Positive electrode material, positive electrode, and lithium secondary battery

Abstract

The present invention relates to a positive electrode material having a high rolling density as well as being capable of improving energy density of an electrode and a battery including same, and to a positive electrode and a lithium secondary battery comprising same.

Description

Cathode material, cathode and lithium secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0149824 filed on October 29, 2024, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a cathode material, a cathode including the same, and a lithium secondary battery.

[0005]

[0006] With the recent technological advancements in electric vehicles and the like, the demand for high-capacity secondary batteries is increasing, and accordingly, research on high-nickel (High Ni) cathode active materials with excellent capacity characteristics is actively underway.

[0007] High-nickel cathode active materials formed with a secondary particle structure in which primary particles are aggregated undergo structural degradation during the charging and discharging of lithium secondary batteries, but also experience relatively significant changes in lattice structure constants, that is, changes in volume within the unit cell. These volume changes cause cracks within the cathode active material. Additionally, cracks may also occur within the cathode active material due to pressure during electrode rolling.

[0008] The cracks generated in this way within the high-nickel cathode active material become more severe during the charging and discharging process of the lithium secondary battery. Consequently, they act as voids that prevent the electrolyte from reaching or reduce conductivity, thereby degrading the lifespan characteristics of the lithium secondary battery or acting as a factor in increasing resistance.

[0009] Attempts are being made to manufacture single-particle cathode active materials as a means to minimize crack formation in such secondary particle structures. However, such single-particle cathode active materials have a problem in that the particle size distribution of the single-particle cathode active material obtained after grinding is large due to the non-uniform particle sizes. In addition, single-particle cathode active materials have a low specific surface area, which makes them vulnerable to cell resistance characteristics.

[0010] Therefore, there is a need for the development of a positive electrode active material that can simultaneously solve the problems of conventional secondary particles and single particles.

[0011] Meanwhile, Korean Registered Patent Publication No. 10-1785262 (Patent Document 1) discloses large-diameter secondary particles comprising primary particles aggregated into secondary particles, wherein the secondary particles comprise nickel-based lithium transition metal oxides, the average particle size of the primary particles is 3 to 5 μm, and the average particle size of the secondary particles is 10 to 20 μm. By including primary particles with an average particle size at the micron level, these large-diameter secondary particles can improve rolling density to minimize cracks caused by rolling, etc., and improve cell characteristics by improving the specific surface area through the secondary particle structure.

[0012] In order to manufacture a cathode active material in the form of secondary particles with a primary particle size at the micron level, as disclosed in Patent Document 1, it is necessary to perform heat treatment at a higher temperature than that for secondary particles with a primary particle size of less than 1 μm at the submicron level. However, as the heat treatment temperature increases, the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure, which causes a decrease in crystallinity and, consequently, a decrease in the performance of the cathode active material. In particular, since nickel is most susceptible to the degeneration of the layered structure of the lithium transition metal composite oxide into a rock salt structure at high heat treatment temperatures, the degeneration becomes more severe when the nickel content in the lithium transition metal composite oxide constituting the cathode active material increases. Therefore, conventionally, as a cathode active material in the form of secondary particles with a primary particle size at the micron level, it could only be applied to a Mid Ni cathode active material in which the nickel content among the transition metals of the lithium transition metal composite oxide is at the 50 mol% level, as in Patent Document 1, and it was not possible to manufacture a cathode active material in the form of secondary particles with a primary particle size at the micron level for a High Ni cathode active material in which the nickel content among the transition metals of the lithium transition metal composite oxide is high and has excellent capacity characteristics.

[0013] Accordingly, the inventors of the present invention have developed a positive electrode active material (single particle cluster) that can simultaneously solve the problems of conventional secondary particles and single particles in a high nickel (High Ni) positive electrode active material.

[0014] Additionally, the inventors of the present invention confirmed that when the above single particle cluster is used as a cathode material by mixing it with a conventional secondary particle cathode active material, the performance of the cathode material or the performance of the battery to which it is applied is improved compared to when the above single particle cluster is used alone, and thus completed the present invention.

[0015]

[0016] [Prior Art Literature]

[0017] [Patent Literature]

[0018] (Patent Document 1) KR 10-1785262 B1

[0019] (Patent Document 2) KR 10-2017-0119573 A

[0020]

[0021] The problem to be solved by the present invention is to provide a cathode material that can simultaneously solve the problems of conventional secondary particles and single particles, as well as further improve the performance of the cathode material or the performance of the battery to which it is applied.

[0022] Specifically, the present invention aims to solve the above-mentioned problems by mixing a large single-particle cluster and a small secondary particle cathode active material to increase the rolling density of the cathode material and to maintain the particle shape during rolling for electrode manufacturing, thereby providing a cathode material with improved electrochemical properties.

[0023] In addition, the present invention aims to provide a positive electrode and a lithium secondary battery comprising the above-mentioned positive electrode material.

[0024]

[0025] The present invention provides a positive electrode material, a positive electrode, and a lithium secondary battery.

[0026]

[0027] (1) The present invention comprises a first positive active material comprising a plurality of secondary particles aggregated from 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 a particle size based on the major axis of the primary particles; and a second positive active material comprising a plurality of secondary particles aggregated from primary particles, wherein the plurality of primary particles have an average particle size of less than 1.0 μm as measured from an SEM image, and the particle size of the primary particles is a particle size based on the major axis of the primary particles; wherein the first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer compared to the second positive active material. 50 The present invention provides an anode material in which the plurality of primary particles of the first anode active material include disk-type primary particles, wherein the disk-type primary particles are, in the case of primary particles observed from an SEM image of the surface or cross-section of secondary particles, when a virtual tangent line having the most contact points is drawn for each of the two boundary lines of primary particles existing within an angle of 45° or less with respect to the major axis direction, and a virtual line crossing the two tangent lines is drawn, the internal angle on the same side is 150° or more and 210° or less, the minor diameter is 0.3 μm or more, and the aspect ratio (major axis / minor diameter) is 1.5 or more.

[0028] (2) The present invention provides a cathode material in which, in (1) above, the first cathode active material is included in an amount of 10% or more and 90% or less of the total weight of the first cathode active material and the second cathode active material.

[0029] (3) The present invention provides an anode material in which, in (1) or (2), the primary particle in the shape of a disk has a short diameter of 0.7 μm or more.

[0030] (4) The present invention provides a cathode material in which, in any one of (1) to (3), the first cathode active material comprises a first lithium transition metal composite oxide containing 60 mol% or more of nickel among the total transition metals.

[0031] (5) The present invention provides a cathode material in which, in (4) above, the first lithium transition metal composite oxide has a composition represented by the following chemical formula 1.

[0032] [Chemical Formula 1]

[0033] Li x1 Ni a1 Co b1 Mn c1 M 1 d1 O2

[0034] In the above chemical formula 1,

[0035] 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

[0036] 0.9≤x1≤1.3, 0.6≤a1<1.0, 0 <b1<0.4, 0<c1<0.4, 0≤d1≤0.2, a1+b1+c1+d1=1이다.

[0037] (6) The present invention provides a cathode material in which, in any one of (1) to (5), the second cathode active material comprises a second lithium transition metal composite oxide containing 60 mol% or more of nickel among the total transition metals.

[0038] (7) The present invention provides a cathode material in which, in (6) above, the second lithium transition metal composite oxide has a composition represented by the following chemical formula 2.

[0039] [Chemical Formula 2]

[0040] Li x2 Ni a2 Co b2Mn c2 M 2 d2 O2

[0041] In the above chemical formula 2,

[0042] M 2 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

[0043] 0.9≤x2≤1.3, 0.6≤a2<1.0, 0 <b2<0.4, 0<c2<0.4, 0≤d2≤0.2, a2+b2+c2+d2=1이다.

[0044] (8) The present invention provides a cathode material in which, in any one of (1) to (7), the plurality of primary particles of the first cathode active material include single crystal primary particles.

[0045] (9) In any one of (1) to (8) above, the present invention is such that the first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 Provides a cathode material having a thickness of 7.0 μm or more and 20.0 μm or less.

[0046] (10) In any one of (1) to (9) above, the present invention is such that the second positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 Provides a cathode material having a thickness of 2.0 μm or more and 6.0 μm or less.

[0047] (11) The present invention provides an anode comprising an anode material according to any one of (1) to (11).

[0048] (12) The present invention provides a lithium secondary battery comprising a positive electrode according to (11); a negative electrode; a separator and an electrolyte interposed between the positive electrode and the negative electrode.

[0049]

[0050] The cathode material of the present invention comprises a first cathode active material in the form of secondary particles having a primary particle size of 1.5 μm or more and 5.0 μm or less, and an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer compared to the first cathode active material. 50 The second positive active material comprises a secondary particle type with a primary particle size of less than 1.0 μm and a plurality of primary particles of the first positive active material, and the primary particles of the first positive active material comprise primary particles of the disk type defined in this specification, so as to not only have a high rolling density, but also improve the energy density of the electrode and battery containing the same.

[0051]

[0052] Figure 1 is an SEM image of the positive electrode active material of Preparation Example 1.

[0053] Figure 2 is an SEM image of the positive electrode active material of Preparation Example 2.

[0054] Figure 3 is an SEM image of the positive electrode active material of Preparation Example 1.

[0055] Figure 4 is an SEM image of the positive electrode active material of Preparation Example 2.

[0056] Figure 5 is an SEM image of a cross-section of the positive electrode active material of Preparation Example 1.

[0057] Figure 6 is a segmentation image showing multiple cathode active materials segmented by performing image analysis based on an artificial intelligence model from the SEM image of the cathode active material of Preparation Example 1.

[0058] FIG. 7 is a graph showing the rolling density of each of the cathode materials of Examples 1 to 3 and Comparative Examples 1 to 2, and the rolling density predicted according to the mixing ratio of the first cathode active material and the second cathode active material.

[0059] FIG. 8 is a graph showing the energy density per unit volume of a battery containing each of the cathode materials of Examples 1 to 3 and Comparative Examples 1 to 2, and the energy density per unit volume predicted according to the mixing ratio of the first cathode active material and the second cathode active material.

[0060]

[0061] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0062] Terms and words used in the description and claims of the present invention should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0063]

[0064] In the present invention, the term 'primary particle' refers to a minimum particle unit that is distinguished as a single mass when the cross-section of the positive active material is observed through a scanning electron microscope (SEM), and may consist of a single crystal or multiple crystal grains.

[0065] In the present invention, the term 'secondary particle' refers to a secondary structure formed by the aggregation of a plurality of primary particles. The average particle size of the secondary particles can be measured using a particle size analyzer.

[0066] In the present invention, the term 'average particle size (D 50)' refers to the particle size at the 50% point of the cumulative volume distribution according to particle size. The above average particle size is determined by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), measuring the difference in diffraction patterns according to particle size as the particles pass through a laser beam to calculate the particle size distribution, and calculating the particle diameter at the point where the cumulative volume distribution according to particle size in the measuring device is 50%, thereby D 50 It can measure.

[0067] In the present invention, the term 'major axis of a primary particle' is the length of the longest line segment when a line is drawn passing through two points of the primary particle boundary in a primary particle observed from an SEM image of the surface or cross-section of a secondary particle.

[0068] In the present invention, the term 'short diameter of a primary particle' is the length of the shortest line segment when a line is drawn passing through two points of the primary particle boundary in a primary particle observed from an SEM image of the surface or cross-section of a secondary particle.

[0069]

[0070] cathode material

[0071] The cathode material according to the present invention comprises: a first cathode active material comprising secondary particles aggregated from 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 a second cathode active material comprising secondary particles aggregated from a plurality of primary particles, wherein the plurality of primary particles have an average particle size of less than 1.0 μm 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; wherein the first cathode active material has an average particle diameter (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer compared to the second cathode active material. 50 The above-mentioned primary particles of the first positive active material include disk-type primary particles, and the disk-type primary particles are, in the case of primary particles observed from an SEM image of the surface or cross-section of secondary particles, when a virtual tangent line is drawn with the most contact points for each of the two boundary lines of the primary particles existing within an angle of 45° or less with respect to the major axis direction, and a virtual line is drawn crossing the two tangent lines, the internal angle on the same side is 150° or more and 210° or less, the minor axis is 0.3 μm or more, and the aspect ratio (major axis / minor axis) is 1.5 or more.

[0072]

[0073] As described above, the inventors of the present invention developed a cathode active material (single particle cluster) capable of simultaneously solving the problems of conventional secondary particles and single particles in a high nickel (High Ni) cathode active material. However, they confirmed that when the cathode active material is mixed with a conventional secondary particle cathode active material and used as a cathode material, the performance of the cathode material or the performance of the battery to which it is applied is further improved compared to when the cathode active material is used alone, and thus completed the present invention.

[0074] Specifically, the inventors of the present invention confirmed that when a first positive electrode active material and a second positive electrode active material are mixed, the rolling density and the energy density of the electrode or battery are superior to the effects expected according to the mixing ratio, and thus completed the present invention.

[0075] In particular, the inventors of the present invention have confirmed that when the plurality of primary particles of the first positive active material include primary particles of the disk type defined in the present invention, the linear pressure during roll pressing is dispersed due to the disk-type primary particles, thereby further mitigating the particle breakage phenomenon of the positive material during the rolling process for manufacturing the electrode, and further improving the energy density of the electrode or battery containing the positive material.

[0076] Meanwhile, if the above-mentioned cathode material does not contain disk-type primary particles, the linear pressure is not dispersed during roll pressing, and particle breakage increases due to the buffering effect. In addition, direct linear pressure is applied to the current collector, which may cause elongation of the current collector. For example, if the current collector is an aluminum thin film, the aluminum thin film may stretch.

[0077]

[0078] According to the present invention, the first positive active material may be included in an amount of 10% or more and 90% or less of the total weight of the first positive active material and the second positive active material. More specifically, the first positive active material may be 10% or more, 11% or more, 12% or more, 13% or more, 14% or more, 15% or more, 16% or more, 17% or more, 18% or more, 19% or more, 20% or more of the total weight of the first positive active material and the second positive active material, and may be 80% or less, 81% or less, 82% or less, 83% or less, 84% or less, 85% or less, 86% or less, 87% or less, 88% or less, 89% or less, and 90% or less of the total weight. When the first positive electrode active material is included in the above range, the second positive electrode active material is appropriately filled between the first positive electrode active materials, so that the rolling density of the positive electrode material can be further improved, and as a result, the energy density and lifespan characteristics of the battery to which it is applied can be improved.

[0079]

[0080] Below, each positive active material is described in detail.

[0081]

[0082] First positive active material

[0083] According to the present invention, the first positive active material comprises secondary particles aggregated from a plurality of primary particles, and 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.

[0084] According to the present invention, the secondary particle is a secondary particle formed by the aggregation of a plurality of primary particles, and may be formed by the aggregation of at least two, specifically, at least three or more primary particles.

[0085] According to 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 have an average particle size of 5.0 μm or less, 4.9 μm or less, 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, It may be 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 plurality of primary particles from an SEM image, the particle size of each primary particle may be the particle size based on the major axis of the primary particle. Within this range, the rolling density of the first positive electrode active material can be further improved, and the lifespan of the lithium secondary battery can be further improved.

[0086]

[0087] According to the present invention, the plurality of primary particles of the first positive active material include disk-type primary particles, and in this case, the cell lifespan and energy density are excellent. According to the present invention, the plurality of primary particles of the first positive active material may include three or more disk-type primary particles.

[0088] The above-mentioned disk-shaped primary particle refers to a primary particle observed from an SEM image of the surface or cross-section of a secondary particle, wherein, for two boundary lines of the primary particle existing within an angle of 45° or less relative to the major axis direction, a virtual tangent line having the most contact points is drawn for each, and a virtual line crossing the two tangent lines is drawn, and the internal angle on the same side is 150° or more and 210° or less, the minor diameter of the primary particle is 0.3 μm or more, and the aspect ratio (major axis / minor diameter) is 1.5 or more. As a specific example, the above-mentioned disk-shaped primary particle may have a minor diameter 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, when the short diameter of the disk-shaped primary particle is 0.3 μm or more and the aspect ratio (major diameter / short diameter) is 1.5 or more, the area ratio of the (003) plane among the crystal planes of the surface of the primary particle may be the largest.

[0089] The above disk-shaped primary particle may mean that, in the case of a primary particle observed from an SEM image of the surface or cross-section of a secondary particle, when a virtual tangent line with the most contact points is drawn for each of the two boundary lines of the primary particle existing within an angle of 45° or less with respect to the major axis direction, and a virtual line is drawn crossing the two tangent lines, the internal angle on the same side is 150° or more and 210° or less, and the area ratio of the (003) plane among the crystal planes of the primary particle surface part of the primary particle is the largest. Here, when the area ratio of the (003) plane among the crystal planes of the primary particle surface part of the disk-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 fact that the area ratio of the (003) plane among the crystal planes of the primary particle surface is the largest can be confirmed from the fact that the minor diameter of the primary particle is 0.3 μm or more and the aspect ratio (major diameter / minor diameter) is 1.5 or more.

[0090]

[0091] According to the present invention, the first positive electrode active material may comprise a first lithium transition metal composite oxide comprising nickel, cobalt, and manganese. As a specific example, the first positive electrode active material may comprise a first lithium transition metal composite oxide comprising 60 mol% or more of nickel among the total transition metals. The first lithium transition metal composite oxide may be a primary particle, a secondary particle, and the first positive electrode active material itself comprising these, and as a specific example, the first positive electrode active material may comprise a secondary particle formed by aggregating a plurality of primary particles composed of the first lithium transition metal composite oxide.

[0092] According to the present invention, the first positive electrode active material may comprise a first lithium transition metal composite oxide having a composition represented by the following chemical formula 1.

[0093] [Chemical Formula 1]

[0094] Li x1 Ni a1 Co b1 Mn c1 M 1 d1 O2

[0095] In the above chemical formula 1,

[0096] 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, where 0.9≤x1≤1.3, 0.6≤a1<1.0, 0 <b1<0.4, 0<c1<0.4, 0≤d1≤0.2, a1+b1+c1+d1=1이다.

[0097] In the above chemical formula 1, x1 is the molar ratio of lithium to the transition metal in the first lithium transition metal complex oxide, which 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.

[0098] In the above Chemical Formula 1, a1, b1, c1, and d1 are, respectively, nickel (Ni), cobalt (Co), manganese (Mn) among transition metals and a doping element (M 1It may be a mole fraction for ). As a specific example, the above a1 may be a mole fraction for nickel (Ni) among transition metals, which is 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. Additionally, the above b1 may be a mole fraction of cobalt (Co) among the transition metals that is 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 c1 may be a mole fraction of manganese (Mn) among the transition metals that is 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 d1 is a doping element (M) among the transition metals 1As a mole fraction for ), it may be 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, and additionally, 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 It may be 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. When the composition of the first lithium transition metal composite oxide is adjusted as above, the capacity can be further improved.

[0099] According to the present invention, the plurality of primary particles of the first positive active material may include single-crystal primary particles, and in this case, the rolling density of the first positive active material can be further improved. The single-crystal primary particles refer to primary particles composed of a single crystal.

[0100] According to the present invention, the first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 ) may be 7.0 μm or more and 20.0 μm or less. As a specific example, the first cathode active material has an average particle size (D 50) may be 7.0 µm or more, 7.1 µm or more, 7.2 µm or more, 7.3 µm or more, 7.4 µm or more, 7.5 µm or more, 7.6 µm or more, 7.7 µm or more, 7.8 µm or more, 7.9 µm or more, 8.0 µm or more, 8.1 µm or more, 8.2 µm or more, 8.3 µm or more, 8.4 µm or more, 8.5 µm or more, 8.6 µm or more, 8.7 µm or more, 8.8 µm or more, 8.9 µm or more, or 9.0 µm or more, and may also be 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, 17.5 μm or less, 17.4 μm or less, 17.3 μm or less, 17.2 μm or less, 17.1 μm or less, 17.0 μm or less, 16.9 μm or less, 16.8 μm or less, 16.7 μm or less, 16.6 μm It may be 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. Within this range, the rolling density of the first positive active material can be further improved, and the lifespan can be further improved.

[0101] As a specific example, the first cathode active material is a high-nickel cathode active material comprising a first lithium transition metal composite oxide containing 60 mol% or more of nickel among the total transition metals, wherein a plurality of primary particles are primary particles having a particle size of 0.5 μm or more and 5.0 μm or less, specifically primary particles at the micron level with a particle size of 1.0 μm or more, and more specifically, primary particles having an average particle size of 2.0 μm or more and 3.5 μm or less as measured from an SEM image, and the average particle size (D) formed by the aggregation of a plurality of primary particles. 50 It may include secondary particles with a diameter of 7.0 μm or more and 20.0 μm or less, and may be described as a cluster of large particles in the sense that primary particles in the form of single particles aggregate to form large particles in the form of secondary particles.

[0102] As described above in the background technology of the present invention, in order to manufacture a cathode active material in the form of secondary particles with a primary particle size at the micron level, it is necessary to perform heat treatment at a higher temperature than for secondary particles with a primary particle size of less than 1 μm at the submicron level. However, as the heat treatment temperature increases, the layered structure of the lithium transition metal composite oxide degenerates into a rock salt structure, which causes a decrease in crystallinity and, consequently, a decrease in the performance of the cathode active material. In particular, since nickel is most susceptible to the degeneration of the layered structure of the lithium transition metal composite oxide into a rock salt structure at high heat treatment temperatures, the degeneration becomes more severe when the nickel content in the lithium transition metal composite oxide constituting the cathode active material increases. Therefore, conventionally, as a cathode active material in the form of secondary particles with a primary particle size at the micron level, it could only be applied to mid-nickel cathode active materials in which the nickel content among the transition metals of the lithium transition metal composite oxide is at the 50 mol% level, and it was not possible to manufacture a cathode active material in the form of secondary particles with a primary particle size at the micron level for high-nickel cathode active materials in which the nickel content among the transition metals of the lithium transition metal composite oxide is high and has excellent capacity characteristics.

[0103] However, the first cathode active material of the present invention has a high nickel content among the transition metals of the first lithium transition metal composite oxide, so even if the layered structure of the first lithium transition metal composite oxide degenerates into a rock salt structure at a high heat treatment temperature, the rock salt structure is recovered to a layered structure, thereby solving the aforementioned problem. Specifically, unlike conventional mid-nickel cathode active materials, the first cathode active material of the present invention is a high-nickel cathode active material comprising a first lithium transition metal composite oxide containing 60 mol% or more of nickel among the total transition metals, and while including secondary particles with a primary particle size at the micron level, the rock salt structure formed by the high heat treatment temperature is recovered to a layered structure, so the crystallinity of the first lithium transition metal composite oxide is excellent, and thus the problems of the conventional secondary particles and single particles can be solved simultaneously. The first positive electrode active material of the present invention can be manufactured by restoring the rock salt structure formed by the high heat treatment temperature as described above into a layered structure, and although the method of restoring the rock salt structure into a layered structure is not limited, according to one embodiment of the present invention, the method of restoring the rock salt structure into a layered structure may be to apply a cobalt (Co) coating to the first lithium transition metal composite oxide containing the rock salt structure formed by the high heat treatment temperature.

[0104] The first positive electrode active material comprises: the peak point at the uppermost y-axis of the peak appearing at the mode in a frequency distribution graph in which the volume cumulative distribution measured using a laser diffraction particle size analyzer is represented on a log scale for particle diameter with x-values ​​increasing from left to right on the x-axis and weight distribution with y-values ​​increasing from bottom to top on the y-axis; and when a triangle is plotted at the two points of tangency of the frequency distribution curve tangent at the full width at half maximum (FWHM) of the mode, the interior angle (θ) at the left tangent of the two tangents of the frequency distribution curve tangent at the full width at half maximum. L ) and the interior angle at the right tangent (θR The difference of )(θ L - θ R ) may be between 6 and 20. As a specific example, the interior angle (θ at the left tangent point) L ) and the interior angle at the right tangent (θ R The difference of )(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 first positive active material is the ratio of the interior angle at the left junction to the interior angle at the right junction (θ L / θ R ) may be 1.100 or more and 2.000 or less. As a specific example, the ratio of the interior angle at the left tangent to the interior angle at the right tangent (θ L / θ R) is 1.100 or more, 1.110 or more, 1.120 or more, 1.130 or more, 1.140 or more, 1.150 or more, 1.160 or more, 1.170 or more, 1.180 or more, 1.190 or more, 1.200 or more, 1.210 or more, 1.220 or more, 1.230 or more, 1.240 or more, 1.250 or more, 1.260 or more, 1.270 or more, 1.280 or more, 1.290 or more, 1.300 or more, 1.310 or more, 1.320 or more, 1.330 or more, 1.340 or more, 1.350 or more, 1.360 or more, 1.370 or more, 1.380 or more, 1.390 or more, It may be 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.

[0105] The first positive active material may exhibit positive skewness in a frequency distribution graph in which the volume cumulative distribution measured using a laser diffraction particle size analyzer is represented on a linear scale for particle diameter with x-values ​​increasing from left to right on the x-axis, and the weight distribution with y-values ​​increasing from bottom to top on the y-axis. Here, the frequency distribution graph may be a unimodal distribution graph.

[0106] The above-mentioned first positive active material is the y-value (P) of the peak point at the uppermost end of the y-axis of the peak appearing at the mode according to the volume cumulative distribution. MODE The ratio of the skewness value (S) to ) (S / P MODE) may be 0.037 or higher and 0.150 or lower. As a specific example, the first cathode active material is the y-value (P) of the peak point at the uppermost end of the y-axis of the peak appearing in the mode according to the volume cumulative distribution. MODE The ratio of the skewness value (S) to ) (S / P MODE ) is 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 It may be greater than or equal to 0.097, greater than or equal to 0.098, greater than or equal to 0.099, or greater than or equal to 0.100, and may be less than or equal to 0.150, less than or equal to 0.140, less than or equal to 0.130, less than or equal to 0.120, or less than or equal to 0.110. Here, the skewness value (S) may be calculated from the following Equation 1.

[0107] [Equation 1]

[0108]

[0109] The above-mentioned first cathode active material has a BET specific surface area of ​​0.20 m² as measured by nitrogen adsorption BET specific surface area analysis. 2 / g or more, 0.35 m 2 It may be / g or less. As a specific example, the BET specific surface area of ​​the first cathode active material measured by nitrogen adsorption BET specific surface area analysis is 0.20 m² 2 / g or more, 0.21 m 2 / g or more, 0.22 m 2 / g or more, 0.23 m 2 / g or more, 0.24 m 2 / g or more, 0.25 m 2 / g or more, 0.26 m 2 / g or more, 0.27 m 2 / g or more, 0.28 m 2 / g or more, 0.29 m 2 / g or more, 0.30 m 2 / g or more, or 0.31 m 2 It may be greater than / g, and also, 0.35 m 2 / g or less, or 0.34 m 2 It may be less than / g. Within this range, DC resistance can be reduced, and rolling density can be improved.

[0110] The above-mentioned first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 ) is 7.0 μm or more and 20.0 μm or less, and 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 diameter (D) of the secondary particle 50 For a cross-section of a secondary particle having a size within the range, the number of cross-sections of primary particles identified within a unit area of ​​5 μm x 5 μm in width within the cross-section of the secondary particle may be 1 or more and 100 or less.

[0111] 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) of the secondary particle. 50 For a cross-section of a secondary particle having a size within the range, the number of cross-sections of a primary particle identified within a unit area of ​​5 μm x 5 μm in width within the cross-section of the secondary particle refers to the number of all cross-sections of primary particles that include at least some of the cross-sections of the primary particles, in addition to including all cross-sections of the primary particles identified within the unit area. Furthermore, the unit area of ​​5 μm x 5 μm in width within the cross-section of the secondary particle is a unit area at any point within the cross-section of the secondary particle, and the location is not limited as long as it is within the cross-section of the secondary particle.

[0112] The above-mentioned first positive active material is such that the size of the cross-section of the secondary particle, as observed from the SEM image of the cross-section of the secondary particle, is the average particle size (D) of the secondary particle. 50For a cross-section of a secondary particle having a size within the range, the number of primary particle cross-sections identified within a unit area of ​​5 μm x 5 μm in width within the cross-section of the secondary particle may be 1 or more and 100 or fewer. Specifically, 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. Additionally, it may be 100 or fewer, 95 or fewer, 90 or fewer, 85 or fewer, 80 or fewer, 75 or fewer, 70 or fewer, 65 or fewer, 60 or fewer, 55 or fewer, 50 or fewer, 45 or fewer, 40 or fewer, 35 or fewer, 30 or fewer, or 25 or fewer. When satisfying such a range, the first cathode active material comprises a plurality of primary particles having a particle size similar to conventional single particles, ranging from 0.5 μm or more to 5.0 μm or less, specifically primary particles at the micron level with a particle size of 1.0 μm or more, and more specifically, primary particles with an average particle size of 2.0 μm or more to 3.5 μm or less as measured from an SEM image, with an average particle size (D) formed by the aggregation of these primary particles. 50 It may indicate that it contains secondary particles of large diameter, ranging from 7.0 μm or more to 20.0 μm or less.

[0113] The above first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer for the above secondary particles. 50 ) is 7.0 μm or more and 20.0 μm or less, and the cross-sectional size of the secondary particle observed from the backscattered electron diffraction (EBSD) pattern of the SEM image of the secondary particle cross-section (measured under conditions of acceleration voltage 20 kV, WD 16 mm, measurement magnification 5,000x (width 16 μm * height 16 μm), step size 0.025 μm) is the average particle diameter (D) of the secondary particle. 50For a cross-section of a secondary particle having a size within the range of ), the number of grain cross-sections identified within a unit area of ​​5 μm x 5 μm (width x height) within the cross-section of the secondary particle may be 1 or more and 150 or less. The size of the cross-section of the secondary particle observed from the backscattered electron diffraction (EBSD) pattern of the SEM image of the cross-section of the secondary particle (measured under conditions of acceleration voltage 20 kV, WD 16 mm, measurement magnification 5,000x (width 16 μm x height 16 μm), step size 0.025 μm) is the average particle diameter (D) of the secondary particle. 50 For a cross-section of a secondary particle having a size within the range, the number of grain cross-sections identified within a unit area of ​​5 μm x 5 μm in width within the cross-section of the secondary particle refers to the total number of grain cross-sections that include at least some of the grain cross-sections in addition to all grain cross-sections identified within the unit area. Furthermore, the unit area of ​​5 μm x 5 μm in width within the cross-section of the secondary particle is a unit area at any point within the cross-section of the secondary particle, and the location is not limited as long as it is within the cross-section of the secondary particle.

[0114] The above-mentioned first cathode active material is such that the cross-sectional size of the secondary particle, as observed from the backscattered electron diffraction (EBSD) pattern of the SEM image of the cross-section of the secondary particle (measured under conditions of acceleration voltage 20 kV, WD 16 mm, measurement magnification 5,000x (width 16 μm * height 16 μm), step size 0.025 μm), is the average particle diameter (D) of the secondary particle. 50For a cross-section of a secondary particle having a size within the range, the number of grain cross-sections identified within a unit area of ​​5 µm in width * 5 µm in length within the cross-section of the secondary particle may be 1 or more and 150 or fewer; as a specific 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, or 9 or more; additionally, 150 or fewer, 145 or fewer, 140 or fewer, 135 or fewer, 130 or fewer, 125 or fewer, 120 or fewer, 115 or fewer, 110 or fewer, 105 or fewer, 100 or fewer, 95 or fewer, 90 or fewer, 85 or fewer, 80 or fewer, 75 or fewer, 70 or fewer, 65 or fewer, 60 or fewer, 55 or fewer The number may be 50 or fewer, 45 or fewer, 40 or fewer, 35 or fewer, 30 or fewer, 25 or fewer, or 20 or fewer. When such a range is satisfied, the first cathode active material is formed by the aggregation of a plurality of primary particles having a particle size similar to conventional single particles, such as primary particles with a particle size of 0.5 μm or more and 5.0 μm or less, specifically primary particles at the micron level with a particle size of 1.0 μm or more, and more specifically, primary particles with an average particle size of 2.0 μm or more and 3.5 μm or less as measured from an SEM image, with an average particle size (D) 50 It may indicate that it contains secondary particles of large diameter, ranging from 7.0 μm or more to 20.0 μm or less.

[0115] The first positive active material has a degree of single crystallinity of 0.15 μm calculated from the following Equation 2. 3 It could be an abnormality.

[0116] [Equation 2]

[0117]

[0118] In Equation 2 above, radius(grain) is the size of the cross-section of the secondary particle observed from the backscattered electron diffraction (EBSD) pattern on the SEM image of the cross-section of the secondary particle (measured under 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 diameter (D) of the secondary particle. 50 Among all grain cross-sections identifiable in the cross-section of a secondary particle having a size within the range, the area of ​​the grain cross-section is 0.196 μm 2 For the cross-section of the grain, it is the radius of the cross-section of the grain assuming the cross-section of the grain is circular, and n is the number of grains.

[0119] The first positive active material has a degree of single crystallinity of 0.15 μm calculated from Equation 2. 3 Above, 12.70 µm 3 It may be less than or equal to. As a specific example, the first positive active material has a degree of single crystallinity calculated from Equation 2 of 0.15 μm. 3 Above, 0.20 µm 3 Above, 0.25 µm 3 Above, 0.30 µm 3 Above, 0.35 µm 3 Above, 0.40 µm 3 Above, 0.45 µm 3 Above, 0.50 µm 3 Above, 0.55 µm 3 Above, 0.60 µm 3 Above, 0.65 µm 3 Above, 0.70 µm 3 Above, 0.75 µm 3 Above, 0.80 µm 3 Above, 0.85 µm 3 Above, 0.90 µm 3 Above, 0.95 µm 3 Above, 1.00 µm 3 Greater than, or 1.05 µm 3It may be more than that, and although the upper limit is not specifically restricted, 20.00 µm 3 Below, 19.00 µm 3 Below, 18.00 µm 3 Below, 17.00 µm 3 Below, 16.00 µm 3 Less than or equal to 15.00 µm 3 Below, 14.00 µm 3 Below, 13.00 µm 3 Less than, or 12.70 µm 3 It may be less than or equal to

[0120] The first positive electrode active material may comprise a first lithium transition metal composite oxide comprising aluminum (Al), yttrium (Y), and zirconium (Zr). As a specific example, the first positive electrode active material may comprise aluminum (Al), yttrium (Y), and zirconium (Zr) as doping elements. The aluminum (Al) may be included in an amount of 500 ppm to 3,000 ppm with respect to the total weight of the first lithium transition metal composite oxide. As a specific example, the aluminum (Al) may be included in an amount of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more with respect to the total weight of the first lithium transition metal composite oxide, and may also be included in an amount of 3,000 ppm or less, 2,500 ppm or less, or 2,000 ppm or less. The yttrium (Y) may be included in an amount of 100 ppm to 2,000 ppm with respect to the total weight of the first lithium transition metal composite oxide. As a specific example, the yttrium (Y) may be included in an amount of 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, or 500 ppm or more with respect to the total weight of the first lithium transition metal composite oxide, and may also be included in an amount 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. The zirconium (Zr) may be included in an amount of 500 ppm to 5,000 ppm with respect to the total weight of the first lithium transition metal composite oxide.As a specific example, the zirconium (Zr) may be included in an amount of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more with respect to the total weight of the first lithium transition metal composite oxide, and may also be included 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.

[0121] The above-mentioned first positive active material may comprise a first lithium transition metal complex oxide having an average composition represented by the following chemical formula 3.

[0122] [Chemical Formula 3]

[0123] Li x3 [Ni a3 Co b3 Mn c3 Al e3 Y f3 Zr g3 M 1 d3 ]O 2-y3 A y3

[0124] In the above chemical formula 3, M 1 is one or more 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 selected from the group consisting of F, Cl, Br, I, and S, where 0.9≤x3≤1.3, 0.6≤a3<1.0, 0 <b3<0.4, 0<c3<0.4, 0≤d3≤0.2, 0<e3≤0.01, 0<f3≤0.0006, 0<g3≤0.0005, a3+b3+c3+d3+e3+f3+g3=1, 0≤y3≤0.2이다.

[0125] In the above chemical formula 3, x3 is the molar ratio of lithium to the transition metal in the first lithium transition metal complex oxide, which 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.

[0126] In the above chemical formula 3, a3, b3, c3, d3, e3, f3, and g3 are, respectively, nickel (Ni), cobalt (Co), manganese (Mn) among transition metals, and a doping element (M 1 It may be a mole fraction for aluminum (Al), yttrium (Y), and zirconium (Zr). As a specific example, the above a3 may be a mole fraction for nickel (Ni) among transition metals, which is 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. Additionally, the above b3 may be a mole fraction of cobalt (Co) among the transition metals that is 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 c3 may be a mole fraction of manganese (Mn) among the transition metals that is 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 d3 is a doping element (M) among the transition metals 1As a mole fraction for ), it may be 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, and additionally, 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 It may be less than or equal to 0.06, less than or equal to 0.05, less than or equal to 0.04, less than or equal to 0.03, less than or equal to 0.02, or less than or equal to 0.01. The above e3 is a mole fraction for aluminum (Al) among transition metals, and may be greater than 0, greater than or equal to 0.001, greater than or equal to 0.002, greater than or equal to 0.003, greater than or equal to 0.004, or greater than or equal to 0.005, and may also be less than or equal to 0.01, less than or equal to 0.009, or less than or equal to 0.008. The above f3 is a mole fraction for yttrium (Y) among transition metals, and may be greater than 0, greater than or equal to 0.0001, greater than or equal to 0.0002, or greater than or equal to 0.0003, and may also be less than or equal to 0.0006, less than or equal to 0.0005, or less than or equal to 0.0004. The above g3 is a mole fraction of zirconium (Zr) among transition metals, which may be greater than 0, greater than or equal to 0.0001, or greater than or equal to 0.0002, and may also be less than or equal to 0.0005, or less than or equal to 0.0004.

[0127] In the above chemical formula 3, y3 is the molar ratio of element A, which is oxygen-substituted in the first lithium transition metal complex 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.

[0128] The first positive active material is aluminum (Al), zirconium (Zr), and M 3It may comprise a first lithium transition metal composite oxide comprising. As a specific example, the first cathode active material comprises aluminum (Al), zirconium (Zr), and M 3 It may contain [element] as a doping element.

[0129] The above M 3 It may be a metallic element with an oxidation number of +4 or higher. As a specific example, the above M 3 It may be one or more selected from the group consisting of titanium (Ti), tantalum (Ta), tungsten (W), vanadium (V), molybdenum (Mo), and niobium (Nb).

[0130] The aluminum (Al) may be included in an amount of 500 ppm to 3,000 ppm with respect to the total weight of the first lithium transition metal composite oxide. As a specific example, the aluminum (Al) may be included in an amount of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more with respect to the total weight of the first lithium transition metal composite oxide, and may also be included in an amount of 3,000 ppm or less, 2,500 ppm or less, or 2,000 ppm or less. The zirconium (Zr) may be included in an amount of 500 ppm to 3,000 ppm with respect to the total weight of the first lithium transition metal composite oxide. As a specific example, the zirconium (Zr) may be included in an amount of 500 ppm or more, 1,000 ppm or more, or 1,500 ppm or more with respect to the total weight of the first lithium transition metal composite oxide, and may also be included in an amount of 3,000 ppm or less, 2,500 ppm or less, or 2,000 ppm or less. The M 3 It may be included in an amount of 100 ppm to 2,000 ppm with respect to the total weight of the first lithium transition metal complex oxide. As a specific example, the M 3The above may be included in an amount of 100 ppm or more, 200 ppm or more, 300 ppm or more, 400 ppm or more, or 500 ppm or more with respect to the total weight of the first lithium transition metal composite oxide, and may also be included in an amount 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.

[0131] The first positive active material comprises a coating portion formed on at least one of a primary particle surface, a primary particle interface, and a secondary particle surface, and the coating portion may comprise one or more coating elements selected from the group consisting of cobalt (Co), aluminum (Al), and boron (B). The coating portion may be an island-type coating portion formed on a part of at least one of the primary particle surface, the primary particle interface, and the secondary particle surface. The coating portion may be a coating layer formed by surrounding at least one of the primary particle surface, the primary particle interface, and the secondary particle surface.

[0132] The above coating portion may include at least one of a coating portion containing cobalt (Co), a coating portion containing aluminum (Al), a coating portion containing boron (B), a coating portion containing cobalt (Co) and aluminum (Al), a coating portion containing cobalt (Co) and boron (B), a coating portion containing aluminum (Al) and boron (B), and a coating portion containing cobalt (Co), aluminum (Al), and boron (B).

[0133] The above coating portion may include a coating portion comprising cobalt (Co), a coating portion comprising cobalt (Co) and boron (B), and a coating portion comprising boron (B) formed sequentially. The above coating portion may include a cobalt-boron oxide.

[0134] The above coating portion may include a coating portion comprising cobalt (Co) and aluminum (Al), a coating portion comprising cobalt (Co), aluminum (Al) and boron (B), and a coating portion comprising boron (B) formed sequentially. The above coating portion may include a cobalt-aluminum-boron oxide.

[0135] When the above-mentioned first positive active material is fed into 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 rolled density calculated by Equation 3 below is 3.60 g / cm³ 3 It could be an abnormality.

[0136] [Equation 3]

[0137] Rolled density (g / cm³) 3 ) = Weight of positive active material (g) / Volume of pellet (cm³) 3 )

[0138] The first positive active material has a rolled density of 3.60 g / cm³ calculated by Equation 3. 3 It may be abnormal, and as a specific example, 3.61 g / cm³ 3 Above, 3.62 g / cm³ 3 Above, 3.63 g / cm³ 3 Above, 3.64 g / cm³ 3 Above, 3.65 g / cm³ 3 Above, 3.66 g / cm³ 3 Above, 3.67 g / cm³ 3 Above, 3.68 g / cm³ 3 Above, 3.69 g / cm³ 3 Above, 3.70 g / cm³ 3 Above, or 3.71 g / cm³ 3 It may be above, and although the upper limit is not specifically restricted, 10.0 g / cm³ 3 It may be less than or equal to

[0139] The first positive active material may be such that, for a lithium secondary battery comprising a positive electrode including the first positive active material; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte, the discharge capacity when the lithium secondary battery is discharged at a current of 1.0 C after being charged at a current of 0.5 C is 92.0% or more, based on the discharge capacity when the lithium secondary battery is discharged at a current of 0.1 C after being charged at a current of 0.5 C. Here, the lithium secondary battery is intended to verify the discharge capacity according to the output characteristics of the positive active material, and components other than the first positive active material are not particularly limited as long as they can be used in the lithium secondary battery. As a specific example, the first positive 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 discharged at a current of 0.1 C after being charged at a current of 0.5 C. The upper limit is not specifically restricted, but may be 100% or less.

[0140] The first positive active material may be such that, for a lithium secondary battery comprising a positive electrode including the first positive active material; a negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte, the discharge capacity when the lithium secondary battery is discharged at a current of 2.0 C after being charged at a current of 0.5 C is 89.0% or more, based on the discharge capacity when the lithium secondary battery is discharged at a current of 0.1 C after being charged at a current of 0.5 C. Here, the lithium secondary battery is intended to verify the discharge capacity according to the output characteristics of the positive active material, and components other than the first positive active material are not particularly limited as long as they can be used in the lithium secondary battery. As a specific example, the first positive 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, based on the discharge capacity when the lithium secondary battery is discharged at a current of 0.1 C after being charged at a current of 0.5 C.

[0141] The above-mentioned first cathode active material is a single-particle degree (Dv) corresponding to the diameter of the volume at the point where the cumulative volume distribution of the primary particles is 50%, when the volume value is calculated from Equation 4 below for each primary particle observed from an SEM image (measurement magnification 3,000x) of the surface of the secondary particles. 50 ) may be 1.2 µm or more and 3.8 µm or less.

[0142] [Equation 4]

[0143]

[0144] In the above Equation 4,

[0145] The radius is the radius of the surface of the primary particle when the surface of the primary particle observed from the SEM image (measurement magnification 3,000x) of the surface of the secondary particle is assumed to be circular.

[0146] As a specific example, the first positive active material is the degree of single particle size (Dv 50 ) may be 1.2 μm or more, 1.3 μm or more, 1.4 μm or more, 1.5 μm or more, 1.6 μm or more, or 1.65 μm or more, and may also be 3.8 μm or less, 3.7 μm or less, 3.6 μm or less, 3.59 μm or less, 3.58 μm or less, 3.57 μm or less, 3.56 μm or less, or 3.55 μm or less.

[0147]

[0148] Second positive active material

[0149] According to the present invention, the second positive active material comprises secondary particles aggregated from a plurality of primary particles, and the plurality of primary particles may have an average particle size of less than 1.0 μm as measured from an SEM image.

[0150] According to the present invention, the secondary particles are secondary particles formed by the aggregation of a plurality of primary particles, and specifically, they may be formed by the aggregation of 30 or more and 100,000 or fewer primary particles. Specifically, they may be formed by the aggregation of tens to thousands or tens to hundreds of primary particles. The second positive electrode active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer compared to the first positive electrode active material. 50 ) is small.

[0151] According to the present invention, the plurality of primary particles may have an average particle size of 0.1 μm or more as measured from an SEM image, and may also have an average particle size of less than 1.0 μm, 0.9 μm or less, 0.8 μm or less, 0.7 μm or less, 0.6 μm or less, or 0.5 μm or less. Here, when measuring the average particle size of the plurality of primary particles from an SEM image, the particle size of each primary particle may be a particle size based on the major axis of the primary particle.

[0152]

[0153] According to the present invention, the second positive electrode active material may comprise a second lithium transition metal composite oxide comprising nickel, cobalt, and manganese. As a specific example, the second positive electrode active material may comprise a second lithium transition metal composite oxide comprising 60 mol% or more of nickel among the total transition metals. The second lithium transition metal composite oxide may be a primary particle, a secondary particle, and the second positive electrode active material itself comprising these, and as a specific example, the second positive electrode active material may comprise a secondary particle formed by aggregating a plurality of primary particles composed of the second lithium transition metal composite oxide.

[0154] According to the present invention, the second positive electrode active material may comprise a second lithium transition metal complex oxide having a composition represented by the following chemical formula 2.

[0155] [Chemical Formula 2]

[0156] Li x2 Ni a2 Co b2 Mn c2 M 2 d2 O2

[0157] In the above chemical formula 2,

[0158] M 2is 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, where 0.9≤x2≤1.3, 0.6≤a2<1.0, 0 <b2<0.4, 0<c2<0.4, 0≤d2≤0.2, a2+b2+c2+d2=1이다.

[0159] In the above chemical formula 2, x2 is the molar ratio of lithium to the transition metal in the second lithium transition metal complex oxide, which 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.

[0160] In the above chemical formula 2, a2, b2, c2, and d2 are, respectively, nickel (Ni), cobalt (Co), manganese (Mn) among transition metals and a doping element (M 2It may be a mole fraction for ). As a specific example, the above a2 may be a mole fraction for nickel (Ni) among transition metals, which is 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.81 or more, 0.82 or more, 0.83 or more, and also less than 1.0, 0.99 or less, 0.98 or less, 0.97 or less, or 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.88 or less, 0.85 or less. Additionally, the above b2 may be a mole fraction of cobalt (Co) among the transition metals that is 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 c2 may be a mole fraction of manganese (Mn) among the transition metals that is 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 d2 is a doping element (M) among the transition metals 2As a mole fraction for ), it may be 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, and additionally, 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 It may be 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. When the composition of the second lithium transition metal composite oxide is adjusted as above, the capacity can be further improved.

[0161]

[0162] According to the present invention, the second positive active material has an average particle size (D) based on the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 ) may be 2.0 μm or more and 6.0 μm or less. That is, the second positive electrode active material may be a quenched secondary particle positive electrode active material. As a specific example, the second positive electrode active material has an average particle size (D 50) may be 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, 2.5 µm or more, 2.6 µm or more, 2.7 µm or more, 2.8 µm or more, 2.9 µm or more, 3.0 µm or more, 3.1 µm or more, 3.2 µm or more, 3.3 µm or more, 3.4 µm or more, 3.5 µm or more, 3.6 µm or more, 3.7 µm or more, 3.8 µm or more, 3.9 µm or more, 4.0 µm or more, 4.1 µm or more, 4.2 µm or more, 4.3 µm or more, 4.4 µm or more, or 4.5 µm or more, and may also be 6.0 µm or less, 5.9 µm or less, 5.8 µm or less, 5.7 It may be µm or less, 5.6 µm or less, 5.5 µm or less, 5.4 µm or less, 5.3 µm or less, 5.2 µm or less, 5.1 µm or less, or 5.0 µm or less. In this case, the second cathode active material is appropriately filled between the first cathode active materials so that the rolling density of the cathode material can be further improved, and as a result, the energy density and lifespan characteristics of the battery to which it is applied can be improved.

[0163]

[0164] The second positive electrode active material may comprise a second lithium transition metal composite oxide comprising one or more selected from the group consisting of aluminum (Al), zirconium (Zr), and titanium (Ti). As a specific example, the second positive electrode active material may comprise aluminum (Al) and zirconium (Zr) as doping elements, or aluminum (Al) and titanium (Ti) as doping elements.

[0165] The aluminum (Al) may be included in an amount of 4,000 ppm to 7,000 ppm with respect to the total weight of the second lithium transition metal composite oxide. As a specific example, the aluminum (Al) may be included in an amount of 4,000 ppm or more, 4,500 ppm or more, or 5,000 ppm or more with respect to the total weight of the second lithium transition metal composite oxide, and may also be included in an amount of 7,000 ppm or less, 6,500 ppm or less, or 6,000 ppm or less. The zirconium (Zr) may be included in an amount of 1,500 ppm to 3,500 ppm with respect to the total weight of the second lithium transition metal composite oxide. As a specific example, the zirconium (Zr) may be included in an amount of 1,500 ppm or more, 2,000 ppm or more, or 2,500 ppm or more with respect to the total weight of the second lithium transition metal composite oxide, and may also be included in an amount of 3,500 ppm or less, 3,000 ppm or less, or 2,500 ppm or less. The titanium (Ti) may be included in an amount of 2,000 ppm to 4,000 ppm with respect to the total weight of the second lithium transition metal composite oxide. As a specific example, the titanium (Ti) may be included in an amount of 2,000 ppm or more, 2,500 ppm or more, or 3,000 ppm or more with respect to the total weight of the second lithium transition metal composite oxide, and may also be included in an amount of 4,000 ppm or less, 3,500 ppm or less, or 3,000 ppm or less.

[0166] The second positive active material comprises a coating portion formed on at least one of a primary particle surface, a primary particle interface, and a secondary particle surface, and the coating portion may include boron (B). The coating portion may be an island-type coating portion formed on a part of at least one of the primary particle surface, the primary particle interface, and the secondary particle surface. The coating portion may be a coating layer formed by covering at least one of the primary particle surface, the primary particle interface, and the secondary particle surface.

[0167]

[0168] Method for manufacturing cathode material

[0169] According to the present invention, the cathode material can be prepared by mixing the first cathode active material and the second cathode active material. The mixing can be performed by conventional methods used in the industry for mixing two or more materials, for example, using an acoustic mixer.

[0170]

[0171] The manufacturing method of each positive electrode active material is described in detail below.

[0172]

[0173] Method for manufacturing the first positive active material

[0174] The above-mentioned first positive active material may be manufactured by the following manufacturing method, but is not limited thereto.

[0175]

[0176] According to one embodiment of the present invention, the method for manufacturing the first positive electrode active material may be carried out by including the step (S10) of mixing a first positive electrode active material precursor comprising nickel, cobalt, and manganese with a lithium raw material and performing calcination to manufacture a calcined product.

[0177] According to one embodiment of the present invention, the step (S10) may be performed by a method of performing firing by dividing the temperature range within a single firing step (one-step method), a method of performing firing by dividing the temperature range into two steps (two-step method), and a method of performing plasticity prior to performing firing by dividing the temperature range within a single firing step (plasticity method).

[0178] According to one embodiment of the present invention, the one-step method is a method of performing calcination in succession in two temperature ranges within a single calcination step, wherein a first-stage calcination is performed on a mixture of a first positive active material precursor and a lithium raw material, and immediately thereafter, a second-stage calcination is performed by changing the temperature range. At this time, the second-stage calcination can be performed at a lower temperature than the first-stage calcination, and each calcination temperature can be controlled according to the nickel content, and through such temperature control, the shape and size of the primary particles and the average particle size of the secondary particles can be controlled.

[0179] According to one embodiment of the present invention, the two-step method is a method of performing a first calcination and a second calcination separately. A first calcination is performed on a mixture of a first positive active material precursor and a lithium raw material, and a first calcined product produced by the first calcination is crushed, and then the crushed product is subjected to a second calcination. At this time, the second calcination can be performed at a lower temperature than the first calcination, and each calcination temperature can be controlled according to the nickel content. Through such temperature control, the shape and size of the first particles and the average particle size of the second particles can be controlled.

[0180] According to one embodiment of the present invention, the plasticization method is a method of performing plasticization prior to one-step firing, wherein plasticization is performed on a mixture of a first positive active material precursor and a lithium raw material, and a one-step method is performed on the plasticized product. At this time, the plasticization can be performed at a lower temperature than that of one-step firing, and each firing temperature can be controlled according to the nickel content, and through such temperature control, the shape and size of the primary particles and the average particle size of the secondary particles can be controlled.

[0181] According to one embodiment of the present invention, the first positive active material precursor may contain 60 mol% or more of nickel among the transition metals. As a specific example, the first positive active material precursor may be a transition metal hydroxide comprising nickel, cobalt, and manganese, and containing 60 mol% or more of nickel among the transition metals. As a specific example, the transition metal hydroxide may have an average composition represented by the following chemical formula 4.

[0182] [Chemical Formula 4]

[0183] Ni a4 Co b4 Mn c4 (OH)2

[0184] In the above chemical formula 4, 0.6 ≤ a4 < 1.0, 0 <b4<0.4, 0<c4<0.4, a4+b4+c4=1이다.

[0185] According to one embodiment of the present invention, in the above formula 4, a4, b4, and c4 may each be a mole fraction for nickel (Ni), cobalt (Co), and manganese (Mn) among the transition metals. As a specific example, a4 may be a mole fraction for nickel (Ni) among the transition metals of 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. In addition, the above b4 may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more as a mole fraction for cobalt (Co) among transition metals, 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 as a mole fraction for manganese (Mn) among transition metals, and may be greater than 0, 0.01 or more, or 0.05 or more as a mole fraction, 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 as a mole fraction for manganese (Mn) among transition metals.

[0186] 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, and for example, Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, Li3C6H5O7, or a mixture thereof may be used.

[0187] According to one embodiment of the present invention, step (S10) may be performed by further including 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 said elements, and specific examples include Al2O3, Al(OH)3, Al(NO3)3·9H2O, Al2(SO4)3, Y2O3, It could be ZrO2, etc.

[0188] According to one embodiment of the present invention, the doping material may include Al, Y, and Zr. Additionally, the doping material may include Al, Zr, and a metal element (M) having an oxidation state of +4 or higher. 3 It may include ).

[0189] According to one embodiment of the present invention, when mixing the first positive active material precursor and the lithium raw material in step (S10), the molar ratio (Li / M) of lithium (Li) of the lithium raw material to the transition metal (M) of the first positive active material precursor may be 0.9 or higher and 1.3 or lower. As a specific example, the Li / M may be 0.9 or higher, 0.95 or higher, or 1.0 or higher, and may also be 1.1 or lower, 1.07 or lower, 1.05 or lower, or 1.04 or lower, and the Li / M may be adjusted according to the nickel content in the transition metal.

[0190] According to one embodiment of the present invention, the method for manufacturing the first positive active material may further include a step (S20) of coating the first positive active material manufactured in step (S10). As a specific example, step (S20) may be performed by including one or more coating raw materials selected from the group consisting of Co and B. Additionally, step (S20) may be performed by further including an Al coating raw material.

[0191] According to one embodiment of the present invention, the coating in step (S20) may be performed by coating each coating raw material simultaneously, or by performing them sequentially. As a specific example, the coating in step (S20) may be performed by including a step (S21) of mixing a Co coating raw material with a first positive active material and heat treating it, and a step (S22) of mixing a B coating raw material with a coating product prepared in step (S21) and heat treating it. As another specific example, the coating in step (S20) may be performed by including a step (S21) of mixing a Co coating raw material and an Al coating raw material with a first positive active material and heat treating it, and a step (S22) of mixing a B coating raw material with a coating product prepared in step (S21) and heat treating it.

[0192] 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.

[0193] According to one embodiment of the present invention, the method for manufacturing the first positive electrode active material may include, when carrying out steps (S10) and (S20), a step of crushing or sieving the calcined product as needed after calcination, and the crushing may be carried out without particular limitation using any crushing device capable of crushing the first positive electrode active material.

[0194] According to one embodiment of the present invention, the doping raw material and the coating raw material can be introduced by adjusting them to satisfy the doping element content and coating element content of the first cathode active material described above.

[0195]

[0196] Method for manufacturing a second positive active material

[0197] The above second positive active material may be manufactured by the following manufacturing method, but is not limited thereto.

[0198]

[0199] According to one embodiment of the present invention, the method for manufacturing the second positive electrode active material may be carried out by including the step (S10') of mixing a second positive electrode active material precursor comprising nickel, cobalt, and manganese with a lithium raw material and performing calcination to manufacture a calcined product. At this time, the calcination temperature may be lower than the calcination temperature in the method for manufacturing the first positive electrode active material.

[0200] According to one embodiment of the present invention, the step (S10') may be performed by a method of performing firing only once, a method of performing firing by dividing the temperature range within a single firing step (one-step method), etc.

[0201] According to one embodiment of the present invention, the one-step method is a method of performing calcination in succession in two temperature ranges within a single calcination step, wherein a first-stage calcination is performed on a mixture of a second positive active material precursor and a lithium raw material, and immediately thereafter, a second-stage calcination is performed by changing the temperature range. At this time, each calcination temperature can be controlled according to the nickel content, and through such temperature control, the shape and size of the primary particles and the average particle size of the secondary particles can be controlled.

[0202] According to one embodiment of the present invention, the second positive active material precursor may contain 60 mol% or more of nickel among the transition metals. As a specific example, the second positive active material precursor may be a transition metal hydroxide comprising nickel, cobalt, and manganese, and containing 60 mol% or more of nickel among the transition metals. As a specific example, the transition metal hydroxide may have an average composition represented by the following chemical formula 5.

[0203] [Chemical Formula 5]

[0204] Ni a5 Co b5 Mn c5 (OH)2

[0205] In the above chemical formula 5, 0.6 ≤ a5 < 1.0, 0 <b5<0.4, 0<c5<0.4, a5+b5+c5=1이다.

[0206] According to one embodiment of the present invention, in the above formula 5, a5, b5, and c5 may each be a mole fraction for nickel (Ni), cobalt (Co), and manganese (Mn) among the transition metals. As a specific example, a5 may be a mole fraction for nickel (Ni) among the transition metals of 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. In addition, the above b5 may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more as a mole fraction for cobalt (Co) among transition metals, 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 as a mole fraction for manganese (Mn) among transition metals, and may be greater than 0, 0.01 or more, or 0.05 or more as a mole fraction, 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.

[0207] 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, and for example, Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, Li3C6H5O7, or a mixture thereof may be used.

[0208] According to one embodiment of the present invention, the step (S10') may be carried out by further including 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 said elements, and specific examples include Al2O3, Al(OH)3, Al(NO3)3·9H2O, Al2(SO4)3, Y2O3, It could be ZrO2, TiO2, etc.

[0209] According to one embodiment of the present invention, the doping raw material may include Al and further include one or more selected from the group consisting of Zr and Ti.

[0210] According to one embodiment of the present invention, when mixing the second positive active material precursor and the lithium raw material in step (S10'), the molar ratio (Li / M) of lithium (Li) of the lithium raw material to the transition metal (M) of the second positive active material precursor may be 0.9 or higher and 1.3 or lower. As a specific example, the Li / M may be 0.9 or higher, 0.95 or higher, or 1.0 or higher, and may also be 1.1 or lower, 1.07 or lower, or 1.06 or lower, and the Li / M may be adjusted according to the nickel content in the transition metal.

[0211] According to one embodiment of the present invention, the method for manufacturing the second positive active material may further include a step (S20') of coating the second positive active material manufactured in step (S10'). As a specific example, step (S20') may be performed by including a B coating raw material.

[0212] As a specific example, the coating of the above step (S20') may be carried out by including the step (S21') of mixing a B coating raw material with the second positive active material and heat treating it.

[0213] According to one embodiment of the present invention, the B coating raw material may be H3BO3.

[0214] According to one embodiment of the present invention, the method for manufacturing the second positive electrode active material may include, when carrying out steps (S10') and (S20'), a step of crushing or sieving the calcined product as needed after calcination, and the crushing may be carried out without particular limitation using any crushing device capable of crushing the second positive electrode active material.

[0215] According to one embodiment of the present invention, the doping raw material and the coating raw material can be introduced by adjusting them to satisfy the doping element content and coating element content of the second positive active material described above.

[0216]

[0217] anode

[0218] The present invention provides an anode comprising the above anode material.

[0219] The above positive electrode may include 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 material.

[0220] The above positive current collector may include a highly conductive metal, and is not particularly limited as long as it facilitates the adhesion of the positive active material layer and is non-reactive within the voltage range of the battery. The above positive current collector may be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. Additionally, the above positive current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to increase the adhesion of the positive material. It may be used in various forms, such as films, sheets, foils, nets, porous bodies, foams, and nonwoven fabrics.

[0221] The above positive active material layer may include, together with the positive material, a conductive material and a binder as needed. In this case, the positive material may be included in an amount of 80% to 99% by weight, more specifically 85% to 98.5% by weight, based on the total weight of the positive active material layer, and may exhibit excellent capacity characteristics within this range.

[0222] The above conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. 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 fibers; metal powder 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 alone or a mixture of two or more may be used. The above 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.

[0223] The above binder serves to improve adhesion between the cathode material particles and adhesion between the cathode 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 hydrogens thereof are substituted with Li, Na, or Ca, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. The above binder may be included in an amount of 0.1% to 15% by weight relative to the total weight of the positive active material layer.

[0224] The above-described anode may be manufactured according to a conventional anode manufacturing method, except for using the above-described anode material. Specifically, the above-described anode may be manufactured by applying a composition for forming an anode active material layer, prepared by dissolving or dispersing the above-described anode material and, optionally, a binder, a conductive material, and a dispersant in a solvent, onto an anode current collector, followed by drying and rolling, or by casting the composition for forming an anode active material layer onto a separate support and then laminating the film obtained by peeling from the support onto an anode current collector.

[0225] The above solvent may be a solvent commonly used in the relevant technical field, and may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it is sufficient to dissolve or disperse the cathode material, conductive material, binder, and dispersant, taking into account the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that can exhibit excellent thickness uniformity when coated for cathode manufacturing thereafter.

[0226]

[0227] lithium secondary battery

[0228] The present invention provides a lithium secondary battery comprising the above positive electrode.

[0229] The above lithium secondary battery may comprise the positive electrode; the negative electrode; a separator interposed between the positive electrode and the negative electrode; and an electrolyte. Additionally, the lithium secondary battery may optionally further comprise a battery container housing an electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member sealing the battery container.

[0230] The above cathode may include a cathode current collector and a cathode active material layer located on the cathode current collector.

[0231] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative current collector may typically have a thickness of 3 μm to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0232] The above-mentioned cathode active material layer may optionally include a binder and a conductive material together with the cathode active material.

[0233] As the above-mentioned negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. 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; metal oxides capable of doping and dedoping lithium, such as SiOβ (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the above-mentioned metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the above-mentioned negative electrode active material. Furthermore, the carbon material may include both low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, 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 carbon such as petroleum or coal tar pitch-derived cokes. The above-mentioned cathode active material may be included in an amount of 80% to 99% by weight based on the total weight of the cathode active material layer.

[0234] The binder of the above-mentioned negative electrode active material layer is a component that assists in the bonding between the conductive material, the active material, and the current collector, and is typically 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.

[0235] The conductive material of the above-mentioned 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 is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; fluorinated carbon; metal powders such as aluminum or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0236] The above cathode may be manufactured by applying and drying a composition for forming a cathode active material layer, prepared by dissolving or dispersing a cathode active material and optionally a binder and a conductive material in a solvent, onto a cathode current collector, or by casting the composition for forming a cathode active material layer onto a separate support and then laminating the film obtained by peeling from the support onto a cathode current collector.

[0237] The above separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. It can be used without special limitations as long as it is typically used as a separator in a lithium secondary battery, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte wettability. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and it may optionally be used in a single-layer or multi-layer structure.

[0238] Examples of the above electrolytes include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used in the manufacture of lithium secondary batteries, but are not limited to these. As a specific example, the above electrolyte may include an organic solvent and a lithium salt.

[0239] The above-mentioned organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above-mentioned organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; and carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC). Alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond-directing ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, carbonate-based solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.

[0240] The above lithium salt may be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the anion of the above 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 at least one 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. It is preferable to use the lithium salt within the range of 0.1 M to 2.0 M. 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.

[0241] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, haloalkylene carbonate-based compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, 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 included in an amount of 0.1% to 5% by weight based on the total weight of the electrolyte.

[0242]

[0243] Since the lithium secondary battery comprising the cathode material according to the present invention stably exhibits excellent energy density, it is useful in fields such as portable devices like mobile phones, laptop computers, and digital cameras, and electric vehicles like hybrid electric vehicles (HEV) and electric vehicles (EV).

[0244] The external shape of the lithium secondary battery of the present invention is not particularly limited, but can be a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0245] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells.

[0246] Accordingly, a battery module including the above-mentioned lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0247] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0248]

[0249] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0250]

[0251] Preparation Example

[0252] Preparation Example 1

[0253] Ni as a secondary particle form formed by the aggregation of tens to hundreds of primary particles 0.965 Co 0.005 Mn 0.03 Transition metal complex hydroxide having a composition represented by (OH)2 (D 50 : 9.4 μm) and LiOH were mixed so that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.03. In addition, a mixture was prepared by adding and mixing Al(OH)3 at a content of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal complex hydroxide.

[0254] The above mixture was plasticized at 485°C for 5 hours under an oxygen atmosphere to obtain a plastic product. Afterwards, the plastic product was sieved through a 300-mesh sieve.

[0255] The above-mentioned sieved plastic product was fired in an oxygen atmosphere at 830 °C for 6 hours, followed by continuous firing at 760 °C for 12 hours to obtain a sintered product. The sintered product was ground at room temperature (using a fin mill grinding equipment (Retsch ZM100), performed under conditions of 8,000 rpm) to obtain an average particle size (D 50 ) is 10.2 μm, and LiNi 0.9577 Co 0.005 Mn 0.0298 Al 0.005 Y 0.001 Zr 0.0015 A lithium transition metal composite oxide having a composition represented by O2 and in the form of secondary particles with aggregated primary particles was prepared.

[0256] A mixture was prepared by adding Al(OH)3 at a content of 500 ppm relative to the total weight of the prepared secondary particle-shaped lithium transition metal composite oxide and uniformly mixing, such that the molar ratio of cobalt (Co) contained in Co(OH)2 to the metals excluding lithium (Ni+Co+Mn+Al+Y+Zr) contained in the lithium transition metal composite oxide (Co(OH)2) (Co / (Ni+Co+Mn+Al+Y+Zr)) is 0.025. The mixture was heat-treated under an oxygen atmosphere at 650 °C for 2 hours, continuously at 710 °C for 4 hours, and continuously at 500 °C for 3 hours to obtain a first coating product. At room temperature, the first coating product had an average particle size (D 50 A positive electrode active material was prepared by grinding the material to a size of 10.2 μm (using a fin mill grinding equipment (Retsch ZM100) at 6,000 rpm) to form a coating portion containing Co and Al on a lithium transition metal composite oxide in the form of secondary particles aggregated from primary particles. The overall composition of the positive electrode active material including the coating portion containing Co and Al is LiNi 0.9321 Co 0.0298 Mn 0.029 Al 0.0066 Y 0.001Zr 0.0015 It was O2.

[0257] A mixture was prepared by adding H3BO3 to the ground first coating product at a content of 500 ppm relative to the total weight of the ground first coating product and mixing. The mixture was heat-treated at 330 °C for 5 hours under an atmospheric conditions to obtain a second coating product. The second coating product was sieved through a 300-mesh sieve at room temperature to obtain an average particle size (D 50 A positive electrode active material was prepared in which a coating portion containing Co, Al, and B was formed on a lithium transition metal composite oxide in the form of secondary particles aggregated from primary particles, having a thickness of 10.2 μm. The overall composition of the positive electrode active material including the coating portion containing Co, Al, and B is LiNi 0.9279 Co 0.0297 Mn 0.0288 Al 0.0066 Y 0.001 Zr 0.0015 B 0.0045 It was O2.

[0258]

[0259] Preparation Example 2

[0260] Ni as a secondary particle form formed by the aggregation of tens to hundreds of primary particles 0.96 Co 0.03 Mn 0.01 Transition metal complex hydroxide having a composition represented by (OH)2 (D 50 : 3.1 μm) and LiOH were mixed so that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.03. In addition, Al(OH)3 was added at a content of 6,000 ppm and TiO2 at a content of 3,000 ppm relative to the total weight of the transition metal complex hydroxide, and mixed to prepare a mixture.

[0261] The above mixture was calcined under an oxygen atmosphere at 650 °C for 3.65 hours, and subsequently calcined at 695 °C for 7.3 hours to obtain a calcined product. The calcined product was ground at room temperature (using a fin mill grinding equipment (Retsch ZM100), performed under conditions of 14,000 rpm) to obtain an average particle size (D 50 ) is 3.5 μm, and LiNi 0.9355 Co 0.0292 Mn 0.0097 Al 0.0199 Ti 0.0057 A lithium transition metal composite oxide having a composition represented by O2 and in the form of secondary particles with aggregated primary particles was prepared.

[0262] A mixture was prepared by adding H3BO3 to the above-prepared lithium transition metal composite oxide in the form of secondary particles at a content of 700 ppm relative to the total weight of the lithium transition metal composite oxide and mixing. The mixture was heat-treated at 300 °C for 5 hours under an atmospheric conditions to obtain a coated product. The coated product was sieved through a 300-mesh sieve at room temperature to obtain an average particle size (D 50 A positive electrode active material was prepared in which a coating portion containing B was formed on a lithium transition metal composite oxide in the form of secondary particles aggregated from primary particles, having a thickness of 3.5 μm. The overall composition of the positive electrode active material including the coating portion containing B is LiNi 0.9296 Co 0.0291 Mn 0.0097 Al 0.0198 Ti 0.0056 B 0.0062 It was O2.

[0263]

[0264] Preparation Example 3

[0265] Ni as a secondary particle form formed by the aggregation of tens to hundreds of primary particles 0.94 Co 0.03 Mn 0.03 Transition metal complex hydroxide having a composition represented by (OH)2 (D 50: 10.2 μm) and LiOH were mixed so that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.06. In addition, a mixture was prepared by adding and mixing Al(OH)3 at a content of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal complex hydroxide.

[0266] The above mixture was calcined at 730 °C for 5 hours under an oxygen atmosphere to obtain a calcined product. The calcined product was ground at room temperature (using a fin mill grinding equipment (Retsch ZM100), performed under conditions of 6,000 rpm) to obtain an average particle size (D 50 ) is 10.2 μm, and LiNi 0.9329 Co 0.0298 Mn 0.0298 Al 0.0050 Y 0.0010 Zr 0.0015 A lithium transition metal composite oxide in the form of secondary particles with aggregated primary particles was prepared having a composition represented by O2. Subsequently, 100 parts by weight of the prepared lithium transition metal composite oxide in the form of secondary particles and 100 parts by weight of water were stirred at a speed of 300 rpm for 5 minutes, and then washed using a filter press. The washed product was dried at 130 ℃ for 4 hours to prepare a dried product.

[0267] A mixture was prepared by adding H3BO3 to the above-prepared dried product at a content of 500 ppm relative to the total weight of the pulverized lithium transition metal complex oxide and mixing. The mixture was heat-treated at 330 °C for 5 hours under an atmospheric conditions to obtain a coated product. The coated product was sieved through a 300-mesh sieve at room temperature to obtain an average particle size (D 50 A positive electrode active material was prepared in which a coating portion containing B was formed on a lithium transition metal composite oxide in the form of secondary particles aggregated from primary particles, having a thickness of 10.2 μm. The overall composition of the positive electrode active material including the coating portion containing B is LiNi0.9287 Co 0.0296 Mn 0.0296 Al 0.005 Y 0.0010 Zr 0.0015 B 0.0045 It was O2.

[0268]

[0269] Preparation Example 4

[0270] Ni as a secondary particle form formed by the aggregation of tens to hundreds of primary particles 0.96 Co 0.03 Mn 0.01 Transition metal complex hydroxide having a composition represented by (OH)2 (D 50 : 3.5 μm) and LiOH were mixed so that the molar ratio of lithium (Li) to transition metal (Ni+Co+Mn) (Li / (Ni+Co+Mn)) was 1.02. In addition, a mixture was prepared by adding and mixing Al(OH)3 at a content of 1,470 ppm, Y2O3 at 1,000 ppm, and ZrO2 at 1,500 ppm relative to the total weight of the transition metal complex hydroxide.

[0271] The above mixture was calcined under an oxygen atmosphere at 830 °C for 6 hours, followed by continuous calcination at 760 °C for 9 hours to obtain a calcined product. The calcined product was ground at room temperature (using a fin mill grinding equipment (Retsch ZM100), performed under conditions of 8,000 rpm) to obtain an average particle size (D 50 ) is 4.2 μm, and LiNi 0.9528 Co 0.0298 Mn 0.0099 Al 0.005 Y 0.001 Zr 0.0015 A lithium transition metal composite oxide was prepared having a composition represented by O2, in the form of a single particle or a secondary particle in which two or more and ten or fewer primary particles are aggregated.

[0272] A mixture was prepared by uniformly mixing the lithium transition metal composite oxide prepared above in the form of single particles or secondary particles aggregated from two or more to ten or fewer primary particles, and Al(OH)3 at a content of 500 ppm relative to the total weight of the prepared lithium transition metal composite oxide prepared above in the form of single particles or secondary particles aggregated from two or more to ten or fewer primary particles, such that the molar ratio of cobalt (Co) contained in Co(OH)2 to the metals excluding lithium (Ni+Co+Mn+Al+Y+Zr) contained in the lithium transition metal composite oxide (Co / (Ni+Co+Mn+Al+Y+Zr)) is 0.02. The mixture was heat-treated under an oxygen atmosphere at 700 °C for 3 hours, followed by heat treatment at 500 °C for 3 hours to obtain a first coating product. At room temperature, the first coating product had an average particle size (D 50 A positive electrode active material was prepared by grinding the material to a size of 4.2 μm (using a fin mill grinding equipment (Retsch ZM100) under conditions of 6,000 rpm) to form a single particle or a secondary particle in which two or more and ten or fewer primary particles are aggregated, thereby forming a coating portion containing Co and Al on the lithium transition metal composite oxide. The overall composition of the positive electrode active material including the coating portion containing Co and Al is LiNi 0.932 Co 0.0491 Mn 0.0097 Al 0.0067 Y 0.001 Zr 0.0015 It was O2.

[0273]

[0274] Examples and Comparative Examples

[0275] Example 1

[0276] The cathode active material prepared in Preparation Example 1 and the cathode active material prepared in Preparation Example 2 were mixed in a weight ratio of 2:8 using an acoustic mixer to prepare a cathode material.

[0277]

[0278] Example 2

[0279] The cathode active material prepared in Preparation Example 1 and the cathode active material prepared in Preparation Example 2 were mixed in a weight ratio of 5:5 using an acoustic mixer to prepare a cathode material.

[0280]

[0281] Example 3

[0282] The cathode active material prepared in Preparation Example 1 and the cathode active material prepared in Preparation Example 2 were mixed in a weight ratio of 8:2 using an acoustic mixer to prepare a cathode material.

[0283]

[0284] Comparative Example 1

[0285] The cathode active material prepared in Preparation Example 2 was used as the cathode material in Comparative Example 1.

[0286]

[0287] Comparative Example 2

[0288] The cathode active material prepared in Preparation Example 1 was used as the cathode material in Comparative Example 2.

[0289]

[0290] Comparative Example 3

[0291] The cathode active material prepared in Preparation Example 3 and the cathode active material prepared in Preparation Example 4 were mixed in a weight ratio of 5:5 using an acoustic mixer to prepare a cathode material.

[0292]

[0293] Experimental Example

[0294] Experimental Example 1: Particle Analysis

[0295] The cathode active materials prepared in Preparation Examples 1 to 4 were photographed using a scanning electron microscope (FEI, quanta250 FEG) and are shown in FIG. 1 (Preparation Example 1), FIG. 2 (Preparation Example 2), FIG. 3 (Preparation Example 3), and FIG. 4 (Preparation Example 4). The average particle size of the primary particles measured from the SEM images is shown in Table 1 below. In this case, the particle size of the primary particles is the particle size based on the major axis of the primary particles.

[0296]

[0297] Average particle size of primary particles measured from SEM images (㎛) Preparation Example 11.7 Preparation Example 20.5 Preparation Example 30.9 Preparation Example 42.3

[0298] Then, the positive electrode active material prepared in Preparation Example 1 was ion-milled, photographed using a scanning electron microscope, and the result is shown in Fig. 5.

[0299] Referring to FIG. 5, the cathode active material of Preparation Example 1 comprises secondary particles aggregated from a plurality of primary particles, and it can be confirmed that 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. Additionally, it can be confirmed that the plurality of primary particles include three or more disk-type primary particles. In this case, the disk-type primary particles refer to primary particles observed from an SEM image of the surface or cross-section of the secondary particles, wherein, for the primary particles existing within an angle of 45° or less relative to the major axis direction, a virtual tangent line having the most contact points is drawn for each of the two boundary lines of the primary particles, and a single virtual line crossing the two tangent lines is drawn, and the internal angle on the same side is 150° or more and 210° or less. For reference, in FIG. 5, when a virtual yellow tangent line with the most points of contact is drawn for each of the two boundary lines of a primary particle existing within an angle of 45° or less based on the red major axis direction, a single virtual line (not shown) crossing the two yellow tangent lines satisfies an internal angle of 150° or more and 210° or less, and a primary particle corresponding to this case is defined as a disk-shaped primary particle. Furthermore, it can be confirmed that the disk-shaped primary particle has a minor axis of 0.3 μm or more and an aspect ratio (major axis / minor axis) of 1.5 or more.

[0300]

[0301] In addition, a segmentation image showing a plurality of cathode active materials segmented by performing image analysis based on an artificial intelligence model from the SEM image of Manufacturing Example 1 of the present invention is shown in FIG. 6.

[0302]

[0303] Experimental Example 2: Measurement of Rolled Density

[0304] Using an automatic pellet press (Auto Pellet Press, Carver, 3887.4), a cylindrical mold was used to adjust the zero point for thickness on a circular pellet holder having a diameter of 13 mm. Subsequently, 3 g each of the cathode materials prepared in Examples 1 to 3 and Comparative Examples 1 to 3 were placed in the circular pellet holder, and the thickness of the formed pellet was measured by applying a force until it reached 9,000 kgf. Then, the pellet volume was calculated using Equation 5 below, and the rolling density was calculated using Equation 3 below, and the results are shown in Table 2 below.

[0305] In addition, FIG. 7 shows the rolling densities of Comparative Example 1, Example 1, Example 2, Example 3, and Comparative Example 2 according to the mixing ratio (measured values ​​for Ni > 90), and additionally, the rolling densities predicted according to the mixing ratio from the rolling densities of Comparative Example 1 and Comparative Example 2 are shown as dashed lines (predicted values ​​for Ni > 90). For reference, in FIG. 7, the blending ratio is the weight ratio of the first positive active material to the total weight of the first positive active material and the second positive active material.

[0306] [Equation 5]

[0307] Pellet volume (cm²) 3 ) = π(radius of the circular pellet holder (cm)) 2 × Pellet thickness (cm)

[0308] [Equation 3]

[0309] Rolled density (g / cm³) 3 ) = Weight of positive active material (g) / Volume of pellet (cm³) 3 )

[0310]

[0311] Experimental Example 3: Preparation and Evaluation of Coin-Type Half-Batteries

[0312] An anode slurry was prepared by mixing 95 parts by weight of each anode material prepared in Examples 1 to 3 and Comparative Examples 1 to 3, 2 parts by weight of a conductive material (Denka, FX35), and 3 parts by weight of a binder (KUREHA, KF9709) in an N-methylpyrrolidone (NMP) solvent. The prepared anode slurry was applied to one side of an aluminum current collector with a thickness of 20 μm, and an anode was prepared by rolling the anode active material layer to a porosity of 24 volume%.

[0313] An electrode assembly was manufactured by using a lithium metal electrode as the negative electrode and interposing a porous polyethylene separator between the positive and negative electrodes. This was placed inside a battery case and an electrolyte was injected to manufacture a coin-type half-cell. At this time, the electrolyte was prepared by dissolving 1M LiPF6 in an organic solvent mixed with ethylene carbonate (EC):ethyl methyl carbonate (EMC):dimethyl carbonate (DMC) in a volume ratio of 3:3:4.

[0314] Using the coin-type half-cell manufactured above, charging was performed in CC / CV mode at 25°C with a constant current of 0.1 C to 4.25 V (termination current 0.05 C), and then discharging was performed in CC mode until it reached 2.5 V, at which point the discharge capacity was measured and is shown in Table 2 below. At this time, 1 C was set to 200 mA / g.

[0315] Using the coin-type half-cell manufactured above, charging was performed in CC / CV mode at 45°C with a constant current of 0.5 C to 4.25 V (termination current 0.05 C), and then discharging was performed in CC mode with a constant current of 1.0 C until it reached 2.5 V, while measuring the discharge capacity and average voltage, which are shown in Table 2 below. In addition, the energy density per unit volume of the cell (= discharge capacity × average voltage × rolling density) was calculated and is shown in Table 2 below.

[0316] In addition, FIG. 8 shows the energy density per unit volume of the batteries of Comparative Example 1, Example 1, Example 2, Example 3, and Comparative Example 2 according to the mixing ratio (measured value for Ni > 90), and additionally, the energy density per unit volume of the batteries predicted according to the mixing ratio from the energy density per unit volume of Comparative Example 1 and Comparative Example 2 is shown as a dotted line (predicted value for Ni > 90). For reference, in FIG. 8, the blending ratio is the weight ratio of the first positive active material to the total weight of the first positive active material and the second positive active material.

[0317] Separately rolled density (g / cm³) 3 Discharge Capacity (mAh / g) Average Voltage (V) Energy Density (Wh / L) Example 1 3.5 22 27.7 3.8 0 130 46.0 Example 2 3.6 12 22 2.0 3.8 19 30 60.3 Example 3 3.6 21 7.3 3.8 40 30 0 3.9 Comparative Example 1 3.1 0 23 0.8 3.7 8 8 27 0 9.7 Comparative Example 2 3.5 6 21 7.0 3.8 5 329 8 4.0 Comparative Example 3 3.3 5 21 3.5 3.8 5 729 5 1.9

[0318] Referring to Table 2 and Figure 7 above, it can be seen that the rolling density of the cathode materials of Examples 1 to 3 is significantly higher than the rolling density expected from the rolling density of each of the cathode materials of Comparative Examples 1 and 2.

[0319] And, referring to Table 2 and Figure 8 above, it can be seen that the energy density of the battery containing the cathode materials of Examples 1 to 3 is significantly higher than the energy density expected from the energy density of each battery containing the cathode materials of Comparative Examples 1 and 2.

[0320] In addition, it can be confirmed that the cathode materials of Examples 1 to 3 have a higher rolling density compared to the cathode material of Comparative Example 3, which includes conventional quenched single particles and quenched secondary particles, and that both the capacity characteristics and energy density of the battery containing the cathode material are excellent. In conclusion, it can be seen that the cathode material according to the present invention not only has a high rolling density but can also improve the energy density of the electrode and battery containing it.

Claims

1. A first positive active material comprising secondary particles aggregated from 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 A cathode material comprising: a second cathode active material comprising a plurality of primary particles aggregated into secondary particles, wherein the plurality of primary particles have an average particle size of less than 1.0 μm 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; The first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer, compared to the second positive active material. 50 ) is a big thing, The plurality of primary particles of the first positive active material include disk-type primary particles, and The above-mentioned disc-shaped primary particle is a cathode material in which, regarding the primary particle observed from an SEM image of the surface or cross-section of the secondary particle, when a virtual tangent line having the most contact points is drawn for each of the two boundary lines of the primary particle existing within an angle of 45° or less with respect to the major axis direction, and a virtual line crossing the two tangent lines is drawn, the internal angle on the same side is 150° or more and 210° or less, the minor diameter is 0.3 μm or more, and the aspect ratio (major axis / minor diameter) is 1.5 or more.

2. In Claim 1, The above-mentioned first positive active material is a positive material comprising 10% or more and 90% or less by weight relative to the total weight of the first positive active material and the second positive active material.

3. In Claim 1, The above-mentioned disk-shaped primary particle is an anode material having a short diameter of 0.7 μm or more.

4. In Claim 1, The above-mentioned first positive active material is a positive material comprising a first lithium transition metal composite oxide containing 60 mol% or more of nickel among the total transition metals.

5. In Claim 4, The above-mentioned first lithium transition metal composite oxide is a cathode material having a composition represented by the following chemical formula 1: [Chemical Formula 1] Li x1 Ni a1 Co b1 Mr c1 M 1 d1 O2 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, and 0.9≤x1≤1.3, 0.6≤a1<1.0, 0 <b1<0.4, 0<c1<0.4, 0≤d1≤0.2, a1+b1+c1+d1=1이다.

6. In Claim 1, The above-mentioned second positive active material is a positive material comprising a second lithium transition metal composite oxide containing 60 mol% or more of nickel among the total transition metals.

7. In Claim 6, The above-mentioned second lithium transition metal composite oxide is a cathode material having a composition represented by the following chemical formula 2: [Chemical Formula 2] Li x2 Ni a2 Co b2 Mr c2 M 2 d2 O2 In the above chemical formula 2, M 2 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≤x2≤1.3, 0.6≤a2<1.0, 0 <b2<0.4, 0<c2<0.4, 0≤d2≤0.2, a2+b2+c2+d2=1이다.

8. In Claim 1, A cathode material in which the plurality of primary particles of the first cathode active material include single-crystal primary particles.

9. In Claim 1, The above-mentioned first positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 A cathode material having a thickness of 7.0 μm or more and 20.0 μm or less.

10. In Claim 1, The above second positive active material has an average particle size (D) according to the volume cumulative distribution measured using a laser diffraction particle size analyzer. 50 A cathode material having a thickness of 2.0 μm or more and 6.0 μm or less.

11. An anode comprising an anode material according to any one of claims 1 to 10.

12. A lithium secondary battery comprising a positive electrode according to claim 11; a negative electrode; a separator interposed between the positive electrode and the negative electrode and an electrolyte.

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