Positive electrode material and method for manufacturing same

Abstract

The positive electrode material of the present invention includes a first positive electrode active material and a second positive electrode active material. Each positive electrode active material includes a lithium transition metal composite oxide including 60 mol% or more of nickel, and includes a boron coating portion formed on the surface of the lithium transition metal composite oxide. By including a positive electrode active material in which the B / Ni ratio of the surface is appropriately controlled according to the average particle diameter of the positive electrode active material, an increase in the viscosity of a slurry manufactured by subsequent processes is reduced.

Description

Cathode material and method for manufacturing the same

[0001] [Cross-reference with related applications]

[0002] This application claims the benefit of priority to Korean Patent Application No. 2023-0150225, filed November 2, 2023, the entire disclosure of which is incorporated herein by reference.

[0003]

[0004] [Technical Field]

[0005] The present invention relates to a cathode material and a method for manufacturing the same.

[0006] Recently, with the advancement of technology such as electric vehicles, the demand for high-capacity secondary batteries is increasing, and accordingly, research on cathodes using high-nickel (High Ni) cathode active materials with excellent capacity characteristics is being actively conducted.

[0007] High-nickel cathode active materials are attracting attention for the development of high-energy-density cells due to their high capacity expression. However, as the nickel content increases, thermodynamic instability causes significant changes over time due to exposure to the atmosphere. In addition, when a slurry is made with high-nickel cathode materials, the viscosity gradually increases and gelation occurs after a certain period of time.

[0008] To address this issue, a method has been proposed to modify the surface of a high-nickel cathode active material by coating it with boron. While this method can mitigate some of the effects of aging and viscosity increase, the formation of a Li-Bo solid solution during the surface coating process can alter the electrical, ionic, and thermal conductivity of the cathode active material.

[0009] [Prior Art Literature]

[0010] [Patent Document]

[0011] (Patent Document 0001) JP 6862503 B2

[0012] The problem to be solved by the present invention is to provide a cathode material in which gel formation is reduced by controlling an appropriate B / Ni ratio according to the average particle size of the cathode active material.

[0013] Another problem to be solved by the present invention is to provide a method for manufacturing a cathode material in which the increase in slurry viscosity is reduced by appropriately controlling the B / Ni ratio according to the average particle size of the cathode active material.

[0014] (1) The present invention comprises at least one of a first positive electrode active material and a second positive electrode active material, wherein each of the first positive electrode active material and the second positive electrode active material comprises a lithium transition metal composite oxide containing nickel at 60 mol% or more based on the total transition metal; and a boron coating formed on the surface of the lithium transition metal composite oxide, wherein the first positive electrode active material is D 50 The first positive electrode active material is 2㎛ or more and 9㎛ or less, and the molar ratio of boron to nickel existing in the region from the outermost part to the center of 10nm is 3 or more and 8 or less, and the second positive electrode active material is D 50 A cathode material is provided, which is 10 ㎛ or more and 200 ㎛ or less, and has a molar ratio of boron to nickel in a region from the outermost part of the second cathode active material to 10 nm in the center direction of 9 or more and 45 or less.

[0015] (2) The present invention provides a cathode material in the above (1), wherein the lithium transition metal composite oxide has an average composition represented by the following chemical formula 1.

[0016] [Chemical Formula 1]

[0017] Li x Ni a Co b Mn c M d O2

[0018] In the above chemical formula 1,

[0019] M1 is at least one selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P and S, 0.8≤x≤1.2, 0.6≤a<1, 0 <b<0.2, 0<c<0.2, 0≤d<0.1, a+b+c+d=1이다.

[0020] (3) The present invention provides a cathode material in which, in (1) or (2), the molar ratio of boron to nickel present in a region extending from the outermost portion of the first cathode active material to the center within 10 nm is 4 or more and 7 or less.

[0021] (4) The present invention provides a cathode material in which the molar ratio of boron to nickel existing in a region of 10 nm from the outermost portion of the second cathode active material toward the center is 9 or more and 40 or less, in any one of the above (1) to (3).

[0022] (5) The present invention, in any one of the above (1) to (4), D of the first positive electrode active material 50 A cathode material having a size of 3㎛ or more and 8㎛ or less is provided.

[0023] (6) The present invention, in any one of the above (1) to (5), D of the second positive electrode active material 50 A cathode material having a diameter of 10㎛ or more and 190㎛ or less is provided.

[0024] (7) The present invention provides a positive electrode material comprising both the first positive electrode active material and the second positive electrode active material in any one of the above (1) to (6).

[0025] (8) The present invention provides a cathode material in which the second cathode active material is included in an amount of 40 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the sum of the first cathode active material and the second cathode active material, in any one of the above (1) to (7).

[0026] (9) The present invention provides a cathode material in which the second cathode active material is included in an amount of 70 parts by weight or more and 80 parts by weight or less based on 100 parts by weight of the sum of the first cathode active material and the second cathode active material, in any one of the above (1) to (8).

[0027] (10) The present invention provides a cathode comprising any one of the cathode materials (1) to (9).

[0028] (11) The present invention provides a lithium secondary battery including the positive electrode of (10).

[0029] According to one embodiment of the present invention, the cathode material has an appropriate B / Ni ratio controlled according to the average particle size of the cathode active material, thereby reducing gel formation.

[0030] According to one embodiment of the present invention, a method for manufacturing a cathode material appropriately controls the B / Ni ratio according to the average particle size of the cathode active material, thereby reducing an increase in slurry viscosity.

[0031] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0032]

[0033] In this specification, it should be understood that the terms “include,” “comprising,” or “having” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0034]

[0035] In this specification, the average particle diameter (D 50) means the particle size based on 50% of the volume cumulative particle size distribution of the positive electrode active material precursor, positive electrode active material or lithium transition metal oxide powder. The average particle diameter (D 50 ) can be measured using a laser diffraction method. For example, after dispersing the positive electrode active material powder in a dispersion medium, it can be measured by introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac MT 3000), irradiating it with ultrasonic waves of about 28 kHz at an output of 60 W, obtaining a volume cumulative particle size distribution graph, and then finding the particle size corresponding to 50% of the volume cumulative amount.

[0036]

[0037] Hereinafter, the present invention will be described in detail.

[0038]

[0039] <Polar electrode>

[0040] The present invention provides a cathode material.

[0041] According to one embodiment of the present invention, a cathode material comprises at least one of a first cathode active material and a second cathode active material, wherein each of the first cathode active material and the second cathode active material comprises a lithium transition metal composite oxide containing nickel at 60 mol% or more based on the total transition metal; and a boron coating formed on the surface of the lithium transition metal composite oxide, wherein the first cathode active material comprises D 50 The first positive electrode active material is 2㎛ or more and 9㎛ or less, and the molar ratio of boron to nickel existing in the region from the outermost part to the center of 10nm is 3 or more and 8 or less, and the second positive electrode active material is D 50 The second positive electrode active material has a diameter of 10 ㎛ or more and 20 ㎛ or less, and the molar ratio of boron to nickel present in a region extending from the outermost portion of the second positive electrode active material to the center of 10 nm is 9 or more and 45 or less.

[0042] The present inventors have found that by appropriately controlling the molar ratio of boron to nickel present in a region of up to 10 nm from the outermost to the center of each positive electrode active material according to the average particle size of each positive electrode active material including a boron coating portion, i.e., the B / Ni ratio of the surface, the content of the Li-BO solid solution included in each positive electrode active material manufactured can be adjusted to an appropriate level, and the increase in viscosity of the slurry can be alleviated to enable the slurry to be uniformly applied to the electrode, thereby reducing changes in electrical conductivity, ionic conductivity, and thermal conductivity resulting from the formation of the boron coating portion, thereby completing the present invention.

[0043]

[0044] Hereinafter, the first positive electrode active material and the second positive electrode active material included in the positive electrode material will be described.

[0045]

[0046] 1. First positive electrode active material

[0047] According to one embodiment of the present invention, a first positive electrode active material is a positive electrode active material comprising a lithium transition metal composite oxide containing nickel at 60 mol% or more with respect to the total transition metal; and a boron coating formed on the surface of the lithium transition metal composite oxide, wherein the average particle diameter of the first positive electrode active material is 2 μm or more and 9 μm or less, and the molar ratio of boron to nickel present on the surface of the first positive electrode active material may be 3 or more and 8 or less.

[0048]

[0049] According to one embodiment of the present invention, the average particle diameter of the first positive electrode active material is a small-diameter positive electrode active material of 2 µm or more and 9 µm or less, and as a specific example, the average particle diameter of the first positive electrode active material may be 2.2 µm or more, 2.4 µm or more, 2.6 µm or more, 2.8 µm or more, 3 µm or more, 3.2 µm or more, 3.4 µm or more, 3.6 µm or more, 3.8 µm or more, or 4 µm or more, and further, may be 8.8 µm or less, 8.6 µm or less, 8.4 µm or less, 8.2 µm or less, 8 µm or less, 7.8 µm or less, 7.6 µm or less, 7.4 µm or less, 7.2 µm or less, or 7 µm or less.

[0050]

[0051] According to one embodiment of the present invention, the boron coating portion may be formed on the surface of the first positive electrode active material and may include an ion-conductive lithium boron oxide (LBO) intermediate phase. A more detailed description of the Li-BO solid solution included in the boron coating portion will be provided below.

[0052] According to one embodiment of the present invention, the boron coating portion may be formed on the entire or a portion of the surface of the first positive electrode active material, and when the boron coating portion is formed on the entire surface of the first positive electrode active material, it may be referred to as a boron coating layer.

[0053] According to one embodiment of the present invention, the boron coating portion may occupy an area of ​​85% or more of the entire surface of the first positive electrode active material, and for specific examples, may occupy an area of ​​85.5% or more, 86% or more, 86.5% or more, 87% or more, or 87.5% or more.

[0054] According to one embodiment of the present invention, the boron coating portion may be a region of 5 nm or more and 100 nm or less in the center direction from the surface of the first positive electrode active material. Specifically, the boron coating portion may be a region of 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more in the center direction from the surface of the first positive electrode active material, and further, may be a region of 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, or 60 nm or less.

[0055]

[0056] According to one embodiment of the present invention, the molar ratio of boron to nickel present on the surface of the first positive electrode active material, i.e., the surface B / Ni value, may be 3 or more and 8 or less, and for specific examples, 3.1 or more, 3.2 or more, 3.3 or more, 3.4 or more, 3.5 or more, 3.6 or more, 3.7 or more, 3.8 or more, 3.9 or more, 4 or more, 4.1 or more, 4.2 or more, 4.3 or more, 4.4 or more, 4.5 or more, 4.6 or more, 4.7 or more, 4.8 or more, 4.9 or more or 5 or more, and further, 7.9 or less, 7.8 or less, 7.7 or less, 7.6 or less, 7.5 or less, 7.4 or less, 7.3 or less, 7.2 or less, 7.1 or less, 7 or less, 6.9 or less, 6.8 or less, 6.7 or less, It may be 6.6 or less, 6.5 or less, 6.4 or less, 6.3 or less, 6.2 or less, 6.1 or less, or 6 or less. When the above range is satisfied, the first positive electrode active material manufactured through the subsequent process includes an appropriate amount of Li-BO solid solution, thereby alleviating an increase in viscosity of the slurry including the first positive electrode active material and suppressing gel formation.

[0057] If the molar ratio of boron to nickel present on the surface of the first positive electrode active material exceeds the above-mentioned range, the capacity and lifespan are reduced due to the excessive presence of the Li-BO solid solution, and if it is below the above-mentioned range, the Li-BO solid solution is present at a level below an appropriate level, so that the surface energy of the first positive electrode active material increases, which may increase gel formation during slurry production, and the viscosity of the slurry including the first positive electrode active material produced through a subsequent process is greatly increased.

[0058]

[0059] According to one embodiment of the present invention, the molar ratio of boron to nickel present on the surface of the first positive electrode active material can be obtained through electron spectroscopy chemical analysis (ESCA) using a K-alpha XPS device from Thermo Fisher. In this case, the surface analyzed through the ESCA analysis may be a region extending from the outermost edge of the first positive electrode active material toward the center up to 10 nm.

[0060]

[0061] 2. Second positive electrode active material

[0062] A second positive electrode active material according to one embodiment of the present invention is a positive electrode active material comprising a lithium transition metal composite oxide containing nickel at 60 mol% or more based on the total transition metal; and a boron coating formed on the surface of the lithium transition metal composite oxide, wherein the average particle diameter of the second positive electrode active material is 10 μm or more and 20 μm or less, and the molar ratio of boron to nickel present on the surface of the second positive electrode active material may be 9 or more.

[0063]

[0064] According to one embodiment of the present invention, the average particle diameter of the second positive electrode active material is a large-diameter positive electrode active material of 10 µm or more and 20 µm or less, and as a specific example, the average particle diameter of the second positive electrode active material may be 10.2 µm or more, 10.4 µm or more, 10.6 µm or more, 10.8 µm or more, 11 µm or more, 11.2 µm or more, 11.4 µm or more, 11.6 µm or more, 11.8 µm or more, or 12 µm or more, and further, 19.5 µm or less, 19 µm or less, 18.5 µm or less, 18 µm or less, 17.5 µm or less, 17 µm or less, 16.5 µm or less, 16 µm or less, 15.5 µm or less, or 15 µm or less.

[0065]

[0066] According to one embodiment of the present invention, the boron coating portion is formed on the surface of the large-diameter positive electrode active material and may include an ion-conductive lithium boron oxide (LBO) intermediate phase. A more detailed description of the Li-BO solid solution included in the boron coating portion will be provided below.

[0067] According to one embodiment of the present invention, the boron coating portion may be formed on the entire or a portion of the surface of the second positive electrode active material, and when the boron coating portion is formed on the entire surface of the second positive electrode active material, it may be referred to as a boron coating layer.

[0068] According to one embodiment of the present invention, the boron coating portion may occupy an area of ​​85% or more of the entire surface of the first positive electrode active material, and for specific examples, may occupy an area of ​​85.5% or more, 86% or more, 86.5% or more, 87% or more, or 87.5% or more.

[0069] According to one embodiment of the present invention, the boron coating layer may be a region of 5 nm or more and 100 nm or less in the center direction from the surface of the second positive electrode active material. Specifically, the boron coating portion may be a region of 10 nm or more, 20 nm or more, 30 nm or more, 40 nm or more, or 50 nm or more in the center direction from the surface of the second positive electrode active material, and further, may be a region of 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, or 60 nm or less.

[0070]

[0071] According to one embodiment of the present invention, the molar ratio of boron to nickel present on the surface of the second positive electrode active material, that is, the surface B / Ni value, may be 9 or more and 45 or less, and for specific examples, 9.1 or more, 9.2 or more, 9.3 or more, 9.4 or more, 9.5 or more, 9.6 or more, 9.7 or more, 9.8 or more, 9.9 or more, 10 or more, 10.1 or more, 10.2 or more, 10.3 or more, 10.4 or more, 10.5 or more, 10.6 or more, 10.7 or more, 10.8 or more, 10.9 or more or 11 or more, and also, 44.5 or less, 44 or less, 43.5 or less, 43 or less, 42.5 or less, 42 or less, 41.5 or less, 41 or less, 40.5 or less, 40 or less, 39.5 or less. Below, it may be 39 or less, 38.5 or less, 38 or less, 37.5 or less, or 37 or less. When the above range is satisfied, the second positive electrode active material manufactured through the subsequent process includes an appropriate amount of Li-BO solid solution, thereby alleviating an increase in viscosity of the slurry including the second positive electrode active material and suppressing gel formation.

[0072] If the molar ratio of boron to nickel present on the surface of the second positive electrode active material exceeds the above-mentioned range, the capacity and lifespan are reduced due to the excessive presence of the Li-BO solid solution, and if it is below the above-mentioned range, the Li-BO solid solution is present at a level below an appropriate level, so that the surface energy of the second positive electrode active material increases, which may increase gel formation during slurry production, and the viscosity of the slurry including the second positive electrode active material produced through a subsequent process is greatly increased.

[0073]

[0074] According to one embodiment of the present invention, the molar ratio of boron to nickel present on the surface of the second positive electrode active material can be obtained through electron spectroscopy chemical analysis (ESCA) using a K-alpha XPS device from Thermo Fisher. In this case, the surface analyzed through the ESCA analysis may be a region of up to 10 nm from the outermost portion of the second positive electrode active material.

[0075]

[0076] The first positive electrode active material and the second positive electrode active material according to one embodiment of the present invention may each include a lithium transition metal composite oxide having an average composition represented by the following chemical formula 1.

[0077] [Chemical Formula 1]

[0078] Li x Ni a Co b Mn c M d O2

[0079] In the above chemical formula 1,

[0080] M is at least one selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P and S,

[0081] 0.8≤x≤1.2, 0.6≤a<1, 0 <b<0.2, 0<c<0.2, 0≤d<0.1, a+b+c+d=1이다.

[0082]

[0083] According to one embodiment of the present invention, the x represents the molar ratio of lithium in the lithium composite transition metal oxide, and may be 0.8 or more and 1.2 or less, and as a specific example, may be 0.84 or more, 0.88 or more, 0.92 or more, 0.96 or more, or 1.00 or more, and may also be 1.18 or less, 1.16 or less, 1.14 or less, 1.12 or less, 1.10 or less, 1.08 or less, 1.06 or less, or 1.04 or less.

[0084]

[0085] According to one embodiment of the present invention, the a represents the molar ratio of nickel in the lithium composite transition metal oxide, and may be 0.6 or more and less than 1.0, and for specific examples, may be 0.62 or more, 0.64 or more, 0.66 or more, 0.68 or more, 0.7 or more, 0.72 or more, 0.74 or more, 0.76 or more, 0.78 or more, or 0.8 or more, and may also be 0.99 or less, 0.98 or less, 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.9 or less, or 0.89 or less. According to one embodiment of the present invention, when the molar ratio of nickel in the lithium composite transition metal oxide has the above-mentioned range, the capacity characteristics may be excellent.

[0086]

[0087] According to one embodiment of the present invention, b represents a molar ratio of cobalt in a lithium composite transition metal oxide, and may be greater than 0 and less than 0.2, and as a specific example, may be 0.02 or more, 0.04 or more, 0.06 or more, 0.08 or more, or 0.1 or more, and may also be 0.19 or less, 0.18 or less, 0.17 or less, 0.16 or less, or 0.15 or less.

[0088]

[0089] According to one embodiment of the present invention, c represents a molar ratio of manganese in a lithium composite transition metal oxide, and may be greater than 0 and less than 0.2, and as a specific example, may be 0.02 or more, 0.04 or more, 0.06 or more, 0.08 or more, or 0.1 or more, and may also be 0.19 or less, 0.18 or less, 0.17 or less, 0.16 or less, or 0.15 or less.

[0090]

[0091] According to one embodiment of the present invention, the d represents a molar ratio of a doping element, i.e., M, in a lithium composite transition metal oxide, and may be 0 or more and less than 0.1, and as a specific example, may be 0.001 or more, 0.002 or more, 0.003 or more, 0.004 or more, or 0.005 or more, and further may be 0.09 or less, 0.08 or less, 0.07 or less, 0.06 or less, or 0.05 or less.

[0092] According to one embodiment of the present invention, the M may be Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P, S or a combination thereof.

[0093]

[0094] A cathode material according to another embodiment of the present invention may include both the first cathode active material and the second cathode active material.

[0095]

[0096] According to another embodiment of the present invention, the second positive electrode active material may be included in an amount of 40 parts by weight or more and 90 parts by weight or less based on 100 parts by weight of the sum of the first positive electrode active material and the second positive electrode active material included in the positive electrode material, and for specific examples, it may be included in an amount of 45 parts by weight or more, 50 parts by weight or more, 55 parts by weight or more, 60 parts by weight or more, 65 parts by weight or more, or 70 parts by weight or more, and further, it may be included in an amount of 89 parts by weight or less, 88 parts by weight or less, 87 parts by weight or less, 86 parts by weight or less, 85 parts by weight or less, 84 parts by weight or less, 83 parts by weight or less, 82 parts by weight or less, 81 parts by weight or less, or 80 parts by weight or less. When the above range is satisfied, the energy density of the electrode to be manufactured can be improved.

[0097]

[0098] <Cathode material manufacturing method>

[0099] The present invention provides a method for manufacturing a cathode material.

[0100] According to one embodiment of the present invention, a method for manufacturing a cathode material is provided, which is a method for manufacturing each of the first cathode active material and the second cathode active material, wherein the method for manufacturing the first cathode active material and the method for manufacturing the second cathode active material each include a step (S1) of mixing and firing a cathode active material precursor containing a transition metal hydroxide and a lithium-containing raw material to manufacture a sintered product containing a lithium transition metal oxide; a step (S2) of washing the sintered product to manufacture a washed product having a residual lithium content of 0.3 to 0.9 wt% on the surface of the lithium transition metal oxide; a step (S3) of mixing the washed product and the boron-containing raw material and heat-treating the mixture at 200 to 400°C to form a coating layer containing a Li-BO solid solution on the surface of the lithium transition metal oxide; wherein the boron-containing raw material is used in an amount of 100 to 1500 wt ppm based on the washed product.

[0101]

[0102] Hereinafter, each step of a method for manufacturing a cathode material according to one embodiment of the present invention will be described.

[0103]

[0104] 1. (S1) Step

[0105] This is a step of manufacturing a sintered product containing a lithium transition metal oxide by mixing and sintering a positive electrode active material precursor containing a transition metal hydroxide and a lithium-containing raw material.

[0106] The above transition metal hydroxide can be prepared by purchasing and using a commercially available positive electrode active material precursor, or by using a method for preparing positive electrode active material precursors well known in the art. For example, the precursor can be prepared by adding an ammonium cation-containing complex forming agent and a basic compound to a transition metal solution containing a nickel-containing raw material, a cobalt-containing raw material, and a manganese-containing raw material, and performing a co-precipitation reaction.

[0107]

[0108] The above positive electrode active material precursor may include secondary particles formed by agglomeration of primary particles, and the positive electrode active material precursor may be represented by the following chemical formula 2.

[0109] [Chemical Formula 2]

[0110] Ni a` Co b` Mn c` M d` (OH)2

[0111] In the above chemical formula 2,

[0112] M is at least one selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P and S,

[0113] 0.5 <a`<1, 0<b`<0.4, 0<c`<0.3, 0<d`<0.05, a+b+c+d=1 이다.

[0114]

[0115] According to one embodiment of the present invention, the a` refers to the atomic fraction of nickel in the precursor and is 0.5 <a`<1, 바람직하게는 0.6≤a`<1, 0.7≤a`<1, 더 바람직하게는 0.7≤a`≤0.97일 수 있다.

[0116] According to one embodiment of the present invention, the b` means the atomic fraction of cobalt in the precursor, and is 0 <b`<0.4, 바람직하게는 0.1≤a`<0.4, 더 바람직하게는 0.1≤a`≤0.35일 수 있다.

[0117] According to one embodiment of the present invention, c` means the atomic fraction of cobalt in the precursor, and is 0 <c`<0.3, 바람직하게는 0<c`≤0.25, 더 바람직하게는 0.1≤a`≤0.25일 수 있다.

[0118] The above d` means the atomic fraction of the doping element M in the precursor, and 0 <d`<0.05, 바람직하게는 0.01≤a`<0.05, 더 바람직하게는 0.01≤a`≤0.04일 수 있다.

[0119]

[0120] According to one embodiment of the present invention, the method for manufacturing the first positive electrode active material and the method for manufacturing the second positive electrode active material may differ in the average particle diameter of the positive electrode active material precursor used, and other conditions may be the same.

[0121] According to one embodiment of the present invention, the average particle diameter of the positive electrode active material precursor used in the method for manufacturing the first positive electrode active material may be 2 µm or more and 7.5 µm or less, and as a specific example, may be 2.5 µm or more, 3 µm or more, 3.5 µm or more, 4 µm or more, or 4.5 µm or more, and further, may be 7 µm or less, 6.5 µm or less, 6 µm or less, 5.5 µm or less, or 5 µm or less.

[0122] According to one embodiment of the present invention, the average particle diameter of the positive electrode active material precursor used in the method for manufacturing the second positive electrode active material may be 9 µm or more and 19 µm or less, and as a specific example, may be 10 µm or more, 11 µm or more, 12 µm or more, 12.5 µm or more, or 13 µm or more, and further, may be 18 µm or less, 17 µm or less, 16 µm or less, 15 µm or less, or 14.5 µm or less.

[0123]

[0124] According to one embodiment of the present invention, the lithium-containing raw material may include at least one selected from lithium hydroxide hydrate, lithium carbonate, and lithium hydroxide. Specifically, the lithium-containing raw material may be lithium hydroxide hydrate, more specifically, LiOH·H2O. In this case, the reactivity between a precursor having a high atomic fraction of nickel among the metal elements in the precursor and the lithium-containing raw material may be improved.

[0125] According to one embodiment of the present invention, the positive electrode active material precursor and the lithium-containing raw material may be mixed in a molar ratio of 1:1.0 to 1:1.10, specifically 1:1.03 to 1:1.08, and more specifically 1:1.05 to 1:1.07.

[0126] According to one embodiment of the present invention, when the positive electrode active material precursor and the lithium-containing raw material are mixed in the molar ratio, the capacity of the positive electrode active material does not decrease, the problem of unreacted Li remaining as a byproduct does not occur, and the phenomenon of capacity decrease and separation of positive electrode active material particles after firing can also be suppressed.

[0127]

[0128] According to one embodiment of the present invention, the sintering in step 1) may be performed at a temperature of 700°C to 950°C, and specifically, 750°C to 850°C, more specifically, 750°C to 800°C, or 730°C to 760°C. When the sintering temperature is within the above range, crystals can be formed in an appropriate size, and the process cost may not be high.

[0129]

[0130] According to one embodiment of the present invention, the firing of step 1) may be performed in an oxygen atmosphere. In this case, a fired product having a structurally stable phase can be formed.

[0131]

[0132] According to one embodiment of the present invention, the firing of step 1) may be performed for 5 to 24 hours. Specifically, the firing may be performed for 5 to 12 hours, and more specifically, for 5 to 10 hours. When the firing time is within the above range, the firing may be performed well without deviation (uniformly) depending on the firing position.

[0133]

[0134] 2. (S2) Step

[0135] According to one embodiment of the present invention, step (S2) is a step of washing the sintered product manufactured in step (S1) to manufacture a washed product having a residual lithium content of 0.3 to 0.9 wt% on the surface of a lithium transition metal oxide.

[0136] According to one embodiment of the present invention, the washing is a process for controlling residual lithium on the surface of the lithium transition metal oxide manufactured in step (S1), and through the washing, the amount of residual lithium on the surface of the lithium transition metal oxide can be adjusted to 0.3 to 0.9 wt%, specifically 0.3 to 0.8 wt%, or 0.3 to 0.7 wt%. By manufacturing a washed product with a controlled residual lithium amount as described above, the first cathode active material and the second cathode active material of the present invention can ultimately manufacture a cathode active material including a Li-BO solid solution.

[0137] Specifically, the residual lithium is used as a reactant for manufacturing a coating layer including a Li-BO solid solution. When the residual lithium is less than 0.4 wt%, the residual lithium content on the surface capable of generating a Li-BO solid solution is insufficient, so that lithium inside the lithium transition metal oxide core participates in the reaction for forming a Li-BO solid solution, and in this case, the collapse of the layer structure composed of the core and the coating layer is accelerated, which may cause a problem in that the resistance increase rate increases when used in a lithium secondary battery. In addition, when the residual lithium is more than 0.9 wt%, even after the formation of the Li-BO solid solution, residual lithium that has not reacted with boron exists, so that the diffusion of lithium decreases, which may cause a decrease in capacity and an increase in resistance when used in a lithium secondary battery.

[0138] According to one embodiment of the present invention, the residual lithium may be at least one selected from the group consisting of LiOH and Li2CO3, but is not limited thereto.

[0139]

[0140] According to one embodiment of the present invention, the washing may be performed by adding 30 to 150 parts by weight of the washing solution based on 100 parts by weight of the sintered product, and specifically, the washing solution may be added 30 to 85 parts by weight, or 30 to 80 parts by weight, based on 100 parts by weight of the sintered product. As a result of the washing, a washed product may be manufactured.

[0141] According to one embodiment of the present invention, as the amount of the washing solution added based on 100 parts by weight of the sintered product increases, the residual lithium on the surface of the lithium transition metal oxide decreases, and thus the molar ratio of boron to nickel present on the surface of the first positive electrode active material and the second positive electrode active material may decrease. In this way, by adjusting the content of the washing solution, the residual lithium on the surface of the lithium transition metal oxide can be controlled as intended in the present invention, and the sintered product can be prevented from gelling and the lithium within the sintered product can be prevented from being excessively dissolved.

[0142] According to one embodiment of the present invention, the amount of residual lithium remaining in each of the sintered product and the washed product can be calculated by stirring 5 g of the sintered product in 100 ml of distilled water for 5 minutes using an 888titrando device from Metrohm, filtering the resulting reaction liquid, collecting only the reaction liquid, and titrating it with a 0.1 M HCl aqueous solution.

[0143]

[0144] According to one embodiment of the present invention, the washing may be performed at 10 to 80°C, specifically at 15 to 65°C, or at 20 to 30°C.

[0145] According to one embodiment of the present invention, the washing may be performed for 1 to 120 minutes, specifically 3 to 60 minutes, or 5 to 30 minutes.

[0146]

[0147] According to one embodiment of the present invention, the solvent of the washing solution may be at least one selected from deionized water, distilled water, and ethanol. Specifically, the solvent of the washing solution may be deionized water and / or distilled water, but is not limited thereto.

[0148]

[0149] According to one embodiment of the present invention, after the washing step and before the step (S3), an additional pre-processing step may be performed. The drying step is intended to remove moisture from the lithium transition metal oxide containing moisture through the washing step, and may be performed at a temperature of 60°C to 150°C after removing the moisture using a vacuum pump. Specifically, the drying step may be performed for 12 hours or more under temperature conditions of 60°C to 150°C.

[0150]

[0151] 3. (S3) Step

[0152] According to one embodiment of the present invention, the step (S3) is a step of mixing the water-washed product manufactured in the step (S2) and the boron-containing raw material, and heat-treating the mixture at 200°C to 350°C to form a coating layer containing a Li-BO solid solution on the surface of the lithium transition metal oxide.

[0153] According to one embodiment of the present invention, the residual lithium remaining on the surface of the lithium transition metal oxide after the step (S2) reacts with the boron-containing raw material to form a coating layer including a Li-BO solid solution, thereby improving the life characteristics of the battery when the first positive electrode active material and / or the second positive electrode active material is applied to the battery.

[0154]

[0155] According to one embodiment of the present invention, the boron-containing raw material may be at least one selected from H3BO3, B2O3, B2H4O4, LiBO2, Li2B4O7, and AlBO3. Specifically, the boron-containing raw material may be H3BO3, B2O3, and more specifically, H3BO3. In this case, since the melting point of the boron-containing raw material is low, a uniform coating layer can be formed.

[0156]

[0157] According to one embodiment of the present invention, the boron-containing raw material may be added in an amount of 100 to 1500 ppm by weight based on the washed product, and for specific examples, it may be added in an amount of 110 to 1400 ppm, 120 to 1300 ppm, or 130 to 1200 ppm by weight. When the content of the boron-containing raw material is within the above range, the capacity of the battery may be improved, and the resulting coating portion may suppress direct reaction between the electrolyte and the lithium transition metal oxide, thereby improving the long-term performance characteristics of the battery.

[0158]

[0159] According to one embodiment of the present invention, the residual lithium on the surface of the lithium transition metal oxide, the content of which is controlled in the step (S2), can react with the boron-containing raw material through heat treatment in the step (S3) to participate as a reactant in the formation of a Li-BO solid solution.

[0160]

[0161] However, if the Li-BO solution exceeds an appropriate level, the electrochemical properties are seriously deteriorated during electrode manufacturing, and if it is below an appropriate level, the surface energy of the positive electrode active material increases, which has a negative effect on the stability of the slurry.

[0162] Accordingly, in the step of forming the boron coating portion, the present invention adds the boron-containing material in a weight range of 100 ppm to 1500 ppm to the dried lithium transition metal oxide, and by controlling the washing solution in an appropriate amount and the heat treatment temperature in an appropriate range, the molar ratio of boron to nickel present on the surface of the positive electrode active material, i.e., the surface B / Ni value, is appropriately controlled according to the average particle size of the positive electrode active material, thereby allowing the content of the Li-BO solid solution included in each positive electrode active material to be controlled to an appropriate level.

[0163]

[0164] According to one embodiment of the present invention, the surface B / Ni values ​​of the first positive electrode active material and the second positive electrode active material can be controlled depending on the amount of boron-containing raw material added. In other words, the amount of boron-containing raw material added and the surface B / Ni values ​​of the first positive electrode active material and the second positive electrode active material can have a proportional correlation.

[0165] According to one embodiment of the present invention, when manufacturing the first positive electrode active material, the boron-containing raw material may be added in an amount of 100 ppm by weight or more and 800 ppm by weight or less based on the washed product, and for specific examples, may be added in an amount of 150 ppm by weight or more, 200 ppm by weight or more, 250 ppm by weight or more, 300 ppm by weight or more, 350 ppm by weight or more, 400 ppm by weight or more, or 450 ppm by weight or more, and further may be added in an amount of 790 ppm by weight or less, 780 ppm by weight or less, 770 ppm by weight or less, 760 ppm by weight or less, 750 ppm by weight or less, 740 ppm by weight or less, or 730 ppm by weight or less. When the above range is satisfied, the surface B / Ni value of the first positive electrode active material can be adjusted to 3 or more and 8 or less.

[0166] According to one embodiment of the present invention, when manufacturing the second positive electrode active material, the boron-containing raw material may be added in an amount of 450 ppm by weight or more and 1500 ppm by weight or less based on the washed product, and for specific examples, may be added in an amount of 500 ppm by weight or more, 520 ppm by weight or more, 540 ppm by weight or more, 560 ppm by weight or more, 580 ppm by weight or more, 600 ppm by weight or more, or 620 ppm by weight or more, and may also be added in an amount of 1500 ppm by weight or less, 1400 ppm by weight or less, 1300 ppm by weight or less, 1200 ppm by weight or less, 1100 ppm by weight or less, 1000 ppm by weight or less, or 9000 ppm by weight or less. When the above range is satisfied, the surface B / Ni value of the second positive electrode active material can be adjusted to 9 or more.

[0167]

[0168] According to one embodiment of the present invention, the residual lithium on the surface of the lithium transition metal oxide can be controlled as intended in the present invention by controlling the heat treatment temperature. For example, as the heat treatment temperature increases, the boron-containing raw material on the surface of the lithium transition metal oxide can diffuse toward the center of the lithium transition metal oxide, thereby lowering the surface B / Ni.

[0169] According to one embodiment of the present invention, the heat treatment temperature may be performed in a range of 200°C or more and 305°C or less, and as a specific example, may be performed at 205°C or more, 210°C or more, 215°C or more, 220°C or more, 225°C or more, 230°C or more, and may also be performed at 304°C or less, 303°C or less, 302°C or less, 301°C or less, 300°C or less, or 299°C or less.

[0170] According to one embodiment of the present invention, the heat treatment can be performed under an oxygen atmosphere, a nitrogen atmosphere, or an air atmosphere. Specifically, the heat treatment can be performed under an air atmosphere.

[0171] According to one embodiment of the present invention, the heat treatment may be performed for 5 to 24 hours. When the heat treatment time is within the above range, an appropriate coating layer can be formed, and production efficiency can be improved.

[0172]

[0173] Bipolar

[0174] According to one embodiment of the present invention, a cathode including the cathode material is provided.

[0175] Specifically, the positive electrode includes a positive electrode current collector, and a positive electrode active material layer formed on the positive electrode current collector and including the positive electrode material.

[0176] According to one embodiment of the present invention, the positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the current collector to increase the adhesive strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0177] According to one embodiment of the present invention, the positive electrode active material layer may include a conductive material and a binder together with the positive electrode material described above.

[0178] According to one embodiment of the present invention, at this time, the conductive material is used to provide conductivity to the electrode, and in the battery to be constructed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any particular limitation. 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, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like, and one type alone or a mixture of two or more types thereof may be used. The conductive material may typically be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0179] According to one embodiment of the present invention, the binder serves to improve adhesion between positive electrode active material particles and adhesion between the positive electrode material and the current collector. Specific examples thereof include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The binder may be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0180] According to one embodiment of the present invention, the positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode material described above is used. Specifically, the positive electrode material and, optionally, a binder and a conductive agent are mixed or dispersed in a solvent to form a composition for forming a positive electrode active material layer, and the composition is applied onto a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode material, binder, and conductive agent are as described above.

[0181] According to one embodiment of the present invention, the solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these may be used alone or as a mixture of two or more. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode material, conductive material, and binder in consideration of the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0182] Additionally, in another method, the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support, and then laminating the resulting film on a positive electrode current collector by peeling it off from the support.

[0183]

[0184] Lithium secondary battery

[0185] According to one embodiment of the present invention, an electrochemical device including the positive electrode is provided. The electrochemical device may be, specifically, a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.

[0186] According to one embodiment of the present invention, the lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode is as described above. In addition, the lithium secondary battery may optionally further include a battery container that houses an electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0187] According to one embodiment of the present invention, in the lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0188] According to one embodiment of the present invention, the negative electrode 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., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0189] According to one embodiment of the present invention, the negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0190] According to one embodiment of the present invention, a compound capable of reversible intercalation and deintercalation of lithium may be used as the negative electrode active material. 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 alloy, Sn alloy, or Al alloy; SiO x (0 < x < 2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, 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.

[0191] Additionally, the binder and the conductive material may be the same as those described above for the positive electrode.

[0192] According to one embodiment of the present invention, the negative electrode active material layer may be manufactured by, for example, applying a negative electrode forming composition prepared by dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, onto a negative electrode current collector and drying the coating, or by casting the negative electrode forming composition onto a separate support and then laminating the film obtained by peeling it off from the support onto a negative electrode current collector.

[0193] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used as a separator in lithium secondary batteries can be used without special restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture retention capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0194] In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0195] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0196] According to one embodiment of the present invention, the organic solvent may be used without particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, which may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, 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 linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0197] According to one embodiment of the present invention, the lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable that the concentration of the lithium salt be used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0198] According to one embodiment of the present invention, in addition to the electrolyte components, the electrolyte may further include one or more additives, such as, for example, a haloalkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, a cyclic ether, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0199] According to one embodiment of the present invention, a lithium secondary battery including a cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0200]

[0201] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0202]

[0203] Manufacturing Example 1 - Manufacturing of large-diameter positive electrode active material (B)

[0204] The average particle size is 12.5㎛, and Ni 0.97 Co 0.01 Mn 0.02 After mixing the transition metal hydroxide with the composition of (OH)2 and LiOH in a ratio of 1:1.04, the final composition of the positive electrode active material is LiNi 0.94 Co 0.01 Mn 0.02 Al 0.03 Aluminum hydroxide (Al(OH)3) was additionally mixed in an amount of 3 mol% based on the above transition metal hydroxide to form O2, and the product was manufactured by firing at a temperature of 730°C for 12 hours in an oxidizing atmosphere. The amount of residual lithium remaining in the product was 1.1 wt%.

[0205] 100g of the above-mentioned product was mixed with 40g of distilled water, stirred for 5 minutes, and then washed with water having a residual lithium content of 0.7 wt% (Composition: LiNi 0.94 Co 0.01 Mn 0.02 Al 0.03O2) was manufactured. The manufactured washing product and, based on the washing product, H3BO3 as a boron-containing raw material was mixed at 600 ppm by weight and heat-treated at a temperature of 295°C for 5 hours to manufacture a cathode active material having an average particle size of 13 μm and a coating layer including a Li-BO solid solution formed on the surface.

[0206] Meanwhile, the amount of residual lithium remaining in each of the sintered product and the washed product was calculated by stirring 5 g of the sintered product or the washed product in 100 ml of distilled water for 5 minutes, filtering the mixture, collecting only the reaction liquid, and titrating it with a 0.1 M HCl aqueous solution using an 888titrando device from Metrohm.

[0207]

[0208] Manufacturing Example 2 - Manufacturing of large-diameter positive electrode active material (C)

[0209] The washed product manufactured according to the above Manufacturing Example 1 and the positive electrode active material having an average particle diameter of 13 μm and a coating layer including a Li-BO solid solution formed on the surface were manufactured in the same manner as Manufacturing Example 1, except that 900 ppm by weight of H3BO3 was mixed as a boron-containing raw material based on the washed product.

[0210]

[0211] Manufacturing Example 3 - Manufacturing of large-diameter positive electrode active material (F)

[0212] The washed product manufactured according to the above Manufacturing Example 1 and the boron-containing raw material H3BO3 was mixed at 700 ppm by weight based on the washed product and heat-treated at a temperature of 275°C for 5 hours, and a positive electrode active material having an average particle size of 13 μm and a coating layer including a Li-BO solid solution formed on the surface was manufactured in the same manner as Manufacturing Example 1, except that the washed product was mixed with the boron-containing raw material at 700 ppm by weight and heat-treated at a temperature of 275°C for 5 hours.

[0213]

[0214] Manufacturing Example 4 - Manufacturing of large-diameter positive electrode active material (G)

[0215] The above-mentioned washed product manufactured according to the above-mentioned Manufacturing Example 1 and the positive electrode active material having an average particle diameter of 13 μm and a coating layer including a Li-BO solid solution formed on the surface were manufactured in the same manner as in Manufacturing Example 1, except that 700 ppm by weight of H3BO3 was mixed as a boron-containing raw material based on the above-mentioned washed product.

[0216]

[0217] Manufacturing Example 5 - Manufacturing of small-particle cathode active material (a)

[0218] The average particle size is 3.5㎛, and Ni 0.95 Co 0.02 Mn 0.03 After mixing the transition metal hydroxide with the composition of (OH)2 and LiOH in a ratio of 1:1.04, the final composition of the positive electrode active material is LiNi 0.93 Co 0.02 Mn 0.03 Al 0.02 Aluminum hydroxide (Al(OH)3) was additionally mixed in an amount of 2 mol% based on the above transition metal hydroxide to form O2, and the product was manufactured by firing at a temperature of 730°C for 12 hours in an oxidizing atmosphere. The amount of residual lithium remaining in the product was 1.1 wt%.

[0219] 100g of the above-mentioned product was mixed with 40g of distilled water, stirred for 5 minutes, and then washed with water having a residual lithium content of 0.7 wt% (Composition: LiNi 0.93 Co 0.02 Mn 0.03 Al 0.02 O2) was manufactured. The manufactured water-washed product and H3BO3700 ppm as a boron-containing raw material were mixed and heat-treated at a temperature of 295°C for 5 hours to manufacture a cathode active material having an average particle diameter of 4 μm and a coating layer including a Li-BO solid solution formed on the surface.

[0220] Meanwhile, the amount of residual lithium remaining in each of the sintered product and the washed product was calculated by stirring 5 g of the sintered product or the washed product in 100 ml of distilled water for 5 minutes, filtering the mixture, collecting only the reaction liquid, and titrating it with a 0.1 M HCl aqueous solution using an 888titrando device from Metrohm.

[0221]

[0222] Manufacturing Example 6 - Manufacturing of small-particle cathode active material (b)

[0223] A positive electrode active material having an average particle size of 4 μm and a coating layer including a Li-BO solid solution formed on the surface was manufactured in the same manner as in Manufacturing Example 5, except that the washed product manufactured according to Manufacturing Example 5 and the washed product were mixed with 700 ppm by weight of H3BO3 as a boron-containing raw material and heat-treated at a temperature of 275°C for 5 hours.

[0224]

[0225] Comparative Manufacturing Example 1 - Manufacturing of Large-Area Positive Electrode Active Material (A)

[0226] The washed product manufactured according to the above Manufacturing Example 1 and the positive electrode active material having an average particle diameter of 13 μm and a coating layer including a Li-BO solid solution formed on the surface were manufactured in the same manner as Manufacturing Example 1, except that 300 ppm by weight of H3BO3 was mixed as a boron-containing raw material based on the washed product.

[0227]

[0228] Comparative Manufacturing Example 2 - Manufacturing of Large-Area Positive Electrode Active Material (D)

[0229] 100 g of the above-mentioned sintered product manufactured according to the above-mentioned manufacturing example 1 was mixed with 45 g of distilled water and stirred for 5 minutes, and then a washed product (composition: LiNi) having a residual lithium content of 0.742 wt% was obtained. 0.94 Co 0.01 Mn 0.02 Al 0.03A positive electrode active material having an average particle diameter of 13 μm and a coating layer containing a Li-BO solid solution on the surface was manufactured using the same method as in Manufacturing Example 1, except that O2) was manufactured.

[0230] Meanwhile, the amount of residual lithium remaining in the above-mentioned washed product was calculated by using Metrohm's 888titrando equipment, stirring 5 g of the above-mentioned washed product in 100 ml of distilled water for 5 minutes, filtering it, collecting only the reaction liquid, and titrating it with a 0.1 M HCl aqueous solution.

[0231]

[0232] Comparative Manufacturing Example 3 - Manufacturing of Large-Area Positive Electrode Active Material (E)

[0233] 100 g of the above-mentioned sintered product manufactured according to the above-mentioned manufacturing example 1 was mixed with 60 g of distilled water and stirred for 5 minutes, and then a washed product (composition: LiNi) having a residual lithium content of 0.532 wt% was obtained. 0.94 Co 0.01 Mn 0.02 Al 0.03 A positive electrode active material having an average particle diameter of 13 μm and a coating layer containing a Li-BO solid solution on the surface was manufactured using the same method as in Manufacturing Example 1, except that O2) was manufactured.

[0234] Meanwhile, the amount of residual lithium remaining in the above-mentioned washed product was calculated by using Metrohm's 888titrando equipment, stirring 5 g of the above-mentioned washed product in 100 ml of distilled water for 5 minutes, filtering it, collecting only the reaction liquid, and titrating it with a 0.1 M HCl aqueous solution.

[0235]

[0236] Comparative Manufacturing Example 4 - Manufacturing of Large-Area Positive Electrode Active Material (H)

[0237] The washed product manufactured according to the above Manufacturing Example 1 and the boron-containing raw material H3BO3 was mixed at 700 ppm by weight based on the washed product and heat-treated at a temperature of 315°C for 5 hours, and a positive electrode active material having an average particle size of 13 μm and a coating layer including a Li-BO solid solution formed on the surface was manufactured in the same manner as Manufacturing Example 1, except that the washed product was mixed with the boron-containing raw material at 700 ppm by weight and heat-treated at a temperature of 315°C for 5 hours.

[0238]

[0239] Comparative Manufacturing Example 5 - Manufacturing of small-particle cathode active material (c)

[0240] A positive electrode active material having an average particle size of 4 μm and a coating layer including a Li-BO solid solution formed on the surface was manufactured in the same manner as in Manufacturing Example 5, except that the washed product manufactured according to Manufacturing Example 5 and the washed product were mixed with 700 ppm by weight of H3BO3 as a boron-containing raw material and heat-treated at a temperature of 315°C for 5 hours.

[0241]

[0242] Comparative Manufacturing Example 6 - Manufacturing of small-particle cathode active material (d)

[0243] The washed product manufactured according to the above Manufacturing Example 5 and the positive electrode active material having an average particle diameter of 4 μm and a coating layer including a Li-BO solid solution formed on the surface were manufactured in the same manner as Manufacturing Example 5, except that 2000 ppm by weight of H3BO3 was mixed as a boron-containing raw material based on the washed product.

[0244]

[0245] Example 1

[0246] The large-particle-diameter positive electrode active material manufactured in Manufacturing Example 1 and the small-particle-diameter positive electrode active material manufactured in Manufacturing Example 5 were mixed in a ratio of 8:2 to manufacture 500 g of positive electrode material, and the positive electrode material, conductive agent (SuperC65), and binder (KF1100) were mixed in a ratio of 95:2:3 to manufacture a mixture. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the solid content of the total positive electrode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0247]

[0248] Example 2

[0249] The large-particle-diameter positive electrode active material manufactured in Manufacturing Example 2 and the small-particle-diameter positive electrode active material manufactured in Manufacturing Example 5 were mixed in a ratio of 8:2 to manufacture 500 g of positive electrode material, and the positive electrode material, conductive agent (SuperC65), and binder (KF1100) were mixed in a ratio of 95:2:3 to manufacture a mixture. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the total solid content of the positive electrode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0250]

[0251] Example 3

[0252] 500 g of a cathode material including the large-diameter cathode active material manufactured in the above Manufacturing Example 3 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the solid content of the total cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0253]

[0254] Example 4

[0255] 500 g of a cathode material including the large-diameter cathode active material manufactured in the above Manufacturing Example 4 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the total solid content of the cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0256]

[0257] Example 5

[0258] 500 g of a cathode material including the small-particle cathode active material manufactured in the above Manufacturing Example 6 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the total solid content of the cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0259]

[0260] Example 6

[0261] 500 g of a cathode material including the small-particle cathode active material manufactured in the above Manufacturing Example 5 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the solid content of the total cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0262]

[0263] Comparative Example 1

[0264] The large-particle-diameter positive electrode active material manufactured in Comparative Manufacturing Example 1 and the small-particle-diameter positive electrode active material manufactured in Manufacturing Example 5 were mixed in a ratio of 8:2 to manufacture 500 g of positive electrode material, and the positive electrode material, conductive agent (SuperC65), and binder (KF1100) were mixed in a ratio of 95:2:3 to manufacture a mixture. Thereafter, N-Methyl-2-pyrrolidine (NMP) was added to the mixture so that the total solid content of the positive electrode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0265]

[0266] Comparative Example 2

[0267] The large-particle-diameter positive electrode active material manufactured in Comparative Manufacturing Example 2 and the small-particle-diameter positive electrode active material manufactured in Manufacturing Example 5 were mixed in a ratio of 8:2 to manufacture 500 g of positive electrode material, and the positive electrode material, conductive agent (SuperC65), and binder (KF1100) were mixed in a ratio of 95:2:3 to manufacture a mixture. Thereafter, N-Methyl-2-pyrrolidine (NMP) was added to the mixture so that the solid content of the total positive electrode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0268]

[0269] Comparative Example 3

[0270] The large-particle-diameter positive electrode active material manufactured in Comparative Manufacturing Example 3 and the small-particle-diameter positive electrode active material manufactured in Manufacturing Example 5 were mixed in a ratio of 8:2 to manufacture 500 g of positive electrode material, and the positive electrode material, conductive agent (SuperC65), and binder (KF1100) were mixed in a ratio of 95:2:3 to manufacture a mixture. Thereafter, N-Methyl-2-pyrrolidine (NMP) was added to the mixture so that the total solid content of the positive electrode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0271]

[0272] Comparative Example 4

[0273] 500 g of a cathode material including the large-diameter cathode active material manufactured in Comparative Manufacturing Example 4 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the solid content of the total cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0274]

[0275] Comparative Example 5

[0276] 500 g of a cathode material including the small-particle cathode active material manufactured in Comparative Manufacturing Example 5 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the total solid content of the cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0277]

[0278] Comparative Example 6

[0279] 500 g of a cathode material including the small-particle cathode active material manufactured in the above Comparative Manufacturing Example 6 was manufactured, and a mixture was manufactured by mixing the cathode material, conductive material (SuperC65), and binder (KF1100) in a ratio of 95:2:3. Thereafter, N-methyl-2-pyrrolidine (NMP) was added to the mixture so that the solid content of the total cathode active material in the mixture became 72%, and the mixture was stirred for 20 minutes at 1500 rpm using a homogenizer to manufacture a slurry.

[0280]

[0281] Experimental Example 1 - Measurement of B / Ni values

[0282] The molar ratio of boron to nigel present on the surface of each positive electrode active material manufactured in the above manufacturing examples / comparative manufacturing examples was measured through electron spectroscopy chemical analysis (ESCA) using a K-alpha XPS device from Thermo Fisher, and is shown in Tables 1 to 3 below. In this case, the surface analyzed through the ESCA analysis is the area from the outermost part of the positive electrode active material to 10 nm.

[0283]

[0284] Experimental Example 2 - Slurry Viscosity Measurement

[0285] The viscosity of the positive electrode slurry prepared in the above examples / comparative examples was measured at 25°C, SC4-25, 26z, and 16 rpm using a Brookfield viscometer. Since 30,000 cp was the measurement limit under these measurement conditions, this was set as the measurement stop point.

[0286]

[0287] Example Comparative Example 12123 Large-diameter positive electrode active material average particle size (㎛) 1313131313 Surface B / Ni 13.7 36.8 7.2 6.9 0.9 Small-diameter positive electrode active material average particle size (㎛) 44444 Surface B / Ni 5.15.15.15.15.1 Large-diameter positive electrode active material ratio 80% 80% 80% 80% 80% Slurry viscosity (10 4 cP)1.080.861.471.653.00

[0288] Example Comparative Example 344 Large-diameter positive electrode active material Average particle size (㎛) 131313 Surface B / Ni 13.0 10.15.2 Slurry viscosity (10 4 cP)0.51.121.7

[0289] Comparative Example 5656 Small-diameter positive electrode active material Average particle size (㎛) 4444 Surface B / Ni 5.3 5.1 1.9 9.1 Slurry viscosity (10 4 cP)1.351.493.003.00

[0290] Referring to Table 1 above, it was confirmed that the slurry viscosity of Examples 1 and 2, which are positive electrode materials including positive electrode active materials having different average particle sizes and in which the surface B / Ni was appropriately adjusted according to the average particle size of the positive electrode active materials, was significantly reduced compared to Comparative Examples 1 to 3.

[0291]

[0292] Referring to Table 2 above, it was confirmed that Examples 3 and 4, in which the surface B / Ni of the large-diameter positive electrode active material having an average particle size of 10 ㎛ or more was adjusted to 9 or more, had a significantly reduced slurry viscosity compared to Comparative Example 4, in which the surface B / Ni of the large-diameter positive electrode active material having an average particle size of 10 ㎛ or more was less than 9.

[0293]

[0294] Referring to Table 3 above, it was confirmed that Examples 5 and 6, in which the surface B / Ni of the small-diameter positive electrode active material having an average particle diameter of 2 ㎛ or more and 9 ㎛ or less was adjusted to 3 or more and 8 or less, had a significantly reduced slurry viscosity compared to Comparative Examples 5 and 6.

Claims

1. Containing at least one of the first positive electrode active material and the second positive electrode active material, Each of the first positive electrode active material and the second positive electrode active material is A lithium transition metal composite oxide containing nickel in an amount of 60 mol% or more relative to the total transition metal; and Including a boron coating formed on the surface of the above lithium transition metal composite oxide, The above first positive electrode active material is D 50 This is 2㎛ or more and 9㎛ or less, and the molar ratio of boron to nickel existing in the region from the outermost part of the first positive electrode active material to the center of 10 nm is 3 or more and 8 or less, The above second positive electrode active material is D 50 A cathode material having a diameter of 10 ㎛ or more and 20 ㎛ or less, and a molar ratio of boron to nickel existing in a region from the outermost part of the second cathode active material to the center of 10 nm or less of the second cathode active material is 9 or more and 45 or less.

2. In paragraph 1, The above lithium transition metal composite oxide is a cathode material having an average composition represented by the following chemical formula 1: [Chemical Formula 1] Li x Ni a Co b Mr c M d O2 In the above chemical formula 1, M1 is at least one selected from the group consisting of Al, Zr, B, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, Ce, Sn, Y, Zn, F, P and S, 0.8≤x≤1.2, 0.6≤a<1, 0 <b<0.2, 0<c<0.2, 0≤d<0.1, a+b+c+d=1이다.

3. In paragraph 1, A cathode material having a molar ratio of boron to nickel of 4 or more and 7 or less in a region extending from the outermost portion of the first cathode active material to the center within 10 nm.

4. In paragraph 1, A cathode material having a molar ratio of boron to nickel of 9 or more and 40 or less in a region extending from the outermost portion of the second cathode active material to the center within 10 nm.

5. In paragraph 1, D of the above first positive electrode active material 50 A cathode material having a size of 3㎛ or more and 8㎛ or less.

6. In paragraph 1, D of the above second positive electrode active material 50 A cathode material having a size of 10㎛ or more and 19㎛ or less.

7. In paragraph 1, A cathode material comprising both the first cathode active material and the second cathode active material.

8. In paragraph 7, A cathode material comprising 40 parts by weight or more and 90 parts by weight or less of the second cathode active material relative to 100 parts by weight of the sum of the first cathode active material and the second cathode active material.

9. In paragraph 7, A cathode material comprising 70 parts by weight or more and 80 parts by weight or less of the second cathode active material relative to 100 parts by weight of the sum of the first cathode active material and the second cathode active material.

10. A cathode comprising a cathode material according to any one of claims 1 to 9.

11. A lithium secondary battery comprising a positive electrode according to claim 10.