Cathode active material precursor

Abstract

The present invention relates to a cathode active material precursor having improved quality by suppressing the formation of internal pores. Specifically, the present invention relates to a cathode active material precursor comprising: a core part which is a secondary particle in which a plurality of primary particles are aggregated, and which includes nickel, cobalt and manganese; and a shell part which encompasses the surface of the core part and which includes nickel, cobalt and manganese, wherein the ratio (b / a) of the primary particle size (b) of the shell part to the primary particle size (a) of the core part is 0.7-1.0.

Description

positive electrode active material precursor

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0189753 filed on December 18, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a positive electrode active material precursor.

[0005]

[0006] With the recent increase in technological development and demand for mobile devices and electric vehicles, the demand for rechargeable batteries as an energy source is rapidly rising. Among these rechargeable batteries, lithium-ion batteries, which possess high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0007] Lithium transition metal oxides, such as lithium cobalt oxide like LiCoO2, lithium nickel oxide like LiNiO2, lithium manganese oxide like LiMnO2 or LiMn2O4, and lithium iron phosphate compounds like LiFePO4, have been developed as cathode active materials for lithium secondary batteries, and recently, Li[Ni a Co b Mn c ]O2, Li[Ni a Co b Al c ]O2, Li[Ni a Co b Mn c Al d Lithium composite transition metal oxides containing two or more transition metals, such as O2, have been developed and are widely used.

[0008] Lithium composite transition metal oxides containing two or more transition metals developed to date are typically manufactured in the form of spherical secondary particles formed by the aggregation of tens to hundreds of primary particles. However, physical properties such as lithium ion mobility and electrolyte impregnation vary depending on the orientation of the primary particles or the shape (aspect ratio) of the primary particles. Accordingly, research is being conducted to improve the performance of cathode active materials by controlling the particle structure of the cathode active material particles.

[0009] In this regard, pore bands are sometimes formed during the manufacture of cathode active material precursors. Conventionally, dopants were used to control pores, but technologies are currently being developed to control pores solely through the shape of the precursor itself, without the aid of dopants.

[0010]

[0011] The problem to be solved by the present invention is to provide a positive electrode active material precursor with improved quality by controlling the size ratio of primary particles in the core and shell portions of the positive electrode active material precursor to suppress the formation of internal pores in the precursor.

[0012]

[0013] (1) The present invention provides a positive electrode active material precursor comprising: a core portion comprising nickel, cobalt, and manganese, which is a secondary particle formed by the aggregation of a plurality of primary particles; and a shell portion comprising nickel, cobalt, and manganese, which surrounds the surface of the core portion, wherein the ratio (b / a) of the primary particle size (b) of the shell portion to the primary particle size (a) of the core portion is 0.7 or more and 1.0 or less, and the primary particle size is calculated through the following formula 1.

[0014] [Equation 1]

[0015]

[0016] In Equation 1 above, the area of ​​the primary particle is the area obtained by approximating the primary particle as an ellipse from the segmentation image partitioned by primary particle unit, obtained by image processing of the SEM image (unit: μm). 2 ) and the diameter of the primary particle is the diameter of a circle having the same area as the area of ​​the primary particle (unit: μm).

[0017] (2) The present invention provides a positive electrode active material precursor according to (1) above, wherein the primary particle size of the core portion is 0.1 μm or more and 0.25 μm or less.

[0018] (3) The present invention provides a positive electrode active material precursor according to (1) or (2) above, wherein the primary particle size of the shell portion is 0.1 μm or more and 0.25 μm or less.

[0019] (4) In any one of (1) to (3) above, the present invention is such that the average particle size (D of the core part) of the core part is 50 ) provides a positive electrode active material precursor having a size of 3㎛ or more and 6㎛ or less.

[0020] (5) The present invention provides a positive active material precursor in any one of (1) to (4), wherein the thickness of the shell portion is 25% or more and 50% or less of the total particle size of the precursor.

[0021] (6) In any one of (1) to (5) above, the present invention is an average particle size (D) of the positive electrode active material precursor. 50 ) provides a positive electrode active material precursor having a size of 10㎛ or more and 16㎛ or less.

[0022] (7) The present invention provides a positive electrode active material precursor in which, in any one of (1) to (6) above, the core portion comprises a transition metal hydroxide represented by the following chemical formula 1.

[0023] [Chemical Formula 1]

[0024] Ni a1 Co b1 Mn c1 M 1d1 (OH)2

[0025] In the above chemical formula 1,

[0026] The above M 1 is one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y, and

[0027] 0.6≤a1<1.0, 0 <b1<0.4, 0<c1<0.4, 0≤d1≤0.1, a1+b1+c1+d1=1이다.

[0028] (8) The present invention provides a positive active material precursor in which, in any one of (1) to (7) above, the shell portion comprises a transition metal hydroxide represented by the following chemical formula 2.

[0029] [Chemical Formula 2]

[0030] Ni a2 Co b2 Mn c2 M 2 d2 (OH)2

[0031] In the above chemical formula 2,

[0032] The above M 2 is one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y, and

[0033] 0.6≤a2<1.0, 0 <b2<0.4, 0<c2<0.4, 0≤d2≤0.1, a2+b2+c2+d2=1이다.

[0034]

[0035] The positive active material precursor of the present invention satisfies the condition that the ratio of the primary particle size of the shell portion to the primary particle size of the core portion is 0.7 or more and 1.0 or less, thereby effectively suppressing the formation of pore bands inside the precursor, and accordingly, the density of the particles themselves can be increased to manufacture a lithium secondary battery having high energy density.

[0036]

[0037] Figure 1 is an SEM image of the core portion of the positive active material precursor of Example 1.

[0038] Figure 2 is an SEM image of the core portion of the positive active material precursor of Example 2.

[0039] Figure 3 is an SEM image of the core portion of the positive active material precursor of Comparative Example 1.

[0040] Figure 4 is an SEM image of the core portion of the positive active material precursor of Comparative Example 2.

[0041] Figure 5 is an SEM image of the shell portion of the positive active material precursor of Example 1.

[0042] Figure 6 is an SEM image of the shell portion of the positive active material precursor of Example 2.

[0043] Figure 7 is an SEM image of the shell portion of the positive active material precursor of Comparative Example 1.

[0044] Figure 8 is an SEM image of the shell portion of the positive active material precursor of Comparative Example 2.

[0045] Figure 9 is a cross-sectional SEM image of the positive active material precursor of Example 1.

[0046] Figure 10 is a cross-sectional SEM image of the positive active material precursor of Example 2.

[0047] Figure 11 is a cross-sectional SEM image of the positive active material precursor of Comparative Example 1.

[0048] Figure 12 is a cross-sectional SEM image of the positive active material precursor of Comparative Example 2.

[0049] Figure 13 is a segmentation image obtained by performing image analysis on the core portion of the positive active material precursor of Example 1.

[0050] Figure 14 is a segmentation image obtained by performing image analysis on the core portion of the positive active material precursor of Example 2.

[0051] Figure 15 is a segmentation image obtained by performing image analysis on the core portion of the positive active material precursor of Comparative Example 1.

[0052] Figure 16 is a segmentation image obtained by performing image analysis on the core portion of the positive active material precursor of Comparative Example 2.

[0053] Figure 17 is a segmentation image obtained by performing image analysis on the shell portion of the positive active material precursor of Example 1.

[0054] Figure 18 is a segmentation image obtained by performing image analysis on the shell portion of the positive active material precursor of Example 2.

[0055] Figure 19 is a segmentation image obtained by performing image analysis on the shell portion of the positive active material precursor of Comparative Example 1.

[0056] Figure 20 is a segmentation image obtained by performing image analysis on the shell portion of the positive active material precursor of Comparative Example 2.

[0057]

[0058] The present invention will be described in more detail below to aid in understanding. In this regard, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0059] The terms used in this specification are used merely to describe exemplary embodiments and are not intended to limit the invention. The singular expression includes the plural expression unless the context clearly indicates otherwise.

[0060] In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0061] In this specification, 'primary particle' refers to a minimum particle unit that is distinguished as a single mass when the cross-section of the positive active material is observed through a scanning electron microscope (SEM), and may consist of a single crystal grain or multiple crystal grains. In the present invention, the size of the primary particle may be a value calculated by calculating information for each particle distinguished in the cross-sectional SEM data of the positive active material precursor.

[0062] In the present invention, 'secondary particle' refers to a secondary structure formed by the aggregation of a plurality of primary particles. The average particle size of the secondary particle can be measured using a particle size analyzer (e.g., Microtrac s3500).

[0063] In this specification, 'D 50 ' refers to the particle size at the 50% point of the cumulative volume distribution according to particle size. The above D 50The particle size can be measured by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Malvern Mastersizer 3000), measuring the difference in diffraction patterns according to particle size as the particles pass through a laser beam to calculate the particle size distribution, and calculating the particle diameter at the point where the cumulative volume distribution according to particle size in the measuring device is 50%.

[0064]

[0065] positive electrode active material precursor

[0066] The present invention provides a positive electrode active material precursor comprising: a core portion comprising nickel, cobalt, and manganese, wherein the core portion comprises secondary particles aggregated from a plurality of primary particles; and a shell portion comprising nickel, cobalt, and manganese, which surrounds the surface of the core portion, wherein the ratio (b / a) of the primary particle size (b) of the shell portion to the primary particle size (a) of the core portion is 0.7 or more and 1.0 or less, and the primary particle size is calculated through the following formula 1.

[0067] [Equation 1]

[0068]

[0069] In Equation 1 above, the area of ​​the primary particle is the area obtained by approximating the primary particle as an ellipse from the segmentation image partitioned by primary particle unit, obtained by image processing of the SEM image (unit: μm). 2 ) and the diameter of the primary particle is the diameter of a circle having the same area as the area of ​​the primary particle (unit: μm).

[0070] The inventors confirmed that when the shape of the core and shell portions of a precursor is controlled such that the ratio of the primary particle size of the shell portion to the primary particle size of the core portion of the positive active material precursor is 0.7 or more and 1.0 or less, the formation of pore bands inside the precursor is suppressed and the quality of the precursor is improved, and thus completed the present invention.

[0071] Specifically, the ratio (b / a) of the primary particle size (b) of the shell portion to the primary particle size (a) of the core portion may be 0.7 or more, 0.72 or more, 0.74 or more, 0.76 or more, 0.78 or more, 0.8 or more, 0.82 or more, 0.84 or more, 0.86 or more, 0.88 or more, 0.9 or more, or 0.92 or more, and may be 0.95 or less, 0.96 or less, 0.97 or less, 0.98 or less, 0.99 or less, or 1.0 or less. When the b / a value satisfies the above range, the formation of pore bands inside the precursor can be suppressed, and accordingly, the density of the precursor particles themselves can be increased, thereby enabling the manufacture of a lithium secondary battery having high energy density.

[0072] Meanwhile, if the ratio (b / a) of the primary particle size (b) of the shell portion to the primary particle size (a) of the core portion is less than 0.7, pores are formed in the precursor and the particle density is lowered, and if it is greater than 1.0, pores are formed in the precursor and the particle density may be lowered.

[0073]

[0074] According to the present invention, the primary particle size of the core portion may be 0.1 μm or more and 0.25 μm or less. Specifically, the primary particle size of the core portion may be 0.1 μm or more, 0.11 μm or more, 0.12 μm or more, 0.13 μm or more, 0.14 μm or more, 0.15 μm or more, and may be 0.2 μm or less, 0.21 μm or less, 0.22 μm or less, 0.23 μm or less, 0.24 μm or less, and 0.25 μm or less.

[0075] According to the present invention, the primary particle size of the shell portion may be 0.1㎛ or more and 0.25㎛ or less. Specifically, the primary particle size of the shell portion may be 0.1㎛ or more, 0.11㎛ or more, 0.12㎛ or more, 0.13㎛ or more, 0.14㎛ or more, 0.15㎛ or more, and 0.19㎛ or less, 0.2㎛ or less, 0.21㎛ or less, 0.22㎛ or less, 0.23㎛ or less, 0.24㎛ or less, and 0.25㎛ or less.

[0076]

[0077] According to the present invention, the average particle size (D of the core part) 50 The size may be 3㎛ or larger and 6㎛ or smaller. Specifically, the average particle size of the core portion may be 3㎛ or larger, 3.1㎛ or larger, 3.2㎛ or larger, 3.3㎛ or larger, 3.4㎛ or larger, 3.5㎛ or larger, 3.6㎛ or larger, 3.7㎛ or larger, 3.8㎛ or larger, 3.9㎛ or larger, and may be 5.6㎛ or smaller, 5.7㎛ or smaller, 5.8㎛ or smaller, 5.9㎛ or smaller, or 6㎛ or smaller. When the average particle size of the core portion satisfies the above range, the particle strength may be improved.

[0078]

[0079] According to the present invention, the thickness of the shell portion may be 25% or more and 50% or less of the total particle size of the precursor (the particle size of the precursor particle including the core portion and the shell portion). Specifically, the thickness of the shell portion may be 25% or more, 26% or more, 27% or more, 28% or more, 29% or more, and 30% or more of the total particle size of the precursor, and may be 35% or less, 40% or less, 45% or less, and 50% or less. When the thickness of the shell portion satisfies the above range, the crystallinity of the particle can be secured.

[0080]

[0081] According to the present invention, the average particle size (D) of the positive electrode active material precursor 50The average particle size of the positive electrode active material precursor may be 10㎛ or more and 16㎛ or less. Specifically, the average particle size of the positive electrode active material precursor may be 10㎛ or more, 10.2㎛ or more, 10.4㎛ or more, 10.6㎛ or more, 10.8㎛ or more, 11㎛ or more, 11.2㎛ or more, 11.4㎛ or more, 11.6㎛ or more, and 14.4㎛ or less, 14.6㎛ or less, 14.8㎛ or less, 15㎛ or less, 15.2㎛ or less, 15.4㎛ or less, 15.6㎛ or less, 15.8㎛ or less, and 16㎛ or less. When the average particle size of the positive electrode active material precursor satisfies the above range, a lithium secondary battery having excellent capacity characteristics and output characteristics can be manufactured.

[0082]

[0083] According to the present invention, the core portion may comprise a transition metal hydroxide represented by the following chemical formula 1.

[0084] [Chemical Formula 1]

[0085] Ni a1 Co b1 Mn c1 M 1 d1 (OH)2

[0086] In the above chemical formula 1,

[0087] The above M 1 is one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y, and

[0088] 0.6≤a1<1.0, 0 <b1<0.4, 0<c1<0.4, 0≤d1≤0.1, a1+b1+c1+d1=1이다.

[0089] In the above chemical formula 1, a1, b1, and c1 may each be the mole fractions for nickel (Ni), cobalt (Co), and manganese (Mn) among the transition metals.

[0090] The above M 1The doping element may be one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y.

[0091] The above a1 is a mole fraction of nickel (Ni) among transition metals, which may be 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, 0.9 or more, 0.95 or more, and may be less than 1.0 or 0.98 or less.

[0092] The above b1 is a mole fraction of cobalt (Co) among transition metals, which may be greater than 0, 0.0005 or more, 0.001 or more, 0.002 or more, 0.003 or more, 0.004 or more, 0.005 or more, less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less.

[0093] The above c1 is a mole fraction for manganese (Mn) among transition metals, and may be greater than 0, 0.005 or more, 0.01 or more, 0.015 or more, 0.02 or more, less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.04 or less.

[0094] The above d1 is M among transition metals. 1 As a mole fraction for, it may be 0 or more, 0.005 or more, 0.01 or more, and 0.03 or less, 0.05 or less, 0.1 or less.

[0095]

[0096] According to the present invention, the shell portion may comprise a transition metal hydroxide represented by the following chemical formula 2.

[0097] [Chemical Formula 2]

[0098] Ni a2 Co b2 Mnc2 M 2 d2 (OH)2

[0099] In the above chemical formula 2,

[0100] The above M 2 is one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y, and

[0101] 0.6≤a2<1.0, 0 <b2<0.4, 0<c2<0.4, 0≤d2≤0.1, a2+b2+c2+d2=1이다.

[0102] In the above chemical formula 2, a2, b2, and c2 may each be mole fractions for nickel (Ni), cobalt (Co), and manganese (Mn) among the transition metals.

[0103] The above M 2 The doping element may be one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S and Y.

[0104] The above a2 is a mole fraction of nickel (Ni) among transition metals, which may be 0.6 or more, 0.65 or more, 0.7 or more, 0.75 or more, 0.8 or more, 0.85 or more, 0.9 or more, 0.95 or more, and may be less than 1.0 or 0.98 or less.

[0105] The above b2 is a mole fraction of cobalt (Co) among transition metals, which may be greater than 0, 0.0005 or more, 0.001 or more, 0.002 or more, 0.003 or more, 0.004 or more, 0.005 or more, less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less.

[0106] The above c2 is a mole fraction for manganese (Mn) among transition metals, and may be greater than 0, 0.005 or more, 0.01 or more, 0.015 or more, 0.02 or more, less than 0.4, 0.3 or less, 0.2 or less, 0.1 or less, 0.05 or less, 0.04 or less.

[0107] The above d2 is M among transition metals. 2 As a mole fraction for, it may be 0 or more, 0.005 or more, 0.01 or more, and 0.03 or less, 0.05 or less, 0.1 or less.

[0108]

[0109] Method for manufacturing a positive electrode active material precursor

[0110] The positive active material precursor according to the present invention may be manufactured by the following manufacturing method, but is not limited thereto.

[0111] The above method for manufacturing a positive electrode active material precursor may include (A) a step of manufacturing a core portion of a positive electrode active material precursor and (B) a step of manufacturing a shell portion of a positive electrode active material precursor. Each step is described in detail below.

[0112]

[0113] (A) A step of manufacturing the core portion of the positive active material precursor

[0114] The core portion of the above-mentioned positive active material precursor can be prepared by co-precipitating a transition metal-containing solution containing nickel, cobalt, and manganese, a basic aqueous solution, and an ammonium cation complex-forming agent. Specifically, the core portion of the positive active material precursor can be prepared by introducing a reaction solution containing the transition metal-containing solution, the basic aqueous solution, and the ammonium cation complex-forming agent into a reactor and performing a co-precipitation reaction.

[0115] At this time, by controlling reaction conditions such as the pH inside the reactor, the input rate of the reaction solution, and the reaction time, the primary particle size of the core portion of the cathode active material precursor, and the D portion of the core 50, precursor's D 50 You can adjust the back.

[0116]

[0117] The above transition metal-containing solution includes nickel, cobalt, and manganese. The above transition metal-containing solution may include acetates, nitrates, sulfates, halides, sulfides, hydroxides, oxides, or oxyhydroxides of the metals, and is not particularly limited as long as it is soluble in water.

[0118] The above basic aqueous solution may include one or more selected from alkali metal hydrates, alkali metal hydroxides, alkaline earth metal hydrates, and alkaline earth metal hydroxides. For example, the above basic aqueous solution may include NaOH, KOH, or Ca(OH)2, and as a solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water may be used. The basic aqueous solution may be added in an amount such that the pH of the reaction solution becomes within a desired range.

[0119] The above ammonium cation complex-forming agent may include one or more selected from NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3. As a solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water may be used. In addition, the ammonium cation complex-forming agent may be added in an amount such that the concentration of ammonium cations reaches a desired range.

[0120]

[0121] According to the present invention, the pH in the reactor during the manufacture of the core part may be in a range of 11 or higher and 12 or lower, specifically 11 or higher, 11.1 or higher, 11.2 or higher, and 11.6 or lower, 11.7 or lower, 11.8 or lower, 11.9 or lower, and 12 or lower. When the pH in the reactor during the manufacture of the core part satisfies the above range, the size of the primary particles can be controlled to a target size and the formation of pore bands in the precursor can be effectively suppressed. When the pH in the reactor during the manufacture of the core part is higher than the above range, the primary particles can be formed thickly, and in this case, pore bands in the precursor can be formed.

[0122] According to the present invention, in the step of manufacturing a core part, the ratio of the input rate (mol / hr) of the ammonium cation complex forming agent to the input rate (mol / hr) of the transition metal-containing solution may be 0.10 or more and 0.50 or less. Specifically, the ratio may be 0.10 or more, 0.15 or more, 0.20 or more, 0.25 or more, and 0.35 or less, 0.40 or less, 0.45 or less, and 0.50 or less. In addition, the ratio of the input rate (mol / hr) of the basic aqueous solution to the input rate (mol / hr) of the transition metal-containing solution may be 1.1 or more and 2.5 or less; specifically, the ratio may be 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, 1.5 or more, or 1.6 or more, and may be 2.1 or less, 2.2 or less, 2.3 or less, 2.4 or less, or 2.5 or less. When the input rates (mol / hr) of the transition metal-containing solution, the ammonium cation complex forming agent, and the basic aqueous solution satisfy the above ranges, D of the core part 50 The core can be manufactured so that the primary particle size of the core satisfies the target range.

[0123] According to the present invention, the reaction time in the step of manufacturing the core part may be 32 hours or more and 45 hours or less. Specifically, the reaction time may be 32 hours or more, 33 hours or more, 34 hours or more, 35 hours or more, and 36 hours or more, and may be 37 hours or less, 38 hours or less, 39 hours or less, 40 hours or less, 41 hours or less, 42 hours or less, 43 hours or less, 44 hours or less, and 45 hours or less. When the reaction time satisfies the above range, D of the core part 50 The core can be manufactured so that the primary particle size of the core satisfies the target range.

[0124]

[0125] The core portion of the positive active material precursor according to the present invention can be manufactured through the step of manufacturing the core portion of (A) the positive active material precursor by controlling the reaction conditions as above.

[0126]

[0127] (B) Step of manufacturing the shell portion of the positive active material precursor

[0128] The shell portion of the above-described positive active material precursor can be prepared by introducing the core portion particles of the positive active material precursor prepared as described above into a reactor, and further introducing a transition metal-containing solution containing nickel, cobalt, and manganese, a basic aqueous solution, and an ammonium cation complex-forming agent, and carrying out a co-precipitation reaction. Specifically, the shell portion of the positive active material precursor can be prepared by introducing a reaction solution containing the core portion particles, the transition metal-containing solution, the basic aqueous solution, and the ammonium cation complex-forming agent into a reactor and performing a co-precipitation reaction.

[0129] At this time, by controlling reaction conditions such as the pH inside the reactor, the input rate of the reaction solution, and the reaction time, the primary particle size of the shell portion of the cathode active material precursor, the thickness of the shell portion, and the D of the precursor are controlled. 50 You can adjust the back.

[0130]

[0131] The above transition metal-containing solution, basic aqueous solution, and ammonium cation complex-forming agent may be within the aforementioned range.

[0132]

[0133] According to the present invention, the pH in the reactor during the manufacture of the shell part may be in a range of 11 or more and less than 12, specifically 11 or more, 11.1 or more, 11.2 or more, 11.3 or more, 11.4 or more, and 11.6 or less, 11.7 or less, 11.8 or less, 11.9 or less, and less than 12.

[0134] According to the present invention, by controlling the pH in the reactor during the production of the core part and the pH in the reactor during the production of the shell part to be similar, that is, by controlling the chemical conditions during the production of the core part and the chemical conditions during the production of the shell part to be similar, a precursor can be produced such that the ratio of the primary particle size of the shell part to the primary particle size of the core part satisfies a range of 0.7 or more and 1.0 or less.

[0135] When the chemical conditions during the manufacturing of the core and the shell are similar, the primary particles of the shell can be formed following the primary particles formed in the core, thereby forming primary particles of similar size, and consequently, pores inside the precursor can be suppressed. When the chemical conditions during the manufacturing of the core and the shell are different and the chemical equilibrium is disrupted, the crystals do not grow along the primary particles formed in the core; instead, new fine particles are formed and then adhere to the core, causing the primary particles of the core and the shell to be formed in different shapes, which can lead to the formation of more pores inside the precursor.

[0136] According to the present invention, in the step of manufacturing the shell part, the transition metal-containing solution and the ammonium cation complex-forming agent may maintain the same input rate during the reaction, or the input rate may be different during the reaction.

[0137] According to the present invention, in the step of manufacturing a shell part, the ratio of the input rate (mol / hr) of the ammonium cation complex forming agent to the input rate (mol / hr) of the transition metal-containing solution may be 0.10 or more and 1.00 or less. Specifically, the ratio may be 0.10 or more, 0.15 or more, 0.20 or more, 0.25 or more, 0.30 or more, and 0.50 or less, 0.60 or less, 0.70 or less, 0.80 or less, 0.90 or less, and 1.00 or less. The ratio of the input rate of the ammonium cation complex-forming agent to the input rate of the transition metal-containing solution refers to the ratio of the input rate of the initial ammonium cation complex-forming agent to the input rate of the initial transition metal-containing solution, or the ratio of the input rate of the later ammonium cation complex-forming agent to the input rate of the later transition metal-containing solution, in cases where the input rates of the transition metal-containing solution and the ammonium cation complex-forming agent change during the reaction.

[0138] In addition, the ratio of the input rate (mol / hr) of the basic aqueous solution to the input rate (mol / hr) of the transition metal-containing solution may be 1.1 or higher and 3.2 or lower. Specifically, the ratio may be 1.1 or higher, 1.2 or higher, 1.3 or higher, 1.4 or higher, 1.5 or higher, 1.6 or higher, and 2.8 or lower, 2.9 or lower, 3.0 or lower, 3.1 or lower, or 3.2 or lower. The ratio of the input rate of the basic aqueous solution to the input rate of the transition metal-containing solution refers to the ratio of the input rate of the basic aqueous solution to the initial input rate of the transition metal-containing solution when the input rates of the transition metal-containing solution and the ammonium cation complex forming agent change during the reaction.

[0139] When the input rates of the above transition metal-containing solution, ammonium cation complex-forming agent, and basic aqueous solution satisfy the above range, the core part can be manufactured such that the thickness of the shell part and the primary particle size of the shell part satisfy the target range.

[0140] According to the present invention, the reaction time in the step of manufacturing the shell part may be 35 hours or more and 52 hours or less. Specifically, the reaction time may be 35 hours or more, 36 hours or more, 37 hours or more, 38 hours or more, 39 hours or more, 40 hours or more, and 41 hours or more, and may be 47 hours or less, 48 ​​hours or less, 49 hours or less, 50 hours or less, 51 hours or less, and 52 hours or less. When the reaction time satisfies the above range, the shell part can be manufactured such that the thickness of the shell part and the primary particle size of the shell part satisfy the target range.

[0141]

[0142] The shell portion of the positive active material precursor according to the present invention can be manufactured through the step of manufacturing the shell portion of the (B) positive active material precursor by controlling the reaction conditions as above.

[0143]

[0144] Examples

[0145] The present invention will be explained in more detail below through examples. However, the following examples are intended to illustrate the present invention and do not limit the scope of the present invention.

[0146]

[0147] Example 1

[0148] A transition metal-containing solution with a concentration of 2.4 M was prepared by mixing NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O in deionized water in amounts such that the molar ratio of Ni:Co:Mn was 97.5:0.5:2.

[0149] Aqueous NaOH and NH4OH solutions were added to an 80L concentrated co-precipitation reactor to concentrations of 0.02M and 0.3M, respectively, and 28L of water was added. Then, nitrogen gas was purged into the reactor at a rate of 20L / min to remove dissolved oxygen. The stirring speed was maintained at 600rpm, the reaction temperature at 50-60℃, and the pH inside the reactor at 12.2-12.6.

[0150] Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 18.4 mol / hr and 5.5 mol / hr, respectively, while an aqueous NaOH solution was introduced at a controlled rate of 30–37 mol / hr to maintain the pH at 11.2–11.4. The reactor became full after 2.5 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction was carried out for a total of 36.5 hours, and the average particle size (D 50 ) is 5.61㎛, and Ni 0.975 Co 0.005 Mn 0.02 Core particles having a (OH)2 composition were prepared. The prepared core particles were separated from the waste liquid and stored under conditions where they did not come into contact with the outside air.

[0151] Next, the core particles were introduced into the reactor, and an aqueous NaOH solution was added to a concentration of 7.93 M to achieve a pH of 11.5. Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 18.4 mol / hr and 5.5 mol / hr, respectively, while the aqueous NaOH solution was added at a rate of 30-37 mol / hr to maintain the pH at 11.4-11.6. The reactor became full after 3.5 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction proceeded for a total of 41.5 hours, and Ni on the surface of the core particles 0.975 Co 0.005 Mn 0.02 A shell portion (thickness: 4.26 μm) having a (OH)2 composition was formed. The average particle size (D) of the precursor thus prepared 50The particle size was 14.13㎛, and the manufactured precursor particles were separated from the waste liquid, washed with water at 40-50℃, dried in an oven at 120℃ for 15 hours, and sieved to produce a positive electrode active material precursor.

[0152]

[0153] Example 2

[0154] A transition metal-containing solution with a concentration of 2.4 M was prepared by mixing NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O in deionized water in amounts such that the molar ratio of Ni:Co:Mn was 97.5:0.5:2.

[0155] Aqueous NaOH and NH4OH solutions were added to an 80L concentrated co-precipitation reactor to concentrations of 0.02M and 0.3M, respectively, and 28L of water was added. Then, nitrogen gas was purged into the reactor at a rate of 20L / min to remove dissolved oxygen. The stirring speed was maintained at 600rpm, the reaction temperature at 50-60℃, and the pH inside the reactor at 12.2-12.6.

[0156] Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 18.4 mol / hr and 5.5 mol / hr, respectively, while an aqueous NaOH solution was introduced at a controlled rate of 30–37 mol / hr to maintain the pH at 11.4–11.6. The reactor became full after 2.5 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction was carried out for a total of 36.5 hours, and the average particle size (D 50 ) is 3.92㎛, and Ni 0.975 Co 0.005 Mn 0.02 Core particles having a (OH)2 composition were prepared. The prepared core particles were separated from the waste liquid and stored under conditions where they did not come into contact with the outside air.

[0157] Next, the core particles were introduced into the reactor, and an aqueous NaOH solution was added to a concentration of 7.93 M to achieve a pH of 11.5. Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 13.7 mol / hr and 4.1 mol / hr, respectively, while the NaOH solution was introduced at a rate of 27-37 mol / hr to maintain the pH at 11.4-11.6. After 8 hours, the flow rates of the transition metal-containing solution and the aqueous NH4OH solution were changed to 17.4 mol / hr and 8.7 mol / hr, respectively. The reactor became full after 2 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction proceeded for a total of 46.4 hours, and Ni on the surface of the core particles 0.975 Co 0.005 Mn 0.02 A shell portion (thickness: 3.82 μm) having a (OH)2 composition was formed. The average particle size (D) of the precursor thus prepared 50 The particle size was 11.56 μm, and the manufactured precursor particles were separated from the waste liquid, washed with water at 40-50°C, dried in an oven at 120°C for 15 hours, and sieved to produce a positive electrode active material precursor.

[0158]

[0159] Comparative Example 1

[0160] A transition metal-containing solution with a concentration of 2.4 M was prepared by mixing NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O in deionized water in amounts such that the molar ratio of Ni:Co:Mn was 96:2:2.

[0161] Aqueous NaOH and NH4OH solutions were added to a 250L concentrated co-precipitation reactor to concentrations of 0.035M and 0.3M, respectively, and 90L of water was added. Then, nitrogen gas was purged into the reactor at a rate of 20L / min to remove dissolved oxygen. The stirring speed was maintained at 600rpm, the reaction temperature at 50-60℃, and the pH inside the reactor at 12.2-12.6.

[0162] Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 18.4 mol / hr and 5.5 mol / hr, respectively, while an aqueous NaOH solution was introduced at a controlled rate of 30–37 mol / hr to maintain the pH at 12.3–12.5. The reactor became full after 2.5 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction was carried out for a total of 30 hours, and the average particle size (D 50 ) is 3.89㎛, and Ni 0.96 Co 0.02 Mn 0.02 Core particles having a (OH)2 composition were prepared. The prepared core particles were separated from the waste liquid and stored under conditions where they did not come into contact with the outside air.

[0163] Next, the core particles were introduced into the reactor, and an aqueous NaOH solution was added to a concentration of 7.93 M to achieve a pH of 11.5. Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 42.8 mol / hr and 12.8 mol / hr, respectively, while the NaOH solution was introduced at a rate of 85-101 mol / hr to maintain the pH at 11.4-11.8. After 8 hours, the flow rates of the transition metal-containing solution and the aqueous NH4OH solution were changed to 50.2 mol / hr and 25.1 mol / hr, respectively. The reactor became full after 4 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction proceeded for a total of 47 hours, and Ni on the surface of the core particles 0.96 Co 0.02 Mn 0.02 A shell portion (thickness: 3.86 μm) having a (OH)2 composition was formed. The average particle size (D) of the precursor thus prepared 50 The particle size was 11.61 μm, and the manufactured precursor particles were separated from the waste liquid, washed with water at 40-50°C, dried in an oven at 120°C for 15 hours, and sieved to produce a positive electrode active material precursor.

[0164]

[0165] Comparative Example 2

[0166] A transition metal-containing solution with a concentration of 2.4 M was prepared by mixing NiSO4·6H2O, CoSO4·7H2O, and MnSO4·H2O in amounts such that the molar ratio of Ni:Co:Mn is 89:4:7, and Zr(SO4)2·4H2O in an amount of 3000 ppm relative to the total weight of the transition metal raw materials (total weight of Ni, Co, Mn, Zr raw materials) in deionized water.

[0167] Aqueous NaOH and NH4OH solutions were added to a 10L concentrated co-precipitation reactor to concentrations of 0.05M and 0.2M, respectively, and 4L of water was added. Then, nitrogen gas was purged into the reactor at a rate of 10L / min to remove dissolved oxygen. The stirring speed was maintained at 900rpm, the reaction temperature at 50-60℃, and the pH inside the reactor at 12.2-12.5.

[0168] Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 2.29 mol / hr and 0.69 mol / hr, respectively, while an aqueous NaOH solution was introduced at a controlled rate of 4.5–5.0 mol / hr to maintain the pH at 11.8–12.0. The reactor became full after 2.5 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction proceeded for a total of 29.5 hours, and the average particle size (D 50 ) is 3.28㎛, and Ni 0.887 Co 0.04 Mn 0.07 Zr 0.003 Core particles having a (OH)2 composition were prepared. The prepared core particles were separated from the waste liquid and stored under conditions where they did not come into contact with the outside air.

[0169] Next, the core particles were introduced into the reactor, and an aqueous NaOH solution was added to a concentration of 7.93 M to achieve a pH of 12.0–12.1. Subsequently, a transition metal-containing solution and an aqueous NH4OH solution were introduced into the reactor at rates of 2.15 mol / hr and 1.08 mol / hr, respectively, while the aqueous NaOH solution was added at a rate of 4.0–4.5 mol / hr to maintain the pH at 12.0–12.2. The reactor became full after 2.5 hours, and only the reaction waste liquid was continuously discharged to the outside of the reactor through an internal filtration device. The reaction proceeded for a total of 70 hours, and Ni on the surface of the core particles 0.887 Co 0.04 Mn 0.07 Zr 0.003 A shell portion (thickness: 3.39 μm) having a (OH)2 composition was formed. The average particle size (D) of the precursor thus prepared 50 The particle size was 10.06 μm, and the manufactured precursor particles were separated from the waste liquid, washed with water at 40-50°C, dried in an oven at 120°C for 15 hours, and sieved to produce a positive electrode active material precursor.

[0170]

[0171] Experimental Example

[0172] Experimental Example 1: SEM Image Measurement

[0173] Scanning electron microscope (Hitachi SU-3500) was used to take SEM images of the core and shell portions of the cathode active material precursors of Examples 1 and 2 and Comparative Examples 1 and 2, and these images are shown in FIGS. 1 to 4 (core portion) and FIGS. 5 to 8 (shell portion), respectively.

[0174] In addition, cross-sectional SEM images of the cathode active material precursors of Examples 1 and 2 and Comparative Examples 1 and 2 were taken using a scanning electron microscope (Hitachi S4800) and are shown in FIGS. 9 to 12, respectively.

[0175]

[0176] Experimental Example 2: Measurement of Primary Particle Size

[0177] Image analysis (DX analysis) was performed on the SEM images of the cathode active material precursors of Examples 1 and 2 and Comparative Examples 1 and 2 in the following manner to measure the size of the primary particles in the core and the primary particles in the shell.

[0178] For image analysis, each captured SEM image was input into an artificial intelligence model based on U-NET to generate boundary images. Subsequently, boundaries were removed from the SEM images based on the boundary images to generate demarcation images, and multiple objects (primary particles) included in the demarcation images were identified. Based on the identified multiple objects, the multiple objects included in the SEM images were segmented to obtain segmentation images, and based on the objects included in the segmentation images, the multiple primary particles were approximated as ellipses to determine their area (unit: μm). 2 ...was calculated. Approximating with an ellipse involves measuring the major and minor axes of the primary particle and assuming an ellipse with the same major and minor axes. Then, assuming a circle with the same area, the diameter (unit: μm) was calculated, and the size of the primary particle was calculated using Equation 1 below, which is shown in Table 1 below.

[0179] [Equation 1]

[0180]

[0181]

[0182] Each segmentation image analyzed was shown as follows: the segmentation images of the core particles are shown in FIGS. 13 to 16, and the segmentation images of the shell (i.e., the positive active material precursor) are shown in FIGS. 17 to 20.

[0183]

[0184] Primary particle size of the core part (a) (㎛) Primary particle size of the shell part (b) (㎛) Ratio of the primary particle size of the shell part (b) to the primary particle size of the core part (a) (b / a) Example 10.16 4 10.15 3 6 0.936 Example 20.19 79 0.18 7 10.945 Comparative Example 10.32 47 0.19 15 0.590 Comparative Example 20.27 65 0.41 59 1.504

[0185]

[0186] Referring to Table 1 and Figures 7 to 9 above, it can be confirmed that the ratio (b / a) of the primary particle size (b) of the shell portion to the primary particle size (a) of the core portion is 0.7 or more and 1.0 or less, thereby effectively suppressing the formation of pore bands within the precursor particles.

Claims

1. It is a secondary particle formed by the aggregation of multiple primary particles, and A core portion comprising nickel, cobalt, and manganese; and a shell portion surrounding the surface of the core portion and comprising nickel, cobalt, and manganese, wherein The ratio (b / a) of the primary particle size (b) of the shell portion to the primary particle size (a) of the core portion is 0.7 or more and 1.0 or less, and A positive active material precursor whose primary particle size is calculated through the following Equation 1: [Equation 1] In the above Equation 1, The area of ​​the primary particle is the area calculated by approximating the primary particle as an ellipse from the segmentation image partitioned by primary particle unit, obtained by processing the SEM image (Unit: μm). 2 ) and, The diameter of the primary particle is the diameter of a circle having the same area as the area of ​​the primary particle (unit: μm).

2. In Claim 1, A positive active material precursor having a primary particle size of 0.1㎛ or more and 0.25㎛ or less of the core portion.

3. In Claim 1, A positive active material precursor having a primary particle size of 0.1㎛ or more and 0.25㎛ or less of the shell portion.

4. In Claim 1, Average particle size (D of the above core part) 50 ) is a positive electrode active material precursor having a size of 3㎛ or more and 6㎛ or less.

5. In Claim 1, A positive active material precursor in which the thickness of the shell portion is 25% or more and 50% or less of the total particle size of the precursor.

6. In Claim 1, Average particle size (D) of the above positive active material precursor 50 ) is a positive electrode active material precursor having a size of 10㎛ or more and 16㎛ or less.

7. In Claim 1, The above-mentioned core portion is an anode active material precursor comprising a transition metal hydroxide represented by the following chemical formula 1: [Chemical Formula 1] Ni a1 What b1 Mn c1 M 1 d1 (OH)2 In the above chemical formula 1, The above M 1 is one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y, and 0.6≤a1<1.0, 0 <b1<0.4, 0<c1<0.4, 0≤d1≤0.1, a1+b1+c1+d1=1이다.

8. In Claim 1, The above-mentioned shell portion is an anode active material precursor comprising a transition metal hydroxide represented by the following chemical formula 2: [Chemical Formula 2] Ni a2 What b2 Mn c2 M 2 d2 (OH)2 In the above chemical formula 2, The above M 2 is one or more selected from the group consisting of Al, Zr, B, Ce, V, Fe, Zn, Si, Ga, Sn, Hf, W, Mo, Cr, Nb, Mg, Hf, Ta, La, Ti, Sr, Ba, F, P, S, and Y, and 0.6≤a2<1.0, 0 <b2<0.4, 0<c2<0.4, 0≤d2≤0.1, a2+b2+c2+d2=1이다.

Images