Positive electrode active material precursor and preparation method thereof

Abstract

The present invention relates to a positive electrode active material precursor having a novel structure and a method for preparing the same, wherein a composite transition metal hydroxide contained in the positive electrode active material precursor contains: a core part containing first primary particles; and a shell portion formed on the core portion and including second primary particles, in which, in a cross-section of the positive electrode active material precursor, a ratio (A2 / A1) of an average cross-sectional area (A2) of the second primary particles to an average cross-sectional area (A1) of the first primary particles is in a range of 3.00 to 10.0.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority from Korean Patent Application No. 10-2023-0035835, filed on March 20, 2023, the disclosure of which is incorporated herein by reference. Technical Field

[0003] The invention relates to a positive electrode active material precursor with a novel structure and a preparation method thereof. Background Art

[0004] With the development of technology and the increase in demand for mobile devices, the demand for secondary batteries as energy sources has increased significantly. Among these secondary batteries, lithium secondary batteries with high energy density, high voltage, long cycle life and low self-discharge rate have been commercialized and widely used.

[0005] Lithium transition metal composite oxides have been used as positive electrode active materials for lithium secondary batteries. Among these oxides, lithium cobalt composite metal oxides, such as LiCoO2, have been primarily used due to their high operating voltage and excellent capacity characteristics. However, due to the unstable crystal structure caused by delithiation, LiCoO2 has very poor thermal properties. Furthermore, since LiCoO2 is expensive, there are limitations in using large amounts of LiCoO2 as a power source for applications such as electric vehicles.

[0006] Therefore, as a material to replace LiCoO2, lithium manganese-based metal oxides (LiMnO2 or LiMn2O4), lithium iron phosphate compounds (LiFePO4, etc.) or lithium nickel-based oxides (LiNiO2, etc.) have been developed. Among these materials, lithium nickel-based oxides, which can easily realize large-capacity batteries due to their high reversible capacity of about 200 mAh / g, have been more actively studied and developed. However, the limitations of LiNiO2 are that LiNiO2 has poorer thermal stability than LiCoO2, and when an internal short circuit occurs due to external pressure in a charged state, the positive electrode active material itself decomposes, resulting in battery rupture and fire. Therefore, as a method of improving the low thermal stability while maintaining the excellent reversible capacity of LiNiO2, NCM-based positive electrode active materials have been developed in which a portion of the nickel (Ni) is replaced by cobalt (Co), manganese (Mn) and / or aluminum (Al).

[0007] Recently, as the demand for secondary batteries with high energy density increases, high nickel (high Ni) NCM-based positive electrode active materials with high nickel content have been developed to increase the capacity of the positive electrode active materials. In addition, due to the recent rise in the price of Co, high manganese (Mn-rich) NCM-based positive electrode active materials that can meet high capacity while having a relatively low Co content have been developed.

[0008] For high-Ni NCM-based positive electrode active materials, although they have the advantage of achieving large capacity, due to the high nickel content, the amount of nickel oxidized in the same voltage range increases, and the amount of lithium ion movement increases. As a result, there is a problem of reduced structural stability of the positive electrode active material, thereby reducing long-term life and thermal stability. Therefore, it is necessary to develop a high-Ni NCM-based positive electrode active material with excellent physical properties (such as life characteristics and thermal stability) and high capacity characteristics. In particular, recently, in order to solve the structural and thermal stability problems of the positive electrode material itself in the form of secondary particles, the development of single-particle positive electrode materials has been accelerated. However, for positive electrode active materials in the form of small (small) single particles with small particle size, the cycle characteristics are excellent, but there is a problem of poor resistance characteristics. Therefore, it is necessary to develop a precursor that can realize a small single-particle positive electrode active material with excellent resistance characteristics and excellent cycle characteristics. In addition, in order to improve capacity and life, it is necessary to develop a high-density Mn-rich NCM-based positive electrode active material, and it is necessary to develop a precursor that can realize a high-density Mn-rich NCM-based positive electrode active material.

[0009] [Prior art literature]

[0010] [Patent Document]

[0011] Korean Patent Application Pending No. 10-2013-129449 Summary of the Invention

[0012] Technical issues

[0013] One aspect of the present invention provides a positive electrode active material precursor having a novel structure and a method for preparing the same that can achieve excellent lifespan and resistance characteristics.

[0014] Furthermore, another aspect of the present invention provides a positive electrode active material precursor having a novel structure in which particle size is uniform and sphericity is excellent, and a method for preparing the same.

[0015] Technical Solution

[0016] The present invention provides a positive electrode active material precursor and a preparation method thereof.

[0017] (1) The present invention provides a positive electrode active material precursor comprising a composite transition metal hydroxide, the composite transition metal hydroxide comprising: a core portion comprising a first primary particle; and a shell portion formed on the core portion and comprising a second primary particle, wherein, in a cross section of the positive electrode active material precursor, a ratio (A2 / A1) of an average cross-sectional area (A2) of the second primary particle to an average cross-sectional area (A1) of the first primary particle is in the range of 3.00 to 10.0.

[0018] (2) The present invention provides the precursor of the positive electrode active material of (1) above, wherein the average particle size (D

[0032] ) of the precursor of the positive electrode active material is 2.0 μm to 11.0 μm.

[0019] (3) The present invention provides the precursor of the positive electrode active material of (1) or (2) above, wherein the core part is in the form of spherical secondary particles formed by the aggregation of the first primary particles.

[0020] (4) The present invention provides the precursor of the positive electrode active material of any one of (1) to (3) above, wherein the composite transition metal hydroxide has the composition represented by Formula 1.

[0021] [Formula 1]

[0022] [Ni a1 Co b1 M1 c1 M2 d1 (OH)2

[0023] In Formula 1,

[0024] M1 is at least one selected from manganese (Mn) and aluminum (Al),

[0025] M2 is at least one selected from yttrium (Y), zirconium (Zr), boron (B), titanium (Ti), tungsten (W), niobium (Nb), strontium (Sr), molybdenum (Mo), magnesium (Mg), phosphorus (P), vanadium (V), tantalum (Ta), gallium (Ga) and calcium (Ca), and

[0026] 0.6 ≤ a1 < 1, 0 < b1 ≤ 0.4, 0 < c1 ≤ 0.4 and 0 ≤ d1 ≤ 0.2.

[0027] (5) The present invention provides the precursor of the positive electrode active material of any one of (1) to (3) above, wherein the composite transition metal hydroxide has the composition represented by Formula 2.

[0028] [Formula 2]

[0029] [Mn[[ID=​​​​​​​​​​​​​​​​

[0033] (6) The present invention provides the positive electrode active material precursor of (4) above, wherein, in the 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 in the range of 4.60 to 5.00, and the average particle size (D 50 ) is in the range of 2.00μm to 5.00μm.

[0034] (7) The present invention provides the positive electrode active material precursor of (5) above, wherein, in the 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 in the range of 3.00 to 4.60, and the average particle size (D 50 ) is in the range of 9.50μm to 11.00μm.

[0035] (8) The present invention provides a positive electrode active material precursor according to any one of (1) to (7) above, wherein the average cross-sectional area (A1) of the first primary particle is 0.0100 μm 2 to 0.0200μm 2 within the range.

[0036] (9) The present invention provides a positive electrode active material precursor according to any one of (1) to (8) above, wherein the average cross-sectional area (A2) of the second primary particles is 0.0500 μm 2 to 0.1000μm 2 within the range.

[0037] (10) The present invention provides a positive electrode active material precursor of any one of (1) to (9) above, wherein, in the cross-section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all pores present in the core portion in the cross-sectional area of ​​the core portion is in the range of 11.00% to 30.00%.

[0038] (11) The present invention provides a positive electrode active material precursor of any one of (1) to (10) above, wherein, in the cross-section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​all pores present in the shell portion in the cross-sectional area of ​​the shell portion is in the range of 2.00% to 7.00%.

[0039] (12) The present invention provides a positive electrode active material precursor of any one of (1) to (11) above, wherein, in the cross-section of the positive electrode active material precursor, the difference (CS) between the percentage (C) of the cross-sectional area of ​​all pores present in the core portion in the cross-sectional area of ​​the core portion and the percentage (S) of the cross-sectional area of ​​all pores present in the shell portion in the cross-sectional area of ​​the shell portion is in the range of 5.00% to 28.00%.

[0040] (13) The present invention provides a positive electrode active material precursor of any one of (1) to (12) above, wherein, in the cross-section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​the core portion in the cross-sectional area of ​​the positive electrode active material precursor is in the range of 5.00% to 50.00%.

[0041] (14) The present invention provides a method for preparing a positive electrode active material precursor of any one of the above (1) to (9) using a reaction apparatus connected to a reactor and a continuous grinder, the method comprising the following steps: (S1) introducing a transition metal-containing solution, an ammonium ion-containing solution and an alkaline aqueous solution into a reactor, forming positive electrode active material precursor seed crystals through a co-precipitation reaction, while operating the continuous grinder, repeating the process of discharging the positive electrode active material precursor seed crystals from the reactor into the continuous grinder and reintroducing the positive electrode active material precursor seed crystals from the continuous grinder into the reactor; and (S2) stopping the operation of the continuous grinder and growing positive electrode active material precursor particles in the reactor, wherein step (S1) is carried out while gradually lowering the pH, and step (S2) is carried out while gradually raising the pH.

[0042] (15) The present invention provides the method of (14) above, wherein step (S1) is performed while gradually lowering the pH within the range of 12.6 to 11.2.

[0043] (16) The present invention provides the method of (14) or (15) above, wherein step (S2) is performed while gradually increasing the pH within the range of 11.2 to 12.6.

[0044] (17) The present invention provides a method for preparing a positive electrode active material precursor of any one of the above (1) to (9), the method comprising the following steps: (S1') introducing a transition metal-containing solution and an alkaline aqueous solution into a reactor to form positive electrode active material precursor seed crystals by a co-precipitation reaction; and (S2') introducing a transition metal-containing solution and an alkaline aqueous solution into a reactor containing positive electrode active material precursor seed crystals to grow positive electrode active material precursor particles by a co-precipitation reaction, wherein step (S1') is carried out while maintaining the pH in the range of 9.0 to 11.0 after gradually reducing the pH from above 12.0 to the range of 9.0 to 11.0, and step (S2') is carried out while maintaining the pH in the range of 9.0 to 11.0 after gradually reducing the pH from the range of 11.5 to 11.7 to the range of 9.0 to 11.0.

[0045] (18) The present invention provides the method of (17) above, wherein step (S1') is performed in an oxidizing atmosphere.

[0046] Beneficial effects

[0047] Since the composite transition metal hydroxide contained in the positive electrode active material precursor of the present invention contains: a core portion containing a first primary particle; and a shell portion formed on the core portion and containing a second primary particle, and the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particle to the average cross-sectional area (A1) of the first primary particle satisfies the range of 3.00 to 10.0, a high-density positive electrode active material precursor with uniform particle size and excellent sphericity can be provided.

[0048] Moreover, when the positive electrode active material precursor is a high-Ni NCM-based positive electrode active material, when the mixture of the positive electrode active material precursor and the lithium-containing raw material is sintered, the positive electrode active material in the form of single particles with a high degree of single particle formation can be easily formed, and lithium can be easily diffused into the core portion to realize a low-resistance positive electrode active material. Therefore, the capacity characteristics and life characteristics of the battery using the positive electrode active material prepared from the positive electrode active material precursor of the present invention can be improved.

[0049] The method for preparing a cathode active material according to an embodiment of the present invention can improve the formation efficiency of a cathode active material precursor and easily provide the cathode active material precursor of the present invention by using a reaction apparatus connected to a reactor and a continuous grinder and appropriately adjusting pH.

[0050] The method for preparing a positive electrode active material according to another embodiment of the present invention can easily provide a positive electrode active material precursor of the present invention by appropriately adjusting pH and introducing or not introducing a solution containing ammonium ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Schematically shows a reaction apparatus that can be used in the method for preparing a positive electrode active material precursor of the present invention.

[0052] Figure 2 (A) is a graph showing the pH according to the preparation time of the positive electrode active material precursor of Example 1, Figure 2 (B) is a graph showing pH according to preparation time of the positive electrode active material precursor of Comparative Example 1.

[0053] Figure 3 are cross-sectional scanning electron microscope (SEM) images of the positive electrode active material precursors prepared in (A) Example 1, (B) Example 2, (C) Example 3, (D) Comparative Example 1, and (E) Comparative Example 2.

[0054] Figure 4 (A) to 4(C) were analyzed by using Image J Figure 3 (A) The image obtained.

[0055] Figure 5 (A) to 5(C) were analyzed by using Image J Figure 3 (D) The image obtained.

[0056] Figure 6 (A) A SEM image according to an embodiment of the present invention and (B) a segmented image obtained by image processing the SEM image are shown.

[0057] Figure 7 : is a diagram showing the definition of the minor axis and the major axis used to calculate the aspect ratio of a particle.

[0058] Figure 8 (A) A SEM image of a positive electrode active material prepared using the positive electrode active material precursor of Example 1, and (B) a SEM image of a positive electrode active material prepared using the positive electrode active material precursor of Comparative Example 1 are shown. DETAILED DESCRIPTION

[0059] Hereinafter, the present invention will be described in more detail to allow a clearer understanding of the present invention.

[0060] It will be understood that the words or terms used in the specification and claims should not be interpreted as the meanings defined in commonly used dictionaries, and it will be further understood that, based on the principle that the inventor can appropriately define the meanings of words or terms to best interpret the present invention, the words or terms should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology and the technical concept of the present invention.

[0061] It will be further understood that the terms “comprises,” “comprising,” or “having” in this specification specify the presence of stated features, numbers, steps, elements, or combinations thereof, but do not preclude the presence or addition of one or more other features, numbers, steps, elements, or combinations thereof.

[0062] The term "on" in this specification not only means a case where one component is directly formed on an upper surface of another component, but also includes a case where an intermediate component may also exist.

[0063] In this specification, the term "single-particle positive electrode active material" refers to a concept that contrasts with a spherical secondary particle positive electrode active material prepared by conventional methods, which is formed by the aggregation of tens to hundreds of primary particles. Specifically, in the present invention, a single-particle positive electrode active material may be a single particle consisting of one primary particle or a secondary particle composed of several primary particles.

[0064] The “primary particle” refers to the smallest unit of a particle recognized when the positive electrode active material is observed through a scanning electron microscope, and the “secondary particle” refers to a secondary structure formed by aggregation of a plurality of primary particles.

[0065] In this specification, the “average cross-sectional area of ​​primary particles” is a value obtained by dividing the total cross-sectional area of ​​tens to hundreds of primary particles present in the cross section of the positive electrode active material precursor by the number of primary particles.

[0066] In this specification, the expression "average particle size (D 50 )” represents the particle size at 50% of the cumulative volume distribution of the particle size. After dispersing the measurement target powder in a dispersion medium, the dispersion medium is introduced into a commercial laser diffraction particle size measuring instrument (e.g., Microtrac S3500), and the particle size distribution is calculated by measuring the difference in the diffraction pattern due to the particle size when the particles pass through the laser beam, and by using the measuring instrument to calculate the particle size at 50% of the cumulative volume distribution of the particle size, D can be measured. 50 .

[0067] In this specification, the “cross-sectional area of ​​the positive electrode active material precursor” refers to 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” refers to 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” refers to 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.

[0068] Positive electrode active material precursor

[0069] The present invention provides a positive electrode active material precursor, comprising: a core portion comprising first primary particles; and a shell portion formed on the core portion and comprising second primary particles, wherein, in a cross section of the positive electrode active material precursor, a ratio (A2 / A1) of an average cross-sectional area (A2) of the second primary particles to an average cross-sectional area (A1) of the first primary particles is in the range of 3.00 to 10.0.

[0070] As the primary particle size of the shell portion of a positive electrode active material precursor increases, it becomes more difficult for lithium to diffuse into the core portion when a mixture of the precursor and a lithium-containing raw material is sintered, resulting in defects in the core portion. Therefore, the inventors of the present invention attempted to improve the performance of the positive electrode active material by minimizing the thick shell portion of the primary particle and achieving a core portion where lithium can easily diffuse.

[0071] The positive electrode active material precursor of 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 satisfies the range of 3.00 to 10.0. In this case, there are the following advantages: the positive electrode active material precursor has a uniform particle size, excellent sphericity and high density. Moreover, when the mixture of the positive electrode active material precursor and the lithium-containing raw material is sintered, lithium can be easily diffused to the core portion to achieve a low-resistance positive electrode active material. The (A2 / A1) value can specifically 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, and can be 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.

[0072] When the (A2 / A1) value is less than 3.00, defects may occur in the core portion because lithium does not readily diffuse into the core portion when the mixture of the precursor and the lithium-containing raw material is sintered. Furthermore, when the (A2 / A1) value is greater than 10.0, electrolyte addition may be difficult, and a significant difference may appear between the internal and external structures of the positive electrode active material after sintering.

[0073] The average particle size (D 50 ) may be 2.0 μm to 11.00 μm. When the average particle size of the positive electrode active material precursor is within the above range, high-density positive electrode active materials of various sizes may be realized.

[0074] According to the present invention, the core part may be in the form of spherical secondary particles formed by aggregation of primary particles for the first time. That is, the precursor of the positive electrode active material of the present invention may have an overall spherical shape due to the aggregation of primary particles for the second time on the core part (which is in the form of spherical secondary particles formed by aggregation of primary particles for the first time).

[0075] According to the present invention, the composite transition metal hydroxide may have a composition represented by the following Formula 1 or Formula 2.

[0076] [Formula 1]

[0077] [Ni a1 Co b1 M1 c1 M2 d1 (OH)2

[0078] In Formula 1,

[0079] M1 is at least one selected from manganese (Mn) and aluminum (Al),

[0080] M2 is at least one selected from yttrium (Y), zirconium (Zr), boron (B), titanium (Ti), tungsten (W), niobium (Nb), strontium (Sr), molybdenum (Mo), magnesium (Mg), phosphorus (P), vanadium (V), tantalum (Ta), gallium (Ga), and calcium (Ca), and

[0081] 0.6 ≤ a1 < 1, 0 < b1 ≤ 0.4, 0 < c1 ≤ 0.4 and 0 ≤ d1 ≤ 0.2. [[ID=​​​​​​​​​​​​​

[0087] [Mn a2 Ni b2 Co c2 M d2 (OH)2

[0088] In Formula 2,

[0089] M is at least one selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca, and

[0090] 0.5 ≤ a2 < 1, 0 < b2 ≤ 0.5, 0 ≤ c2 < 0.5, and 0 ≤ d2 ≤ 0.2.

[0091] a2 represents the atomic fraction of manganese among the metal elements in the composite transition metal hydroxide having the composition represented by Formula 2, where a2 can satisfy 0.5 ≤ a2 < 1, 0.6 ≤ a2 ≤ 0.95, or 0.65 ≤ a2 ≤ 0.9.

[0092] b2 represents the atomic fraction of nickel among the metal elements in the composite transition metal hydroxide having the composition represented by Formula 2, where b2 can satisfy 0 < b2 ≤ 0.5, 0.05 ≤ b2 ≤ 0.4, or 0.1 ≤ b2 ≤ 0.35.

[0093] c2 represents the atomic fraction of cobalt among the metal elements in the composite transition metal hydroxide having the composition represented by Formula 2, where c2 can satisfy 0 ≤ c2 < 0.5, 0 ≤ c2 ≤ 0.2, or 0 ≤ c2 ≤ 0.15.

[0094] d2 represents the atomic fraction of element M among the metal elements in the composite transition metal hydroxide having the composition represented by Formula 2, where d2 can satisfy 0 ≤ d2 ≤ 0.2, 0 ≤ d2 ≤ 0.1, or 0 ≤ d2 ≤ 0.05.

[0095] According to the present invention, when the composite transition metal hydroxide has the composition represented by Formula 1, in the cross-section of the precursor of the positive electrode active material, 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 can be in the range of 4.60 to 5.00, and the average particle size (D 50 ) can be in the range of 2.00 μm to 5.00 μm. In this case, when sintering a mixture of the precursor of the positive electrode active material and a lithium-containing raw material, a positive electrode active material in the form of single particles with a high degree of single particle formation can be easily formed, and since lithium can easily diffuse to the core part, a positive electrode active material with low resistance can be achieved. In addition, the span (=(D 95 - D5) / D 50 ) value can be 1.0 or less.

[0096] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the (A2 / A1) value may be specifically 4.60 or more, and may be 4.70 or less, 4.80 or less, 4.90 or less, or 5.00 or less. 50 ) can be above 2.00 μm, above 2.10 μm, above 2.20 μm, above 2.30 μm, above 2.40 μm, above 2.50 μm, above 2.60 μm, above 2.70 μm, above 2.80 μm, above 2.90 μm, above 3.00 μm, above 3.10 μm, above 3.20 μm, or above 3.30 μm, and can be below 3.50 μm, below 3.60 μm, below 3.70 μm, below 3.80 μm, below 3.90 μm, below 4.00 μm, below 4.50 μm, or below 5.00 μm.

[0097] According to the present invention, in the case where the composite transition metal hydroxide has a composition represented by Formula 2, in the cross section of the positive electrode active material precursor, the ratio (A2 / A1) of the average cross-sectional area (A2) of the second primary particle to the average cross-sectional area (A1) of the first primary particle may be in the range of 3.00 to 4.60, and the average particle size (D 50 ) can be in the range of 9.50 μm to 11.00 μm. In this case, even if the positive active material precursor is a large particle, it can have a uniform particle size, excellent sphericity and high density. Regarding the particle size uniformity, the span (=(D 95 -D5) / D 50 ) value can be below 0.65.

[0098] When the composite transition metal hydroxide has a composition represented by Formula 2, the (A2 / A1) value 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) can be greater than 9.50 μm, greater than 9.60 μm, greater than 9.70 μm, greater than 9.80 μm, greater than 9.90 μm, or greater than 9.95 μm, and can be less than 10.00 μm, less than 10.10 μm, less than 10.20 μm, less than 10.30 μm, less than 10.40 μm, less than 10.50 μm, less than 10.60 μm, less than 10.70 μm, less than 10.80 μm, less than 10.90 μm, or less than 11.00 μm.

[0099] According to the present invention, the average cross-sectional area (A1) of the first primary particles can be 0.0100 μm 2 to 0.0200μm 2 In this case, when the mixture of the precursor and the lithium-containing raw material is sintered, lithium can be easily diffused into the core portion, and as a result, since a positive electrode active material without defects can be formed, the performance of the positive electrode active material can be improved. The average cross-sectional area of ​​the first primary particle can specifically be 0.0100 μm 2 Above, 0.0110μm 2 Above, 0.0120μm 2 Above, 0.0130μm 2 Above, or 0.0140μm 2 above, and can be 0.0199μm 2 , or 0.0200μm 2 the following.

[0100] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the A1 value may be specifically 0.0100 μm 2 Above, 0.0110μm 2 Above, 0.0120μm 2 Above, 0.0130μm 2 Above, or 0.0140μm 2 above, and can be 0.0150μm 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 Below, or 0.0200μm 2 the following.

[0101] In the case where the composite transition metal hydroxide has a composition represented by Formula 2, the A1 value may be specifically 0.0100 μm 2 Above, 0.0110μm 2 Above, 0.0120μm 2 Above, 0.0130μm 2 Above, 0.0140μm 2 Above, 0.0150μm 2 Above, 0.0160μm 2 Above, 0.0170μm 2 Above, 0.0180μm 2 Above, or 0.0190μm 2 above, and can be 0.0199μm 2 Below, or 0.0200μm 2 the following.

[0102] According to the present invention, the average cross-sectional area (A2) of the second primary particles can be 0.0500 μm 2 to 0.1000μm 2 In this case, when the mixture of the precursor and the lithium-containing raw material is sintered, a single-particle positive electrode active material or a secondary-particle positive electrode active material with a high density can be easily formed. The average cross-sectional area of ​​the second primary particle can be specifically 0.0500 μm 2 Above, 0.0550μm 2 Above, 0.0600μm 2 Above, or 0.0650μm 2 above, and can be 0.0900μm 2 Below, 0.0950μm 2 Below, or 0.1000μm 2 the following.

[0103] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the A2 value may be specifically 0.0500 μm 2 Above, 0.0550μm 2 Above, 0.0600μm 2 Above, or 0.0650μm 2 above, and can be 0.0700μm 2 Below, 0.0750μm 2 Below, 0.0800μm 2 Below, 0.0850μm 2 Below, 0.0900μm 2 Below, 0.0950μm 2Below, or 0.1000μm 2 the following.

[0104] In the case where the composite transition metal hydroxide has a composition represented by Formula 2, the A2 value may be specifically 0.0500 μm 2 Above, 0.0550μm 2 Above, 0.0600μm 2 Above, or 0.0650μm 2 Above, 0.0700μm 2 Above, 0.0750μm 2 Above, 0.0800μm 2 Above, 0.0810μm 2 Above, 0.0820μm 2 Above, 0.0830μm 2 Above, or 0.0840μm 2 above, and can be 0.0900μm 2 Below, 0.0950μm 2 Below, or 0.1000μm 2 the following.

[0105] 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 pores present in the core portion in the cross-sectional area of ​​the core portion can be in the range of 11.00% to 30.00%. That is, in the cross-section of the positive electrode active material precursor, the value according to the following equation 1 can be in the range of 12.00% to 30.00%. In this case, when the precursor is used to prepare the positive electrode active material, a single particle form of a positive electrode active material with no defects in the core portion or a secondary particle form of a positive electrode active material with a high density can be prepared. The value according to equation 1 can specifically 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, and can 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.

[0106] [Equation 1]

[0107]

[0108] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the value according to Formula 1 can specifically be 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 can 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.

[0109] In the case where the composite transition metal hydroxide has a composition represented by Formula 2, the value according to Formula 1 can specifically 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, and can 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.

[0110] 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 pores present in the shell portion in the cross-sectional area of ​​the shell portion can be in the range of 2.00% to 7.00%. That is, in the cross-section of the positive electrode active material precursor, the value according to the following equation 2 can be in the range of 2.00% to 5.00%. In this case, when the precursor is used to prepare the positive electrode active material, a high-density positive electrode active material can be prepared even at a low sintering temperature. The value according to equation 2 can specifically 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, and can 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.

[0111] [Equation 2]

[0112]

[0113] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the value according to Formula 2 may specifically 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, 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. , less than 5.20%, less than 5.30%, less than 5.40%, less than 5.50%, less than 5.60%, less than 5.70%, less than 5.80%, less than 5.90%, less than 6.00%, less than 6.10%, less than 6.20%, less than 6.30%, less than 6.40%, less than 6.50%, less than 6.60%, less than 6.70%, less than 6.80%, less than 6.90%, or less than 7.00%.

[0114] In the case where the composite transition metal hydroxide has a composition represented by Formula 2, the value according to Formula 2 can specifically 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, 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, 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 can 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.

[0115] According to the present invention, in the cross section of the positive electrode active material precursor, the difference (CS) between the percentage (C) of the cross-sectional area of ​​all pores present in the core portion to the cross-sectional area of ​​the core portion and the percentage (S) of the cross-sectional area of ​​all pores present in the shell portion to the cross-sectional area of ​​the shell portion can be in the range of 5.00% to 28.00%. In this case, when the mixture of the positive electrode active material precursor and the lithium-containing raw material is sintered, a positive electrode active material in the form of single particles with a high degree of single particle formation or a positive electrode active material in the form of secondary particles with a high density can be easily formed, and since lithium can easily diffuse into the core portion, a low-resistance positive electrode active material can be realized. The (CS) value may specifically 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.

[0116] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the (CS) value may specifically be 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.

[0117] In the case where the composite transition metal hydroxide has a composition represented by Formula 2, the (CS) value may specifically 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.

[0118] According to the present invention, in the cross section of the positive electrode active material precursor, the percentage of the cross-sectional area of ​​the core portion in the cross-sectional area of ​​the positive electrode active material precursor can be in the range of 5.00% to 50.00%. That is, in the cross section of the positive electrode active material precursor, the value according to the following equation 3 can be in the range of 5.00% to 50.00%. In this case, when the mixture of the positive electrode active material precursor and the lithium-containing raw material is sintered, a positive electrode active material in the form of a single particle with a high single particle formation degree or a positive electrode active material in the form of a secondary particle with a high density can be easily formed. The value according to equation 3 can specifically 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, and can be 32.00% or less, 35.00% or less, 40.00% or less, 45.00% or less, or 50.00% or less.

[0119] [Equation 3]

[0120]

[0121] In the case where the composite transition metal hydroxide has a composition represented by Formula 1, the value according to Equation 3 can specifically be 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 can be 32.00% or less, 35.00% or less, 40.00% or less, 45.00% or less, or 50.00% or less.

[0122] In the case where the composite transition metal hydroxide has a composition represented by Formula 2, the value according to Formula 3 can specifically 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, and can 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.

[0123] Preparation method of positive electrode active material precursor (1)

[0124] Furthermore, the present invention provides a method (1) for preparing a positive electrode active material precursor.

[0125] The preparation method (1) of the positive electrode active material precursor of the present invention is a method for preparing a positive electrode active material precursor using a reaction device connected to a reactor and a continuous grinder, wherein the method comprises the following steps: (S1) introducing a transition metal-containing solution, an ammonium ion-containing solution, and an alkaline aqueous solution into a reactor to form positive electrode active material precursor seeds by a coprecipitation reaction, while operating the continuous grinder, repeating the process of discharging the positive electrode active material precursor seeds from the reactor into the continuous grinder and reintroducing the positive electrode active material precursor seeds from the continuous grinder into the reactor; and (S2) stopping the operation of the continuous grinder and growing positive electrode active material precursor particles in the reactor, wherein step (S1) is performed while gradually lowering the pH, and step (S2) can be performed while gradually raising the pH. As described above, the preparation method of the positive electrode active material precursor of the present invention can improve the formation efficiency of the positive electrode active material precursor by using a reaction device connected to a reactor and a continuous grinder and appropriately adjusting the pH, and can also easily provide the positive electrode active material precursor of the present invention.

[0126] The method (1) for preparing a positive electrode active material precursor is a method suitable for preparing a positive electrode active material precursor containing a composite transition metal hydroxide having a composition represented by Formula 1.

[0127] Step (S1)

[0128] Step (S1) is a step of introducing a transition metal-containing solution, an ammonium ion-containing solution and an alkaline aqueous solution into a reactor, forming positive electrode active material precursor crystal seeds through a coprecipitation reaction, and simultaneously running a continuous grinder, repeatedly discharging the positive electrode active material precursor crystal seeds from the reactor into the continuous grinder and reintroducing the positive electrode active material precursor crystal seeds from the continuous grinder into the reactor.

[0129] Figure 1 1 is a diagram schematically showing a reaction apparatus that can be used in the method for preparing a positive electrode active material precursor of the present invention. The preparation method of the present invention uses a reaction apparatus having a reactor 100 and a continuous grinder 200 connected thereto.

[0130] In step ( S1 ), a solution containing a transition metal, a solution containing ammonium ions, and an alkaline aqueous solution are introduced into the reactor 100 , and positive electrode active material precursor seed crystals are formed in the reactor 100 .

[0131] The reactor 100 may be used regardless of the type of reactor, such as a batch reactor, a continuous stirred tank reactor (CSTR), or a continuous filter tank reactor (CFTR), among others.

[0132] More specifically, a reactor equipped with a filtration device inside the reactor, such as a continuous filter tank reactor (CFTR), can be used. In this case, a solution containing a transition metal, a solution containing ammonium ions, and an alkaline aqueous solution can be continuously introduced.

[0133] While initiating a coprecipitation reaction by introducing a transition metal-containing solution, an ammonium ion-containing solution, and an alkaline aqueous solution, seed cores of positive electrode active material precursor particles in the form of primary particles are formed, wherein the positive electrode active material precursor seed crystals formed in step (S1) may refer to seeds formed by aggregation of seed cores in the form of primary particles. If the positive electrode active material precursor seed crystals pass through a continuous grinder as described later and are then reintroduced into the reactor, the positive electrode active material precursor seed crystals aggregate (through a particle growth process) to form cores of the positive electrode active material precursor.

[0134] The solution containing a transition metal may contain cations of at least one metal selected from nickel (Ni), manganese (Mn), cobalt (Co), tungsten (W), molybdenum (Mo), chromium (Cr), and aluminum (Al). The solution containing metal ions may include acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, or oxyhydroxides of the above metals, and is not particularly limited as long as it is soluble in water.

[0135] For example, cobalt (Co) may be contained as Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, CoSO4, or Co(SO4)2·7H2O, and any one of them or a mixture of two or more thereof may be used. In addition, nickel (Ni) may be contained as Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, a fatty acid nickel salt, or a nickel halide, and any one of them or a mixture of two or more thereof may be used. Moreover, manganese (Mn) may be included as manganese oxides such as Mn2O3, MnO2, and Mn3O4; manganese salts such as MnCO3, Mn(NO3)2, MnSO4, manganese acetate, manganese dicarboxylate, manganese citrate, and fatty acid manganese salts; manganese oxyhydroxide or manganese chloride, and any one of them or a mixture of two or more thereof may be used.

[0136] 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) (for example, M is at least one element selected from zirconium (Zr), titanium (Ti), magnesium (Mg), tantalum (Ta), and niobium (Nb)), a raw material containing the second metal element may be optionally added when preparing the transition metal-containing solution. The raw material containing the second metal element may include an acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide containing the second metal element, and any one of these or a mixture of two or more thereof may be used. For example, when the second metal element is Zr, zirconium oxide or the like may be used.

[0137] The ammonium ion-containing solution may include at least one selected from NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3. As the solvent, water or a mixture of water and an organic solvent uniformly miscible with water (specifically, alcohol, etc.) may be used.

[0138] The alkaline aqueous solution may include at least one selected from hydrates of alkali metals, hydroxides of alkali metals, hydrates of alkaline earth metals, and hydroxides of alkaline earth metals. For example, the alkaline aqueous solution may include NaOH, KOH, or Ca(OH) 2, and as the solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) uniformly miscible with water may be used.

[0139] According to the present invention, step (S1) can be carried out while gradually reducing the pH within the range of 12.6 to 11.2. In this case, it may be beneficial to form seed crystals. The pH can be adjusted with an alkaline aqueous solution.

[0140] Since step (S1) includes forming positive electrode active material precursor crystals, operating a continuous grinder at the same time, and repeating the process of discharging the positive electrode active material precursor crystals from the reactor into the continuous grinder and reintroducing the positive electrode active material precursor crystals from the continuous grinder into the reactor, it can inhibit the growth of particles caused by the enrichment of the positive electrode active material precursor crystals in the reactor.

[0141] The positive electrode active material precursor seed crystals formed in step (S1) are not enriched in the reactor, but are ground in a continuous grinder and then reintroduced into the reactor.

[0142] If the reaction continues after the reaction solution is added to the reactor, particle aggregation occurs, and this often occurs severely, especially until the reaction progress rate in the reactor reaches 30%. In the present invention, before the reaction in the reactor progresses significantly and causes particle aggregation, the positive electrode active material precursor seed crystals are introduced into a continuous mill to be divided into small sizes, thereby suppressing aggregation and uniformly controlling the particle size.

[0143] Therefore, the positive electrode active material precursor seed crystals reintroduced into the reactor by the above method in the present invention have a narrow and uniform particle size distribution. Therefore, due to the small particle size and large contact area of ​​the seed crystals, not only is the formation efficiency of the positive electrode active material precursor improved, but also a positive electrode active material precursor with a uniform particle size can be provided as a result.

[0144] The rate at which the positive electrode active material precursor seed crystals are discharged from the reactor into the continuous grinder and the rate at which the positive electrode active material precursor seed crystals are reintroduced from the continuous grinder into the reactor may each independently be [reactor 100 capacity (L) × 6] / [hr] or more, and specifically may be [reactor 100 capacity (L) × 8] / [hr] or more, [reactor 100 capacity (L) × 10] / [hr] or more, or [reactor 100 capacity (L) × 12] / [hr] or more. In this case, the effect of grinding the seed crystals into a small size and uniformly controlling the particle size can be fully achieved.

[0145] The method for preparing the positive electrode active material precursor of the present invention may further include step (S1) between step (S1) and step (S2). + ), which grows positive electrode active material precursor particles by adding a reaction solution containing a transition metal-containing solution, an ammonium ion-containing solution, and an alkaline aqueous solution to a reactor, and simultaneously repeatedly discharges the positive electrode active material precursor particles from the reactor into the continuous grinder and reintroduces the positive electrode active material precursor particles from the continuous grinder into the reactor by running a continuous grinder. In this case, step (S1 + ) can be carried out while gradually increasing the pH.

[0146] In step (S1 + ), the description of the transition metal-containing solution, the ammonium ion-containing solution, the alkaline aqueous solution and the continuous grinding mill is the same as that in step (S1). That is, step (S1) and step (S1 + ) may differ only in pH conditions.

[0147] Step (S1 +) can be performed while gradually increasing the pH within the range of 11.2 to 12.6. In this case, thin primary particles can be formed at a pH of 11.2 to 11.8, and thick primary particles can be formed at a pH of 11.8 to 12.6. The pH can be adjusted with an alkaline aqueous solution.

[0148] Step (S2)

[0149] Step (S2) is a step of stopping the operation of the continuous grinder and growing positive electrode active material precursor particles in the reactor.

[0150] This is a step of preparing a positive electrode active material precursor using positive electrode active material precursor seed crystals having a uniform particle size that have been obtained in the reactor through step (S1), wherein, in order to prevent the positive electrode active material precursor seed crystals from being continuously discharged into the continuous grinder and being ground, the operation of the continuous grinder is stopped after step (S1) is fully performed, and positive electrode active material precursor particles are grown while adding a reaction solution containing a transition metal-containing solution, an ammonium ion-containing solution and an alkaline aqueous solution to the reactor.

[0151] According to the present invention, step (S2) can be performed while gradually increasing the pH in the range of 11.2 to 12.6. In this case, since thin primary particles are formed at a pH of 11.2 to 11.8 and thick primary particles are formed at a pH of 11.8 to 12.6, the positive electrode active material precursor of the present invention can be prepared. The pH can be adjusted with an alkaline aqueous solution.

[0152] Preparation method of positive electrode active material precursor (2)

[0153] In addition, the present invention provides a method for preparing a positive electrode active material precursor (2).

[0154] The preparation method (2) of the positive electrode active material precursor of the present invention includes the following steps: (S1') introducing a solution containing a transition metal and an alkaline aqueous solution into a reactor to form positive electrode active material precursor seed crystals by a coprecipitation reaction; and (S2') introducing a solution containing a transition metal and an alkaline aqueous solution into a reactor containing positive electrode active material precursor seed crystals to grow positive electrode active material precursor particles by a coprecipitation reaction, wherein step (S1') is performed while maintaining the pH in the range of 9.0 to 11.0 after gradually reducing the pH from 12.0 or more to the range of 9.0 to 11.0, and step (S2') can be performed while maintaining the pH in the range of 9.0 to 11.0 after gradually reducing the pH from the range of 11.5 to 11.7 to the range of 9.0 to 11.0. As described above, the preparation method of the positive electrode active material precursor of the present invention can easily provide the positive electrode active material precursor of the present invention by appropriately adjusting the pH and introducing or not introducing a solution containing ammonium ions.

[0155] The method (2) for preparing a positive electrode active material precursor is a method suitable for preparing a positive electrode active material precursor containing a composite transition metal hydroxide having a composition represented by Formula 2.

[0156] Step (S1′)

[0157] Step (S1') is a step of performing a coprecipitation reaction to form a positive electrode active material precursor seed crystal while introducing a transition metal-containing solution and an alkaline aqueous solution into a reactor. In this case, a continuous filter tank reactor (CFTR) can be used as a reactor. In this case, the transition metal-containing solution and the alkaline aqueous solution can be continuously introduced.

[0158] While initiating a coprecipitation reaction by introducing a transition metal-containing solution and an alkaline aqueous solution, seed cores of positive electrode active material precursor particles in the form of primary particles are formed, wherein the positive electrode active material precursor seed crystals formed in step (S1') may refer to crystals formed by aggregation of seed cores in the form of primary particles. During the coprecipitation reaction in step (S1'), no solution containing ammonium ions is introduced.

[0159] The solution containing a transition metal may contain cations of at least one metal selected from nickel (Ni), manganese (Mn), cobalt (Co), tungsten (W), molybdenum (Mo), chromium (Cr), and aluminum (Al). The solution containing metal ions may include acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, or oxyhydroxides of the above metals, and is not particularly limited as long as it is soluble in water.

[0160] For example, cobalt (Co) may be contained as Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, CoSO4, or Co(SO4)2·7H2O, and any one of them or a mixture of two or more thereof may be used. In addition, nickel (Ni) may be contained as Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, NiSO4, NiSO4·6H2O, a fatty acid nickel salt, or a nickel halide, and any one of them or a mixture of two or more thereof may be used. Moreover, manganese (Mn) may be included as manganese oxides such as Mn2O3, MnO2, and Mn3O4; manganese salts such as MnCO3, Mn(NO3)2, MnSO4, manganese acetate, manganese dicarboxylate, manganese citrate, and fatty acid manganese salts; manganese oxyhydroxide or manganese chloride, and any one of them or a mixture of two or more thereof may be used.

[0161] 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) (for example, M is at least one element selected from Zr, Ti, Mg, Ta, and Nb), a raw material containing the second metal element may be optionally added when preparing the transition metal-containing solution. The raw material containing the second metal element may include an acetate, nitrate, sulfate, halide, sulfide, hydroxide, oxide, or oxyhydroxide containing the second metal element, and any one of these or a mixture of two or more thereof may be used. For example, when the second metal element is Zr, zirconium oxide or the like may be used.

[0162] The alkaline aqueous solution may include at least one selected from hydrates of alkali metals, hydroxides of alkali metals, hydrates of alkaline earth metals, and hydroxides of alkaline earth metals. For example, the alkaline aqueous solution may include NaOH, KOH, or Ca(OH) 2, and as the solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) uniformly miscible with water may be used.

[0163] According to the present invention, step (S1 ') can be carried out while maintaining the pH in the range of 9.0 to 11.0 after gradually reducing the pH from 12.0 or more to the range of 9.0 to 11.0 to form seed crystals. In this case, it may be beneficial to seed crystal formation. When the pH is rapidly reduced in the initial stage of the reaction, the precursor growth reaction is carried out without forming a sufficient amount of seed crystals, the particle size increases at a relatively fast rate, and there is a problem of preparing a precursor with a quality different from that desired. The pH can be adjusted with an alkaline aqueous solution.

[0164] According to the present invention, step (S1') can be performed in an oxidizing atmosphere. In this case, since thin primary particles can be formed and voids are appropriately formed in the core portion, when the positive electrode active material is prepared using the finally prepared positive electrode active material precursor, the density of the active material can be higher.

[0165] Step (S2')

[0166] Step ( S2 ′) is a step of growing positive electrode active material precursor particles in a reactor.

[0167] This is a step of preparing a positive electrode active material precursor using positive electrode active material precursor seed crystals having a uniform particle size obtained in the reactor in step (S1'), wherein positive electrode active material precursor particles are grown by performing a coprecipitation reaction while introducing a transition metal-containing solution and an alkaline aqueous solution into the reactor. During the coprecipitation reaction in step (S1'), an ammonium ion-containing solution is not introduced.

[0168] According to the present invention, step (S2') can be carried out while maintaining the pH in the range of 9.0 to 11.0 after gradually reducing the pH from the range of 11.5 to 11.7 to the range of 9.0 to 11.0. In this case, the growth reaction of the precursor seed crystal formed in step (S1') is carried out, and the positive active material precursor of the present invention can be prepared. In the case where the final pH is lower than the range of 9.0 to 11.0, there is a problem of forming a large amount of fine powder, and in the case where the final pH is higher than the range of 9.0 to 11.0, due to the phenomenon of primary particle aggregation, there is a problem that the positive active material precursor of the present invention cannot be prepared. The pH can be adjusted with an alkaline aqueous solution.

[0169] According to the present invention, step (S2') may be performed in an oxidizing atmosphere to control the optimal primary particle shape and Mn impurities.

[0170] The ammonium ion-containing solution may include at least one selected from NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3. As the solvent, water or a mixture of water and an organic solvent uniformly miscible with water (specifically, alcohol, etc.) may be used.

[0171] positive electrode active material

[0172] The present invention provides a positive electrode, which is a sintered product of a mixture of a positive electrode active material precursor and a lithium raw material. That is, the positive electrode active material can be prepared by mixing the positive electrode active material precursor of the present invention with a lithium raw material and then sintering the mixture. The positive electrode active material can be a positive electrode active material with a high energy density. In addition, since the positive electrode active material is prepared from the positive electrode active material precursor of the present invention, it has no internal defects and can have low resistance. In the case where the positive electrode active material precursor is a high Ni NCM-based positive electrode active material precursor, the positive electrode active material can be a positive electrode active material in the form of a single particle.

[0173] For example, lithium raw materials may include lithium-containing carbonates (e.g., lithium carbonate, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH·H2O), etc.), hydroxides (e.g., lithium hydroxide, etc.), nitrates (e.g., lithium nitrate (LiNO3), etc.) and chlorides (e.g., lithium chloride (LiCl), etc.), and any one of them or a mixture of two or more thereof may be used.

[0174] The mixing of the positive electrode active material precursor and the lithium raw material can be carried out by solid phase mixing, and the mixing ratio of the positive electrode active material precursor and the lithium raw material can be determined within the range that satisfies the atomic fraction of each component in the positive electrode active material finally prepared. For example, the mixing amount of the positive electrode active material precursor and the lithium raw material can be such that the molar ratio of the transition metal: lithium (Li) contained in the positive electrode active material precursor is in the range of 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 raw material are mixed within the above range, a positive electrode active material exhibiting excellent capacity characteristics can be prepared.

[0175] The sintering may be performed at 600 to 1,000° C., preferably 700 to 900° C., and the sintering time may be in the range of 5 to 30 hours, preferably 10 to 20 hours, but the present invention is not limited thereto.

[0176] For example, the positive electrode active material of the present invention can be prepared by the following process: a positive electrode active material precursor and a lithium raw material are mixed once so that the ratio of the total number of moles of transition metals contained in the positive electrode active material precursor to the number of moles of lithium contained in the lithium raw material is in the range of 1:0.95 to 1:1.00, and the mixture is sintered at 850°C to 1,000°C for 5 to 10 hours to prepare a sintered product, and then the sintered product and the lithium raw material are mixed twice so that the ratio of the total number of moles of transition metals contained in the positive electrode active material precursor to the number of moles of lithium contained in the lithium raw material is in the range of 1:0.02 to 1:0.07, and the mixture is sintered at 800°C to 850°C for 5 to 15 hours. In this case, the prepared positive electrode active material can be in the form of single particles.

[0177] The positive electrode active material may have a composition represented by Formula 3 or Formula 4 below.

[0178] [Formula 3]

[0179] Li x1 [Ni a3 Co b3 M1 c3 M2 d3 ]O2

[0180] In formula 3,

[0181] M1 is at least one selected from Mn and Al,

[0182] M2 is at least one selected from Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga and Ca, and

[0183] 0.9 ≤ x1 ≤ 1.2, 0.6 ≤ a3 < 1, 0 < b3 ≤ 0.4, 0 < c3 ≤ 0.4 and 0 ≤ d4 ≤ 0.2.

[0184] a3 represents the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 3, where a3 can satisfy 0.6 ≤ a3 < 1, 0.8 ≤ a3 ≤ 0.98, or 0.85 ≤ a3 ≤ 0.95.

[0185] b3 represents the atomic fraction of cobalt among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 3, where b3 can satisfy 0 < b3 ≤ 0.4, 0.01 ≤ b3 ≤ 0.2, or 0.01 ≤ b3 ≤ 0.15.

[0186] c3 represents the atomic fraction of the M1 element among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 3, where c3 can satisfy 0 < c3 ≤ 0.4, 0.01 ≤ c3 ≤ 0.2, or 0.01 ≤ c3 ≤ 0.15.

[0187] d3 represents the atomic fraction of the M2 element among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 3, where d3 can satisfy 0 ≤ d3 ≤ 0.2, 0 ≤ d3 ≤ 0.1, or 0 ≤ d3 ≤ 0.05.

[0188] [Formula 4]

[0189] Li x2 [Mn a4 Ni b4 Co c4 M d4 O2

[0190] In Formula 4,

[0191] M is at least one selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga, and Ca; and

[0192] 0.9 ≤ x2 ≤ 1.2, 0.5 ≤ a4 < 1, 0 < b4 ≤ 0.5, 0 ≤ c4 < 0.5 and 0 ≤ d4 ≤ 0.2.

[0193] a4 represents the atomic fraction of manganese among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 4, where a4 can satisfy 0.5 ≤ a4 < 1, 0.6 ≤ a4 ≤ 0.95, or 0.65 ≤ a4 ≤ 0.9.

[0194] b4 represents the atomic fraction of nickel among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 4, where b4 can satisfy 0 < b4 ≤ 0.5, 0.05 ≤ b4 ≤ 0.4, or 0.1 ≤ b4 ≤ 0.3%.

[0195] c4 represents the atomic fraction of cobalt in the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 4, wherein c4 may satisfy 0≤c4<0.5, 0≤c4≤0.2, or 0≤c4≤0.15.

[0196] d4 represents the atomic fraction of the M element among the metal elements in the lithium composite transition metal oxide having the composition represented by Formula 4, wherein d4 may satisfy 0≤d4≤0.2, 0≤d4≤0.1, or 0≤d4≤0.05.

[0197] In the case where the positive electrode active material has a composition represented by Formula 3, the positive electrode active material may be a positive electrode active material in the form of a single particle. In the case where the positive electrode active material is a positive electrode active material in the form of a single particle, the average particle size (D 50 ) can be in the range of 1.0 μm to 6.0 μm, specifically can be 1.0 μm or more, 2.0 μm or more, 3.0 μm or more, or 4.0 μm or more, and can be 5.0 μm or less or 6.0 μm or less, and the positive electrode active material can be in an angular shape rather than a spherical shape.

[0198] In the case where the positive electrode active material has a composition represented by Formula 4, the positive electrode active material may be a positive electrode active material in the form of secondary particles. In the case where the positive electrode active material is a positive electrode active material in the form of secondary particles, the average particle size (D 50 ) can be in the range of 9.0μm to 12.0μm, specifically can be 9.0μm or more, 9.1μm or more, 9.2μm or more, 9.3μm or more, 9.4μm or more, 9.5μm or more, 9.6μm or more, 9.7μm or more, 9.8μm or more, or 9.9μm or more, and can be 10.0μm or less, 10.5μm or less, 11.0μm or less, 11.5μm or less, or 12.0μm or less, and the positive electrode active material can have a spherical shape.

[0199] positive electrode

[0200] The present invention provides a positive electrode comprising a positive electrode active material.

[0201] The positive electrode may include a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, wherein the positive electrode active material layer may include a positive electrode active material.

[0202] The positive electrode current collector may include a metal with high conductivity, and is not particularly limited, as long as it is non-reactive within the voltage range of the battery and the positive electrode active material layer is easily adhered thereto. As the positive electrode current collector, for example, stainless steel, aluminum, nickel, titanium, fired carbon, or aluminum or stainless steel surface-treated with one of carbon, nickel, titanium or silver, etc., may be used. Moreover, the positive electrode current collector may generally have a thickness of 3 μm to 500 μm, and microscopic irregularities may be formed on the surface of the current collector to improve the adhesion of the positive electrode active material. The positive electrode current collector may be used, for example, in various shapes, such as a film, a sheet, a foil, a mesh, a porous body, a foam body, and a non-woven fabric body.

[0203] If necessary, the positive electrode active material layer may further include a conductive agent and a binder in addition to the positive electrode active material. In this case, the content of the positive electrode active material may be 80% to 99% by weight, more specifically 85% to 98.5% by weight, based on the total weight of the positive electrode active material layer. Within this range, excellent capacity characteristics may be exhibited.

[0204] The conductive agent is used to provide conductivity to the electrode, wherein any conductive agent can be used without particular limitation, as long as it has suitable electronic conductivity and does not cause adverse chemical changes in the battery. Specific examples of the conductive agent can be graphite, such as natural graphite or artificial graphite; carbon-based materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; powders or fibers of metals such as copper, nickel, aluminum, and silver; conductive tubes, such as carbon nanotubes; conductive whiskers, such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides, such as titanium oxide; or conductive polymers, such as polyphenylene derivatives, and any one of them or a mixture of two or more thereof can be used. The content of the conductive agent can be 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0205] The binder improves the adhesion between the positive active material particles and the adhesion between the positive active material and the current collector. The specific example of the binder can be polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, and a polymer whose hydrogen is replaced by lithium (Li), sodium (Na) or calcium (Ca), or its various copolymers, and any one thereof or a mixture of two or more thereof can be used. Based on the gross weight of the positive active material layer, the content of the binder can be 0.1 wt % to 15 wt %.

[0206] In addition to using the above-mentioned positive electrode active material, the positive electrode can be prepared according to a typical method for preparing a positive electrode. Specifically, a positive electrode active material layer-forming composition prepared by dissolving or dispersing the above-mentioned positive electrode active material and, if necessary, an optional binder, a conductive agent, and a dispersant in a solvent is coated on the positive electrode current collector, and then the positive electrode can be prepared by drying and rolling the coated positive electrode current collector, or the positive electrode active material layer-forming composition can be cast on a separate support and then the film separated from the support is laminated on the positive electrode current collector.

[0207] The solvent may be a commonly used solvent in the art. The solvent may include dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone or water, and any one thereof or a mixture of two or more thereof may be used. Taking into account the coating thickness and manufacturing yield of the slurry, if the solvent can dissolve or disperse the positive electrode active material, conductive agent, binder and dispersant, and can allow for a viscosity that can provide excellent thickness uniformity during subsequent coating for preparing the positive electrode, the amount of the solvent used may be sufficient.

[0208] lithium secondary batteries

[0209] The present invention provides a lithium secondary battery, which includes a positive electrode, a negative electrode, a separator arranged between the positive electrode and the negative electrode, and an electrolyte.

[0210] The lithium secondary battery may further optionally include a battery container accommodating an electrode assembly of a positive electrode, a negative electrode, and a separator, and a sealing member sealing the battery container.

[0211] The negative electrode may include a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.

[0212] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing adverse chemical changes in the battery, and materials such as copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with one of carbon, nickel, titanium or silver, and aluminum-cadmium alloys can be used. Moreover, the negative electrode current collector can generally have a thickness of 3 μm to 500 μm, and similar to the positive electrode current collector, microscopic irregularities can be formed on the surface of the current collector to improve the adhesion of the negative electrode active material. The negative electrode current collector can be used in various shapes, such as a film, sheet, foil, mesh, porous body, foam body, and non-woven fabric body.

[0213] In addition to the negative electrode active material, the negative electrode active material layer may optionally include a binder and a conductive agent.

[0214] As the negative electrode active material, a compound capable of reversibly intercalating and deintercalating lithium can be used. Specific examples of the negative electrode active material may include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fibers, and amorphous carbon; metal compounds that can be alloyed with lithium, such as silicon (Si), aluminum (Al), tin (Sn), lead (Pb), zinc (Zn), bismuth (Bi), indium (In), magnesium (Mg), gallium (Ga), cadmium (Cd), Si alloys, Sn alloys, or Al alloys; metal oxides that may or may not be doped with lithium, such as SiO β (0<β<2), SnO2, vanadium oxide and lithium vanadium oxide; or a composite including a metal compound and a carbonaceous material, such as a Si-C composite or a Sn-C composite, and any one of them or a mixture of two or more thereof can be used. Moreover, a metallic lithium film can be used as a negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon can be used as carbon materials. Typical examples of low-crystalline carbon can be soft carbon and hard carbon, and typical examples of high-crystalline carbon can be irregular, plate-shaped, flaky, spherical or fibrous natural graphite or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fibers, mesophase carbon microbeads, mesophase pitch and high-temperature sintered carbon such as coke derived from petroleum or coal tar pitch. The content of the negative electrode active material can be 80% by weight to 99% by weight based on the total weight of the negative electrode active material layer.

[0215] The binder of the negative electrode active material layer is a component that helps to bind the conductive agent, the active material and the current collector, wherein the binder is generally 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 the binder can be polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, acrylonitrile-butadiene rubber, fluororubber and various copolymers thereof.

[0216] The conductive agent of the negative electrode active material layer is a component for further improving the conductivity of the negative electrode active material, wherein the content of the conductive agent may be 10% by weight or less, preferably 5% by weight or less, based on the total weight of the negative electrode active material layer. The conductive agent is not particularly limited as long as it has conductivity and does not cause adverse chemical changes in the battery, and for example, conductive materials such as: graphite, such as natural graphite or artificial graphite; carbon black, such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers, such as carbon fibers or metal fibers; fluorocarbons; metal powders, such as aluminum powder and nickel powder; conductive whiskers, such as zinc oxide whiskers and potassium titanate whiskers; conductive metal oxides, such as titanium oxide; or polyphenylene derivatives can be used.

[0217] The negative electrode can be prepared by coating a negative electrode active material layer forming composition prepared by dissolving or dispersing an optional binder and a conductive agent and a negative electrode active material in a solvent on a negative electrode collector and drying the coated negative electrode collector, or can be prepared by casting the negative electrode active material layer forming composition on a separate support and then laminating the film separated from the support on the negative electrode collector.

[0218] The negative electrode and the positive electrode are separated by the diaphragm and a path for the movement of lithium ions is provided, wherein any diaphragm can be used as a diaphragm without particular limitation, as long as it is commonly used in lithium secondary batteries, in particular, a diaphragm having high moisture retention and low resistance to the transfer of electrolyte ions can be used. Specifically, a porous polymer film can be used, for example, a porous polymer film prepared by a polyolefin polymer (such as ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer and ethylene / methacrylate copolymer), or a laminated structure with more than two layers thereof. Moreover, a typical porous nonwoven fabric can be used, for example, a nonwoven fabric formed by high melting point glass fiber or polyethylene terephthalate fiber. In addition, a coated diaphragm including a ceramic component or a polymeric material can be used to ensure heat resistance or mechanical strength, and a diaphragm with a single layer or multilayer structure can be optionally used.

[0219] The electrolyte may include an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel polymer electrolyte, a solid inorganic electrolyte or a molten inorganic electrolyte that can be used to prepare a lithium secondary battery, but the present invention is not limited thereto. As a specific example, the electrolyte may include an organic solvent and a lithium salt.

[0220] Any organic solvent can be used as an organic solvent without particular limitation, as long as it can act as a medium through which ions participating in the electrochemical reaction of the battery can move. Specifically, as an organic solvent, ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone and ε-caprolactone can be used; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; or carbonate solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC) and propylene carbonate (PC); alcohol solvents such as ethanol and isopropanol; nitriles such as R-CN (wherein R is a linear, branched or cyclic C2-C20 hydrocarbon group, and may include a double bond aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes. Among these solvents, carbonate solvents are preferred, and more preferred are mixtures of cyclic carbonates (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant and linear carbonate compounds (e.g., ethyl methyl carbonate, dimethyl carbonate or diethyl carbonate) having low viscosity, which can improve the charge / discharge performance of the battery.

[0221] The lithium salt can be used without particular limitation as long as it is a compound capable of providing lithium ions for lithium secondary batteries. Specifically, the anion of the lithium salt can be selected from 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 -At least one of the group consisting of, and as the lithium salt, LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI or LiB(C2O4)2 can be used. The lithium salt can be used in a concentration range of 0.1M to 2.0M. If the concentration of the lithium salt is included in the above range, since the electrolyte can have appropriate conductivity and viscosity, excellent electrolyte performance can be obtained and lithium ions can be efficiently moved.

[0222] In order to improve the life characteristics of the battery, suppress the reduction of the battery capacity and improve the discharge capacity of the battery, in addition to the electrolyte components, the electrolyte may further include at least one additive, such as a halogenated alkylene carbonate compound such as difluoroethylene carbonate, pyridine, triethyl phosphite, triethanolamine, cyclic ether, ethylenediamine, n-glyme dimethyl ether, hexamethylphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol or aluminum chloride. In this case, the content of the additive may be 0.1 wt % to 5 wt % based on the total weight of the electrolyte.

[0223] Since the lithium secondary battery including the positive electrode active material of the present invention exhibits excellent capacity characteristics, initial efficiency, resistance characteristics and life characteristics, the lithium secondary battery is suitable for portable devices such as mobile phones, notebook computers and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0224] The shape of the lithium secondary battery of the present invention is not particularly limited, but a cylindrical type using a can, a prismatic type, a pouch type, or a coin type may be used.

[0225] The lithium secondary battery of the present invention can be used not only in a battery cell used as a power source for small devices but also as a unit cell in a medium or large battery module including a plurality of battery cells.

[0226] Therefore, a battery module including a lithium secondary battery as a unit cell and a battery pack including the battery module are provided.

[0227] The battery module or battery pack may be used as a power source for at least one of the following medium to large devices: a power tool; an electric vehicle, including an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0228] Hereinafter, the embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in many different forms and should not be construed as being limited to the embodiments described herein.

[0229] Example 1

[0230] NiSO4, CoSO4, and MnSO4 were introduced into distilled water at a molar ratio of Ni:Co:Mn of 88.5:3.5:8.0 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a NaOH aqueous solution with a concentration of 7.96 M and an NH4OH aqueous solution with a concentration of 5.08 M were prepared.

[0231] like Figure 1 As shown, a container containing a transition metal solution, a container containing an aqueous NaOH solution, and a container containing an aqueous NH4OH solution were connected to the 100 L reactor, respectively.

[0232] 28.59 L of deionized water, 0.035 L of an aqueous NaOH solution, and 0.216 L of an aqueous NH 4 OH solution were introduced into the reactor, and then dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0233] 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. Figure 2 As shown in (A), the pH is gradually lowered, an aqueous NaOH solution is added with the participation of a pH sensor, and a co-precipitation reaction is carried out for 1.5 hours to form positive electrode active material precursor seed crystals, while the continuous mill is operated to repeat the following process: the positive electrode active material precursor seed crystals are discharged from the reactor into the continuous mill at a rate of 1,000 L / hr ([reactor capacity × 10] / [hr]) and the positive electrode active material precursor seed crystals are reintroduced from the continuous mill into the reactor at a rate of 1,000 L / hr ([reactor capacity × 10] / [hr]).

[0234] 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. Figure 2As shown in (A), the pH is gradually increased, and an aqueous NaOH solution is added with the participation of a pH sensor, and a coprecipitation reaction is carried out for 4.5 hours to allow the positive electrode active material precursor particles to grow. At the same time, the continuous mill is operated to repeat the following process: the positive electrode active material precursor seeds are discharged from the reactor into the continuous mill at a rate of 1,000 L / hr ([reactor capacity × 10] / [hr]) and the positive electrode active material precursor seeds are reintroduced from the continuous mill into the reactor at a rate of 1,000 L / hr ([reactor capacity × 10] / [hr]).

[0235] 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. Figure 2 As shown in (A), the pH was gradually increased, and a coprecipitation reaction was performed while adding an aqueous NaOH solution with the aid of a pH sensor. The total reaction time was 32 hours to grow positive electrode active material precursor particles. For reference, when the 100L reactor was full, the filtration system within the reactor was operated to continuously introduce a transition metal solution, aqueous NH4OH solution, and aqueous NaOH solution, while continuously discharging the solvent after the reaction to the outside of the reactor.

[0236] The overall composition of the positive electrode active material precursor particles prepared in this way is Ni 0.885 Co 0.035 Mn 0.08 (OH)2, average particle size (D 50 ) is 3.38μm.

[0237] Example 2

[0238] MnSO4 and NiSO4 were introduced into distilled water at a molar ratio of Mn:Ni of 65:35 to prepare a transition metal-containing solution having a concentration of 2.4 M. In addition, a 25 wt% aqueous NaOH solution and a 9 M NH4OH aqueous solution were prepared.

[0239] A container containing the transition metal-containing solution and a container containing the NaOH aqueous solution were connected to the 100 L CFTR reactor 1, respectively.

[0240] 40 L of deionized water, 50 mL of NaOH aqueous solution, and 52 mL of NH 4 OH aqueous solution were introduced into the CFTR reactor 1 to adjust the pH to 12, and dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0241] Thereafter, nitrogen and oxygen were 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. In this case, a coprecipitation reaction was carried out for 20 hours while adding an aqueous NaOH solution together with the transition metal-containing solution with the participation of a pH sensor to form positive electrode active material precursor seed crystals, and the amount of the aqueous NaOH solution added was such that the pH gradually decreased from 12 to 10 within 2 hours from the time of addition of the transition metal-containing solution, and the pH was maintained at 10 for 18 hours thereafter.

[0242] When the CFTR reactor 1 is full, the filtration system located in the reactor is operated to continuously discharge the solvent after the reaction is completed to the outside of the reactor, and at the same time, the coprecipitation reaction is carried out while continuously introducing the transition metal-containing solution and the NaOH aqueous solution.

[0243] The average particle size of the positive electrode active material precursor seed crystals formed by the reaction (D 50 ) is 4.0 μm, and the average cross-sectional area of ​​the primary particles is 0.0194 μm 2 .

[0244] The container containing the transition metal-containing solution and the container containing the NaOH aqueous solution were connected to the 100 L CFTR reactor 2, respectively.

[0245] Thereafter, 3.2 kg of the prepared positive electrode active material precursor seed crystals, 45 L of deionized water, and 1.8 L of NH4OH aqueous solution were introduced into the CFTR reactor 2 to adjust the pH to a range of 11.5 to 11.6, and the dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0246] Thereafter, nitrogen and oxygen were 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. In this case, a coprecipitation reaction was carried out for 26 hours while adding an aqueous NaOH solution together with the transition metal-containing solution with the participation of a pH sensor to grow positive electrode active material precursor particles, and the amount of the aqueous NaOH solution added was such that the pH gradually decreased from the range of 11.5 to 11.6 to 10 within 2 hours from the time of addition of the transition metal-containing solution, and the pH was maintained at 10 for 24 hours thereafter.

[0247] When the CFTR reactor 2 is full, the filtration system in the reactor is operated to continuously discharge the solvent after the reaction to the outside of the reactor, while the transition metal solution and the NaOH aqueous solution are continuously introduced to carry out the coprecipitation reaction. The overall composition of the positive electrode active material precursor particles prepared in this way is Mn0.65 Ni 0.35 (OH)2, average particle size (D 50 ) is 10.00μm.

[0248] Example 3

[0249] MnSO4 and NiSO4 were introduced into distilled water at a molar ratio of Mn:Ni of 65:35 to prepare a transition metal-containing solution having a concentration of 2.4 M. In addition, a 25 wt% aqueous NaOH solution and a 9 M NH4OH aqueous solution were prepared.

[0250] A container containing the transition metal-containing solution and a container containing the NaOH aqueous solution were connected to the 10 L CFTR reactor 1, respectively.

[0251] 5 L of deionized water, 6.3 mL of NaOH aqueous solution, and 6.4 mL of NH 4 OH aqueous solution were introduced into the CFTR reactor to adjust the pH to 12, and dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0252] Thereafter, nitrogen and oxygen were introduced into the CFTR reactor 1 at a volume ratio of 5:0.04 to form a weakly oxidizing atmosphere, and a transition metal-containing solution was continuously introduced into the reactor at a rate of 0.42 L / hr. In this case, a coprecipitation reaction was conducted for 24 hours while adding an aqueous NaOH solution together with the transition metal-containing solution in the presence of a pH sensor to form positive electrode active material precursor seed crystals. The amount of NaOH aqueous solution added was such that the pH gradually decreased from 12 to 10 within 2 hours from the time of addition of the transition metal-containing solution, and the pH was maintained at 10 for 22 hours thereafter.

[0253] When the CFTR reactor 1 is full, the filtration system located in the reactor is operated to continuously discharge the solvent after the reaction is completed to the outside of the reactor, and at the same time, the coprecipitation reaction is carried out while continuously introducing the transition metal-containing solution and the NaOH aqueous solution.

[0254] In addition, while the reaction proceeds, the atmosphere in the CFTR reactor is adjusted so that the ratio of nitrogen to oxygen is in the range of 5:0.04 to 5:0.1 until the end of the reaction to obtain the desired primary particle shape.

[0255] The average particle size of the positive electrode active material precursor seed crystals formed by the reaction (D 50 ) is 4.0 μm, and the average cross-sectional area of ​​the primary particles is 0.0199 μm 2 .

[0256] The container containing the transition metal-containing solution and the container containing the NaOH aqueous solution were connected to the 10 L CFTR reactor 2, respectively.

[0257] Thereafter, 0.32 kg of the prepared positive electrode active material precursor seed crystals, 6 L of deionized water, and 1.45 mL of NH 4 OH aqueous solution were introduced into the CFTR reactor 2 to adjust the pH to a range of 11.5 to 11.6, and the dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0258] Thereafter, nitrogen and oxygen were introduced into the CFTR reactor 2 at a volume ratio of 5:0.04 to form a weakly oxidizing atmosphere, and a transition metal-containing solution was continuously introduced into the reactor at a rate of 0.83 L / hr. In this case, a coprecipitation reaction was carried out for 20 hours while adding an aqueous NaOH solution together with the transition metal-containing solution in the presence of a pH sensor to grow positive electrode active material precursor particles. The amount of NaOH aqueous solution added was such that the pH gradually decreased from the range of 11.5 to 11.6 to 10 within 2 hours from the time of addition of the transition metal-containing solution, and the pH was maintained at 10 for 18 hours thereafter.

[0259] When the CFTR reactor 2 is full, the filtration system located in the reactor is operated to continuously discharge the solvent after the reaction is completed to the outside of the reactor, and at the same time, the coprecipitation reaction is carried out while continuously introducing the transition metal-containing solution and the NaOH aqueous solution.

[0260] The overall composition of the positive electrode active material precursor particles prepared in this way is Mn 0.65 Ni 0.35 (OH)2, average particle size (D 50 ) is 9.95μm.

[0261] Comparative Example 1

[0262] NiSO4, CoSO4, and MnSO4 were introduced into distilled water at a molar ratio of Ni:Co:Mn of 88.5:3.5:8.0 to prepare a transition metal-containing solution with a concentration of 2.4 M. In addition, a NaOH aqueous solution with a concentration of 7.96 M and an NH4OH aqueous solution with a concentration of 5.08 M were prepared.

[0263] like Figure 1 As shown, a container containing a transition metal solution, a container containing an aqueous NaOH solution, and a container containing an aqueous NH4OH solution were connected to the 100 L reactor, respectively.

[0264] 28.59 L of deionized water, 0.035 L of an aqueous NaOH solution, and 0.216 L of an aqueous NH 4 OH solution were introduced into the reactor, and then dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0265] 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. Figure 2 The pH was adjusted as shown in (B), and a coprecipitation reaction was conducted for 1.5 hours while adding an aqueous NaOH solution with the aid of a pH sensor to form positive electrode active material precursor seed crystals. Subsequently, when the 100L reactor was full, the filtration system located in the reactor was operated to continuously drain the solvent after the reaction to the outside of the reactor. The coprecipitation reaction was then conducted while continuously introducing a transition metal-containing solution, an aqueous NH4OH solution, and an aqueous NaOH solution for a total reaction time of 32 hours to grow positive electrode active material precursor particles.

[0266] Comparative Example 2

[0267] MnSO4 and NiSO4 were introduced into distilled water at a molar ratio of Mn:Ni of 65:35 to prepare a transition metal-containing solution having a concentration of 2.4 M. In addition, a 25 wt% aqueous NaOH solution and a 9 M NH4OH aqueous solution were prepared.

[0268] The container containing the transition metal-containing solution and the container containing the NaOH aqueous solution were connected to the 10 L CFTR reactor, respectively.

[0269] 3.6 L of deionized water and 325 mL of NaOH aqueous solution were introduced into the CFTR reactor to adjust the pH to 11, and dissolved oxygen in the water was removed by purging the reactor with nitrogen to form a non-oxidizing atmosphere in the reactor.

[0270] Thereafter, nitrogen gas was introduced into the CFTR reactor to form a non-oxidizing atmosphere, and a transition metal-containing solution was continuously introduced into the reactor at a rate of 0.82 L / hr. In this case, a coprecipitation reaction was conducted for 43 hours while adding an aqueous NaOH solution along with the transition metal-containing solution in the presence of a pH sensor to form a positive electrode active material precursor. The amount of NaOH added was such that the pH gradually decreased from 11 to 10 over 2 hours from the time of addition of the transition metal-containing solution, and the pH was maintained at 10.5 for 41 hours thereafter.

[0271] When the CFTR reactor is full, the filtration system located in the reactor is operated to continuously discharge the solvent after the reaction is completed to the outside of the reactor, and at the same time, the coprecipitation reaction is carried out while continuously introducing the transition metal-containing solution and the NaOH aqueous solution.

[0272] The overall composition of the positive electrode active material precursor particles prepared in this way is Mn 0.65 Ni 0.35 (OH)2, average particle size (D 50 ) is 11.9μm.

[0273] Experimental Example 1

[0274] Each of the positive active material precursors prepared in Examples 1 to 3 and Comparative Examples 1 and 2 was cut using an ion mill at a power of 6 KeV to obtain a cross-sectional sample, and a scanning electron microscope (SEM) was used to obtain a cross-sectional SEM image. Figure 3 : are cross-sectional SEM images of the positive electrode active material precursors prepared in Examples 1 to 3 and Comparative Examples 1 and 2. Specifically, Figure 3 (A), 3(B), 3(C), 3(D) and 3(E) are cross-sectional SEM images of the positive electrode active material precursors prepared in Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2, respectively.

[0275] The cross-sectional SEM images were analyzed using Image J to obtain the average cross-sectional area (A1) of the primary particles of the core portion and the average cross-sectional area (A2) of the primary particles of the shell portion of each of the positive electrode active material precursors prepared in Examples and Comparative Examples, and the values ​​are presented in Table 1 below. In addition, the ratio of the average cross-sectional area of ​​the primary particles of the shell portion to the average cross-sectional area of ​​the primary particles of the core portion (A2 / A1) was calculated and presented in Table 1 below.

[0276] In this case, the average cross-sectional area of ​​the primary particles is a value obtained by dividing the total cross-sectional area of ​​tens to hundreds of primary particles by the number of primary particles.

[0277] [Table 1]

[0278]

[0279] Experimental Example 2

[0280] Each of the positive electrode active material precursors prepared in Examples and Comparative Examples was cut using an ion mill at a power of 6 KeV to obtain a cross-sectional sample, and a scanning electron microscope (SEM) was used to obtain a cross-sectional SEM image.

[0281] The cross-sectional SEM images were analyzed using Image J. Therefore, the percentage (%) of the cross-sectional area of ​​all pores in the core portion to the cross-sectional area of ​​the core portion, the percentage (%) of the cross-sectional area of ​​all pores in the shell portion to the cross-sectional area of ​​the shell portion, and the percentage (%) of the cross-sectional area of ​​the core portion to the cross-sectional area of ​​the positive electrode active material precursor are presented in Table 2 below.

[0282] Figure 4 (A) to 4(C) were analyzed by using Image J Figure 3 (A) is an image used to obtain the percentage of the cross-sectional area of ​​all pores present in the positive electrode active material precursor in the total cross-sectional area of ​​the positive electrode active material precursor, (B) is an image used to obtain the percentage of the cross-sectional area of ​​the core part in the cross-sectional area of ​​the positive electrode active material precursor, and (C) is an image used to obtain the percentage of the cross-sectional area of ​​all pores present in the core part in the cross-sectional area of ​​the core part.

[0283] Figure 5 (A) to 5(C) were analyzed by using Image J Figure 3 (A) is an image used to obtain the percentage of the cross-sectional area of ​​all pores present in the positive electrode active material precursor in the total cross-sectional area of ​​the positive electrode active material precursor, (B) is an image used to obtain the percentage of the cross-sectional area of ​​the core part in the cross-sectional area of ​​the positive electrode active material precursor, and (C) is an image used to obtain the percentage of the cross-sectional area of ​​all pores present in the core part in the cross-sectional area of ​​the core part.

[0284] For reference, the percentage (%) of the cross-sectional area of ​​all pores present in the core portion to the cross-sectional area of ​​the core portion is a value calculated by subtracting the percentage (%) of the cross-sectional area of ​​all pores present in the shell portion to the cross-sectional area of ​​the shell portion from the percentage (%) of the cross-sectional area of ​​all pores present in the positive electrode active material precursor to the total cross-sectional area of ​​the positive electrode active material precursor.

[0285] [Table 2]

[0286]

[0287] Experimental Example 3

[0288] 1) Check the span value of the positive electrode active material precursor

[0289] The D5, D6, and D7 of each of the positive electrode active material precursors of Examples 1 to 3 and Comparative Examples 1 and 2 were measured using a particle size analyzer (S-3500, Microtrac). 50 and D 95, and the span value of the positive electrode active material precursor was calculated according to the following equation 4 and presented in the following Table 3.

[0290] [Equation 4]

[0291] Span = (D 95 -D5) / D 50

[0292] 2) Check the proportion of abnormal particles and the aspect ratio and circularity of the particles

[0293] The proportion of abnormal particles, as well as the aspect ratio and circularity of the particles, can be measured from the segmented images divided into each secondary particle unit, obtained by image processing of scanning electron microscope (SEM) images using an artificial intelligence model. To explain this, Figure 6 Figure 2 shows (A) a SEM image and (B) a segmented image obtained by image processing the SEM image. After obtaining a scanning electron microscope (SEM) image of the cathode material powder to be tested, a segmented image can be obtained by inputting the obtained SEM image into a U-NET structure to generate a binary image, then converting the binary image into a distance-converted image based on a distance conversion algorithm, filtering the binary image using a set threshold based on the distance-converted image, identifying multiple objects contained in the filtered binary image, and then segmenting the SEM image into secondary particle units based on the multiple objects.

[0294] exist Figure 6 In the segmented image of (B), as shown by the dotted circle, when two or more particles (other than spherical secondary particles) aggregate and adhere, they are allowed to be identified as abnormal particles, and the ratio of the number of abnormal particles to the total number of particles is confirmed and presented in Table 3 below.

[0295] In addition, if Figure 7 As shown in the image, the short axis and the long axis were set for each secondary particle unit in the segmented image, and the aspect ratio was calculated according to the following equation 5 and presented in the following Table 3. Figure 7 : is a diagram showing the definition of the minor axis and the major axis used to calculate the aspect ratio of a particle.

[0296] [Equation 5]

[0297]

[0298] Furthermore, the circularity was calculated for each secondary particle unit in the segmented image according to the following Equation 6 and is presented in Table 3 below.

[0299] [Equation 6]

[0300] Circularity = 4πA / P 2

[0301] In Equation 6, A is the area of ​​each secondary particle measured in the segmented image, and P is the perimeter of each secondary particle measured in the segmented image.

[0302] For reference, with respect to the aspect ratio and circularity, it can be considered that as the aspect ratio and circularity are each closer to 1.0, the sphericity is more excellent.

[0303] [Table 3]

[0304] category span Abnormal particles (%) Aspect ratio Circularity Example 1 0.96 - 1.3174 0.8466 Example 2 0.58 3.1833 1.1388 0.8731 Example 3 0.58 4.5600 1.1472 0.8196 Comparative Example 1 1.32 - 1.3533 0.8090 Comparative Example 2 0.85 19.3400 1.2956 0.7215

[0305] Referring to Table 3, it can be confirmed that the high-Ni NCM-based positive electrode active material precursor of Example 1 has a smaller span value than that of the high-Ni NCM-based positive electrode active material precursor of Comparative Example 1, and its aspect ratio and circularity are close to 1. In addition, it can be confirmed that the Mn-rich NCM-based positive electrode active material precursors of Examples 2 and 3 have smaller span values ​​than that of the Mn-rich NCM-based positive electrode active material precursor of Comparative Example 2, and not only are the number of abnormal particles smaller, but also their aspect ratios and circularities are close to 1.

[0306] Therefore, it can be confirmed that the positive electrode active material precursor of the present invention has a uniform particle size and excellent sphericity.

[0307] Experimental Example 4

[0308] The positive electrode active material precursors of Example 1 and Comparative Example 1 were each mixed with LiOH so that the molar ratio of the total number of moles of transition metals (Ni + Co + Mn) contained in the positive electrode active material precursor to the molar number of lithium contained in LiOH was 1:0.98, and the mixture was primarily sintered at 895° C. for 6 hours to prepare a primary sintered product. The primary sintered product and LiOH were mixed so that the molar ratio of the total number of moles of transition metals (Ni + Co + Mn) contained in the positive electrode active material precursor to the lithium contained in LiOH was 1:0.04, and the mixture was secondary sintered at 820° C. for 9 hours to prepare a lithium composite transition metal oxide (positive electrode active material) in the form of single particles having an average particle diameter of 4.8 μm.

[0309] Figure 8 (A) A SEM image of a positive electrode active material prepared using the positive electrode active material precursor of Example 1, and (B) a SEM image of a positive electrode active material prepared using the positive electrode active material precursor of Comparative Example 1 are shown.

[0310] Each positive electrode active material prepared by the above method, a conductive agent (carbon black), and a binder (PVdF) were mixed in an N-methyl-2-pyrrolidone (NMP) solvent at a weight ratio of 95:2:3 to prepare a positive electrode slurry. One surface of an aluminum current collector was coated with the positive electrode slurry, dried at 130°C, and then roll-pressed to prepare each positive electrode.

[0311] An electrode assembly was prepared by disposing a separator between the positive electrode and the negative electrode prepared as described above, and then the electrode assembly was placed in a battery case, and then an electrolyte solution was injected into the battery case to prepare a 2032-type coin cell lithium secondary battery.

[0312] In this case, a lithium (Li) metal disk was used as the negative electrode, and an electrolyte solution in which 1M LiPF6 was dissolved in an organic solvent (ethylene carbonate:ethylmethyl carbonate:diethyl carbonate mixed in a volume ratio of 3:3:4) was used as the electrolyte solution.

[0313] Each lithium secondary battery prepared as described above was charged to 4.25 V at a constant current of 0.2 C in a constant current / constant voltage (CC / CV) mode (CV 0.05 C) at 25° C., and then discharged to 2.5 V at a constant current of 0.2 C in CC mode to measure the initial charge capacity and discharge capacity. The measurement results are presented in Table 4 below.

[0314] Furthermore, each lithium secondary battery prepared as described above was charged to 4.4V at a constant current of 0.1C in CC / CV mode (CV 0.05C) at 45°C, and then discharged to 2.5V at a constant current of 0.1C in CC mode. Thereafter, charging (CV 0.05C) to 4.4V in a constant current CC / CV mode of 0.5C and then discharging to 2.5V in a constant current CC mode of 1.0C was set as 1 cycle, and the cycle was repeated 50 times. In this case, the percentage of the DCIR obtained by dividing the voltage drop (ΔV) for 60 seconds in the 50th discharge cycle by the current and the DCIR obtained by dividing the voltage drop (ΔV) for 60 seconds in the 1st discharge cycle by the current was defined as the resistance increase rate, and the resistance increase rate is presented in Table 4 below.

[0315] [Table 4]

[0316]

[0317] Referring to Table 4, for a battery including a positive electrode active material prepared by using the positive electrode active material precursor of Example 1, it can be confirmed that it has a higher capacity retention rate and a significantly lower resistance increase rate than a battery including a positive electrode active material prepared by using the positive electrode active material precursor of Comparative Example 1 (wherein the ratio 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 is small, less than 3.00).

[0318] Therefore, in the positive electrode active material precursor of the present invention, it can be understood that when the mixture of the positive electrode active material precursor and the lithium-containing raw material is sintered, the high Ni NCM-based positive electrode active material precursor can easily form a positive electrode active material in the form of a single particle with a high single particle formation degree, and since lithium easily diffuses into the core part, it can provide a positive electrode active material that can realize a battery with excellent capacity characteristics and resistance characteristics.

[0319] [Description of symbol]

[0320] 100: Reactor

[0321] 200: Continuous grinding machine

Claims

1. A precursor of a positive electrode active material including a composite transition metal hydroxide, the composite transition metal hydroxide comprising: A core portion including first primary particles; and A shell portion formed on the core portion and including second primary particles, in, In a cross-section of the precursor of the positive electrode active material, 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 in the range of 3.00 to 10.

0.

2. The positive electrode active material precursor according to claim 1, wherein The average particle size (D 50 ) is 2.0μm to 11.0μm.

3. The positive electrode active material precursor according to claim 1, wherein The core portion is in the form of spherical secondary particles formed by aggregation 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 Formula 1: [Formula 1] [Ni a1 Co b1 M1 c1 M2 d1 ](OH)2 Wherein, in Formula 1, M1 is at least one selected from manganese (Mn) and aluminum (Al), M2 is at least one selected from yttrium (Y), zirconium (Zr), boron (B), titanium (Ti), tungsten (W), niobium (Nb), strontium (Sr), molybdenum (Mo), magnesium (Mg), phosphorus (P), vanadium (V), tantalum (Ta), gallium (Ga) and calcium (Ca), and 0.6 ≤ a1 < 1, 0 < b1 ≤ 0.4, 0 < c1 ≤ 0.4 and 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 Formula 2: [Formula 2] [Mn a2 Ni b2 What c2 M d2 ](OH)2 Wherein, in Formula 2, M is at least one selected from Al, Y, Zr, B, Ti, W, Nb, Sr, Mo, Mg, P, V, Ta, Ga and Ca, and 0.5 ≤ a2 < 1, 0 < b2 ≤ 0.5, 0 ≤ c2 < 0.5 and 0 ≤ d2 ≤ 0.

2.

6. The positive electrode active material precursor according to claim 4, wherein In a cross-section of the precursor of the positive electrode active material, 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 in the range of 4.60 to 5.00, and Average particle size (D 50 ) is in the range of 2.00μm to 5.00μm.

7. The positive electrode active material precursor according to claim 5, wherein In a cross-section of the precursor of the positive electrode active material, 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 in the range of 3.00 to 4.60, and Average particle size (D 50 ) is in the range of 9.50μm to 11.00μm.

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

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

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

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

12. The positive electrode active material precursor according to claim 1, wherein In a cross-section of the precursor of the positive electrode active material, the difference (C - S) between the percentage (C) of the cross-sectional area of all pores present in the core portion in the cross-sectional area of the core portion and the percentage (S) of the cross-sectional area of all pores present in the shell portion in the cross-sectional area of the shell portion is in the range of 5.00% to 28.00%.

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

14. A method for preparing the positive electrode active material precursor according to claim 1 using a reaction apparatus connected to a reactor and a continuous grinder, the method comprising the following steps: (S1) introducing a transition metal-containing solution, an ammonium ion-containing solution, and an alkaline aqueous solution into the reactor to form positive electrode active material precursor seed crystals through a coprecipitation reaction, while operating the continuous mill, and repeatedly discharging the positive electrode active material precursor seed crystals from the reactor into the continuous mill and reintroducing the positive electrode active material precursor seed crystals from the continuous mill into the reactor; as well as (S2) stopping the operation of the continuous grinder and growing positive electrode active material precursor particles in the reactor, wherein step (S1) is performed while gradually lowering the pH, and Step (S2) is performed while gradually increasing the pH.

15. The method according to claim 14, wherein Step (S1) is performed while gradually lowering the pH within the range of 12.6 to 11.

2.

16. The method according to claim 14, wherein Step (S2) is performed while gradually increasing the pH within the range of 11.2 to 12.

6.

17. A method for preparing the positive electrode active material precursor according to claim 1, the method comprising the following steps: (S1′) introducing a transition metal-containing solution and an alkaline aqueous solution into a reactor to form positive electrode active material precursor seed crystals through a coprecipitation reaction; and (S2′) introducing a solution containing a transition metal and an alkaline aqueous solution into the reactor containing the positive electrode active material precursor seed crystals to grow positive electrode active material precursor particles through a coprecipitation reaction, wherein step (S1′) is performed while maintaining the pH in the range of 9.0 to 11.0 after gradually lowering the pH from 12.0 or more to the range of 9.0 to 11.0, and The step (S2') is performed while maintaining the pH in the range of 9.0 to 11.0 after gradually lowering the pH from the range of 11.5 to 11.7 to the range of 9.0 to 11.

0.

18. The method according to claim 17, wherein Step (S1') is performed in an oxidizing atmosphere.

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