particulate 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 of an aluminum-containing compound, a titanium-containing compound, a magnesium-containing compound, and a vanadium-containing compound.

[0102] If the first particulate PTC1 is a secondary particulate, the inside of the above-described first particulate PTC1 can mean the entire inside of the first particulate PTC1 except for the surface of the first particulate PTC1. For example, the inside of the first particulate PTC1 can mean the entire inside from a depth of about 10 nm from the surface of the first particulate PTC1, or a region from a depth of about 10 nm to a depth of about 2 μm.

[0103] When the first particulate PTC1 is a secondary particulate and the first particulate PTC1 further includes the grain boundary coating, the structural stability can be enhanced, and a uniform coating layer can be formed on the surface of the first particulate PTC1. In addition, the electrical conductivity of the first particulate PTC1 can be further improved.

[0104] When the first particulate PTC1 is a secondary particulate, the first particulate PTC1 can further include carbon originating from the coating and / or the grain boundary coating. The amount of carbon in the first particulate 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%. If the first particulate PTC1 is a secondary particulate, the amount of carbon can be greater than in a case where the first particulate PTC1 is a single particulate.

[0105] If the first particulate PTC1 is a secondary particulate, the average diameter of the first particulate 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 diameter of the first particulate PTC1 can be about 5 μm. As discussed above, the average diameter can be measured using a particle size analyzer. The average diameter (D 50 ) can mean the diameter of a particle at which the cumulative volume is about 50 vol% in a particle size distribution.

[0106] If the first particle PTC1 is a secondary particle, the average diameter of the first primary particle can be less than about 200 nm. For example, the average diameter of the first primary particle can be about 10 nm to about 200 nm, about 20 nm to about 200 nm, about 50 nm to about 200 nm, about 100 nm to about 200 nm, or about 50 nm to about 150 nm. In an embodiment, the average diameter of the first primary particle can mean a diameter measured by randomly selecting about 30 primary particles in an electron microscope image of the positive electrode active material. The size of the first primary particle can be uniform.

[0107] If the first particle PTC1 has a secondary particle form, the diameter of the first primary particle can be smaller than in the case where the first particle PTC1 is a single particle. For example, in the case where the first particle PTC1 has a secondary particle form, the diameter of the first primary particle can be about 50 nm smaller than the diameter of the first primary particle in the case where the first particle PTC1 has a single crystal form.

[0108] If the first particle PTC1 is a secondary particle, the average particle diameter of the first particle PTC1 and the average diameter of the first primary particle satisfy the above ranges, and if the size (diameter) of the first primary particle is uniform, the charge and discharge capacity of the rechargeable lithium battery including the particle and the capacity at a low temperature can be improved.

[0109] If the first particle PTC1 is a secondary particle, the porosity of the first particle PTC1 can be about 20% to about 40%. The span value of the first particle PTC1 analyzed by a particle size analyzer can be about 0.3 to about 0.75.

[0110] If the first particle PTC1 is a secondary particle, the positive electrode active material layer AML1 (see Figure 1 ) can be smoothly adhered to the positive electrode current collector COL1 by a relatively small amount of the binder BND. For example, the amount of the binder BND can be about 0.5 wt% to about 3 wt% based on about 100 wt% of the positive electrode active material layer AML1. These amounts of the binder are possible because the interaction between the first particle PTC1 and the positive electrode current collector COL1 increases and because the average diameter of the first particle PTC1 is large. If the amount of the binder BND included in the positive electrode active material layer AML1 is reduced, the amount of the positive electrode active material can be correspondingly increased, thereby improving the capacity and the energy density of the battery. In addition, by reducing the amount of the binder that increases the resistance, the electrical conductivity of the positive electrode can be improved.

[0111] Second particle

[0112] The second particle PTC2 can include a lithium compound having a spinel structure, represented by Chemical Formula 2:

[0113] Chemical Formula 2

[0114] Li a2 Mn x2 B y2 O 4-c2

[0115] In Chemical Formula 2, 0.8 < a2≤ 1.2, 1.9 ≤ x2≤ 2.05, 0 ≤ y2≤ 0.05, 0 ≤ c2≤ 0.05, and B can be a dopant, which is at least one of Al and Mg. The dopant can have an effect of uniformly growing the second primary particles of the second particles PTC2, thereby improving the charge and discharge efficiency, low-temperature properties, and life characteristics of the rechargeable lithium battery.

[0116] In one or more embodiments, in Chemical Formula 2, 0.8 < a2≤ 1.2, 1.95 ≤ x2≤ 2.05, 0 ≤ y2≤ 0.05, 0 ≤ c2≤ 0.05, and 2 ≤ x2+y2≤ 2.1 can be satisfied.

[0117] In one or more embodiments, in Chemical Formula 2, 0.8 < a2≤ 1.2, 1.95 ≤ x2≤ 2, 0 ≤ y2≤ 0.05, 0 ≤ c2≤ 0.05, and x2+y2= 2 can be satisfied.

[0118] The second particles PTC2 have the advantages of high output properties, high structural stability, high average voltage, and excellent life characteristics. The second particles PTC2 can have a spinel structure composed of a lattice structure of tetrahedrons and octahedrons. Because the lattice structure has various channels, lithium ions can be smoothly intercalated / deintercalated, thereby producing excellent output properties. The second particles PTC2 include manganese, and thus can be structurally stable. Due to the structural stability, the electrochemical properties of the particles can be maintained even at high voltage, thereby allowing a battery including the particles to operate at high voltage and providing excellent life characteristics to the battery.

[0119] The second particles PTC2 are lithium manganese oxides, and can be positive electrode active materials in which cobalt in lithium cobalt oxide is replaced with manganese. In embodiments of the present disclosure, the amount of cobalt in the second particles PTC2 can be so small that it is effectively omitted. For example, the amount of cobalt in the second particles PTC2 can be about 100 ppm or less. The amount of cobalt means the amount of cobalt in the second particles PTC2 with respect to the amount of transition metals other than lithium. Because cobalt is substantially omitted from the positive electrode active material according to the present disclosure, an economical rechargeable lithium battery having high capacity and operating voltage can be provided.

[0120] Referring again to Figure 6 and Figure 7The second particles PTC2 can have a polycrystalline form, and can each include a secondary particle in which two or more second primary particles are aggregated. In other words, one second particle PTC2 can include a plurality of second primary particles aggregated with each other. The second particle PTC2 can have a spherical shape of aggregation of the second primary particles. But the aggregated second primary particles are aggregated, the second particle PTC2 can also have a random shape.

[0121] The average diameter of the second particle PTC2 can be about 3 μm to about 20 μm, about 3 μm to about 10 μm, about 4 μm to about 15 μm, or about 5 μm to about 10 μm. For example, the average diameter of the second particle PTC2 can be about 6 μm. As discussed above, the average diameter can be measured by a particle size analyzer. The average diameter (D 50 ) can mean the diameter of the particles of which the cumulative volume is about 50% by volume in the particle size distribution.

[0122] The average diameter of the second primary particles constituting the second particle PTC2 can be about 3 μm or less. For example, the diameter of the second primary particles can be about 300 nm to about 3 μm, about 0.5 μm to about 3 μm, about 1 μm to about 3 μm, or about 2 μm to about 3 μm. In an embodiment, the average diameter of the second primary particles can mean the diameter measured by randomly selecting about 30 second primary particles in an electron microscope image of the positive electrode active material. The size of the second primary particles can be uniform. The average diameter of the second primary particles can be greater than the average diameter of the first primary particles. The difference between the average diameter of the second primary particles and the average diameter of the first primary particles can be about 300 nm or more.

[0123] In an embodiment, the second particle PTC2 can include a second coating layer on the surface thereof. By including the second coating layer, the structural collapse of the second particle PTC2 due to repeated charging and discharging can be effectively suppressed.

[0124] The second coating layer can include a metal-containing compound including an aluminum-containing compound, a magnesium-containing compound, or a combination thereof. The metal-containing compound in the second coating layer can be, for example, a metal oxide, a metal hydroxide, a metal carbonate, a synthetic compound thereof, or a mixture thereof. The metal-containing compound can further include other metal or non-metal elements. For example, the second coating layer can further include lithium, manganese, and / or nickel.

[0125] The method for measuring the metal content in the second coating of the second particles PTC2 can include performing a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) analysis on the second particles PTC2. Through the analysis, the aluminum and / or magnesium content in the second coating can be confirmed. As a method for measuring the metal content in the second coating, in addition to SEM-EDS, inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), etc. can be used.

[0126] Third particle

[0127] The third particles PTC3 can include a lithium compound represented by Chemical Formula 3:

[0128] Chemical Formula 3

[0129] Li a3 Ni x3 Co y3 Mn z3 E w1 O 2-c3

[0130] In Chemical Formula 3, 0.8 < a3 ≤ 1.2, 0.5 ≤ x3 ≤ 0.8, 0 ≤ y3 ≤ 0.10, 0.1 ≤ z3 ≤ 0.35, 0 ≤ w1 ≤ 0.1, 0 ≤ c3 ≤ 0.05, and E can be a dopant selected from Al, Ti, Mg, Zr, Mo, and Nb. The dopant can improve the surface stability and structural stability of the third particles PTC3.

[0131] In one or more embodiments, in Chemical Formula 3, 0.8 < a3 ≤ 1.2, 0.5 ≤ x3 ≤ 0.8, 0.05 ≤ y3 ≤ 0.10, 0.1 ≤ z3 ≤ 0.35, 0 ≤ w1 ≤ 0.1, 0 ≤ c3 ≤ 0.05, and x3 + y3 + z3 + w1 = 1 can be satisfied.

[0132] The amount of cobalt in the third particles PTC3 can be about 10 mol% or less. The amount of cobalt means the amount of cobalt in the third particles PTC3 with respect to the amount of transition metals other than lithium.

[0133] The third particles PTC3 provide the advantages of excellent lifespan characteristics and high energy density.

[0134] In embodiments, referring to Figure 6 The third particles PTC3 can have a single particle form. The third particles PTC3 can include at least one third primary particle. In embodiments, the third particles PTC3 can have a spherical or ellipsoidal shape in which the third primary particles are attached. In another embodiment, although the third primary particles are attached, the third particles PTC3 can not have a spherical shape, but can have a random shape. Referring toFigure 10B 、 Figure 11 and Figure 12 If the third particles PTC3 in the form of single particles have the attached form of third primary particles, the third particles PTC3 in the form of single particles may be less structured than the first particles PTC1 in the form of secondary particles and the second particles PTC2 in the form of secondary particles described above. That is, the third particles PTC3 may have a more random form.

[0135] In embodiments, each of the third PTC particles 3 may include a third coating layer on its surface. By including the third coating layer, structural collapse of the third PTC particles 3 due to repeated charging and discharging can be effectively suppressed. Accordingly, the lifespan characteristics of a rechargeable lithium battery including the third particles can be improved.

[0136] The third coating layer may include an aluminum-containing compound, a titanium-containing compound, a magnesium-containing compound, a zirconium-containing compound, a molybdenum-containing compound, a niobium-containing compound, or a combination thereof. The metal-containing compound in the third coating layer may be a metal oxide, a metal hydroxide, a metal carbonate, a compound thereof, or a mixture thereof. The metal-containing compound may further include other metal or non-metal elements. For example, the third coating layer may further include lithium, manganese, and / or nickel.

[0137] The average diameter of the third particles PTC3 may be about 2 μm to about 15 μm, about 2 μm to about 10 μm, or about 2 μm to about 5 μm. For example, the average diameter of the third particles PTC3 may be about 6 μm. The average diameter of the third particles PTC3 may be greater than the average diameter of the first particles PTC1. As discussed above, the average diameter can be measured by a particle size analyzer. Average diameter (D 50 ) may refer to the diameter of particles accounting for approximately 50% by volume of the cumulative volume in a particle size distribution. The average diameter of the third particles PTC3 may be measured by a particle size analyzer, and the average diameter of the third primary particles may be measured by randomly selecting approximately 30 primary particles in an electron microscope image of the positive electrode active material.

[0138] If the third particles PTC3 have a form in which a plurality of third primary particles are attached to each other, an average diameter of the third primary particles may be greater than an average diameter of the first particles PTC1.

[0139] The method for measuring the content of the metal elements in the third coating of the third particles PTC3 can include performing a scanning electron microscope-energy dispersive X-ray spectroscopy (SEM-EDS) analysis on the third particles PTC3. Through the analysis, the content of aluminum, titanium, magnesium, zirconium, molybdenum, and / or niobium in the third coating can be confirmed. As the method for measuring the content of the metal elements in the third coating, in addition to SEM-EDS, inductively coupled plasma-mass spectrometry (ICP-MS), inductively coupled plasma optical emission spectroscopy (ICP-OES), etc. can be used.

[0140] The third particles PTC3 can include a lithium nickel-based complex oxide as a nickel-based active material. In an embodiment, the third particles PTC3 can include a high nickel-based positive electrode active material including a high content of nickel. The high nickel-based positive electrode active material can provide a high capacity and a high performance.

[0141] Fourth particle

[0142] The fourth particles can include a lithium compound represented by Chemical Formula 4:

[0143] Chemical Formula 4

[0144] Li a4 Ni x4 Mn y4 D z4 O c4

[0145] In Chemical Formula 4, 1.1 < a4 ≤ 1.6, 0.2 ≤ x4 ≤ 0.5, 0.5 ≤ y4 ≤ 0.8, 0 ≤ z4 ≤ 0.05, 2 ≤ c4 ≤ 2.3, and D can be a dopant that is at least one transition metal having an oxidation number of 4. For example, D can be vanadium (V), chromium (Cr), tungsten (W), zirconium (Zr), and hafnium (Hf). The dopant can improve the surface stability and the structural stability of the fourth particles PTC4.

[0146] In one or more embodiments, in Chemical Formula 4, 1.1 < a4 ≤ 1.6, 0.2 ≤ x4 ≤ 0.5, 0.5 ≤ y4 ≤ 0.8, 0 ≤ z4 ≤ 0.05, 2 ≤ c4 ≤ 2.3, and x4 + y4 + z4 = 1 can be satisfied.

[0147] The fourth particles PTC4 have the advantage of a high capacity and an energy density.

[0148] The fourth particles PTC4 can have a single particle form and / or a secondary particle form. Hereinafter, the fourth particles PTC4 having the single particle form will be explained with reference to FIG. 6, and the fourth particles PTC4 having the secondary particle form will be explained with reference to FIG. 7. Figure 8 The fourth particles PTC4 having the single particle form will be explained with reference to FIG. 6, and the fourth particles PTC4 having the secondary particle form will be explained with reference to FIG. 7. Figure 13 The fourth particles PTC4 having the secondary particle form will be explained with reference to FIG. 7.

[0149] If the fourth particle PTC4 is a single particle, the fourth particle PTC4 can include a fourth primary particle. In embodiments, the fourth particle PTC4 can have a spherical or ellipsoidal shape in which the fourth primary particle is attached. In other embodiments, the fourth particle PTC4 can not have a spherical shape, but can have a random shape, although the fourth primary particle is attached.

[0150] In Figure 8 and Figure 9 , the fourth particle PTC4 is shown to have a form including only one particle. But the fourth particle PTC4 can have a spherical or ellipsoidal shape in which two or more fourth primary particles are attached, or a random shape. For example, the fourth particle PTC4 can have a random form in which fourth primary particles are aggregated, as shown in Figure 13 In Figure 10B and Figure 13 , the aggregated shape of the fourth primary particles can be relatively more irregular than the aggregated shape of the first primary particles described above.

[0151] If the fourth particle PTC4 is a single particle, the fourth particle PTC4 can be provided in various sizes. For example, the average diameter of the fourth particle PTC4 can be about 3 μm to about 7 μm. The minimum diameter of the fourth particle PTC4 (i.e., the size of the fourth primary particle) can be about 100 nm to about 300 nm. The average diameter of the fourth particle PTC4 can be greater than the average diameter of the first particle PTC1. If the fourth particle PTC4 includes a plurality of single particles, the average diameter of the fourth primary particles of the fourth particle PTC4 can be greater than the average diameter of the first primary particles.

[0152] In embodiments, each of the fourth particles PTC4 can include a fourth coating layer on the surface thereof. The coating layer can inhibit structural collapse of the fourth particle PTC4 due to repeated charging and discharging. Accordingly, the coating layer can improve the life characteristics of the rechargeable lithium battery including the fourth particle.

[0153] The fourth coating layer can include a metal-containing compound including a boron-containing compound, an aluminum-containing compound, or a combination thereof. For example, the metal-containing compound in the fourth coating layer can be a metal oxide, a metal hydroxide, a metal carbonate, a synthetic compound thereof, or a mixture thereof. The metal-containing compound can further include other metal or non-metal elements. For example, the fourth coating layer can further include lithium, manganese, and / or nickel.

[0154] Referring to Figure 13In another embodiment, the fourth particles PTC4 can have a secondary particle form. The secondary particles can have a polycrystalline form in which two or more fourth primary particles are aggregated. In other words, the fourth particles PTC4 can include a plurality of fourth primary particles aggregated with each other. More specifically, the fourth particles PTC4 having a secondary particle form can have an aggregated form that can be divided into a group of unit structures. The aggregated form that can be divided into a group of unit structures can have a smaller sphericity than the first particles PTC1 in the secondary particle form. In the aggregated form that can be divided into a group of unit structures, the boundary of the aggregate can not be clear compared to the first particles PTC1 in the secondary particle form.

[0155] If the fourth particles PTC4 are secondary particles, the average diameter of the fourth particles PTC4 can be about 5 μm to about 10 μm. For example, the average diameter of the fourth particles PTC4 can be about 7 μm. The average diameter of the fourth particles PTC4 can be greater than the average diameter of the first particles PTC1. As discussed above, the average particle diameter can be measured by a particle size analyzer. The average diameter (D50) means the diameter of the particles at which the cumulative volume is about 50% by volume in the particle size distribution. 50 ) means the diameter of the particles at which the cumulative volume is about 50% by volume in the particle size distribution.

[0156] If the fourth particles PTC4 are secondary particles, the average diameter of the fourth primary particles can be about 500 nm or less. For example, the average diameter of the fourth primary particles can be about 100 nm to about 500 nm. In an embodiment, the average diameter of the fourth primary particles can mean the diameter measured by optionally selecting about 30 primary particles in an electron microscope image of the positive electrode active material. The size of the fourth primary particles can be uniform.

[0157] In an embodiment, if the fourth particles PTC4 have a secondary particle form, a grain boundary coating layer can be formed on the surface of each of the fourth primary particles. The grain boundary coating layer can be present in the fourth particles PTC4. For example, the grain boundary coating layer can be formed along the interface between the fourth primary particles inside each of the fourth particles PTC4. In other words, the grain boundary coating layer can mean a layer formed of a material coated on the grain boundaries in the fourth particles PTC4. The grain boundary coating layer can include at least one transition metal having an oxidation number of 4. For example, the grain boundary coating layer can include a boron-containing compound, an aluminum-containing compound, or a combination thereof.

[0158] If the fourth particles PTC4 are secondary particles, the inside of the fourth particles PTC4 can mean the entire inside of the fourth particles PTC4 except the surface of the fourth particles PTC4. For example, the inside of the fourth particles PTC4 can mean the entire inside from a depth of about 10 nm from the surface of the fourth particles PTC4, or a region from a depth of about 10 nm to a depth of about 2 μm.

[0159] If the fourth particle PTC4 is a secondary particle including a grain boundary coating, the structural stability can be enhanced, and a uniform coating can be formed on the surface of the fourth particle PTC4. In addition, since the fourth particle PTC4 further includes a grain boundary coating, the life characteristics of the rechargeable lithium battery can be further improved.

[0160] In embodiments of the present disclosure, cobalt can be substantially omitted from the fourth particle PTC4. For example, the amount of cobalt from the fourth particle PTC4 can be about 100 ppm or less. The amount of cobalt means the amount of cobalt in the fourth particle PTC4 with respect to the amount of transition metals other than lithium. In addition, cobalt can also be substantially omitted from the second particle PTC2. Since cobalt can be substantially omitted from the positive electrode active material according to the present disclosure, an economical rechargeable lithium battery having a high capacity and an operating voltage can be provided.

[0161] Also, the fourth particle PTC4 according to embodiments of the present disclosure can include Li 1.5 Ni 0.25 Mn 0.75 O2. However, this is merely an illustration, and the present disclosure is not limited thereto. Further, the fourth particle PTC4 can be a lithium manganese-based oxide (LMR) containing excess lithium and have a mixed structure of a layered phase (LiMnO2) and a rock salt phase (Li2MnO3). During a charging and discharging process, the rock salt phase is activated, and a high capacity can be achieved from a capacity additionally generated by an oxidation-reduction reaction.

[0162] First active material

[0163] Referring to Figure 6 and Figure 7 The first active material according to some embodiments of the present disclosure will be explained in more detail. The first active material of the present disclosure can include the first particle PTC1, the second particle PTC2, and the third particle PTC3.

[0164] In the first active material, the first particle PTC1 and the second particle PTC2 can constitute a main active material. The amount of the main active material can be about 50 parts by weight to about 85 parts by weight, based on about 100 parts by weight of the first active material.

[0165] In the main active material, the mixing ratio of the first particle PTC1 and the second particle PTC2 can be about 40:60 to about 70:40 or about 40:60 to about 65:35, based on weight.

[0166] The amount of manganese (i.e., the manganese element) in the main active material can be about 50 mol% to about 90 mol% or about 60 mol% to about 80 mol%. The amount of manganese means the amount of Mn with respect to the metal elements other than lithium in the main active material.

[0167] If the main active material satisfies the mixing ratio range and the manganese content range, the low life characteristics and the difficult-to-process property of the first particles PTC1 can be improved, while minimizing the reduction in the energy density of the main active material. That is, within the mixing ratio range and the manganese content range, the main active material can maintain the economic feasibility and the structural stability, which are advantages of the first particles PTC1, while improving the life characteristics and ensuring easy processing. More specifically, by mixing the first particles PTC1 and the second particles PTC2 to form the main active material, the low life characteristics and the difficult-to-process property of the first particles PTC1 can be improved. Although this process can result in some undesirable reduction in the energy density of the main active material, the reduction in the energy density can be minimized if the main active material satisfies the mixing ratio range and the manganese content range. Further, the reduction in the energy density can be compensated for by adding the third particles PTC3, which will be explained below.

[0168] The first active material can include the first particles PTC1, the second particles PTC2, and the third particles PTC3. In the first active material, the mixing ratio of the first particles PTC1 and the second particles PTC2 to the third particles PTC3 can be about 50:50 to about 85:15 based on weight. In the first active material, the manganese content of the first active material can be about 50 mol% to about 80 mol% or about 50 mol% to about 70 mol%. The amount of manganese means the amount of Mn with respect to the amount of metal elements other than lithium in the first active material. The amount of the third particles PTC3 can be about 10 parts by weight to about 50 parts by weight or about 15 parts by weight to about 50 parts by weight based on 100 parts by weight of the first active material. Otherwise, the amount of the third particles PTC3 can be about 30 parts by weight to about 50 parts by weight.

[0169] When the first active material includes the first particles PTC1, the second particles PTC2, and the third particles PTC3 to satisfy the mixing ratio range and the manganese content, the material can have all the advantages of the first particles PTC1, the second particles PTC2, and the third particles PTC3. More specifically, the first active material can have all the advantages of the first particles PTC1 (i.e., economic feasibility, structural stability, and high energy density), the advantages of the second particles PTC2 (i.e., high average voltage and excellent life characteristics), and the advantages of the third particles PTC3 (i.e., excellent life characteristics and high energy density). That is, the energy density, the average voltage, and the life characteristics can be improved in an economically feasible manner.

[0170] A positive electrode active material according to the present disclosure can have a high powder density (PD). In embodiments, the powder density of a positive electrode active material of the present disclosure can be about 2 g / cc to about 5 g / cc, about 2.5 g / cc to about 4 g / cc, or about 2.5 g / cc to about 3.0 g / cc. This can be higher than the powder density of a common lithium iron phosphate (LFP) battery. A high powder density can help improve the life characteristics of a rechargeable lithium battery and increase the energy density of a rechargeable lithium battery. A uniform and dense distribution of active material can help sustain electrochemical reactions during charging and discharging processes, which can help improve life characteristics. More active material can be stored in a limited space, more energy per unit volume can be stored, thereby increasing energy density.

[0171] A rechargeable lithium battery including a first active material according to the present disclosure can have a high average voltage. In embodiments, the average voltage of a rechargeable lithium battery of the present disclosure can be about 3 V to about 4 V. In other embodiments, the average voltage range of the present disclosure can be about 3.6 V to about 3.8 V. Because energy density is proportional to average voltage, average voltage can help increase energy density.

[0172] A rechargeable lithium battery including a first active material according to the present disclosure can have a high energy density. In embodiments, the energy density of a rechargeable lithium battery of the present disclosure can be about 400 Wh / kg to about 600 Wh / kg, about 450 Wh / kg to about 600 Wh / kg, or about 500 Wh / kg to about 600 Wh / kg.

[0173] A rechargeable lithium battery including a first active material according to the present disclosure can have high life characteristics. In embodiments, a rechargeable lithium battery of the present disclosure can have a capacity retention rate of about 97% or more after 50 charge / discharge cycles under specific current and voltage conditions. In embodiments, if initially charged under constant current (about 0.2C) and constant voltage (about 4.25 V) conditions, then initially discharged to about 2.5 V under constant current (about 0.2C) conditions, and then charged and discharged at about 0.2C / 0.2C for 50 times, the capacity retention rate can be about 95% to about 100% or about 97% to about 99%.

[0174] Second active material

[0175] Reference will now be made in detail to some embodiments of the second active material according to the present disclosure. Figure 8 Figure 9 The second active material according to some embodiments of the present disclosure will be explained in more detail.

[0176] ​The second active material according to the present disclosure can include the first particles PTC1, the second particles PTC2, the third particles PTC3, and the fourth particles PTC4. That is, the second active material according to the present disclosure can additionally include the fourth particles PTC4 in the above-described first active material.

[0177] Since the second active material according to the present disclosure includes the fourth particles PTC4 in addition to the first particles PTC1, the second particles PTC2, and the third particles PTC3, the capacity and the energy density can be further increased.

[0178] The amount of the fourth particles PTC4 can be about 5 parts by weight to about 35 parts by weight or about 15 parts by weight to about 25 parts by weight, based on 100 parts by weight of the second active material. If the amount of the fourth particles PTC4 satisfies these ranges, the capacity and the energy density can be further increased, while the life reduction and the stability deterioration of the second active material can be minimized.

[0179] The second active material can include the first particles PTC1, the second particles PTC2, the third particles PTC3, and the fourth particles PTC4, while the first particles PTC1, the second particles PTC2, and the third particles PTC3 can constitute the first active material. In the second active material, the mixing ratio of the first active material to the fourth particles PTC4 can be about 75:25 to about 85:15, based on weight. Otherwise, the mixing ratio can be about 65:35 to about 95:5. In the second active material, the manganese content of the second active material can be about 50 mol% to about 60 mol%. The manganese content of the second active material means the amount of manganese with respect to the metal elements other than lithium in the second active material. In some cases, the manganese content of the first active material can be about 50 mol% to about 80 mol%.

[0180] If the second active material satisfies the mixing ratio range, the manganese content range of the second active material, and the manganese content range of the first active material, the energy density can be maximized. That is, within the mixing ratio range, the manganese content range of the second active material, and the manganese content range of the first active material, the second active material can improve the energy density property while maintaining the advantages of the first active material, i.e., economic efficiency, structural stability, high life characteristics, and easy processability. More specifically, the purpose of preparing the second active material by mixing the first active material and the fourth particles PTC4 can be to prepare a positive electrode active material having a higher energy density than that of the first active material. This process can cause some undesirable reduction in the average voltage and the life of the second active material. But if the second active material satisfies the mixing ratio range, the manganese content range of the second active material, and the manganese content range of the first active material, the reduction in the average voltage and the life can be minimized.

[0181] The rechargeable lithium battery including the second active material according to the present disclosure can have a high energy density. In embodiments, the energy density of the rechargeable lithium battery of the present disclosure can be about 400 Wh / kg to about 650 Wh / kg, about 500 Wh / kg to about 650 Wh / kg, or about 550 Wh / kg to about 600 Wh / kg.

[0182] The second active material according to the present disclosure can have a high powder density (PD). In embodiments, the powder density of the second active material of the present disclosure can be about 2 g / cc to about 5 g / cc, about 2.5 g / cc to about 4 g / cc, or about 2.5 g / cc to about 3.0 g / cc. This can be higher than the powder density of a common LFP battery. The high powder density can help to improve the life characteristics of the rechargeable lithium battery and increase the energy density of the rechargeable lithium battery. The uniform and dense distribution of the active material can help to sustain the electrochemical reactions during the charging and discharging processes, which can help to improve the life characteristics. Since more active material can be stored in a limited space, more energy can be stored per unit volume, thereby helping to increase the energy density.

[0183] The rechargeable lithium battery including the second active material according to the present disclosure can have a high average voltage. In embodiments, the average voltage of the rechargeable lithium battery of the present disclosure can be about 3 V to about 4 V. In other embodiments, the average voltage range of the present disclosure can be about 3.6 V to about 3.8 V. Since the energy density is proportional to the average voltage, the above high average voltage can help to increase the energy density.

[0184] The rechargeable lithium battery including the second active material according to the present disclosure can have high life characteristics. In embodiments, the rechargeable lithium battery of the present disclosure can have a capacity retention rate of about 97% or more after 50 charge / discharge cycles under specific current and voltage conditions. In embodiments, if initially charged under constant current (about 0.2C) and constant voltage (about 4.25 V) conditions, initially discharged under constant current (about 0.2C) to about 2.5 V, and then charged and discharged at about 0.2C / 0.2C for 50 times, the capacity retention rate can be about 95% to about 100% or about 97% to about 99%.

[0185] Hereinafter, embodiments and comparative examples of the present disclosure will be described. However, the embodiments are merely an illustration of the present disclosure, and the present disclosure is not limited to the embodiments.

[0186] Preparation Example 1-1: Preparation of first particle having a single particle form

[0187] Mn 0.6 Fe 0.4MnPO4manganese phosphate precursor, lithium carbonate, and titanium dioxide were mixed in a molar ratio of (Mn+Fe):Li:Ti of about 1 : 1.03:0.004. To the mixture, 10 wt% of glucose was added. The mixture was evaporated and dried by a spray drying process at a spray pressure of about 0.5 MPa at a temperature condition of about 230 °C. The dried mixture was baked at about 750 °C for about 10 hours under a nitrogen atmosphere to obtain first particles in a form of secondary particles. The average size of primary particles in the first particles was about 50 nm to about 150 nm.

[0188] Preparation Example 1-2: Preparation of first particle in a secondary particle form

[0189] MnPO4manganese phosphate precursor, lithium carbonate, and titanium dioxide were mixed in a molar ratio of (Mn+Fe):Li:Ti of about 1 : 1.03:0.004. To the mixture, 10 wt% of glucose was added. The mixture was evaporated and dried by a spray drying process at a spray pressure of about 0.5 MPa at a temperature condition of about 230 °C. The dried mixture was baked at about 750 °C for about 10 hours under a nitrogen atmosphere to obtain first particles in a form of secondary particles. The average size of primary particles in the first particles was about 50 nm to about 150 nm. 0.6 FePO4iron phosphate precursor, lithium carbonate, and titanium dioxide were mixed in a molar ratio of (Mn+Fe):Li:Ti of about 1 : 1.03:0.004. To the mixture, 10 wt% of glucose was added. The mixture was evaporated and dried by a spray drying process at a spray pressure of about 0.5 MPa at a temperature condition of about 230 °C. The dried mixture was baked at about 750 °C for about 10 hours under a nitrogen atmosphere to obtain first particles in a form of secondary particles. The average size of primary particles in the first particles was about 50 nm to about 150 nm. 0.4

[0190] Preparation Example 1-3: Preparation of second particle

[0191] In 100 ml of distilled water, 0.170 g of MnSO4-H2O and 0.228 g of (NH4)2S2O8 were dissolved, and to this, sulfuric acid was added to adjust the pH to 1, followed by a reaction at about 130 °C for about 10 hours to obtain a solid precipitate. The precipitate thus obtained was washed several times with distilled water, and dried at about 300 °C for about 3 hours to obtain MnO2 in a solid form having an average diameter of about 5 μm.

[0192] Li2CO3and the MnO2thus synthesized were mixed so that the molar ratio of lithium and manganese became about 1 : 2, and then the mixture was heated at about 600 °C for about 10 hours to synthesize LiMn2O4particles having an average diameter of about 7 μm.

[0193] Preparation Example 1-4: Preparation of third particle

[0194] ​A nickel-based precursor was prepared using a co-precipitation method. In particular, nickel sulfate (NiS04-6H20), cobalt sulfate (CoS04-7H20), and manganese sulfate (MnS04-H20) as raw materials of a nickel-based metal hydroxide in a molar ratio of about 6:1:3 were dissolved in distilled water as a solvent to prepare a metal raw material mixture. The metal raw material mixture, ammonia water, and sodium hydroxide were put into a reactor and reacted. The slurry solution in the reactor was filtered and rinsed with high-purity distilled water. The rinsed material was dried in a hot air oven at about 210°C for about 24 hours to obtain a precursor (Ni 0.6 Co 0.1 Mn 0.3 (OH)2) powder.

[0195] The nickel-based precursor and anhydrous lithium hydroxide (Li2C03) were dry-mixed using a Henschel mixer. The mixing was performed so that the molar ratio of lithium and transition metals was about 1:1. The transition metal means the sum of transition metals (Ni+Co+Mn) contained in the nickel-based precursor. Flux was additionally added to the mixture, and heat treatment (i.e., a baking process) was performed at about 850°C for about 15 hours under an oxygen atmosphere to synthesize third particles of a nickel-based positive electrode active material. The third particles were milled using a jet mill at a pressure of about 3 bar.

[0196] The third particles were added to distilled water and rinsed. Boron oxide and aluminum oxide corresponding to about 3 mol% based on the sum of transition metals of the third particles were added to perform boron and aluminum coating. The third particles were dried at about 150°C for about 12 hours, and heated (i.e., surface treatment) at about 700°C for about 15 hours under an oxygen atmosphere. The chemical formula of the third particles thus prepared was LiNi 0.6 Co 0.1 Mn 0.3 O2.

[0197] Preparation Example 1-5: Preparation of fourth particle

[0198] The transition metal precursor (Ni 0.35 Mn 0.65 )(OH)2and a lithium source Li2C03were mixed in a weight ratio of (Ni+Mn):Li of about 1:1.3. Baking was performed at about 600°C for about 10 hours under an oxygen atmosphere to obtain fourth particles in the form of secondary particles. The average diameter of the fourth particles was about 5 μm ~ 10 μm, and the average diameter of the fourth primary particles was about 100 nm ~ about 500 nm.

[0199] Preparation Example 2-1: Preparation of primary active material

[0200] The first particles of Preparation Example 1-1 and the second particles of Preparation Example 1-3 were mixed in a weight ratio of about 65:35 to prepare a main active material. In this case, the amount of manganese with respect to the metal elements other than lithium in the main active material was about 60 mol%.

[0201] Preparation Example 2-2

[0202] The first particles of Preparation Example 1-1 and the second particles of Preparation Example 1-3 were mixed in a weight ratio of about 50:50 to prepare a main active material. In this case, the amount of manganese with respect to the metal elements other than lithium in the main active material was about 70 mol%.

[0203] Preparation Example 2-3

[0204] The first particles of Preparation Example 1-1 and the second particles of Preparation Example 1-3 were mixed in a weight ratio of about 40:60 to prepare a main active material. In this case, the amount of manganese with respect to the metal elements other than lithium in the main active material was about 80 mol%.

[0205] Example 1-1: Preparation of first active material

[0206] The main active material of Preparation Example 2-1 and the third particles of Preparation Example 1-4 were mixed in a weight ratio of about 70:30 to prepare a first active material. The amount of manganese of the first active material was about 50 mol%.

[0207] Example 1-2

[0208] The main active material of Preparation Example 2-2 and the third particles of Preparation Example 1-4 were mixed in a weight ratio of about 85:15 to prepare a first active material. The amount of manganese of the first active material was about 65 mol%.

[0209] Example 1-3

[0210] The main active material of Preparation Example 2-2 and the third particles of Preparation Example 1-4 were mixed in a weight ratio of about 70:30 to prepare a first active material. The amount of manganese of the first active material was about 60 mol%.

[0211] Example 1-4

[0212] The main active material of Preparation Example 2-2 and the third particles of Preparation Example 1-4 were mixed in a weight ratio of about 60:40 to prepare a first active material. The amount of manganese of the first active material was about 55 mol%.

[0213] Example 1-5

[0214] The first active material was prepared by mixing the primary active material of Preparation 2-3 and the third particles of Preparation 1-4 in a weight ratio of about 80:20. The amount of manganese in the first active material was about 70 mol%.

[0215] Example 1-6

[0216] The first active material was prepared by mixing the primary active material of Preparation 2-3 and the third particles of Preparation 1-4 in a weight ratio of about 70:30. The amount of manganese in the first active material was about 65 mol%.

[0217] Example 1-7

[0218] The first active material was prepared by mixing the primary active material of Preparation 2-3 and the third particles of Preparation 1-4 in a weight ratio of about 60:40. The amount of manganese in the first active material was about 60 mol%.

[0219] Example 1-8

[0220] The first active material was prepared by mixing the primary active material of Preparation 2-3 and the third particles of Preparation 1-4 in a weight ratio of about 50:50. The amount of manganese in the first active material was about 55 mol%.

[0221] Example 1-9

[0222] The first active material was prepared by mixing the primary active material of Preparation 2-1 and the third particles of Preparation 1-4 in a weight ratio of about 90:10. The amount of manganese in the first active material was about 60 mol%.

[0223] Example 1-10

[0224] The first active material was prepared by mixing the primary active material of Preparation 2-1 and the third particles of Preparation 1-4 in a weight ratio of about 80:20. The amount of manganese in the first active material was about 60 mol%.

[0225] Example 1-11

[0226] The first active material was prepared by mixing the primary active material of Preparation 2-1 and the third particles of Preparation 1-4 in a weight ratio of about 70:30. The amount of manganese in the first active material was about 60 mol%.

[0227] Example 1-12

[0228] The first active material was prepared by mixing the primary active material of Preparation 2-2 and the third particles of Preparation 1-4 in a weight ratio of about 90: 10. The amount of manganese of the first active material was about 55 mol%.

[0229] Example 1-13

[0230] The first active material was prepared by mixing the primary active material of Preparation 2-2 and the third particles of Preparation 1-4 in a weight ratio of about 80:20. The amount of manganese of the first active material was about 55 mol%.

[0231] Example 1-14

[0232] The first active material was prepared by mixing the primary active material of Preparation 2-2 and the third particles of Preparation 1-4 in a weight ratio of about 70:30. The amount of manganese of the first active material was about 55 mol%.

[0233] Example 2-1: Preparation of second active material

[0234] The second active material was prepared by mixing the first active material of Example 1-9 and the fourth particles of Preparation 1-5 in a weight ratio of about 85: 15.

[0235] Example 2-2

[0236] The second active material was prepared by mixing the first active material of Example 1-9 and the fourth particles of Preparation 1-5 in a weight ratio of about 80:20.

[0237] Example 2-3

[0238] The second active material was prepared by mixing the first active material of Example 1-9 and the fourth particles of Preparation 1-5 in a weight ratio of about 75:25.

[0239] Example 2-4

[0240] The second active material was prepared by mixing the first active material of Example 1-10 and the fourth particles of Preparation 1-5 in a weight ratio of about 85: 15.

[0241] Example 2-5

[0242] The second active material was prepared by mixing the first active material of Example 1-10 and the fourth particles of Preparation 1-5 in a weight ratio of about 80:20.

[0243] Example 2-6

[0244] A second active material was prepared by mixing the first active material of Example 1-10 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 75:25.

[0245] Example 2-7

[0246] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 85:15.

[0247] Example 2-8

[0248] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 80:20.

[0249] Example 2-9

[0250] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 75:25.

[0251] Example 2-10

[0252] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 85:15.

[0253] Example 2-11

[0254] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 80:20.

[0255] Example 2-12

[0256] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 75:25.

[0257] Example 2-13

[0258] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 85:15.

[0259] Example 2-14

[0260] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 80:20.

[0261] Example 2-15

[0262] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 75:25.

[0263] Example 2-16

[0264] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 85:15.

[0265] Example 2-17

[0266] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 80:20.

[0267] Example 2-18

[0268] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 75:25.

[0269] Comparative Example 1

[0270] A second active material was prepared by mixing the first active material of Example 1-9 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 95:5.

[0271] Comparative Example 2

[0272] A second active material was prepared by mixing the first active material of Example 1-9 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 90:10.

[0273] Comparative Example 3

[0274] A second active material was prepared by mixing the first active material of Example 1-9 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 70:30.

[0275] Comparative Example 4

[0276] A second active material was prepared by mixing the first active material of Example 1-9 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 65:35.

[0277] Comparative Example 5

[0278] A second active material was prepared by mixing the first active material of Example 1-10 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 95:5.

[0279] Comparative Example 6

[0280] A second active material was prepared by mixing the first active material of Example 1-10 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 90:10.

[0281] Comparative Example 7

[0282] A second active material was prepared by mixing the first active material of Example 1-10 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 70:30.

[0283] Comparative Example 8

[0284] A second active material was prepared by mixing the first active material of Example 1-10 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 65:35.

[0285] Comparative Example 9

[0286] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 95:5.

[0287] Comparative Example 10

[0288] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 90:10.

[0289] Comparative Example 11

[0290] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 70:30.

[0291] Comparative Example 12

[0292] A second active material was prepared by mixing the first active material of Example 1-11 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 65:35.

[0293] Comparative Example 13

[0294] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 95:5.

[0295] Comparative Example 14

[0296] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 90:10.

[0297] Comparative Example 15

[0298] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 70:30.

[0299] Comparative Example 16

[0300] A second active material was prepared by mixing the first active material of Example 1-12 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 65:35.

[0301] Comparative Example 17

[0302] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 95:5.

[0303] Comparative Example 18

[0304] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 90:10.

[0305] Comparative Example 19

[0306] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 70:30.

[0307] Comparative Example 20

[0308] A second active material was prepared by mixing the first active material of Example 1-13 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 65:35.

[0309] Comparative Example 21

[0310] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth granules of Preparation Example 1-5 in a weight ratio of about 95:5.

[0311] Comparative Example 22

[0312] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth particles of Preparation Example 1-5 in a weight ratio of about 90:10.

[0313] Comparative Example 23

[0314] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth particles of Preparation Example 1-5 in a weight ratio of about 70:30.

[0315] Manufacture of positive electrode

[0316] A second active material was prepared by mixing the first active material of Example 1-14 and the fourth particles of Preparation Example 1-5 in a weight ratio of about 65:35.

[0317] Manufacture of negative electrode

[0318] 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 coated on an aluminum current collector, dried and roll-pressed to manufacture a positive electrode.

[0319] Manufacture of rechargeable lithium battery

[0320] A negative electrode active material slurry was prepared by mixing the Si-graphite composite, a binder, and a conductive material in an N-methylpyrrolidone solvent. The negative electrode active material slurry was coated on a copper current collector, dried and roll-pressed to manufacture a negative electrode.

[0321] Evaluation Example 1: Analysis of surface of positive electrode active material

[0322] A 2032-type coin half-cell was formed using the prepared positive electrode and a lithium metal counter electrode. A separator having a thickness of about 16 µm and consisting of a porous polyethylene (PE) film was disposed between the positive electrode and the lithium metal counter electrode, and an electrolyte was injected to manufacture a rechargeable lithium battery. As the electrolyte, an electrolyte obtained by mixing 1.3 M LiPF6 with a mixed solvent of ethylene carbonate (EC), methyl ethyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of about 3:4:3 was used.

[0323] Figure 10A

[0324] A scanning electron microscope (SEM) image of the first particles prepared in Preparation Example 1-1 (in a single particle form) is shown in Figure 10B An SEM image of the first particles prepared in Preparation Example 1-2 (in a secondary particle form) is shown in Figure 11SEM images of the second particles prepared in Preparation Example 1-3 are shown in Figure 12 SEM images of the third particles prepared in Preparation Example 1-4 are shown in Figure 13 SEM images of the fourth particles prepared in Preparation Example 1-5 are shown in Figure 10A

[0325] Referring to FIG. 1A, Figure 10B It can be seen that the first particles of Preparation Example 1-1 according to the present disclosure have a fine single particle form with nanometer size. Referring to FIG. 1B, Figure 11 It can be seen that the first particles of Preparation Example 1-2 according to the present disclosure have a spherical secondary particle form in which primary particles are aggregated. In addition, it can be seen that the primary particles of Preparation Example 1-2 have a smaller size and are more uniform than the primary particles of Preparation Example 1-1.

[0326] Referring to FIG. 2A, Figure 12 It can be seen that the second particles of Preparation Example 1-3 according to the present disclosure have a secondary particle form in which primary particles are aggregated.

[0327] Referring to FIG. 3A, Figure 13 It can be seen that the third particles of Preparation Example 1-4 according to the present disclosure have a single particle form.

[0328] Referring to FIG. 4A, Evaluation Example 2: Evaluation of positive electrode active material It can be seen that the fourth particles of Preparation Example 1-5 according to the present disclosure have a secondary particle form in which primary particles are aggregated.

[0329] Evaluation Example 3: Battery evaluation

[0330] The positive electrode active materials of Preparation Example 1-2, Examples 1-1 to 2-18, and Comparative Examples 1 to 24 were used to measure the powder density (PD), and the results are shown in Tables 1 and 2 below. The powder density was measured by placing 3 g of the positive electrode active material in a powder compaction mold and applying a force of about 4.0 US tons for about 30 seconds.

[0331] ​

[0332] The properties of rechargeable lithium batteries manufactured using the positive electrode active materials of Preparation Example 1-2, Examples 1-1 to 2-18, and Comparative Examples 1 to 24 were evaluated, and the results are shown in Tables 1 and 2 below.

[0333] ​The rechargeable lithium battery was initially charged at a constant current (about 0.2C) and a constant voltage (about 4.25V, cutoff current: about 0.01C) and, after resting for about 10 minutes, discharged at a constant current (about 0.2C) to a cutoff voltage of about 2.5V to perform initial charging and discharging, thereby obtaining an initial discharge capacity (0.2C discharge) and an initial charge capacity (0.2C charge), and an efficiency (0.2C efficiency) was expressed as the initial discharge capacity / initial charge capacity. Then, charging and discharging were repeated 50 times under the same conditions (charge: about 0.2C to 4.25V, cutoff current: about 0.01C; discharge: about 0.2C to 2.5V), and a lifespan (%) was expressed as a discharge capacity after the 50th cycle / initial discharge capacity. The average voltage was obtained by integrating the area under the discharge voltage curve (voltage-capacity graph) after the initial charging and discharging of the battery cell, and then dividing the integral by the discharge capacity. The powder compaction density was measured by putting 3 grams of the positive electrode active material into a powder compaction jig and applying a force of about 4.0 metric tons for about 30 seconds. The results of the evaluation of the battery properties are shown in Tables 1 and 2 below.

[0334] Table 1

[0335]

[0336]

[0337] Table 2

[0338]

[0339]

[0340]

[0341] Referring to Table 1, it can be seen that the rechargeable lithium battery including the first active material according to Examples 1-1 to 1-14 has a higher average voltage, a higher lifespan characteristic, a higher powder compaction density, and substantially the same or better energy density compared to the rechargeable lithium battery including only the first particle PTC1 of Preparation Example 1-1. That is, it can be seen that the first active material can improve the average voltage, the lifespan characteristic, and the energy density while having economic feasibility within the mixed weight ratio and the manganese content range of the examples in Table 1. Referring to Table 2, it can be seen that the rechargeable lithium battery including the second active material according to Examples 2-1 to 2-3 of the present disclosure has a higher lifespan characteristic, the same or better powder compaction density, and better energy density compared to the rechargeable lithium battery including the positive electrode active material according to Comparative Examples 1 to 4. Since the efficiency property is lower than the efficiency of a common negative electrode, it can be seen that Comparative Examples 3 and 4 correspond to a portion for which the purpose of mixing is inhibited.

[0342] Referring to Table 2, it can be seen that the rechargeable lithium battery including the second active material according to Examples 2-4 to 2-6 has the same or better powder compaction density and similar or better energy density compared to the rechargeable lithium battery including the positive electrode active material according to Comparative Examples 5 to 8. Since the efficiency property is lower than the efficiency of a common negative electrode, it can be seen that Comparative Examples 7 and 8 correspond to a portion for suppressing mixing.

[0343] Referring to Table 2, it can be seen that the rechargeable lithium battery including the second active material according to Examples 2-7 to 2-9 has higher life characteristics, the same or better powder compaction density, and similar or better energy density compared to the rechargeable lithium battery including the positive electrode active material according to Comparative Examples 9 to 12. Since the efficiency property is lower than the efficiency of a common negative electrode, it can be seen that Comparative Examples 11 and 12 correspond to a portion for suppressing mixing.

[0344] Referring to Table 2, it can be seen that the rechargeable lithium battery including the second active material according to Examples 2-10 to 2-12 has higher life characteristics, the same or better powder compaction density, and similar or better energy density compared to the rechargeable lithium battery including the positive electrode active material according to Comparative Examples 13 to 16. Since the efficiency property is lower than the efficiency of a common negative electrode, it can be seen that Comparative Examples 15 and 16 correspond to a portion for suppressing mixing.

[0345] Referring to Table 2, it can be seen that the rechargeable lithium battery including the second active material according to Examples 2-13 to 2-15 has higher life characteristics, the same or better powder compaction density, and similar or better energy density compared to the rechargeable lithium battery including the positive electrode active material according to Comparative Examples 17 to 20. Since the efficiency property is lower than the efficiency of a common negative electrode, it can be seen that Comparative Examples 19 and 20 correspond to a portion for suppressing mixing.

[0346] Referring to Table 2, it can be seen that the rechargeable lithium battery including the second active material according to Examples 2-16 to 2-18 has higher life characteristics, the same or better powder compaction density, and similar or better energy density compared to the rechargeable lithium battery including the positive electrode active material according to Comparative Examples 21 to 24. Since the efficiency property is lower than the efficiency of a common negative electrode, it can be seen that Comparative Examples 23 and 24 correspond to a portion for suppressing mixing.

[0347] Summarizing the results in Table 2, within the mixing weight ratio and manganese content range of the examples in Table 2, the second active material according to Examples 2-1 to 2-18 of the present disclosure can improve capacity and energy density properties while minimizing the efficiency deterioration of the second active material.

[0348] By including first particles having an olivine structure, the positive electrode active material according to the present disclosure may exhibit improved economic feasibility, structural stability, and energy density.

[0349] By including the second particles having the spinel structure, the positive electrode active material according to the present disclosure may exhibit improved average voltage and lifespan characteristics.

[0350] By including the third particles having a layered structure, the positive electrode active material according to the present disclosure may exhibit improved lifespan characteristics and energy density.

[0351] The positive electrode active material according to the present disclosure may further include fourth particles, and accordingly, capacity and energy density may be further improved.

[0352] By mixing the first, second, and third particles in appropriate proportions, the positive electrode active material according to the present disclosure can have improved energy density, average voltage, and lifespan characteristics while ensuring economic feasibility. Moreover, if the fourth particle is additionally included, the capacity and energy density can be further improved.

[0353] Although the embodiments of the present disclosure have been described, it should be understood that the present disclosure should not be limited to these embodiments. Instead, those skilled in the art can make various changes and modifications within the spirit and scope of the present disclosure.

Claims

1. A positive electrode active material comprising: first particles comprising a compound of Chemical Formula 1 and having an olivine structure; second particles comprising a compound of Chemical Formula 2 and having a spinel structure; and third particles comprising a compound of Chemical Formula 3 and having a layered structure, wherein the amount of the third particles is about 10 parts by weight to about 50 parts by weight based on 100 parts by weight of the positive electrode active material: wherein Chemical Formula 1 is: wherein 0.8 < al < 1.2, 0.4 < xl < 0.8, 0.15 < yl < 0.6, 0 < zl < 0.05, 0 < cl < 0.05, xl + yl + zl = 1, and wherein A is at least one of Al, Ti, V, and Mg, Li a1 Mn x1 Fe y1 A z1 PO 4-c1 wherein Chemical Formula 2 is: wherein 0.8 < a2 < 1.2, 1.9 < x2 < 2.05, 0 < y2 < 0.05, 0 < c2 < 0.05, and wherein B is at least one of Al and Mg, and Li a2 Mn x2 B y2 O 4-c2 wherein Chemical Formula 3 is: wherein 0.8 < a3 < 1.2, 0.5 < x3 < 0.8, 0 < y3 < 0.10, 0.1 < z3 < 0.35, 0 < wl < 0.1, 0 < c3 < 0.05, and E is at least one of Al, Ti, Mg, Zr, Mo, and Nb. Li a3 Ni x3 Co y3 Mn z3 E w1 O 2-c3 2. The positive electrode active material of claim 1, further comprising fourth particles comprising a compound of Chemical Formula 4: wherein 1.1 < a4 < 1.6, 0.2 < x4 < 0.5, 0.5 < y4 < 0.8, 0 < z4 < 0.05, 2 < c4 < 2.3, and wherein D is at least one transition metal having an oxidation number of 4. Li a4 Ni x4 Mn y4 D z4 O c4 3. The positive electrode active material of claim 2, wherein the amount of the fourth particles is 15 parts by weight to 25 parts by weight based on 100 parts by weight of the positive electrode active material.

4. The positive electrode active material of claim 2, wherein the first particles, the second particles, and the third particles constitute a first active material, wherein the first particles, the second particles, the third particles, and the fourth particles constitute a second active material, wherein the amount of manganese in the first active material is 50 mol% to 80 mol%, and wherein the amount of manganese in the second active material is 50 mol% to 60 mol%.

5. The positive electrode active material of claim 2, wherein the average diameter of the fourth particles is 5 μm to 10 μm.

6. The positive electrode active material of claim 4, wherein the amount of the third particles is 30 parts by weight to 50 parts by weight based on 100 parts by weight of the first active material.

7. The positive electrode active material of claim 1, wherein the first particles and the second particles constitute a main active material, wherein the first particles, the second particles, and the third particles constitute a first active material, and wherein the amount of the main active material is 50 parts by weight to 85 parts by weight based on 100 parts by weight of the first active material. ​ 8. The positive electrode active material of claim 1, wherein the amount of manganese in the positive electrode active material is 50 mol% to 70 mol%.

9. The positive electrode active material of claim 1, wherein the first particles and the second particles constitute a main active material, and a mixing ratio of the first particles to the second particles in the main active material is 40:60 to 65:35 based on weight.

10. The positive electrode active material of claim 1, wherein the first particles have a single particle form, and an average diameter of the first particles is 0.5 μm to 2.5 μm.

11. The positive electrode active material of claim 1, wherein the first particles have a secondary particle form in which a plurality of first primary particles are aggregated, an average diameter of the first particles is 3 μm to 10 μm, and an average diameter of the first primary particles is 50 nm to 150 nm.

12. The positive electrode active material of claim 1, wherein an average diameter of the second particles is 3 μm to 10 μm.

13. The positive electrode active material of claim 1, wherein a porosity of the first particles is 20% to 40%.

14. The positive electrode active material of claim 1, wherein a span value of the first particles is 0.3 to 0.

75.

15. A positive electrode for a rechargeable lithium battery, the positive electrode comprising: a positive electrode current collector; and a positive electrode active material layer on the positive electrode current collector, wherein the positive electrode active material layer comprises the positive electrode active material according to any one of claims 1 to 14, a conductive material, and a binder.

16. The positive electrode for a rechargeable lithium battery of claim 15, wherein an amount of the binder is 0.5 parts by weight to 5 parts by weight based on 100 parts by weight of the positive electrode active material layer.

17. The positive electrode for a rechargeable lithium battery of claim 15, wherein the binder comprises at least one of polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, an oxirane-containing polymer, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, an epoxy resin, a (meth)acrylic resin, a polyester resin, and nylon.

18. The positive electrode for a rechargeable lithium battery of claim 15, wherein an amount 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.

19. The positive electrode for a rechargeable lithium battery of claim 15, wherein the conductive material comprises a carbon-based material, a metal-based material having a form of a metal powder or a metal fiber, a conductive polymer, or a mixture thereof.

20. A rechargeable lithium battery, comprising: the positive electrode according to any one of claims 15 to 19; a negative electrode comprising 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. a separator between the positive electrode and the negative electrode.

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