Positive electrode active material, positive electrode, and lithium secondary battery

Abstract

The present invention relates to a positive electrode active material, and more particularly to a positive electrode active material that can simultaneously solve the problems of conventional secondary particles and single particles, and which contains particles such as conventional single particles as primary particles and also contains secondary particles formed by the aggregation of multiple primary particles, thereby improving cell characteristics such as the lifespan of lithium secondary batteries and the amount of gas generated, as well as having excellent density characteristics and improving energy density, a positive electrode containing the same, and a lithium secondary battery.

Description

[Technical Field]

[0001] This application claims priority rights under Korean Patent Application No. 10-2023-0056231 dated April 28, 2023, and Korean Patent Application No. 10-2024-0057189 dated April 29, 2024, and all content disclosed in the documents of said Korean Patent Applications is incorporated herein by reference.

[0002] The present invention relates to a positive electrode active material, a positive electrode containing the same, and a lithium secondary battery. [Background technology]

[0003] In recent years, with the advancement of technologies such as electric vehicles, the demand for high-capacity secondary batteries has increased, leading to active research on high-nickel (High Ni) cathode active materials with superior capacity characteristics.

[0004] High-nickel positive electrode active materials, formed with a structure of secondary particles created by the aggregation of primary particles, undergo structural degeneration during the charging and discharging of lithium secondary batteries. However, relatively speaking, a significant change in the lattice structure constant, i.e., a change in volume within the unit cell, occurs. Such volume changes can cause cracks in the positive electrode active material. Furthermore, cracks may also occur in the positive electrode active material due to pressure during the rolling of the electrodes.

[0005] The cracks that occur in the high-nickel positive electrode active material in this way become more severe as the charging and discharging of the lithium secondary battery progresses. This can lead to the electrolyte failing to come into contact with the material or the material acting as a void that reduces conductivity, thus reducing the lifespan characteristics of the lithium secondary battery or increasing its resistance.

[0006] To minimize the occurrence of cracks in such secondary particle structures, attempts have been made to manufacture cathode active materials in single-particle form. However, such single-particle cathode active materials have the problem that the particle size is non-uniform, and the particle size distribution of the single-particle cathode active material obtained after grinding is large. In addition, single-particle cathode active materials have the problem that their specific surface area is small and their cell resistance characteristics are poor.

[0007] Therefore, there is a need to develop cathode active materials that can simultaneously solve the problems of both conventional secondary particles and single particles.

[0008] On the other hand, Korean Patent Registration No. 10-1785262 (Patent Document 1) discloses large-sized secondary particles that include aggregated primary particles, the secondary particles containing nickel-based lithium transition metal oxides, the average particle size of the primary particles being 3 to 5 μm, and the average particle size of the secondary particles being 10 to 20 μm. Such large-sized secondary particles, by including primary particles with an average particle size at the micron level, can improve rolling density and minimize cracks caused by rolling, and the specific surface area can be improved by the secondary particle structure, thereby improving cell properties.

[0009] To manufacture a positive electrode active material in the form of secondary particles, where the size of the primary particles is at the micron level, it is necessary to perform heat treatment at a higher temperature compared to secondary particles, where the size of the primary particles is at the submicron level (less than 1 μm), as disclosed in Patent Document 1. However, the higher the heat treatment temperature, the more the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure, causing a decrease in crystallinity, which in turn degrades the performance of the positive electrode active material. In particular, at high heat treatment temperatures, the degeneration of the layered structure of the lithium transition metal composite oxide into a rock salt structure becomes more severe when the nickel content in the lithium transition metal composite oxide constituting the positive electrode active material is high, as nickel is the most fragile component. Therefore, conventionally, as a positive electrode active material in the form of secondary particles with primary particle sizes at the micron level, only mid-nickel (Mid Ni) positive electrode active materials, in which the nickel content among the transition metals of the lithium transition metal composite oxide is at the 50 mol level, as described in Patent Document 1, were applicable. However, with high-nickel (High Ni) positive electrode active materials, which have a high nickel content among the transition metals of the lithium transition metal composite oxide and excellent capacitance characteristics, it was impossible to manufacture a positive electrode active material in the form of secondary particles with primary particle sizes at the micron level. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] KR10-1785262B1 [Patent Document 2] KR10-2017-0119573A [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] The problem that this invention aims to solve is to provide a positive electrode active material that can simultaneously solve the problems of both secondary particles and single particles in conventional high-nickel (High Ni) positive electrode active materials.

[0012] In other words, the present invention has been made to solve the problems of the above-mentioned prior art, and aims to provide a positive electrode active material that has a high nickel content among the transition metals of lithium transition metal composite oxide and has excellent capacity characteristics, and realizes a positive electrode active material in the form of secondary particles with a primary particle size at the micron level, thereby improving cell characteristics such as improved lifespan and reduced gas generation, as well as having excellent density characteristics and improving energy density.

[0013] Furthermore, the present invention aims to provide a positive electrode containing the positive electrode active material and a lithium secondary battery. [Means for solving the problem]

[0014] To solve the above problems, the present invention provides a positive electrode active material, a positive electrode containing the same, and a lithium secondary battery.

[0015] (1) The present invention includes secondary particles formed by the aggregation of a plurality of primary particles, wherein the plurality of primary particles have an average particle size of 1.5 μm or more and 5.0 μm or less as measured from an SEM image, and the particle size of the primary particles is the particle size based on the major axis of the primary particles, and in a frequency distribution graph in which the volume cumulative distribution measured using a laser diffraction particle size analyzer is shown with the x-axis representing the particle diameter as the x-value increases from left to right on a log scale, and the y-axis representing the volume distribution as the y-value increases from bottom to top, the peak point at the uppermost end of the y-axis of the peak appearing at the mode; and when a triangle is drawn using the two points of tangency of the frequency distribution curve that are tangent at the full width at half maximum (FWHM) of the mode, the interior angle (θ) at the left tangency of the two points of tangency of the frequency distribution curve that are tangent at the full width at half maximum L ) and the interior angle (θ) at the right-side point of tangency. R ) difference (θ L -θ R The present invention provides a positive electrode active material in which the ratio is between 6 and 20.

[0016] (2) The present invention relates to the ratio of the interior angle at the left contact point to the interior angle at the right contact point (θ L / θ RProvided is the positive electrode active material according to (1) above, wherein [[ID=]] is 1.100 or more and 2.000 or less.

[0017] (3) The present invention provides the positive electrode active material according to (1) or (2) above, wherein the frequency distribution graph is a unimodal distribution graph.

[0018] (4) The present invention provides the positive electrode active material according to any one of (1) to (3) above, which contains a lithium transition metal composite oxide containing nickel, cobalt, and manganese.

[0019] (5) The present invention provides the positive electrode active material according to any one of (1) to (4) above, which contains a lithium transition metal composite oxide containing 60 mol% or more of nickel among all transition metals.

[0020] (6) The present invention provides the positive electrode active material according to any one of (1) to (5) above, which contains a lithium transition metal composite oxide having an average composition represented by the following Chemical Formula 1.

[0021] [Chemical Formula 1] Li x Ni a Co b Mn c M 1 d O2

[0022] In Chemical Formula 1, M 1 is one or more selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, V, F, P, S, and Y, and 0.9 ≦ x ≦ 1.3, 0.6 ≦ a < 1.0, 0 < b < 0.4, 0 < c < 0.4, 0 ≦ d ≦ 0.2, and a + b + c + d = 1.

[0023] (7) The present invention provides the positive electrode active material according to any one of (1) to (6) above, wherein the plurality of primary particles contain single crystal primary particles.

[0024] (8) The present invention relates to the secondary particles, and the average particle size (D) is determined by the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 The present invention provides a positive electrode active material according to any one of (1) to (7) above, wherein the diameter is 7.0 μm or more and 20.0 μm or less.

[0025] (9) The present invention provides a positive electrode comprising a positive electrode active material described in any one of (1) to (8) above.

[0026] (10) The present invention provides a lithium secondary battery comprising the positive electrode described in (10) above, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. [Effects of the Invention]

[0027] The positive electrode active material of the present invention is a high-nickel (High Ni) positive electrode active material that can simultaneously solve the problems of both secondary particles and single particles in conventional materials. By realizing a positive electrode active material in the form of secondary particles with primary particle size at the micron level, it is possible to improve cell characteristics such as the lifespan of lithium secondary batteries and the amount of gas generated, as well as improve energy density by having excellent density characteristics. [Brief explanation of the drawing]

[0028] [Figure 1] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 1. [Figure 2] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 2. [Figure 3] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 3. [Figure 4] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 4. [Figure 5] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 5. [Figure 6](A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 6. [Figure 7] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 7. [Figure 8] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 8. [Figure 9] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 9. [Figure 10] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 10. [Figure 11] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Example 11. [Figure 12] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 1. [Figure 13] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 2. [Figure 14] (A) SEM image of the positive electrode active material, and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 3. [Figure 15] Comparative Example 4 shows (A) an SEM image of the positive electrode active material and (B) an SEM image of a cross-section of the positive electrode active material. [Figure 16] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 5. [Figure 17] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 6. [Figure 18] (A) SEM image of the positive electrode active material and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 7. [Figure 19] (A) SEM image of the positive electrode active material, and (B) SEM image of a cross-section of the positive electrode active material in Comparative Example 8. [Figure 20]This is a segmentation image showing multiple lithium composite transition metal oxides segmented by performing image analysis based on an artificial intelligence model on the SEM image of the positive electrode active material of Example 1. [Figure 21] This is a segmentation image showing multiple lithium composite transition metal oxides segmented by performing image analysis based on an artificial intelligence model on the SEM image of the positive electrode active material of Comparative Example 2. [Figure 22] This is a TEM image of the cross-section of the positive electrode active material in Example 1. [Figure 23] This is a TEM image of the cross-section of the positive electrode active material in Example 2. [Figure 24] This is a TEM image of the cross-section of the positive electrode active material in Example 8. [Figure 25] This is an EBSD pattern image of the cross-section of the positive electrode active material of Example 1. [Figure 26] This is an EBSD pattern image of the cross-section of the positive electrode active material in Example 2. [Figure 27] This is an EBSD pattern image of the cross-section of the positive electrode active material in Example 3. [Figure 28] This is an EBSD pattern image of the cross-section of the positive electrode active material in Example 4. [Figure 29] This is an EBSD pattern image of the cross-section of the positive electrode active material in Example 8. [Figure 30] This is an EBSD pattern image of the cross-section of the positive electrode active material in Example 10. [Figure 31] This is an EBSD pattern image of the cross-section of the positive electrode active material in Example 11. [Figure 32] This is an EBSD pattern image of the cross-section of the positive electrode active material of Comparative Example 5. [Figure 33] This is an EPMA analysis image of the positive electrode active material of Example 1. [Figure 34] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 1. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 35]This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 2. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 36] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 3. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 37] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 4. The x-axis represents the particle diameter, where the x-value increases from left to right, on a log scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 38] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 5. The x-axis represents the particle diameter, where the x-value increases from left to right, on a log scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 39] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 6. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 40] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 7. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 41] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 8. The x-axis represents the particle diameter, where the x-value increases from left to right, on a log scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 42] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 9. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 43] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 10. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 44] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 11. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 45] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Comparative Example 2. The x-axis represents the particle diameter, with the x-value increasing from left to right on a log scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 46] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Comparative Example 5. The x-axis represents the particle diameter, where the x-value increases from left to right, on a log scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 47] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Comparative Example 8. The x-axis represents the particle diameter, where the x-value increases from left to right, on a log scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 48] This frequency distribution graph shows the cumulative volume distribution measured for the positive electrode active material of Example 1 using a laser diffraction particle size analyzer. The x-axis represents the particle diameter, with the x-value increasing from left to right on a linear scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 49] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 2. The x-axis represents the particle diameter as the x-value increases from left to right on a linear scale, and the y-axis represents the volume distribution as the y-value increases from bottom to top. [Figure 50] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 3. The x-axis represents the particle diameter as the x-value increases from left to right on a linear scale, and the y-axis represents the volume distribution as the y-value increases from bottom to top. [Figure 51] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 4. The x-axis represents the particle diameter, with the x-value increasing from left to right on a linear scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 52] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 5. The x-axis represents the particle diameter as the x-value increases from left to right on a linear scale, and the y-axis represents the volume distribution as the y-value increases from bottom to top. [Figure 53] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 6. The x-axis represents the particle diameter, with the x-value increasing from left to right on a linear scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 54] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 7. The x-axis represents the particle diameter, with the x-value increasing from left to right on a linear scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 55]This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 8. The x-axis represents the particle diameter, with the x-value increasing from left to right on a linear scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 56] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 9. The x-axis represents the particle diameter as the x-value increases from left to right on a linear scale, and the y-axis represents the volume distribution as the y-value increases from bottom to top. [Figure 57] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 10. The x-axis represents the particle diameter as the x-value increases from left to right on a linear scale, and the y-axis represents the volume distribution as the y-value increases from bottom to top. [Figure 58] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Example 11. The x-axis represents the particle diameter, with the x-value increasing from left to right on a linear scale, and the y-axis represents the volume distribution, with the y-value increasing from bottom to top. [Figure 59] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Comparative Example 2. The x-axis represents the particle diameter, where the x-value increases from left to right, on a linear scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 60] This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Comparative Example 5. The x-axis represents the particle diameter, where the x-value increases from left to right, on a linear scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Figure 61]This frequency distribution graph shows the cumulative volume distribution measured using a laser diffraction particle size analyzer for the positive electrode active material of Comparative Example 8. The x-axis represents the particle diameter, where the x-value increases from left to right, on a log scale, and the y-axis represents the volume distribution, where the y-value increases from bottom to top. [Modes for carrying out the invention]

[0029] The present invention will be described in more detail below to facilitate understanding of it.

[0030] The terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may appropriately define the concepts of terms in order to best describe their invention.

[0031] In this invention, the term "primary particle" refers to the smallest particle unit that can be distinguished as a single mass when a cross-section of the positive electrode active material is observed using a scanning electron microscope (SEM), and consists of a single crystal or multiple crystal grains.

[0032] In this invention, the term "secondary particle" refers to a secondary structure formed by the aggregation of multiple primary particles. The average particle size of the secondary particle can be measured using a particle size analyzer.

[0033] In this invention, the term "average particle size (D 50 The average particle size is calculated by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size analyzer (for example, Microtrac's S3500), measuring the difference in diffraction patterns due to particle size as the particles pass through the laser beam to calculate the particle size distribution, and then calculating the particle diameter at the point where the cumulative volume distribution by particle size in the analyzer reaches 50%. 50 It can be measured.

[0034] In the present invention, the term "major axis of primary particle" refers to the length of the longest line segment when a line is drawn through two points on the boundary of the primary particle observed from the SEM image of the surface or cross-section of the secondary particle.

[0035] In the present invention, the term "minor axis of primary particle" refers to the length of the shortest line segment when a line is drawn through two points on the boundary of the primary particle observed from the SEM image of the surface or cross-section of the secondary particle.

[0036] positive electrode active material The present invention provides a positive electrode active material.

[0037] According to one embodiment of the present invention, the positive electrode active material of the present invention includes secondary particles in which a plurality of primary particles are aggregated, and the plurality of primary particles may have an average particle size measured from the SEM image of 1.5 μm or more and 5.0 μm or less.

[0038] According to one embodiment of the present invention, the secondary particles are secondary particles in which a plurality of primary particles are aggregated, and at least 2, and specifically, for example, at least 3 or more primary particles may be aggregated.

[0039] According to one embodiment of the present invention, the plurality of primary particles may have an average particle size measured from an SEM image of 1.5 μm or more, 1.6 μm or more, 1.7 μm or more, 1.8 μm or more, 1.9 μm or more, 2.0 μm or more, 2.1 μm or more, 2.2 μm or more, 2.3 μm or more, 2.4 μm or more, or 2.5 μm or more, and may also be 5.0 μm or less, 4.9 μm or less, The particle size may be 4.8 μm or less, 4.7 μm or less, 4.6 μm or less, 4.5 μm or less, 4.4 μm or less, 4.3 μm or less, 4.2 μm or less, 4.1 μm or less, 4.0 μm or less, 3.9 μm or less, 3.8 μm or less, 3.7 μm or less, 3.6 μm or less, 3.5 μm or less, 3.4 μm or less, 3.3 μm or less, 3.2 μm or less, 3.1 μm or less, or 3.0 μm or less. Here, when measuring the average particle size of the multiple primary particles from the SEM image, the particle size of each primary particle may be the particle size based on the major axis of the primary particle. If it is within this range, the rolling density of the positive electrode active material can be further improved, and the lifespan of the lithium secondary battery can be further improved.

[0040] According to one embodiment of the present invention, the positive electrode active material may include a lithium transition metal composite oxide containing nickel, cobalt, and manganese. Specifically, the positive electrode active material may include a lithium transition metal composite oxide containing 60 mol% or more of nickel among all transition metals. The lithium transition metal composite oxide may consist of primary particles, secondary particles, and the positive electrode active material itself containing these. Specifically, the positive electrode active material may include secondary particles formed by the aggregation of a plurality of primary particles made of the lithium transition metal composite oxide.

[0041] According to one embodiment of the present invention, the positive electrode active material may include a lithium transition metal composite oxide having an average composition represented by the following chemical formula 1.

[0042] [Chemical formula 1] Li x Ni a Co b Mn c M 1 d O2

[0043] In the above chemical formula 1, M 1 x is one or more elements selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, V, F, P, S, and Y, and 0.9≦x≦1.3, 0.6≦a<1.0, 0 <b<0.4、0<c<0.4、0≦d≦0.2、a+b+c+d=1である。

[0044] According to one embodiment of the present invention, in the chemical formula 1, x is the molar ratio of lithium to the transition metal in the lithium transition metal composite oxide, and may be 0.9 or more, 0.95 or more, or 1.0 or more, and may also be 1.1 or less, 1.07 or less, 1.05 or less, or 1.03 or less.

[0045] According to one embodiment of the present invention, in the chemical formula 1, a, b, c, and d are, respectively, nickel (Ni), cobalt (Co), manganese (Mn), and doped element (M 1 ) may be the mole fraction of ). For example, a above is the mole fraction of nickel (Ni) among the transition metals, and may be 0.6 or more, 0.7 or more, 0.8 or more, 0.85 or more, 0.88 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, 0.94 or more, 0.95 or more, or 0.96 or more, and may also be less than 1.0, 0.99 or less, 0.98 or less, 0.97 or less, or 0.96 or less. Also, b above is the mole fraction of cobalt (Co) among the transition metals, and may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more, and may also be less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. The above c is the mole fraction of manganese (Mn) among the transition metals, and may be greater than 0, 0.01 or more, or 0.05 or more, and may also be less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. The above d is the doped element (Mn) among the transition metals. 1) is a mole fraction that is 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, or 0.19 or more. Furthermore, the value may be less than 0.20, 0.19 or less, 0.18 or less, 0.17 or less, 0.16 or less, 0.15 or less, 0.14 or less, 0.13 or less, 0.12 or less, 0.11 or less, 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, or 0.01 or less. By adjusting the composition of the lithium transition metal composite oxide as described above, the capacity can be further improved.

[0046] According to one embodiment of the present invention, the plurality of primary particles may include single-crystal primary particles, in which case the rolling density of the positive electrode active material can be further improved. The single-crystal primary particles refer to primary particles made of a single crystal.

[0047] According to one embodiment of the present invention, the secondary particles are measured using a laser diffraction particle size analyzer, and the average particle size (D) is determined by the volume cumulative distribution. 50 The particle size may be 7.0 μm or more and 20.0 μm or less. As a specific example, the secondary particle may have an average particle size (D 50) 7.0 μm or larger, 7.1 μm or larger, 7.2 μm or larger, 7.3 μm or larger, 7.4 μm or larger, 7.5 μm or larger, 7.6 μm or larger, 7.7 μm or larger, 7.8 μm or larger, 7.9 μm or larger, 8.0 μm or larger, 8.1 μm or larger, 8.2 μm or larger, 8.3 μm or larger, 8.4 μm or larger, 8.5 μm or larger, 8.6 μm or larger, 8.7 μm or larger, 8.8 μm or larger, 8.9 μm or larger, Or it may be 9.0 μm or larger, and also 20.0 μm or less, 19.9 μm or less, 19.8 μm or less, 19.7 μm or less, 19.6 μm or less, 19.5 μm or less, 19.4 μm or less, 19.3 μm or less, 19.2 μm or less, 19.1 μm or less, 19.0 μm or less, 18.9 μm or less, 18.8 μm or less, 18.7 μm or less, 18.6 μm or less, 18.5 μm or less , 18.4 μm or less, 18.3 μm or less, 18.2 μm or less, 18.1 μm or less, 18.0 μm or less, 17.9 μm or less, 17.8 μm or less, 17.7 μm or less, 17.6 μm or less , 17.5μm or less, 17.4μm or less, 17.3μm or less, 17.2μm or less, 17.1μm or less, 17.0μm or less, 16.9μm or less, 16.8μm or less, 16.7μm or less The thickness may be 16.6 μm or less, 16.5 μm or less, 16.4 μm or less, 16.3 μm or less, 16.2 μm or less, 16.1 μm or less, 16.0 μm or less, 15.9 μm or less, 15.8 μm or less, 15.7 μm or less, 15.6 μm or less, 15.5 μm or less, 15.4 μm or less, 15.3 μm or less, 15.2 μm or less, 15.1 μm or less, or 15.0 μm or less. If it is within this range, the rolling density of the positive electrode active material can be further improved, and the lifespan can be further improved.

[0048] As a specific example, the positive electrode active material is a high-nickel positive electrode active material containing a lithium transition metal composite oxide in which nickel accounts for 60 mol% or more of the total transition metals, and the multiple primary particles are formed by the aggregation of multiple primary particles, which are like conventional single particles with a particle size of 0.5 μm or more and 5.0 μm or less, specifically micron-level primary particles of 1.0 μm or more, or more specifically, multiple primary particles with an average particle size of 2.0 μm or more and 3.5 μm or less as measured from SEM images, with an average particle size (D 50This may include large-particle secondary particles with a diameter of 7.0 μm or more and 20.0 μm or less, and can be described as a large-particle single-particle cluster in the sense that primary particles in single-particle form are aggregated to form large particles in secondary particle form.

[0049] As described in the background art of the present invention above, in order to manufacture a cathode active material in the form of secondary particles with primary particle sizes at the micron level, it is necessary to perform heat treatment at a higher temperature compared to secondary particles with primary particle sizes at the submicron level of less than 1 μm. However, the higher the heat treatment temperature, the more the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure, causing a decrease in crystallinity, which in turn degrades the performance of the cathode active material. In particular, the degeneration of the layered structure of the lithium transition metal composite oxide into a rock salt structure at high heat treatment temperatures becomes even more severe when the nickel content in the lithium transition metal composite oxide constituting the cathode active material is high, as nickel is the most fragile element. Therefore, conventionally, only mid-nickel cathode active materials, in which the nickel content among the transition metals of lithium transition metal composite oxides is at the 50 mol level, were applicable as cathode active materials in the form of secondary particles with primary particle sizes at the micron level. High-nickel cathode active materials, which have a high nickel content among the transition metals of lithium transition metal composite oxides and exhibit excellent capacitance characteristics, were incompatible with the production of cathode active materials in the form of secondary particles with primary particle sizes at the micron level.

[0050] However, the positive electrode active material of the present invention has a high nickel content among the transition metals in the lithium transition metal composite oxide, and even if the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure at high heat treatment temperatures, it recovers the rock salt structure back into a layered structure, thereby solving the above-mentioned problems. Specifically, unlike conventional mid-nickel positive electrode active materials, the positive electrode active material of the present invention is a high-nickel positive electrode active material containing a lithium transition metal composite oxide in which nickel accounts for 60 mol% or more of the total transition metals, and while it contains secondary particles with primary particle sizes at the micron level, it recovers the rock salt structure formed by high heat treatment temperatures back into a layered structure, and the lithium transition metal composite oxide exhibits excellent crystallinity, thus simultaneously solving the problems of both secondary particles and single particles in the conventional invention. The positive electrode active material of the present invention can be manufactured by recovering the rock salt structure formed by high heat treatment temperatures back into a layered structure as described above, and the method for recovering the rock salt structure back into a layered structure is not limited. According to one embodiment of the present invention, as a method for restoring the rock salt structure to a layered structure, a cobalt (Co) coating can be applied to a lithium transition metal composite oxide containing a rock salt structure formed by a high heat treatment temperature.

[0051] According to one embodiment of the present invention, the plurality of primary particles may include disk-shaped primary particles. Specifically, the plurality may include three or more disk-shaped primary particles, in which case the cell lifetime and energy density are excellent.

[0052] According to one embodiment of the present invention, the disc-shaped primary particle may mean a primary particle observed from an SEM image of the surface or cross-section of a secondary particle, in which, when two boundary lines of a primary particle located within an angle of 45° or less with respect to the major axis direction are drawn, and a virtual line is drawn across the two tangents, the ipsilateral interior angle is 150° or more and 210° or less, the minor axis of the primary particle is 0.3 μm or more, and the aspect ratio (major axis / minor axis) is 1.5 or more. As a specific example, the disc-shaped primary particle may have a minor axis of 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, or 1.0 μm or more. Here, if the minor axis of the disc-shaped primary particle is 0.3 μm or more and the aspect ratio (major axis / minor axis) is 1.5 or more, the proportion of the area of ​​the (003) plane among the crystal planes on the surface of the primary particle can be the largest.

[0053] According to one embodiment of the present invention, the disc-shaped primary particle may refer to a primary particle observed from an SEM image of the surface or cross-section of a secondary particle, in which, when two boundary lines of the primary particle located within an angle of 45° or less with respect to the major axis direction are drawn, and a single imaginary line is drawn crossing the two tangents, the ipsilateral interior angle is 150° or more and 210° or less, and the proportion of the area of ​​the (003) plane among the crystal planes on the surface of the primary particle is the largest. Here, when the proportion of the area of ​​the (003) plane among the crystal planes on the surface of the disc-shaped primary particle is the largest, the primary particle may have a minor axis of 0.3 μm or more and an aspect ratio (major axis / minor axis) of 1.5 or more. That is, the proportion of the area of ​​the (003) plane among the crystal planes on the surface of the primary particle is the largest can be confirmed by the fact that the minor axis of the primary particle is 0.3 μm or more and the aspect ratio (major axis / minor axis) is 1.5 or more.

[0054] As a specific example, the positive electrode active material includes secondary particles formed by the aggregation of multiple primary particles, the average particle size of the multiple primary particles measured from SEM images being 1.5 μm or more and 5.0 μm or less, the particle size of the primary particles being based on the major axis of the primary particles, the multiple primary particles including disk-shaped primary particles, the disk-shaped primary particles being such that, when a virtual tangent line with the most points of contact is drawn to two boundary lines of primary particles that exist within an angle of 45° or less relative to the major axis direction in the primary particles observed from SEM images of the surface or cross-section of the secondary particles, and a virtual line is drawn crossing the two tangent lines, the ipsilateral interior angle is 150° or more and 210° or less, and the proportion of the area of ​​the (003) plane among the crystal planes on the surface of the primary particles can be the largest.

[0055] According to one embodiment of the present invention, the positive electrode active material is shown in a frequency distribution graph in which the volume cumulative distribution measured using a laser diffraction particle size analyzer is shown with the x-axis representing the particle diameter as the x-value increases from left to right on a log scale, and the y-axis representing the volume distribution as the y-value increases from bottom to top. The triangle is formed by the peak point at the top of the y-axis of the peak appearing at the mode, and the two points of tangency of the frequency distribution curve that are tangent at the full width at half maximum (FWHM) of the mode, and the interior angle (θ) at the left tangency of the two tangency points of the frequency distribution curve that are tangent at the FWHM is the interior angle (θ) of the left tangency of the two tangency points of the frequency distribution curve that are tangent at the FWHM. L ) and the interior angle (θ) at the right-side point of tangency. R ) difference (θ L -θ R ) may be between 6 and 20. As a specific example, the interior angle (θ) at the left tangency. L ) and the interior angle (θ) at the right-side point of tangency. R ) difference (θ L -θ R ) may be 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 11 or more, 12 or more, 13 or more, or 14 or more, and may also be 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, or 15 or less. The positive electrode active material has a ratio (θ) of the interior angle at the left contact point to the interior angle at the right contact point. L / θ R) may be between 1.100 and 2.000. As a specific example, the ratio of the interior angle at the left tangency to the interior angle at the right tangency (θ) L / θ R ) are 1.100 or higher, 1.110 or higher, 1.120 or higher, 1.130 or higher, 1.140 or higher, 1.150 or higher, 1.160 or higher, 1.170 or higher, 1.180 or higher, 1.190 or higher, 1.200 or higher, 1.210 or higher, 1.220 or higher, 1.230 or higher, 1.240 or higher, 1.250 or higher, 1.260 or higher, 1.270 or higher, 1.280 or higher, 1.290 or higher, 1.300 or higher, 1.310 or higher, 1.320 or higher, 1.330 or higher, 1.340 or higher, 1.350 or higher, 1.360 The above values ​​may be 1.370 or higher, 1.380 or higher, 1.390 or higher, 1.400 or higher, 1.410 or higher, 1.420 or higher, 1.430 or higher, or 1.440 or higher, and may also be 1.450 or lower, 1.460 or lower, 1.470 or lower, 1.480 or lower, 1.490 or lower, 1.500 or lower, 1.550 or lower, 1.600 or lower, 1.650 or lower, 1.700 or lower, 1.750 or lower, 1.800 or lower, 1.850 or lower, 1.900 or lower, 1.950 or lower, or 2.000 or lower. Here, the frequency distribution graph may be a unimodal distribution graph.

[0056] According to one embodiment of the present invention, the positive electrode active material can exhibit positive skewness in a frequency distribution graph in which the volume cumulative distribution measured using a laser diffraction particle size analyzer is shown, with the x-axis representing the particle diameter increasing from left to right on a linear scale, and the y-axis representing the volume distribution increasing from bottom to top on a y-axis. Here, the frequency distribution graph may be a unimodal distribution graph.

[0057] According to one embodiment of the present invention, the positive electrode active material is the y-value (P) of the peak point at the uppermost end of the y-axis of the peak that appears in the mode of the volume cumulative distribution. MODE The ratio of the skewness value (S) to the skewness value (S / P MODE ) may be 0.037 or greater and 0.150 or less. As a specific example, the positive electrode active material is the y value (P) of the peak point at the uppermost end of the y axis of the peak that appears in the mode of the volume cumulative distribution.MODE ) The ratio (S / P) of the skewness value (S) to MODE ) may be 0.037 or more, 0.038 or more, 0.039 or more, 0.040 or more, 0.041 or more, 0.042 or more, 0.043 or more, 0.044 or more, 0.045 or more, 0.046 or more, 0.047 or more, 0.048 or more, 0.049 or more, 0.050 or more, 0.051 or more, 0.052 or more, 0.053 or more, 0.054 or more, 0.055 or more, 0.056 or more, 0.057 or more, 0.058 or more, 0.059 or more, 0.060 or more, 0.061 or more, 0.062 or more, 0.063 or more, 0.064 or more, 0.065 or more, 0.066 or more, 0.067 or more, 0.068 or more, 0.069 or more, 0.070 or more, 0.071 or more, 0.072 or more, 0.073 or more, 0.074 or more, 0.075 or more, 0.076 or more, 0.077 or more, 0.078 or more, 0.079 or more, 0.080 or more, 0.081 or more, 0.082 or more, 0.083 or more, 0.083 or more, 0.084 or more, 0.085 or more, 0.086 or more, 0.087 or more, 0.088 or more, 0.089 or more, 0.090 or more, 0.091 or more, 0.092 or more, 0.093 or more, 0.094 or more, 0.095 or more, 0.096 or more, 0.097 or more, 0.098 or more, 0.099 or more, or 0.100 or more, and may be 0.150 or less, 0.140 or less, 0.130 or less, 0.120 or less, or 0.110 or less. Here, the skewness value (S) can be calculated by the following formula 3.

[0058]

Number

[0059] According to one embodiment of the present invention, the positive electrode active material has a BET specific surface area measured by nitrogen adsorption BET specific surface area analysis of 0.20 m 2 / g or more and 0.35 m 2 / g or less. As a specific example, the positive electrode active material has a BET specific surface area measured by nitrogen adsorption BET specific surface area analysis of 0.20 m 2 / g or more and 0.21 m 2 / g or more and 0.22 m 2 / g or more, 0.23m 2 / g or more, 0.24m 2 / g or more, 0.25m 2 / g or more, 0.26m 2 / g or more, 0.27m 2 / g or more, 0.28m 2 / g or more, 0.29m 2 / g or more, 0.30m 2 / g or more, or 0.31m 2 It may be 0.35m or more, and also 0.35m 2 Less than / g, or 0.34m 2 It may be less than or equal to / g. Within this range, DC resistance decreases and rolling density can be improved.

[0060] According to one embodiment of the present invention, the positive electrode active material has an average particle size (D) determined by the volume cumulative distribution measured with a laser diffraction particle size analyzer for the secondary particles. 50 The size of the secondary particle cross-section is 7.0 μm or larger and 20.0 μm or smaller, and the size of the secondary particle cross-section observed from the SEM image of the secondary particle cross-section is equal to the average particle size (D) of the secondary particle. 50 In the cross-section of a secondary particle having a size within the specified range, the number of primary particle cross-sections observed within a unit area of ​​5 μm x 5 μm within the cross-section of the secondary particle may be one or more and 100 or less.

[0061] According to one embodiment of the present invention, the size of the cross-section of the secondary particle observed from the SEM image of the cross-section of the secondary particle is the average particle size (D 50 In the cross-section of a secondary particle having a size within the specified range, the number of primary particle cross-sections observed within a unit area of ​​5 μm x 5 μm within the cross-section of the secondary particle means the number of primary particle cross-sections that include all of the primary particle cross-sections observed within the unit area, as well as the number of primary particle cross-sections that include at least a part of the primary particle cross-section. Furthermore, the unit area of ​​5 μm x 5 μm within the cross-section of the secondary particle is the unit area at any point within the cross-section of the secondary particle, and its position is not restricted as long as it is within the cross-section of the secondary particle.

[0062] According to one embodiment of the present invention, the positive electrode active material is such that the size of the cross-section of the secondary particles, as observed from the SEM image of the cross-section of the secondary particles, is equal to the average particle size (D) of the secondary particles. 50 In the cross-section of a secondary particle having a size within the range, the number of primary particle cross-sections observed within a unit area of ​​5 μm x 5 μm in the cross-section of the secondary particle may be 1 or more and 100 or less. For example, it may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or 10 or more. It may also be 100 or less, 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, or 25 or less. If such a range is met, the positive electrode active material is formed by the aggregation of multiple primary particles, which are primary particles with a particle size of 0.5 μm or more and 5.0 μm or less, like conventional single particles, specifically micron-level primary particles of 1.0 μm or more, or more specifically, multiple primary particles with an average particle size of 2.0 μm or more and 3.5 μm or less, as measured from SEM images, with an average particle size (D 50 This indicates that the product contains large-particle secondary particles with a diameter of 7.0 μm or more and 20.0 μm or less.

[0063] According to one embodiment of the present invention, the positive electrode active material has an average particle size (D) determined by the volume cumulative distribution measured with a laser diffraction particle size analyzer for the secondary particles. 50 The size of the secondary particle cross-section is 7.0 μm or larger and 20.0 μm or smaller, and the size of the secondary particle cross-section is observed from the backscattered electron diffraction (EBSD) pattern of the SEM image of the secondary particle cross-section (measured under the conditions of acceleration voltage 20 kV, WD 16 mm, measurement magnification 5,000x (width 16 μm × height 16 μm), step size 0.025 μm), and the average particle size of the secondary particle (D 50 In the cross-section of a secondary particle having a size within the specified range, the number of grain cross-sections observed within a unit area of ​​5 μm x 5 μm in the cross-section of the secondary particle may be one or more and 150 or less.

[0064] According to one embodiment of the present invention, the size of the cross-section of a secondary particle is observed from the backscatter electron diffraction (EBSD) pattern of a SEM image of the cross-section of a secondary particle (measured under the conditions of acceleration voltage 20kV, WD 16mm, measurement magnification 5,000x (width 16μm × height 16μm), step size 0.025μm), and the average particle size (D) of the secondary particle. 50 In the cross-section of a secondary particle having a size within the specified range, the number of grain cross-sections observed within a unit area of ​​5 μm x 5 μm within the cross-section of the secondary particle means the number of grain cross-sections that include all grain cross-sections, as well as all grain cross-sections that include at least a part of the grain cross-section. Furthermore, the unit area of ​​5 μm x 5 μm within the cross-section of the secondary particle is the unit area at any point within the cross-section of the secondary particle, and its position is not restricted as long as it is within the cross-section of the secondary particle.

[0065] According to one embodiment of the present invention, the positive electrode active material is such that the size of the cross-section of the secondary particles is observed from the backscatter electron diffraction (EBSD) pattern of the cross-section of the secondary particles (measured under the conditions of acceleration voltage 20kV, WD 16mm, measurement magnification 5,000x (width 16μm × height 16μm), step size 0.025μm), and the size of the cross-section of the secondary particles is the average particle size (D 50In the cross-section of a secondary particle having a size within the range, the number of grain cross-sections observed within a unit area of ​​5 μm x 5 μm in the cross-section of the secondary particle may be 1 or more and 150 or less. Specific examples include 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, or 9 or more. Alternatively, it may be 150 or less, 145 or less, 140 or less, 135 or less, 130 or less, 125 or less, 120 or less, 115 or less, 110 or less, 105 or less, 100 or less, 95 or less, 90 or less, 85 or less, 80 or less, 75 or less, 70 or less, 65 or less, 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, 35 or less, 30 or less, 25 or less, or 20 or less. If such a range is met, the positive electrode active material is formed by the aggregation of multiple primary particles, which are primary particles with a particle size of 0.5 μm or more and 5.0 μm or less, like conventional single particles, specifically micron-level primary particles of 1.0 μm or more, or more specifically, multiple primary particles with an average particle size of 2.0 μm or more and 3.5 μm or less, as measured from SEM images, with an average particle size (D 50 This indicates that the product contains large-particle secondary particles with a diameter of 7.0 μm or more and 20.0 μm or less.

[0066] According to one embodiment of the present invention, the positive electrode active material has a single crystallinity of 0.15 μm, calculated by the following formula 1. 3 That's all.

[0067]

number

[0068] In equation 1 above, radius(grain) is the size of the cross-section of the secondary particle observed from the backscattered electron diffraction (EBSD) pattern of the cross-section of the secondary particle (measured under the conditions of acceleration voltage 20kV, WD 16mm, measurement magnification 5,000x (width 16μm × height 16μm), step size 0.025μm), where the average particle size (D) of the secondary particle is the size of the cross-section of the secondary particle. 50Of all the cross-sections of grains observable in the cross-section of secondary particles having a size within the range, the radius of the cross-section of the grain when assuming that the cross-section of the grain is circular, where the cross-sectional area of the grain is 0.196 μm 2 or more, and n is the number of grains.

[0069] According to one embodiment of the present invention, the positive electrode active material has a crystallinity of 0.15 μm calculated by the formula 1 3 or more and 12.70 μm 3 or less. As a specific example, the positive electrode active material has a crystallinity of 0.15 μm calculated by the formula 1 3 or more and 0.20 μm 3 or more and 0.25 μm 3 or more and 0.30 μm 3 or more and 0.35 μm 3 or more and 0.40 μm 3 or more and 0.45 μm 3 or more and 0.50 μm 3 or more and 0.55 μm 3 or more and 0.60 μm 3 or more and 0.65 μm 3 or more and 0.70 μm 3 or more and 0.75 μm 3 or more and 0.80 μm 3 or more and 0.85 μm 3 or more and 0.90 μm 3 or more and 0.95 μm 3 or more and 1.00 μm 3 or more and 1.05 μm 3 or more, and the upper limit is not particularly limited, but 20.00 μm 3 or less, 19.00 μm 3 or less, 18.00 μm 3 or less, 17.00 μm 3 or less, 16.00 μm 3 or less, 15.00 μm 3 or less, 14.00 μm 3 or less, 13.00 μm 3 or less, or 12.70 μm 3 or less.

[0070] According to one embodiment of the present invention, the positive electrode active material may include a lithium transition metal composite oxide containing aluminum (Al), yttrium (Y), and zirconium (Zr). Specifically, the positive electrode active material may contain aluminum (Al), yttrium (Y), and zirconium (Zr) as doping elements.

[0071] According to one embodiment of the present invention, the aluminum (Al) may be present in a content of 500 ppm to 3,000 ppm relative to the total weight of the lithium transition metal composite oxide. Specifically, the aluminum (Al) may be present in a content of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more relative to the total weight of the lithium transition metal composite oxide, and may also be present in a content of 3,000 ppm or less, 2,500 ppm or less, or 2,000 ppm or less.

[0072] According to one embodiment of the present invention, the yttrium (Y) may be present in a content of 100 ppm to 2,000 ppm relative to the total weight of the lithium transition metal composite oxide. Specifically, the yttrium (Y) may be present in a content of 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, or 500 ppm or more relative to the total weight of the lithium transition metal composite oxide, and may also be present in a content of 2,000 ppm or less, 1,900 ppm or less, 1,800 ppm or less, 1,700 ppm or less, 1,600 ppm or less, or 1,500 ppm or less.

[0073] According to one embodiment of the present invention, the zirconium (Zr) may be present in an amount of 500 ppm to 5,000 ppm relative to the total weight of the lithium transition metal composite oxide. Specifically, the zirconium (Zr) may be present in an amount of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more relative to the total weight of the lithium transition metal composite oxide, and may also be present in an amount of 5,000 ppm or less, 4,500 ppm or less, 4,000 ppm or less, 3,500 ppm or less, or 3,000 ppm or less relative to the total weight of the lithium transition metal composite oxide.

[0074] According to one embodiment of the present invention, the positive electrode active material may include a lithium transition metal composite oxide having an average composition represented by the following chemical formula 2.

[0075] [Chemical formula 2] Li x [Ni a Co b Mn c Al e Y f Zr g M 2 d ]O 2-y A y

[0076] In the above chemical formula 2, M 2 a is one or more elements selected from the group consisting of B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, V, F, P, and S, and A is one or more elements selected from the group consisting of F, Cl, Br, I, and S, with 0.9≦x≦1.3, 0.6≦a<1.0, 0 <b<0.4、0<c<0.4、0≦d≦0.2、0<e≦0.01、0<f≦0.0006、0<g≦0.0005、a+b+c+d+e+f+g=1、0≦y≦0.2である。

[0077] According to one embodiment of the present invention, in the chemical formula 2, x is the molar ratio of lithium to the transition metal in the lithium transition metal composite oxide, and may be 0.9 or more, 0.95 or more, or 1.0 or more, and may also be 1.1 or less, 1.07 or less, 1.05 or less, or 1.03 or less.

[0078] According to one embodiment of the present invention, in the chemical formula 2, a, b, c, d, e, f, and g are, respectively, nickel (Ni), cobalt (Co), manganese (Mn), and doped element (M 2), aluminum (Al), yttrium (Y), and zirconium (Zr) may be mole fractions. As a specific example, a is the mole fraction of nickel (Ni) among the transition metals, which may be 0.6 or more, 0.7 or more, 0.8 or more, 0.85 or more, 0.88 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, 0.94 or more, 0.95 or more, or 0.96 or more, and may also be less than 1.0, 0.99 or less, 0.98 or less, 0.97 or less, or 0.96 or less. Furthermore, b is the mole fraction of cobalt (Co) among the transition metals, which may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more, and may also be less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. c is the mole fraction of manganese (Mn) among the transition metals, which may be greater than 0, 0.01 or more, or 0.05 or more, and may also be less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. d is the mole fraction of doped elements (Mn) among the transition metals. 2) is a mole fraction that is 0, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, 0.05 or more, 0.06 or more, 0.07 or more, 0.08 or more, 0.09 or more, 0.10 or more, 0.11 or more, 0.12 or more, 0.13 or more, 0.14 or more, 0.15 or more, 0.16 or more, 0.17 or more, 0.18 or more, or 0.19 or more. Furthermore, it may be less than 0.20, 0.19 or less, 0.18 or less, 0.17 or less, 0.16 or less, 0.15 or less, 0.14 or less, 0.13 or less, 0.12 or less, 0.11 or less, 0.10 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, or 0.01 or less. The aforementioned e is the mole fraction of aluminum (Al) among the transition metals, and may be greater than 0, 0.001 or more, 0.002 or more, 0.003 or more, 0.004 or more, or 0.005 or more, and may also be 0.01 or less, 0.009 or less, or 0.008 or less. The aforementioned f is the mole fraction of yttrium (Y) among the transition metals, and may be greater than 0, 0.0001 or more, 0.0002 or more, or 0.0003 or more, and may be 0.0006 or less, 0.0005 or less, or 0.0004 or less. The aforementioned g is the mole fraction of zirconium (Zr) among the transition metals, and may be greater than 0, 0.0001 or more, or 0.0002 or more, and may be 0.0005 or less, or 0.0004 or less.

[0079] According to one embodiment of the present invention, in the chemical formula 2, y is the molar ratio of element A in which oxygen is substituted in the lithium transition metal composite oxide, and may be 0, greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more, and may also be 0.2 or less, 0.15 or less, or 0.1 or less.

[0080] According to one embodiment of the present invention, the positive electrode active material is aluminum (Al), zirconium (Zr), and M 3 The positive electrode active material may include a lithium transition metal composite oxide containing aluminum (Al), zirconium (Zr), and M. 3 It may contain as a doping element.

[0081] According to one embodiment of the present invention, the M 3 This may be a metallic element with an oxidation state of +4 or higher. As a specific example, the above M 3 This may be one or more elements selected from the group consisting of titanium (Ti), tantalum (Ta), tungsten (W), vanadium (V), molybdenum (Mo), and niobium (Nb).

[0082] According to one embodiment of the present invention, the aluminum (Al) may be present in a content of 500 ppm to 3,000 ppm relative to the total weight of the lithium transition metal composite oxide. Specifically, the aluminum (Al) may be present in a content of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more relative to the total weight of the lithium transition metal composite oxide, and may also be present in a content of 3,000 ppm or less, 2,500 ppm or less, or 2,000 ppm or less.

[0083] According to one embodiment of the present invention, the zirconium (Zr) may be present in an amount of 500 ppm to 3,000 ppm relative to the total weight of the lithium transition metal composite oxide. Specifically, the zirconium (Zr) may be present in an amount of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more relative to the total weight of the lithium transition metal composite oxide, and may also be present in an amount of 3,000 ppm or less, 2,500 ppm or less, or 2,000 ppm or less.

[0084] According to one embodiment of the present invention, the M 3 It may be present in an amount of 100 ppm to 2,000 ppm relative to the total weight of the lithium transition metal composite oxide. As a specific example, the M 3It may be included in a content of 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, or 500 ppm or more relative to the total weight of the lithium transition metal composite oxide, and may also be included in a content of 2,000 ppm or less, 1,900 ppm or less, 1,800 ppm or less, 1,700 ppm or less, 1,600 ppm or less, or 1,500 ppm or less.

[0085] According to one embodiment of the present invention, the positive electrode active material includes a coating portion formed on at least one of the surfaces of primary particles, the interfaces of primary particles, and the surfaces of secondary particles, and the coating portion may include one or more coating elements selected from the group consisting of cobalt (Co) and boron (B).

[0086] According to one embodiment of the present invention, the coating portion may be an island-shaped coating portion formed on at least one part of the surface of a primary particle, the interface of a primary particle, and the surface of a secondary particle.

[0087] According to one embodiment of the present invention, the coating portion may be a coating layer formed surrounding at least one of the surface of a primary particle, the interface of a primary particle, and the surface of a secondary particle.

[0088] According to one embodiment of the present invention, the coating portion may include at least one coating portion containing cobalt (Co), a coating portion containing cobalt (Co) and boron (B), and a coating portion containing boron (B).

[0089] According to one embodiment of the present invention, the coating portion may include a coating portion in which a coating portion containing cobalt (Co), a coating portion containing cobalt (Co) and boron (B), and a coating portion containing boron (B) are formed in that order.

[0090] According to one embodiment of the present invention, the coating portion may contain cobalt-boron oxide.

[0091] According to one embodiment of the present invention, when the positive electrode active material is placed in a cylindrical mold with a diameter of 13 mm using an automatic pellet press and a force equivalent to 9,000 kgf is applied to form pellets, the rolling density calculated by the following formula 2 is 3.60 g / cm³. 3 That's all.

[0092] [Formula 2] Rolling density (g / cm³) 3 ) = Weight of positive electrode active material (g) / Volume of pellet (cm³) 3 )

[0093] According to one embodiment of the present invention, the positive electrode active material has a rolling density of 3.60 g / cm³ calculated by formula 2. 3 The above is sufficient, and as a specific example, 3.61 g / cm³ 3 More than 3.62g / cm 3 More than 3.63g / cm 3 More than 3.64g / cm 3 More than 3.65g / cm 3 More than 3.66g / cm 3 More than 3.67g / cm 3 Above, 3.68g / cm 3 More than 3.69g / cm 3 More than 3.70g / cm 3 Above, or 3.71 g / cm³ 3 The above is sufficient, and there is no particular upper limit, but 10.0 g / cm³ 3 The following is acceptable:

[0094] According to one embodiment of the present invention, the positive electrode active material is used to confirm the discharge capacity based on the output characteristics of the positive electrode active material, and the components other than the positive electrode active material are not particularly limited as long as they can be used in a lithium secondary battery. The positive electrode active material is used to confirm the discharge capacity based on the output characteristics of the positive electrode active material, and the components other than the positive electrode active material are not particularly limited as long as they can be used in a lithium secondary battery. As a specific example, the positive electrode active material may have a discharge capacity of 92.0% or more, 92.1% or more, 92.2% or more, 92.3% or more, 92.4% or more, 92.5% or more, 92.6% or more, 92.7% or more, 92.8% or more, 92.9% or more, 93.0% or more, or 93.1% or more, based on the discharge capacity when the lithium secondary battery is charged with a current of 0.5C and then discharged with a current of 0.1C, and there is no particular upper limit, but it may be 100% or less.

[0095] According to one embodiment of the present invention, the positive electrode active material is used to confirm the discharge capacity based on the output characteristics of the positive electrode active material, and the components other than the positive electrode active material are not particularly limited as long as they can be used in a lithium secondary battery. The positive electrode active material is used to confirm the discharge capacity based on the output characteristics of the positive electrode active material, and the components other than the positive electrode active material are not particularly limited as long as they can be used in a lithium secondary battery. As a specific example, the positive electrode active material may have a discharge capacity of 89.0% or more, 89.1% or more, 89.2% or more, 89.3% or more, 89.4% or more, 89.5% or more, 89.6% or more, 89.7% or more, 89.8% or more, 89.9% or more, 90.0% or more, 90.1% or more, 90.2% or more, 90.3% or more, or 90.4% or more, with no particular upper limit, but it may be 100% or less.

[0096] According to one embodiment of the present invention, the positive electrode active material is such that when the volume value is calculated for each primary particle observed from an SEM image (measurement magnification 3,000x) of the surface of the secondary particles using the following formula 5, the degree of single-particle formation (Dv) corresponds to the diameter of the volume at the point where the cumulative volume distribution of the primary particles reaches 50%. 50 The diameter may be between 1.2 μm and 3.8 μm.

[0097]

number

[0098] In the above formula 5, The radius is the radius of the primary particle's surface, assuming that the primary particle's surface is circular, as observed from the SEM image of the secondary particle's surface (measurement magnification 3,000x).

[0099] As a specific example, the positive electrode active material is the degree of single-particle formation (Dv 50 The diameter may be 1.2 μm or larger, 1.3 μm or larger, 1.4 μm or larger, 1.5 μm or larger, 1.6 μm or larger, or 1.65 μm or larger, and may also be 3.8 μm or smaller, 3.7 μm or smaller, 3.6 μm or smaller, 3.59 μm or smaller, 3.58 μm or smaller, 3.57 μm or smaller, 3.56 μm or smaller, or 3.55 μm or smaller.

[0100] Method for manufacturing positive electrode active material This invention provides a method for producing a positive electrode active material.

[0101] According to one embodiment of the present invention, the method for producing the positive electrode active material may be a method for producing the above-mentioned positive electrode active material.

[0102] According to one embodiment of the present invention, the method for producing the positive electrode active material may include the step (S10) of mixing a positive electrode active material precursor containing nickel, cobalt, and manganese with a lithium raw material and performing calcination to produce a calcined product.

[0103] According to one embodiment of the present invention, step (S10) may be carried out by methods such as a method in which firing is performed by dividing the temperature interval within one firing step (one-step method), a method in which firing is performed by dividing it into two firing steps (two-step method), and a method in which pre-firing is performed before firing is performed by dividing the temperature interval within one firing step (pre-firing method).

[0104] According to one embodiment of the present invention, the one-step method is a method of performing firing in two consecutive temperature intervals within a single firing step, wherein a mixture of positive electrode active material precursor and lithium raw material is subjected to one stage of firing, followed by a second stage of firing by changing the temperature interval. In this case, the second stage of firing may be performed at a lower temperature than the first stage of firing, and the firing temperature of each stage may be adjusted according to the nickel content. By adjusting the temperature in this way, the morphology and size of the primary particles and the average particle size of the secondary particles can be adjusted.

[0105] According to one embodiment of the present invention, the two-step method is a method in which primary and secondary calcination are performed separately. Primary calcination may be performed on a mixture of a positive electrode active material precursor and a lithium raw material, the first calcined product produced by the primary calcination may be pulverized, and then the pulverized product may be subjected to secondary calcination. In this case, the secondary calcination may be performed at a lower temperature than the primary calcination, and the calcination temperature of each can be adjusted according to the nickel content. By adjusting the temperature in this way, the morphology and size of the primary particles and the average particle size of the secondary particles can be adjusted.

[0106] According to one embodiment of the present invention, the calcination method is a method of performing calcination before the first step of firing, and the calcination may be performed on a mixture of the positive electrode active material precursor and the lithium raw material, and the first step method may be performed on the calcined product. In this case, the calcination may be performed at a lower temperature than the first step of firing, and the firing temperature can be adjusted according to the nickel content. By adjusting the temperature in this way, the morphology and size of the primary particles and the average particle size of the secondary particles can be adjusted.

[0107] According to one embodiment of the present invention, the positive electrode active material precursor may contain 60 mol% or more of nickel among the transition metals. Specifically, the positive electrode active material precursor may be a transition metal hydroxide containing nickel, cobalt, and manganese, and containing 60 mol% or more of nickel among the transition metals. Specifically, the transition metal hydroxide may have an average composition represented by the following chemical formula 3.

[0108] [Chemical formula 3] Ni a’ Co b’ Mn c’ (OH)2

[0109] In the above chemical formula 3, 0.6 ≤ a' < 1.0, 0 <b’<0.4、0<c’<0.4、a’+b’+c’=1である。

[0110] According to one embodiment of the present invention, in the chemical formula 3, a', b', and c' may be the mole fractions of nickel (Ni), cobalt (Co), and manganese (Mn), respectively, among the transition metals. As a specific example, a' may be the mole fraction of nickel (Ni) among the transition metals, and may be 0.6 or more, 0.7 or more, 0.8 or more, 0.85 or more, 0.88 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, 0.94 or more, 0.95 or more, or 0.96 or more, and may also be less than 1.0, 0.99 or less, 0.98 or less, 0.97 or less, or 0.96 or less. Furthermore, b' is the mole fraction of cobalt (Co) among the transition metals, and may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more, and may also be less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less. c' is the mole fraction of manganese (Mn) among the transition metals, and may be greater than 0, 0.01 or more, or 0.05 or more, and may also be less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less.

[0111] According to one embodiment of the present invention, the lithium raw material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, for example, Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, Li3C6H5O7, or a mixture thereof.

[0112] According to one embodiment of the present invention, step (S10) may further include one or more doping raw materials selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, F, P, S, and Y. The doping raw materials may be acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, or oxyhydroxides containing the elements, and specific examples may be Al2O3, Al(OH)3, Al(NO3)3·9H2O, Al2(SO4)3, Y2O3, ZrO2, etc.

[0113] According to one embodiment of the present invention, the doping material may contain Al, Y, and Zr. Furthermore, the doping material may contain Al, Zr, and a metal element (M) with an oxidation state of +4 or higher. 3 ) may be included.

[0114] According to one embodiment of the present invention, in step (S10), when the positive electrode active material precursor and the lithium raw material are mixed, the molar ratio (Li / M) of lithium (Li) in the lithium raw material to the transition metal (M) in the positive electrode active material precursor may be 0.9 or more and 1.3 or less. Specifically, the Li / M may be 0.9 or more, 0.95 or more, or 1.0 or more, and may also be 1.1 or less, 1.07 or less, 1.05 or less, or 1.04 or less. The Li / M can be adjusted by the nickel content in the transition metal.

[0115] According to one embodiment of the present invention, the method for producing the positive electrode active material may further include a step (S20) of coating the positive electrode active material produced in step (S10). Specifically, step (S20) may include one or more coating raw materials selected from the group consisting of Co and B. Alternatively, step (S20) may further include an Al coating raw material.

[0116] According to one embodiment of the present invention, the coating in step (S20) may be carried out by coating each coating raw material simultaneously, or by coating them sequentially. As a specific example, the coating in step (S20) may include the steps of mixing the Co coating raw material and the Al coating raw material with the positive electrode active material and heat-treating it (S21), and mixing the B coating raw material with the coated product produced in step (S21) and heat-treating it (S22).

[0117] According to one embodiment of the present invention, the Co coating raw material may be a cobalt hydroxide such as Co(OH)2, the Al coating raw material may be an aluminum hydroxide such as Al(OH)3, and the B coating raw material may be H3BO3.

[0118] According to one embodiment of the present invention, the method for producing the positive electrode active material may include, when performing steps (S10) and (S20), a step of crushing the fired product after firing, if necessary. The crushing may be carried out using any crushing apparatus capable of crushing the positive electrode active material, without any particular limitations.

[0119] According to one embodiment of the present invention, the doping raw material and the coating raw material may be added in an adjusted manner to satisfy the content of the doping element and the coating element of the positive electrode active material described above.

[0120] positive electrode The present invention provides a positive electrode containing the positive electrode active material.

[0121] According to one embodiment of the present invention, the positive electrode includes a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and the positive electrode active material layer may include the positive electrode active material.

[0122] According to one embodiment of the present invention, the positive electrode current collector may contain a highly conductive metal and is not particularly limited as long as the positive electrode active material layer adheres to it easily and it is unreactive within the battery voltage range. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treatment using carbon, nickel, titanium, silver, etc. The positive electrode current collector usually has a thickness of 3 μm to 500 μm, and the adhesion strength of the positive electrode active material may be increased by forming fine irregularities on the surface of the current collector. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0123] According to one embodiment of the present invention, the positive electrode active material layer may optionally contain a conductive material and a binder along with the positive electrode active material. In this case, the positive electrode active material may be present in an amount of 80% to 99% by weight, more specifically 85% to 98.5% by weight, relative to the total weight of the positive electrode active material layer. When within this range, excellent capacitance characteristics can be observed.

[0124] According to one embodiment of the present invention, the conductive material is used to impart conductivity to the electrode and can be used in the constructed battery without particular limitations, as long as it does not cause a chemical change and has electronic conductivity. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive tubes such as carbon nanotubes; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these may be used alone or as a mixture of two or more. The conductive material may be included in an amount of 0.1% to 15% by weight relative to the total weight of the positive electrode active material layer.

[0125] According to one embodiment of the present invention, the binder plays a role in improving the adhesion between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and polymers in which the hydrogen atoms of these materials are substituted with Li, Na, or Ca, or various copolymers thereof, of which one or more can be used individually or in mixtures of two or more. The binder may be present in an amount of 0.1% to 15% by weight relative to the total weight of the positive electrode active material layer.

[0126] According to one embodiment of the present invention, the positive electrode may be manufactured by a conventional method for manufacturing a positive electrode, except that the positive electrode active material described above is used. Specifically, the positive electrode may be manufactured by coating a positive electrode active material layer-forming composition, which is prepared by dissolving or dispersing the positive electrode active material and, if necessary, a binder, a conductive material, and a dispersant in a solvent, onto a positive electrode current collector, followed by drying and rolling. Alternatively, the positive electrode active material layer-forming composition may be cast onto another support, and the resulting film obtained by peeling it off the support is laminated onto the positive electrode current collector.

[0127] According to one embodiment of the present invention, the solvent may be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and one of these may be used alone or as a mixture of two or more. The amount of solvent used is sufficient to dissolve or disperse the cathode active material, conductive material, binder, and dispersant, and to have a viscosity that allows for excellent thickness uniformity when applied for subsequent cathode manufacturing, taking into consideration the coating thickness of the slurry and the manufacturing yield.

[0128] Lithium-ion battery The present invention provides a lithium secondary battery including the positive electrode.

[0129] According to one embodiment of the present invention, the lithium secondary battery may include a positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte. The lithium secondary battery may further optionally include a battery container for housing the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member for sealing the battery container.

[0130] According to one embodiment of the present invention, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0131] According to one embodiment of the present invention, the negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel with surface treatment using carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. The negative electrode current collector usually has a thickness of 3 μm to 500 μm, and similar to the positive electrode current collector, the bonding force of the negative electrode active material may be strengthened by forming fine irregularities on the surface of the current collector. For example, it can be used in various forms such as film, sheet, foil, mesh, porous material, foam, and nonwoven fabric.

[0132] According to one embodiment of the present invention, the negative electrode active material layer may selectively include a binder and a conductive material together with the negative electrode active material.

[0133] According to one embodiment of the present invention, the negative electrode active material can be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO2. βExamples include lithium-doped and dedoped metal oxides such as (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites containing the metallic compound and carbonaceous material, such as Si-C composites or Sn-C composites; any one or more mixtures of these can be used. A metallic lithium thin film may also be used as the negative electrode active material. As for the carbon material, both low-crystallinity carbon and high-crystallinity carbon can be used. Typical low-crystalline carbons include soft carbon and hard carbon, while typical high-crystalline carbons include amorphous, plate-like, flaky, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbons such as petroleum or coal tar pitch-derived cokes. The anode active material may be present in an amount of 80% to 99% by weight based on the total weight of the anode active material layer.

[0134] According to one embodiment of the present invention, the binder of the negative electrode active material layer is a component that helps to bond the conductive material, the active material, and the current collector, and is usually added in an amount of 0.1% to 10% by weight based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0135] According to one embodiment of the present invention, the conductive material in the negative electrode active material layer is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10% by weight or less, preferably 5% by weight or less, based on the total weight of the negative electrode active material layer. Such conductive material is not particularly limited as long as it does not cause a chemical change in the battery and is conductive, and may be used, for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fibers and metal fibers; carbon fluoride; metal powders such as aluminum and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0136] According to one embodiment of the present invention, the negative electrode may be manufactured by coating a negative electrode active material layer forming composition, which is prepared by dissolving or dispersing a negative electrode active material and a binder and conductive material selectively in a solvent, onto a negative electrode current collector and drying it, or by casting the negative electrode active material layer forming composition onto another support, peeling it off the support, and then laminating the resulting film onto the negative electrode current collector.

[0137] According to one embodiment of the present invention, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. It can be used without particular limitations as long as it is a separator commonly used in lithium secondary batteries, and is particularly preferred if it has low resistance to ion movement of the electrolyte and excellent electrolyte impregnation ability. Specifically, porous polymer films such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer are preferred. Porous polymer films made from polyolefin polymers, or laminated structures of two or more layers thereof, can be used. Alternatively, ordinary porous nonwoven fabrics, such as those made from high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, coated separators containing ceramic components or polymeric substances may be used to ensure heat resistance or mechanical strength, and these may be used selectively as single-layer or multi-layer structures.

[0138] According to one embodiment of the present invention, the electrolyte may include, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries. Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0139] According to one embodiment of the present invention, the organic solvent can be used without particular limitations as long as it can act as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvents include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (propylene Carbonate solvents such as carbonate (PC); alcoholic solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and may include a double-bonded aromatic ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, carbonate solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge and discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred.

[0140] According to one embodiment of the present invention, the lithium salt can be used without particular limitations as long as it is a compound that can provide lithium ions used in lithium secondary batteries. Specifically, the anion of the lithium salt is F - Cl - , Br - , I - NO3 - , N(CN)2 - BF4 - CF3CF2SO3 - (CF3SO2)2N - , (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2) 2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - , and (CF3CF2SO2)2N - The lithium salt may be selected from the group consisting of LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2, etc. The concentration of the lithium salt is preferably in the range of 0.1M to 2.0M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and lithium ions can move effectively.

[0141] According to one embodiment of the present invention, in addition to the constituent components of the electrolyte, the electrolyte may further contain one or more additives for the purpose of improving the battery life characteristics, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme, hexaphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be present in an amount of 0.1% to 5% by weight relative to the total weight of the electrolyte.

[0142] The lithium secondary battery containing the positive electrode active material according to the present invention exhibits excellent capacity characteristics, output characteristics, and life characteristics stably, making it useful in portable devices such as mobile phones, notebook computers, and digital cameras, as well as in the electric vehicle field, including hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0143] The external shape of the lithium secondary battery of the present invention is not particularly limited, but may be cylindrical, rectangular, pouch-shaped, or coin-shaped, using a can.

[0144] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for small devices, but also suitably as a unit battery in medium- and large-sized battery modules containing a large number of battery cells.

[0145] Thus, according to one embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0146] According to one embodiment of the present invention, the battery module or battery pack can be used as a power source for one or more medium-to-large devices, including power tools; electric vehicles (EVs), hybrid electric vehicles, and plug-in hybrid electric vehicles (PHEVs); or power storage systems.

[0147] Hereinafter, embodiments of the present invention will be described in detail so that those with ordinary skill in the art to which the present invention pertains can easily implement it. However, the present invention can be realized in various different forms and is not limited to the embodiments described herein. [Examples]

[0148] Examples The present invention will be described in more detail below with reference to examples. However, the following examples are for illustrative purposes only and do not limit the scope of the present invention to these examples alone.

[0149] Example 1 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding and mixing lithium (Li) (Li / (Ni+Co+Mn)) to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0150] The mixture was calcined in an oxygen atmosphere at 850°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8833Co 0.0298 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0151] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8641 Co 0.0491 Mn 0.0777 Al 0.0066 Y 0.0010 Zr 0.0015 It was O2.

[0152] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8602 Co 0.0489 Mn 0.0773 Al0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0153] Example 2 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 1,470 ppm of Al(OH)3, 1,000 ppm of Y2O3, and 1,500 ppm of ZrO2 to the total weight of the transition metal complex hydroxide, along with LiOH, such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.00. A mixture was then prepared by adding Al(OH)3, 1,470 ppm of Y2O3, and 1,000 ppm of ZrO2 to this mixture and mixing it.

[0154] The mixture was subjected to primary calcination at 850°C for 6 hours under an oxygen atmosphere to obtain a first calcined product. Subsequently, the first calcined product was subjected to an average particle size (D) test at room temperature. 50 The particles were ground to a size of 9.8 μm.

[0155] The pulverized primary calcined product and LiOH were mixed so that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 0.04, and the mixture was secondary calcined at 800°C for 9 hours under an oxygen atmosphere to obtain a second calcined product. The second calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8833 Co 0.0298 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0156] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8641 Co 0.0491 Mn 0.0777 Al 0.0066 Y 0.0010 Zr 0.0015 It was O2.

[0157] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8602 Co 0.0489 Mn 0.0773 Al 0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0158] Example 3 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding and mixing lithium (Li) (Li / (Ni+Co+Mn)) to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0159] The mixture was calcined at 550°C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was then subjected to a temperature check at room temperature to obtain an average particle size (D 50 The particles were ground to a size of 9.8 μm.

[0160] The pulverized calcined product was calcined in an oxygen atmosphere at 850°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. By pulverizing the calcined product at room temperature, the average particle size (D 50 ) is 9.8 μm, LiNi 0.8833 Co 0.0298 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0161] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8641 Co 0.0491 Mn 0.0777 Al 0.0066 Y 0.0010 Zr 0.0015 It was O2.

[0162] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8602 Co 0.0489 Mn 0.0773 Al 0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0163] Example 4 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding and mixing lithium (Li) (Li / (Ni+Co+Mn)) to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0164] The mixture was calcined in an oxygen atmosphere at 880°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8833 Co 0.0298 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0165] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8641 Co 0.0491 Mn 0.0777 Al 0.0066 Y 0.0010 Zr 0.0015 It was O2.

[0166] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8602 Co 0.0489 Mn 0.0773 Al 0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0167] Example 5 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 10.2 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 2,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was then prepared.

[0168] The mixture was calcined in an oxygen atmosphere at 850°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8824 Co 0.0297 Mn 0.0793 Al 0.0050 Y 0.0021 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0169] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8632 Co 0.0491 Mn 0.0776 Al 0.0066 Y 0.0020 Zr 0.0015 It was O2.

[0170] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8593 Co 0.0489 Mn 0.0772 Al 0.0066 Y 0.0020 Zr 0.0015 B 0.0045 It was O2.

[0171] Example 6 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 10.2 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 2,940 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was then prepared.

[0172] The mixture was calcined in an oxygen atmosphere at 850°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8789 Co 0.0296 Mn 0.0790 Al 0.0100 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0173] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8597 Co 0.0490 Mn 0.0773Al 0.0115 Y 0.0010 Zr 0.0015 It was O2.

[0174] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8559 Co 0.0488 Mn 0.0769 Al 0.0115 Y 0.0010 Zr 0.0014 B 0.0045 It was O2.

[0175] Example 7 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.89 Co 0.03 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding and mixing lithium (Li) (Li / (Ni+Co+Mn)) with LiOH (10.2 μm) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 3,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0176] The mixture was calcined in an oxygen atmosphere at 850°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8815 Co 0.0297 Mn 0.0793 Al 0.0050Y 0.0010 Zr 0.0035 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0177] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 740°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles where primary particles had aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8623 Co 0.0491 Mn 0.0775 Al 0.0066 Y 0.0010 Zr 0.0035 It was O2.

[0178] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8584 Co 0.0489 Mn 0.0772 Al 0.0066 Y 0.0010 Zr 0.0034 B0.0045 It was O2.

[0179] Example 8 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.96 Co 0.03 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0180] The mixture was calcined in an oxygen atmosphere at 800°C for 6 hours, and then at 760°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 14.2 μm, LiNi 0.9528 Co 0.0298 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0181] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 was added to the lithium transition metal oxide in secondary particle form produced above at a content of 500 ppm relative to the total weight of the produced lithium transition metal oxide, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 700°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50By grinding the particles to a size of 14.5 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9320 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.0010 Zr 0.0015 It was O2.

[0182] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 14.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9278 Co 0.0489 Mn 0.0097 Al 0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0183] Example 9 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.96 Co 0.03 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 0.98. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0184] The mixture was subjected to primary calcination at 800°C for 6 hours under an oxygen atmosphere to obtain a first calcined product. Subsequently, the first calcined product was subjected to an average particle size (D) test at room temperature. 50 The particles were ground to a size of 14.2 μm.

[0185] The pulverized primary calcined product and LiOH were mixed so that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 0.04, and the mixture was secondary calcined at 760°C for 9 hours under an oxygen atmosphere to obtain a second calcined product. The second calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 14.2 μm, LiNi 0.9528 Co 0.0298 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0186] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 was added to the lithium transition metal oxide in secondary particle form produced above at a content of 500 ppm relative to the total weight of the produced lithium transition metal oxide, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 700°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 14.5 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9320 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.0010 Zr 0.0015 It was O2.

[0187] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 14.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9278 Co 0.0489 Mn 0.0097 Al 0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0188] Example 10 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.96 Co 0.03 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0189] The mixture was calcined at 550°C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was then subjected to a temperature check at room temperature to obtain an average particle size (D 50 The particles were ground to a size of 14.2 μm.

[0190] The pulverized calcined product was calcined in an oxygen atmosphere at 800°C for 6 hours, and then at 760°C for 9 hours to obtain a calcined product. By pulverizing the calcined product at room temperature, the average particle size (D 50 ) is 14.2 μm, LiNi 0.9528Co 0.0298 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0191] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 was added to the lithium transition metal oxide in secondary particle form produced above at a content of 500 ppm relative to the total weight of the produced lithium transition metal oxide, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 700°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 14.5 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9320 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.0010 Zr 0.0015 It was O2.

[0192] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 14.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9278 Co 0.0489 Mn 0.0097 Al0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0193] Example 11 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.96 Co 0.03 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0194] The mixture was calcined in an oxygen atmosphere at 830°C for 6 hours, and then at 760°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 14.2 μm, LiNi 0.9528 Co 0.0298 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0195] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 was added to the lithium transition metal oxide in secondary particle form produced above at a content of 500 ppm relative to the total weight of the produced lithium transition metal oxide, and then mixing them uniformly. The mixture was heat-treated in an oxygen atmosphere at 700°C for 3 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50By grinding the particles to a size of 14.5 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9320 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.0010 Zr 0.0015 It was O2.

[0196] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product and mixing. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 14.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9278 Co 0.0489 Mn 0.0097 Al 0.0066 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0197] Comparative Example 1 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.87 Co 0.05 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding and mixing lithium (Li) (Li / (Ni+Co+Mn)) to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) was 1.04. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0198] The mixture was calcined in an oxygen atmosphere at 850°C for 6 hours, and then at 800°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8635 Co 0.0496 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0199] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the lithium transition metal oxide produced in secondary particle form. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing B was formed on a lithium transition metal oxide in the form of secondary particles where primary particles were aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8596 Co 0.0494 Mn 0.0790 Al 0.0050 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0200] Comparative Example 2 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.87 Co 0.05 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 10.2 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.05. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0201] The mixture was calcined at 780°C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.8635 Co 0.0496 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in the form of secondary particles in which primary particles are aggregated was produced. Next, 100 parts by weight of the produced lithium transition metal oxide in the form of secondary particles and 100 parts by weight of water were stirred for 5 minutes, and then washed with water using a filter press. The washed product was dried at 130°C for 4 hours to produce a dried product.

[0202] A mixture was prepared by adding H3BO3 at a content of 1,000 ppm relative to the total weight of the lithium transition metal oxide to the dried product manufactured above and mixing. The mixture was heat-treated at 300°C for 5 hours in an air atmosphere to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing B was formed on a lithium transition metal oxide in the form of secondary particles where primary particles were aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.8558 Co 0.0492 Mn 0.0787 Al 0.0049 Y 0.0010 Zr 0.0015 B 0.0089 It was O2.

[0203] Comparative Example 3 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.87 Co 0.05 Mn 0.08 (D) transition metal composite hydroxide having a composition represented by (OH)2 50A mixture was prepared by adding and mixing lithium (Li) (Li / (Ni+Co+Mn)) with LiOH (12.2 μm) such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) was 1.05. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0204] The mixture was calcined at 780°C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 11.8 μm, LiNi 0.8635 Co 0.0496 Mn 0.0794 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in the form of secondary particles in which primary particles are aggregated was produced. Next, 100 parts by weight of the produced lithium transition metal oxide in the form of secondary particles and 100 parts by weight of water were stirred for 5 minutes, and then washed with water using a filter press. The washed product was dried at 130°C for 4 hours to produce a dried product.

[0205] A mixture was prepared by adding H3BO3 at a content of 1,000 ppm relative to the total weight of the lithium transition metal oxide to the dried product manufactured above and mixing. The mixture was heat-treated at 300°C for 5 hours in an air atmosphere to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 12.2 μm, a positive electrode active material was produced in which a coating portion containing B was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.8558 Co 0.0492 Mn 0.0787 Al 0.0049 Y 0.0010 Zr 0.0015 B 0.0089 It was O2.

[0206] Comparative Example 4 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.94 Co 0.05 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0207] The mixture was calcined in an oxygen atmosphere at 800°C for 6 hours, and then at 760°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 14.2 μm, LiNi 0.9330 Co 0.0496 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0208] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the lithium transition metal oxide produced in secondary particle form. The mixture was heat-treated at 330°C for 5 hours in an air atmosphere to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 14.2 μm, a positive electrode active material was produced in which a coating portion containing B was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9287 Co 0.0494 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0209] Comparative Example 5 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.94 Co 0.05 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0210] The mixture was calcined at 730°C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 14.2 μm, LiNi 0.9330 Co 0.0496 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in the form of secondary particles in which primary particles are aggregated was produced. Next, 100 parts by weight of the produced lithium transition metal oxide in the form of secondary particles and 100 parts by weight of water were stirred for 5 minutes, and then washed with water using a filter press. The washed product was dried at 130°C for 4 hours to produce a dried product.

[0211] A mixture was prepared by adding H3BO3 at a content of 1,000 ppm relative to the total weight of the lithium transition metal oxide to the dried product manufactured above and mixing. The mixture was heat-treated at 300°C for 5 hours in an air atmosphere to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 14.2 μm, a positive electrode active material was produced in which a coating portion containing B was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9246 Co 0.0492 Mn 0.0098 Al0.0050 Y 0.0010 Zr 0.0015 B 0.0089 It was O2.

[0212] Comparative Example 6 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.94 Co 0.05 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 10.2 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0213] The mixture was calcined at 730°C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 9.8 μm, LiNi 0.9330 Co 0.0496 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in the form of secondary particles in which primary particles are aggregated was produced. Next, 100 parts by weight of the produced lithium transition metal oxide in the form of secondary particles and 100 parts by weight of water were stirred for 5 minutes, and then washed with water using a filter press. The washed product was dried at 130°C for 4 hours to produce a dried product.

[0214] A mixture was prepared by adding H3BO3 at a content of 1,000 ppm relative to the total weight of the lithium transition metal oxide to the dried product manufactured above and mixing. The mixture was heat-treated at 300°C for 5 hours in an air atmosphere to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50By grinding the particles to a size of 10.2 μm, a positive electrode active material was produced in which a coating portion containing B was formed on a lithium transition metal oxide in the form of secondary particles where primary particles were aggregated. The total composition of the positive electrode active material including the coating portion was LiNi 0.9246 Co 0.0492 Mn 0.0098 Al 0.0050 Y 0.0010 Zr 0.0015 B 0.0089 It was O2.

[0215] Comparative Example 7 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.96 Co 0.03 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by adding 14.5 μm of lithium (Li) and LiOH to a transition metal (Ni+Co+Mn) such that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. To this mixture, Al(OH)3 was added at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was prepared.

[0216] The mixture was calcined in an oxygen atmosphere at 800°C for 6 hours, and then at 760°C for 9 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 14.2 μm, LiNi 0.9528 Co 0.0298 Mn 0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0217] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then uniformly mixing them. The mixture was heat-treated in an oxygen atmosphere at 700°C for 3 hours, and then at 500°C for 3 hours to obtain a coated product. The coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 14.5 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9320 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.0010 Zr 0.0015 It was O2.

[0218] Comparative Example 8 A secondary particle form formed by the aggregation of tens to hundreds of primary particles, Ni 0.96 Co 0.03 Mn 0.01 (D) transition metal composite hydroxide having a composition represented by (OH)2 50 A mixture was prepared by combining 5.2 μm of lithium (Li) with LiOH such that the molar ratio of lithium (Li) to the transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.03. Al(OH)3 was added to this mixture at concentrations of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal composite hydroxide, and the mixture was then prepared.

[0219] The mixture was calcined in an oxygen atmosphere at 830°C for 12 hours, and then at 760°C for 10 hours to obtain a calcined product. The calcined product was then pulverized at room temperature to obtain an average particle size (D 50 ) is 5.2 μm, LiNi 0.9528 Co 0.0298 Mn0.0099 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal oxide having a composition represented by O2 and in a secondary particle form in which primary particles are aggregated was produced.

[0220] A mixture was prepared by adding Co(OH)2 to the lithium transition metal oxide in secondary particle form produced above, such that the molar ratio of cobalt (Co) to the metal excluding lithium (Ni+Co+Mn+Al+Y+Zr) (Co / (Ni+Co+Mn+Al+Y+Zr)) was 0.02, and Al(OH)3 to a content of 500 ppm relative to the total weight of the lithium transition metal oxide in secondary particle form produced above, and then uniformly mixing them. The mixture was heat-treated in an oxygen atmosphere at 700°C for 5 hours, and then at 500°C for 3 hours to obtain a first coated product. The first coated product was heated at room temperature to obtain an average particle size (D 50 By grinding the particles to a size of 5.2 μm, a positive electrode active material was produced in which a coating portion containing Co and Al was formed on a lithium transition metal oxide in the form of secondary particles formed by the aggregation of primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9320 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.0010 Zr 0.0015 It was O2.

[0221] A mixture was prepared by adding H3BO3 at a content of 500 ppm relative to the total weight of the pulverized first coated product to the pulverized first coated product and mixing. The mixture was heat-treated at 300°C for 5 hours in an air atmosphere to obtain a second coated product. The second coated product was then heated at room temperature to obtain an average particle size (D 50 By grinding the primary particles to a size of 5.2 μm, a positive electrode active material was produced in which a coating portion containing Co, Al, and B was formed on a lithium transition metal oxide in the form of aggregated primary particles. The total composition of the positive electrode active material including the coating portion was LiNi 0.9278 Co 0.0489 Mn 0.0097 Al 0.0066 Zr0.0015 B 0.0045 It was O2.

[0222] Experimental example Experimental Example 1: Particle Analysis 1 The positive electrode active materials produced in Examples 1-11 and Comparative Examples 1-8 were each imaged using a scanning electron microscope (FEI quanta 250 FEG). The SEM images for Examples 1-11 are shown sequentially in Figures 1 to 11(A), and the SEM images for Comparative Examples 1-8 are shown sequentially in Figures 12 to 19(A). The average particle size of the primary particles present in each example and comparative example was measured from the SEM images and is shown in Table 1 below.

[0223] Then, the positive electrode active materials produced in Examples 1 to 11 and Comparative Examples 1 to 8 were ion-milled and photographed using a scanning electron microscope. The SEM images of Examples 1 to 11 are shown sequentially in Figures 1 to 11(B), and the SEM images of Comparative Examples 1 to 8 are shown sequentially in Figures 12 to 19(B). In Figures 1 to 19(B), the white rectangles are observed from the SEM images of the cross-section of secondary particles taken relative to the cross-section of the positive electrode active material, and represent the size of the cross-section of the secondary particles relative to the average particle size (D 50 In the SEM images of the cross-sections of secondary particles having a size within the specified range, a unit area of ​​5 μm x 5 μm was set within the cross-section of the secondary particle, and the number of primary particle cross-sections observed within this unit area is shown in Table 1 below.

[0224] Furthermore, an image analysis based on an artificial intelligence model was performed on the SEM image of Example 1 of the present invention, and the segmentation image showing the segmentation of multiple lithium composite transition metal oxides is shown in Figure 20, while the segmentation image of Comparative Example 2 is shown in Figure 21.

[0225] [Table 1]

[0226] Experimental Example 2: Particle Analysis 2 The positive electrode active materials produced in Examples 1, 2, and 8 were ion-milled, and then imaged using a transmission electron microscope (FEI Titan cubed G2 60-300). TEM images of the cross-sections of the primary particles of the positive electrode active materials in Examples 1, 2, and 8 are shown sequentially in Figures 22 to 24.

[0227] Referring to Figures 1 to 11 and Table 1, the positive electrode active materials of Examples 1 to 11 contain secondary particles formed by the aggregation of multiple primary particles, and it can be confirmed that the average particle size of these multiple primary particles, as measured from SEM images, is between 1.5 μm and 5.0 μm. Furthermore, it can be confirmed that these multiple primary particles include three or more disk-shaped primary particles. In this case, disk-shaped primary particles refer to primary particles observed from SEM images of the surface or cross-section of the secondary particles, where, when two boundary lines of primary particles located within an angle of 45° or less relative to the long axis are drawn, and a virtual tangent line with the most contact points is drawn for each, and a virtual line is drawn crossing the two tangent lines, the ipsilateral interior angle is between 150° and 210°. For reference, in Figures 1 to 11(B), when a hypothetical yellow tangent line with the most points of contact is drawn to two boundary lines of primary particles that exist within an angle of 45° or less, using the red major axis direction as a reference, a single hypothetical line (not shown) that crosses the two yellow tangent lines satisfies the condition that the ipsilateral interior angle is between 150° and 210°. Primary particles that fall into this category are defined as disc-shaped primary particles. Furthermore, it can be confirmed that the minor axis of these disc-shaped primary particles is 0.3 μm or more, and the aspect ratio (major axis / minor axis) is 1.5 or more. It can also be confirmed that the number of primary particle cross-sections within a unit area is between 1 and 100. Specifically, it can be confirmed that the number of primary particle cross-sections within a unit area is between 8 and 24.

[0228] Furthermore, referring to Figures 1 to 11 and Figures 22 to 24, it can be confirmed that in one embodiment of the present invention, the positive electrode active material has the largest proportion of the area of ​​the (003) plane among the crystal planes on the surface of the primary particles.

[0229] On the other hand, the positive electrode active materials of Comparative Examples 2, 3, 5, and 6 were found to have small average particle sizes of less than 500 nm, as measured from SEM images.

[0230] Referring to Figures 20 and 21, it can be confirmed that the positive electrode active material according to one embodiment of the present invention includes primary particles of a single crystal.

[0231] Experimental Example 3: Particle Analysis 3 The cathode active materials produced in Examples 1-11 and Comparative Examples 1-8 were imaged using a scanning electron microscope (FEI quanta 250 FEG) equipped with EBSD.

[0232] In particular, the size of the secondary particle cross-section was observed from the backscattered electron diffraction (EBSD) patterns of SEM images of the cross-section of secondary particles taken from the cross-section of the positive electrode active material of Examples 1-4, 8, 10, 11 and Comparative Example 5 (measured under the conditions of acceleration voltage 20kV, WD 16mm, measurement magnification 5,000x (width 16μm × height 16μm), step size 0.025μm), indicating that the size of the secondary particle cross-section was the average particle size (D) of the secondary particles. 50 In the EBSD patterns of the cross-sections of secondary particles having a size within the specified range, a unit area of ​​5 μm x 5 μm was set in the central region and the outer region within the cross-section of the secondary particle, respectively, as shown in Figures 25 (Example 1), 26 (Example 2), 27 (Example 3), 28 (Example 4), 29 (Example 8), 30 (Example 10), 31 (Example 11), and 32 (Comparative Example 5). The number of grain cross-sections observed within this unit area and the degree of single crystallinity calculated by the following formula 1 are shown together in Table 2 below.

[0233]

number

[0234] [Table 2]

[0235] Referring to Table 2, it can be confirmed that the positive electrode active materials of Examples 1 to 11 have between 1 and 150 grain cross-sections per unit area. Specifically, it can be confirmed that the number of grain cross-sections per unit area is between 3 and 19. Furthermore, the degree of single crystallinity is 0.15 μm. 3 The above can be confirmed. Specifically, the degree of single crystallinity is 0.86 μm. 3 or more, 1.57μm 3 It can be confirmed that the following is true.

[0236] Experimental Example 4: Particle Analysis 4 From the SEM image of the positive electrode active material obtained in Experimental Example 1, the degree of single-particle formation (Dv) corresponds to the diameter of the volume at the point where 50% of the volume cumulative distribution of primary particles present in each example and comparative example is obtained. 50 The following measurements were taken and are shown in Table 3 below.

[0237] Specifically, the area of ​​each primary particle was measured from the number of pixels corresponding to each of the n primary particles observed in the SEM images of the secondary particle surface taken on the surface of the positive electrode active material of Examples 1-11 and Comparative Examples 1-8, projected onto a two-dimensional plane. Subsequently, assuming that the surface of the primary particle is circular, the radius of the primary particle surface was derived using the radius of a circle having the same area as the surface area of ​​each primary particle. Using the radius, the volume value was calculated using the following formula 5, and the degree of single-particle formation (Dv) corresponding to the diameter of the volume at the point where the cumulative volume distribution of the primary particles reaches 50% was calculated. 50 The calculations were performed and are shown in Table 3 below.

[0238]

number

[0239] [Table 3]

[0240] Referring to Table 3, it can be confirmed that the cathode active materials of Examples 1 to 11 have a particle size of 1.2 μm or more and 3.8 μm or less. Specifically, it can be confirmed that the particle size is 1.65 μm or more and 3.55 μm or less.

[0241] Experimental Example 5: Particle Analysis 5 Electron spectroscopy (ESCA) was performed on the cathode active materials produced in Examples 1-11 and Comparative Examples 1-8 using a Thermo Fisher K-alpha XPS instrument to analyze the elemental distribution of Co and B coating layers on the surface. For depth profiling, etching was performed at a rate of 0.3 nm / 10 s using an Ar ion source, and the atomic %) content of B and Co in the coating layers with thicknesses from 0 to 100 nm was measured. The results are shown in Table 4 (B coating layer) and Table 5 (Co coating layer), respectively.

[0242] EPMA cross-sectional analysis was performed on the positive electrode active material of Example 1 to confirm its surface coating properties. First, the positive electrode active material of Example 1, carbon black conductive material, and PVDF binder were mixed in an N-methylpyrrolidone (NMP) solvent in a weight ratio of 95:2:3 to produce a positive electrode slurry. The produced positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and rolled to produce a positive electrode with an electrode porosity of 20%. To obtain a flat surface for EPMA cross-sectional analysis, the positive electrode was milled using a HITACHI IM-5000 instrument under an acceleration voltage of 6kV to obtain a cross-section of the positive electrode sample. Then, using a JEOL JXA-iHP200F instrument under an acceleration voltage of 15kV and a probe current of 50nA, a cross-sectional image of the positive electrode sample was observed and shown in Figure 31.

[0243] [Table 4]

[0244] [Table 5]

[0245] Referring to the SEM images in Figures 1 to 11, Tables 4 and 5, and Figure 31, it can be confirmed that the positive electrode active materials of Examples 1 to 11 have coatings containing Co and / or B formed on the surface of primary particles, the interface of primary particles, and / or the surface of secondary particles. Furthermore, it can be confirmed that these coatings have both island-like forms formed on the surface of primary particles, the interface of primary particles, and / or a portion of the surface of secondary particles, and forms of coating layers surrounding the surface of primary particles, the interface of primary particles, and / or the surface of secondary particles.

[0246] Experimental Example 6: Volume Cumulative Distribution Analysis For the positive electrode active materials produced in Examples 1-11 and Comparative Examples 1-8, a particle size analyzer (PSD, Malvern, martersizer 3500) was used to determine the D min , D 50 , and D max , the mode in the volume cumulative distribution by particle size, and the y-value (P) of the peak point at the uppermost end of the y-axis of the peak appearing in the mode in the volume cumulative distribution. MODE ), θ L , and θ R Measure θ L -θ R The calculations are shown in Table 6.

[0247] Then, the skewness value (S) is calculated using equation 3 below, and the y-value (P) of the peak point at the uppermost end of the y-axis of the peak that appears in the mode of the volume cumulative distribution is obtained. MODE The ratio of the skewness value (S) to the skewness value (S / P MODE The values ​​were calculated and are shown together in Table 6 below.

[0248]

number

[0249] Furthermore, for the positive electrode active materials of Examples 1 to 11 and Comparative Examples 2, 5, and 8, the cumulative volume distribution measured using a laser diffraction particle size analyzer is shown in frequency distribution graphs in Figures 34 (Example 1), 35 (Example 2), 36 (Example 3), 37 (Example 4), 38 (Example 5), 39 (Example 6), 40 (Example 7), 41 (Example 8), 42 (Example 9), 43 (Example 10), 44 (Example 11), 45 (Comparative Example 2), 46 (Comparative Example 5), and 47 (Comparative Example 8), respectively. These graphs show the cumulative volume distribution measured using a laser diffraction particle size analyzer for each positive electrode active material.

[0250] Then, for the positive electrode active materials of Examples 1 to 11 and Comparative Examples 2, 5, and 8, the cumulative volume distribution measured using a laser diffraction particle size analyzer is shown in frequency distribution graphs in Figures 48 (Example 1), 49 (Example 2), 50 (Example 3), 51 (Example 4), 52 (Example 5), 53 (Example 6), 54 (Example 7), 55 (Example 8), 56 (Example 9), 57 (Example 10), 58 (Example 11), 59 (Comparative Example 2), 60 (Comparative Example 5), and 61 (Comparative Example 8), respectively. These graphs show the volume cumulative distribution measured using a laser diffraction particle size analyzer for each positive electrode active material.

[0251] [Table 6]

[0252] Referring to Table 6, the positive electrode active material of Examples 2 to 11 is D 50 It can be confirmed that the size is between 7.0 μm and 20.0 μm. Also, (θ L -θ RIt can be confirmed that the value is between 6 and 20. Furthermore, the volume cumulative distribution measured using a laser diffraction particle size analyzer is shown in a frequency distribution graph where the x-axis represents the particle diameter as the x-value increases from left to right on a linear scale, and the y-axis represents the volume distribution as the y-value increases from bottom to top, and it can be confirmed that it shows positive skewness. On the other hand, the positive electrode active materials of Comparative Examples 2 to 8 have (θ L -θ R The value can be confirmed to be less than 6 or greater than 20.

[0253] Experimental Example 7: Measurement of Rolling Density An automatic pellet press (Carver, 3887.4) was used to adjust the zero point of the thickness in a cylindrical mold in a circular pellet holder with a diameter of 13 mm. Next, 3 g each of the positive electrode active material produced in Examples 1-11 and Comparative Examples 1-8 was placed in the circular pellet holder, and a force equivalent to 9,000 kgf was applied to measure the thickness of the formed pellets. Then, the volume of the pellets was calculated using Equation 4 below, and the rolling density was calculated using Equation 2 below, as shown in Table 7 below.

[0254] [Formula 4] Pellet volume (cm³) 3 ) = π (radius of the circular pellet holder) 2 × Pellet thickness

[0255] [Formula 2] Rolling density (g / cm³) 3 ) = Weight of positive electrode active material (g) / Volume of pellet (cm³) 3 )

[0256] [Table 7]

[0257] Referring to Table 7, the positive electrode active materials of Examples 1 to 11 have a rolling density of 3.60 g / cm³. 3 The above can be confirmed. Specifically, the rolling density is 3.66 g / cm³. 3 It can be confirmed that the above is true.

[0258] Experimental Example 8: Measurement of BET specific surface area The specific surface area was measured by nitrogen gas adsorption and desorption. Specifically, after measuring the weight of an empty cell, 3 g each of the positive electrode active material produced in Examples 1-11 and Comparative Examples 1-8 was taken and pretreated at 130°C for 3 hours. After measuring the weight of the cell after the pretreatment process, a Dewar flask containing liquid nitrogen was prepared and the cell was sealed. Under a nitrogen atmosphere, the BET specific surface area was measured from the amount of nitrogen gas adsorbed using a gas adsorption analyzer (Micromeritics TriStarr II), and is shown in Table 8 below.

[0259] [Table 8]

[0260] Referring to Table 8, the positive electrode active materials of Examples 1 to 11 have a BET specific surface area of ​​0.20 m². 2 / g or more, 0.35m 2 It can be confirmed that it is less than / g. Specifically, the BET specific surface area is 0.240m². 2 / g or more, 0.338m 2 It can be confirmed that the amount is less than / g.

[0261] Experimental Example 9: Manufacturing and Charge / Discharge Evaluation of Coin-Type Half-Cells A positive electrode slurry was prepared by mixing 95 parts by weight of the respective positive electrode active material produced in Examples 1 to 11 and Comparative Examples 1 to 8, 2 parts by weight of conductive material (Denka Co., Ltd., FX35), and 3 parts by weight of binder (Kureha Corporation, KF9709) in an N-methylpyrrolidone (NMP) solvent. The prepared positive electrode slurry was applied to one surface of an aluminum current collector with a thickness of 20 μm, and the positive electrode was produced by rolling it so that the porosity of the positive electrode active material layer was 24 volume%.

[0262] A lithium metal electrode was used as the negative electrode, and an electrode assembly was manufactured by interposing a porous polyethylene separator between the positive and negative electrodes. This assembly was placed inside a battery case, and an electrolyte was injected to manufacture a lithium secondary battery. The electrolyte was prepared by dissolving 1M LiPF6 in an organic solvent mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:3:4.

[0263] Using lithium secondary batteries containing the positive electrode active materials of Examples 1-11 and Comparative Examples 1-8 manufactured above, the charge capacity and discharge capacity were measured while charging in CC / CV mode to 4.25V with a constant current of 0.1C at 25°C (termination current 0.05C), and then discharging in CC mode to 2.5V, as shown in Table 9 below. In this case, 1C = 200mA / g was set.

[0264] Furthermore, the manufactured lithium secondary battery was charged in CC / CV mode at 45°C with a constant current of 0.5C to 4.25V (termination current 0.05C), and then discharged in CC mode with a constant current of 1.0C to 2.5V. This process was considered one cycle, and 50 cycles were repeated. The capacity retention rate was defined as the percentage of the discharge capacity of the 50th cycle to the discharge capacity of the 1st cycle, and is shown in Table 9 below.

[0265] [Table 9]

[0266] Experimental Example 10: Evaluation of High-Rate Discharge Capacity Using the lithium secondary battery manufactured in Experimental Example 9, the battery was charged in CC / CV mode at 25°C with a constant current of 0.5C to 4.25V (termination current 0.05C), and then discharged in CC mode at a constant current of 0.1C until it reached 2.5V, while measuring the discharge capacity. Similarly, the battery was charged in CC / CV mode at 25°C with a constant current of 0.5C to 4.25V (termination current 0.05C), and then discharged in CC mode at a constant current of 1.0C until it reached 2.5V, while measuring the discharge capacity. The percentages of the discharge capacity at 0.1C after 0.5C charging are shown in Table 10 below.

[0267] [Table 10]

[0268] Referring to Tables 9 and 10 above, it can be confirmed that the batteries containing the positive electrode active materials of Examples 1 to 11 have a large discharge capacity, high efficiency and high high-temperature capacity retention rate, low DC resistance and excellent rate characteristics. In contrast, the battery containing the positive electrode active material of Comparative Example 1 has problems with poor efficiency and high high-temperature capacity retention rate, the battery containing the positive electrode active material of Comparative Example 8 has problems with poor efficiency, the batteries containing the positive electrode active materials of Comparative Examples 1 to 6 have problems with poor rate characteristics, and the battery containing the positive electrode active material of Comparative Example 7 has problems with poor high-temperature capacity retention rate.

[0269] These results indicate that the positive electrode active material of the present invention is a positive electrode active material that can simultaneously solve the problems of both secondary particles and single particles in conventional high-nickel (High Ni) positive electrode active materials. By realizing a positive electrode active material in the form of secondary particles with primary particle size at the micron level, it has been confirmed that not only are cell characteristics such as improved lifespan and reduced gas generation of lithium secondary batteries improved, but the density characteristics are also excellent and the energy density can be improved.

Claims

1. It contains secondary particles formed by the aggregation of multiple primary particles, The aforementioned multiple primary particles have an average particle size of 1.5 μm or more and 5.0 μm or less, as measured from SEM images. The particle size of the primary particle is the particle size based on the major axis of the primary particle. In a frequency distribution graph showing the cumulative volume distribution measured using a laser diffraction particle size analyzer, with the x-axis representing the particle diameter increasing from left to right on a log scale, and the y-axis representing the volume distribution increasing from bottom to top on a log scale, When a triangle is drawn using the peak point at the uppermost end of the y-axis of the peak appearing at the mode (Mode), and the two points of tangency of the frequency distribution curve that are tangent at the full width at half maximum (FWHM) of the mode, Of the two points of tangency of frequency distribution curves that are tangent at half maximum, the interior angle (θ) at the left point of tangency. Ｌ ) and the interior angle (θ) at the right-side point of contact. Ｒ ) difference (θ Ｌ -θ Ｒ A positive electrode active material in which the ratio is between 6 and 20.

2. The ratio of the interior angle at the left tangency to the interior angle at the right tangency (θ) Ｌ / θ Ｒ The positive electrode active material according to claim 1, wherein the ratio is 1.100 or more and 2.000 or less.

3. The positive electrode active material according to claim 1, wherein the frequency distribution graph is a unimodal distribution graph.

4. The positive electrode active material according to claim 1, comprising a lithium transition metal composite oxide containing nickel, cobalt, and manganese.

5. The positive electrode active material according to claim 1, comprising a lithium transition metal composite oxide containing 60 mol% or more nickel among all transition metals.

6. The positive electrode active material according to claim 1, comprising a lithium transition metal composite oxide having an average composition represented by the following chemical formula 1. [Chemical formula 1] Li ｘ Ni ａ Co ｂ Mn ｃ M １ ｄ O ２ (In the above chemical formula 1, M １ is one or more selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, V, F, P, S, and Y. (0.9 ≤ x ≤ 1.3, 0.6 ≤ a < 1.0, 0 < b < 0.4, 0 < c < 0.4, 0 ≤ d ≤ 0.2, a + b + c + d = 1.)

7. The positive electrode active material according to claim 1, wherein the plurality of primary particles include single crystal primary particles.

8. The secondary particles are defined by the average particle size (D) based on the volume cumulative distribution measured using a laser diffraction particle size analyzer. ５０ The positive electrode active material according to claim 1, wherein the diameter is 7.0 μm or more and 20.0 μm or less.

9. A positive electrode comprising the positive electrode active material described in any one of claims 1 to 8.

10. A lithium secondary battery comprising a positive electrode according to claim 9, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte.

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