Cathode active material, fabrication method of the same, and lithium secondary battery including the same

Abstract

A method for manufacturing a positive electrode active material according to the present invention may include the steps of: preparing a precursor comprising a transition metal hydroxide; mixing the precursor with a lithium source to produce a mixture; melting the lithium source in the mixture to produce a base positive electrode active material; performing a first heat treatment on the base positive electrode active material to produce a first preliminary positive electrode active material; cooling the first preliminary positive electrode active material to produce a second preliminary positive electrode active material; and performing a second heat treatment on the cooled second preliminary positive electrode active material to produce a positive electrode active material.

Description

Technology Field

[0001] The present invention relates to a positive electrode active material, a method for manufacturing the same, and a lithium secondary battery comprising the same. More specifically, the invention relates to a positive electrode active material comprising at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al) and a doping element, a method for manufacturing the same, and a lithium secondary battery comprising the same. Background Technology

[0002] A positive electrode active material refers to an active material present within the positive electrode of a secondary battery that electrochemically stores and converts electrical energy.

[0003] The cathode active material present within the cathode holds lithium ions in its initial state and plays the role of supplying lithium ions to the anode during the charging process of the secondary battery.

[0004] Accordingly, cathode active materials are utilized in various industries, including lithium-ion batteries, lithium-metal batteries, lithium-air batteries, lithium-ion polymer batteries, and all-solid-state batteries.

[0005] As the fields of application increase, various cathode active materials are being researched. For example, Korean Patent Publication No. 10-0815583 discloses a method for manufacturing a cathode active material for a lithium secondary battery, comprising the steps of: preparing a co-precipitation compound by mixing a metal salt aqueous solution containing a first metal including nickel, cobalt and manganese, and optionally a second metal, a chelating agent, and a basic aqueous solution; preparing an active material precursor by drying or heat-treating the co-precipitation compound; and preparing a lithium composite metal oxide by mixing the active material precursor with a lithium salt and calcining the mixture, wherein the lithium composite metal oxide has a layered structure. The problem to be solved

[0006] The technical problem that the present invention aims to solve is to provide a positive electrode active material that improves the capacity retention rate of a lithium secondary battery.

[0007] Another technical problem that the present invention aims to solve is to provide a cathode active material that improves the initial capacity of a lithium secondary battery.

[0008] Another technical problem that the present invention aims to solve is to provide a method for manufacturing a cathode active material with reduced manufacturing process costs.

[0009] Another technical problem that the present invention aims to solve is to provide a method for manufacturing a cathode active material with reduced manufacturing time.

[0010] Another technical problem that the present invention aims to solve is to provide a method for manufacturing a cathode active material that is easy to mass-produce.

[0011] The technical problems that the present invention aims to solve are not limited to those described above. means of solving the problem

[0012] To solve the above technical problem, a positive electrode active material is provided.

[0013] According to one embodiment, the cathode active material comprises at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), and the region within 40% of the radius of the cathode active material starting from the center of the cathode active material is defined as the center, and the size heterogeneity index, which is an indicator that quantitatively represents the size deviation of the primary particles of the cathode active material in the center, may be 0.26 or higher and 0.43 or lower.

[0014] According to one embodiment, the cathode active material further comprises a doping element, and the doping element may include any one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W).

[0015] According to one embodiment, the surface portion is defined as an area within 60% of the radius of the cathode active material starting from the surface of the cathode active material, and the size heterogeneity index, which is an indicator that quantitatively represents the size deviation of the primary particles of the cathode active material in the surface portion, may be 0.25 or higher and 0.45 or lower.

[0016] According to one embodiment, the average size of the primary particles of the positive active material on the surface portion is 400 nm or less, the average absolute orientation angle of the primary particles of the positive active material on the surface portion is 17° or less, and the aspect ratio of the primary particles of the positive active material on the surface portion is 6 or less.

[0017] According to one embodiment, the surface may include an Orientation Heterogeneity Index, which is an indicator that quantitatively represents the deviation of the orientation angle of the primary particles of the cathode active material, of 12.5° or less.

[0018] According to one embodiment, the grain boundary length density, which is an indicator that quantitatively indicates how densely grain boundaries are distributed within the particles of the cathode active material on the surface, may be 5.576 or higher.

[0019] To solve the above technical problem, a lithium secondary battery is provided that has the above-described positive active material applied thereto.

[0020] According to one embodiment, the apparatus may include an anode having the anode active material described above, a cathode spaced apart from the anode, and a solid electrolyte or liquid electrolyte provided between the anode and the cathode.

[0021] To solve the above technical problem, the present invention provides a method for manufacturing a positive electrode active material.

[0022] According to one embodiment, the method for manufacturing the cathode active material may include the steps of: preparing a precursor comprising a transition metal hydroxide; mixing the precursor with a lithium source to produce a mixture; melting the lithium source in the mixture to produce a base cathode active material; performing a first heat treatment on the base cathode active material to produce a first preliminary cathode active material; cooling the first preliminary cathode active material to produce a second preliminary cathode active material; and performing a second heat treatment on the cooled second preliminary cathode active material to produce the cathode active material.

[0023] According to one embodiment, the precursor may include having orientation, including at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), and may include a plurality of primary particles having a rod shape arranged in a radiating form on the surface, wherein the average thickness of the primary particles on the surface of the precursor is 100 nm or less, the average length of the primary particles on the surface of the precursor is 2,000 nm or less, the average size of the primary particles on the surface of the precursor is 300 nm or less, the average aspect ratio of the primary particles on the surface of the precursor is 60 or less, and the average absolute orientation angle of the primary particles on the surface of the precursor is 15° or less.

[0024] According to one embodiment, depending on the type of lithium source, the lithium melting temperature for melting the lithium source in the mixture may be controlled.

[0025] According to one embodiment, when the lithium source is lithium hydroxide (LiOH), the lithium melting temperature is controlled to be 450°C or higher and 500°C or lower; when the lithium source is lithium carbonate (Li2CO3), the lithium melting temperature is controlled to be 700°C or higher and 750°C or lower; when the lithium source is lithium nitrate (LiNO3), the lithium melting temperature is controlled to be 250°C or higher and 300°C or lower; and when the lithium source is lithium acetate (LiCH3COO), the lithium melting temperature is controlled to be 250°C or higher and 300°C or lower.

[0026] According to one embodiment, in the step of manufacturing the first pre-positive active material, the first heat treatment temperature of the base positive active material is controlled to be 300°C or higher and 800°C or lower, and in the step of manufacturing the second pre-positive active material, the cooling rate of the first pre-positive active material that has undergone the first heat treatment is controlled to be 0.1°C / min or higher.

[0027] According to one embodiment, in the step of manufacturing the cathode active material, the secondary heat treatment temperature of the second preliminary cathode active material may be controlled to be 600°C or higher and 1,000°C or lower.

[0028] According to one embodiment, among the steps of preparing the precursor, preparing the mixture, or preparing the cathode active material, at least one process may include adding a dopant or not adding a dopant.

[0029] According to one embodiment, the dopant may include any one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W).

[0030] According to one embodiment, the precursor may include at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al).

[0031] According to one embodiment, the lithium melting temperature for manufacturing the base cathode active material by melting lithium in the mixture may be higher than the primary heat treatment temperature depending on the type of lithium source, and the capacity retention rate of the lithium secondary battery to which the cathode active material is applied may be controlled according to the melting time at which the lithium source is melted at the lithium melting temperature.

[0032] According to one embodiment, the lithium source is lithium hydroxide (LiOH), the lithium dissolution temperature is controlled to 450°C, and the capacity retention rate of the lithium secondary battery may be improved as the dissolution time is controlled to 5 hours or more.

[0033] According to one embodiment, the capacity retention rate of the lithium secondary battery to which the first pre-positive active material is applied may be controlled according to the cooling rate at which the first pre-positive active material is cooled.

[0034] According to one embodiment, the cooling rate of the first pre-positive active material may be controlled to be greater than 0.1℃ / min and less than 2.0℃ / min, thereby improving the capacity retention rate of the lithium secondary battery. Effects of the invention

[0035] A method for manufacturing a positive electrode active material according to the present invention may include the steps of: preparing a precursor comprising a transition metal hydroxide; mixing the precursor with a lithium source to produce a mixture; melting the lithium source in the mixture to produce a base positive electrode active material; performing a first heat treatment on the base positive electrode active material to produce a first preliminary positive electrode active material; cooling the first preliminary positive electrode active material to produce a second preliminary positive electrode active material; and performing a second heat treatment on the cooled second preliminary positive electrode active material to produce the positive electrode active material.

[0036] In the step of manufacturing the above base cathode active material, the lithium source is melted in the mixture so that the molten lithium source can be uniformly coated on the surface of the precursor.

[0037] And, after the base cathode active material is heat-treated in the step of manufacturing the first pre-cathode active material, the first pre-cathode active material that has undergone primary heat treatment in the step of manufacturing the second pre-cathode active material may be cooled.

[0038] In addition, a dopant may be added to at least one of the steps of preparing the precursor, preparing the mixture, or preparing the positive electrode active material.

[0039] Accordingly, in the step of manufacturing the above-mentioned cathode active material, if the second pre-cathode active material, which is cooled from the first pre-cathode active material, is subjected to a second heat treatment, the above-mentioned cathode active material can be provided in which lithium elements are uniformly distributed and crystallinity and structural stability are improved.

[0040] The cathode active material manufactured by the above-described manufacturing method may include at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al) and a doping element.

[0041] The size heterogeneity index of the primary particles in the center of the cathode active material may be 0.26 or higher and 0.43 or lower, and the size heterogeneity index of the primary particles on the surface may be 0.25 or higher and 0.45 or lower, or the size heterogeneity index, which is an indicator that quantitatively represents the size difference between the primary particles in the center and the surface of the cathode active material, may be 0.25 or higher and 0.45 or lower. In addition, the Orientation Heterogeneity Index, which is an indicator that quantitatively represents the deviation of the orientation angle of primary particles on the surface of the cathode active material, may be 6.0° or more and 12.5° or less, or 12.5° or less, and the Grain Boundary Length Density, which is an indicator that quantitatively represents how densely grain boundaries are distributed within the particles on the surface of the cathode active material, may be 5.576 or more.

[0042] Accordingly, the crystallinity and structural stability of the above-mentioned cathode active material can be improved. Therefore, when the above-mentioned cathode active material is applied to the above-mentioned lithium secondary battery, the capacity retention rate and initial capacity of the above-mentioned lithium secondary battery can be improved. Brief explanation of the drawing

[0043] FIG. 1 is a flowchart illustrating a method for manufacturing a positive electrode active material according to an embodiment of the present invention. FIG. 2 is a drawing illustrating the step of preparing a precursor according to an embodiment of the present invention. FIG. 3 is a drawing for explaining the steps of preparing a mixture according to an embodiment of the present invention. FIG. 4 is a diagram illustrating the steps for manufacturing a base positive electrode active material according to an embodiment of the present invention. FIG. 5 is a diagram illustrating the step of manufacturing a first preliminary cathode active material according to an embodiment of the present invention. FIG. 6 is a diagram illustrating the step of manufacturing a second preliminary cathode active material according to an embodiment of the present invention. FIG. 7 is a diagram illustrating the steps for manufacturing a positive electrode active material according to an embodiment of the present invention. FIG. 8 is a drawing for explaining a positive electrode active material according to an embodiment of the present invention. FIG. 9 is a diagram illustrating the surface and center of the positive electrode active material according to experimental examples and comparative examples of the present invention. FIG. 10 is a diagram illustrating the Size Heterogeneity Index of the cathode active material according to experimental examples and comparative examples of the present invention. FIG. 11 is a diagram illustrating the Orientation Heterogeneity Index of the cathode active material according to experimental examples and comparative examples of the present invention. FIG. 12 is a graph showing an SEM image of a positive electrode active material according to Comparative Example 1 of the present invention, a particle size deviation between the surface and center of the primary particles, and an orientation angle deviation between the surface of the primary particles. FIG. 13 is a graph showing an SEM image of a positive electrode active material according to Comparative Example 2 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. Figure 14 is a graph showing an SEM image of the cathode active material according to Experimental Example 1 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles. Figure 15 is a graph showing an SEM image of the cathode active material according to Experimental Example 2 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles. Figure 16 is a graph showing an SEM image of the cathode active material according to Experimental Example 3 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles. Figure 17 is a graph showing an SEM image of the cathode active material according to Experimental Example 4 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles. FIG. 18 shows the performance of a half cell with an anode active material applied according to experimental examples and comparative examples of the present invention, and the size heterogeneity index (Size Heterogeneity Index, H) of the primary particles of the anode active material. s ) and Orientation Heterogeneity Index (H θ This is a graph for comparing relationships. FIG. 19 is a graph showing an SEM image of the cathode active material according to Experimental Example 1-1 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles. FIG. 20 is a graph showing SEM images of the cathode active material according to Experimental Example 1-2 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 21 is a graph showing SEM images of the cathode active material according to Experimental Examples 1-3 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 22 is a graph showing SEM images of the cathode active material according to Experimental Examples 1-4 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 23 shows the performance of a half cell with an anode active material applied according to experimental examples and comparative examples of the present invention and the size heterogeneity index (Size Heterogeneity Index, H) of the primary particles of the anode active material. s) and Orientation Heterogeneity Index (H θ This is a graph for comparing relationships. FIG. 24 is a graph showing an SEM image of the cathode active material according to Experimental Example 4-1 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles. FIG. 25 shows the performance of a half cell with an anode active material applied according to experimental examples and comparative examples of the present invention and the size heterogeneity index (Size Heterogeneity Index, H) of the primary particles of the anode active material. s ) and Orientation Heterogeneity Index (H θ This is a graph for comparing relationships. FIG. 26 is a graph showing SEM images of the cathode active material according to Comparative Example 3 and Experimental Example 5 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 27 is a graph showing SEM images of the cathode active material according to Comparative Example 4 and Experimental Example 6 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 28 is a graph showing SEM images of the cathode active material according to Comparative Example 5 and Experimental Example 7 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 29 is a graph showing SEM images of the cathode active material according to Comparative Example 6 and Experimental Example 8 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 30 is a graph showing SEM images of the cathode active material according to Comparative Example 7 and Experimental Example 9 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 31 is a graph showing SEM images of the cathode active material according to Comparative Example 8 and Experimental Example 10 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 32 is a graph showing SEM images of the cathode active material according to Comparative Example 9 and Experimental Example 11 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 33 is a graph showing SEM images of the cathode active material according to Comparative Example 10 and Experimental Example 12 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 34 is a graph showing SEM images of the cathode active material according to Comparative Example 11 and Experimental Example 13 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 35 is a graph showing SEM images of the cathode active material according to Comparative Example 12 and Experimental Example 14 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 36 is a graph showing SEM images of the cathode active material according to Comparative Example 13 and Experimental Example 15 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 37 is a graph showing SEM images of the cathode active material according to Comparative Example 14 and Experimental Example 16 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 38 is a graph showing SEM images of the cathode active material according to Comparative Example 1 and Experimental Examples 2-3 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 39 is a graph showing SEM images of the cathode active material according to Comparative Example 15 and Experimental Example 17 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 40 is a graph showing SEM images of the cathode active material according to Comparative Example 16 and Experimental Example 18 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 41 is a graph showing SEM images of the cathode active material according to Comparative Example 17 and Experimental Example 19 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 42 is a graph showing SEM images of the cathode active material according to Comparative Example 18 and Experimental Example 20 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 43 is a graph showing SEM images of the cathode active material according to Comparative Example 19 and Experimental Example 21 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 44 is a graph showing SEM images of the cathode active material according to Comparative Example 20 and Experimental Example 22 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 45 is a graph showing SEM images of the cathode active material according to Comparative Example 21 and Experimental Example 23 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 46 is a graph showing SEM images of the cathode active material according to Comparative Example 22 and Experimental Example 24 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIG. 47 is a graph showing SEM images of the cathode active material according to Comparative Example 23 and Experimental Example 25 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles. FIGS. 48 to 50 are graphs showing the strength of the positive electrode active material according to comparative examples and experimental examples of the present invention. FIG. 51 is a diagram illustrating the grain boundary length density of the cathode active material according to experimental examples and comparative examples of the present invention. FIGS. 52 to 54 are cross-sectional SEM images for comparing the grain boundary length density of the cathode active material according to comparative examples and experimental examples of the present invention. FIG. 55 is a diagram for explaining the distribution of the area of ​​microcracks (Areal fraction of microcrack) of a positive electrode active material after performing charge / discharge cycles of a secondary battery to which a positive electrode active material according to experimental examples and comparative examples of the present invention is applied. FIGS. 56 to 58 are cross-sectional SEM images for comparing the real fraction of microcrack distribution of a positive electrode active material after performing charge / discharge cycles of a half cell with a positive electrode active material according to experimental examples and comparative examples. FIGS. 59 to 63 are SEM images and graphs for comparing the physical properties of primary particles on the surface of precursors used in the manufacture of cathode active materials according to comparative examples and experimental examples of the present invention. Specific details for implementing the invention

[0044] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. However, the technical concept of the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided to ensure that the disclosed content is thorough and complete and to ensure that the concept of the present invention is sufficiently conveyed to those skilled in the art.

[0045] In this specification, when a component is described as being on another component, it means that it may be formed directly on the other component or that a third component may be interposed between them. Additionally, in the drawings, the thicknesses of the films and regions are exaggerated for the effective description of the technical content.

[0046] Additionally, although terms such as first, second, third, etc., have been used to describe various components in the various embodiments of this specification, these components should not be limited by such terms. These terms are used merely to distinguish one component from another. Accordingly, what is referred to as the first component in one embodiment may be referred to as the second component in another embodiment. Each embodiment described and illustrated herein also includes its complementary embodiment. Furthermore, in this specification, "and / or" is used to mean including at least one of the components listed before and after it.

[0047] In the specification, singular expressions include plural expressions unless the context clearly indicates otherwise. Furthermore, terms such as "include" or "have" are intended to specify the existence of the features, numbers, steps, components, or combinations thereof described in the specification, and should not be understood as excluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof. Additionally, in this specification, "connection" is used to include both indirectly connecting multiple components and directly connecting them.

[0048] Furthermore, in describing the present invention below, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0050] FIG. 1 is a flowchart for explaining a method for manufacturing a positive electrode active material according to an embodiment of the present invention, FIG. 2 is a diagram for explaining a step of preparing a precursor according to an embodiment of the present invention, FIG. 3 is a diagram for explaining a step of manufacturing a mixture according to an embodiment of the present invention, FIG. 4 is a diagram for explaining a step of manufacturing a base positive electrode active material according to an embodiment of the present invention, FIG. 5 is a diagram for explaining a step of manufacturing a first preliminary positive electrode active material according to an embodiment of the present invention, FIG. 6 is a diagram for explaining a step of manufacturing a second preliminary positive electrode active material according to an embodiment of the present invention, FIG. 7 is a diagram for explaining a step of manufacturing a positive electrode active material according to an embodiment of the present invention, and FIG. 8 is a diagram for explaining a positive electrode active material according to an embodiment of the present invention.

[0051] Referring to FIGS. 1 and FIGS. 2, a precursor (110) containing a transition metal hydroxide is prepared (S100).

[0052] The above precursor (110) can be prepared by a co-precipitation reaction using a transition metal source, a chelating agent, and a pH adjuster. In this process, a dopant may be added, or the dopant may not be added. For example, the transition metal source may include at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al). For example, the dopant may include any one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W).

[0053] Accordingly, the precursor (110) may include at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al). Additionally, the precursor (110) may further include a doping element by the dopant, or may not include a doping element. For example, if the precursor (110) includes the doping element, the molar ratio of the doping element may be controlled to be 0.1 mol% or more and 2.0 mol% or less based on the combined molar ratio of the transition metal element of the precursor (110) and the doping element.

[0054] Additionally, the precursor (110) may include a plurality of primary particles having a rod shape arranged on the surface of the precursor (110) in a manner radiating from the center of the precursor (110). For example, the average thickness of the primary particles on the surface of the precursor (110) may be 100 nm or less. For example, the average length of the primary particles on the surface of the precursor (110) may be 2,000 nm or less. For example, the average size of the primary particles on the surface of the precursor (110) may be 300 nm or less. For example, the average aspect ratio of the primary particles on the surface of the precursor (110) may be 60 or less. For example, the average absolute orientation angle of the primary particles on the surface of the precursor (110) may be 15° or less. For example, the average thickness of the primary particles on the surface of the precursor (110) may be 30.5 nm or more and 37.8 nm or less. For example, the average length of the primary particles on the surface of the precursor (110) may be 1,408.2 nm or more and 1,797 nm or less. For example, the average size of the primary particles on the surface of the precursor (110) may be 202.2 nm or more and 257.3 nm or less. For example, the average aspect ratio of the primary particles on the surface of the precursor (110) may be 49.4 or more and 53.5 or less. For example, the average absolute orientation angle of the primary particles on the surface of the precursor (110) may be 3.6° or more and 4.6° or less.

[0055] Accordingly, the orientation of a plurality of primary particles arranged on the surface portion of the precursor (110) can be improved.

[0056] Referring to FIGS. 1 and 3, a mixture (130) is prepared by mixing the precursor (110) and the lithium source (120) (S200).

[0057] The precursor (110) and the lithium source (120) can be physically mixed. For example, the lithium source (120) may be any one of lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium nitrate (LiNO3), or lithium acetate (LiCH3COO).

[0058] In addition, in the step of preparing the mixture (130), the dopant may be added to the precursor (110) and the lithium source (120), or may not be added. In other words, in the step of preparing the mixture (130), the mixture (130) in which the precursor (110), the lithium source (120), and the dopant are physically mixed may be prepared, or the mixture (130) in which the precursor (110) and the lithium source (120) are physically mixed may be prepared. For example, if the mixture (130) contains the doping element by the dopant, the molar ratio of the doping element may be controlled to be 0.1 mol% or more and 2.0 mol% or less based on the combined molar ratio of the transition metal element of the precursor (110) and the doping element. For example, the above dopant may include any one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W).

[0059] Referring to FIGS. 1 and FIGS. 4, the lithium source (120) is melted in the mixture (130) to produce a base positive active material (140) (S300).

[0060] The above mixture (130) can be provided to a heat treatment furnace. Then, after raising the temperature of the heat treatment furnace from room temperature (25°C) to the lithium melting temperature, which is the temperature at which the lithium source (120) melts, the mixture (130) can be heat-treated at the lithium melting temperature, so that the lithium source (120) can melt within the mixture (130). For example, the heating rate can be controlled to be 1.0°C / min or higher.

[0061] In this process, the lithium melting temperature can be controlled differently depending on the type of lithium source (120) in the mixture (130).

[0062] According to one embodiment, when the lithium source (120) is lithium hydroxide (LiOH), the lithium melting temperature can be controlled to be 450°C or higher and 500°C or lower.

[0063] And, if the lithium source (120) is lithium carbonate (Li2CO3), the lithium melting temperature can be controlled to be 700°C or higher and 750°C or lower.

[0064] And, if the lithium source (120) is lithium nitrate (LiNO3), the lithium melting temperature can be controlled to be between 250°C and 300°C.

[0065] And, if the lithium source (120) is lithium acetate (LiCH3COO), the lithium melting temperature can be controlled to be between 250°C and 300°C.

[0066] Accordingly, the lithium source (120) can be melted on the surface of the precursor (110) of the mixture (130). Accordingly, not only is the lithium of the lithium source (120) uniformly distributed on the surface of the precursor (110), but an opportunity is also provided for the lithium of the precursor (110) and the lithium of the lithium source (120) to react before the base positive active material (140) undergoes a first heat treatment. As a result, during the process of the first heat treatment of the base positive active material (140) described later, the reactivity between the precursor (110) of the base positive active material (140) and the lithium of the lithium source (120) in a molten state can be improved.

[0067] And, depending on the melting time during which the lithium source (120) in the mixture (130) melts at the lithium melting temperature, the capacity retention rate and initial capacity of the lithium secondary battery to which the cathode active material described later is applied can be controlled.

[0068] As described above, when the lithium source (120) is lithium hydroxide (LiOH), the lithium melting temperature can be controlled to 450°C.

[0069] According to one embodiment, at the lithium melting temperature, the melting time of the lithium source (120) in the mixture (130) is controlled to be 5 hours or more, so that the lithium source (120) melts and can uniformly cover the surface of the precursor (110). Accordingly, the distribution of lithium elements within the cathode active material described later becomes uniform, and the chemical composition of the cathode active material described later becomes uniform and crystallinity can be improved. Accordingly, the capacity retention rate and initial capacity of the lithium secondary battery to which the cathode active material described later is applied can be improved.

[0070] In contrast, if the melting time of the lithium source (120) in the mixture (130) is controlled to be less than 5 hours at the lithium melting temperature, only a portion of the lithium source (120) is dissolved, and the surface of the precursor (110) cannot be uniformly covered. Accordingly, the distribution of lithium elements in the cathode active material described later becomes non-uniform, and the chemical composition and crystallinity of the cathode active material described later may be reduced. Accordingly, the capacity retention rate and initial capacity of the lithium secondary battery to which the cathode active material described later is applied may be reduced.

[0071] Accordingly, according to an embodiment of the present application, in the step of manufacturing the base positive electrode active material (140), the melting time of the lithium source (120) in the mixture (130) at the lithium melting temperature can be controlled to be 5 hours or more. Accordingly, the lithium source (120) can be melted to uniformly cover the surface of the precursor (110). Accordingly, the distribution of lithium elements within the positive electrode active material described later becomes uniform, and the chemical composition of the positive electrode active material described later becomes uniform and crystallinity can be improved. Accordingly, a positive electrode active material described later that improves the capacity retention rate and initial capacity of a lithium secondary battery can be provided.

[0072] Referring to FIGS. 1 and FIGS. 5, the base positive active material (140) is heat-treated to produce a first preliminary positive active material (151) (S400).

[0073] After raising or lowering the temperature of the heat treatment furnace from the lithium melting temperature to the first heat treatment temperature, the base cathode active material (140) may be heat-treated at the first heat treatment temperature. For example, the rate of raising or lowering the temperature may be controlled to be 0.1℃ / min or higher. For example, the first heat treatment temperature may be controlled to be 300℃ or higher and 800℃ or lower. For example, the first heat treatment time may be controlled to be 1 hour or higher and 24 hours or lower.

[0074] Accordingly, the lithium from the molten lithium source (120) that uniformly covers the surface of the precursor (110) of the base positive electrode active material (140) reacts effectively, and a lithium transition metal oxide with uniformly distributed lithium can begin to form.

[0075] Referring to FIGS. 1 and FIGS. 6, the first preliminary positive active material (151) is cooled to produce a second preliminary positive active material (152) (S500).

[0076] As the temperature of the heat treatment furnace is reduced from the first heat treatment temperature to room temperature (25°C), the first pre-positive active material (151) that has undergone the first heat treatment can be cooled. At this time, depending on the cooling rate (cooling rate) at which the first pre-positive active material (151) is cooled, the capacity retention rate and initial capacity of the lithium secondary battery to which the cathode active material described later is applied can be controlled.

[0077] According to one embodiment, the cooling rate of the first pre-positive active material (151) can be controlled to be greater than 0.1°C / min and less than 2.0°C / min. Accordingly, in the second heat treatment process of the second pre-positive active material (150) described later, not only is abnormal grain growth of the lithium transition metal oxide prevented, but the grains can also grow to have a uniform orientation angle and a uniform size. Accordingly, the crystallinity and structural stability of the cathode active material described later are improved, and the capacity retention rate and initial capacity of the lithium secondary battery to which the cathode active material described later is applied can be improved.

[0078] In contrast, if the cooling rate of the first pre-positive active material (151) is controlled to be 0.1°C / min or less, or 2.0°C / min or more, some lithium transition metal oxide may grow abnormally or defects may be formed in the lithium transition metal oxide during the second heat treatment process of the second pre-positive active material (150) described later. Accordingly, the crystallinity and structural stability of the cathode active material described later are reduced, and the capacity retention rate and initial capacity of the lithium secondary battery to which the cathode active material described later is applied may be reduced.

[0079] Accordingly, according to an embodiment of the present application, in the step of manufacturing the second pre-positive active material (152), the cooling rate of the first pre-positive active material (151) can be controlled to be greater than 0.1°C / min and less than 2.0°C / min. Accordingly, in the secondary heat treatment process of the second pre-positive active material (150) described later, not only is abnormal grain growth of the lithium transition metal oxide prevented, but the grains can also grow to have a uniform orientation angle and a uniform size. Accordingly, the crystallinity and structural stability are improved, and the capacity retention rate and initial capacity of the lithium secondary battery can be improved, and the cathode active material described later can be provided.

[0080] In summary, in the step of manufacturing the base positive active material (140), the lithium source (120) is melted within the mixture (130) so that the molten lithium source (120) can be uniformly coated on the surface of the precursor (110). Then, in the step of manufacturing the second preliminary positive active material (152), the first preliminary positive active material (151), which has undergone a first heat treatment of the base positive active material (140), can be cooled.

[0081] Accordingly, in the step of manufacturing the cathode active material described below, when the second pre-cathode active material (152), which is cooled from the first pre-cathode active material (151), is subjected to a second heat treatment, the cathode active material described below can be provided in which lithium elements are uniformly distributed and crystallinity and structural stability are improved.

[0082] Referring to FIG. 1 and FIG. 7, the cooled second pre-positive active material (152) is subjected to a second heat treatment to produce the above-described positive active material (100) (S600).

[0083] Before raising the temperature of the heat treatment furnace from room temperature (25°C) to the second heat treatment temperature, the dopant may be added and mixed into the second pre-positive active material (152), or the dopant may not be provided. For example, if the second pre-positive active material (152) includes the dopant, the molar ratio of the doping element may be controlled to be 0.1 mol% or more and 2.0 mol% or less, based on the molar ratio of the transition metal element of the second pre-positive active material (152) and the combined molar ratio of the doping element by the dopant. For example, the above dopant may include any one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W).

[0084] Then, after raising the temperature of the heat treatment furnace from room temperature to a second heat treatment temperature, the second pre-positive active material (152) can be heat-treated at the second heat treatment temperature. For example, the heating rate can be controlled to be 1.0℃ / min or higher and 5.0℃ / min or lower. For example, the second heat treatment temperature can be controlled to be 600℃ or higher and 1,000℃ or lower. For example, the second heat treatment time can be controlled to be 5 hours or higher and 15 hours or lower.

[0085] Accordingly, as described above, not only is abnormal grain growth of the lithium transition metal oxide of the second pre-positive active material (152) prevented, but the grains can also grow with a uniform orientation angle and a uniform size. Accordingly, the distribution of lithium elements within the positive active material (100) is uniform, and the crystallinity and structural stability of the positive active material (100) can be improved. Accordingly, when the positive active material (100) is applied to a lithium secondary battery, the capacity retention rate and initial capacity of the lithium secondary battery can be improved.

[0086] In conclusion, the method for manufacturing the positive electrode active material (100) according to an embodiment of the present application may include the steps of: preparing the precursor (110) containing a transition metal hydroxide; mixing the precursor (110) and the lithium source (120) to produce the mixture (130); melting the lithium source (120) in the mixture (130) to produce the base positive electrode active material (140); heat-treating the base positive electrode active material (140) to produce the first preliminary positive electrode active material (151); cooling the first preliminary positive electrode active material (151) to produce the second preliminary positive electrode active material (152); and heat-treating the cooled second preliminary positive electrode active material (152) to produce the positive electrode active material (100).

[0087] In the step of manufacturing the base positive electrode active material (140), the lithium source (120) is melted in the mixture (130) so that the molten lithium source (120) can be uniformly coated on the surface of the precursor (110).

[0088] And, after the base cathode active material (140) is heat-treated in the step of manufacturing the first pre-positive active material (152), the first pre-positive active material (151) that has undergone primary heat treatment may be cooled in the step of manufacturing the second pre-positive active material (152).

[0089] And, the dopant may be added to at least one of the steps of preparing the precursor (110), preparing the mixture (130), or preparing the positive electrode active material (100).

[0090] Accordingly, in the step of manufacturing the above-mentioned positive electrode active material (100), when the second-mentioned positive electrode active material (152), which is cooled from the first-mentioned positive electrode active material (151), is subjected to a second heat treatment, the positive electrode active material (100) can be provided in which lithium elements are uniformly distributed and crystallinity and structural stability are improved.

[0091] Therefore, when the above-mentioned positive electrode active material (100) is applied to a lithium secondary battery, the capacity retention rate and initial capacity of the lithium secondary battery can be improved.

[0092] Referring to FIG. 8, the positive electrode active material (100) manufactured by the above-described manufacturing method is described.

[0093] The above-described positive active material (100) may include at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al) and the doping element. For example, the doping element may be at least one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W). For example, the molar ratio of the doping element may be controlled to be 0.1 mol% or more and 2.0 mol% or less. For example, the molar ratio of nickel may be 40 mol% or more.

[0094] And, as described in detail in FIG. 9, the area within 40% of the radius (R) of the positive active material (100) starting from the center (1) of the positive active material (100) may be defined as the center (2), and the area within 60% of the radius (R) of the positive active material (100) starting from the surface of the positive active material (100) may be defined as the surface portion (3).

[0095] And, as described in detail in FIG. 10, the Size Heterogeneity Index, which is an indicator that quantitatively represents the size difference of primary particles in the center (2) and the surface (3) of the positive active material (100), may be 0.25 or higher and 0.45 or lower, or the Size Heterogeneity Index of primary particles in the center (2) of the positive active material (100) may be 0.26 or higher and 0.43 or lower, and the Size Heterogeneity Index of primary particles in the surface (3) may be 0.25 or higher and 0.45 or lower.

[0096] And, as described in detail in FIG. 11, the Orientation Heterogeneity Index, which is an indicator that quantitatively represents the deviation of the orientation angle of primary particles on the surface portion (3) of the positive electrode active material (100), may be 6.0° or more and 12.5° or less, or 12.5° or less.

[0097] And, as described in detail in FIG. 51, the grain boundary length density, which is an indicator that quantitatively shows how densely grain boundaries are distributed on the surface portion (3) of the positive active material (100), may be 5.576 or higher.

[0098] In addition, the average size of the primary particles on the surface portion (3) of the positive active material (100) may be 400 nm or less, or 124.54 nm or more and 308 nm or less, the average absolute orientation angle of the primary particles on the surface portion (3) of the positive active material (100) may be 17° or less, or 3.6° or more and 15.6° or less, and the aspect ratio of the primary particles on the surface portion (3) of the positive active material (100) may be 6 or less, or 1.41 or more and 3.25 or less.

[0099] Accordingly, the crystallinity and structural stability of the above-mentioned positive electrode active material (100) can be improved. Therefore, when the above-mentioned positive electrode active material (100) is applied to a lithium secondary battery, the capacity retention rate and initial capacity of the lithium secondary battery can be improved.

[0100] In conclusion, the positive active material (100) according to the embodiment of the present application may include at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al) and the doping element.

[0101] In addition, the Size Heterogeneity Index of the primary particles in the center (2) of the cathode active material (100) may be 0.26 or higher and 0.43 or lower, and the Size Heterogeneity Index of the primary particles in the surface portion (3) may be 0.25 or higher and 0.45 or lower, or the Size Heterogeneity Index, which is an indicator that quantitatively represents the size difference between the primary particles in the center (2) and the surface portion (3) of the cathode active material (100), may be 0.25 or higher and 0.45 or lower. In addition, the Orientation Heterogeneity Index, which is an indicator that quantitatively indicates the deviation of the orientation angle of primary particles on the surface portion (3) of the positive active material (100), may be 6.0° or more and 12.5° or less, or 12.5° or less, and the Grain Boundary Length Density, which is an indicator that quantitatively indicates how densely grain boundaries are distributed within the particles on the surface portion (3) of the positive active material (100), may be 5.576 or more.

[0102] Accordingly, the crystallinity and structural stability of the above-mentioned positive electrode active material (100) can be improved. Therefore, when the above-mentioned positive electrode active material (100) is applied to the above-mentioned lithium secondary battery, the capacity retention rate and initial capacity of the above-mentioned lithium secondary battery can be improved.

[0103] A lithium secondary battery may include a positive electrode having the positive active material (100), a negative electrode spaced apart from the positive electrode, and a solid electrolyte or liquid electrolyte provided between the positive electrode and the negative electrode. For example, the solid electrolyte may be lithium phosphorus sulfur chloride (LPSCl).

[0104] Accordingly, when the lithium secondary battery is subjected to 100 charge / discharge cycles, as described in detail in FIG. 55, the area of ​​microcrack distribution (Areal fraction of microcrack), which is an indicator that quantitatively represents the cracks of particles of the cathode active material (100), can be controlled to 5.0% or less after 100 charge / discharge cycles of the lithium secondary battery to which the cathode active material (100) is applied. In other words, since the primary particles within the cathode active material (100) are densely aligned with a uniform size and a uniform orientation angle, thereby possessing structural stability, the stability of the lithium secondary battery for long-term charge / discharge cycles can be improved.

[0106] Hereinafter, specific experimental examples and characteristic evaluation results of a positive electrode active material according to an embodiment of the present invention and a lithium secondary battery to which the positive electrode active material is applied are described.

[0108] Cathode active material according to comparative examples

[0109] Transition metal hydroxide precursors and lithium sources (LiOH, Li2CO3, A mixture was prepared by mixing LiNO3 or LiCH3COO).

[0110] Then, the above mixture was provided to a heat treatment furnace, and the temperature of the heat treatment furnace was increased from room temperature (25℃) to a heat treatment temperature (600℃ ~ 1,000℃) (2℃ / min) and then heat treated for 10 hours to produce a preliminary cathode active material.

[0111] Then, the above-mentioned preliminary cathode active material was heated from a heat treatment temperature (600℃ ~ 1,000℃) to room temperature (25℃) at a rate of 2℃ / min to produce cathode active materials according to comparative examples as shown in [Table 1] below. (In the process of producing the cathode active materials according to comparative examples, the dopant may have been doped during the preparation process of the precursor, and / or doped before heat treatment at the heat treatment temperature.)

[0113] Cathode active material according to experimental examples

[0114] Transition metal hydroxide precursors and lithium sources (LiOH, Li2CO3, A mixture was prepared by mixing LiNO3 or LiCH3COO).

[0115] The above mixture was provided to a heat treatment furnace, and the temperature of the heat treatment furnace was increased (2℃ / min) from room temperature (25℃) to the lithium melting temperature (250℃ ~ 750℃), and then heat treated (10 minutes ~ 10 hours) to produce a base cathode active material.

[0116] Then, after increasing the temperature of the heat treatment furnace from the lithium melting temperature (250℃ ~ 750℃) to the first heat treatment temperature (300℃ ~ 800℃) (2℃ / min), the base cathode active material was heat-treated (1 hour ~ 24 hours) to produce a first preliminary cathode active material.

[0117] Then, the temperature of the heat treatment furnace was lowered (cooled) from the first heat treatment temperature (300℃ ~ 800℃) to room temperature (25℃) to produce a second preliminary cathode active material.

[0118] Then, after increasing the temperature of the heat treatment furnace from room temperature (25℃) to a second heat treatment temperature (600℃ ~ 1,000℃) (2℃ / min), the second preliminary cathode active material was heat-treated for 10 hours to produce cathode active materials according to experimental examples as shown in [Table 1] below.

[0119] (In the manufacturing process of the cathode active material according to the experimental examples, the dopant may be doped during the manufacturing process of the precursor, doped before the first heat treatment, and / or doped before the second heat treatment.)

[0120] division Precursor Lithium source melting (lithium source) 1st heat treatment Cooling rate Secondary heat treatment Comparison Example 1 NCM950203 -(LiOH) 730℃ / 10h 2℃ / min - Comparison Example 2 NCM950203+Nb 0.5mol%(doping before 1st heat treatment) -(LiOH) 750℃ / 10h 2℃ / min - Comparison Example 3 NCM401248 -(Li2CO3) 920℃ / 10h 2℃ / min - Comparison Example 4 NCM420850+W 0.5mol% (Doping before 1st heat treatment) -(Li2CO3) 950℃ / 10h 2℃ / min - Comparison Example 5 NM5347 -(LiOH) 900℃ / 10h 2℃ / min - Comparison Example 6 NCM601822+W 0.5mol% (doping before 1st heat treatment) -(LiOH) 870℃ / 10h 2℃ / min - Comparison Example 7 NCM800812+Ta 0.5mol% (doping before 1st heat treatment) -(LiOH) 830℃ / 10h 2℃ / min - Comparison Example 8 NCM830710+Ta 0.5mol% (doping before 1st heat treatment) -(LiNO3) 830℃ / 10h 2℃ / min - Comparison Example 9 Mo 1.0 mol% - NCM830710 (precursor preparation stage doping) -(LiOH) 850℃ / 10h 2℃ / min - Comparison Example 10 B 1.0 mol%-NC8812 (precursor preparation stage doping) -(LiOH) 730℃ / 10h 2℃ / min - Comparison Example 11 NC9109+Al 1.0mol%+Zr 1.0mol%(Doping before 1st heat treatment) -(LiOH) 700℃ / 10h 2℃ / min - Comparison Example 12 NCM910504+Ti 2.0mol%(doping before 1st heat treatment) -(LiOH) 770℃ / 10h 2℃ / min - Comparison Example 13 Ti 0.5mol%-NCM910504 (precursor preparation stage doping) -(LiOH) 750℃ / 10h 2℃ / min - Comparison Example 14 NM9109+W 0.5mol% (doping before 1st heat treatment) -(LiOH) 770℃ / 10h 2℃ / min - Comparison Example 15 NCM950203+Nb 0.1mol%(doping before 1st heat treatment) -(LiOH) 750℃ / 10h 2℃ / min - Comparison Example 16 NCM950203+Nb 0.3mol%(doping before 1st heat treatment) -(LiCH3COO) 750℃ / 10h 2℃ / min - Comparison Example 17 Zr 1.0 mol% - NCM950203 (Precursor preparation stage doping) -(LiOH) 750℃ / 10h 2℃ / min - Comparison Example 18 W 1.0 mol%-NCM950203 (precursor preparation stage doping) -(LiOH) 770℃ / 10h 2℃ / min - Comparison Example 19 CSNCM950203 (Concentration Gradient Type) -(LiOH) 730℃ / 10h 2℃ / min - Comparison Example 20 Sb 0.7mol%-NCM950203 (precursor preparation stage doping) -(LiOH) 730℃ / 10h 2℃ / min - Comparison Example 21 NCM950201+Al 1.0mol%+Nb 0.5mol%(Doping before 1st heat treatment) -(LiOH) 750℃ / 10h 2℃ / min - Comparison Example 22 NCM970201+Sb 0.7% (doping before 1st heat treatment) -(LiOH) 730℃ / 10h 2℃ / min - Comparison Example 23 LNO+Nb 0.5% (doping before 1st heat treatment) -(LiOH) 700℃ / 10h 2℃ / min - Experiment Example 1 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) -(LiOH) 550℃ / 5h 2℃ / min 750℃ / 10h Experiment Example 1-1 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) -(LiOH) 550℃ / 5h Quenching 750℃ / 10h Experimental Example 1-2 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) -(LiOH) 550℃ / 5h 5℃ / min 750℃ / 10h Experimental Example 1-3 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) -(LiOH) 550℃ / 5h 0.5℃ / min 750℃ / 10h Experimental Example 1-4 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) -(LiOH) 550℃ / 5h 0.1℃ / min 750℃ / 10h Experiment Example 2 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 450℃ / 2h(LiOH) 550℃ / 5h 2℃ / min 750℃ / 10h Experiment Example 2-1 NCM950203 450℃ / 2h(LiOH) 550℃ / 5h - 730℃ / 10h Experiment Example 2-2 NCM950203 -(LiOH) 550℃ / 5h 2℃ / min 730℃ / 10h Experimental Example 2-3 NCM950203 450℃ / 2h(LiOH) 550℃ / 5h 2℃ / min 730℃ / 10h Experiment Example 3 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 450℃ / 5h(LiOH) 550℃ / 5h 2℃ / min 750℃ / 10h Experiment Example 4 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 450℃ / 10h(LiOH) 550℃ / 5h 2℃ / min 750℃ / 10h Experimental Example 4-1 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 450℃ / 10h(LiOH) 550℃ / 5h 0.5℃ / min 750℃ / 10h Experiment Example 5 NCM401248 700℃ / 10h(LiCO3) 770℃ / 2h 0.5℃ / min 920℃ / 10h Experiment Example 6 NCM420850+W 0.5mol% (Doping before secondary heat treatment) 750℃ / 2h(LiCO3) 800℃ / 5h 2℃ / min 950℃ / 10h Experiment Example 7 NM5347 450℃ / 2h(LiOH) 650℃ / 1h 5℃ / min 900℃ / 10h Experiment Example 8 NCM601822+W 0.5mol% (doping before secondary heat treatment) 450℃ / 2h(LiOH) 600℃ / 5h Quenching 870℃ / 10h Experiment Example 9 NCM800812+Ta 0.5mol% (doping before secondary heat treatment) 450℃ / 5h(LiOH) 580℃ / 10h Quenching 830℃ / 10h Experimental Example 10 NCM830710+Ta 0.5mol% (doping before secondary heat treatment) 300℃ / 5h(LiNO3) 400℃ / 3h 5℃ / min 830℃ / 10h Experimental Example 11 Mo 1.0 mol% - NCM830710 (precursor stage doping) 475℃ / 1h(LiOH) 550℃ / 24h 0.1℃ / min 850℃ / 10h Experiment Example 12 B 1.0 mol%-NC8812 (precursor stage doping) 450℃ / 10h(LiOH) 550℃ / 5h Quenching 730℃ / 10h Experiment Example 13 NC9109+Al 1.0mol%(doping before 1st heat treatment)+Zr 1.0mol%(doping before 2nd heat treatment) 450℃ / 5h(LiOH) 550℃ / 3h 5℃ / min 700℃ / 10h Experimental Example 14 NCM910504+Ti 2.0mol%(doping before secondary heat treatment) 450℃ / 10h(LiOH) 550℃ / 5h Quenching 770℃ / 10h Experimental Example 15 Ti 0.5mol%-NCM910504 (precursor preparation stage doping) 450℃ / 10h(LiOH) 550℃ / 7h Quenching 750℃ / 10h Experimental Example 16 NM9109+W 0.5mol% (doping before secondary heat treatment) 450℃ / 2h(LiOH) 550℃ / 7h 0.5℃ / min 770℃ / 10h Experimental Example 17 NCM950203+Nb 0.1mol%(doping before secondary heat treatment) 450℃ / 5h(LiOH) 550℃ / 5h 2℃ / min 750℃ / 10h Experimental Example 18 NCM950203+Nb 0.3mol%(doping before secondary heat treatment) 250℃ / 10h(LiCH3COO) 300℃ / 5h 2℃ / min 750℃ / 10h Experimental Example 19 Zr 1.0 mol% - NCM950203 (Precursor preparation stage doping) 450℃ / 10h(LiOH) 550℃ / 5h 5℃ / min 750℃ / 10h Experiment Example 20 W 1.0 mol%-NCM950203 (precursor preparation stage doping) 500℃ / 10m(LiOH) 550℃ / 7h 0.1℃ / min 770℃ / 10h Experimental Example 21 CSNCM950203 (Concentration Gradient Type) 500℃ / 2h(LiOH) 550℃ / 5h 0.1℃ / min 730℃ / 10h Experiment Example 22 Sb 0.7mol%-NCM950203 (precursor preparation stage doping) 450℃ / 5h(LiOH) 550℃ / 5h 0.5℃ / min 730℃ / 10h Experiment Example 23 NCM950203 + Al 1.0 mol% (doping before 1st heat treatment) + Nb 0.5 mol% (doping before 2nd heat treatment) 450℃ / 10h(LiOH) 550℃ / 5h 5℃ / min 750℃ / 10h Experiment Example 24 NCM970201+Sb 0.7% (doping before secondary heat treatment) 450℃ / 5h(LiOH) 550℃ / 5h 0.5℃ / min 730℃ / 10h Experimental Example 25 LNO+Nb 0.5% 450℃ / 10h(LiOH) 550℃ / 3h 0.1℃ / min 700℃ / 10h

[0121] FIG. 9 is a diagram illustrating the surface and center of the positive electrode active material according to experimental examples and comparative examples of the present invention.

[0122] Referring to Fig. 9, the surface and center of the positive electrode active material are defined according to experimental examples and comparative examples.

[0123] As can be seen in Fig. 9, the surface portion of the positive electrode active material according to experimental examples and comparative examples is defined as an area within 60% of the radius of the positive electrode active material starting from the surface of the positive electrode active material.

[0124] And, according to experimental examples and comparative examples, the center of the above-mentioned positive electrode active material is defined as an area within 40% of the radius of the above-mentioned positive electrode active material starting from the center of the above-mentioned positive electrode active material.

[0125] The definitions of the center and surface portions of the above-mentioned cathode active material are applied in the same way to the cathode active material according to the embodiments of the present invention.

[0127] FIG. 10 is a diagram illustrating the Size Heterogeneity Index of the cathode active material according to experimental examples and comparative examples of the present invention.

[0128] Referring to Fig. 10, the thickness and length of 100 primary particles were measured using the Image J program in the surface and central regions, respectively, of the cathode active material according to the experimental examples and comparative examples, and the size of the primary particles (r) was calculated using the following [Equation 1]. i ) calculated.

[0129] [Mathematical Formula 1]

[0130]

[0131] And, the overall average size (R) of the primary particles of the above-mentioned cathode active material according to experimental examples and comparative examples. a ) is the area ratio (Areal fraction, W i Considering ), it was calculated as a weighted average as shown in [Equation 2] below.

[0132] [Mathematical Formula 2]

[0133]

[0134] (m = total number of primary particles)

[0135] And, the size heterogeneity index (Size Heterogeneity Index, H) of the above-mentioned cathode active material according to experimental examples and comparative examples s ) is the overall average size (R) of the primary particles of the cathode active material according to experimental examples and comparative examples. a As a relative deviation to ), it was calculated as shown in [Equation 3] below.

[0136] [Mathematical Formula 3]

[0137]

[0138] As can be seen in FIG. 10, the size heterogeneity index (Size Heterogeneity Index, H) of the cathode active material according to experimental examples and comparative examples s It can be seen that ) is an indicator that quantitatively represents the size variation of primary particles on the surface and in the center of the cathode active material according to experimental examples and comparative examples. Accordingly, the Size Heterogeneity Index (H s It can be seen that the smaller ) is, the more uniform the size of the primary particles of the cathode active material. This can be equally applied to the cathode active material according to the embodiment of the present invention.

[0140] FIG. 11 is a diagram illustrating the Orientation Heterogeneity Index of the cathode active material according to experimental examples and comparative examples of the present invention.

[0141] Referring to Fig. 11, in the surface region of the cathode active material according to experimental examples and comparative examples, a minor axis and a major axis intersecting each other at right angles are indicated on 100 primary particles.

[0142] And, the angle between the line connecting the center point of the positive electrode active material and the center point of the primary particle according to the experimental examples and comparative examples and the major axis of the primary particle of the positive electrode active material according to the experimental examples and comparative examples is the orientation angle (θ iIt was defined as ). In addition, the clockwise orientation angle (θ i ) has a positive value (+), and the orientation angle in the counterclockwise direction (θ i ) has a negative value (-).

[0143] And, the orientation heterogeneity index (Orientation Heterogeneity Index, H) of the above-mentioned cathode active material according to experimental examples and comparative examples θ ) is the overall average orientation angle (θ) of the primary particles of the cathode active material according to experimental examples and comparative examples. a As a relative deviation for ), it was calculated as shown in [Equation 4] below.

[0144] [Mathematical Formula 4]

[0145]

[0146] (m = total number of primary particles)

[0147] As can be seen in Fig. 11, the orientation heterogeneity index (H) of the cathode active material according to experimental examples and comparative examples θ It can be seen that ) is an indicator that quantitatively represents the deviation in the orientation angle of primary particles on the surface of the cathode active material according to experimental examples and comparative examples. Accordingly, the Orientation Heterogeneity Index (H θ It can be seen that the smaller ) is, the more uniform the orientation angle of the primary particles of the positive electrode active material. This can be equally applied to the positive electrode active material according to the embodiment of the present invention.

[0149] [Table 2] is a table to compare the performance of half cells with applied cathode active materials for charge / discharge cycles according to experimental examples and comparative examples.

[0150] Referring to [Table 2], half cells with cathode active materials according to Comparative Example 1 (NCM950203), Comparative Example 2 (NCM950203 Nb 0.5%), Experimental Example 1 (NCM950203 Nb 0.5% / 550(5h)), Experimental Example 2 (NCM950203 Nb 0.5% / 450(2h)-550(5h)), Experimental Example 3 (NCM950203 Nb 0.5% / 450(5h)-550(5h)), and Experimental Example 4 (NCM950203 Nb 0.5% / 450(10h)-550(5h)) were subjected to 100 charge / discharge cycles.

[0151] As can be seen in [Table 2], the half cell to which the above-mentioned cathode active material according to Experimental Example 3 and Experimental Example 4 is applied has a high capacity retention rate at 0.5C.

[0152] Accordingly, it can be seen that in the method for manufacturing a positive electrode active material according to an embodiment of the present application, the method of melting the lithium source in the mixture (precursor + lithium source) at the lithium melting temperature for 5 hours or more prior to heat treatment is a method for improving the capacity retention rate of a lithium secondary battery.

[0153] old 0.1 CDisch.Capacity(mAh / g) Efficiency 0.2CCapacity(mAh / g) 0.2C / 0.1C 0.5CCapacity (mAh / g) 0.5C / 0.1C 0.5CCycleRetention compare example 1 238.8 96.3% 231.8 97.1% 221.0 92.6% 83.2% compare example 2 236.4 96.4% 233.7 98.9% 222.0 93.9% 88.3% experiment example 1 238.8 96.1% 234.9 98.3% 223.5 93.6% 91.7% experiment example 2 239.3 96.8% 235.5 98.4% 225.6 94.3% 93.0% experiment example 3 240.4 96.6% 236.8 98.3% 225.6 93.6% 95.0% experiment example 4 239.9 96.7% 236.1 98.4% 226.1 94.2% 94.9%

[0155] FIG. 12 is a graph showing an SEM image of a positive electrode active material according to Comparative Example 1 of the present invention, a particle size deviation between the surface and center of the primary particles, and an orientation angle deviation between the surface of the primary particles.

[0156] Referring to FIG. 12, a cross-section of the cathode active material according to Comparative Example 1 was photographed using SEM. Then, by the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active material according to Comparative Example 1 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 3] below.

[0157] As can be seen in FIG. 12 and [Table 3], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Comparative Example 1 s ) is 0.495, and the primary particle size non-uniformity index (H) in the center s ) is 0.471, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 14.57.

[0158] Contents Average Standard dev. Heterogeneity Particle size (Surface) 281.85 142.86 0.495 Particle size (Center) 187.56 98.33 0.471 Orientation angle 1.46 29.66 14.57

[0160] FIG. 13 is a graph showing an SEM image of a positive electrode active material according to Comparative Example 2 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0161] Referring to FIG. 13, a cross-section of the cathode active material according to Comparative Example 2 was photographed using SEM. Then, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Comparative Example 2 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 4] below.

[0162] As can be seen in FIG. 13 and [Table 4], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Comparative Example 2 s ) is 0.421, and the primary particle size non-uniformity index (H) in the center s ) is 0.400, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 13.24.

[0163] Contents Average Standard dev. Heterogeneity Particle size (Surface) 207.48 90.57 0.421 Particle size (Center) 140.06 59.21 0.400 Orientation angle 5.33 24.43 13.24

[0165] Figure 14 is a graph showing an SEM image of the cathode active material according to Experimental Example 1 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles.

[0166] Referring to FIG. 14, a cross-section of the cathode active material according to Experimental Example 1 was photographed using SEM. Then, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 1 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 5] below.

[0167] As can be seen in FIG. 14 and [Table 5], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 1 s ) is 0.376, and the primary particle size non-uniformity index (H) in the center s ) is 0.378, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 12.01.

[0168] Contents Average Standard dev. Heterogeneity Particle size (Surface) 200.54 85.93 0.376 Particle size (Center) 160.24 58.25 0.378 Orientation angle 0.95 19.98 12.01

[0170] Figure 15 is a graph showing an SEM image of the cathode active material according to Experimental Example 2 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles.

[0171] Referring to FIG. 15, a cross-section of the cathode active material according to Experimental Example 2 was photographed using SEM. Then, using the method described in detail in FIGs. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 2 s) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 6] below.

[0172] As can be seen in FIG. 15 and [Table 6], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 2 s ) is 0.349, and the primary particle size non-uniformity index (H) in the center s ) is 0.347, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 11.27.

[0173] Contents Average Standard dev. Heterogeneity Particle size (Surface) 211.68 64.87 0.349 Particle size (Center) 140.81 59.95 0.347 Orientation angle -3.36 17.68 11.27

[0175] Figure 16 is a graph showing an SEM image of the cathode active material according to Experimental Example 3 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles.

[0176] Referring to FIG. 16, a cross-section of the cathode active material according to Experimental Example 3 was photographed using SEM. Then, using the method described in detail in FIGs. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active material according to Experimental Example 3 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 7] below.

[0177] As can be seen in FIG. 16 and [Table 7], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 3 s ) is 0.303, and the primary particle size non-uniformity index (H) in the center s ) is 0.333, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 10.22.

[0178] Contents Average Standard dev. Heterogeneity Particle size (Surface) 195.36 63.34 0.303 Particle size (Center) 140.84 42.84 0.333 Orientation angle 1.08 14.96 10.22

[0180] Figure 17 is a graph showing an SEM image of the cathode active material according to Experimental Example 4 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles.

[0181] Referring to FIG. 17, a cross-section of the cathode active material according to Experimental Example 4 was photographed using SEM. Then, by the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 4 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 8] below.

[0182] As can be seen in FIG. 17 and [Table 8], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 4 s ) is 0.303, and the primary particle size non-uniformity index (H) in the center s ) is 0.333, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 8.49.

[0183] Contents Average Standard dev. Heterogeneity Particle size (Surface) 194.94 50.37 0.290 Particle size (Center) 134.98 42.64 0.308 Orientation angle -0.08 14.57 8.49

[0185] FIG. 18 shows the performance of a half cell with an anode active material applied according to experimental examples and comparative examples of the present invention, and the size heterogeneity index (Size Heterogeneity Index, H) of the primary particles of the anode active material. s ) and Orientation Heterogeneity Index (H θ This is a graph for comparing relationships.

[0186] Referring to Fig. 18 and [Table 2] together, the 0.5C initial discharge capacity and capacity at 0.5C of half cells with cathode active materials according to Comparative Example 1 (NCM950203 1-step), Comparative Example 2 (NCM950203+Nb 0.5% 1-step), Experimental Example 1 (NCM950203+Nb 0.5% 2-step (550 (5h))), Experimental Example 2 (NCM950203+Nb 0.5% 2-step (450 (2h) 550 (5h))), Experimental Example 3 (NCM950203+Nb 0.5% 2-step (450 (5h) 550 (5h))), and Experimental Example 4 (NCM950203+Nb 0.5% 2-step (450 (10h) 550 (5h)) Retention rate (100 charge / discharge cycles) and

[0187] In [Tables 3] to [8], the Size Heterogeneity Index (H) of primary particles on the surface and in the center of the cathode active material according to Comparative Example 1 (NCM950203 1-step), Comparative Example 2 (NCM950203+Nb 0.5% 1-step), Experimental Example 1 (NCM950203+Nb 0.5% 2-step (550(5h)), Experimental Example 2 (NCM950203+Nb 0.5% 2-step (450(2h) 550(5h)), Experimental Example 3 (NCM950203+Nb 0.5% 2-step (450(5h) 550(5h)), and Experimental Example 4 (NCM950203+Nb 0.5% 2-step (450(10h) 550(5h)) s ) and the Orientation Heterogeneity Index (H θ The relationship of ) was compared.

[0188] As can be seen in Fig. 18, the initial discharge capacity and capacity retention rate of the half cell to which the above-mentioned positive active material according to Experimental Example 4 is applied are the best.

[0189] Accordingly, in the method for manufacturing a positive electrode active material according to an embodiment of the present application, the method of melting the lithium source in the mixture (precursor + lithium source) at the lithium melting temperature for 5 hours or more prior to heat treatment is a method that not only improves the capacity retention rate of the lithium secondary battery but also improves the initial capacity.

[0190] Alternatively, in the method for manufacturing a positive electrode active material according to an embodiment of the present application, the method of melting the lithium source in the mixture (precursor + lithium source) at the lithium melting temperature for 10 hours or more prior to heat treatment is a method that not only improves the capacity retention rate of the lithium secondary battery but also improves the initial capacity.

[0192] [Table 9] is a table to compare the performance of half cells with applied cathode active materials for charge / discharge cycles according to experimental examples and comparative examples.

[0193] Referring to [Table 9], Comparative Example 1 (NCM950203, 730℃(10h), 2℃ / min), Comparative Example 2 (NCM950203 Nb 0.5%, 750℃(10h), 2℃ / min), Experimental Example 1 (NCM950203 Nb 0.5%, 550℃(5h), 2℃ / min, 750℃(10h)), Experimental Example 1-1 (NCM950203 Nb 0.5% 550℃(5h), Quenching, 750℃(10h)), Experimental Example 1-2 (NCM950203 Nb 0.5%, 550℃(5h), 5℃ / min, 750℃(10h)), Experimental Example 1-3 (NCM950203 Nb 0.5%, Half cells with positive electrode active materials according to Experimental Example 1-4 (NCM950203 Nb 0.5%, 550℃(5h), 0.1℃ / min, 750℃(10h)) and Experimental Example 1-4 (550℃(5h), 0.1℃ / min, 750℃(10h)) were subjected to 100 charge / discharge cycles.

[0194] As can be seen in [Table 9], the half cell with the above-mentioned cathode active material according to Experimental Examples 1-3 has the highest capacity retention rate at 0.5C.

[0195] Accordingly, it can be seen that in the method for manufacturing a cathode active material according to an embodiment of the present application, the method of controlling the cooling rate of the first pre-cathode active material to be greater than 0.1℃ / min and less than 2.0℃ / min is a method for improving the capacity retention rate of a lithium secondary battery.

[0196] old 0.1 CDisch.Capacity(mAh / g) Efficiency 0.2CCapacity(mAh / g) 0.2C / 0.1C 0.5CCapacity (mAh / g) 0.5C / 0.1C 0.5CCycleRetention compare example 1 238.8 96.3% 231.8 97.1% 221.0 92.6% 83.2% compare example 2 236.4 96.4% 233.7 98.9% 222.0 93.9% 88.3% experiment example 1 238.8 96.1% 234.9 98.3% 223.5 93.6% 91.6% Example 1-1 239.8 97.5% 235.6 98.3% 223.4 93.2% 89.9% Example 1-2 241.1 97.6% 237.8 98.6% 223.5 92.7% 90.5% experiment example 1-3 241.1 97.6% 236.8 98.2% 225.7 93.6% 94.0% experiment example 1-4 240.9 97.4% 237.6 98.6% 225.5 93.6% 93.0%

[0198] FIG. 19 is a graph showing an SEM image of the cathode active material according to Experimental Example 1-1 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles.

[0199] Referring to FIG. 19, a cross-section of the cathode active material according to Experimental Example 1-1 was photographed using SEM. Then, using the method described in detail in FIGs. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 1-1 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 10] below.

[0200] As can be seen in FIG. 19 and [Table 10], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 1-1 s ) is 0.395, and the primary particle size non-uniformity index (H) in the center s ) is 0.384, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 11.82.

[0201] Contents Average Standard dev. Heterogeneity Particle size (Surface) 172.30 74.27 0.395 Particle size (Center) 120.31 59.76 0.384 Orientation angle 1.73 24.94 11.82

[0203] FIG. 20 is a graph showing SEM images of the cathode active material according to Experimental Example 1-2 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0204] Referring to FIG. 20, a cross-section of the cathode active material according to Experimental Example 1-2 was photographed using SEM. Then, using the method described in detail in FIGs. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 1-2 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 11] below.

[0205] As can be seen in FIG. 20 and [Table 11], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 1-2 s ) is 0.389, and the primary particle size non-uniformity index (H) of the center s ) is 0.380, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 11.76.

[0206] Contents Average Standard dev. Heterogeneity Particle size (Surface) 148.61 60.85 0.389 Particle size (Center) 100.16 43.95 0.380 Orientation angle -0.66 19.99 11.76

[0208] FIG. 21 is a graph showing SEM images of the cathode active material according to Experimental Examples 1-3 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0209] Referring to FIG. 21, a cross-section of the cathode active material according to Experimental Example 1-3 was photographed using SEM. Then, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 1-3 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 12] below.

[0210] As can be seen in FIG. 21 and [Table 12], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Examples 1-3 s ) is 0.314, and the primary particle size non-uniformity index (H) in the center s ) is 0.305, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 7.76.

[0211] Contents Average Standard dev. Heterogeneity Particle size (Surface) 134.50 39.02 0.314 Particle size (Center) 84.75 29.35 0.305 Orientation angle -1.76 12.32 7.76

[0213] FIG. 22 is a graph showing SEM images of the cathode active material according to Experimental Examples 1-4 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0214] Referring to FIG. 22, a cross-section of the cathode active material according to Experimental Example 1-4 was photographed using SEM. Then, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 1-4 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 13] below.

[0215] As can be seen in FIG. 22 and [Table 13], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Examples 1-4 s ) is 0.355, and the primary particle size non-uniformity index (H) of the center s ) is 0.329, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 8.46.

[0216] Contents Average Standard dev. Heterogeneity Particle size (Surface) 146.55 55.18 0.355 Particle size (Center) 102.84 30.06 0.329 Orientation angle -0.16 14.29 8.46

[0218] FIG. 23 shows the performance of a half cell with an anode active material applied according to experimental examples and comparative examples of the present invention and the size heterogeneity index (Size Heterogeneity Index, H) of the primary particles of the anode active material. s ) and Orientation Heterogeneity Index (H θ This is a graph for comparing relationships.

[0219] Referring to Fig. 23 and [Table 9], Comparative Example 1 (NCM950203, 730℃(10h), 2℃ / min), Comparative Example 2 (NCM950203 Nb 0.5%, 750℃(10h), 2℃ / min), Experimental Example 1 (NCM950203 Nb 0.5%, 550℃(5h), 2℃ / min, 750℃(10h)), Experimental Example 1-1 (NCM950203 Nb 0.5% 550℃(5h), Quenching, 750℃(10h)), Experimental Example 1-2 (NCM950203 Nb 0.5%, 550℃(5h), 5℃ / min, 750℃(10h)), Experimental Example 1-3 (NCM950203 Nb 0.5%, The 0.5C initial discharge capacity and capacity retention rate at 0.5C (100 charge / discharge cycles) of a half cell with cathode active material according to Experimental Example 1-4 (NCM950203 Nb 0.5%, 550℃(5h), 0.1℃ / min, 750℃(10h)), and

[0220] In Tables 3 to 5 and Tables 10 to 13, Comparative Example 1 (NCM950203 1-step), Comparative Example 2 (NCM950203+Nb 0.5% 1-step), Experimental Example 1 (NCM950203+Nb 0.5% 2-step (decreasing temperature at 2℃ / min after 550°C (5h) heat treatment), Experimental Example 1-1 (NCM950203+Nb 0.5% 2-step (decreasing temperature at 0.5℃ / min after 550°C (5h) heat treatment), Experimental Example 1-2 (NCM950203+Nb 0.5% 2-step (decreasing temperature at 5℃ / min after 550°C (5h) heat treatment), Experimental Example 1-3 (NCM950203+Nb 0.5% 2-step (decreasing temperature at 0.5℃ / min after 550°C (5h) heat treatment), and the size heterogeneity index (Size Heterogeneity Index, H) of primary particles on the surface and center of the above cathode active material according to Experimental Examples 1-4 (NCM950203+Nb 0.5% 2-step (550°C (5h) heat treatment followed by 0.1°C / min cooling) s ) and the Orientation Heterogeneity Index (H θ The relationship of ) was compared.

[0221] As can be seen in Fig. 23, the initial discharge capacity and capacity retention rate of the half cell to which the above-mentioned positive active material according to Experimental Examples 1-3 is applied are the best.

[0222] Accordingly, in the method for manufacturing a positive electrode active material according to an embodiment of the present application, the method of controlling the cooling rate of the first pre-positive electrode active material to be greater than 0.1℃ / min and less than 2.0℃ / min is a method for improving the capacity retention rate of a lithium secondary battery.

[0224] [Table 14] is a table for comparing the performance of half cells with applied positive electrode active materials according to experimental examples and comparative examples of the present invention regarding charge / discharge cycles.

[0225] Referring to [Table 14], Comparative Example 1 (1 step of 2.0℃ / min cooling after NCM950203 heat treatment), Comparative Example 2 (1 step of 2.0℃ / min cooling after NCM950203 0.5% Nb heat treatment), Experimental Example 1 (2.0℃ / min cooling after NCM950203 0.5% Nb / 550 (5h) heat treatment), Experimental Example 4 (2.0℃ / min cooling after NCM950203 0.5% Nb / 450 (10h)-550 (5h) heat treatment), Experimental Examples 1-3 (0.5℃ / min cooling after NCM950203 0.5% Nb / 550 (5h) heat treatment), and Experimental Example 4-1 (NCM950203 Nb After heat treatment at 0.5% / 450 (10h)-550 (5h), a half cell with a positive electrode active material applied at 0.5% / min lower temperature was subjected to 100 charge / discharge cycles.

[0226] As can be seen in [Table 14], the half cell with the above-mentioned positive active material according to Experimental Example 4-1 has the highest capacity retention rate at 0.5C.

[0227] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C 0.5CC Cycle Retention Comparison Example 1 238.8 96.3% 231.8 97.1% 221.0 92.6% 83.2% Comparison Example 2 236.4 96.4% 233.7 98.9% 222.0 93.9% 88.3% Experiment Example 1 238.8 96.1% 234.9 98.3% 223.5 93.6% 91.7% Experiment Example 4 239.9 96.7% 236.1 98.4% 226.1 94.2% 94.9% Experimental Example 1-3 241.1 97.6% 236.8 98.2% 225.7 93.6% 94.0% Experimental Example 4-1 241.3 97.7% 237.4 98.4% 226.5 93.9% 95.8%

[0229] FIG. 24 is a graph showing an SEM image of the cathode active material according to Experimental Example 4-1 of the present invention, the particle size deviation between the surface and center of the primary particles, and the orientation angle deviation of the surface of the primary particles.

[0230] Referring to FIG. 24, a cross-section of the cathode active material according to Experimental Example 4-1 was photographed using SEM. Then, using the method described in detail in FIGs. 9 to 11, the Size Heterogeneity Index (H) of the primary particles in the surface and center of the cathode active material according to Experimental Example 4-1 s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 15] below.

[0231] As can be seen in Fig. 24 and [Table 15], the size non-uniformity index (H) of the primary particles on the surface of the cathode active material according to Experimental Example 4-1 s ) is 0.251, and the primary particle size non-uniformity index (H) in the center s ) is 0.287, and the culture heterogeneity index (H) of the primary particles on the surface θ It can be seen that ) is 7.72.

[0232] Contents Average Standard dev. Heterogeneity Particle size (Surface) 151.21 39.46 0.251 Particle size (Center) 97.71 23.29 0.287 Orientation angle -2.24 9.62 7.72

[0234] FIG. 25 shows the performance of a half cell with an anode active material applied according to experimental examples and comparative examples of the present invention and the size heterogeneity index (Size Heterogeneity Index, H) of the primary particles of the anode active material. s ) and Orientation Heterogeneity Index (H θ This is a graph for comparing relationships.

[0235] Referring to Fig. 25 and [Table 14], according to Comparative Example 1 (NCM950203 1 step), Comparative Example 2 (NCM950203 Nb 0.5% 1 step), Experimental Example 1 (NCM950203 Nb 0.5% / 550 (5h) heat treatment followed by 2.0℃ / min cooling), Experimental Example 4 (NCM950203 Nb 0.5% / 450 (10h)-550 (5h) heat treatment followed by 2.0℃ / min cooling), Experimental Examples 1-3 (NCM950203 Nb 0.5% / 550 (5h) heat treatment followed by 0.5℃ / min cooling), and Experimental Example 4-1 (NCM950203 Nb 0.5% / 450 (10h)-550 (5h) heat treatment followed by 0.5℃ / min cooling) The 0.5C initial discharge capacity and capacity retention rate at 0.5C (100 charge / discharge cycles) of a half cell with cathode active material, and

[0236] In Tables 3 through 5, Table 8, Table 12, and Table 15, Comparative Example 1 (NCM950203 1-step), Comparative Example 2 (NCM950203+Nb 0.5% 1-step), Experimental Example 1 (NCM950203 Nb 0.5% / 2.0℃ / min cooling after 550°C (5h) heat treatment), Experimental Example 4 (NCM950203 Nb 0.5% / 2.0℃ / min cooling after 450°C (10h)-550°C (5h) heat treatment), Experimental Example 1-3 (NCM950203+Nb 0.5% 2-step (0.5℃ / min cooling after 550°C (5h) heat treatment)), and Experimental Example 4-1 (NCM950203+Nb 0.5% 2-step Size Heterogeneity Index (H) of primary particles on the surface and center of the above-mentioned cathode active material according to (450 (10h) 550 (5h) heat treatment followed by cooling at 0.5℃ / min) s ) and the Orientation Heterogeneity Index (H θ The relationship of ) was compared.

[0237] As can be seen in Fig. 25, the initial discharge capacity and capacity retention rate of the half cell to which the above-mentioned positive active material according to Experimental Example 4-1 is applied are the best.

[0239] [Table 16] is a table for comparing the performance of half cells with positive electrode active materials according to experimental examples of the present invention and comparative example 1 during charge / discharge cycles.

[0240] Referring to [Table 16], half cells with positive electrode active materials according to Comparative Example 1 (NCM950203 730℃ firing 1 step), Experimental Example 2-1 (NCM950203 450 (2h) 550 (5h), cooling omitted, 730℃ firing), Experimental Example 2-2 (NCM950203 550 (5h), 2℃ / min cooling after heat treatment, 730℃ firing), and Experimental Example 2-3 (NCM950203 450 (2h) 550 (5h), 2℃ / min cooling after heat treatment, 730℃ firing) were subjected to 100 charge / discharge cycles.

[0241] As can be seen in [Table 16], the half cell with the above-mentioned positive active material according to Experimental Example 2-3 has the highest capacity retention rate and initial discharge capacity at 0.5C.

[0242] Accordingly, in the method for manufacturing a cathode active material according to the embodiment of the present application, it can be seen that a cathode active material that improves the capacity and capacity retention rate of a lithium secondary battery is provided by melting a lithium source in a mixture at a lithium melting temperature and cooling a first preliminary cathode active material. That is, in the method for manufacturing a cathode active material, it can be seen that both the process of manufacturing a base cathode active material by melting a lithium source in a mixture at a lithium melting temperature and the process of manufacturing a second preliminary cathode active material by cooling a first preliminary cathode active material must be performed.

[0243] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C 0.5CC Cycle Retention Comparison Example 1 239.8 96.3% 232.8 97.1% 221.0 92.1% 88.7% Experiment Example 2-1 238.7 95.6% 229.9 96.3% 216.9 90.9% 83.2% Experiment Example 2-2 239.1 96.5% 233.3 97.6% 221.5 92.6% 88.9% Experimental Example 2-3 240.4 97.0% 237.5 98.8% 223.1 92.8% 90.1%

[0245] FIG. 26 is a graph showing SEM images of the cathode active material according to Comparative Example 3 and Experimental Example 5 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0246] Referring to FIG. 26, cross-sections of the cathode active materials according to Comparative Example 3 (step 1) and Experimental Example 5 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 3 (step 1) and Experimental Example 5 (step 2) were applied, and the results are summarized in [Table 17] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 3 (step 1) and Experimental Example 5 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 18] below.

[0247] As can be seen in Figure 26, [Table 17], and [Table 18], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 5 is superior to that of the half cell with the cathode active material according to Comparative Example 3.

[0248] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 5 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 3. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 5 are more uniform than those of the cathode active material according to Comparative Example 3.

[0249] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C 1.0 C Papacity (mAh / g) 1.0C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 3 223.1 91.7% 210.3 94.2% 198.3 88.9% 188.4 84.5% 100 94.1% Experiment Example 5 226.2 92.5% 214.7 94.9% 203.8 90.1% 195.2 86.3% 100 95.1%

[0250] division average standard deviation Non-uniformity index Comparison Example 3 Surface primary particle size (nm) 240.5 80.47 0.469 Central primary particle size (nm) 170.54 57.06 0.452 Surface primary particle orientation angle (°) -3.24 26.12 13.89 Experiment Example 5 Surface primary particle size (nm) 224.5 71.06 0.398 Central primary particle size (nm) 160.42 53.19 0.41 Surface primary particle orientation angle (°) 2.41 21.21 11.15

[0252] FIG. 27 is a graph showing SEM images of the cathode active material according to Comparative Example 4 and Experimental Example 6 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0253] Referring to FIG. 27, cross-sections of the cathode active materials according to Comparative Example 4 (step 1) and Experimental Example 6 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 4 (step 1) and Experimental Example 6 (step 2) were applied, and the results are summarized in [Table 19] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 4 (step 1) and Experimental Example 6 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 20] below.

[0254] As can be seen in Fig. 27, [Table 19], and [Table 20], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 5 is superior to that of the half cell with the cathode active material according to Comparative Example 4.

[0255] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 5 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 4. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 5 are more uniform than those of the cathode active material according to Comparative Example 4.

[0256] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C 1.0 C Papacity (mAh / g) 1.0C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 4 221.1 92.1% 210.3 94.7% 198.4 89.3% 188.5 84.9% 100 95.4% Experiment Example 6 224.9 92.3% 212.6 96.7% 200.5 89.2% 189.4 84.2% 100 96.1%

[0257] division average standard deviation Non-uniformity index Comparison Example 4 Surface primary particle size (nm) 221.45 82.46 0.475 Central primary particle size (nm) 164.11 61.1 0.427 Surface primary particle orientation angle (°) 2.49 28.12 14.51 Experiment Example 6 Surface primary particle size (nm) 198.15 64.51 0.369 Central primary particle size (nm) 174.21 56.94 0.387 Surface primary particle orientation angle (°) -0.35 16.21 9.45

[0259] FIG. 28 is a graph showing SEM images of the cathode active material according to Comparative Example 5 and Experimental Example 7 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0260] Referring to FIG. 28, cross-sections of the cathode active materials according to Comparative Example 5 (step 1) and Experimental Example 7 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 5 (step 1) and Experimental Example 7 (step 2) were applied, and the results are summarized in [Table 21] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 5 (step 1) and Experimental Example 7 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 22] below.

[0261] As can be seen in Fig. 28, [Table 21], and [Table 22], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 7 is superior to that of the half cell with the cathode active material according to Comparative Example 5.

[0262] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 7 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 5. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 7 are more uniform than those of the cathode active material according to Comparative Example 5.

[0263] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 5 202.5 98.8% 199.4 98.4% 191.1 94.3% 100 81.1% Experiment Example 7 204.3 99.0% 200.5 98.1% 195.1 95.5% 100 86.7%

[0264] division average standard deviation Non-uniformity index Comparison Example 5 Surface primary particle size (nm) 202.77 83.38 0.469 Central primary particle size (nm) 147.14 55.64 0.458 Surface primary particle orientation angle (°) -2.767 17.67 13.13 Experiment Example 7 Surface primary particle size (nm) 193.11 78.51 0.411 Central primary particle size (nm) 138.45 45.23 0.401 Surface primary particle orientation angle (°) 0.5 14.74 9.12

[0266] FIG. 29 is a graph showing SEM images of the cathode active material according to Comparative Example 6 and Experimental Example 8 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0267] Referring to FIG. 29, cross-sections of the cathode active materials according to Comparative Example 6 (step 1) and Experimental Example 8 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 6 (step 1) and Experimental Example 8 (step 2) were applied, and the results are summarized in [Table 23] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 6 (step 1) and Experimental Example 8 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 24] below.

[0268] As can be seen in Fig. 29, [Table 23], and [Table 24], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 8 is superior to that of the half cell with the cathode active material according to Comparative Example 6.

[0269] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 8 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 6. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 8 are more uniform than those of the cathode active material according to Comparative Example 6.

[0270] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 6 212.7 99.2% 209.2 98.3% 200.0 94.0% 100 95.2% Experiment Example 8 215.2 99.2% 211.6 98.3% 204.0 94.8% 100 96.0%

[0271] division average standard deviation Non-uniformity index Comparison Example 6 Surface primary particle size (nm) 221.54 83.04 0.469 Central primary particle size (nm) 156.65 66.30 0.452 Surface primary particle orientation angle (°) 1.105 23.59 12.35 Experiment Example 8 Surface primary particle size (nm) 205.45 74.12 0.367 Central primary particle size (nm) 147.51 59.16 0.39 Surface primary particle orientation angle (°) 0.08 12.78 8.34

[0273] FIG. 30 is a graph showing SEM images of the cathode active material according to Comparative Example 7 and Experimental Example 9 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0274] Referring to FIG. 30, cross-sections of the cathode active materials according to Comparative Example 7 (step 1) and Experimental Example 9 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 7 (step 1) and Experimental Example 9 (step 2) were applied, and the results are summarized in [Table 25] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 7 (step 1) and Experimental Example 9 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 26] below.

[0275] As can be seen in Fig. 30, [Table 25], and [Table 26], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 9 is superior to that of the half cell with the cathode active material according to Comparative Example 7.

[0276] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 9 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 7. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 9 are more uniform than those of the cathode active material according to Comparative Example 7.

[0277] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 7 209.6 91.8% 205.9 98.3% 196.3 93.6% 100 93.6% Experiment Example 9 213.5 92.8% 208.9 97.9% 199.3 93.3% 100 98.3%

[0278] division average standard deviation Non-uniformity index Comparison Example 7 Surface primary particle size (nm) 214.54 75.15 0.491 Central primary particle size (nm) 153.54 52.56 0.442 Surface primary particle orientation angle (°) -1.05 25.56 13.18 Experiment Example 9 Surface primary particle size (nm) 174.95 54.69 0.365 Central primary particle size (nm) 144.13 41.75 0.372 Surface primary particle orientation angle (°) 0.73 14.75 9.34

[0280] FIG. 31 is a graph showing SEM images of the cathode active material according to Comparative Example 8 and Experimental Example 10 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0281] Referring to FIG. 31, cross-sections of the cathode active materials according to Comparative Example 8 (step 1) and Experimental Example 10 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 8 (step 1) and Experimental Example 10 (step 2) were applied, and the results are summarized in [Table 27] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 8 (step 1) and Experimental Example 10 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 28] below.

[0282] As can be seen from Figure 31, [Table 27], and [Table 28], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 10 is superior to that of the half cell with the cathode active material according to Comparative Example 8.

[0283] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 10 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 8. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 10 are more uniform than those of the cathode active material according to Comparative Example 8.

[0284] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 8 218.5 96.3% 213.9 97.9% 204.3 93.5% 100 91.5% Experimental Example 10 218.8 96.4% 214.0 97.8% 206.8 94.5% 100 95.5%

[0285] division average standard deviation Non-uniformity index Comparison Example 8 Surface primary particle size (nm) 251.74 93.36 0.46 Central primary particle size (nm) 155.45 64.92 0.425 Surface primary particle orientation angle (°) -0.63 27.99 14.93 Experimental Example 10 Surface primary particle size (nm) 214.24 70.62 0.385 Central primary particle size (nm) 141.45 51.74 0.379 Surface primary particle orientation angle (°) 1.56 19.23 10.84

[0287] FIG. 32 is a graph showing SEM images of the cathode active material according to Comparative Example 9 and Experimental Example 11 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0288] Referring to FIG. 32, cross-sections of the cathode active materials according to Comparative Example 9 (step 1) and Experimental Example 11 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 9 (step 1) and Experimental Example 11 (step 2) were applied, and the results are summarized in [Table 29] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 9 (step 1) and Experimental Example 11 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 30] below.

[0289] As can be seen in Fig. 32, [Table 29], and [Table 30], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 11 is superior to that of the half cell with the cathode active material according to Comparative Example 9.

[0290] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 11 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 9. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 11 are more uniform than those of the cathode active material according to Comparative Example 9.

[0291] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 9 216.6 96.1% 212.0 97.9% 204.0 94.2% 100 91.8% Experimental Example 11 219.5 97.0% 215.3 98.1% 207.4 94.5% 100 96.3%

[0292] division average standard deviation Non-uniformity index Comparison Example 9 Surface primary particle size (nm) 174.94 36.05 0.381 Central primary particle size (nm) 112.26 29.35 0.342 Surface primary particle orientation angle (°) 2.62 23.03 12.45 Experimental Example 11 Surface primary particle size (nm) 159.45 30.09 0.311 Central primary particle size (nm) 95.84 26.31 0.289 Surface primary particle orientation angle (°) 0.77 12.23 6.98

[0294] FIG. 33 is a graph showing SEM images of the cathode active material according to Comparative Example 10 and Experimental Example 12 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0295] Referring to FIG. 33, cross-sections of the cathode active materials according to Comparative Example 10 (step 1) and Experimental Example 12 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 10 (step 1) and Experimental Example 12 (step 2) were applied, and the results are summarized in [Table 31] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 10 (step 1) and Experimental Example 12 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 32] below.

[0296] As can be seen in Fig. 33, [Table 31], and [Table 32], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 12 is superior to that of the half cell with the cathode active material according to Comparative Example 10.

[0297] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 12 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 10. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 12 are more uniform than those of the cathode active material according to Comparative Example 10.

[0298] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 10 235.7 94.5% 222.9 94.6% 208.8 88.6% 100 88.5% Experiment Example 12 236.5 94.5% 223.3 94.4% 213.1 90.1% 100 90.9%

[0299] division average standard deviation Non-uniformity index Comparison Example 10 Surface primary particle size (nm) 284.46 169.42 0.47 Central primary particle size (nm) 158.91 49.63 0.455 Surface primary particle orientation angle (°) 5.61 27.4 15.5 Experiment Example 12 Surface primary particle size (nm) 232.48 92.31 0.385 Central primary particle size (nm) 135.54 42.33 0.342 Surface primary particle orientation angle (°) 0.45 14.15 8.38

[0301] FIG. 34 is a graph showing SEM images of the cathode active material according to Comparative Example 11 and Experimental Example 13 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0302] Referring to FIG. 34, cross-sections of the cathode active materials according to Comparative Example 11 (step 1) and Experimental Example 13 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 11 (step 1) and Experimental Example 13 (step 2) were applied, and the results are summarized in [Table 33] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 11 (step 1) and Experimental Example 13 (step 2) s ) and the Orientation Heterogeneity Index (H θ) is summarized in [Table 34] below.

[0303] As can be seen from Figure 34, [Table 33], and [Table 34], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 13 is superior to that of the half cell with the cathode active material according to Comparative Example 11.

[0304] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 13 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 11. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 13 are more uniform than those of the cathode active material according to Comparative Example 11.

[0305] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 11 229.8 95.1% 223.2 97.1% 212.3 92.4% 100 94.1% Experiment Example 13 232.9 95.8% 226.1 97.1% 215.2 92.4% 100 97.1%

[0306] division average standard deviation Non-uniformity index Comparison Example 11 Surface primary particle size (nm) 247.91 88.13 0.456 Central primary particle size (nm) 152.71 63.54 0.452 Surface primary particle orientation angle (°) 1.11 25.56 15.37 Experiment Example 13 Surface primary particle size (nm) 205.93 65.03 0.379 Central primary particle size (nm) 135.09 55.94 0.393 Surface primary particle orientation angle (°) 0.73 18.19 10.75

[0308] FIG. 35 is a graph showing SEM images of the cathode active material according to Comparative Example 12 and Experimental Example 14 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0309] Referring to FIG. 35, cross-sections of the cathode active materials according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2) were applied, and the results are summarized in [Table 35] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2) s) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 36] below.

[0310] As can be seen in Fig. 35, [Table 35], and [Table 36], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 14 is superior to that of the half cell with the cathode active material according to Comparative Example 12.

[0311] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 14 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 12. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 14 are more uniform than those of the cathode active material according to Comparative Example 12.

[0312] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 12 227.7 95.4% 221.4 97.2% 211.7 92.9% 100 91.5% Experimental Example 14 230.1 96.3% 224.6 97.6% 215.1 93.5% 100 94.0%

[0313] division average standard deviation Non-uniformity index Comparison Example 12 Surface primary particle size (nm) 296.14 158.3 0.469 Central primary particle size (nm) 143.56 49.71 0.461 Surface primary particle orientation angle (°) 1.10 28.51 15.48 Experimental Example 14 Surface primary particle size (nm) 254.07 83.27 0.378 Central primary particle size (nm) 129.54 39.45 0.381 Surface primary particle orientation angle (°) 0.89 14.26 8.35

[0315] FIG. 36 is a graph showing SEM images of the cathode active material according to Comparative Example 13 and Experimental Example 15 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0316] Referring to FIG. 36, cross-sections of the cathode active materials according to Comparative Example 13 (step 1) and Experimental Example 15 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 13 (step 1) and Experimental Example 15 (step 2) were applied, and the results are summarized in [Table 37] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 13 (step 1) and Experimental Example 15 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 38] below.

[0317] As can be seen in Fig. 36, [Table 37], and [Table 38], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 15 is superior to that of the half cell with the cathode active material according to Comparative Example 13.

[0318] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 15 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 13. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 15 are more uniform than those of the cathode active material according to Comparative Example 13.

[0319] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 13 228.7 96.4% 219.3 95.9% 207.9 90.9% 100 86.8% Experimental Example 15 230.0 96.6% 222.9 96.9% 211.1 91.8% 100 90.5%

[0320] division average standard deviation Non-uniformity index Comparison Example 13 Surface primary particle size (nm) 206.5 73.79 0.433 Central primary particle size (nm) 141.6 55.1 0.37 Surface primary particle orientation angle (°) -2.6 24.2 12.53 Experimental Example 15 Surface primary particle size (nm) 168.4 60.17 0.275 Central primary particle size (nm) 120.9 43.13 0.319 Surface primary particle orientation angle (°) -0.79 15.98 8.77

[0322] FIG. 37 is a graph showing SEM images of the cathode active material according to Comparative Example 14 and Experimental Example 16 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0323] Referring to FIG. 37, cross-sections of the cathode active materials according to Comparative Example 14 (step 1) and Experimental Example 16 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 14 (step 1) and Experimental Example 16 (step 2) were applied, and the results are summarized in [Table 39] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 14 (step 1) and Experimental Example 16 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 40] below.

[0324] As can be seen in Fig. 37, [Table 39], and [Table 40], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 16 is superior to that of the half cell with the cathode active material according to Comparative Example 14.

[0325] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 16 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 14. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 16 are more uniform than those of the cathode active material according to Comparative Example 14.

[0326] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 14 232.9 99.3% 226.0 97.0% 216.3 92.9% 100 90.2% Experimental Example 16 234.8 99.5% 227.2 96.7% 218.4 93.0% 100 92.5%

[0327] division average standard deviation Non-uniformity index Comparison Example 14 Surface primary particle size (nm) 212.87 65.46 0.401 Central primary particle size (nm) 151.32 50.84 0.38 Surface primary particle orientation angle (°) 1.56 21.62 12.47 Experimental Example 16 Surface primary particle size (nm) 180.91 52.17 0.263 Central primary particle size (nm) 117.95 40.10 0.309 Surface primary particle orientation angle (°) 1.37 13.76 8.71

[0329] FIG. 38 is a graph showing SEM images of the cathode active material according to Comparative Example 1 and Experimental Examples 2-3 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0330] Referring to FIG. 38, cross-sections of the cathode active materials according to Comparative Example 1 (step 1) and Experimental Example 2-3 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 1 (step 1) and Experimental Example 2-3 (step 2) were applied, and the results are summarized in [Table 41] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 1 (step 1) and Experimental Example 2-3 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 42] below.

[0331] As can be seen in Fig. 38, [Table 41], and [Table 42], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 2-3 is superior to that of the half cell with the cathode active material according to Comparative Example 1.

[0332] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 2-3 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 1. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 2-3 are more uniform than those of the cathode active material according to Comparative Example 1.

[0333] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 1 239.8 96.3% 232.8 97.1% 221.0 92.1% 100 88.7% Experimental Example 2-3 240.4 97.0% 237.5 98.8% 223.1 92.8% 100 90.1%

[0334] division average standard deviation Non-uniformity index Comparison Example 1 Surface primary particle size (nm) 281.85 142.86 0.495 Central primary particle size (nm) 187.56 98.33 0.471 Surface primary particle orientation angle (°) 1.46 29.66 14.57 Experimental Example 2-3 Surface primary particle size (nm) 275.64 117.65 0.448 Central primary particle size (nm) 181.57 76.55 0.426 Surface primary particle orientation angle (°) -0.08 24.00 12.13

[0336] FIG. 39 is a graph showing SEM images of the cathode active material according to Comparative Example 15 and Experimental Example 17 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0337] Referring to FIG. 39, cross-sections of the cathode active materials according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2) were applied, and the results are summarized in [Table 43] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 44] below.

[0338] As can be seen from Fig. 39, [Table 43], and [Table 44], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 17 is superior to that of the half cell with the cathode active material according to Comparative Example 15.

[0339] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 17 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 15. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 17 are more uniform than those of the cathode active material according to Comparative Example 15.

[0340] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 15 240.7 96.4% 233.7 97.1% 222.2 92.3% 100 85.0% Experimental Example 17 240.9 96.5% 234.6 97.4% 222.8 92.5% 100 92.5%

[0341] division average standard deviation Non-uniformity index Comparison Example 15 Surface primary particle size (nm) 250.51 124.67 0.482 Central primary particle size (nm) 170.54 93.26 0.458 Surface primary particle orientation angle (°) -3.13 24.80 12.81 Experimental Example 17 Surface primary particle size (nm) 235.45 88.08 0.423 Central primary particle size (nm) 154.47 84.03 0.412 Surface primary particle orientation angle (°) 4.335 21.57 11.83

[0343] FIG. 40 is a graph showing SEM images of the cathode active material according to Comparative Example 16 and Experimental Example 18 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0344] Referring to FIG. 40, cross-sections of the cathode active materials according to Comparative Example 16 (step 1) and Experimental Example 18 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 16 (step 1) and Experimental Example 18 (step 2) were applied, and the results are summarized in [Table 45] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 16 (step 1) and Experimental Example 18 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 46] below.

[0345] As can be seen in Fig. 40, [Table 45], and [Table 46], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 18 is superior to that of the half cell with the cathode active material according to Comparative Example 16.

[0346] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 18 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 16. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 18 are more uniform than those of the cathode active material according to Comparative Example 16.

[0347] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 16 240.6 97.3% 237.0 98.5% 222.1 92.3% 100 87.3% Experimental Example 18 241.5 97.4% 238.4 98.7% 223.4 92.5% 100 94.2%

[0348] division average standard deviation Non-uniformity index Comparison Example 16 Surface primary particle size (nm) 215.61 124.14 0.454 Central primary particle size (nm) 150.65 97.22 0.435 Surface primary particle orientation angle (°) 2.56 24.59 12.13 Experimental Example 18 Surface primary particle size (nm) 204.46 94.18 0.390 Central primary particle size (nm) 145.19 74.96 0.394 Surface primary particle orientation angle (°) 0.16 22.73 11.13

[0350] FIG. 41 is a graph showing SEM images of the cathode active material according to Comparative Example 17 and Experimental Example 19 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0351] Referring to FIG. 41, cross-sections of the cathode active materials according to Comparative Example 17 (step 1) and Experimental Example 19 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 17 (step 1) and Experimental Example 19 (step 2) were applied, and the results are summarized in [Table 47] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 17 (step 1) and Experimental Example 19 (step 2) s ) and the Orientation Heterogeneity Index (H θ) is summarized in [Table 48] below.

[0352] As can be seen from Figure 41, [Table 47], and [Table 48], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 19 is superior to that of the half cell with the cathode active material according to Comparative Example 17.

[0353] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 19 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 17. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 19 are more uniform than those of the cathode active material according to Comparative Example 17.

[0354] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 17 238.8 97.5% 235.7 98.7% 223.1 93.4% 100 90.2% Experimental Example 19 240.9 97.8% 237.5 98.6% 225.0 93.5% 100 92.2%

[0355] division average standard deviation Non-uniformity index Comparison Example 17 Surface primary particle size (nm) 301.94 167.84 0.398 Central primary particle size (nm) 175.36 58.85 0.44 Surface primary particle orientation angle (°) -0.48 27.99 14.12 Experimental Example 19 Surface primary particle size (nm) 255.66 91.36 0.34 Central primary particle size (nm) 164.51 50.96 0.331 Surface primary particle orientation angle (°) -0.22 14.58 9.04

[0357] FIG. 42 is a graph showing SEM images of the cathode active material according to Comparative Example 18 and Experimental Example 20 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0358] Referring to FIG. 42, cross-sections of the cathode active materials according to Comparative Example 18 (step 1) and Experimental Example 20 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 18 (step 1) and Experimental Example 20 (step 2) were applied, and the results are summarized in [Table 49] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 18 (step 1) and Experimental Example 20 (step 2) s) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 50] below.

[0359] As can be seen in Fig. 42, [Table 49], and [Table 50], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 20 is superior to that of the half cell with the cathode active material according to Comparative Example 18.

[0360] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 20 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 18. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 20 are more uniform than those of the cathode active material according to Comparative Example 18.

[0361] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 18 236.9 95.5% 231.9 97.9% 222.8 94.0% 100 93.3% Experiment Example 20 237.1 95.6% 232.9 98.3% 223.0 94.1% 100 96.1%

[0362] division average standard deviation Non-uniformity index Comparison Example 18 Surface primary particle size (nm) 164.43 35.31 0.371 Central primary particle size (nm) 101.15 27.22 0.379 Surface primary particle orientation angle (°) -0.67 24.54 12.94 Experiment Example 20 Surface primary particle size (nm) 154.20 30.09 0.308 Central primary particle size (nm) 93.73 24.33 0.294 Surface primary particle orientation angle (°) 0.40 9.99 6.24

[0364] FIG. 43 is a graph showing SEM images of the cathode active material according to Comparative Example 19 and Experimental Example 21 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0365] Referring to FIG. 43, cross-sections of the cathode active materials according to Comparative Example 19 (step 1) and Experimental Example 21 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 19 (step 1) and Experimental Example 21 (step 2) were applied, and the results are summarized in [Table 51] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 19 (step 1) and Experimental Example 21 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 52] below.

[0366] As can be seen in Fig. 43, [Table 51], and [Table 52], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 21 is superior to that of the half cell with the cathode active material according to Comparative Example 19.

[0367] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 21 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 19. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 21 are more uniform than those of the cathode active material according to Comparative Example 19.

[0368] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 19 240.5 97.1% 237.5 98.8% 226.6 94.2% 100 88.7% Experimental Example 21 241.3 97.9% 238.5 98.9% 227.7 94.4% 100 95.3%

[0369] division average standard deviation Non-uniformity index Comparison Example 19 Surface primary particle size (nm) 227.56 109.82 0.406 Central primary particle size (nm) 138.37 61.26 0.417 Surface primary particle orientation angle (°) -1.46 21.95 12.43 Experimental Example 21 Surface primary particle size (nm) 172.78 38.87 0.353 Central primary particle size (nm) 124.18 34.35 0.357 Surface primary particle orientation angle (°) -2.45 17.83 9.38

[0371] FIG. 44 is a graph showing SEM images of the cathode active material according to Comparative Example 20 and Experimental Example 22 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0372] Referring to FIG. 44, cross-sections of the cathode active materials according to Comparative Example 20 (step 1) and Experimental Example 22 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 20 (step 1) and Experimental Example 22 (step 2) were applied, and the results are summarized in [Table 53] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 20 (step 1) and Experimental Example 22 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 54] below.

[0373] As can be seen from Figure 44, [Table 53], and [Table 54], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 22 is superior to that of the half cell with the cathode active material according to Comparative Example 20.

[0374] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 22 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 20. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 22 are more uniform than those of the cathode active material according to Comparative Example 20.

[0375] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 20 238.9 96.3% 230.1 97.1% 225.0 94.2% 100 93.3% Experiment Example 22 241.4 98.0% 236.9 98.1% 227.1 94.1% 100 95.6%

[0376] division average standard deviation Non-uniformity index Comparison Example 20 Surface primary particle size (nm) 198.25 61.54 0.397 Central primary particle size (nm) 131.39 51.07 0.38 Surface primary particle orientation angle (°) 2.15 24.91 12.64 Experiment Example 22 Surface primary particle size (nm) 124.54 54.75 0.25 Central primary particle size (nm) 93.34 28.94 0.261 Surface primary particle orientation angle (°) -2.23 11.69 6.02

[0378] FIG. 45 is a graph showing SEM images of the cathode active material according to Comparative Example 21 and Experimental Example 23 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0379] Referring to FIG. 45, cross-sections of the cathode active materials according to Comparative Example 21 (step 1) and Experimental Example 23 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 21 (step 1) and Experimental Example 23 (step 2) were applied, and the results are summarized in [Table 55] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 21 (step 1) and Experimental Example 23 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 56] below.

[0380] As can be seen in Fig. 45, [Table 55], and [Table 56], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 23 is superior to that of the half cell with the cathode active material according to Comparative Example 21.

[0381] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 23 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 21. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 23 are more uniform than those of the cathode active material according to Comparative Example 21.

[0382] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 21 245.2 98.0% 240.9 98.2% 236.7 96.5% 100 93.6% Experiment Example 23 247.2 98.6% 244.4 98.9% 238.1 96.3% 100 94.9%

[0383] division average standard deviation Non-uniformity index Comparison Example 21 Surface primary particle size (nm) 308.00 152.54 0.411 Central primary particle size (nm) 182.91 61.38 0.438 Surface primary particle orientation angle (°) -1.47 29.96 14.33 Experiment Example 23 Surface primary particle size (nm) 250.49 92.14 0.337 Central primary particle size (nm) 156.38 52.56 0.335 Surface primary particle orientation angle (°) 3.83 17.59 9.35

[0385] FIG. 46 is a graph showing SEM images of the cathode active material according to Comparative Example 22 and Experimental Example 24 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0386] Referring to FIG. 46, cross-sections of the cathode active materials according to Comparative Example 22 (step 1) and Experimental Example 24 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 22 (step 1) and Experimental Example 24 (step 2) were applied, and the results are summarized in [Table 57] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 22 (step 1) and Experimental Example 24 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 58] below.

[0387] As can be seen from Figure 46, [Table 57], and [Table 58], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 24 is superior to that of the half cell with the cathode active material according to Comparative Example 22.

[0388] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 24 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 22. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 24 are more uniform than those of the cathode active material according to Comparative Example 22.

[0389] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 22 241.0 96.6% 235.5 97.7% 226.0 93.8% 100 87.8% Experiment Example 24 242.3 96.7% 237.9 98.2% 231.2 95.4% 100 92.5%

[0390] division average standard deviation Non-uniformity index Comparison Example 22 Surface primary particle size (nm) 200.26 65.18 0.402 Central primary particle size (nm) 140.21 50.21 0.394 Surface primary particle orientation angle (°) -3.67 23.72 12.71 Experiment Example 24 Surface primary particle size (nm) 149.28 60.70 0.249 Central primary particle size (nm) 89.71 32.11 0.273 Surface primary particle orientation angle (°) 1.87 12.89 6.54

[0392] FIG. 47 is a graph showing SEM images of the cathode active material according to Comparative Example 23 and Experimental Example 25 of the present invention, particle size deviation between the surface and center of the primary particles, and orientation angle deviation of the surface of the primary particles.

[0393] Referring to FIG. 47, cross-sections of the cathode active materials according to Comparative Example 23 (step 1) and Experimental Example 25 (step 2) were photographed using SEM. Then, 100 charge / discharge cycles were performed on half cells to which the cathode active materials according to Comparative Example 23 (step 1) and Experimental Example 25 (step 2) were applied, and the results are summarized in [Table 59] below. Furthermore, using the method described in detail in FIG. 9 to 11, the Size Heterogeneity Index (H) of the primary particles on the surface and in the center of the cathode active materials according to Comparative Example 23 (step 1) and Experimental Example 25 (step 2) s ) and the Orientation Heterogeneity Index (H θ ) is summarized in [Table 60] below.

[0394] As can be seen in Figure 47, [Table 59], and [Table 60], the performance (capacity, capacity retention rate) of the half cell with the cathode active material according to Experimental Example 25 is superior to that of the half cell with the cathode active material according to Comparative Example 23.

[0395] This factor is interpreted to be due to the fact that the size non-uniformity index of the primary particles in the surface and center of the cathode active material according to Experimental Example 25 and the orientation non-uniformity index of the surface portion are lower than those of the cathode active material according to Comparative Example 23. In other words, it can be seen that the size and orientation angle of the primary particles of the cathode active material according to Experimental Example 25 are more uniform than those of the cathode active material according to Comparative Example 23.

[0396] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.2 CPacity(mAh / g) 0.2C / 0.1C 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 23 247.2 96.2% 243.8 98.6% 232.9 93.9% 100 83.7% Experimental Example 25 249.5 95.8% 246.4 98.8% 240.3 96.3% 100 86.1%

[0397] division average standard deviation Non-uniformity index Comparison Example 23 Surface primary particle size (nm) 302.71 118.36 0.378 Central primary particle size (nm) 186.90 134.93 0.401 Surface primary particle orientation angle (°) 4.40 24.61 14.38 Experiment Example 50 Surface primary particle size (nm) 242.35 105.43 0.283 Central primary particle size (nm) 176.64 84.54 0.312 Surface primary particle orientation angle (°) -2.57 11.72 8.35

[0399] FIGS. 48 to 50 are graphs showing the strength of the positive electrode active material according to comparative examples and experimental examples of the present invention.

[0400] Referring to Fig. 48, the strength of the cathode active material particles according to Comparative Example 1 (step 1) and Experimental Example 2-3 (step 2) was measured and shown in a graph. Referring to Fig. 49, the strength of the cathode active material particles according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2) was measured and shown in a graph. Referring to Fig. 50, the strength of the cathode active material particles according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2) was measured and shown in a graph. The results are summarized in [Table 61] below.

[0401] As can be seen in Figure 48 and [Table 61], the particle strength of the cathode active material according to Experimental Examples 2-3 is stronger than that of the cathode active material according to Comparative Example 1.

[0402] As can be seen in Figure 49 and [Table 61], the particle strength of the cathode active material according to Experimental Example 17 is stronger than that of the cathode active material according to Comparative Example 15.

[0403] As can be seen in Figure 50 and [Table 61], the particle strength of the cathode active material according to Experimental Example 14 is stronger than that of the cathode active material according to Comparative Example 12.

[0404] Overall, it can be seen that the particle strength of the cathode active material according to the experimental example is stronger than that of the cathode active material according to the comparative example having the same chemical composition.

[0405] This factor is interpreted to be due to the fact that, unlike the method of manufacturing the cathode active material according to the comparative examples, the method of manufacturing the cathode active material according to the experimental examples sequentially performs a process of melting the lithium source in a mixture (precursor + lithium source) (450°C or higher and 500°C or lower when the lithium source is LiOH, 700°C or higher and 750°C or lower when the lithium source is Li2CO3, 250°C or higher and 300°C or lower when the lithium source is LiNO3, and 10 minutes or more and 10 hours or less), a primary heat treatment process (300°C or higher and 800°C or lower, 1 hour or more and 24 hours or less), and a cooling process (Quenching ~ 0.1°C / min cooling).

[0406] division Particle strength (MPa) average standard deviation Comparison Example 1 74.5 26.6 Experimental Example 2-3 105.8 26.8 Comparison Example 15 83.8 19.6 Experimental Example 17 116.5 17.7 Comparison Example 12 99.5 18.6 Comparison Example 14 132.8 21.6

[0408] FIG. 51 is a diagram illustrating the grain boundary length density of the cathode active material according to experimental examples and comparative examples of the present invention.

[0409] Referring to Fig. 51, the major axis (a) and minor axis (b) lengths of the primary particles on the surface of the cathode active material according to experimental examples and comparative examples were measured using the Image J program, and assuming the shape of the primary particles to be elliptical, the circumference (P) of the primary particles was calculated using [Equation 5] below. i) calculated.

[0410] [Mathematical Formula 5]

[0411]

[0412] In addition, the grain boundary length density of the primary particles of the cathode active material according to the experimental examples and comparative examples was calculated using [Equation 6] below. In [Equation 6], Total Area is the surface area of ​​the cathode active material according to the experimental examples and comparative examples, and the reason for multiplying Total Area by 2 is to consider the bilateral boundary of the elliptical approximation of the primary particles.

[0413] [Mathematical Formula 6]

[0414]

[0415] As can be seen in Fig. 51, the grain boundary length density of the primary particles of the cathode active material according to experimental examples and comparative examples is an indicator that quantitatively represents how densely the grain boundaries are distributed within the particles of the cathode active material. Accordingly, it can be seen that the greater the grain boundary length density of the cathode active material, the denser the distribution of primary particles within the cathode active material.

[0417] FIGS. 52 to 54 are cross-sectional SEM images for comparing the grain boundary length density of the cathode active material according to comparative examples and experimental examples of the present invention.

[0418] Referring to Fig. 52, the grain boundary length density (GBLD) of the cathode active material according to Comparative Example 1 (step 1) and Experimental Examples 2-3 (step 2) was measured using the method described in Fig. 51. Referring to Fig. 53, the grain boundary length density (GBLD) of the cathode active material according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2) was measured using the method described in Fig. 51. Referring to Fig. 54, the grain boundary length density (GBLD) of the cathode active material according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2) was measured using the method described in Fig. 51. The results are summarized in [Table 62] below.

[0419] As can be seen in Figure 52 and [Table 62], the boundary length density of the particles of the cathode active material according to Experimental Examples 2-3 is greater than that of the cathode active material according to Comparative Example 1.

[0420] As can be seen in Figure 53 and [Table 62], the boundary length density of the particles of the cathode active material according to Experimental Example 17 is greater than that of the cathode active material according to Comparative Example 15.

[0421] As can be seen in Figure 54 and [Table 62], the boundary length density of the particles of the cathode active material according to Experimental Example 14 is greater than that of the cathode active material according to Comparative Example 12.

[0422] In summary, it can be seen that the boundary length density of the particles of the cathode active material according to the experimental example is greater than that of the cathode active material according to the comparative example having the same chemical composition. In other words, it can be seen that the primary particles of the cathode active material according to the experimental example are more densely distributed than those of the cathode active material according to the comparative example.

[0423] This factor is interpreted to be due to the fact that, unlike the method of manufacturing the cathode active material according to the comparative examples, the method of manufacturing the cathode active material according to the experimental examples sequentially performs a process of melting the lithium source in a mixture (precursor + lithium source) (450°C or higher and 500°C or lower when the lithium source is LiOH, 700°C or higher and 750°C or lower when the lithium source is Li2CO3, 250°C or higher and 300°C or lower when the lithium source is LiNO3, and 10 minutes or more and 10 hours or less), a primary heat treatment process (300°C or higher and 800°C or lower, 1 hour or more and 24 hours or less), and a cooling process (Quenching ~ 0.1°C / min cooling).

[0424] division Boundary Length Density (GBLD) Comparison Example 1 5.178 Experimental Example 2-3 5.576 Comparison Example 15 5.271 Experimental Example 17 7.534 Comparison Example 12 5.312 Comparison Example 14 8.041

[0426] FIG. 55 is a diagram for explaining the distribution of the area of ​​microcracks (Areal fraction of microcrack) of a positive electrode active material after performing charge / discharge cycles of a secondary battery to which a positive electrode active material according to experimental examples and comparative examples of the present invention is applied.

[0427] Referring to FIG. 55, after performing 100 charge / discharge cycles of a lithium secondary battery with a positive electrode active material according to experimental examples and comparative examples, the total area (A) of the positive electrode active material particles using an Image J program particle ) is measured and the area excluding cracks in the above cathode active material particles (A no crack By measuring ), the crack area (A microcracks = A particle - A no crack ) calculated.

[0428] Then, using [Equation 7] below, the distribution of the area of ​​microcracks in the positive electrode active material according to experimental examples and comparative examples after the charge / discharge cycle of the lithium secondary battery (Areal fraction of microcrack) was calculated.

[0429] [Mathematical Formula 7]

[0430]

[0431] As can be seen in Fig. 55, the distribution of the area of ​​microcracks of the cathode active material according to experimental examples and comparative examples after charge / discharge cycles of the lithium secondary battery (areal fraction of microcrack) is an indicator that quantitatively represents the crack area of ​​the particles of the cathode active material after 100 charge / discharge cycles of the lithium secondary battery to which the cathode active material according to experimental examples and comparative examples is applied. Accordingly, it can be seen that the smaller the distribution of the area of ​​microcracks, the better the mechanical stability of the cathode active material with respect to charge / discharge cycles of the lithium secondary battery.

[0433] FIGS. 56 to 58 are cross-sectional SEM images for comparing the real fraction of microcrack distribution of a positive electrode active material after performing charge / discharge cycles of a half cell with a positive electrode active material according to experimental examples and comparative examples.

[0434] Referring to FIG. 56, after performing 100 charge / discharge cycles on a half cell with a positive electrode active material according to Comparative Example 1 (step 1) and Experimental Example 2-3 (step 2), the area distribution of microcracks according to Comparative Example 1 (step 1) and Experimental Example 2-3 (step 2) was calculated using the method described in FIG. 55. Referring to FIG. 57, after performing 100 charge / discharge cycles on a half cell with a positive electrode active material according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2), the area distribution of microcracks according to Comparative Example 15 (step 1) and Experimental Example 17 (step 2) was calculated using the method described in FIG. 55. Referring to FIG. 58, after performing 100 charge / discharge cycles on half cells with the positive electrode active materials according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2), the area distribution of the positive electrode active materials according to Comparative Example 12 (step 1) and Experimental Example 14 (step 2) (Areal fraction of microcrack) was calculated using the method described in FIG. 55. The results are summarized in [Table 63] below.

[0435] As can be seen in Figure 56 and [Table 63], the distribution of the microcrack area of ​​the particles of the cathode active material according to Experimental Examples 2-3 is smaller than that of the cathode active material according to Comparative Example 1.

[0436] As can be seen in Figure 57 and [Table 63], the distribution of the microcrack area of ​​the particles of the cathode active material according to Experimental Example 17 is smaller than that of the cathode active material according to Comparative Example 15.

[0437] As can be seen in Figure 58 and [Table 63], the distribution of the microcrack area of ​​the particles of the cathode active material according to Experimental Example 14 is smaller than that of the cathode active material according to Comparative Example 12.

[0438] Overall, it can be seen that the area of ​​microcracks in the particles of the cathode active material according to the experimental example is smaller than that of the cathode active material according to the comparative example having the same chemical composition. In other words, it can be seen that the cathode active material according to the experimental example has superior mechanical stability against charge / discharge cycles compared to the cathode active material according to the comparative example.

[0439] This factor is interpreted to be due to the fact that, unlike the method of manufacturing the cathode active material according to the comparative examples, the method of manufacturing the cathode active material according to the experimental examples sequentially performs a process of melting the lithium source in a mixture (precursor + lithium source) (450°C or higher and 500°C or lower when the lithium source is LiOH, 700°C or higher and 750°C or lower when the lithium source is Li2CO3, 250°C or higher and 300°C or lower when the lithium source is LiNO3, and 10 minutes or more and 10 hours or less), a primary heat treatment process (300°C or higher and 800°C or lower, 1 hour or more and 24 hours or less), and a cooling process (Quenching ~ 0.1°C / min cooling).

[0440] division Areal fraction of microcrack area distribution Comparison Example 1 9.7% Experimental Example 2-3 5.0% Comparison Example 15 8.7% Experimental Example 17 4.8% Comparison Example 12 6.2% Comparison Example 14 3.5%

[0442] [Table 64] is a table for comparing the performance of half cells (all-solid-state batteries) to which the positive active material according to comparative examples and experimental examples of the present invention is applied.

[0443] Referring to [Table 64], half cells (all-solid-state batteries) with positive electrode active materials according to Comparative Example 11, Comparative Example 18, Comparative Example 22, Experimental Example 13, Experimental Example 20, and Experimental Example 24 were subjected to 100 charge / discharge cycles (3.0V~4.3V, solid electrolyte (LPSCl), 30℃).

[0444] As can be seen in [Table 64], when comparing the performance of the half cells with the above-mentioned positive active material according to Comparative Example 11 and Experimental Example 13, it can be seen that the half cell with the above-mentioned positive active material according to Experimental Example 13 has a higher initial capacity and a superior capacity retention rate compared to the half cell with the above-mentioned positive active material according to Comparative Example 11.

[0445] And, when comparing the performance of the half cell with the above-mentioned positive active material according to Comparative Example 18 and Experimental Example 20, it can be seen that the half cell with the above-mentioned positive active material according to Experimental Example 20 has a higher initial capacity and a superior capacity retention rate than the half cell with the above-mentioned positive active material according to Comparative Example 18.

[0446] And, when comparing the performance of the half cell with the above-mentioned positive active material according to Comparative Example 22 and Experimental Example 24, it can be seen that the half cell with the above-mentioned positive active material according to Experimental Example 24 has a higher initial capacity and a superior capacity retention rate than the half cell with the above-mentioned positive active material according to Comparative Example 22.

[0447] This factor is interpreted to be due to the fact that, unlike the method of manufacturing the cathode active material according to comparative examples as described in detail in FIG. 48, the method of manufacturing the cathode active material according to experimental examples sequentially performs a process of melting the lithium source in a mixture (precursor + lithium source) (450°C or higher and 500°C or lower when the lithium source is LiOH, 700°C or higher and 750°C or lower when the lithium source is Li2CO3, 250°C or higher and 300°C or lower when the lithium source is LiNO3, and 10 minutes or more and 10 hours or less), a first heat treatment process (300°C or higher and 800°C or lower, 1 hour or more and 24 hours or less), and a cooling process (Quenching ~ 0.1°C / min cooling).

[0448] division 0.1 CDisch.Capa(mAh / g) Efficiency 0.5 CPacity (mAh / g) 0.5C / 0.1C Cycle 0.5CC Cycle Retention Comparison Example 11 213.2 86.4% 191.3 86.4% 100 63.4% Experiment Example 13 226.0 89.8% 206.1 91.2% 100 82.5% Comparison Example 18 227.8 93.5% 196.5 86.3% 100 92.0% Experiment Example 20 232.0 93.7% 207.7 89.5% 100 93.6% Comparison Example 22 222.3 84.9% 192.7 86.7 100 86.2% Experiment Example 24 238.5 87.5% 206.8 86.7% 100 87.7%

[0450] [Table 65] shows the average particle size, average orientation angle, average absolute orientation angle, and average aspect ratio of the surface portion of the cathode active material according to comparative examples and experimental examples of the present invention.

[0451] Referring to [Table 65], the average size, average orientation angle, average absolute orientation angle, and average aspect ratio of primary particles on the surface of the cathode active material according to the comparative examples and experimental examples of [Table 1] and a commercially available cathode active material (POSCO, EASPRING Tech.) were compared.

[0452] division Precursor primary particles on the surface Average size (nm) (standard deviation) Mean orientation angle (°) (standard deviation) Mean Absolute Value Orientation Angle (°) (Standard Deviation) Mean aspect ratio (standard deviation) Comparison Example 1 NCM950203 281.85(142.86) 1.46(29.66) 15.60(9.61) 2.07(0.93) Comparison Example 2 NCM950203+Nb 0.5mol%(doping before 1st heat treatment) 207.48(90.57) 5.33(24.43) 9.95(7.30) 2.18(0.81) Comparison Example 3 NCM401248 240.5(80.47) -3.24(26.12) 11.87(9.36) 2.61(1.22) Comparison Example 4 NCM420850+W 0.5mol% (doping before 1st heat treatment) 221.45(82.46) 2.49(28.12) 12.03(9.56) 3.02(1.43) Comparison Example 5 NM5347 202.77(83.38) -2.77(17.67) 9.64(8.42) 1.92(0.77) Comparison Example 6 NCM601822+W 0.5mol% (doping before 1st heat treatment) 221.54(83.04) 1.11(23.59) 9.30(6.60) 2.05(0.82) Comparison Example 7 NCM800812+Ta 0.5mol% (doping before 1st heat treatment) 214.54(75.15) -1.05(25.56) 8.34(7.76) 1.93(0.8) Comparison Example 8 NCM830710+Ta 0.5mol% (doping before 1st heat treatment) 251.74(93.36) -0.63(27.99) 14.61(9.15) 1.66(0.66) Comparison Example 9 Mo 1.0 mol% - NCM830710 (precursor preparation stage doping) 174.94(36.05) 2.62(23.03) 11.30(8.27) 1.65(0.66) Comparison Example 10 B 1.0 mol%-NC8812 (precursor preparation stage doping) 284.46(169.42) 5.61(27.4) 12.47(8.42) 2.78(1.11) Comparison Example 11 NC9109+Al 1.0mol%+Zr 1.0mol%(Doping before 1st heat treatment) 247.91(88.13) 1.11(25.56) 11.81(9.59) 1.60(0.64) Comparison Example 12 NCM910504+Ti 2.0mol%(doping before 1st heat treatment) 296.14(158.3) 1.10(28.51) 11.02(9.32) 1.63(0.65) Comparison Example 13 Ti 0.5mol%-NCM910504 (precursor preparation stage doping) 206.5(73.79) -2.6(24.2) 13.80(6.70) 1.91(0.77) Comparison Example 14 NM9109+W 0.5mol% (doping before 1st heat treatment) 212.87(65.46) 1.56(21.62) 11.34(8.58) 1.73(0.69) Comparison Example 15 NCM950203+Nb 0.1mol%(doping before 1st heat treatment) 250.51(124.67) -3.13(24.80) 13.19(9.67) 2.03(0.81) Comparison Example 16 NCM950203+Nb 0.3mol%(doping before 1st heat treatment) 215.61(124.14) 2.56(24.59) 12.20(8.54) 2.02(0.81) Comparison Example 17 Zr 1.0 mol% - NCM950203 (Precursor preparation stage doping) 301.94(167.84) -0.48(27.99) 11.45(8.80) 1.52(0.61) Comparison Example 18 W 1.0 mol%-NCM950203 (precursor preparation stage doping) 164.43(35.31) -0.67(24.54) 10.26(6.62) 1.54(0.62) Comparison Example 19 CSNCM950203 (Concentration Gradient Type) 227.56(109.82) -1.46(21.95) 8.86(6.48) 1.79(0.72) Comparison Example 20 Sb 0.7mol%-NCM950203 (precursor preparation stage doping) 198.25(61.54) 2.15(24.91) 8.97(6.66) 1.69(0.68) Comparison Example 21 NCM950201+Al 1.0mol%+Nb 0.5mol%(Doping before 1st heat treatment) 308.00(152.54) -1.47(29.96) 9.43(8.08) 1.52(0.61) Comparison Example 22 NCM970201+Sb 0.7% (doping before 1st heat treatment) 200.26(65.18) -3.67(23.72) 11.85(7.17) 1.70(0.68) Comparison Example 23 LNO+Nb 0.5% (doping before 1st heat treatment) 302.71(118.36) 4.40(24.61) 9.29(8.15) 1.41(0.56) Experiment Example 1 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 200.54(85.93) 0.95(19.98) 11.23(8.16) 2.23(0.66) Experiment Example 1-1 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 172.30(74.27) 1.73(24.94) 6.38(5.96) 2.27(1.07) Experimental Example 1-2 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 148.61(60.85) -0.66(19.99) 10.54(8.03) 2.33(0.84) Experimental Example 1-3 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 134.50(39.02) -1.76(12.32) 6.56(5.89) 2.70(1.22) Experimental Example 1-4 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 146.55(55.18) -0.16(14.29) 5.51(4.99) 2.27(0.64) Experiment Example 2 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 211.68(64.87) -3.36(17.68) 9.58(6.91) 2.43(1.15) Experimental Example 2-3 NCM950203 275.64(117.65) -0.08(24.00) 8.08(6.31) 2.24(0.82) Experiment Example 3 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 195.36(63.34) 1.08(14.96) 6.35(6.63) 2.59(1.17) Experiment Example 4 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 194.94(50.37) -0.08(14.57) 5.13(4.31) 2.58(1.12) Experimental Example 4-1 NCM950203+Nb 0.5mol%(doping before secondary heat treatment) 151.21(39.46) -2.24(9.62) 6.73(1.78) 2.64(0.82) Experiment Example 5 NCM401248 224.5(71.06) 2.41(21.21) 10.89(9.23) 2.72(1.32) Experiment Example 6 NCM420850+W 0.5mol% (Doping before secondary heat treatment) 198.15(64.51) -0.35(16.21) 8.89(8.52) 3.13(1.47) Experiment Example 7 NM5347 193.11(78.51) 0.50(14.74) 9.12(7.67) 2.43(0.97) Experiment Example 8 NCM601822+W 0.5mol% (doping before secondary heat treatment) 205.45(74.12) 0.08(12.78) 6.40(2.12) 2.37(0.95) Experiment Example 9 NCM800812+Ta 0.5mol% (doping before secondary heat treatment) 174.95(54.69) 0.73(14.75) 5.99(5.41) 2.34(0.84) Experimental Example 10 NCM830710+Ta 0.5mol% (doping before secondary heat treatment) 214.24(70.62) 1.56(19.23) 11.04(8.49) 2.11(0.76) Experimental Example 11 Mo 1.0 mol% - NCM830710 (precursor stage doping) 159.45(30.09) 0.77(12.23) 4.78(4.32) 2.40(0.96) Experiment Example 12 B 1.0 mol%-NC8812 (precursor stage doping) 232.48(92.31) 0.45(14.15) 8.15(6.82) 3.25(1.30) Experiment Example 13 NC9109+Al 1.0mol%(doping before 1st heat treatment)+Zr 1.0mol%(doping before 2nd heat treatment) 205.93(65.03) 0.73(18.19) 11.26(8.67) 2.13(0.76) Experimental Example 14 NCM910504+Ti 2.0mol%(doping before secondary heat treatment) 254.07(83.27) 0.89(14.26) 9.08(8.19) 2.01(0.98) Experimental Example 15 Ti 0.5mol%-NCM910504 (precursor preparation stage doping) 168.4(60.17) -0.79(15.98) 9.55(7.83) 2.31(0.68) Experimental Example 16 NM9109+W 0.5mol% (doping before secondary heat treatment) 180.91(52.17) 1.37(13.76) 7.02(6.37) 1.93(0.65) Experimental Example 17 NCM950203+Nb 0.1mol%(doping before secondary heat treatment) 235.45(88.08) 4.335(21.57) 9.78(8.52) 2.21(0.77) Experimental Example 18 NCM950203+Nb 0.3mol%(doping before secondary heat treatment) 204.46(94.18) 0.16(22.73) 9.60(7.95) 2.24(0.62) Experimental Example 19 Zr 1.0 mol% - NCM950203 (Precursor preparation stage doping) 255.66(91.36) -0.22(14.58) 10.35(6.94) 2.03(0.81) Experiment Example 20 W 1.0 mol%-NCM950203 (precursor preparation stage doping) 154.20(30.09) 0.40(9.99) 3.60(3.43) 2.66(1.06) Experimental Example 21 CSNCM950203 (Concentration Gradient Type) 172.78(38.87) -2.45(17.83) 6.80(5.28) 2.03(0.81) Experiment Example 22 Sb 0.7mol%-NCM950203 (precursor preparation stage doping) 124.54(54.75) -2.23(11.69) 6.80(5.28) 2.24(0.90) Experiment Example 23 NCM950203 + Al 1.0 mol% (doping before 1st heat treatment) + Nb 0.5 mol% (doping before 2nd heat treatment) 250.49(92.14) 3.83(17.59) 8.83(7.65) 1.98(0.78) Experiment Example 24 NCM970201+Sb 0.7% (doping before secondary heat treatment) 149.28(60.70) 1.87(12.89) 6.82(5.73) 2.05(0.82) Experimental Example 25 LNO+Nb 0.5% (doping before secondary heat treatment) 242.35(105.43) -2.57(11.72) 7.32(6.55) 1.97(0.73) POSCO NCM90 385.75(172.89) 2.45(20.10) 15.03(8.25) 1.81(0.61) EASPRING Teck. NCM83 301.33(113.39) -3.11(15.24) 13.38(9.64) 1.75(0.71)

[0454] FIGS. 59 to 63 are SEM images and graphs for comparing the physical properties of primary particles on the surface of precursors used in the manufacture of cathode active materials according to comparative examples and experimental examples of the present invention.

[0455] Referring to FIG. 59, the precursor (NCM401248) used in the preparation of the cathode active material according to Comparative Example 3 and Experimental Example 5 was photographed with SEM, and the average size (a), average aspect ratio (b), and average orientation angle (c) of the primary particles on the surface of the precursor were measured.

[0456] Referring to FIG. 60, the precursor (NCM601822) used in the preparation of the cathode active material according to Comparative Example 6 and Experimental Example 8 was photographed with SEM, and the average size (a), average aspect ratio (b), and average orientation angle (c) of the primary particles on the surface of the precursor were measured.

[0457] Referring to Fig. 61, the precursor (Mo 1 mol%-NCM830710) used in the preparation of the cathode active material according to Comparative Example 9 and Experimental Example 11 was photographed with SEM, and the average size (a), average aspect ratio (b), and average orientation angle (c) of the primary particles on the surface of the precursor were measured.

[0458] Referring to Fig. 62, the precursor (NCM950203) used in the preparation of the cathode active material according to Comparative Example 1 and Experimental Examples 2-3 was photographed with SEM, and the average size (a), average aspect ratio (b), and average orientation angle (c) of the primary particles on the surface of the precursor were measured.

[0459] Referring to FIG. 63, the precursor (LNO) used in the preparation of the cathode active material according to Comparative Example 23 and Experimental Example 25 was photographed with SEM, and the average size (a), average aspect ratio (b), and average orientation angle (c) of the primary particles on the surface of the precursor were measured.

[0460] And, the results are summarized in [Table 66] below.

[0461] In summary, as can be seen in FIGS. 59 to 63 and Tables 1 to 60, Table 65, and Table 66, when a cathode active material according to the comparative and experimental examples is prepared using each precursor and applied to a half cell, it can be seen that the capacity retention rate and initial capacity of the half cell with the cathode active material according to the experimental examples are superior compared to the cathode active material according to the comparative examples. This factor is interpreted to be due to the fact that the orientation angle of the primary particles and the uniformity of particle size of the cathode active material according to the experimental examples are improved compared to the cathode active material according to the comparative examples, due to differences in the manufacturing process. Specifically, unlike the method of manufacturing the cathode active material according to the comparative examples, the method of manufacturing the cathode active material according to the experimental examples is interpreted as being due to the fact that the process of melting the lithium source in the mixture (precursor + lithium source) was performed sequentially (450°C or higher and 500°C or lower when the lithium source is LiOH, 700°C or higher and 750°C or lower when the lithium source is Li2CO3, 250°C or higher and 300°C or lower when the lithium source is LiNO3, and 10 minutes or more and 10 hours or less), the first heat treatment process (300°C or higher and 800°C or lower, 1 hour or more and 24 hours or less), and the cooling process (Quenching ~ 0.1°C / min cooling).

[0462] Precursor primary particles on the surface Average thickness (nm) (standard deviation) Average length (nm) (standard deviation) Average size (nm) (standard deviation) Mean orientation angle (°) (standard deviation) Mean aspect ratio (standard deviation) Mean absolute value orientation angle (°) (standard deviation) NCM401248 37.8(8.3) 1797.0(482) 257.3(46.5) 0.24(5.9) 49.4(16.0) 4.3(3.9) NCM601822 37.6(8.9) 1754.4(508) 252.4(45.8) 0.52(9.1) 49.4(18.4) 4.6(6.2) Mo 1mol%-NCM830710 32.4(7.1) 1620.0(444.5) 224.9(34.8) 1.8(4.6) 53.0(19.7) 4.0(2.9) NCM950203 30.7(10.3) 1408.2(430.7) 202.2(39.6) 0.9(4.3) 51.3(24.2) 3.6(2.4) LNO 30.5(9.6) 1473.7(508.2) 206.0(43.3) 1.3(4.5) 53.5(25.2) 3.8(2.7)

[0464] Although the present invention has been described in detail using preferred embodiments, the scope of the invention is not limited to specific embodiments and should be interpreted by the appended claims. Furthermore, those skilled in the art will understand that many modifications and variations are possible without departing from the scope of the invention. Explanation of the symbols

[0465] 1: Center (anode active material) 2: Core (anode active material) 3: Surface part (anode active material) 100: Cathode active material 101: Primary particles 110: Precursor 120: Lithium source 130: Mixture 140: Base cathode active material 151: First preliminary cathode active material 152: Second preliminary cathode active material R: Radius (positive active material)

Claims

Claim 1 A cathode active material comprising at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), wherein the region within 40% of the radius of the cathode active material starting from the center of the cathode active material is defined as the center, and wherein the Size Heterogeneity Index, which is an indicator quantitatively representing the size deviation of primary particles of the cathode active material in the center, is 0.26 or higher and 0.43 or lower. Claim 2 The cathode active material according to claim 1 further comprises a doping element, wherein the doping element comprises at least one of the following: the dopant is aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W). Claim 3 A positive electrode active material comprising at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), wherein the surface portion is defined as an area within 60% of the radius of the positive electrode active material starting from the surface of the positive electrode active material, and wherein the size heterogeneity index, which is an indicator quantitatively representing the size deviation of primary particles of the positive electrode active material in the surface portion, is 0.25 or higher and 0.45 or lower. Claim 4 A positive electrode active material according to claim 3, wherein the average size of the primary particles of the positive electrode active material on the surface portion is 400 nm or less, the average absolute orientation angle of the primary particles of the positive electrode active material on the surface portion is 17° or less, and the aspect ratio of the primary particles of the positive electrode active material on the surface portion is 6 or less. Claim 5 A positive electrode active material comprising at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), wherein the surface portion is defined as an area within 60% of the radius of the positive electrode active material starting from the surface of the positive electrode active material, and wherein the orientation heterogeneity index, which is an indicator quantitatively representing the deviation of the orientation angle of primary particles of the positive electrode active material in the surface portion, is 12.5° or less. Claim 6 A positive electrode active material according to claim 5, wherein the size heterogeneity index, which is an indicator quantitatively representing the size deviation of primary particles of the positive electrode active material on the surface portion, is 0.25 or higher and 0.45 or lower. Claim 7 A positive electrode active material comprising at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), wherein the surface portion is defined as an area within 60% of the radius of the positive electrode active material starting from the surface of the positive electrode active material, and wherein the grain boundary length density, which is an indicator quantitatively representing how densely grain boundaries are distributed within the particles of the positive electrode active material in the surface portion, is 5.576 or higher. Claim 8 A lithium secondary battery comprising: a positive electrode having a positive active material according to any one of claims 1, 3, 5, or 6; a negative electrode spaced apart from the positive electrode; and a solid electrolyte, a polymer electrolyte, or a liquid electrolyte provided between the positive electrode and the negative electrode. Claim 9 An oriented precursor used in the manufacture of an anode active material, comprising at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al), wherein a plurality of primary particles having a rod shape are arranged in a radiating form on a surface portion, wherein the average thickness of the primary particles on the surface portion is 100 nm or less, the average length of the primary particles on the surface portion is 2,000 nm or less, the average size of the primary particles on the surface portion is 300 nm or less, the average aspect ratio of the primary particles on the surface portion is 60 or less, and the average absolute orientation angle of the primary particles on the surface portion is 15° or less. Claim 10 A method for manufacturing an anode active material, comprising: a step of preparing a precursor containing a transition metal hydroxide; a step of mixing the precursor with a lithium source to produce a mixture; a step of melting the lithium source in the mixture to produce a base anode active material; a step of performing a first heat treatment on the base anode active material to produce a first preliminary anode active material; a step of cooling the first preliminary anode active material to produce a second preliminary anode active material; and a step of performing a second heat treatment on the cooled second preliminary anode active material to produce an anode active material. Claim 11 A method for manufacturing an anode active material according to claim 10, wherein the lithium melting temperature for melting the lithium source in the mixture is controlled according to the type of lithium source. Claim 12 A method for manufacturing an anode active material according to claim 11, wherein, when the lithium source is lithium hydroxide (LiOH), the lithium melting temperature is controlled to be 450°C or higher and 500°C or lower; when the lithium source is lithium carbonate (Li2CO3), the lithium melting temperature is controlled to be 700°C or higher and 750°C or lower; when the lithium source is lithium nitrate (LiNO3), the lithium melting temperature is controlled to be 250°C or higher and 300°C or lower; and when the lithium source is lithium acetate (LiCH3COO), the lithium melting temperature is controlled to be 250°C or higher and 300°C or lower. Claim 13 A method for manufacturing an anode active material according to claim 10, wherein, in the step of manufacturing the first pre-anode active material, the first heat treatment temperature of the base anode active material is controlled to be 300°C or higher and 800°C or lower, and in the step of manufacturing the second pre-anode active material, the cooling rate of the first pre-anode active material that has undergone the first heat treatment is controlled to be 0.1°C / min or higher. Claim 14 A method for manufacturing a positive electrode active material according to claim 10, wherein, in the step of manufacturing the positive electrode active material, the secondary heat treatment temperature of the second preliminary positive electrode active material is controlled to be 600°C or higher and 1,000°C or lower. Claim 15 A method for manufacturing a positive electrode active material according to claim 10, wherein at least one of the steps of preparing the precursor, preparing the mixture, or manufacturing the positive electrode active material comprises adding a dopant or not adding a dopant in any one of the steps. Claim 16 A method for manufacturing an anode active material according to claim 15, wherein the dopant comprises any one of aluminum (Al), boron (B), titanium (Ti), zirconium (Zr), vanadium (V), tin (Sn), chromium (Cr), tellurium (Te), hafnium (Hf), niobium (Nb), tantalum (Ta), antimony (Sb), molybdenum (Mo), or tungsten (W). Claim 17 A method for manufacturing an anode active material according to claim 10, wherein the precursor comprises at least one of nickel (Ni), manganese (Mn), cobalt (Co), or aluminum (Al). Claim 18 A method for manufacturing a cathode active material comprising the step of manufacturing a first preliminary cathode active material by first heat treating a base cathode active material in which a lithium source is dissolved within a mixture in which a precursor containing a transition metal hydroxide and a lithium source are mixed, wherein the lithium melting temperature for manufacturing the base cathode active material by melting lithium within the mixture is higher than the first heat treatment temperature depending on the type of lithium source, and wherein the capacity retention rate of a lithium secondary battery to which the cathode active material is applied is controlled according to the melting time in which the lithium source is melted at the lithium melting temperature. Claim 19 A method for manufacturing a positive electrode active material according to claim 18, wherein the lithium source is lithium hydroxide (LiOH), the lithium dissolution temperature is controlled to 450°C, and the capacity retention rate of the lithium secondary battery is improved as the melting time is controlled to 5 hours or more. Claim 20 A method for manufacturing a cathode active material comprising the step of manufacturing a second preliminary cathode active material by cooling a base cathode active material, wherein the lithium source is dissolved in a mixture of a precursor containing a transition metal hydroxide and a lithium source, and the first preliminary cathode active material is heat-treated, wherein the capacity retention rate of a lithium secondary battery to which the cathode active material is applied is controlled according to the cooling rate at which the first preliminary cathode active material is cooled. Claim 21 A method for manufacturing a positive electrode active material according to claim 20, wherein the cooling rate of the first preliminary positive electrode active material is controlled to be greater than 0.1℃ / min and less than 2.0℃ / min, thereby improving the capacity retention rate of the lithium secondary battery.

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