Positive electrode active material, method of manufacturing same, positive electrode including positive electrode active material, and rechargeable lithium battery including positive electrode

Abstract

The application relates to a positive electrode active material, a method of manufacturing the same, a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode. A rechargeable lithium battery may include a positive electrode active material. The positive electrode active material includes: first particles including a first lithium composite oxide and having a first average particle diameter; and a second particle including a second lithium composite oxide and having a second average particle diameter greater than the first average particle diameter. The first particle includes yttrium (Y) and zirconium (Zr) on a surface of the first particle. Yttrium (Y) on the surface of the first particles has a first composition. Yttrium (Y) on the surface of the second particles has a second composition. The ratio of the first composition to the second composition is greater than about 100.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10 - 2023 - 0177463, filed with the Korean Intellectual Property Office on December 8, 2023, the entire contents of which are incorporated herein by reference. Technical field

[0003] Embodiments of the present disclosure described herein relate to a positive electrode active material, a method of manufacturing a positive electrode active material, a positive electrode including the positive electrode active material, and a rechargeable lithium battery including the positive electrode. Background art

[0004] When there is no AC (alternating current) power source available to supply power to a building, or when a DC (direct current) power source is desired or required, a battery that generates electrical energy through a physical or chemical reaction and supplies the generated electrical energy to the outside is used according to the living or usage environment surrounded by one or more appropriate electrical and / or electronic devices.

[0005] In such batteries, primary batteries (using chemical reactions) and secondary batteries are generally used. A primary battery (or non - rechargeable battery) is a consumable battery, collectively referred to as a dry battery. In contrast, a secondary battery (e.g., a rechargeable battery) is a rechargeable battery in which oxidation and reduction reactions are repeated at the positive electrode and the negative electrode.

[0006] Lithium composite oxides containing a relatively high nickel content as positive electrode active materials for rechargeable lithium batteries have attracted considerable attention. The positive electrode active material has the advantage of relatively high energy density. Interest in rechargeable lithium batteries with relatively high capacity can induce, cause, or encourage the use of a bimodal type or kind of positive electrode active material, which includes a mixture of small particles and large particles having different average particle sizes from each other. Summary of the invention

[0007] Aspects according to one or more embodiments relate to a positive electrode active material having a relatively high ionic conductivity for a rechargeable lithium battery.

[0008] Aspects according to one or more embodiments relate to a rechargeable lithium battery having increased stability and capacity retention properties.

[0009] Additional aspects will be set forth in part in the following description and in part will be obvious from the description, or may be learned by practice of the embodiments presented in the present disclosure.

[0010] According to one or more embodiments of the present disclosure, the positive electrode active material may include: first particles including a first lithium composite oxide and having a first average particle diameter (e.g., a plurality of first particles, each including a first lithium composite oxide and having a first average particle diameter); and second particles including a second lithium composite oxide and having a second average particle diameter greater than the first average particle diameter (e.g., a plurality of second particles, each including a second lithium composite oxide and having a second average particle diameter greater than the first average particle diameter). The first particles may include yttrium (Y) and zirconium (Zr) on the surface of the first particles. The yttrium (Y) on the surface of the first particles may have a first composition. The yttrium (Y) on the surface of the second particles may have a second composition. The ratio of the first composition to the second composition may be greater than about 100.

[0011] According to one or more embodiments of the present disclosure, a method of manufacturing a positive electrode active material may include: synthesizing first particles including a first lithium composite oxide and having a first average particle diameter (e.g., a plurality of first particles each including a first lithium composite oxide and having a first average particle diameter); synthesizing second particles including a second lithium composite oxide and having a second average particle diameter greater than the first average particle diameter (e.g., a plurality of second particles each including a second lithium composite oxide and having a second average particle diameter greater than the first average particle diameter); and mixing the first particles and the second particles with each other. The step of synthesizing the first particles (e.g., an action or task) may include: preparing a precursor of the first particles; and firing the precursor together with a flux. The flux may include yttrium (Y) and zirconium (Zr).

[0012] According to one or more embodiments of the present disclosure, a positive electrode for a rechargeable lithium battery may include the positive electrode active material discussed herein.

[0013] According to one or more embodiments of the present disclosure, a rechargeable lithium battery may include the positive electrode discussed herein. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 A simplified conceptual diagram showing a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated.

[0015] Figure 2 A diagram showing a positive electrode active material according to one or more embodiments of the present disclosure is illustrated.

[0016] Figure 3 A flowchart showing a method of manufacturing a positive electrode active material according to one or more embodiments of the present disclosure is illustrated.

[0017] Figures 4 to 6 Illustrates showing Figure 3 A simplified diagram of a method of manufacturing a positive electrode active material.

[0018] Figure 7 Illustrates a perspective view of a rechargeable lithium battery showing one or more embodiments according to the present disclosure.

[0019] Figure 8A and Figure 8B Illustrates a graph showing the SEM-EDS analysis results of the first particles of Embodiment 1.

[0020] Figure 9A and Figure 9B Illustrates a graph showing the SEM-EDS analysis results of the second particles of Embodiment 1. Detailed Description

[0021] To fully understand the configuration and aspects of the present disclosure, one or more 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 one or more suitable forms. Instead, the exemplary embodiments are provided only to disclose the present disclosure and enable those skilled in the art to fully understand the scope of the present disclosure.

[0022] In this description, it will be understood that if (e.g., when) one element is referred to as being on another element, the element can be directly on the other element or there can be intervening elements therebetween. In the drawings, the thickness of some components is enlarged to effectively explain the technical content. The same reference numerals refer to the same elements throughout, and repeated descriptions thereof may not be provided in the specification.

[0023] Some embodiments detailed in this description will be discussed with reference to cross-sectional views and / or plan views that are exemplary views of the present disclosure. In the drawings, the thickness of layers and regions is enlarged to effectively explain the technical content. Accordingly, the regions illustrated in the drawings have a general nature, and the shapes of the regions illustrated in the drawings are used to disclose specific shapes but are not limited to the scope of the present disclosure. It will be understood that although terms such as "first", "second", "third", etc. may be used herein to describe one or more suitable elements, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. One or more embodiments explained and illustrated herein include their complementary embodiments.

[0024] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms are also intended to include the plural forms. The terms "comprises" / "includes" and / or "comprising" / "including" used in this specification do not exclude the presence or addition of one or more other components.

[0025] In this document, it should be understood that terms such as "comprising", "including" or "having" are intended to indicate the presence of embodied aspects, quantities, operations, elements and / or combinations thereof (e.g., any suitable combination), but do not exclude the possibility of the presence or addition of one or more other features, quantities, operations, elements and / or combinations thereof (e.g., any suitable combination).

[0026] As used herein, expressions such as "at least one of...", "one of...", and "selected from...", when before / after a list of elements, modify the entire list of elements and not individual elements of the list. For example, "at least one of a, b, and c", "at least one selected from a, b, and c", etc. may indicate only a, only b, only c, both a and b (e.g., simultaneously), both a and c (e.g., simultaneously), both b and c (e.g., simultaneously), all of a, b, and c, or variations thereof.

[0027] In the drawings, for clarity, the thickness of layers, films, panels, regions, etc. is exaggerated, and the same reference numerals throughout the drawings denote the same elements, and repeated descriptions thereof may not be provided in the specification. It will be understood that if (e.g., when) an element (such as a layer, film, region, or substrate) is referred to as being "on" another element (such as a layer, film, region, or substrate), it may be directly on the other element (such as a layer, film, region, or substrate) or there may also be intervening elements. In other embodiments, if (e.g., when) an element (such as a layer, film, region, or substrate) is referred to as being "directly on" another element (such as a layer, film, region, or substrate), then there are no intervening elements.

[0028] In one or more embodiments, a "layer" herein includes not only a shape formed over an entire surface if (e.g., when) viewed in a plan view, but also a shape formed over a partial surface.

[0029] "Group" refers to a group of the periodic table according to the group sub - system of Groups 1 - 18 of the International Union of Pure and Applied Chemistry ("IUPAC").

[0030] In this document, "or" is not interpreted in an exclusive sense. For example, "A or B" should be interpreted to include A, B, A + B, etc.

[0031] "Metal" is interpreted to include the concepts of common metals, transition metals, and metalloids (semi - metals).

[0032] As used herein, the terms "substantially" and similar terms are used as approximate terms and not as terms of degree, and are intended to account for the inherent deviations of measured or calculated values that would be recognized by a person of ordinary skill in the art. Also, the terms "about" and similar terms, when used herein in connection with a numerical value or numerical range, include the recited value and values within an acceptable deviation range of the recited value as determined in view of the measurements discussed and the errors associated with the measurement of a particular quantity (i.e., the limitations of the measurement system). For example, "about" can mean within one or more standard deviations, or within ±30%, ±20%, ±10%, or ±5% of the recited value.

[0033] Also, any numerical range recited herein is intended to include all sub-ranges of the same numerical precision subsumed within the recited range. For example, the range "1.0 to 10.0" is intended to include all sub-ranges (and including the recited minimum value of 1.0 and the recited maximum value of 10.0) between the recited minimum value of 1.0 and the recited maximum value of 10.0, that is, having a minimum value equal to or greater than 1.0 and a maximum value equal to or less than 10.0, such as, for example, 2.4 to 7.6. Any maximum numerical limitation recited herein is intended to include all lower numerical limitations subsumed therein, and any minimum numerical limitation recited in this specification is intended to include all higher numerical limitations subsumed therein. Accordingly, the applicant reserves the right to amend this specification (including the claims) to expressly recite any sub-ranges subsumed within the ranges expressly recited herein.

[0034] Hereinafter, the positive electrode active material and the rechargeable lithium battery according to one or more exemplary embodiments will be described in more detail.

[0035] Figure 1 A simplified conceptual diagram showing a rechargeable lithium battery according to one or more embodiments of the present disclosure is illustrated. Refer Figure 1 , the rechargeable lithium battery may include a positive electrode 100, a negative electrode 200, an electrolyte 300, and a separator 400.

[0036] The positive electrode 100 and the negative electrode 200 may be spaced apart and / or separated from each other across the separator 400 (e.g., spaced apart or separated). The separator 400 may be disposed between the positive electrode 100 and the negative electrode 200. The positive electrode 100, the negative electrode 200, and the separator 400 may be in contact with the electrolyte 300. The positive electrode 100, the negative electrode 200, and the separator 400 may be impregnated in the electrolyte 300.

[0037] The electrolyte 300 may be a medium for the transfer of lithium ions between the positive electrode 100 and the negative electrode 200. The lithium ions in the electrolyte 300 may move through the separator 400 toward the positive electrode 100 or the negative electrode 200.

[0038] The positive electrode 100 may include a first current collector COL1 and a positive electrode active material layer AML1 on the first current collector COL1. The first current collector COL1 may include a metal (such as one or more of aluminum, copper, nickel-plated copper, stainless steel, nickel, titanium, palladium, and aluminum-cadmium alloy). The first current collector COL1 may include a polymer substrate having a metal disposed (e.g., coated or deposited) on at least one surface of the polymer substrate. The first current collector COL1 may be formed into a film, sheet, foil, grid, mesh, porous material, foam, or non-woven fabric.

[0039] The positive electrode active material layer AML1 may include a binder, a conductive material, and a positive electrode active material. Based on the total weight of the positive electrode active material layer AML1, the amount of the positive electrode active material may be about 80 wt% to about 99 wt%, for example, about 85 wt% to about 98 wt%. The positive electrode active material may be a lithium ion source. The positive electrode active material may be a lithium composite oxide that includes not only lithium but also at least one transition metal. Reference will be made Figure 2 to a more detailed description of the positive electrode active material according to one or more embodiments of the present disclosure.

[0040] The conductive material may provide conductivity to the positive electrode active material layer AML1. The conductive material may include at least one selected from carbon-based materials (e.g., graphite, carbon black, acetylene black, Ketjen black, furnace black, lamp black, thermal black, and carbon fiber), metal powders, metal fibers, conductive whiskers, conductive metal oxides, conductive polymers, and combinations thereof (e.g., any suitable combination). Based on the total weight of the positive electrode active material layer AML1, the amount of the conductive material may be about 1 wt% to about 30 wt%.

[0041] The binder may increase the adhesion between the positive electrode active material and the first current collector COL1. For example, the binder may include at least one selected from polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and combinations thereof (e.g., any suitable combination). Based on the total weight of the positive electrode active material layer AML1, the amount of the binder may be about 1 wt% to about 30 wt%.

[0042] The negative electrode 200 may include a second current collector COL2 and a negative electrode active material layer AML2 on the second current collector COL2. The description of the second current collector COL2 may be the same as or similar to the description of the first current collector COL1. The second current collector COL2 may include a metal that is the same as or different from the metal of the first current collector COL1. The second current collector COL2 may have a shape that is the same as or different from the shape of the first current collector COL1.

[0043] The negative electrode active material layer AML2 may include a binder, a conductive material, and a negative electrode active material. The binder and the conductive material may be the same as the binder and the conductive material discussed above in the positive electrode active material layer AML1. Based on the total weight of the negative electrode active material layer AML2, the amount of the negative electrode active material may be about 80 wt% to about 99 wt%, for example, about 85 wt% to about 98 wt%. The negative electrode active material may include at least one selected from the group consisting of carbonaceous materials, lithium metal, lithium metal compounds, silicon, silicon compounds, tin, and tin compounds. Metal oxides having a potential less than about 2V (such as TiO 2 or SnO 2 ) can also be used as the negative electrode active material. The carbonaceous material may include one or more of low-crystalline carbon and high-crystalline carbon.

[0044] The separator 400 may include a porous polymer film formed of a polyolefin polymer (such as ethylene homopolymer, propylene homopolymer, ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-methyl acrylate copolymer). The separator 400 may include a single layer of the porous polymer film or a stacked material of multiple porous polymer films. In one or more embodiments of the present disclosure, the separator 400 may include a common porous non-woven fabric (such as high-melting-point glass fiber or polyethylene terephthalate fiber).

[0045] The electrolyte 300 may include a salt having an A + B - structure. A + may include at least one alkali metal cation selected from the group consisting of Li + , Na + , and K + . B - may include at least one selected from the group consisting of F - , Cl - , Br - , I - , NO 3 - , N(CN) 2 - , BF 4 - , ClO 4 - , AlO 4- 、AlCl 4 - 、PF 6 - 、SbF 6 - 、AsF 6 -、BF 2 C 2 O 4 - 、BC 4 O 8 - 、(CF 3 ) 2 PF 4 - 、(CF 3 ) 3 PF 3 - 、(CF 3 ) 4 PF 2 - 、(CF 3 ) 5 PF - 、(CF 3 ) 6 P - 、CF 3 SO 3 - 、C 4 F 9 SO 3 - 、CF 3 CF 2 SO 3 - 、(CF 3 SO 2 ) 2 N - 、(FSO 2 ) 2 N - 、CF 3 CF 2 (CF 3 ) 2 CO - 、(CF 3 SO 2 ) 2 CH - 、(SF 5 ) 3 C - 、(CF 3 SO 2 ) 3 C - 、CF3 (CF 2 ) 7 SO 3 - CF 3 CO 2 - , CH 3 CO 2 - 、SCN - and (CF 3 CF 2 SO 2 ) 2 N - At least one anion.

[0046] In one or more embodiments of the present disclosure, the electrolyte 300 can be used by dissolving a salt in an organic solvent. The organic solvent may include propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide (DMSO), acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone (NMP), ethyl methyl carbonate (EMC), γ-butyrolactone or any mixture thereof.

[0047] A housing commonly used in the art may be used as the housing of the rechargeable lithium battery according to one or more embodiments of the present disclosure, and there may be no limitation on the appearance according to the use of the battery. For example, the housing of the rechargeable lithium battery may have a cylindrical shape, a prismatic shape, a bag shape, or a coin shape.

[0048] Figure 2 A diagram showing a positive electrode active material according to one or more embodiments of the present disclosure is illustrated. Figure 2 , the positive electrode active material CAM may include the above reference Figure 1 The powder before the positive electrode active material layer AML1 discussed above (for example, can be used for Figure 1 The positive electrode active material layer AML1 discussed above is provided in the form of a powder. The positive electrode active material CAM may include a plurality of first particles PTC1, a plurality of second particles PTC2, and a plurality of aggregates ZAG.

[0049] The first particles PTC1 (e.g., a plurality of first particles) may have a first average particle diameter APD1, and the second particles PTC2 (e.g., a plurality of second particles) may have a second average particle diameter APD2. The first average particle diameter APD1 may be less than the second average particle diameter APD2. For example, the first average particle diameter APD1 may be in the range of about 1 μm to about 5 μm. The second average particle diameter APD2 may be in the range of about 10 μm to about 25 μm. The term "average particle diameter" or D50 used in the present disclosure may refer to the particle diameter when the volume cumulative percentage corresponds to about 50% in the particle size distribution obtained from a certain volume of particles (e.g., when). The average particle diameter can be measured by any suitable method used in the art, and can be evaluated, for example, by a particle size analyzer, a transmission electron microscope image, or a scanning electron microscope image. In one or more embodiments, the average particle diameter value can be obtained by: using the dynamic light scattering method, performing data analysis to count the number of particles in each particle size range, and calculating the average particle diameter value from the results. Unless otherwise defined, the average particle diameter (D50) may refer to the diameter of the particles with a cumulative volume of about 50% by volume in the particle size distribution. In one or more embodiments, the particle size distribution can be obtained by measuring the sizes (e.g., diameter or major axis length) of approximately 12 particles randomly selected from a transmission electron microscope image, and then, unless otherwise indicated, the diameter of the particles with a cumulative volume of 50% by volume in the particle size distribution can be referred to as the average particle diameter (D50). In the present disclosure, the first particles PTC1 may be referred to as small particles, and the second particles PTC2 may be referred to as large particles.

[0050] The first particles PTC1 and the second particles PTC2 may be granular or spherical.

[0051] In one or more embodiments of the present disclosure, the first particles PTC1 may be formed into single particles (e.g., each of the first particles is a single particle or an integral particle). In this description, the term "single particle" may refer to an individual single particle that has no grain boundaries (e.g., there are no grain boundaries inside a single particle), and is an integral structure in which the particles do not aggregate with each other (e.g., there is no agglomeration), but exist as an independent phase morphologically, and thus can be represented as a single crystal particle (e.g., a single particle is not in the form of secondary particles). In one or more embodiments, a single particle may be a particle containing several crystals. The single particles can be provided in a single separated form, or can exist in a form in which less than 10 single particles are bonded to each other. The second particles PTC2 may (e.g., each of the second particles may) be formed into or formed as secondary particles in which primary particles aggregate (e.g., agglomerate) (e.g., the secondary particles are not in the form of single particles).

[0052] The positive electrode active material CAM according to one or more embodiments of the present disclosure may have a bimodal type or species including small particles (e.g., PTC1) and large particles (e.g., PTC2) having different average particle sizes. The small particles may fill the pores between the large particles, so that the positive electrode active material CAM may have an increased packing density. For example, the positive electrode active material CAM according to one or more embodiments of the present disclosure may have a high energy density per unit volume.

[0053] In one or more embodiments, the first particles PTC1 and the second particles PTC2 in the positive electrode active material CAM may have a weight ratio of about 95:5 to about 50:50. In one or more embodiments, the first particles PTC1 and the second particles PTC2 in the positive electrode active material CAM may have a weight ratio of about 5:95 to about 50:50. For example, in the positive electrode active material CAM, the weight of the second particles PTC2 may be greater than the weight of the first particles PTC1. Each of the first lithium composite oxide and the second lithium composite oxide may include nickel (Ni). Each of the first lithium composite oxide and the second lithium composite oxide may further include at least one metal selected from cobalt (Co), manganese (Mn), and aluminum (Al).

[0054] For example, the first lithium composite oxide may be represented by Chemical Formula 1.

[0055] [Chemical Formula 1]

[0056] Li a1 Ni x1 Ma 1-x1 Zr w1 Y c1 O b1

[0057] In Chemical Formula 1, the range of the subscript “a1” may be about 0.5 to about 1.5, the range of the subscript “x1” may be about 0.6 to about 0.99, the range of the subscript “b1” may be about 1.8 to about 2.2, the range of the subscript “1-x1” may be 0.01 to about 0.4, the range of the subscript “w1” may be about 0.0005 to about 0.003, and the range of the subscript “c1” may be about 0.00002 to about 0.0003 (0.00002 ≤ c1 ≤ 0.0003). The symbol Ma may include at least one element selected from Co, Al, Mn, Na, Mg, Ca, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, and Sn. In one or more embodiments, the symbol Ma may include Co, Al, and Mn.

[0058] The second lithium composite oxide may be represented by Chemical Formula 2.

[0059] [Chemical Formula 2]

[0060] Li a2 Ni x2 Mb 1-x2 O b2

[0061] In Chemical Formula 2, the subscript “a2” can range from about 0.5 to about 1.5, the subscript “x2” can range from about 0.6 to about 0.99, the subscript “b2” can range from about 1.8 to about 2.2, and the subscript “1 - x2” can range from 0.01 to about 0.4. The symbol Mb can include at least one element selected from Co, Al, Mn, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Zr, and Sn. In one or more embodiments, the symbol Mb can include Co, Al, and Mn. In the present disclosure, transition metals can include post-transition metals (such as Al).

[0062] For example, the second lithium composite oxide can be represented by Chemical Formula 2-1.

[0063] [Chemical Formula 2-1]

[0064] Li a2 Ni x2 Zr w2 Mb 1-x2-w2 O b2

[0065] In Chemical Formula 2-1, the subscript “a2” can range from about 0.5 to about 1.5, the subscript “x2” can range from about 0.6 to about 0.99, the subscript “b2” can range from about 1.8 to about 2.2, the subscript “w2” can range from about 0.001 to about 0.4, and the subscript “1 - x2 - w2” can range from about 0.009 to about 0.399. The symbol Mb can include at least one element selected from Co, Al, Mn, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Zr, and Sn. In one or more embodiments, the symbol Mb can include Co, Al, and Mn. In the present disclosure, transition metals can include post-transition metals (such as Al).

[0066] The symbols Mb of the second lithium composite oxide and the ratios of the elements included in Mb may be different from the symbols Ma of the first lithium composite oxide and the ratios of the elements included in Ma. For example, the symbol Mb of the second lithium composite oxide may include Co and Al, and the symbol Ma of the first lithium composite oxide may include Co and Mn. As another example, each of the symbol Ma and the symbol Mb may include Co, Al, and Mn. The composition ratio of Al in the symbol Ma may be greater than the composition ratio of Al in the symbol Mb, and the composition ratio of Mn in the symbol Ma may be less than the composition ratio of Mn in the symbol Mb.

[0067] As Figure 2 disclosed in, the first particle PTC1 may include doped particles on its surface. The doped particles may include yttrium (Y) and zirconium (Zr). For example, the first particle PTC1 according to the present disclosure may include yttrium (Y) and zirconium (Zr) on its surface. The yttrium (Y) and zirconium (Zr) included on the surface of the first particle PTC1 may be derived from a flux that will be discussed in more detail. In one or more embodiments of the present disclosure, the flux may be yttria-stabilized zirconia (YSZ).

[0068] The terms "composition of yttrium (Y)" or "composition of zirconium (Zr)" used in this description may be obtained from the results of analyzing the elements on the surface of the positive electrode active material CAM by using energy dispersive spectroscopy (EDX) or scanning electron microscope energy dispersive spectroscopy (SEM-EDS). The elements on the surface of the positive electrode active material CAM that collide with the electron beam may be configured to emit characteristic X-rays. The emitted characteristic X-rays may be analyzed by an EDX detector to determine the types and amounts of the corresponding elements.

[0069] The term "composition" used in the present disclosure may refer to the amount (weight) of an element included in a specific compound. The term "composition ratio" used in the present disclosure may indicate the ratio (weight ratio) of an element included in a specific compound.

[0070] The yttrium (Y) on the surface of the first particle PTC1 may have a first composition, and the yttrium (Y) on the surface of the second particle PTC2 may have a second composition.

[0071] According to the method of manufacturing the positive electrode active material described subsequently, a small amount of yttrium (Y) on the surface of the second particle PTC2 may be detected after the process of mixing the first particle PTC1 and the second particle PTC2 with each other. According to the present disclosure, the mixing process may result in the presence of an extremely small amount of yttrium (Y) on the surface of the second particle PTC2 (for example, there is no yttrium on the surface of the second particle PTC2), and thus it can be seen that yttrium (Y) is not (or substantially not) provided on the surface of the second particle PTC2 (for example, there is substantially no yttrium) (for example, there is no yttrium on the surface of the second particle PTC2).

[0072] In the present disclosure, the ratio of the first component to the second component may be greater than about 100. For example, the range of the ratio of the first component to the second component may be from about 100 to about 100,000. The ratio of the first component to the second component may have no upper limit. In the present disclosure, the compositional ratio of yttrium (Y) present on the surface of the small particles may be much greater than the compositional ratio of yttrium (Y) present on the surface of the large particles.

[0073] The surface of the first PTC particle PTC1 may have a compositional ratio of yttrium to zirconium (Y / Zr). The range of the compositional ratio (Y / Zr) may be from about 0.5 to about 20. In one or more embodiments, the doped particles on the surface of the first PTC particle PTC1 may have a compositional ratio of yttrium to zirconium (Y / Zr).

[0074] When the compositional ratio (Y / Zr) has the range discussed above, the ionic conductivity of the rechargeable lithium battery can be effectively improved.

[0075] In one or more embodiments of the present disclosure, the subscript "x1" or the molar ratio of Ni in Chemical Formula 1 may be greater than about 0.8. When the first lithium composite oxide has a composition (having a high Ni composition (x1 > 0.8)), the first lithium composite oxide can be fired at a low temperature. Therefore, in the method for manufacturing a positive electrode active material for a rechargeable lithium battery described below, the first PTC particle PTC1 can be synthesized at a low temperature. Ni in the first lithium composite oxide can affect the power and capacity of the rechargeable lithium battery. In the present disclosure, the first lithium composite oxide having a high nickel composition can be used to provide a high-power rechargeable lithium battery. The subscript "x2" or the molar ratio of Ni in Chemical Formula 2 may also be greater than about 0.8. However, the subscript "x2" may be different from the subscript "x1".

[0076] An increase in the amount of Ni in the first lithium composite oxide and the second lithium composite oxide may lead to a decrease in the stability of the positive electrode or the rechargeable battery. In one or more embodiments of the present disclosure, the first lithium composite oxide and the second lithium composite oxide may further include Co, and thus the stability and capacity retention properties of the rechargeable battery can be improved.

[0077] According to one or more embodiments of the present disclosure, the first PTC particle PTC1 can be formed into a single particle. The first PTC particle PTC1 may be denser and more durable than the second PTC particle PTC2. Therefore, microcracks in the first PTC particle PTC1 can be prevented or reduced. As a result, the stability and capacity retention properties of the rechargeable battery according to the present disclosure can be improved.

[0078] To form the first lithium composite oxide, the first particulate PTC1 formed as a single particle may undergo a firing process at a temperature of less than about 1,000 °C. In this case, the amount of residual lithium on the surface of the first particulate PTC1 may increase, and thus the ionic conductivity on the surface of the first particulate PTC1 may decrease. Accordingly, the power and capacity retention properties of the rechargeable battery may be reduced to some extent.

[0079] As discussed above, the second particulate PTC may be formed as secondary particles. In this case, if (e.g., when) the battery is charged and discharged, microcracks may be formed in the secondary particles, and the side reaction between the electrolyte (see Figure 1 300) and the positive electrode active material CAM may be accelerated, which may cause gas to appear in the battery. Therefore, the stability and life of the rechargeable battery may be reduced.

[0080] According to one or more embodiments of the present disclosure, the first particulate PTC1 may include yttrium (Y) on its surface. In the present disclosure, the position of the transition metal in the positive electrode active material may be doped with yttrium (Y), and yttrium (Y) may be used as a pillar to inhibit or reduce the cation mixing phenomenon occurring between Li + and Ni 2+ which may lead to an increase in the life of the rechargeable battery.

[0081] In one or more embodiments, the surface of the first particulate PTC1 may be doped with yttrium (Y) having a large ionic radius, so that the resistance of the electrode may be reduced to increase the power of the rechargeable battery.

[0082] Moreover, according to one or more embodiments of the present disclosure, the first particulate PTC1 may include zirconium (Zr) on its surface. Accordingly, the first particulate PTC1 may increase the ionic conductivity on its surface. In the present disclosure, even when (e.g., when) the first particulate PTC1 is formed as a single particle due to firing at a low temperature, the zirconium-containing surface may lead to an improvement in the durability and capacity retention properties of the rechargeable battery. For example, since the first particulate PTC1 includes zirconium (Zr) on its surface, this surface may prevent or reduce the side reaction between the first particulate PTC1 and the electrolyte 300. In this sense, the present disclosure may prevent or reduce the deterioration of the first particulate PTC1 caused by the electrolyte 300. In addition, in the present disclosure, zirconium (Zr) may allow the first particulate PTC1 to have grains with a relatively large particle size (e.g., average particle diameter). Accordingly, the first particulate PTC1 may have high durability and may prevent or reduce microcracks therein.

[0083] The agglomerate ZAG can be provided in the space between the first particle PTC1 and the second particle PTC2. The agglomerate ZAG can be derived from a flux that will be discussed in more detail. The agglomerate ZAG can include at least one selected from cobalt (Co), aluminum (Al), yttrium (Y), and zirconium (Zr). For example, the agglomerate ZAG can be a cluster formed by the agglomeration of a part of the flux that is not coated on the surfaces of the first particle PTC1 and the second particle PTC2. Figure 2 The agglomerate ZAG is depicted, however, in the present disclosure, the agglomerate ZAG does not have to be present.

[0084] Figure 3 A flowchart illustrating a method of manufacturing a positive electrode active material according to one or more embodiments of the present disclosure is shown. Figures 4 to 6 A simplified diagram illustrating Figure 3 a method of manufacturing a positive electrode active material is shown.

[0085] Referring to Figure 3 and Figure 4 , the first particle PTC1 (S100) can be synthesized.

[0086] The method of synthesizing the first particle PTC1 will be described in more detail below. First, a first precursor PRE1 can be prepared. The first precursor PRE1 can include nickel (Ni) and the symbol Ma of Chemical Formula 1 discussed above. The symbol Ma can include at least one element selected from Co, Al, Mn, Na, Mg, Ca, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, and Sn. For example, the symbol Ma can include Co and Mn.

[0087] In one or more embodiments, the first precursor PRE1 can be obtained by a co-precipitation method. For example, the co-precipitation method can include dissolving raw materials of transition metals in a solvent (such as distilled water) to obtain a transition metal salt solution, and continuously supplying the transition metal salt solution, a chelating agent, and an alkaline aqueous solution to a reactor. The precipitate can be collected in a slurry (for example, collected in the form of a slurry), and then the slurry solution can be filtered and dried to obtain a transition metal composite oxide, that is, the first precursor PRE1.

[0088] In the present disclosure, the raw material of the transition metal may include a metal salt of at least one element selected from Ni, Co, Al, Mn, Na, Mg, Ca, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, and Sn. The metal salt may include a sulfate, a nitrate, an acetate, a halide, or a hydroxide, and there is no particular limitation as long as the material can be dissolved in a solvent. The raw material of the transition metal according to one or more embodiments may include one or more of a nickel salt, a cobalt salt, and an aluminum salt. The raw materials of the transition metal may be mixed by adjusting the molar ratio to allow the positive electrode active material to have high capacity retention properties. For example, the molar ratio may determine the subscript "x1" of Chemical Formula 1.

[0089] The first precursor PRE1, the lithium raw material, and the flux may be mixed in a certain ratio to form a mixture. For example, the first precursor PRE1, the lithium raw material, and the flux may be mixed in a molar ratio of about 1.06:1:0.02. The lithium raw material may be used without particular limitation as long as it is used to manufacture the positive electrode active material. For example, the lithium raw material may include a lithium salt (such as lithium carbonate, lithium nitrate, lithium hydroxide, or lithium sulfate).

[0090] When the flux is added and mixed, the flux and the lithium raw material may react to form a liquid intermediate. In this case, when the intermediate reacts with the first precursor PRE1, rearrangement may occur to reduce the surface tension. After rearrangement, solution reprecipitation may occur to reduce the pores within the lithium composite oxide particles. For example, the reprecipitated lithium composite oxide particles may undergo densification to have the shape of a single particle. The flux may cause the easy formation of single particles, so that the doping material may be formed on the surface of the single particle.

[0091] The flux may include yttrium (Y) and zirconium (Zr). For example, the flux may be Zr (1-x) Y x O 2-x / 2 (0.01 ≤ x ≤ 0.30). The composition ratio (Y / Zr) of yttrium (Y) to zirconium (Zr) in the flux may range from about 0.5 to about 20.

[0092] In the present disclosure, the use of the flux may dope Zr and Y onto the surface of the first particle PTC1 in a firing process that will be discussed in more detail. In one or more embodiments of the present disclosure, yttria-stabilized zirconia (YSZ) may be used as the flux. In the present disclosure, yttria-stabilized zirconia (YSZ) may be added during firing, so that the added yttria-stabilized zirconia (YSZ) may be used as a grain growth promoter to achieve single crystallization. For example, in the present disclosure, yttria-stabilized zirconia (YSZ) may act as an agglomeration inhibitor to obtain an increase in yield caused by a decrease in the firing temperature.

[0093] The mixture can be added to the furnace FRC, and a first firing process STR1 can be carried out at a first temperature. The range of the first temperature can be from about 600 °C to about 1,000 °C. For example, the range of the first temperature can be from about 650 °C to about 900 °C. The first firing process STR1 can be carried out in an oxidizing atmosphere (such as air or oxygen). In the first firing process STR1, the heat treatment time can range from about 10 hours to about 30 hours. In one or more embodiments of the present disclosure, before the first firing process STR1, a preliminary firing process can be additionally carried out at a temperature from about 150 °C to about 800 °C.

[0094] In the first firing process STR1, the first particles PTC1 can be formed from a mixture including a first precursor PRE1, a lithium raw material, and a flux. In one or more embodiments of the present disclosure, the synthesized first particles PTC1 can be subjected to a grinding process. The ground first particles PTC1 can have Figure 2 the first average particle diameter APD1 discussed in. The range of the average particle diameter of the first particles PTC1 can be from about 1 μm to about 5 μm.

[0095] Reference Figure 3 and Figure 5 , the second particles PTC2 (S200) can be synthesized. The method for synthesizing the second particles PTC2 will be described in more detail below. In one or more embodiments, the second precursor PRE2 can be obtained by a method that is substantially the same as or similar to the method of the first precursor PRE1. However, the second precursor PRE2 can be formed to have an average particle diameter greater than that of the first precursor PRE1.

[0096] First, the second precursor PRE2 can be prepared. The second precursor PRE2 can include nickel (Ni) of Chemical Formula 2 discussed above and the symbol Mb. The symbol Mb can include at least one element selected from Co, Al, Mn, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Zr, and Sn. For example, the symbol Mb can include Co and Mn.

[0097] In one or more embodiments, the second precursor PRE2 can be obtained by a co-precipitation method. For example, the co-precipitation method can include dissolving raw materials of transition metals in a solvent (such as distilled water) to obtain a transition metal salt solution, and continuously supplying the transition metal salt solution, a chelating agent, and an alkaline aqueous solution to a reactor. The precipitate can be collected in a slurry (for example, collected in the form of a slurry), and then the slurry solution can be filtered and dried to obtain a transition metal composite oxide, that is, the second precursor PRE2.

[0098] In the present disclosure, the raw material of the transition metal may include a metal salt of at least one element selected from Ni, Co, Al, Mn, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Zr, and Sn. The metal salt may include a sulfate, a nitrate, an acetate, a halide, or a hydroxide, and there is no particular limitation as long as the material can be dissolved in a solvent. The raw material of the transition metal according to one or more embodiments may include one or more of a nickel salt, a cobalt salt, and an aluminum salt. The raw materials of the transition metal may be mixed by adjusting the molar ratio to allow the positive electrode active material to have a high capacity retention property. For example, the molar ratio may determine the subscript "x2" of Chemical Formula 2.

[0099] The second precursor PRE2 and the lithium raw material may be mixed in a certain ratio to form a mixture. For example, the second precursor PRE2 and the lithium raw material may be mixed at a molar ratio of about 1:1. The lithium raw material may be used without particular limitation as long as it is used to manufacture the positive electrode active material. For example, the lithium raw material may include a lithium salt (such as lithium carbonate, lithium nitrate, lithium hydroxide, or lithium sulfate).

[0100] The mixture may be added to the furnace FRC, and a second firing process STR2 may be performed at a second temperature. The range of the second temperature may be from about 700 °C to about 1,000 °C. For example, the range of the second temperature may be from about 700 °C to about 800 °C. The second temperature may be less than the first temperature. In the second firing process STR2, the heat treatment time may range from about 10 hours to about 30 hours.

[0101] In the second firing process STR2, the second particles PTC2 may be formed from a mixture including the second precursor PRE2 and the lithium raw material. In one or more embodiments of the present disclosure, the synthesized second particles PTC2 may be subjected to a grinding process. The ground second particles PTC2 may have Figure 2 the second average particle diameter APD2 discussed in. The second particles PTC2 may have an average particle diameter of about 10 μm to about 25 μm.

[0102] The detailed description of the second firing process STR2 may be the same as or similar to the detailed description of the first firing process STR1.

[0103] Reference Figure 3 and Figure 6, the first particles PTC1 and the second particles PTC2 can be mixed with each other (S300). In one or more embodiments, the first particles PTC1 and the second particles PTC2 can be mixed in a weight ratio of about 95:5 to about 50:50. In one or more embodiments, the first particles PTC1 and the second particles PTC2 can be mixed in a weight ratio of about 5:95 to about 50:50. When the first particles PTC1 are mixed with the second particles PTC2 (having an average particle size different from the average particle size of the first particles PTC1), a positive electrode active material having a bimodal type or variety can be prepared. The mixed first particles PTC1 and second particles PTC2 can be cleaned and dried.

[0104] In addition, the first particles PTC1 and the second particles PTC2 can be further subjected to a coating process. The coating process can include coating the surfaces of the first particles PTC1 and the second particles PTC2 with at least one selected from cobalt and aluminum.

[0105] For example, the first particles PTC1 and the second particles PTC2 can be mixed with a coating raw material CTS. The coating raw material CTS can be a cobalt compound, an aluminum compound, and / or a mixture thereof (e.g., a suitable mixture). For example, the cobalt compound can include cobalt sulfate, but the present disclosure is not limited thereto.

[0106] The first particles PTC1 and the second particles PTC2 and the coating raw material CTS can be added to a solvent (e.g., distilled water) and mixed. The first particles PTC1, the second particles PTC2, and the coating raw material CTS can be uniformly (e.g., substantially uniformly) mixed in a stirrer MXU. Thereafter, the first particles PTC1 and the second particles PTC2 can be filtered and dried, and then the first particles PTC1 and the second particles PTC2 can be surface-treated. The surface treatment can include performing a heat treatment process in an oxidizing atmosphere (such as air or oxygen). The surface treatment can be performed at a temperature of about 500°C to about 800°C.

[0107] In one or more embodiments of the present disclosure, the coating process can include a dry coating process. For example, a mixture of the first particles PTC1, the second particles PTC2, and the coating raw material CTS (e.g., cobalt hydroxide) can be added and stirred in a dry coating device without a solvent. The obtained dry mixture can be surface-treated.

[0108] The third firing process can be performed by adding a mixture of the first particles PTC1, the second particles PTC2, and the coating raw material CTS and performing a heat treatment at a third temperature. The range of the third temperature can be about 700°C to about 1,000°C. For example, the range of the third temperature can be about 650°C to about 900°C, such as about 650°C to about 750°C.

[0109] Therefore, a reference can be manufactured according to one or more embodiments of the present disclosure. Figure 2 The positive electrode active material CAM discussed above.

[0110] In addition to the use of the positive electrode active material CAM according to one or more embodiments of the present disclosure, Figure 1 the positive electrode 100 can be manufactured by a common method for manufacturing a positive electrode. For example, the positive electrode active material CAM, binder, and conductive material of the present disclosure can be dissolved or dispersed in a solvent to form a mixture. The binder and conductive material can be the same as those discussed above in Figure 1 the positive electrode active material layer AML1. The mixture can be coated on the first current collector COL1 and then dried and pressed to manufacture the positive electrode 100.

[0111] The solvent can be a material used in the art. For example, the solvent can include at least one selected from dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, water, and combinations thereof (e.g., any suitable combination).

[0112] In one or more embodiments, the mixture can be cast on a specific support to manufacture a film or the positive electrode active material layer AML1. The positive electrode 100 can be manufactured by laminating the positive electrode active material layer AML1 on the first current collector COL1.

[0113] Figure 7 FIG. shows a simplified cross-sectional view of a rechargeable lithium battery according to one or more embodiments of the present disclosure. Referring to Figure 7 , the rechargeable lithium battery can include a positive electrode 100, a negative electrode 200, and a separator 400. The descriptions of the positive electrode 100, negative electrode 200, and separator 400 can be substantially the same as those discussed above in Figure 1 the rechargeable lithium battery.

[0114] Figure 7 The positive electrode 100, negative electrode 200, and separator 400 of can be wound or folded to form an electrode assembly. The electrode assembly can be housed in a battery case 500. The electrode assembly can include a plurality of electrode assemblies. The separator 400 can be provided in the electrode assembly. The electrode assemblies can be provided in the battery case 500 in a stacked manner. The battery case 500 can be filled with an electrolyte (see Figure 1 300). The battery case 500 can be sealed by a cap assembly 600. The battery case 500 according to one or more embodiments of the present disclosure can have a cylindrical shape, a prismatic shape, or a pouch shape. The rechargeable lithium battery according to one or more embodiments of the present disclosure can be used in devices such as laptop computers, smartphones, or electric vehicles.

[0115] In this document, the present disclosure will be described in more detail with reference to one or more embodiments. The following embodiments are provided for illustrative purposes only and should not be construed as limiting the scope of the present disclosure.

[0116] Embodiment 1: Manufacture of the positive electrode active material

[0117] Preparation 1: Manufacture of the small particle precursor

[0118] The co-precipitation method is used to manufacture the small particle precursor. The following steps are adopted to manufacture nickel-based metal hydroxide (Ni 0.94 Co 0.05 Mn 0.01 (OH) 2 ) as the small particle precursor.

[0119] Nickel sulfate (Ni 2 SO 4 ·6H 2 O), cobalt sulfate (CoSO 4 ·7H 2 O), and manganese sulfate (MnSO 4 ·H 2 O) with a molar ratio of approximately 90:7:3 as the raw materials for the nickel-based metal hydroxide are dissolved in distilled water as the solvent to prepare a mixed solution of metal raw materials. The mixed solution of metal raw materials, ammonia water, and sodium hydroxide are added and reacted in a reactor.

[0120] The slurry solution in the reactor is filtered and rinsed with high-purity distilled water. The rinsed material is dried in a hot air oven at approximately 210 °C for 24 hours to obtain a small particle precursor (Ni 0.90 Co 0.07 Mn 0.03 (OH) 2 ) powder with a particle size (e.g., average particle diameter) of approximately 3 μm.

[0121] Preparation 2: Manufacture of the small particle lithium composite oxide

[0122] The small particle precursor of Preparation 1, anhydrous lithium hydroxide (LiOH), and a flux (YSZ) are dry-mixed using a Henschel mixer to obtain a mixture. Lithium, transition metals, and the flux are mixed in a molar ratio of approximately 1.06:1:0.02. The transition metals refer to the total of the transition metals contained in the small particle precursor (Ni + Co + Mn). The composition ratio of yttrium to zirconium (Y / Zr) of the flux is approximately 8.695.

[0123] Heat the mixture in an oxygen atmosphere at about 800 °C (or the first firing process) for about 15 hours to synthesize a first lithium composite oxide as the first particles. Grind the first particles with a jet mill under a pressure of about 3 bar.

[0124] Preparation 3: Manufacture of large-particle precursors

[0125] Use the coprecipitation method to manufacture large-particle precursors. Employ the steps described subsequently to manufacture nickel-based metal hydroxides (Ni 0.94 Co 0.05 Al 0.01 (OH) 2 ) as large-particle precursors.

[0126] Dissolve nickel sulfate (Ni 2 SO 4 ·6H 2 O), cobalt sulfate (CoSO 4 ·7H 2 O), and aluminum sulfate (Al 2 (SO 4 ) 3 ·H 2 O) having a molar ratio of about 90:7:3 as raw materials of nickel-based metal hydroxides in distilled water as a solvent to prepare a mixed solution of metal raw materials. Prepare a dilute solution of ammonia water (NH 4 OH) and sodium hydroxide (NaOH) as a precipitant to form a complex. Thereafter, add the mixed solution of metal raw materials, the dilute ammonia water solution, and sodium hydroxide to the reactor. Add sodium hydroxide to the reactor to maintain the pH of the mixture in the reactor. While stirring the mixture in the reactor, the reaction proceeds for about 20 hours.

[0127] Filter the slurry solution in the reactor and rinse it with high-purity distilled water. Dry the rinsed material in a hot air oven at 190 °C for 24 hours to obtain a powder of large-particle precursors (Ni 0.90 Co 0.07 Al 0.03 (OH) 2 ) having a particle size (e.g., average particle diameter) of about 18 μm.

[0128] Preparation 4: Manufacture of large-particle lithium composite oxides

[0129] The large particle precursor of Preparation 3 and anhydrous lithium hydroxide (LiOH) were dry mixed using a Henschel mixer to obtain a mixture. Lithium and transition metals were mixed at a molar ratio of approximately 1:1. The transition metals refer to the total sum of transition metals contained in the large particle precursor (Ni + Co + Al). The mixture was heated in an oxygen atmosphere at approximately 750 °C (or the second firing process) for approximately 15 hours to synthesize a second lithium composite oxide as the second particle. The second particle was ground using a jet mill under a pressure of approximately 3 bar.

[0130] Preparation 5: Manufacture of bimodal particles

[0131] The second particles (Preparation 4) with an average particle size of approximately 18 μm and the first particles (Preparation 2) with an average particle size of approximately 3 μm were mixed at a weight ratio of approximately 70:30 to prepare bimodal particles. The bimodal particles were added and rinsed with distilled water. Approximately 20 mol% cobalt sulfate was added to sodium hydroxide to prepare cobalt hydroxide for cobalt coating.

[0132] After the filtration and drying process, a mixture of the first particles PTC1 and the second particles PTC2 (in which approximately 5 mol% lithium hydroxide and approximately 0.05 mol% zirconium dioxide (ZrO 2 )) was heat treated (or surface treated) in an oxygen atmosphere at approximately 700 °C for approximately 15 hours to complete the cobalt coating. Thus, the positive electrode active material according to the present embodiment was obtained.

[0133] Preparation 6: Manufacture of rechargeable lithium batteries

[0134] Approximately 96 g of the positive electrode active material of Preparation 5, approximately 2 g of polyvinylidene fluoride, approximately 47 g of N-methylpyrrolidone as a solvent, and approximately 2 g of carbon black as a conductive material were mixed to manufacture a positive electrode active material slurry.

[0135] The positive electrode active material slurry was coated on an aluminum film using a doctor blade to form a thin electrode plate. The electrode plate was dried at approximately 135 °C for approximately 3 hours or longer, and then pressed and vacuum dried to form a positive electrode.

[0136] A 2032-type or kind coin cell was manufactured using the positive electrode and a lithium metal counter electrode. A separator formed of a porous polyethylene (PE) film (with a thickness of approximately 16 μm) was inserted between the positive electrode and the lithium metal counter electrode. An electrolyte was introduced to manufacture a 2032-type or kind coin cell. The electrolyte was a solution in which approximately 1.1 M LiPF 6 was dissolved in a solvent (in which ethylene carbonate (EC) and ethyl methyl carbonate (EMC) were mixed at a volume ratio of 3:5).

[0137] Comparative Example 1

[0138] A rechargeable lithium battery is manufactured by substantially the same method as in Embodiment 1, except that a flux (YSZ) is added and mixed in Preparation 4, and zirconia (ZrO 2 ) is not added in Preparation 5.

[0139] Comparative Example 2

[0140] A rechargeable lithium battery is manufactured by substantially the same method as in Embodiment 1, except that a flux (YSZ) is not used in Preparation 2.

[0141] Comparative Example 3

[0142] A rechargeable lithium battery is manufactured by substantially the same method as in Embodiment 1, except that zirconia (ZrO 2 ) is not added in Preparation 5.

[0143] Experimental Example 1: Elemental Analysis (SEM-EDS) of Positive Electrode Active Material

[0144] The positive electrode active material manufactured in Embodiment 1 is captured by a scanning transmission electron microscope (STEM) for energy-dispersive X-ray spectroscopy (EDS). Thus, the elements on the surface of the first particles (small particles) are analyzed, and the elements on the surface of the second particles (large particles) are analyzed.

[0145] Figure 8A An SEM image of the surface of the first particle PTC1 of the positive electrode active material manufactured in Embodiment 1 is depicted. Figure 8B The EDS results of the measured components of the first particle PTC1 are depicted.

[0146] Figure 9A An SEM image of the surface of the second particle PTC2 of the positive electrode active material manufactured in Embodiment 1 is depicted. Figure 9B The EDS results of the measured components of the second particle PTC2 are depicted.

[0147] Reference Figure 8A and Figure 8B , it is determined that zirconium (Zr) and yttrium (Y) are doped uniformly (e.g., substantially uniformly) on the surface of the first particle PTC1 or the small particles.

[0148] The term "surface" used in this description may refer to the outermost layer of the particles. Reference Figure 8A and Figure 8B , it is determined that zirconium (Zr) and yttrium (Y) are doped uniformly (e.g., substantially uniformly) on the outermost layer of the first particle PTC1.

[0149] Reference Figure 9A and Figure 9B, it is determined that the composition of yttrium (Y) is almost absent in the second particles PTC2 or the large particles.

[0150] In this sense, it is determined that yttrium (Y) is doped uniformly (e.g., substantially uniformly) on the surface of the small particles, and a very small amount of yttrium (Y) is doped on the surface of the large particles.

[0151] Experimental Example 2: Life of rechargeable lithium battery

[0152] A charge / discharge test system (manufacturer: TOYO, model: TOYO-3100) was used to evaluate the capacity retention properties of each of the coin cell monomers of Embodiment 1 and Comparative Examples 1 to 3.

[0153] Each of the coin cell monomers was charged at a constant current of about 1C at about 45 °C until the voltage reached about 4.3V, and then charged at a constant voltage until the current reached about 0.05C. After pausing for about 10 minutes, the fully charged cell monomer was discharged at a constant current of about 1C until the voltage reached about 3V, and this cycle was repeated 150 times.

[0154] Table 1 lists the capacities and retention performances of the coin cell monomers of the embodiment and the coin cell monomers of the comparative examples. After the initial charge and discharge of each of the coin cell monomers, the coin cell monomers were repeatedly charged and discharged at about 1C at about 45 °C 50 times to measure the 50th discharge capacity, and the ratio (%) of the 50th discharge capacity to the initial discharge capacity is represented as the "high-temperature life" listed in Table 1. For example, the "high-temperature life" refers to the capacity retention rate.

[0155] [Table 1]

[0156]

[0157] Referring to Table 1, it is determined that the coin cell monomers of the embodiment have improved capacity retention properties compared to the coin cell monomers of the comparative examples. The composition of yttrium (Y) present on the surface of the small particles is much larger than the composition of yttrium (Y) present on the surface of the large particles, and thus it is determined that the capacity retention properties of the rechargeable lithium battery are improved.

[0158] To overcome the difference in conductivity between the polycrystalline large particles and the single-crystalline small particles, the present disclosure may propose applying only a flux (such as YSZ) to the small particles to increase the conductivity of the single-crystalline small particles, and as a result, the conductivity balance between the large particles and the small particles can be achieved, thereby improving the capacity retention properties of the rechargeable lithium battery.

[0159] In the positive electrode active material for a rechargeable lithium battery according to the present disclosure, the first particles or small particles may include yttrium (Y) and zirconium (Zr). The first particles or small particles may have a higher composition of yttrium (Y) than the composition of the second particles or large particles. Accordingly, the positive electrode active material of the present disclosure may have high ionic conductivity. The power and capacity retention properties of a rechargeable lithium battery including the positive electrode active material of the present disclosure may be improved.

[0160] According to embodiments of the present invention described herein, the battery management system (BMS) device and / or any other related devices or components may be implemented using any suitable hardware, firmware (e.g., application specific integrated circuit), software, or a combination of software, firmware, and hardware. For example, the various components of the device may be formed on one integrated circuit (IC) chip or separate IC chips. Further, the various components of the device may be implemented on a flexible printed circuit film, tape carrier package (TCP), or printed circuit board (PCB), or formed on a single substrate. Further, the various components of the device may be processes or threads running on one or more processors in one or more computing devices, which execute computer program instructions and interact with other system components to perform the various functions described herein. The computer program instructions are stored in a memory, which may be implemented in a computing device using standard memory devices, such as, for example, random access memory (RAM). The computer program instructions may also be stored in other non-transitory computer-readable media, such as, for example, CD-ROM, flash drive, etc. And, those skilled in the art will recognize that, without departing from the scope of the present disclosure, the functions of various computing devices may be combined or integrated into a single computing device, or the functions of a particular computing device may be distributed over one or more other computing devices.

[0161] In the present disclosure, "not including one or any 'component'", "excluding one or any 'component'", "free of 'component'", etc. mean that the 'component' is not added, selected, or used as a component in the composition / structure, but may still include less than an appropriate amount of the 'component' due to other impurities and / or external factors.

[0162] Although one or more embodiments of the present disclosure have been described with reference to the accompanying drawings, it will be understood that one or more suitable changes in form and detail may be made thereto without departing from the spirit and scope of the present disclosure. Therefore, it will be understood that the above one or more embodiments are illustrative and not restrictive in all respects.

Claims

1. A positive electrode active material comprising: first particles including a first lithium composite oxide and having a first average particle size; and second particles including a second lithium composite oxide and having a second average particle size greater than the first average particle size, wherein the first particle comprises yttrium and zirconium on a surface of the first particle, wherein the second particle does not have yttrium on a surface of the second particle, or the second particle includes yttrium on a surface of the second particle, wherein the yttrium on the surface of the first particle has a first composition, wherein the yttrium on the surface of the second particle has a second composition, and The ratio of the first composition to the second composition is greater than 100.

2. The positive electrode active material according to claim 1, wherein the first lithium composite oxide is represented by Chemical Formula 1, Chemical formula 1 Li a1 Ni x1 Ma 1-x1 Zr w1 Y c1 O b1 in, In Chemical Formula 1, a1 is 0.5 to 1.5, x1 is 0.6 to 0.99, b1 is 1.8 to 2.2, 1-x1 is 0.01 to 0.4, w1 is 0.0005~0.003, c1 is 0.00002 to 0.0003, and Ma includes at least one element selected from Co, Al, Mn, Na, Mg, Ca, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si and Sn. 3 . The positive electrode active material according to claim 1 , wherein the composition ratio of yttrium to zirconium in the first particles is 0.5 to 20. The positive electrode active material according to claim 1 , wherein the first particle is a single crystal. 5 . The positive electrode active material according to claim 1 , wherein the first average particle size is 1 μm to 5 μm.

6. The positive electrode active material according to claim 1, wherein the second lithium composite oxide is represented by Chemical Formula 2, Chemical formula 2 Yes a2 In x2 Yes 1-x2 SHE b2 Wherein in Chemical Formula 2, a2 is 0.5 to 1.5, x2 is 0.6~0.99, b2 is 1.8 to 2.2, 1-x2 is 0.01 to 0.4, and Mb includes at least one element selected from Co, Al, Mn, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Zr and Sn. 7 . The positive electrode active material of claim 1 , wherein the second particle has no yttrium on a surface of the second particle. 8 . The positive electrode active material of claim 1 , wherein the second particle is a secondary particle including a plurality of primary particles.

9. The positive electrode active material of claim 1, wherein the second particles are polycrystalline. 10 . The positive electrode active material according to claim 1 , wherein the second average particle size is 10 μm to 25 μm. 11 . The positive electrode active material of claim 1 , wherein the second particles and the first particles have a weight ratio of 95:5 to 50:

50.

12. A method for producing a positive electrode active material, the method comprising: synthesizing first particles, the first particles including a first lithium composite oxide and having a first average particle size; synthesizing second particles, the second particles including a second lithium composite oxide and having a second average particle size greater than the first average particle size; as well as mixing the first particles and the second particles with each other, wherein the synthesis of the first particle comprises: preparing a precursor of the first particle; as well as The precursor is fired together with a flux, and The flux comprises yttrium and zirconium.

13. The method according to claim 12, wherein the composition ratio Y / Zr of yttrium to zirconium in the flux is 0.5 to 20. 14 . The method of claim 12 , wherein the synthesizing of the first particles is performed at 650° C. to 900° C. for 10 hours to 30 hours.

15. The method of claim 12, wherein The first average particle size is 1 μm to 5 μm, and The second average particle size is 10 μm to 25 μm.

16. The method according to claim 12, wherein the first lithium composite oxide is represented by Chemical Formula 1, Chemical formula 1 Li a1 Ni x1 Ma 1-x1 Zr w1 Y c1 O b1 Wherein in Chemical Formula 1, a1 is 0.5 to 1.5, x1 is 0.6 to 0.99, b1 is 1.8 to 2.2, 1-x1 is 0.01 to 0.4, w1 is 0.0005~0.003, c1 is 0.00002 to 0.0003, and Ma includes at least one element selected from Co, Al, Mn, Na, Mg, Ca, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si and Sn.

17. The method according to claim 12, wherein the second lithium composite oxide is represented by Chemical Formula 2, Chemical formula 2 Yes a2 In x2 Yes 1-x2 SHE b2 in, In chemical formula 2, a2 is 0.5 to 1.5, x2 is 0.6~0.99, b2 is 1.8 to 2.2, 1-x2 is 0.01 to 0.4, and Mb includes at least one element selected from Co, Al, Mn, Na, Mg, Ca, Y, Ti, Hf, V, Nb, Ta, Cr, Mo, W, Fe, Cu, Ag, Zn, B, Ga, C, Si, Zr and Sn. 18 . The method of claim 12 , wherein the mixing of the first particles and the second particles with each other comprises mixing the second particles and the first particles in a weight ratio of 95:5 to 50:

50.

19. A positive electrode for a rechargeable lithium battery, the positive electrode comprising the positive electrode active material according to any one of claims 1 to 11 or the positive electrode active material prepared by the method according to any one of claims 12 to 18.

20. A rechargeable lithium battery comprising the positive electrode as claimed in claim 19.

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