Positive electrode active material precursor and method for producing the same

Abstract

The present invention relates to a cathode active material precursor having a novel structure and a method for producing the same, which is a cathode active material precursor containing a composite transition metal hydroxide including a core portion containing first primary particles and a shell portion formed on the core portion and containing second primary particles, wherein, in a cross section of the cathode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A1) of the second primary particles to the average cross-sectional area (A2) of the first primary particles is 3.00 or more and 10.0 or less.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0035835, filed on March 20, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a positive electrode active material precursor having a novel structure and a method for producing the same. [Background technology]

[0003] With the technological development and increasing demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source is rapidly increasing. Among secondary batteries, lithium secondary batteries, which have high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0004] Lithium-transition metal composite oxides are used as the positive electrode active material for lithium secondary batteries. Among them, lithium-cobalt composite metal oxides such as LiCoO2 are mainly used because of their high operating voltage and excellent capacity characteristics. However, LiCoO2 has very poor thermal properties due to the destabilization of its crystal structure caused by delithiation. In addition, the high cost of LiCoO2 limits its mass use as a power source in fields such as electric vehicles.

[0005] As a result, lithium manganese oxides (e.g., LiMnO2 or LiMn2O4), lithium iron phosphate compounds (e.g., LiFePO4), and lithium nickel oxides (e.g., LiNiO2) have been developed as alternatives to LiCoO2. Among these, lithium nickel oxides, which have a high reversible capacity of approximately 200 mAh / g and facilitate the realization of high-capacity batteries, have been the subject of active research and development. However, LiNiO2 has poorer thermal stability than LiCoO2. If an internal short circuit occurs during charging due to external pressure, the positive electrode active material itself decomposes, resulting in battery explosion and fire. Therefore, NCM-based positive electrode active materials, in which part of the Ni is replaced with Co, Mn, and / or Al, have been developed as a way to improve the low thermal stability of LiNiO2 while maintaining its excellent reversible capacity.

[0006] Meanwhile, in recent years, with the increasing demand for high-energy density secondary batteries, high-nickel (High-Ni) NCM-based positive electrode active materials with a high nickel content have been developed to increase the capacity of the positive electrode active material. In addition, due to the recent rise in the price of Co, manganese-rich (Mn-rich) NCM-based positive electrode active materials with a relatively low Co content and capable of supporting high capacity have been developed.

[0007] While high-nickel NCM-based positive electrode active materials have the advantage of high capacity, their high nickel content leads to increased nickel oxidation at the same voltage range, resulting in increased lithium ion migration. This, in turn, reduces the structural stability of the positive electrode active material, resulting in poor long-term life and thermal stability. Therefore, there is a need for the development of high-nickel NCM-based positive electrode active materials that have high capacity characteristics while also offering excellent physical properties such as lifespan and thermal stability. In particular, in recent years, the development of single-particle positive electrode materials has accelerated to address the structural and thermal stability issues of secondary particle-based positive electrode materials. However, while small-particle-based positive electrode active materials have excellent cycle characteristics, they suffer from poor resistance characteristics. Therefore, there is a need for precursors capable of realizing small-particle-based positive electrode active materials with excellent cycle characteristics and resistance characteristics. Furthermore, the development of high-density Mn-rich NCM-based positive electrode active materials is needed to achieve high capacity and improved lifespan. Therefore, the development of precursors capable of realizing such high-density Mn-rich NCM-based positive electrode active materials is also needed. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Korean Patent Publication No. 10-2013-129449 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention is intended to solve the above problems, and an object of the present invention is to provide a positive electrode active material precursor with a novel structure that can achieve excellent life characteristics and resistance characteristics, and a method for producing the same.

[0010] Another object of the present invention is to provide a positive electrode active material precursor having a novel structure with uniform particle size and excellent sphericity, and a method for producing the same. [Means for solving the problem]

[0011] The present invention provides a positive electrode active material precursor and a method for producing the same.

[0012] (1) The present invention provides a cathode active material precursor comprising a composite transition metal hydroxide including a core portion containing first primary particles and a shell portion formed on the core portion and containing second primary particles, wherein in a cross section of the cathode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A1) of the second primary particles to the average cross-sectional area (A2) of the first primary particles is 3.00 or more and 10.0 or less.

[0013] (2) The present invention provides a method for manufacturing a cathode active material precursor having an average particle size (D 50 ) is 2.0 μm or more and 11.00 μm or less.

[0014] (3) The present invention provides the positive electrode active material precursor according to (1) or (2) above, wherein the core portion is in the form of a spherical secondary particle formed by aggregation of the first primary particles.

[0015] (4) The present invention provides the positive electrode active material precursor according to any one of (1) to (3) above, wherein the composite transition metal hydroxide has a composition represented by the following chemical formula 1:

[0016] [Chemical formula 1] [Ni a1 Co b1 M1 c1 M2 d1 ](OH)2

[0017] In the above Chemical Formula 1, M1 is one or more selected from Mn and Al, M2 is one or more selected from Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; 0.6≦a1<1, 0 <b1≦0.4、0<c1≦0.4、0≦d1≦0.2である。

[0018] (5) The present invention provides the positive electrode active material precursor according to any one of (1) to (3) above, wherein the composite transition metal hydroxide has a composition represented by the following chemical formula 2:

[0019] [Chemical formula 2] [Mn a2 Ni b2 Co c2 M d2 ](OH)2

[0020] In the above Chemical Formula 2, M is one or more selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; 0.5≦a2<1, 0 <b2≦0.5、0≦c2<0.5、0≦d2≦0.2である。

[0021] (6) In the present invention, in a cross section of the positive electrode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 4.60 or more and 5.00 or less, and the average particle size (D 50 ) is 2.00 μm or more and 5.00 μm or less.

[0022] (7) In the present invention, in a cross section of the positive electrode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 3.00 or more and 4.60 or less, and the average particle size (D 50 ) is 9.50 μm or more and 11.00 μm or less.

[0023] (8) The present invention provides a method for manufacturing a carbon nanotube having an average cross-sectional area (A1) of the first primary particles of 0.0100 μm 2 ~0.0200μm 2 The present invention provides a positive electrode active material precursor according to any one of (1) to (7) above, wherein

[0024] (9) The present invention is characterized in that the average cross-sectional area (A2) of the second primary particles is 0.0500 μm 2~0.1000μm 2 The present invention provides a positive electrode active material precursor according to any one of (1) to (8) above, wherein

[0025] (10) The present invention provides the positive electrode active material precursor according to any one of (1) to (9), wherein, in a cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion is 11.00% to 30.00%.

[0026] (11) The present invention provides the positive electrode active material precursor according to any one of (1) to (10), wherein, in a cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion is 2.00% to 7.00%.

[0027] (12) The present invention provides the cathode active material precursor according to any one of (1) to (11), wherein, in a cross section of the cathode active material precursor, a difference (CS) between a percentage (C) of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion and a percentage (S) of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion is 5.00% to 28.00%.

[0028] (13) The present invention provides the positive electrode active material precursor according to any one of (1) to (12), wherein in a cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​the core portion relative to the cross-sectional area of ​​the positive electrode active material precursor is 5.00% to 50.00%.

[0029] (14) The present invention provides a method for producing a cathode active material precursor using a reaction apparatus in which a reactor and a continuous pulverizer are connected, the method comprising the steps of: (S1) charging a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution into the reactor, forming cathode active material precursor seeds by a coprecipitation reaction while simultaneously operating the continuous pulverizer, discharging the cathode active material precursor seeds from the reactor to the continuous pulverizer, and re-introducing them from the continuous pulverizer into the reactor; and (S2) stopping the operation of the continuous pulverizer and growing cathode active material precursor particles in the reactor, wherein step (S1) is performed while gradually decreasing the pH, and step (S2) is performed while gradually increasing the pH.

[0030] (15) The present invention provides the method for producing a positive electrode active material precursor according to (14) above, wherein the step (S1) is carried out while gradually decreasing the pH within a range of pH 12.6 to 11.2.

[0031] (16) The present invention provides the method for producing a positive electrode active material precursor according to (14) or (15) above, wherein the step (S2) is carried out while gradually increasing the pH within a range of pH 11.2 to 12.6.

[0032] (17) The present invention provides a method for producing a cathode active material precursor according to any one of (1) to (9), comprising: (S1') a step of introducing a transition metal-containing solution and a basic aqueous solution into a reactor and forming cathode active material precursor seeds by a co-precipitation reaction; and (S2') a step of introducing a transition metal-containing solution and a basic aqueous solution into the reactor containing the cathode active material precursor seeds and growing cathode active material precursor particles by a co-precipitation reaction, wherein step (S1') is performed by gradually decreasing the pH from pH 12.0 or higher to pH 9.0 to 11.0, and then maintaining the pH within the range of pH 9.0 to 11.0; and step (S2') is performed by gradually decreasing the pH from pH 11.5 to 11.7 to pH 9.0 to 11.0, and then maintaining the pH within the range of pH 9.0 to 11.0.

[0033] (18) The present invention provides the method for producing a positive electrode active material precursor according to (17) above, wherein the step (S1′) is carried out in an oxidizing atmosphere. [Effects of the Invention]

[0034] The positive electrode active material precursor according to the present invention comprises a composite transition metal hydroxide including a core portion containing first primary particles and a shell portion formed on the core portion and containing second primary particles, and the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles satisfies 3.00 or more and 10.0 or less, thereby making it possible to provide a high-density positive electrode active material precursor having a uniform particle size and excellent sphericity.

[0035] Furthermore, when the cathode active material precursor is a high-nickel NCM-based cathode active material, calcining a mixture of the cathode active material precursor and a lithium-containing raw material can easily form a single-particle cathode active material with a high degree of single particle size, allowing lithium to easily diffuse into the core, resulting in a low-resistance cathode active material. Therefore, batteries using the cathode active material prepared from the cathode active material precursor according to the present invention can have improved capacity and life characteristics.

[0036] A method for producing a positive electrode active material according to one embodiment of the present invention uses a reaction apparatus in which a reactor and a continuous grinder are connected, and by appropriately adjusting the pH, it is possible to not only increase the production efficiency of a positive electrode active material precursor but also easily provide the positive electrode active material precursor according to the present invention.

[0037] In the method for producing a positive electrode active material according to another embodiment of the present invention, the positive electrode active material precursor according to the present invention can be easily provided by appropriately adjusting the pH and whether or not an ammonium ion-containing solution is added. [Brief explanation of the drawings]

[0038] [Figure 1]1 is a diagram schematically illustrating a reaction apparatus that can be used in the method for producing a positive electrode active material precursor of the present invention. [Figure 2] FIG. 2(A) is a graph showing the pH as a function of the production time of the positive electrode active material precursor of Example 1, and FIG. 2(B) is a graph showing the pH as a function of the production time of the positive electrode active material precursor of Comparative Example 1. [Figure 3] FIG. 3(A) is an SEM image of a cross section of the positive electrode active material precursor produced in Example 1, FIG. 3(B) is an SEM image of a cross section of the positive electrode active material precursor produced in Example 2, FIG. 3(C) is an SEM image of a cross section of the positive electrode active material precursor produced in Example 3, FIG. 3(D) is an SEM image of a cross section of the positive electrode active material precursor produced in Comparative Example 1, and FIG. 3(E) is an [Figure 4] 4(A) to 4(C) are images obtained by analyzing FIG. 3(A) using Image J. [Figure 5] 5(A) to 5(C) are images obtained by analyzing FIG. 3(D) using Image J. [Figure 6] 1A shows an SEM image of one embodiment of the present invention, and FIG. 1B shows a segmentation image obtained by processing the SEM image. [Figure 7] FIG. 1 is a diagram showing the definition of the minor and major axes for calculating the aspect ratio of a particle. [Figure 8] FIG. 8(A) is an SEM image of a positive electrode active material produced using the positive electrode active material precursor of Example 1, and FIG. 8(B) is an SEM image of a positive electrode active material produced using the positive electrode active material precursor of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0039] For better understanding of the present invention, the present invention will be described in more detail below.

[0040] The terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that the inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0041] As used herein, the terms "comprises," "comprises," or "having" are intended to specify the presence of embodied features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the presence or possible addition of one or more other features, numbers, steps, components, or combinations thereof.

[0042] In this specification, the term "on" refers not only to a case where one structure is formed directly on top of another structure, but also to a case where a third structure is interposed between the structures.

[0043] In this specification, the term "single-particle positive electrode active material" refers to a positive electrode active material consisting of 10 or less primary particles, as opposed to a spherical secondary particle positive electrode active material formed by agglomeration of tens to hundreds of primary particles produced by conventional methods. Specifically, in the present invention, the single-particle positive electrode active material may be a single particle consisting of one primary particle, or may be a secondary particle formed by agglomeration of several primary particles.

[0044] The term "primary particle" refers to the smallest particle unit that can be recognized when observing a positive electrode active material with a scanning electron microscope, and the term "secondary particle" refers to a secondary structure formed by aggregation of multiple primary particles.

[0045] In this specification, the "average cross-sectional area of ​​primary particles" refers to the average cross-sectional area of ​​one primary particle, and is a value obtained by dividing the total cross-sectional area of ​​several tens to several hundreds of primary particles present in the cross section of the positive electrode active material precursor by the number of primary particles.

[0046] As used herein, the term "average particle size (D 50)" means the particle diameter at 50% of the volume cumulative distribution of particle diameters. The average particle diameter 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., S3500 by Microtrac), measuring the difference in diffraction pattern depending on the particle size when the particles pass through a laser beam, calculating the particle size distribution, and calculating the particle diameter at 50% of the volume cumulative distribution of particle diameters in the measuring device. 50 can be measured.

[0047] In this specification, the "cross-sectional area of ​​the positive electrode active material precursor" means the total cross-sectional area of ​​the primary particles present in the cross section of the positive electrode active material precursor, the "cross-sectional area of ​​the core portion" means the total cross-sectional area of ​​the primary particles present in the core portion in the cross section of the positive electrode active material precursor, and the "cross-sectional area of ​​the shell portion" means the total cross-sectional area of ​​the primary particles present in the shell portion in the cross section of the positive electrode active material precursor.

[0048] Positive electrode active material precursor The present invention provides a positive electrode active material precursor comprising a core portion containing first primary particles and a shell portion formed on the core portion and containing second primary particles, wherein in a cross section of the positive electrode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A1) of the second primary particles to the average cross-sectional area (A2) of the first primary particles is 3.00 or more and 10.0 or less.

[0049] The larger the primary particle size of the shell portion of the positive electrode active material precursor, the more difficult it is for lithium to diffuse to the core portion when the precursor and lithium-containing raw material are mixed and sintered, resulting in defects in the core portion. Therefore, the present inventors attempted to improve the performance of the positive electrode active material by minimizing the shell portion, which is made of thick primary particles, and realizing a core portion where lithium can easily diffuse.

[0050] The cathode active material precursor according to the present invention is characterized in that the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 3.00 or more and 10.0 or less. In this case, the cathode active material precursor has the advantages of uniform particle size, excellent sphericity, and high density. Furthermore, when a mixture of the cathode active material precursor and a lithium-containing raw material is sintered, lithium easily diffuses to the core, resulting in a cathode active material with low resistance. Specifically, the (A2 / A1) ratio may be 3.00 or more, 3.50 or more, 4.00 or more, 4.10 or more, 4.20 or more, or 4.30 or more, or 4.70 or less, 4.80 or less, 4.90 or less, 5.00 or less, 6.00 or less, 7.00 or less, 8.00 or less, 9.00 or less, or 10.00 or less.

[0051] On the other hand, if the (A2 / A1) ratio is less than 3.00, lithium cannot easily diffuse to the core when the mixture of the precursor and lithium-containing raw material is sintered, resulting in defects in the core.If the (A2 / A1) ratio is more than 10.0, a significant difference in structure between the inside and outside of the positive electrode active material occurs after sintering, which may prevent the electrolyte from being smoothly introduced.

[0052] The positive electrode active material precursor according to the present invention has an average particle size (D 50 When the average particle size of the positive electrode active material precursor is within the above range, a high density positive electrode active material having a variety of sizes can be realized.

[0053] According to the present invention, the core portion may be in the form of a spherical secondary particle formed by aggregating the first primary particles. That is, the cathode active material precursor according to the present invention may have an overall spherical shape in which second primary particles are aggregated on the core portion, which is in the form of a spherical secondary particle formed by aggregating the first primary particles.

[0054] According to the present invention, the composite transition metal hydroxide may have a composition represented by the following Chemical Formula 1 or Chemical Formula 2.

[0055] [Chemical formula 1] [Ni a1 Co b1 M1 c1 M2 d1 ](OH)2

[0056] In the above Chemical Formula 1, M1 is one or more selected from Mn and Al,

[0057] M2 is one or more selected from Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca;

[0058] 0.6≦a1<1, 0 <b1≦0.4、0<c1≦0.4、0≦d1≦0.2である。

[0059] The a1 means the atomic fraction of nickel among the metal elements in the composite transition metal hydroxide having the composition represented by Chemical Formula 1, and may be 0.6≦a1<1, 0.8≦a1≦0.98, or 0.85≦a1≦0.95.

[0060] The b1 means the atomic fraction of cobalt among the metal elements in the composite transition metal hydroxide having the composition represented by Chemical Formula 1, and is 0 <b1≦0.4、0.01≦b1≦0.2、または0.01≦b1≦0.15であってよい。

[0061] The c1 means the atomic fraction of the M1 element among the metal elements in the composite transition metal hydroxide having the composition represented by Chemical Formula 1, and is 0 <c1≦0.4、0.01≦c1≦0.2、または0.01≦c1≦0.15であってよい。

[0062] The d1 means the atomic fraction of the M2 element among the metal elements in the composite transition metal hydroxide having a composition represented by Chemical Formula 1, and may be 0≦d1≦0.2, 0≦d1≦0.1, or 0≦d1≦0.05.

[0063] [Chemical formula 2] [Mn a2 Ni b2 Co c2 M d2 ](OH)2

[0064] In the above Chemical Formula 2, M is one or more selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca;

[0065] 0.5≦a2<1, 0 <b2≦0.5、0≦c2<0.5、0≦d2≦0.2である。

[0066] The a2 means the atomic fraction of manganese among the metal elements in the composite transition metal hydroxide having a composition represented by Chemical Formula 2, and may be 0.5≦a2<1, 0.6≦a2≦0.95, or 0.65≦a2≦0.9.

[0067] The b2 means the atomic fraction of nickel among the metal elements in the composite transition metal hydroxide having the composition represented by Chemical Formula 2, and is 0 <b2≦0.5、0.05≦b2≦0.4、または0.1≦b2≦0.35であってよい。

[0068] The c2 means the atomic fraction of cobalt among the metal elements in the composite transition metal hydroxide having a composition represented by Chemical Formula 2, and may be 0≦c2<0.5, 0≦c2≦0.2, or 0≦c2≦0.15.

[0069] The d2 means the atomic fraction of the M element among the metal elements in the composite transition metal hydroxide having a composition represented by Chemical Formula 2, and may be 0≦d2≦0.2, 0≦d2≦0.1, or 0≦d2≦0.05.

[0070] According to the present invention, when the composite transition metal hydroxide has a composition represented by Chemical Formula 1, in a cross section of the positive electrode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 4.60 or more and 5.00 or less, and the average particle size (D 50 ) may be 2.00 μm or more and 5.00 μm or less. In this case, when a mixture of a positive electrode active material precursor and a lithium-containing raw material is sintered, a positive electrode active material in a single particle form with a high degree of single particle formation can be easily formed, and lithium can be easily diffused to the core portion, thereby realizing a positive electrode active material with low resistance. 95 -D5) / D 50 ) value may be 1.0 or less.

[0071] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the (A2 / A1) ratio may be specifically 4.60 or more, 4.70 or less, 4.80 or less, 4.90 or less, or 5.00 or less. 50 ) may be 2.00 μm or more, 2.10 μm or more, 2.20 μm or more, 2.30 μm or more, 2.40 μm or more, 2.50 μm or more, 2.60 μm or more, 2.70 μm or more, 2.80 μm or more, 2.90 μm or more, 3.00 μm or more, 3.10 μm or more, 3.20 μm or more, or 3.30 μm or more, and may be 3.50 μm or less, 3.60 μm or less, 3.70 μm or less, 3.80 μm or less, 3.90 μm or less, 4.00 μm or less, 4.50 μm or less, or 5.00 μm or less.

[0072] According to the present invention, when the composite transition metal hydroxide has a composition represented by Chemical Formula 2, in a cross section of the positive electrode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 3.00 or more and 4.60 or less, and the average particle size (D 50) may be 9.50 μm or more and 11.00 μm or less. In this case, even though the positive electrode active material precursor is a large particle, the particle size is uniform, and it can have excellent sphericity and high density. Meanwhile, in relation to the particle size uniformity, the span (=(D 95 -D5) / D 50 ) value may be 0.65 or less.

[0073] When the composite transition metal hydroxide has a composition represented by Chemical Formula 2, the (A2 / A1) ratio may be specifically 3.00 or more, 3.50 or more, 4.00 or more, 4.10 or more, 4.20 or more, 4.30 or more, 4.31 or more, 4.32 or more, 4.33 or more, 4.34 or more, 4.35 or more, or 4.36 or more, and may be 4.53 or less, 4.54 or less, 4.55 or less, 4.56 or less, 4.57 or less, 4.58 or less, 4.59 or less, or 4.60 or less. 50 ) may be 9.50 μm or more, 9.60 μm or more, 9.70 μm or more, 9.80 μm or more, 9.90 μm or more, or 9.95 μm or more, and may be 10.00 μm or less, 10.10 μm or less, 10.20 μm or less, 10.30 μm or less, 10.40 μm or less, 10.50 μm or less, 10.60 μm or less, 10.70 μm or less, 10.80 μm or less, 10.90 μm or less, or 11.00 μm or less.

[0074] According to the present invention, the average cross-sectional area (A1) of the first primary particles is 0.0100 μm 2 ~0.0200μm 2 In this case, when the mixture of the precursor and the lithium-containing raw material is sintered, lithium can easily diffuse to the core portion, resulting in a defect-free cathode active material, and the performance of the cathode active material can be improved. Specifically, the average cross-sectional area of ​​the first primary particles is 0.0100 μm 2 More than 0.0110μm 2 More than 0.0120μm 2 Over 0.0130μm 2 or more, or 0.0140 μm 2 may be 0.0199 μm or more,2 or less, or 0.0200 μm 2 It may be the following:

[0075] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the A1 value is specifically 0.0100 μm 2 More than 0.0110μm 2 More than 0.0120μm 2 Over 0.0130μm 2 or more, or 0.0140 μm 2 It may be 0.0150 μm or more 2 Below, 0.0155μm 2 Below, 0.0160μm 2 Below, 0.0165μm 2 Below, 0.0170μm 2 Below, 0.0175μm 2 Below, 0.0180μm 2 Below, 0.0195μm 2 Below 0.0199μm 2 or less, or 0.0200 μm 2 It may be the following:

[0076] When the composite transition metal hydroxide has a composition represented by the chemical formula 2, the A1 value is specifically 0.0100 μm 2 More than 0.0110μm 2 More than 0.0120μm 2 Over 0.0130μm 2 More than 0.0140μm 2 More than 0.0150μm 2 or more, 0.0160μm 2 Over 0.0170μm 2 or more, 0.0180μm 2 or more, or 0.0190 μm 2 may be 0.0199 μm or more, 2 or less, or 0.0200 μm 2 It may be the following:

[0077] According to the present invention, the average cross-sectional area (A2) of the second primary particles is 0.0500 μm 2 ~0.1000μm2 In this case, when the mixture of the precursor and the lithium-containing raw material is sintered, a positive electrode active material in the form of a single particle or a positive electrode active material in the form of a high-density secondary particle can be easily formed. Specifically, the average cross-sectional area of ​​the second primary particles is 0.0500 μm 2 Over 0.0550μm 2 More than 0.0600μm 2 or more, or 0.0650 μm 2 It may be 0.0900 μm or more 2 Below, 0.0950μm 2 Below, 0.1000μm 2 It may be the following:

[0078] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the A2 value is specifically 0.0500 μm 2 Over 0.0550μm 2 More than 0.0600μm 2 or more, or 0.0650 μm 2 It may be 0.0700 μm or more 2 Below, 0.0750μm 2 Below, 0.0800μm 2 Below, 0.0850μm 2 Below, 0.0900μm 2 Below, 0.0950μm 2 Below, 0.1000μm 2 It may be the following:

[0079] When the composite transition metal hydroxide has a composition represented by the chemical formula 2, the A2 value is specifically 0.0500 μm 2 Over 0.0550μm 2 More than 0.0600μm 2 More than 0.0650μm 2 More than 0.0700μm 2 Over 0.0750μm 2 More than 0.0800μm 2 Over 0.0810μm 2 or more, 0.0820μm 2 or more, 0.0830μm 2More than 0.0840μm 2 It may be 0.0900 μm or more 2 Below, 0.0950μm 2 Below, 0.1000μm 2 It may be the following:

[0080] According to the present invention, in the cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion may be 11.00% to 30.00%. That is, in the cross section of the positive electrode active material precursor, the value calculated by the following formula 1 may be 12.00% to 30.00%. In this case, when a positive electrode active material is produced using the precursor, a positive electrode active material in the form of a single particle with no defects in the core portion or a positive electrode active material in the form of a high-density secondary particle may be produced. Specifically, the value calculated by the formula 1 may be 11.00% or more, 11.10% or more, 11.20% or more, 11.30% or more, 11.40% or more, or 11.50% or more, or 16.50% or less, 17.00% or less, 18.00% or less, 19.00% or less, 20.00% or less, 25.00% or less, or 30.00% or less.

[0081]

number

[0082] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the value according to Formula 1 may be specifically 11.00% or more, 11.10% or more, 11.20% or more, 11.30% or more, 11.40% or more, 11.50% or more, 12.00% or more, 13.00% or more, or 14.00% or more, and may be 14.50% or less, 15.00% or less, 15.50% or less, 16.00% or less, 16.50% or less, 17.00% or less, 18.00% or less, 19.00% or less, 20.00% or less, 25.00% or less, or 30.00% or less.

[0083] When the composite transition metal hydroxide has a composition represented by Chemical Formula 2, the value according to Formula 1 may be specifically 11.00% or more, 11.10% or more, 11.20% or more, 11.30% or more, 11.40% or more, or 11.50% or more, and may be 16.50% or less, 17.00% or less, 18.00% or less, 19.00% or less, 20.00% or less, 25.00% or less, or 30.00% or less.

[0084] According to the present invention, in the cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion may be 2.00% to 7.00%. That is, in the cross section of the positive electrode active material precursor, the value obtained by the following formula 2 may be 2.00% to 5.00%. In this case, when a positive electrode active material is produced using the precursor, a high-density positive electrode active material can be produced even at a low firing temperature. Specifically, the value obtained by the formula 2 may be 2.00% or more, 3.00% or more, 4.00% or more, 4.10% or more, 4.20% or more, 4.30% or more, 4.40% or more, or 4.50% or more, or may be 6.30% or less, 6.40% or less, 6.50% or less, 6.60% or less, 6.70% or less, 6.80% or less, 6.90% or less, or 7.00% or less.

[0085]

number

[0086] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the value according to Formula 2 may be specifically 2.00% or more, 3.00% or more, 4.00% or more, 4.10% or more, 4.20% or more, 4.30% or more, 4.40%, or 4.50% or more, and may be 4.60% or less, 4.70% or less, 4.80% or less, 4.90% or less, 5.00% or less, 5.10% or less, or 5.20% or less. %, 5.20% or less, 5.30% or less, 5.40% or less, 5.50% or less, 5.60% or less, 5.70% or less, 5.80% or less, 5.90% or less, 6.00% or less, 6.10% or less, 6.20% or less, 6.30% or less, 6.40% or less, 6.50% or less, 6.60% or less, 6.70% or less, 6.80% or less, 6.90% or less, or 7.00% or less.

[0087] When the composite transition metal hydroxide has a composition represented by Chemical Formula 2, the value according to Formula 2 is specifically 2.00% or more, 3.00% or more, 4.00% or more, 4.10% or more, 4.20% or more, 4.30% or more, 4.40%, 4.50% or more, 4.60% or more, 4.70% or more, 4.80% or more, 4.90% or more, 5.00% or more, 5.10% or more or more, 5.20% or more, 5.30% or more, 5.40% or more, 5.50% or more, 5.60% or more, 5.70% or more, 5.80% or more, 5.90% or more, or 6.00% or more, and may be 6.30% or less, 6.40% or less, 6.50% or less, 6.60% or less, 6.70% or less, 6.80% or less, 6.90% or less, or 7.00% or less.

[0088] According to the present invention, in a cross section of the positive electrode active material precursor, the difference (CS) between the percentage (C) of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion and the percentage (S) of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion may be 5.00% to 28.00%. In this case, when a mixture of the positive electrode active material precursor and a lithium-containing raw material is sintered, a positive electrode active material in a single particle form with a high degree of single particleization or a positive electrode active material in a secondary particle form with high density can be easily formed, and lithium can easily diffuse into the core portion, resulting in a positive electrode active material with low resistance. Specifically, the (CS) value may be 5.00% or more, 5.10% or more, or 5.20% or more, and may be 10.00% or less, 11.00% or less, 12.00% or less, 13.00% or less, 14.00% or less, 15.00% or less, 20.00% or less, 25.00% or less, or 28.00% or less.

[0089] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the (CS) value may be, specifically, 5.00% or more, 5.10% or more, 5.20% or more, 5.50% or more, 6.00% or more, 7.00% or more, 8.00% or more, 9.00% or more, or 9.50% or more, and may be 10.00% or less, 11.00% or less, 12.00% or less, 13.00% or less, 14.00% or less, 15.00% or less, 20.00% or less, 25.00% or less, or 28.00% or less.

[0090] When the composite transition metal hydroxide has a composition represented by Chemical Formula 2, the (CS) value may be, specifically, 5.00% or more, 5.10% or more, or 5.20% or more, and may be 10.00% or less, 11.00% or less, 12.00% or less, 13.00% or less, 14.00% or less, 15.00% or less, 20.00% or less, 25.00% or less, or 28.00% or less.

[0091] According to the present invention, in a cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​the core portion relative to the cross-sectional area of ​​the positive electrode active material precursor may be 5.00% to 50.00%. That is, in a cross section of the positive electrode active material precursor, the value calculated by the following formula 3 may be 5.00% to 50.00%. In this case, when a mixture of the positive electrode active material precursor and a lithium-containing raw material is sintered, a positive electrode active material in the form of a single particle having a high degree of single particleization or a positive electrode active material in the form of a secondary particle having a high density may be easily formed. Specifically, the value calculated by the formula 3 may be 5.00% or more, 5.50% or more, 6.00% or more, 6.10% or more, 6.20% or more, or 6.30% or more, or 32.00% or less, 35.00% or less, 40.00% or less, 45.00% or less, or 50.00% or less.

[0092]

number

[0093] When the composite transition metal hydroxide has a composition represented by Chemical Formula 1, the value according to Formula 3 may be, specifically, 5.00% or more, 5.50% or more, 6.00% or more, 6.10% or more, 6.20% or more, 6.30% or more, 6.50% or more, 7.00% or more, 10.00% or more, 15.00% or more, 20.00% or more, 25.00% or more, or 30.00% or more, and may be 32.00% or less, 35.00% or less, 40.00% or less, 45.00% or less, or 50.00% or less.

[0094] When the composite transition metal hydroxide has a composition represented by Chemical Formula 2, the value according to Formula 3 may be specifically 5.00% or more, 5.50% or more, 6.00% or more, 6.10% or more, 6.20% or more, or 6.30% or more, and may be 10.00% or less, 15.00% or less, 20.00% or less, 25.00% or less, 30.00% or less, 32.00% or less, 35.00% or less, 40.00% or less, 45.00% or less, or 50.00% or less.

[0095] Method for producing a positive electrode active material precursor (1) The present invention also provides a method (1) for producing the positive electrode active material precursor.

[0096] The present invention relates to a method for producing a cathode active material precursor (1) using a reactor connected to a continuous mill. The method includes the steps of: (S1) introducing a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution into the reactor, forming cathode active material precursor seeds by coprecipitation while simultaneously operating the continuous mill, discharging the cathode active material precursor seeds from the reactor to the continuous mill, and then re-introducing the seeds from the continuous mill back into the reactor; and (S2) stopping the operation of the continuous mill and growing cathode active material precursor particles in the reactor. Step (S1) may be performed while gradually decreasing the pH, and step (S2) may be performed while gradually increasing the pH. Thus, the present invention relates to a method for producing a cathode active material precursor using a reactor connected to a continuous mill. By appropriately adjusting the pH, the present invention can not only increase the production efficiency of the cathode active material precursor but also easily provide the cathode active material precursor.

[0097] The method (1) for producing a positive electrode active material precursor is suitable for producing a positive electrode active material precursor containing a composite transition metal hydroxide having a composition represented by Chemical Formula 1 above.

[0098] (S1) Step The step (S1) is a step of repeatedly introducing a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution into a reactor, forming a cathode active material precursor seed by a coprecipitation reaction, operating a continuous pulverizer at the same time, discharging the cathode active material precursor seed from the reactor to the continuous pulverizer, and then re-introducing the cathode active material precursor seed from the continuous pulverizer into the reactor.

[0099] 1 is a schematic diagram showing a reaction apparatus that can be used in the method for producing a cathode active material precursor of the present invention. The method for producing a cathode active material precursor of the present invention uses a reaction apparatus that is connected to a reactor 100 and a continuous grinder 200.

[0100] In step (S1), a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution are introduced into a reactor 100, and positive electrode active material precursor seeds are formed in the reactor 100.

[0101] The reactor 100 may be any type of reactor, such as a batch type reactor, a continuous stirred tank reactor (CSTR), or a continuous filtered tank reactor (CFTR).

[0102] More specifically, a reactor equipped with a filtration device inside the reactor, such as a continuous filtered tank reactor (CFTR), may be used, in which the transition metal-containing solution, ammonium ion-containing solution, and basic aqueous solution may be continuously introduced.

[0103] The cathode active material precursor seeds formed in step (S1) may refer to seeds formed by agglomeration of primary particle-form nuclei of cathode active material precursor particles, which are generated when a coprecipitation reaction is initiated by introducing a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution. The cathode active material precursor seeds are then fed into a reactor after passing through a continuous mill, as described below, where they aggregate (through a particle growth process) to form cathode active material precursor cores.

[0104] The transition metal-containing solution may contain cations of one or more metals selected from nickel (Ni), manganese (Mn), cobalt (Co), tungsten (W), molybdenum (Mo), chromium (Cr), and aluminum (Al). The metal ion-containing solution may contain acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, or oxyhydroxides of the metals, and is not particularly limited as long as it is soluble in water.

[0105] For example, the cobalt (Co) may be included as Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, CoSO4, or Co(SO4)2·7H2O, or a mixture of any one or more of these. The nickel (Ni) may be included as Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiCO2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, fatty acid nickel salt, or nickel halide, or a mixture of any one or more of these. The manganese (Mn) may be included in the form of manganese oxides such as MnO, MnO, and MnO; manganese salts such as MnCO, Mn(NO), MnSO, ​​manganese acetate, manganese dicarboxylate, manganese citrate, and manganese fatty acid salt; oxyhydroxide, manganese chloride, etc., and any one or a mixture of two or more of these may be used.

[0106] Meanwhile, when the final precursor further contains a second metal element (M) other than nickel (Ni), manganese (Mn), cobalt (Co), tungsten (W), molybdenum (Mo), chromium (Cr), and aluminum (Al) (e.g., M is one or more elements selected from Zr, Ti, Mg, Ta, and Nb), the second metal element-containing source material may be selectively added during the preparation of the transition metal-containing solution. Examples of the second metal element-containing source material include acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, and oxyhydroxides containing the second metal element, and one of these may be used alone or a mixture of two or more may be used. For example, when the second metal element is Zr, zirconium oxide may be used.

[0107] The ammonium ion-containing solution may contain one or more selected from NHOH, (NH)SO, NHNO, NHCl, CHCOONH, and NHCO. The solvent may be water or a mixture of water and an organic solvent (e.g., alcohol) that is uniformly miscible with water.

[0108] The basic aqueous solution may contain one or more selected from the group consisting of alkali metal hydrates, alkali metal hydroxides, alkaline earth metal hydrates, and alkaline earth metal hydroxides. For example, the basic aqueous solution may contain NaOH, KOH, or Ca(OH)2, and the solvent may be water or a mixture of water and an organic solvent (e.g., alcohol) that is uniformly miscible with water.

[0109] According to the present invention, the step (S1) may be carried out while gradually decreasing the pH within the range of pH 12.6 to 11.2, which may be advantageous for seed formation. Meanwhile, the pH may be adjusted with the basic aqueous solution.

[0110] The step (S1) includes a step of forming a cathode active material precursor seed while simultaneously operating a continuous pulverizer, discharging the cathode active material precursor seed from a reactor to the continuous pulverizer, and then re-introducing the cathode active material precursor seed from the continuous pulverizer into the reactor, and repeating this step. This makes it possible to prevent the cathode active material precursor seed from concentrating in the reactor and increasing in particle size.

[0111] The cathode active material precursor seeds formed in step (S1) are not concentrated in the reactor, but are pulverized in a continuous pulverizer and then re-introduced into the reactor.

[0112] If the reaction continues after the reaction solution is introduced into the reactor, particle agglomeration occurs, and this tends to occur severely, particularly until the reaction progress rate in the reactor reaches 30%. In the present invention, before the reaction progresses significantly in the reactor and particle agglomeration occurs, the positive electrode active material precursor seeds are introduced into a continuous grinder to be broken into smaller sizes, thereby suppressing agglomeration and controlling the particle size uniformly.

[0113] Therefore, in the present invention, the cathode active material precursor seeds that are re-introduced into the reactor after the above process have a narrow particle size distribution and uniform characteristics. Therefore, the small particle size and large seed contact area not only improve the production efficiency of the cathode active material precursor, but also result in the provision of a cathode active material precursor with a uniform particle size.

[0114] The rate at which the positive electrode active material precursor seeds are discharged from the reactor to the continuous pulverizer and the rate at which the positive electrode active material precursor seeds are re-introduced from the continuous pulverizer to the reactor may each independently be equal to or greater than [the capacity (L) of the reactor 100 × 6] / [hr], specifically, equal to or greater than [the capacity (L) of the reactor 100 × 8] / [hr], equal to or greater than [the capacity (L) of the reactor 100 × 10] / [hr], or equal to or greater than [the capacity (L) of the reactor 100 × 12] / [hr]. In this case, the effect of pulverizing the seeds into small sizes and uniformly controlling the particle size can be sufficiently achieved.

[0115] The method for producing a positive electrode active material precursor according to the present invention further comprises the steps (S1) and (S2) between the steps (S1) and (S3). + The method may further include a step of repeatedly operating the continuous pulverizer while feeding a reaction solution containing a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution into the reactor to grow positive electrode active material precursor particles, discharging the positive electrode active material precursor particles from the reactor to the continuous pulverizer, and then feeding the positive electrode active material precursor particles from the continuous pulverizer back into the reactor. + ) step may be carried out at a gradually increasing pH.

[0116] The above (S1 +In step (S1), the transition metal-containing solution, ammonium ion-containing solution, basic aqueous solution, and continuous grinder are introduced as in step (S1). + ) steps differ only in pH conditions.

[0117] The above (S1 + The precipitation step may be carried out by gradually increasing the pH within the range of 11.2 to 12.6. In this case, thin primary particles may be formed at a pH of 11.2 to 11.8, and thick primary particles may be formed at a pH of 11.8 to 12.6. The pH may be adjusted with the basic aqueous solution.

[0118] (S2) Step The step (S2) is a step of stopping the operation of the continuous pulverizer and growing the positive electrode active material precursor particles in the reactor.

[0119] This is a step of manufacturing a cathode active material precursor using cathode active material precursor seeds of uniform particle size obtained in a reactor through step (S1). To prevent the seeds from being discharged into a continuous mill and continuously milled, the operation of the continuous mill is stopped after step (S1) is fully performed, and a reaction solution containing a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution is introduced into the reactor to grow cathode active material precursor particles.

[0120] According to the present invention, step (S2) may be performed by gradually increasing the pH within the range of pH 11.2 to 12.6. In this case, thin primary particles are formed at pH 11.2 to 11.8, and thick primary particles are formed at pH 11.8 to 12.6, thereby producing the cathode active material precursor according to the present invention. Meanwhile, the pH can be adjusted by the basic aqueous solution.

[0121] Method for producing a positive electrode active material precursor (2) The present invention also provides a method (2) for producing the positive electrode active material precursor.

[0122] The method (2) for producing a cathode active material precursor according to the present invention includes the steps of (S1') introducing a transition metal-containing solution and a basic aqueous solution into a reactor and forming cathode active material precursor seeds by a coprecipitation reaction, and (S2') introducing a transition metal-containing solution and a basic aqueous solution into the reactor containing the cathode active material precursor seeds and growing cathode active material precursor particles by a coprecipitation reaction. Step (S1') may be performed by gradually decreasing the pH from pH 12.0 or higher to pH 9.0-11.0 and then maintaining the pH within the range of 9.0-11.0. Step (S2') may be performed by gradually decreasing the pH from pH 11.5-11.7 to pH 9.0-11.0 and then maintaining the pH within the range of 9.0-11.0. Thus, the method for producing a cathode active material according to the present invention can easily provide the cathode active material precursor according to the present invention by appropriately adjusting the addition or non-addition of an ammonium ion-containing solution and the pH.

[0123] The method (2) for producing a positive electrode active material precursor is a method suitable for producing a positive electrode active material precursor containing a composite transition metal hydroxide having a composition represented by Chemical Formula 2 above.

[0124] (S1') Step Step (S1') is a step of introducing a transition metal-containing solution and a basic aqueous solution into a reactor and co-precipitation-reacting them to form a cathode active material precursor seed. The reactor may be a continuous filtered tank reactor (CFTR). In this case, the transition metal-containing solution and the basic aqueous solution may be continuously introduced.

[0125] The cathode active material precursor seeds formed in step (S1') may refer to seeds formed by agglomeration of primary particle-shaped nuclei of cathode active material precursor particles that are generated as a coprecipitation reaction begins when a transition metal-containing solution and a basic aqueous solution are introduced. During the coprecipitation reaction in step (S1'), no ammonium ion-containing solution is introduced.

[0126] The transition metal-containing solution may contain cations of one or more metals selected from nickel (Ni), manganese (Mn), cobalt (Co), tungsten (W), molybdenum (Mo), chromium (Cr), and aluminum (Al). The metal ion-containing solution may contain acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, or oxyhydroxides of the metals, and is not particularly limited as long as it is soluble in water.

[0127] For example, the cobalt (Co) may be included as Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, CoSO4, or Co(SO4)2·7H2O, or a mixture of any one or more of these. The nickel (Ni) may be included as Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiCO2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, fatty acid nickel salt, or nickel halide, or a mixture of any one or more of these. The manganese (Mn) may be included in the form of manganese oxides such as MnO, MnO, and MnO; manganese salts such as MnCO, Mn(NO), MnSO, ​​manganese acetate, manganese dicarboxylate, manganese citrate, and manganese fatty acid salt; oxyhydroxide, manganese chloride, etc., and any one or a mixture of two or more of these may be used.

[0128] Meanwhile, when the final precursor further contains a second metal element (M) other than nickel (Ni), manganese (Mn), cobalt (Co), tungsten (W), molybdenum (Mo), chromium (Cr), and aluminum (Al) (e.g., M is one or more elements selected from Zr, Ti, Mg, Ta, and Nb), the second metal element-containing source material may be selectively added during the preparation of the transition metal-containing solution. Examples of the second metal element-containing source material include acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, and oxyhydroxides containing the second metal element, and one of these may be used alone or a mixture of two or more may be used. For example, when the second metal element is Zr, zirconium oxide may be used.

[0129] The basic aqueous solution may contain one or more selected from the group consisting of alkali metal hydrates, alkali metal hydroxides, alkaline earth metal hydrates, and alkaline earth metal hydroxides. For example, the basic aqueous solution may contain NaOH, KOH, or Ca(OH)2, and the solvent may be water or a mixture of water and an organic solvent (e.g., alcohol) that is uniformly miscible with water.

[0130] According to the present invention, step (S1') may be performed by gradually decreasing the pH from pH 12.0 or higher to pH 9.0-11.0 to generate seeds, and then maintaining the pH within the range of pH 9.0-11.0. This may be advantageous for seed formation. On the other hand, if the pH is rapidly decreased at the beginning of the reaction, the precursor growth reaction may proceed without sufficient seeds being formed, resulting in rapid particle size growth and the generation of precursors of unintended quality. On the other hand, the pH can be adjusted using the basic aqueous solution.

[0131] According to the present invention, step (S1') may be performed in an oxidizing atmosphere, which may result in the formation of thin primary particles with appropriate voids in the core, thereby resulting in a high density of the active material when a cathode active material is finally prepared using the cathode active material precursor.

[0132] (S2') Step The step (S2') is a step of growing positive electrode active material precursor particles in the reactor.

[0133] This is a step of producing a cathode active material precursor using the cathode active material precursor seeds of uniform particle size obtained in the reactor through step (S1'), in which a transition metal-containing solution and a basic aqueous solution are introduced into the reactor and a co-precipitation reaction occurs to grow the cathode active material precursor particles. In step (S1'), the ammonium ion-containing solution is not introduced during the co-precipitation reaction.

[0134] According to the present invention, step (S2') may be performed by gradually decreasing the pH from pH 11.5-11.7 to pH 9.0-11.0 and then maintaining the pH within the range of pH 9.0-11.0. In this case, a growth reaction of the precursor seeds generated in step (S1') proceeds, thereby producing the cathode active material precursor according to the present invention. On the other hand, if the final pH is lower than 9.0-11.0, there is a problem that a large amount of fine powder is formed, and if the final pH is higher than 9.0-11.0, there is a problem that the primary particles aggregate together, making it impossible to produce the cathode active material precursor according to the present invention. On the other hand, the pH can be adjusted using the basic aqueous solution.

[0135] According to the present invention, the (S2') step may be carried out under an oxidizing atmosphere for optimal primary particle shape and control of Mn impurities.

[0136] The ammonium ion-containing solution may contain one or more selected from NHOH, (NH)SO, NHNO, NHCl, CHCOONH, and NHCO. The solvent may be water or a mixture of water and an organic solvent (e.g., alcohol) that is uniformly miscible with water.

[0137] positive electrode active material The present invention provides a cathode that is a calcined product of a mixture of the cathode active material precursor and a lithium source material. That is, the cathode active material can be prepared by mixing the cathode active material precursor according to the present invention with a lithium source material and then calcining the mixture. The cathode active material can be a cathode active material with high energy density. Furthermore, the cathode active material can be prepared from the cathode active material precursor according to the present invention, and can be free of internal defects and have low resistance. Meanwhile, when the cathode active material precursor is a high-nickel NCM-based cathode active material precursor, the cathode active material can be a single-particle cathode active material.

[0138] Examples of the lithium source material include lithium-containing carbonates (e.g., lithium carbonate, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH·H2O)), hydroxides (e.g., lithium hydroxide, etc.), nitrates (e.g., lithium nitrate (LiNO3), etc.), and chlorides (e.g., lithium chloride (LiCl)), and any one of these can be used alone or in combination of two or more.

[0139] Meanwhile, the positive electrode active material precursor and the lithium source material may be mixed by solid-phase mixing, and the mixing ratio of the positive electrode active material precursor and the lithium source material may be determined within a range that satisfies the atomic fraction of each component in the final positive electrode active material. For example, the positive electrode active material precursor and the lithium source material may be mixed in amounts such that the molar ratio of transition metal to Li contained in the positive electrode active material precursor is 1:0.9 to 1:1.2, preferably 1:0.98 to 1:1.1. When the positive electrode active material precursor and the lithium source material are mixed within the above range, a positive electrode active material exhibiting excellent capacity characteristics can be produced.

[0140] The firing may be carried out at a temperature of 600°C to 1000°C, preferably 700°C to 900°C, and the firing time may be, but is not limited to, 5 hours to 30 hours, preferably 10 hours to 20 hours.

[0141] For example, the cathode active material according to the present invention can be prepared by primarily mixing the cathode active material precursor and a lithium source material so that the ratio of the total moles of transition metals contained in the cathode active material precursor to the moles of lithium contained in the lithium source material is 1:0.95 to 1:1.00, and then primarily firing the mixture at 850°C to 1000°C for 5 to 10 hours to prepare a primary fired product. Then, the primary fired product and the lithium source material can be secondarily mixed so that the ratio of the total moles of transition metals contained in the cathode active material precursor to the moles of lithium contained in the lithium source material is 1:0.02 to 1:0.07, and then secondary firing the mixture at 800°C to 850°C for 5 to 15 hours. The resulting cathode active material can be in the form of a single particle.

[0142] The positive electrode active material may have a composition represented by the following Chemical Formula 3 or 4:

[0143] [Chemical formula 3] Li x1 [Ni a3 Co b3 M1 c3 M2 d3 ]O 2-

[0144] In the above Chemical Formula 3, M1 is one or more selected from Mn and Al, M2 is one or more selected from Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; 0.9≦x1≦1.2, 0.6≦a3<1, 0 <b3≦0.4、0<c3≦0.4、0≦d4≦0.2である。

[0145] The a3 means the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide having a composition represented by Chemical Formula 3, and may be 0.6≦a3<1, 0.8≦a3≦0.98, or 0.85≦a3≦0.95.

[0146] The b3 represents the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide having the composition represented by Chemical Formula 3, and is 0 <b3≦0.4、0.01≦b3≦0.2、または0.01≦b3≦0.15であってよい。

[0147] The c3 means the atomic fraction of the M1 element among the metal elements in the lithium composite transition metal oxide having the composition represented by Chemical Formula 3, and is 0 <c3≦0.4、0.01≦c3≦0.2、または0.01≦c3≦0.15であってよい。

[0148] The d3 means the atomic fraction of the M2 element among the metal elements in the lithium composite transition metal oxide having a composition represented by Chemical Formula 3, and may be 0≦d3≦0.2, 0≦d3≦0.1, or 0≦d3≦0.05.

[0149] [Chemical formula 4] Li x2 [Mn a4 Ni b4 Co c4 M d4 ]O2

[0150] In the above Chemical Formula 2, M is one or more selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; 0.9≦x2≦1.2, 0.5≦a4<1, 0 <b4≦0.5、0≦c4<0.5、0≦d4≦0.2である。

[0151] The a4 represents the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide having a composition represented by Chemical Formula 4, and may be 0.5≦a4<1, 0.6≦a4≦0.95, or 0.65≦a4≦0.9.

[0152] The b4 represents the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide having the composition represented by Chemical Formula 4, and is 0 <b4≦0.5、0.05≦b4≦0.4、または0.1≦b4≦0.35であってよい。

[0153] The c4 represents the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide having a composition represented by Chemical Formula 4, and may be 0≦c4<0.5, 0≦c4≦0.2, or 0≦c4≦0.15.

[0154] The d4 means the atomic fraction of the M element among the metal elements in the lithium composite transition metal oxide having a composition represented by Chemical Formula 4, and may be 0≦d4≦0.2, 0≦d4≦0.1, or 0≦d4≦0.05.

[0155] When the positive electrode active material has the composition represented by Formula 3, the positive electrode active material may be a single particle type positive electrode active material. When the positive electrode active material is a single particle type positive electrode active material, the average particle size (D 50 ) may be 1.0 μm to 6.0 μm, specifically, 1.0 μm or more, 2.0 μm or more, 3.0 μm or more, or 4.0 μm or more, and may be 5.0 μm or less, or 6.0 μm or less, and may have an angular shape rather than a spherical shape.

[0156] When the positive electrode active material has the composition represented by Formula 4, the positive electrode active material may be a positive electrode active material in the form of secondary particles. When the positive electrode active material is a positive electrode active material in the form of secondary particles, the average particle size (D 50) may be 9.0 μm to 12.0 μm, specifically, 9.0 μm or more, 9.1 μm or more, 9.2 μm or more, 9.3 μm or more, 9.4 μm or more, 9.5 μm or more, 9.6 μm or more, 9.7 μm or more, 9.8 μm or more, or 9.9 μm or more, and may be 10.0 μm or less, 10.5 μm or less, 11.0 μm or less, 11.5 μm or less, or 12.0 μm or less, and may be spherical.

[0157] positive electrode The present invention provides a positive electrode containing the positive electrode active material.

[0158] The 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 active material.

[0159] The positive electrode current collector may contain a highly conductive metal, and is not particularly limited as long as it is easily adhered to the positive electrode active material layer and is non-reactive within the battery voltage range. Examples of the positive electrode current collector include stainless steel, aluminum, nickel, titanium, and calcined carbon, as well as aluminum or stainless steel whose surfaces have been surface-treated with carbon, nickel, titanium, silver, or the like. The positive electrode current collector typically has a thickness of 3 μm to 500 μm, and the adhesion of the positive electrode active material may be enhanced by forming fine irregularities on the surface of the current collector. The positive electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0160] The positive electrode active material layer may optionally contain a conductive material and a binder in addition to the positive electrode active material. In this case, the positive electrode active material may be contained in an amount of 80 wt% to 99 wt%, more specifically 85 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer. When the amount is within this range, excellent capacity characteristics can be exhibited.

[0161] The conductive material is used to impart conductivity to the electrode and can be any material that does not cause chemical changes in the resulting battery and has electronic conductivity. Specific examples include graphite such as natural graphite and artificial graphite; carbon-based materials such as carbon black, acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber 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; and conductive polymers such as polyphenylene derivatives. One of these may be used alone, or two or more may be used in combination. The conductive material may be contained in an amount of 0.1 wt % to 15 wt % based on the total weight of the positive electrode active material layer.

[0162] The binder functions to improve adhesion between particles of the positive electrode active material and between the positive electrode active material and the current collector. Specific examples of the binder include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethylmethacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, polymers in which hydrogen atoms in these polymers are substituted with Li, Na, or Ca, or various copolymers thereof. These may be used alone or in combination. The binder may be contained in an amount of 0.1 wt % to 15 wt % based on the total weight of the positive electrode active material layer.

[0163] The positive electrode may be manufactured by a conventional method for manufacturing a positive electrode, except for using the positive electrode active material. Specifically, the positive electrode may be manufactured by applying a positive electrode active material layer-forming composition, which is manufactured by dissolving or dispersing the positive electrode active material and, if necessary, selectively a binder, a conductive material, and a dispersant in a solvent, onto a positive electrode current collector, followed by drying and rolling, or by casting the positive electrode active material layer-forming composition onto another support, peeling it from the support, and laminating the resulting film onto the positive electrode current collector.

[0164] The solvent may be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, or water, and may be used alone or in combination. The amount of solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant, and to provide a viscosity that allows excellent thickness uniformity during subsequent coating for positive electrode fabrication, taking into consideration the coating thickness of the slurry and the production yield.

[0165] Lithium secondary battery The present invention provides a lithium secondary battery including the positive electrode, a negative electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte.

[0166] The lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0167] The negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0168] The negative electrode current collector is not particularly limited as long as it does not cause chemical changes in the battery and has high conductivity. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surfaces treated with carbon, nickel, titanium, silver, or the like, and aluminum-cadmium alloys may be used. The negative electrode current collector typically has a thickness of 3 μm to 500 μm, and, like the positive electrode current collector, the surface of the current collector may be formed with fine irregularities to strengthen the binding force of the negative electrode active material. The negative electrode current collector may be used in various forms, such as a film, sheet, foil, mesh, porous material, foam, or nonwoven fabric.

[0169] The negative electrode active material layer may optionally contain a binder and a conductive material in addition to the negative electrode active material.

[0170] The negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, and Al alloys; and SiO. βExamples of the negative electrode active material include metal oxides capable of doping and dedoping lithium, such as SnO2, vanadium oxide, and lithium vanadium oxide (0<β<2); and composites containing the metallic compounds and carbonaceous materials, such as Si-C composites and Sn-C composites. A mixture of two or more of these materials can be used. A thin film of metallic lithium can also be used as the negative electrode active material. Both low-crystalline carbon and high-crystalline carbon can be used as the carbon material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, while representative examples of high-crystalline carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, mesocarbon microbeads, mesophase pitches, and high-temperature-fired carbon such as petroleum or coal tar pitch-derived cokes. The negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0171] The binder in the negative electrode active material layer is a component that aids in bonding between the conductive material, active material, and 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, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0172] The conductive material in the negative electrode active material layer is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt % or less, preferably 5 wt % or less, based on the total weight of the negative electrode active material layer. The conductive material is not particularly limited as long as it does not cause chemical changes in the battery and is conductive. Examples of such conductive materials include graphite such as natural graphite and artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber and metal fiber; metal powders such as carbon fluoride, aluminum, and nickel powder; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0173] The negative electrode may be produced by applying a composition for forming a negative electrode active material layer, which is prepared by dissolving or 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 composition. Alternatively, the negative electrode may be produced by casting the composition for forming a negative electrode active material layer onto a separate support, peeling it off from the support, and laminating the resulting film onto the negative electrode current collector.

[0174] The separator separates the negative electrode and the positive electrode and provides a path for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without particular limitations. In particular, separators with low resistance to electrolyte ion movement and excellent electrolyte impregnation capacity are preferred. Specifically, porous polymer films, such as those made of polyolefin-based polymers such as ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers, or laminate structures of two or more layers thereof, can be used. Conventional porous nonwoven fabrics, such as nonwoven fabrics made of high-melting-point glass fibers or polyethylene terephthalate fibers, can also be used. To ensure heat resistance or mechanical strength, coated separators containing ceramic components or polymeric materials can also be used, and they can be selectively used in single-layer or multi-layer structures.

[0175] Examples of the electrolyte include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc. that can be used in manufacturing lithium secondary batteries. As a specific example, the electrolyte may include an organic solvent and a lithium salt.

[0176] The organic solvent may be any solvent capable of acting as a medium for the movement of ions involved in the electrochemical reaction of the battery. Specific examples of the organic solvent include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether and tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylenecarbonate (EC), and propylene carbonate. Examples of solvents that can be used include carbonate-based solvents such as ethylene carbonate (PC), alcohol-based solvents such as ethyl alcohol and isopropyl alcohol, nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, which may contain a double-bonded aromatic ring or an ether bond), amides such as dimethylformamide, dioxolanes such as 1,3-dioxolane, and sulfolanes. Among these, carbonate-based solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) with high ionic conductivity and a high dielectric constant, which can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferred.

[0177] The lithium salt can be any compound that can provide lithium ions used in lithium secondary batteries without any particular limitation. Specifically, the anion of the lithium salt can be 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. The concentration of the lithium salt is preferably within the range of 0.1 M to 2.0 M. When the lithium salt concentration is within the above range, the electrolyte has appropriate conductivity and viscosity, thereby exhibiting excellent electrolyte performance and allowing lithium ions to migrate effectively.

[0178] In addition to the constituent components of the electrolyte, the electrolyte may further contain one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinoneimine 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 battery life characteristics, suppressing battery capacity reduction, improving battery discharge capacity, etc. In this case, the additives may be contained in an amount of 0.1 wt % to 5 wt % based on the total weight of the electrolyte.

[0179] The lithium secondary battery including the positive electrode active material according to the present invention has excellent capacity characteristics, initial efficiency, resistance characteristics, and life characteristics, and is therefore useful in the fields of portable devices such as mobile phones, notebook computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0180] The external shape of the lithium secondary battery of the present invention is not particularly limited, and may be a cylindrical shape using a can, a square shape, a pouch shape, a coin shape, or the like.

[0181] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for small devices, but also as a unit battery in a medium- to large-sized battery module containing a large number of battery cells.

[0182] This provides a battery module including the lithium secondary battery as a unit cell, and a battery pack including the same.

[0183] The battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and an electric vehicle (PHEV), including a plug-in hybrid electric vehicle; or a power storage system.

[0184] Although the present invention may be embodied in various different forms, it is not intended to be limited to the embodiments set forth herein, and the present invention is not limited to the embodiments set forth herein.

[0185] Example 1 NiSO4, CoSO4, and MnSO4 were added to distilled water in amounts such that the molar ratio of Ni:Co:Mn was 88.5:3.5:8.0 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a 7.96 M NaOH aqueous solution and a 5.08 M NH4OH aqueous solution were prepared.

[0186] As shown in FIG. 1, the vessel containing the transition metal-containing solution, the vessel containing the NaOH aqueous solution, and the vessel containing the NH 4 OH aqueous solution were each connected to a 100 L reactor.

[0187] After 28.59 L of deionized water, 0.035 L of the aqueous NaOH solution, and 0.216 L of the aqueous NH4OH solution were charged into the reactor, nitrogen gas was purged into the reactor to remove dissolved oxygen in the water and create a non-oxidizing atmosphere inside the reactor.

[0188] Thereafter, the transition metal-containing solution and the NH4OH aqueous solution were continuously added to the reactor at a rate of 7.26 L / hr and 1.03 L / hr, respectively. At the same time, the NaOH aqueous solution was added in conjunction with a pH sensor to gradually decrease the pH as shown in FIG. 2(A). A co-precipitation reaction was carried out for 1.5 hours to form a cathode active material precursor seed. At the same time, the continuous pulverizer was operated, and the cathode active material precursor seed was discharged from the reactor to the continuous pulverizer at a rate of 1000 L / hr ([reactor volume × 10] / [hr]), and then re-added from the continuous pulverizer to the reactor at a rate of 1000 L / hr ([reactor volume × 10] / [hr]). This process was repeated.

[0189] Thereafter, the transition metal-containing solution and the NH4OH aqueous solution were continuously added to the reactor at a rate of 7.26 L / hr and 1.03 L / hr, respectively. At the same time, the NaOH aqueous solution was added in conjunction with a pH sensor to gradually increase the pH as shown in FIG. 2(A). A co-precipitation reaction was carried out for 4.5 hours to grow positive electrode active material precursor particles. At the same time, the continuous mill was operated, and the positive electrode active material precursor seeds were discharged from the reactor to the continuous mill at a rate of 1000 L / hr ([reactor volume × 10] / [hr]) and then re-added from the continuous mill to the reactor at a rate of 1000 L / hr ([reactor volume × 10] / [hr]). This process was repeated.

[0190] Thereafter, the operation of the continuous mill was stopped, and the transition metal-containing solution and the NH4OH aqueous solution were continuously added to the reactor at a rate of 7.26 L / hr and 1.03 L / hr, respectively. At the same time, the NaOH aqueous solution was added via a pH sensor to gradually increase the pH, as shown in Figure 2(A), and a co-precipitation reaction was carried out for a total reaction time of 32 hours to grow positive electrode active material precursor particles. For reference, when the 100 L reactor was filled to capacity, the filtration system located within the reactor was activated, and the reacted solvent was continuously discharged outside the reactor while the transition metal-containing solution, NH4OH aqueous solution, and NaOH aqueous solution were continuously added.

[0191] The final composition of the positive electrode active material precursor particles was Ni 0.885 Co 0.035 Mn 0.08 (OH)2 and the average particle size (D 50 ) was 3.38 μm.

[0192] Example 2 MnSO4 and NiSO4 were added to distilled water in amounts such that the molar ratio of Mn:Ni was 65:35 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a 25 wt% NaOH aqueous solution and a 9 M NH4OH aqueous solution were prepared.

[0193] The vessel containing the transition metal-containing solution and the vessel containing the NaOH aqueous solution were each connected to a 100 L CFTR reactor 1 .

[0194] 40 L of deionized water, 50 mL of the NaOH aqueous solution, and 52 mL of the NH4OH aqueous solution were charged into the CFTR reactor 1, the pH was adjusted to 12, and nitrogen gas was purged into the reactor to remove dissolved oxygen in the water and create a non-oxidizing atmosphere inside the reactor.

[0195] Nitrogen and oxygen were then introduced into the CFTR reactor 1 at a volume ratio of 10:0.2 to form a weakly oxidizing atmosphere, and the transition metal-containing solution was continuously introduced into the reactor 1 at a rate of 4.16 L / hr. The NaOH aqueous solution was then introduced together with the transition metal-containing solution using a pH sensor, and a co-precipitation reaction was carried out for 20 hours to form a cathode active material precursor seed. The NaOH aqueous solution was introduced in an amount such that the pH gradually decreased from 12 to 10 for two hours after the introduction of the transition metal-containing solution, and then maintained at 10 for 18 hours.

[0196] Meanwhile, when the CFTR reactor 1 was filled with liquid, the filtration system located inside the reactor was activated, and the solvent in which the reaction was completed was continuously discharged to the outside of the reactor. At the same time, the transition metal-containing solution and the NaOH aqueous solution were continuously introduced to proceed with the coprecipitation reaction.

[0197] The average particle size (D 50 ) is 4.0 μm, and the average cross-sectional area of ​​the primary particles is 0.0194 μm 2 It was.

[0198] The vessel containing the transition metal-containing solution and the vessel containing the NaOH aqueous solution were each connected to a 100 L CFTR reactor 2.

[0199] Then, 3.2 kg of the prepared cathode active material precursor seeds, 45 L of deionized water, and 1.8 L of the NH4OH aqueous solution were added to the CFTR reactor 2, the pH was adjusted to 11.5 to 11.6, and nitrogen gas was purged into the reactor to remove dissolved oxygen in the water, creating a non-oxidizing atmosphere inside the reactor.

[0200] Nitrogen and oxygen were then introduced into the CFTR reactor 2 at a volume ratio of 10:0.2 to form a weakly oxidizing atmosphere, and the transition metal-containing solution was continuously introduced into the reactor 2 at a rate of 8.33 L / hr. The NaOH aqueous solution was then introduced together with the transition metal-containing solution using a pH sensor, and a co-precipitation reaction was carried out for 26 hours to grow cathode active material precursor particles. The NaOH aqueous solution was introduced in an amount such that the pH gradually decreased from pH 11.5-11.6 to pH 10 for 2 hours after the introduction of the transition metal-containing solution, and then maintained at pH 10 for 24 hours.

[0201] Meanwhile, when the CFTR reactor 2 was filled with the liquid, the filtration system located inside the reactor was activated, and the solvent in which the reaction was completed was continuously discharged to the outside of the reactor. At the same time, the transition metal-containing solution and the NaOH aqueous solution were continuously introduced to proceed with the co-precipitation reaction. The total composition of the finally produced cathode active material precursor particles was Mn 0.65 Ni 0.35 (OH)2 and the average particle size (D 50 ) was 10.00 μm.

[0202] Example 3 MnSO4 and NiSO4 were added to distilled water in amounts such that the molar ratio of Mn:Ni was 65:35 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a 25 wt% NaOH aqueous solution and a 9 M NH4OH aqueous solution were prepared.

[0203] The vessel containing the transition metal-containing solution and the vessel containing the NaOH aqueous solution were each connected to a 10 L CFTR reactor 1 .

[0204] 5 L of deionized water, 6.3 mL of the NaOH aqueous solution, and 6.4 mL of the NH4OH aqueous solution were added to the CFTR reactor, the pH was adjusted to 12, and nitrogen gas was purged into the reactor to remove dissolved oxygen in the water and create a non-oxidizing atmosphere inside the reactor.

[0205] Nitrogen and oxygen were then introduced into the CFTR reactor 1 in a volume ratio of 5:0.04 to form a weakly oxidizing atmosphere, and the transition metal-containing solution was continuously introduced into the reactor at a rate of 0.42 L / hr. The NaOH aqueous solution was then introduced together with the transition metal-containing solution using a pH sensor, and a co-precipitation reaction was carried out for 24 hours to form a cathode active material precursor seed. The NaOH aqueous solution was introduced in an amount such that the pH gradually decreased from 12 to 10 for two hours after the introduction of the transition metal-containing solution, and then maintained at 10 for 22 hours.

[0206] Meanwhile, when the CFTR reactor 1 was filled with liquid, the filtration system located inside the reactor was activated, and the solvent in which the reaction was completed was continuously discharged to the outside of the reactor. At the same time, the transition metal-containing solution and the NaOH aqueous solution were continuously introduced to proceed with the coprecipitation reaction.

[0207] During the reaction, the atmosphere in the CFTR reactor was adjusted to a nitrogen and oxygen ratio of 5:0.04 to 5:0.1 until the end of the reaction to obtain the desired primary particle shape.

[0208] The average particle size (D 50) is 4.0 μm, and the average cross-sectional area of ​​the primary particles is 0.0199 μm 2 It was.

[0209] The vessel containing the transition metal-containing solution and the vessel containing the NaOH aqueous solution were each connected to a 10 L CFTR reactor 2.

[0210] Then, 0.32 kg of the prepared cathode active material precursor seeds, 6 L of deionized water, and 1.45 mL of the NH4OH aqueous solution were added to the CFTR reactor 2, the pH was adjusted to 11.5 to 11.6, and nitrogen gas was purged into the reactor to remove dissolved oxygen in the water, creating a non-oxidizing atmosphere inside the reactor.

[0211] Nitrogen and oxygen were then introduced into the CFTR reactor 2 in a volume ratio of 5:0.04 to form a weakly oxidizing atmosphere, and the transition metal-containing solution was continuously introduced into the reactor at a rate of 0.83 L / hr. The NaOH aqueous solution was then introduced along with the transition metal-containing solution using a pH sensor, and a co-precipitation reaction was carried out for 20 hours to grow cathode active material precursor particles. The NaOH aqueous solution was introduced in an amount such that the pH gradually decreased from pH 11.5-11.6 to pH 10 for 2 hours after the introduction of the transition metal-containing solution, and then maintained at pH 10 for 18 hours.

[0212] Meanwhile, when the CFTR reactor 2 was filled with liquid, the filtration system located inside the reactor was activated, and the solvent in which the reaction was completed was continuously discharged to the outside of the reactor. At the same time, the transition metal-containing solution and the NaOH aqueous solution were continuously introduced to proceed with the coprecipitation reaction.

[0213] The final composition of the positive electrode active material precursor particles was Mn 0.65 Ni 0.35 (OH)2 and the average particle size (D 50 ) was 9.95 μm.

[0214] Comparative Example 1 NiSO4, CoSO4, and MnSO4 were added to distilled water in amounts such that the molar ratio of Ni:Co:Mn was 88.5:3.5:8.0 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a 7.96 M NaOH aqueous solution and a 5.08 M NH4OH aqueous solution were prepared.

[0215] As shown in FIG. 1, the vessel containing the transition metal-containing solution, the vessel containing the NaOH aqueous solution, and the vessel containing the NH 4 OH aqueous solution were each connected to a 100 L reactor.

[0216] After 28.59 L of deionized water, 0.035 L of the aqueous NaOH solution, and 0.216 L of the aqueous NH4OH solution were charged into the reactor, nitrogen gas was purged into the reactor to remove dissolved oxygen in the water and create a non-oxidizing atmosphere inside the reactor.

[0217] The transition metal-containing solution and the NH4OH aqueous solution were then continuously added to the reactor at a rate of 7.26 L / hr and 1.03 L / hr, respectively, while the NaOH aqueous solution was added via a pH sensor to control the pH as shown in Figure 2(B), allowing a co-precipitation reaction to occur for 1.5 hours to form cathode active material precursor seeds. Next, when the 100 L reactor was filled to capacity, the filtration system located within the reactor was activated, and the reacted solvent was continuously discharged to the outside of the reactor. The transition metal-containing solution, NH4OH aqueous solution, and NaOH aqueous solution were continuously added to the reactor for a total reaction time of 32 hours to grow cathode active material precursor particles.

[0218] Comparative Example 2 MnSO4 and NiSO4 were added to distilled water in amounts such that the molar ratio of Mn:Ni was 65:35 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a 25 wt% NaOH aqueous solution and a 9 M NH4OH aqueous solution were prepared.

[0219] The vessel containing the transition metal-containing solution and the vessel containing the NaOH aqueous solution were each connected to a 10 L CFTR reactor.

[0220] 3.6 L of deionized water and 325 mL of the NH4OH aqueous solution were added to the CFTR reactor, and the pH was adjusted to 11. Nitrogen gas was purged into the reactor to remove dissolved oxygen in the water, creating a non-oxidizing atmosphere inside the reactor.

[0221] Nitrogen gas was then introduced into the CFTR reactor to create an inert atmosphere, and the transition metal-containing solution was continuously introduced into the reactor at a rate of 0.82 L / hr. The NaOH aqueous solution was then introduced together with the transition metal-containing solution using a pH sensor, and a co-precipitation reaction was carried out for 43 hours to form a cathode active material precursor. The NaOH aqueous solution was introduced in an amount such that the pH gradually decreased from 11 to 10 for 2 hours after the introduction of the transition metal-containing solution, and then maintained at 10.5 for 41 hours.

[0222] Meanwhile, when the CFTR reactor was filled with liquid, the filtration system located inside the reactor was activated, and the solvent in which the reaction was completed was continuously discharged to the outside of the reactor. At the same time, the transition metal-containing solution and the NaOH aqueous solution were continuously introduced to proceed with the coprecipitation reaction.

[0223] The final composition of the positive electrode active material precursor particles was Mn 0.65 Ni 0.35 (OH)2 and the average particle size (D 50 ) was 11.9 μm.

[0224] Experimental Example 1 The positive electrode active material precursors produced in Examples 1 to 3 and Comparative Examples 1 and 2 were cut using an ion milling machine at a power of 6 KeV to obtain cross-sectional samples, and SEM images of the cross sections were obtained using a scanning electron microscope (SEM). Figure 3 shows SEM images of the cross sections of the positive electrode active material precursors produced in Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, Figure 3(A) shows SEM images of the cross sections of the positive electrode active material precursors produced in Example 1, Figure 3(B) shows SEM images of the cross sections of the positive electrode active material precursors produced in Example 2, Figure 3(C) shows SEM images of the cross sections of the positive electrode active material precursors produced in Example 3, Figure 3(D) shows SEM images of the cross sections of the positive electrode active material precursors produced in Comparative Example 1, and Figure 3(E) shows SEM images of the cross sections of the positive electrode active material precursors produced in Comparative Example 2.

[0225] The SEM images of the cross sections were analyzed using Image J to obtain the average cross-sectional area (A1) of the primary particles in the core portion and the average cross-sectional area (A2) of the primary particles in the shell portion of each of the positive electrode active material precursors prepared in the Examples and Comparative Examples, and the values ​​are shown in Table 1 below. The ratio (A2 / A1) of the average cross-sectional area of ​​the primary particles in the shell portion to the average cross-sectional area of ​​the primary particles in the core portion was then calculated and shown in Table 1 below.

[0226] In this case, the average cross-sectional area of ​​the primary particles is the average cross-sectional area of ​​one primary particle, and is the value obtained by dividing the total cross-sectional area of ​​several tens to several hundreds of primary particles by the number of primary particles.

[0227] [Table 1]

[0228] Experimental Example 2 Each of the positive electrode active material precursors produced in the examples and comparative examples was cut with an ion milling device at a power of 6 KeV to obtain a cross-sectional sample, and an SEM image of the cross section was obtained using a scanning electron microscope (SEM).

[0229] The SEM image of the cross section was analyzed using Image J, and the percentage (%) of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion, the percentage (%) of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion, and the percentage (%) of the cross-sectional area of ​​the core portion relative to the cross-sectional area of ​​the positive electrode active material precursor are shown in Table 2 below.

[0230] 4(A) to 4(C) are images obtained by analyzing FIG. 3(A) using Image J. FIG. 4(A) is an image for obtaining the percentage of the cross-sectional area of ​​all voids present in the positive electrode active material precursor relative to the total cross-sectional area of ​​the positive electrode active material precursor. FIG. 4(B) is an image for obtaining the percentage of the cross-sectional area of ​​the core portion relative to the cross-sectional area of ​​the positive electrode active material precursor. FIG. 4(C) is an image for obtaining the percentage of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion.

[0231] 5(A) to 5(C) are images obtained by analyzing FIG. 3(A) using Image J. FIG. 5(A) is an image for obtaining the percentage of the cross-sectional area of ​​all voids present in the positive electrode active material precursor relative to the total cross-sectional area of ​​the positive electrode active material precursor. FIG. 5(B) is an image for obtaining the percentage of the cross-sectional area of ​​the core portion relative to the cross-sectional area of ​​the positive electrode active material precursor. FIG. 5(C) is an image for obtaining the percentage of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion.

[0232] For reference, the percentage (%) of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion is the percentage (%) of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion from the percentage (%) of the cross-sectional area of ​​all voids present in the positive electrode active material precursor relative to the total cross-sectional area of ​​the positive electrode active material precursor.

[0233] [Table 2]

[0234] Experimental Example 3 1) Confirmation of the span value of the positive electrode active material precursor Using a particle size analyzer (S-3500, Microtrac), the D5 and D6 of the positive electrode active material precursors of Examples 1 to 3 and Comparative Examples 1 and 2 were measured. 50 , D 95 The span value of the positive electrode active material precursor was calculated using the following formula 4, and is shown in Table 3 below.

[0235] [Formula 4] Span = (D 95 -D5) / D 50

[0236] 2) Check the percentage of abnormal particles, particle aspect ratio, and circularity The proportion of abnormal particles, particle aspect ratio, and circularity can be measured from segmentation images divided into secondary particle units, which are obtained by image processing of scanning electron microscope (SEM) images using an artificial intelligence model. To illustrate this, (A) an SEM image and (B) a segmentation image obtained by image processing the SEM image are shown in FIG. 6. The segmentation image can be obtained by acquiring a scanning electron microscope (SEM) image of the cathode material powder to be measured, inputting the acquired SEM image into a U-NET structure to generate a binary image, converting the binary image into a distance transformed image using a distance transform algorithm, filtering the binary image using a threshold value set based on the distance transformed image, identifying multiple objects contained in the filtered binary image, and segmenting the SEM image into secondary particle units based on the multiple objects.

[0237] As shown by the dotted circle in the segmentation image in Figure 6(B), particles are recognized as abnormal when two or more particles are clustered together, rather than spherical secondary particles. The ratio of the number of abnormal particles to the total number of particles was confirmed and is shown in Table 3 below.

[0238] Then, in the segmentation image, the minor and major axes were set for each secondary particle unit as shown in the image in Figure 7, and the aspect ratio was calculated using the following equation 5, which is shown in Table 3. Figure 7 is a diagram showing the definition of the minor and major axes for calculating the aspect ratio of a particle.

[0239]

number

[0240] In addition, in the segmentation image, the circularity was calculated for each secondary particle unit using the following formula 6, and is shown in Table 3 below.

[0241] [Formula 6] Circularity = 4πA / P2

[0242] In Equation 6, A is the area of ​​each secondary particle measured in the segmentation image, and P is the perimeter of each secondary particle measured in the segmentation image.

[0243] For reference, the closer the aspect ratio and circularity are to 1.0, the better the sphericity.

[0244] [Table 3]

[0245] Referring to Table 3, it can be seen that the high-nickel NCM-based positive electrode active material precursor of Example 1 has a smaller span value and an aspect ratio and circularity closer to 1 than the high-nickel NCM-based positive electrode active material precursor of Comparative Example 1. It can also be seen that the Mn-rich NCM-based positive electrode active material precursors of Examples 2 and 3 not only have a smaller span value and fewer abnormal particles than the Mn-rich NCM-based positive electrode active material precursor of Comparative Example 2, but also have an aspect ratio and circularity closer to 1.

[0246] This confirms that the positive electrode active material precursor according to the present invention has a uniform particle size and excellent sphericity.

[0247] Experimental Example 4 The cathode active material precursors of Example 1 and Comparative Example 1 were mixed with LiOH so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the cathode active material precursor to the number of moles of lithium contained in LiOH was 1:0.98, and the mixture was primarily fired at 895°C for 6 hours to produce a primary fired product. The primarily fired product was mixed with LiOH so that the ratio of the total number of moles of transition metals (Ni+Co+Mn) contained in the cathode active material precursor to the number of moles of lithium contained in LiOH was 1:0.04, and the mixture was secondary fired at 820°C for 9 hours to produce a lithium composite transition metal oxide (cathode active material) in the form of a single particle having an average particle size of 4.8 μm.

[0248] FIG. 8(A) is an SEM image of a positive electrode active material produced using the positive electrode active material precursor of Example 1, and FIG. 8(B) is an SEM image of a positive electrode active material produced using the positive electrode active material precursor of Comparative Example 1.

[0249] The positive electrode active materials, conductive material (carbon black), and binder (PVdF) prepared as above were mixed in a weight ratio of 95:2:3 in N-methyl-2-pyrrolidone (NMP) solvent to prepare positive electrode slurry. The positive electrode slurry was applied to one side of an aluminum current collector, dried at 130°C, and rolled to prepare positive electrodes.

[0250] A separator was interposed between each of the positive and negative electrodes prepared as described above to prepare an electrode assembly, which was then placed inside a battery case. An electrolyte solution was then injected into the battery case to prepare a 2032-type coin cell-type lithium secondary battery.

[0251] In this case, a lithium metal disk was used as the negative electrode, and the electrolyte was prepared by dissolving 1M LiPF6 in an organic solvent made by mixing ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate in a volume ratio of 3:3:4.

[0252] Each lithium secondary battery prepared as described above was charged in CC / CV mode (CV 0.05C) at 25°C at a constant current of 0.2C up to 4.25V, and then discharged in CC mode at a constant current of 0.2C down to 2.5V to measure the initial charge capacity and discharge capacity. The measurement results are shown in Table 4 below.

[0253] Each lithium secondary battery fabricated as described above was subjected to CC / CV mode charging (CV 0.05C) at 45°C at a constant current of 0.1C to 4.4V, followed by CC mode discharging at a constant current of 0.1C to 2.5V. This cycle was repeated 50 times, with one cycle consisting of CC / CV mode charging (CV 0.05C) at a constant current of 0.5C to 4.4V, followed by CC mode discharging at a constant current of 1.0C to 2.5V. The resistance increase rate was calculated as the percentage of DICR (ΔV) calculated by dividing the voltage drop (ΔV) over 60 seconds in the 50th discharge cycle by the current, relative to DCIR (ΔV) calculated by dividing the voltage drop (ΔV) over 60 seconds in the first discharge cycle by the current, and is shown in Table 4 below.

[0254] [Table 4]

[0255] Referring to Table 4, it can be seen that the battery including the cathode active material produced using the cathode active material precursor of Example 1 has a higher capacity retention rate and a significantly lower resistance increase rate than the battery including the cathode active material produced using the cathode active material precursor of Comparative Example 1, in which the ratio of the average cross-sectional area of ​​the shell primary particles to the average cross-sectional area of ​​the core primary particles is small, at less than 3.00.

[0256] Therefore, it can be seen that the high-nickel NCM-based cathode active material precursor among the cathode active material precursors according to the present invention can easily form a cathode active material in a single-particle form with a high degree of single particle size when a mixture of the cathode active material precursor and a lithium-containing raw material is sintered, and lithium can easily diffuse to the core portion, thereby providing a cathode active material that can realize a battery with excellent capacity and resistance characteristics. [Explanation of symbols]

[0257] 100 reactor 200 Continuous Crusher

Claims

1. a core portion including first primary particles; a shell portion formed on the core portion and including second primary particles, a ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles in a cross section of the positive electrode active material precursor is 3.00 or more and 10.0 or less.

2. The average particle size (D ５０ 2. The positive electrode active material precursor according to claim 1, wherein the average particle diameter is 2.0 μm or more and 11.00 μm or less.

3. The positive electrode active material precursor according to claim 1 , wherein the core portion is in the form of a spherical secondary particle formed by agglomeration of the first primary particles.

4. The positive electrode active material precursor according to claim 1 , wherein the composite transition metal hydroxide has a composition represented by the following chemical formula 1: [Chemical formula 1] [Ni ａ１ Co ｂ１ M1 ｃ１ M2 ｄ１ ](O+) ２ (In the above chemical formula 1, M1 is one or more selected from Mn and Al; M2 is one or more selected from Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; 0.6≦a1<1, 0<b1≦0.4, 0<c1≦0.4, 0≦d1≦0.2.)

5. The positive electrode active material precursor according to claim 1 , wherein the composite transition metal hydroxide has a composition represented by the following chemical formula 2: [Chemical formula 2] [Mn ａ２ Ni ｂ２ Co ｃ２ M ｄ２ ](OH) ２ (In the above chemical formula 2, M is one or more selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; 0.5≦a2<1, 0<b2≦0.5, 0≦c2<0.5, 0≦d2≦0.2.)

6. In a cross section of the positive electrode active material precursor, a ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 4.60 or more and 5.00 or less, Average particle size (D ５０ 5. The positive electrode active material precursor according to claim 4, wherein the average particle size is 2.00 μm or more and 5.00 μm or less.

7. In a cross section of the positive electrode active material precursor, a ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particles to the average cross-sectional area (A1) of the first primary particles is 3.00 or more and 4.60 or less, Average particle size (D ５０ 6. The positive electrode active material precursor according to claim 5, wherein the average particle size is 9.50 μm or more and 11.00 μm or less.

8. The average cross-sectional area (A1) of the first primary particles is 0.0100 μm ２ ~0.0200μm ２ The positive electrode active material precursor according to claim 1 ,

9. The average cross-sectional area (A2) of the second primary particles is 0.0500 μm ２ ~0.1000μm ２ The positive electrode active material precursor according to claim 1 ,

10. 2. The positive electrode active material precursor according to claim 1, wherein in a cross section of the positive electrode active material precursor, a percentage of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion is 11.00% to 30.00%.

11. 2. The positive electrode active material precursor according to claim 1, wherein in a cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion is 2.00% to 7.00%.

12. 2. The cathode active material precursor according to claim 1, wherein, in a cross section of the cathode active material precursor, a difference (C-S) between a percentage (C) of the cross-sectional area of ​​all voids present in the core portion relative to the cross-sectional area of ​​the core portion and a percentage (S) of the cross-sectional area of ​​all voids present in the shell portion relative to the cross-sectional area of ​​the shell portion is 5.00% to 28.00%.

13. 2. The positive electrode active material precursor according to claim 1, wherein in a cross section of the positive electrode active material precursor, a percentage of a cross-sectional area of ​​the core portion relative to a cross-sectional area of ​​the positive electrode active material precursor is 5.00% to 50.00%.

14. A method for producing a positive electrode active material precursor using a reaction apparatus in which a reactor and a continuous grinder are connected, comprising: (S1) a step of repeatedly introducing a transition metal-containing solution, an ammonium ion-containing solution, and a basic aqueous solution into a reactor, forming a cathode active material precursor seed by a coprecipitation reaction while simultaneously operating a continuous pulverizer, discharging the cathode active material precursor seed from the reactor to the continuous pulverizer, and re-introducing the cathode active material precursor seed from the continuous pulverizer into the reactor; (S2) stopping the operation of the continuous mill and growing positive electrode active material precursor particles in the reactor, The step (S1) is carried out while gradually decreasing the pH, The method for producing a cathode active material precursor according to claim 1 , wherein the step (S2) is performed while gradually increasing the pH.

15. 15. The method for producing a positive electrode active material precursor according to claim 14, wherein the step (S1) is carried out while gradually decreasing the pH within a range of pH 12.6 to 11.

2.

16. The method for producing a positive electrode active material precursor according to claim 14, wherein the step (S2) is carried out while gradually increasing the pH within a range of pH 11.2 to 12.

6.

17. (S1') adding a transition metal-containing solution and a basic aqueous solution to a reactor and forming a positive electrode active material precursor seed by a coprecipitation reaction; (S2') adding a transition metal-containing solution and a basic aqueous solution to a reactor containing the cathode active material precursor seeds, and growing cathode active material precursor particles by a co-precipitation reaction; The step (S1') is carried out by gradually decreasing the pH from 12.0 or more to 9.0 to 11.0, and then maintaining the pH within the range of 9.0 to 11.0; 2. The method for producing a cathode active material precursor according to claim 1, wherein step (S2') is performed by gradually decreasing the pH from pH 11.5 to 11.7 to pH 9.0 to 11.0, and then maintaining the pH within the range of pH 9.0 to 11.

0.

18. The method for producing a positive electrode active material precursor according to claim 17 , wherein the step (S1′) is performed in an oxidizing atmosphere.

Images