Method for producing positive electrode active material precursor and positive electrode active material precursor

Abstract

The present invention relates to: a method for producing a positive electrode active material precursor; and a positive electrode active material precursor. The method comprises the steps of: (A) mixing a composite transition metal-containing solution, an aqueous basic solution, and an ammonium cation complex forming agent to prepare a precipitate through a co-precipitation reaction; (B) separating and washing the precipitate to obtain a preliminary composite transition metal hydroxide; and (C) immersing the preliminary composite transition metal hydroxide in an aqueous solution having a pH of 12-14 to produce a surface-treated composite transition metal hydroxide, wherein the step (C) is performed for 7-48 hours.

Description

Method for manufacturing a cathode active material precursor and a cathode active material precursor

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0128098, filed September 25, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a method for manufacturing a positive electrode active material precursor and a positive electrode active material precursor.

[0005]

[0006] Lithium secondary batteries are composed of four major components: a cathode, an anode, a separator, and an electrolyte. Among these, the cathode active material contained in the cathode plays a significant role in determining the battery's capacity, output, and lifespan. For lithium secondary batteries to achieve high energy density, output, and lifespan, improving the performance of the cathode active material is essential. Consequently, extensive research has been conducted recently to develop high-performance cathode active materials.

[0007] Lithium-transition metal composite metal oxides are used as cathode active materials in lithium secondary batteries. Among these, lithium-cobalt composite metal oxides such as LiCoO2, which exhibit high operating voltage and excellent capacity characteristics, are primarily used. However, LiCoO2 has very poor thermal properties due to crystal structure instability caused by delithiation. Furthermore, LiCoO2 is expensive, limiting its mass use as a power source in fields such as electric vehicles.

[0008] As a material to replace the above LiCoO2, lithium manganese composite metal oxides (such as LiMnO2 or LiMn2O4), lithium iron phosphate compounds (such as LiFePO4), or lithium nickel composite metal oxides (such as LiNiO2) have been developed. Among these, research and development on lithium nickel composite metal oxides, which have a high reversible capacity of about 200 mAh / g and make it easy to implement large-capacity batteries, is being actively studied. However, LiNiO2 has inferior thermal stability compared to LiCoO2, and there was a problem that the positive electrode active material itself decomposed when an internal short circuit occurred due to external pressure in a charged state, causing the battery to rupture and catch fire. Accordingly, as a method to improve the low thermal stability while maintaining the excellent reversible capacity of LiNiO2, a lithium nickel cobalt metal oxide in which some of the Ni was replaced with Co and Mn or Al was developed.

[0009] However, the lithium nickel cobalt metal oxide had a problem of low capacity. In order to increase the capacity of the lithium nickel cobalt metal oxide, methods of increasing the nickel content or increasing the packing density per unit volume of the positive electrode active material were studied.

[0010] In the past, in order to manufacture a positive electrode active material having a high packing density per unit volume, a method was used in which a small-diameter precursor and a large-diameter precursor were manufactured by differentiating the reaction times, and then the manufactured precursors were mixed and fired to manufacture a bimodal positive electrode active material, or the manufactured precursors were each fired and mixed to manufacture a bimodal positive electrode active material.

[0011] However, in this case, when manufacturing a large-diameter precursor, there was a problem that particle cracks occurred, which deteriorated the performance of the positive electrode active material, positive electrode, and secondary battery manufactured from it.

[0012] Therefore, it is necessary to secure a technology to improve particle cracks of the above-mentioned large-diameter precursor.

[0013]

[0014] [Prior Art Literature]

[0015] [Patent Document]

[0016] (Patent Document 1) Korean Patent Publication No. 10-2018-0064295

[0017]

[0018] The present invention is intended to solve the above problems, and provides a method for manufacturing a positive electrode active material precursor capable of reducing the ratio of particles having cracks among all composite transition metal hydroxide particles, and a positive electrode active material precursor having a low ratio of particles having cracks.

[0019]

[0020] (1) The present invention provides a method for producing a positive electrode active material precursor, comprising the steps of: (A) mixing a complex transition metal-containing solution, a basic aqueous solution, and an ammonium cation complex forming agent to produce a precipitate through a coprecipitation reaction; (B) separating and washing the precipitate to obtain a preliminary complex transition metal hydroxide; and (C) immersing the preliminary complex transition metal hydroxide in an aqueous solution having a pH of 12 to 14 to produce a surface-treated complex transition metal hydroxide; wherein step (C) is performed for 7 to 48 hours.

[0021] (2) The present invention provides a method for producing a positive electrode active material precursor in the above (1), wherein the preliminary complex transition metal hydroxide has a composition represented by the following chemical formula 1.

[0022] [Chemical Formula 1]

[0023] Ni a Co b Mn c M 1 d (OH)2

[0024] In the above chemical formula 1, M 1is at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr, and 0 <a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤0.1, a+b+c+d=1이다.

[0025] (3) The present invention provides a method for manufacturing a positive electrode active material precursor, wherein in the above (1) or (2), a is 0.55 to 0.95.

[0026] (4) The present invention provides a method for producing a positive electrode active material precursor, wherein in any one of the above (1) to (3), b is 0.04 to 0.2.

[0027] (5) The present invention provides a method for producing a positive electrode active material precursor, wherein in any one of the above (1) to (4), c is 0.04 to 0.3.

[0028] (6) In any one of the above (1) to (5), the preliminary complex transition metal hydroxide has an average particle diameter (D') 50 ) provides a method for manufacturing a positive electrode active material precursor having a diameter of 7㎛ to 20㎛.

[0029] (7) The present invention provides a method for producing a positive electrode active material precursor, wherein the preliminary composite transition metal hydroxide is in the form of secondary particles in which primary particles are aggregated, and the primary particles have an average aspect ratio of 1.5 to 1.9, in any one of the above (1) to (6).

[0030] (8) The present invention provides a method for producing a positive electrode active material precursor, wherein the ratio of the number of particles having cracks among the total particles of the preliminary complex transition metal hydroxide is 20% to 50%, in any one of the above (1) to (7).

[0031] (9) The present invention provides a method for producing a positive electrode active material precursor, wherein the pH is 12.9 to 13.5 in any one of the above (1) to (8).

[0032] (10) The present invention provides a method for producing a positive electrode active material precursor, wherein step (C) is performed at a temperature of 20°C to 80°C in any one of the above (1) to (9).

[0033] (11) The present invention provides a method for producing a positive electrode active material precursor, wherein the amount of the preliminary complex transition metal hydroxide supported in any one of the above (1) to (10) is 20 to 120 parts by weight with respect to 100 parts by weight of the aqueous solution.

[0034] (12) The present invention provides a method for producing a positive electrode active material precursor, wherein the composite transition metal hydroxide has a ratio of particles having cracks among all particles of the composite transition metal hydroxide of 10% or less in any one of the above (1) to (11).

[0035] (13) The present invention provides a positive electrode active material precursor comprising a composite transition metal hydroxide having a composition represented by the following chemical formula 2, wherein the composite transition metal hydroxide is in the form of secondary particles in which primary particles are aggregated, the primary particles have an average aspect ratio of 1.8 to 2.2, and the composite transition metal hydroxide has a ratio of particles having cracks among all particles of the composite transition metal hydroxide of 10% or less.

[0036] [Chemical Formula 2]

[0037] Ni p Co q Mn r M 2 s (OH)2

[0038] In the above chemical formula 2, M 2is a doping element, 0 <p≤1, 0≤q≤1, 0≤r≤1, 0≤s≤0.1, p+q+r+s=1이다.

[0039] (14) The present invention provides a positive electrode active material precursor according to (13), wherein p is 0.55 to 0.95.

[0040] (15) The present invention provides a positive electrode active material precursor according to (13) or (14), wherein q is 0.04 to 0.2.

[0041] (16) The present invention provides a positive electrode active material precursor according to any one of the above (13) to (15), wherein r is 0.04 to 0.3.

[0042] (17) The present invention provides a positive electrode active material precursor in any one of the above (13) to (16), wherein the composite transition metal hydroxide has a ratio of particles having cracks among all particles of the composite transition metal hydroxide of 5% or less.

[0043] (18) The present invention is characterized in that the composite transition metal hydroxide has an average particle diameter (D) in any one of the above (13) to (17). 50 ) provides a positive electrode active material precursor having a diameter of 7㎛ to 20㎛.

[0044]

[0045] The method for manufacturing a positive electrode active material precursor according to the present invention can effectively manufacture a positive electrode active material precursor having a low percentage of particles with cracks by surface-treating a preliminary complex transition metal hydroxide by immersing it in a strong alkaline aqueous solution for a specific period of time.

[0046]

[0047] Figure 1 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Comparative Example 1.

[0048] Figure 2 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Example 1.

[0049] Figure 3 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Comparative Example 1.

[0050] Figure 4 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Example 1.

[0051] Figure 5 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Comparative Example 3.

[0052] Figure 6 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Example 6.

[0053] Figure 7 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Comparative Example 3.

[0054] Figure 8 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Example 5.

[0055] Figure 9 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Example 6.

[0056] Figure 10 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 1.

[0057] Figure 11 is a segmentation image of the positive electrode active material precursor manufactured in Example 1.

[0058] Figure 12 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 3.

[0059] Figure 13 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 4.

[0060] Figure 14 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 5.

[0061] Figure 15 is a segmentation image of the positive electrode active material precursor manufactured in Example 5.

[0062] Figure 16 is a segmentation image of the positive electrode active material precursor manufactured in Example 6.

[0063]

[0064] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0065] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical spirit of the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best possible manner.

[0066] In this specification, it should be understood that terms such as “include,” “have,” or “have” are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0067] In this specification, a 'crack' may refer to an area where a particle surface is broken (split), which is distinguished from a particle boundary having a linear shape of a certain size or larger through boundary information learning in an image observed with a scanning electron microscope (SEM) at 0.5K magnification. Alternatively, a 'crack' may refer to an area that appears black or a area that appears darker than an adjacent area in an image observed with a scanning electron microscope (SEM) at 0.5K magnification. The area that appears dark is determined by the contrast difference with the surrounding area, and only an area that is not a particle boundary having a linear shape of a certain size or larger is determined to be a crack. On the other hand, if a crack does not exist, it may appear white or a color lighter than a crack in an adjacent area. The presence or absence of the 'crack' can be determined by visually observing an SEM image, and a relatively darker area compared to black or an adjacent area is determined to be a crack, and a relatively lighter area compared to white or an adjacent area is determined to be a crack free.

[0068] In this specification, 'particle' is a concept including any one or all of a single particle, a primary particle, and a secondary particle.

[0069] In this specification, 'primary particle' means the smallest particle unit recognized when observing a positive electrode active material precursor using a scanning electron microscope (SEM), and 'secondary particle' means a secondary structure formed by the aggregation of multiple primary particles.

[0070] In this specification, the content of each element in the complex transition metal hydroxide may be measured through ICP (Inductive Coupled Plasma) analysis using an inductively coupled plasma optical emission spectrometer (ICP-OES; PerkinElmer, Optima 8000DV).

[0071] In this specification, the average particle diameter can be defined as the particle diameter corresponding to 50% of the volume cumulative distribution in the particle size distribution curve (graph curve of particle size distribution) of each particle. The average particle diameter 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 (Microtrac, S3500), measuring the difference in diffraction patterns according to particle size when the particles pass through the laser beam, calculating the particle size distribution, and calculating the particle diameter at the point where it becomes 50% of the volume cumulative distribution according to the particle diameter in the measuring device.

[0072] In this specification, the average aspect ratio of primary particles present on the particle surface may be measured by first selecting the shape of one primary particle to be measured from an SEM image of the particle, and then using an eigenvector to measure the aspect ratio, i.e., the ratio of the major axis to the minor axis, by calculating the average of the aspect ratios for dozens of primary particles for each particle.

[0073]

[0074] Method for manufacturing a cathode active material precursor

[0075] Hereinafter, a method for manufacturing a positive electrode active material precursor according to the present invention will be described.

[0076]

[0077] The method for producing a positive electrode active material precursor according to the present invention comprises the steps of (A) mixing a complex transition metal-containing solution, a basic aqueous solution, and an ammonium cation complex forming agent to produce a precipitate through a coprecipitation reaction; (B) separating and washing the precipitate to obtain a preliminary complex transition metal hydroxide; and (C) immersing the preliminary complex transition metal hydroxide in an aqueous solution having a pH of 12 to 14 to produce a surface-treated complex transition metal hydroxide; wherein step (C) is performed for 7 to 48 hours.

[0078] Meanwhile, when the positive electrode active material precursor contains cracks, there are problems such as cracks growing in the positive electrode active material manufactured from the positive electrode active material precursor, which deteriorates the life characteristics, lithium insertion becoming uneven, secondary phases being generated during charge / discharge, and output characteristics being deteriorated, and there are problems such as deterioration of the life characteristics, output characteristics, capacity characteristics, etc. of the secondary battery manufactured from the positive electrode active material precursor. Specifically, when the proportion of particles with cracks among all particles of the positive electrode active material precursor exceeds 10%, there is a problem that cracks grow in the positive electrode active material manufactured from the positive electrode active material precursor, which aggravates the deterioration of the life characteristics and output characteristics.

[0079]

[0080] The inventors of the present invention have conducted repeated research to solve this problem and have found that when a preparative complex transition metal hydroxide is immersed in a strong base, i.e., an aqueous solution having a pH of 12 to 14, for a certain period of time, preparative complex transition metal hydroxide fine particles with less growth, especially, D min Inland D 10 The present invention was completed by finding that a cathode active material precursor can be manufactured by dissolving fine particles in an aqueous solution and filling the cracks of a pre-complex transition metal hydroxide, thereby eliminating the presence of cracks in most of the particles.

[0081]

[0082] The positive electrode active material precursor according to the present invention described above can be manufactured by appropriately controlling the type of the composite transition metal-containing solution, the type of the basic aqueous solution, the type of the ammonium cation complex forming agent, the mixing ratio of the solutions, etc.

[0083]

[0084] Hereinafter, each step of the present invention will be described in detail.

[0085]

[0086] (A) Step

[0087] It includes step (A) of preparing a precipitate through a coprecipitation reaction by mixing a solution containing a complex transition metal, an aqueous basic solution, and an ammonium cation complex forming agent.

[0088] The complex transition metal-containing solution may contain nickel (Ni) and at least one selected from cobalt (Co) and manganese (Mn).

[0089] The above-mentioned composite transition metal-containing solution can be prepared by dissolving a transition metal-containing raw material in a solvent such as water, and for example, can be prepared by dissolving a nickel (Ni)-containing raw material, a cobalt (Co)-containing raw material, and a manganese (Mn)-containing raw material in water. That is, the above-mentioned composite transition metal-containing solution includes a nickel (Ni)-containing raw material, and may include a cobalt (Co)-containing raw material, and a manganese (Mn)-containing raw material. In addition, if necessary, the above-mentioned composite transition metal-containing solution may further include a metal-containing raw material containing a metal other than Ni, Co, and Mn (for example, at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo, and Zr).

[0090] The above nickel (Ni)-containing raw material may be at least one selected from the group consisting of NiO, Ni(OH)2, NiOㆍOH, NiCO3ㆍ2Ni(OH)2ㆍ4H2O, NiC2O4ㆍ2H2O, Ni(NO3)2ㆍ6H2O, fatty acid nickel, and nickel halides, and a mixture of one or two or more of these may be used. Specifically, NiSO4 may be used as the nickel-containing raw material when solubility, economy, and ease of manufacturing process are taken into consideration.

[0091] The above cobalt (Co)-containing raw material may be at least one selected from the group consisting of Co(OH)2, Co3O4, CoOㆍOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O, or Co(SO4)2ㆍ7H2O, fatty acid cobalt, and cobalt halides, and a mixture of one or two or more of these may be used. Specifically, CoSO4 may be used as the cobalt-containing raw material when solubility, economy, and ease of manufacturing process are taken into consideration.

[0092] The manganese (Mn)-containing raw material may be at least one selected from the group consisting of MnCO3, Mn2O3, MnO2, Mn3O4, Mn(NO3)2, manganese acetate, manganese dicarboxylate, manganese citrate, manganese salts of fatty acid manganese, oxyhydroxides, and halides of manganese chloride, and a mixture of one or two or more thereof may be used. Specifically, MnSO4 may be used as the manganese-containing raw material when solubility, economy, and ease of manufacturing process are taken into consideration.

[0093] Nickel (Ni)-containing raw materials, cobalt (Co)-containing raw materials, and manganese (Mn)-containing raw materials can be used in appropriate amounts considering the content of each metal element in the final manufactured complex transition metal hydroxide.

[0094]

[0095] The above-mentioned basic aqueous solution may be prepared using a basic compound. The basic compound may be at least one compound selected from the group consisting of NaOH, KOH, and Ca(OH)2, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. In this case, the solvent may be water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water.

[0096]

[0097] Meanwhile, the ammonium cation complex forming agent may include at least one compound selected from the group consisting of NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. At this time, as the solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water may be used.

[0098]

[0099] When a complex transition metal-containing solution, a basic aqueous solution, and an ammonium cation complex forming agent are introduced into a reactor as described above, the transition metal in the complex transition metal-containing solution generates precursor particles in the form of a preliminary complex transition metal hydroxide through a coprecipitation reaction.

[0100]

[0101] At this time, the basic aqueous solution can be added in an amount such that the pH of the reaction solution becomes within the desired range.

[0102] The above coprecipitation reaction may be performed at a pH of 10 to 13. Specifically, the coprecipitation reaction may be performed at a pH of 10 or higher, 10.5 or higher, 11 or higher, or 11.5 or higher, and at a pH of 12 or lower, 12.5 or lower, 12.7 or lower, or 13 or lower. When the pH is within the above range, formation of new nuclei and growth of existing nuclei of particles occur appropriately, thereby producing small-particle-diameter and large-particle-diameter precursors for producing bimodal cathode active materials. Meanwhile, cracks may occur in the large-particle-diameter precursor as the particle size increases.

[0103] The above-mentioned coprecipitation reaction may be performed for 50 to 150 hours. Specifically, the above-mentioned coprecipitation reaction may be performed for 50 hours or more, 55 hours or more, 60 hours or more, 65 hours or more, 70 hours or more, 75 hours or more, 80 hours or more, 85 hours or more, 90 hours or more, 95 hours or more, or 100 hours or more, and 105 hours or less, 110 hours or less, 115 hours or less, 120 hours or less, 125 hours or less, 130 hours or less, 135 hours or less, 140 hours or less, 145 hours or less, or 150 hours or less. When the coprecipitation reaction is performed for the above-mentioned time, the formation of new nuclei of particles and the growth of existing nuclei can occur appropriately, thereby producing small-particle-diameter and large-particle-diameter precursors for producing a bimodal cathode active material. Meanwhile, cracks may occur in the large-particle-diameter precursor as the particle size increases.

[0104]

[0105] (B) Step

[0106] Thereafter, a step of separating and washing the precipitate to obtain a preliminary complex transition metal hydroxide is included.

[0107]

[0108] In the above step (A), when the preliminary complex transition metal hydroxide particles grow to the desired size, the coprecipitation reaction is terminated, and the precipitate is separated and washed to obtain the preliminary complex transition metal hydroxide. The coprecipitation reaction termination time is, for example, when the particle size of the positive electrode active material precursor particles is the average particle size (D) of the target precursor particles. 50 ) is desirable.

[0109] The process of separating the above sediment can be performed using equipment such as, for example, vacuum filtration, a filter press, a centrifuge, etc.

[0110] The above washing may be a process for removing byproducts present on the surface of the precipitate produced as a result of the co-precipitation reaction in order to obtain the desired preliminary complex transition metal hydroxide particles. If the above washing is not performed, there is a problem in that byproducts such as Na, S, H, and O become gases or cause side reactions during the calcination for manufacturing the positive electrode active material.

[0111] The above washing can be performed by, for example, placing the sediment in a washing solution such as water, distilled water or ethanol and stirring it.

[0112] The above-mentioned washing solution may be at least one selected from water, distilled water, and ethanol, but is not limited thereto. Specifically, the washing solution may be distilled water, in which case the byproduct can be sufficiently dissolved at room temperature to effectively obtain the desired preliminary complex transition metal hydroxide.

[0113] The temperature of the cleaning solution used in the above cleaning process may be 40°C to 80°C. Specifically, the temperature of the cleaning solution may be 40°C or higher, 45°C or higher, 50°C or higher, 55°C or higher, or 60°C or higher, and may be 65°C or lower, 70°C or lower, 75°C or lower, or 80°C or lower. And, the cleaning time may be 0.2 hours to 1 hour. Specifically, the cleaning time may be 0.2 hours or higher, 0.3 hours or higher, 0.4 hours or higher, or 0.5 hours or higher, and may be 0.6 hours or lower, 0.7 hours or lower, 0.8 hours or lower, 0.9 hours or lower, or 1 hour or lower, but is not limited thereto.

[0114] Additionally, the washing solution may be used in an amount of 500 to 1,500 parts by weight per 100 parts by weight of the sediment. Specifically, the washing solution may be used in an amount of 500 parts by weight or more, 550 parts by weight or more, 600 parts by weight or more, 650 parts by weight or more, 700 parts by weight or more, 750 parts by weight or more, 800 parts by weight or more, 850 parts by weight or more, 900 parts by weight or more, 950 parts by weight or more, or 1,000 parts by weight or more, and 1,050 parts by weight or less, 1,100 parts by weight or less, 1,150 parts by weight or less, 1,200 parts by weight or less, 1,250 parts by weight or less, 1,300 parts by weight or less, 1,350 parts by weight or less, 1,400 parts by weight or less, 1,450 parts by weight or less, or 1,500 parts by weight or less, based on 100 parts by weight of the sediment, but is not limited thereto. When the above-mentioned precipitate and washing solution are used in the above-mentioned amount range, the desired preliminary complex transition metal hydroxide can be effectively obtained.

[0115]

[0116] When preparing a large-diameter preliminary composite transition metal hydroxide for the purpose of manufacturing a bimodal cathode active material, cracks may occur as the particle size increases. The preliminary composite transition metal hydroxide has a crack, i.e., a region where the particle surface is broken (cracked) and can be distinguished from a linear particle boundary of a certain size or larger through boundary information learning in an image observed with a scanning electron microscope (SEM) at 0.5K magnification, or a region that appears black or a region that appears darker than the adjacent region in an image observed with a scanning electron microscope (SEM) at 0.5K magnification.

[0117]

[0118] According to one embodiment of the present invention, the preliminary complex transition metal hydroxide may have a composition represented by the following chemical formula 1.

[0119] [Chemical Formula 1]

[0120] Ni a Cob Mn c M 1 d (OH)2

[0121] In the above chemical formula 1,

[0122] M 1 is at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr,

[0123] 0 <a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤0.1, a+b+c+d=1이다.

[0124] Above M 1 is a doping element, specifically the above M 1 M may be at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr. 1 Although it is not essential to include it, if included in an appropriate amount, it can secure the stability of the positive electrode active material precursor and improve the life characteristics, charge / discharge characteristics, and high voltage characteristics of the secondary battery manufactured therefrom.

[0125] Meanwhile, the above a may be greater than 0, 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.5 or more, or 0.55 or more, and may be 0.6 or less, 0.65 or less, 0.7 or less, 0.75 or less, 0.8 or less, 0.85 or less, 0.9 or less, 0.95 or less, or 1.0 or less. Specifically, when a is 0.55 to 0.95, high-capacity characteristics and high energy density per unit volume can be realized.

[0126] The above b may be 0 or more, 0.04 or more, 0.05 or more, 0.1 or more, 0.15 or more, or 0.2 or more, and may be 0.25 or less, 0.3 or less, 0.35 or less, 0.4 or less, 0.45 or less, 0.5 or less, 0.55 or less, 0.6 or less, 0.65 or less, 0.7 or less, 0.75 or less, 0.8 or less, 0.85 or less, 0.9 or less, 0.95 or less, or 1 or less. Specifically, when b is 0.04 to 0.2, the stability of the secondary battery can be improved.

[0127] The above c may be 0 or more, 0.04 or more, 0.05 or more, 0.1 or more, 0.15 or more, or 0.2 or more, and may be 0.25 or less, 0.3 or less, 0.35 or less, 0.4 or less, 0.45 or less, 0.5 or less, 0.55 or less, 0.6 or less, 0.65 or less, 0.7 or less, 0.75 or less, 0.8 or less, 0.85 or less, 0.9 or less, 0.95 or less, or 1 or less. Specifically, when c is 0.04 to 0.3, the life characteristics of the secondary battery can be improved.

[0128] The above d may be 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and may be 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.10 or less. When d satisfies the above range, the stability of the positive electrode active material precursor can be secured, thereby improving the life characteristics, charge / discharge characteristics, high voltage characteristics, etc. of the secondary battery manufactured therefrom.

[0129]

[0130] According to one embodiment of the present invention, the preliminary complex transition metal hydroxide has an average particle diameter (D') 50 ) may be 7㎛ to 20㎛. Specifically, the average particle diameter (D') 50) may be 7㎛ or more, 8㎛ or more, 9㎛ or more, 10㎛ or more, 11㎛ or more, 12㎛ or more, 13㎛ or more, or 14㎛ or more, and may be 15㎛ or less, 16㎛ or less, 17㎛ or less, 18㎛ or less, 19㎛ or less, or 20㎛ or less. The average particle diameter (D') of the preparative complex transition metal hydroxide 50 ) When the above range is satisfied, a large-diameter precursor can be manufactured for manufacturing a bimodal positive electrode active material, and when the large-diameter precursor and the small-diameter precursor are mixed and the calcined positive electrode active material is applied to the positive electrode, the composite density can be improved through a bimodal distribution while maintaining adhesive strength.

[0131]

[0132] According to one embodiment of the present invention, the preliminary composite transition metal hydroxide is in the form of secondary particles formed by agglomeration of primary particles. In addition, the primary particles may have an average aspect ratio of 1.5 to 1.9. Specifically, the primary particles of the preparative complex transition metal hydroxide may have an average aspect ratio of 1.5 or more, 1.51 or more, 1.52 or more, 1.53 or more, 1.54 or more, 1.55 or more, 1.56 or more, 1.57 or more, 1.58 or more, 1.59 or more, 1.6 or more, 1.61 or more, 1.62 or more, 1.63 or more, 1.64 or more, 1.65 or more, 1.66 or more, 1.67 or more, 1.68 or more, 1.69 or more, or 1.7 or more, and 1.71 or less, 1.72 or less, 1.73 or less, 1.74 or less, 1.75 or less, 1.76 or less, 1.77 or less, 1.78 or less, 1.79 or less, 1.8 or less, 1.81 or less, It may be 1.82 or less, 1.83 or less, 1.84 or less, 1.85 or less, 1.86 or less, 1.87 or less, 1.88 or less, 1.89 or less, or 1.9 or less. When the average aspect ratio of the primary particles of the preliminary composite transition metal hydroxide is within the above range, a positive electrode active material having improved cycle characteristics while maintaining capacity can be manufactured. The primary particles may have a shape other than a sphere, such as a needle shape, a plate shape, or a combination thereof.

[0133]

[0134] Meanwhile, according to one embodiment of the present invention, the preliminary composite transition metal hydroxide may have a ratio of particles having cracks among all particles of the preliminary composite transition metal hydroxide of 20% to 50%. Specifically, the ratio of particles having cracks among all particles of the preliminary composite transition metal hydroxide may be 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more, and may be 41% or less, 42% or less, 43% or less, 44% or less, 45% or less, 46% or less, 47% or less, 48% or less, 49% or less, or 50% or less. When a large-diameter precursor is manufactured for the purpose of manufacturing a bimodal cathode active material, cracks may occur as the particle size increases. When the ratio of particles having cracks among all particles in the cathode active material precursor is above a certain range, there is a problem that the life characteristics of the secondary battery ultimately manufactured therefrom are inferior. When the ratio of the number of particles having cracks among the total particles of the above-mentioned composite transition metal hydroxide is within the above range, after the surface treatment in step (C) described later in the present specification, there may be almost no particles having cracks in the positive electrode active material precursor.

[0135]

[0136] (C) Step

[0137] Thereafter, the step of preparing a surface-treated complex transition metal hydroxide by immersing the preliminary complex transition metal hydroxide in an aqueous solution having a pH of 12 to 14 is included; and the step (C) is performed for 7 to 48 hours.

[0138]

[0139] The above-mentioned preliminary complex transition metal hydroxide may be in a state before drying after washing, or may be in a dried powder state.

[0140]

[0141] The pH of the aqueous solution is 12 to 14. Specifically, the pH of the aqueous solution may be 12 or more, 12.1 or more, 12.2 or more, 12.3 or more, 12.4 or more, 12.5 or more, 12.6 or more, 12.7 or more, or 12.8 or more, and may be 12.9 or less, 13 or less, 13 or less, 13.1 or less, 13.2 or less, 13.3 or less, 13.4 or less, 13.5 or less, 13.6 or less, 13.7 or less, 13.8 or less, 13.9 or less, or 14 or less. When the pH is within the above range, the fine particles are dissolved, thereby improving cracking of large-diameter particles. Specifically, when the pH is 12.9 to 13.5, damage to the positive electrode active material precursor particles can be minimized, and the preparatory composite transition metal hydroxide particles can be dissolved economically and efficiently to produce a crack-free composite transition metal hydroxide. When supported at a pH lower than 12, there is the problem of a long time required for surface treatment.

[0142] The above aqueous solution may be prepared using a basic compound. The basic compound may be at least one compound selected from the group consisting of NaOH, KOH, and Ca(OH)2, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. In this case, the solvent may be water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that is uniformly miscible with water. Specifically, considering economic efficiency and ease of manufacturing process, an aqueous NaOH solution may be used.

[0143] At this time, the concentration of the aqueous solution may be 0.05 M to 1 M, specifically 0.08 M to 0.2 M, but is not limited thereto.

[0144]

[0145] Meanwhile, the step (C) is performed for 7 to 48 hours. Specifically, the step (C) may be performed for 7 hours or more, and 25 hours or less, 30 hours or less, 35 hours or less, 40 hours or less, 45 hours or less, or 48 hours or less. When the time for performing the step (C) is within the above range, the effect of crack improvement can be efficiently and appropriately achieved. Specifically, the less-grown pre-complex transition metal hydroxide fine particles are dissolved in an aqueous solution, and the cracks of the pre-complex transition metal oxide are filled, so that a positive electrode active material precursor having no cracks in most of the particles can be manufactured. When the time for performing the step (C) is less than 7 hours, the fine particles are not sufficiently dissolved in the aqueous solution, which causes a problem in that the cracks of the pre-complex transition metal oxide are not sufficiently improved, and when the time for performing the step (C) is more than 48 hours, it is not efficient, and rather, the positive electrode active material precursor is dissolved in the aqueous solution, which causes a problem in that the yield is reduced.

[0146]

[0147] According to one embodiment of the present invention, the step (C) may be performed at a temperature of 20°C to 80°C. Specifically, the step (C) may be performed at a temperature of 20°C or higher, 30°C or higher, or 40°C or higher, and 50°C or lower, 60°C or lower, 70°C or lower, or 80°C or lower. When the temperature is within the above range, the effect of crack improvement can be efficiently and appropriately achieved, and the manufacturing process is economical and stable, and the reaction rate can be controlled to improve the quality of the positive electrode active material precursor.

[0148]

[0149] According to one embodiment of the present invention, the loading amount of the preliminary composite transition metal hydroxide may be 20 parts by weight to 120 parts by weight based on 100 parts by weight of the aqueous solution. Specifically, the loading amount may be 10 parts by weight or more, 20 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, or 50 parts by weight or more, and may be 60 parts by weight or less, 70 parts by weight or less, 80 parts by weight or less, 90 parts by weight or less, 100 parts by weight or less, 110 parts by weight or less, or 120 parts by weight or less based on 100 parts by weight of the aqueous solution. When the loading amount is within the above range, damage to the positive electrode active material precursor particles can be minimized, and fine particles of the preliminary composite transition metal hydroxide can be dissolved economically and efficiently to produce a composite transition metal hydroxide in which most particles do not have cracks.

[0150]

[0151] Meanwhile, the composite transition metal hydroxide has a ratio of particles having cracks among the total particles of the composite transition metal hydroxide of 10% or less. Specifically, the ratio of particles having cracks among the total particles of the composite transition metal hydroxide may be 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less. In particular, when the ratio of particles having cracks among the total particles of the composite transition metal hydroxide of 5% or less, the life characteristics of the positive active material manufactured using the positive active material precursor can be improved, and the particle size of the positive active material can be made uniform, thereby facilitating the control of the positive electrode mixture density. When the ratio exceeds 10%, cracks grow in the positive active material, which deteriorates the life characteristics, and the insertion of lithium becomes uneven, which causes problems such as the generation of a secondary phase during charge and discharge, and the deterioration of the output characteristics, making it unsuitable for use in a battery.

[0152]

[0153] Cathode active material precursor

[0154] Hereinafter, a positive electrode active material precursor according to the present invention will be described.

[0155] The positive electrode active material precursor according to the present invention may be manufactured by the method for manufacturing the positive electrode active material precursor.

[0156]

[0157] The cathode active material precursor according to the present invention comprises a composite transition metal hydroxide having a composition represented by the following chemical formula 2, wherein the composite transition metal hydroxide is in the form of secondary particles in which primary particles are aggregated, the primary particles have an average aspect ratio of 1.8 to 2.2, and the composite transition metal hydroxide has a ratio of particles having cracks among all particles of the composite transition metal hydroxide of 10% or less.

[0158] [Chemical Formula 2]

[0159] Ni p Co q Mn r M 2 s (OH)2

[0160] In the above chemical formula 2,

[0161] M 2 is at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr,

[0162] 0 <p≤1, 0≤q≤1, 0≤r≤1, 0≤s≤0.1, p+q+r+s=1이다.

[0163] Above M 2 is a doping element, specifically the above M 2 M may be at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr. 2 Although it is not essential to include it, if included in an appropriate amount, it can secure the stability of the positive electrode active material precursor and improve the life characteristics, charge / discharge characteristics, and high voltage characteristics of the secondary battery manufactured therefrom.

[0164] Meanwhile, the above p may be greater than 0, 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, or 0.55 or more, and may be 0.6 or less, 0.65 or less, 0.7 or less, 0.75 or less, 0.8 or less, 0.85 or less, 0.9 or less, 0.95 or less, or 1.0 or less. Specifically, when p is 0.55 to 0.95, high-capacity characteristics and high energy density per unit volume can be realized.

[0165] The above q may be 0 or more, 0.04 or more, 0.05 or more, 0.1 or more, 0.15 or more, or 0.2 or more, and may be 0.25 or less, 0.3 or less, 0.35 or less, 0.4 or less, 0.45 or less, 0.5 or less, 0.55 or less, 0.6 or less, 0.65 or less, 0.7 or less, 0.75 or less, 0.8 or less, 0.85 or less, 0.9 or less, 0.95 or less, or 1 or less. Specifically, when q is 0.04 to 0.2, the stability of the secondary battery can be improved.

[0166] The above r may be 0 or more, 0.04 or more, 0.05 or more, 0.1 or more, 0.15 or more, or 0.2 or more, and may be 0.25 or less, 0.3 or less, 0.35 or less, 0.4 or less, 0.45 or less, 0.5 or less, 0.55 or less, 0.6 or less, 0.65 or less, 0.7 or less, 0.75 or less, 0.8 or less, 0.85 or less, 0.9 or less, 0.95 or less, or 1 or less. Specifically, when r is 0.04 to 0.3, the life characteristics of the secondary battery can be improved.

[0167] The above s may be 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more, and may be 0.06 or less, 0.07 or less, 0.08 or less, 0.09 or less, or 0.10 or less. When s satisfies the above range, the stability of the positive electrode active material precursor can be secured, thereby improving the life characteristics, charge / discharge characteristics, high voltage characteristics, etc. of the secondary battery manufactured therefrom.

[0168]

[0169] Meanwhile, the above-mentioned composite transition metal hydroxide is in the form of secondary particles formed by agglomeration of primary particles. In addition, the primary particles have an average aspect ratio of 1.8 to 2.2. Specifically, the primary particles of the above-described composite transition metal hydroxide may have an average aspect ratio of 1.8 or more, 1.81 or more, 1.82 or more, 1.83 or more, 1.84 or more, 1.85 or more, 1.86 or more, 1.87 or more, 1.88 or more, 1.89 or more, and 1.9 or less, 1.91 or less, 1.92 or less, 1.93 or less, 1.94 or less, 1.95 or less, 1.96 or less, 1.97 or less, 1.98 or less, 1.99 or less, 2.0 or less, 2.01 or less, 2.02 or less, 2.03 or less, 2.04 or less, 2.05 or less, 2.06 or less, 2.07 or less, 2.08 or less, 2.09 or less, 2.1 or less. It may be 2.11 or less, 2.12 or less, 2.13 or less, 2.14 or less, 2.15 or less, 2.16 or less, 2.17 or less, 2.18 or less, 2.19 or less, or 2.2 or less. When the average aspect ratio of the composite transition metal hydroxide primary particles is within the above range, a positive electrode active material having improved cycle life characteristics while maintaining capacity can be manufactured. The primary particles may have a shape other than a sphere, such as a needle shape, a plate shape, or a combination thereof. When the average aspect ratio is less than 1.8, the particle shape of the composite transition metal hydroxide is uneven, so when the positive electrode active material manufactured therefrom is rolled, there is a problem that the positive electrode active material is broken or cracked. When the average aspect ratio is more than 2.2, the surface density of the composite transition metal hydroxide is low, so the positive electrode active material manufactured therefrom has a low surface density and a high specific surface area, so the contact area with the electrolyte increases, and there is a problem that the life characteristics of the positive electrode active material manufactured therefrom are inferior.

[0170]

[0171] Meanwhile, the composite transition metal hydroxide has a ratio of particles having cracks among the total particles of the composite transition metal hydroxide of 10% or less. Specifically, it may be 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less. In particular, when the ratio of particles having cracks among the total particles of the composite transition metal hydroxide of 5% or less, the physical and chemical structural stability of the positive electrode active material manufactured with the composite transition metal hydroxide is improved, so that the life characteristics can be improved. When the ratio exceeds 10%, cracks grow in the positive electrode active material, which deteriorates the life characteristics, and the insertion of lithium becomes uneven, which causes problems such as the generation of a secondary phase during charge and discharge, and the deterioration of the output characteristics, making it unsuitable for use in a battery.

[0172]

[0173] According to one embodiment of the present invention, the composite transition metal hydroxide has an average particle diameter (D 50 ) may be 7㎛ to 20㎛. Specifically, the composite transition metal hydroxide has an average particle diameter (D 50 ) may be 7㎛ or more, 8㎛ or more, 9㎛ or more, 10㎛ or more, 11㎛ or more, 12㎛ or more, 13㎛ or more, or 14㎛ or more, and may be 15㎛ or less, 16㎛ or less, 17㎛ or less, 18㎛ or less, 19㎛ or less, or 20㎛ or less. The average particle diameter (D of the composite transition metal hydroxide 50 ) When the above range is satisfied, when applying the anode, the composite density can be improved through a bimodal distribution while maintaining the adhesive strength.

[0174]

[0175] positive electrode active material

[0176] The present invention can provide a positive electrode active material manufactured using a positive electrode active material precursor manufactured by the above-described positive electrode active material precursor manufacturing method.

[0177]

[0178] The above positive electrode active material can be manufactured by mixing the positive electrode active material precursor with a lithium raw material and then calcining it.

[0179] Examples of the lithium raw material include lithium-containing carbonates (e.g., lithium carbonate, etc.), hydrates (e.g., lithium hydroxide hydrate (LiOH·H2O)), hydroxides (e.g., lithium hydroxide, etc.), nitrates (e.g., lithium nitrate (LiNO3)), chlorides (e.g., lithium chloride (LiCl)), etc., and one of these may be used alone or a mixture of two or more may be used.

[0180] Meanwhile, the above mixing may be performed by dry mixing or wet mixing. Each lithium raw material and cathode active material precursor may be used in an appropriate amount considering the content of each metal element in the lithium composite transition metal oxide to be finally manufactured. For example, the cathode active material precursor and the lithium raw material may be mixed in an amount such that the molar ratio of transition metal:Li is 1:1.0 to 1.3. Specifically, the molar ratio of transition metal:Li may be mixed in an amount such that it is 1:1.0 or more, 1.01 or more, 1.02 or more, 1.03 or more, 1.04 or more, 1.05 or more, 1.06 or more, and 1.07 or less, 1.08 or less, 1.09 or less, 1.1 or less, 1.11 or less, 1.12 or less, 1.13 or less, 1.14 or less, 1.15 or less, 1.16 or less, 1.17 or less, 1.18 or less, 1.19 or less, 1.2 or less, 1.21 or less, 1.22 or less, 1.23 or less, 1.24 or less, 1.25 or less, 1.26 or less, 1.27 or less, 1.28 or less, 1.29 or less, or 1.3 or less, and among them, They can be mixed in an amount of 1:1.03 to 1:07. When the positive electrode active material precursor and the lithium raw material are mixed within the above range, residual lithium can be minimized to improve resistance characteristics and a positive electrode active material exhibiting excellent capacity characteristics can be manufactured.

[0181] The above firing can be performed at 600°C to 1,000°C. Specifically, the firing can be performed at 600°C or higher, 650°C or higher, or 700°C or higher, and 750°C or lower, 800°C or lower, 850°C or lower, 900°C or lower, 950°C or lower, or 1,000°C or lower. In addition, the firing can be performed for 6 to 24 hours. Specifically, it may be performed for, but is not limited to, 6 hours or more, 7 hours or more, 8 hours or more, 9 hours or more, 10 hours or more, 11 hours or more, or 12 hours or more, and 13 hours or less, 14 hours or less, 15 hours or less, 16 hours or less, 17 hours or less, 18 hours or less, 19 hours or less, 20 hours or less, 21 hours or less, 22 hours or less, 23 hours or less, or 24 hours or less.

[0182]

[0183] anode

[0184] Next, the present invention can provide a positive electrode including the positive electrode active material described above.

[0185]

[0186] The positive electrode comprises a positive electrode active material layer comprising a positive electrode active material including a positive electrode active material precursor according to the present invention. Specifically, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and comprising the positive electrode active material. Since the positive electrode active material has been described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0187]

[0188] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 µm to 500 µm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesive strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0189]

[0190] The above-mentioned positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material. At this time, the positive electrode active material may be included in an amount of 80 wt% to 99 wt%, more specifically 85 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer, and excellent capacity characteristics may be exhibited within this range.

[0191]

[0192] The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One type alone or a mixture of two or more types of these may be used. The conductive material may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0193]

[0194] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesive strength between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The binder may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0195]

[0196] The positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode active material described above is used. Specifically, the positive electrode can be manufactured by coating a composition for forming a positive electrode active material layer, which is manufactured by dissolving or dispersing the positive electrode active material and optionally a binder and a conductive material in a solvent, on a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive material are as described above. Alternatively, the positive electrode can be manufactured by casting the composition for forming a positive electrode active material layer on a separate support, and then laminating the film obtained by peeling it from the support on a positive electrode current collector.

[0197]

[0198] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0199]

[0200] lithium secondary battery

[0201] Next, a lithium secondary battery including the above-described positive electrode is described.

[0202] The present invention can manufacture an electrochemical device including the above-described positive electrode. The electrochemical device may be, specifically, a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.

[0203]

[0204] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is the same as described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0205]

[0206] In addition, the lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0207]

[0208] In the above lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0209] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery. For example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0210]

[0211] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0212]

[0213] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, or Al alloy; SiO β(0<β<2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0214] The above negative electrode active material may be included in an amount of 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0215]

[0216] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0217]

[0218] The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt% or less, specifically, 5 wt% 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 a chemical change in the battery, and examples thereof include 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 fiber or metal fiber; metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0219]

[0220] The negative electrode active material layer may be manufactured by applying and drying a composition for forming a negative electrode active material layer prepared by dissolving or dispersing a negative electrode active material, and optionally a binder and a conductive material in a solvent, on a negative electrode current collector, or by casting the composition for forming a negative electrode active material layer on a separate support, and then laminating the film obtained by peeling it off from the support on a negative electrode current collector.

[0221]

[0222] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without special restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0223]

[0224] In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0225] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0226] As the organic solvent, any solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); Alcohol solvents such as ethyl alcohol, isopropyl alcohol, etc.; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes, etc. can be used. Among these, carbonate solvents are preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of a battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0227]

[0228] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably used within the range of 0.1 to 5.0 M, specifically, 0.1 to 3.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0229]

[0230] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additive may be included in an amount of 0.1 to 10 wt%, specifically, 0.1 to 5 wt%, based on the total weight of the electrolyte.

[0231]

[0232] As described above, a lithium secondary battery including a cathode active material according to the present invention exhibits excellent lifespan characteristics and output characteristics, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0233] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0234] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0235] There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0236] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also be preferably used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0237]

[0238] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0239]

[0240] Example

[0241] Example 1

[0242] A 2.4 M concentration complex transition metal-containing solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in water in an amount such that the molar ratio of nickel:cobalt:manganese was 91:4.5:4.5.

[0243] The input pipes of the above complex transition metal aqueous solution, 25 wt% NaOH aqueous solution, and NH4OH aqueous solution were each connected to a 10 L continuous stirred tank reactor equipped with a filter. While adjusting the input pipes of the above complex transition metal-containing solution to 2.2 to 4.5 L / hr, the 25 wt% NaOH aqueous solution to 1.4 to 2.5 L / hr, and the 9 wt% NH4OH aqueous solution to 0.25 to 0.7 L / hr, the reactor was lowered from 50°C and pH 12.4 to 12.8 to 11.2 to 11.5, and a coprecipitation reaction was performed for 70 hours. After that, the coprecipitation reaction was performed for 50 hours while maintaining the pH at 11.4 to 11.8, to produce a precipitate. During the above co-precipitation reaction process, when the reaction solution reached 80% of the reactor volume, the filter was operated to continuously discharge the filtrate so that the water level of the reaction solution could be maintained constant, and the input amounts of the solutions were adjusted so that the pH of the reaction solution could be within the desired range.

[0244] The above precipitate was separated and washed to obtain a preliminary complex transition metal hydroxide having cracks. The preliminary complex transition metal hydroxide was Ni 0.91 Co 0.045 Mn 0.045 It has a composition represented by (OH)2 and an average particle diameter (D') 50 ) is 14.66㎛, and is in the form of secondary particles aggregated from primary particles.

[0245] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was prepared by immersing 50 kg of the above-mentioned preliminary composite transition metal hydroxide in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 13.0 at 50°C for 20 hours. The amount of the above-mentioned preliminary composite transition metal hydroxide immersed is 60 parts by weight based on 100 parts by weight of the above-mentioned aqueous solution.

[0246]

[0247] Example 2

[0248] A 2.4 M concentration complex transition metal-containing solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in water in an amount such that the molar ratio of nickel:cobalt:manganese was 55:20:25.

[0249] The input pipes of the above complex transition metal aqueous solution, 25 wt% NaOH aqueous solution, and NH4OH aqueous solution were each connected to a 10 L continuous stirred tank reactor equipped with a filter. While adjusting the input pipes of the above complex transition metal-containing solution to 0.80 to 1.5 L / hr, the 25 wt% NaOH aqueous solution to 0.5 to 0.8 L / hr, and the 9 wt% NH4OH aqueous solution to 0.10 to 0.15 L / hr, the reactor was lowered from 50°C and pH 12.0 to 12.5 to 10.8 to 11.5, and a coprecipitation reaction was performed for 30 hours. After that, the coprecipitation reaction was performed for 41 hours while maintaining the pH at 10.7 to 11.2, to prepare a precipitate. During the above co-precipitation reaction process, when the reaction solution reached 80% of the reactor volume, the filter was operated to continuously discharge the filtrate so that the water level of the reaction solution could be maintained constant, and the input amounts of the solutions were adjusted so that the pH of the reaction solution could be within the desired range.

[0250] The above precipitate was separated and washed to obtain a preliminary complex transition metal hydroxide having cracks. The preliminary complex transition metal hydroxide was Ni 0.55 Co 0.20 Mn 0.25It has a composition represented by (OH)2 and an average particle diameter (D') 50 ) is 13.31㎛, and is in the form of secondary particles aggregated from primary particles.

[0251] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was prepared by immersing 40 kg of the above-mentioned preliminary composite transition metal hydroxide in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 12.9 at 50°C for 8 hours. The amount of the above-mentioned preliminary composite transition metal hydroxide to be immersed is 50 parts by weight based on 100 parts by weight of the above-mentioned aqueous solution.

[0252]

[0253] Example 3

[0254] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was manufactured in the same manner as in Example 2, except that 40 kg of the preliminary composite transition metal hydroxide manufactured in Example 2 was immersed in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 12.9 at 50°C for 16 hours.

[0255]

[0256] Example 4

[0257] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was manufactured in the same manner as in Example 2, except that 40 kg of the preliminary composite transition metal hydroxide manufactured in Example 2 was immersed in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 12.9 at 50°C for 24 hours.

[0258]

[0259] Example 5

[0260] A 2.4 M concentration complex transition metal-containing solution was prepared by mixing NiSO4, CoSO4, and MnSO4 in water in an amount such that the molar ratio of nickel:cobalt:manganese was 55:20:25.

[0261] The input pipes of the above complex transition metal aqueous solution, 25 wt% NaOH aqueous solution, and NH4OH aqueous solution were each connected to a 10 L continuous stirred tank reactor equipped with a filter. While adjusting the input pipes of the above complex transition metal-containing solution to 5.0 to 6.5 L / hr, the 25 wt% NaOH aqueous solution to 3.0 to 4.5 L / hr, and the 9 wt% NH4OH aqueous solution to 0.8 to 1.2 L / hr, the reactor was lowered from 50°C and pH 12.2 to 12.6 to 11.5 to 12.0, and a coprecipitation reaction was performed for 20 hours. After that, the coprecipitation reaction was performed for 95 hours while maintaining the pH at 10.8 to 11.6, to prepare a precipitate. During the above co-precipitation reaction process, when the reaction solution reached 80% of the reactor volume, the filter was operated to continuously discharge the filtrate so that the water level of the reaction solution could be maintained constant, and the input amounts of the solutions were adjusted so that the pH of the reaction solution could be within the desired range.

[0262] The above precipitate was separated and washed to obtain a preliminary complex transition metal hydroxide having cracks. The preliminary complex transition metal hydroxide was Ni 0.55 Co 0.2 Mn 0.25 It has a composition represented by (OH)2 and an average particle diameter (D') 50 ) is 17.24㎛, and is in the form of secondary particles aggregated from primary particles.

[0263] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was manufactured in the same manner as in Example 5, except that 40 kg of the above-mentioned composite transition metal hydroxide was immersed in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 12.9 at 50°C for 7 hours.

[0264]

[0265] Example 6

[0266] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was manufactured in the same manner as in Example 5, except that 40 kg of the preliminary composite transition metal hydroxide manufactured in Example 5 was immersed in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 12.9 at 50°C for 18 hours.

[0267]

[0268] Comparative Example 1

[0269] The preliminary composite transition metal hydroxide prepared in Example 1 was used as a precursor for the positive electrode active material of Comparative Example 1.

[0270]

[0271] Comparative Example 2

[0272] The preliminary composite transition metal hydroxide prepared in Example 2 was used as a precursor for the positive electrode active material of Comparative Example 2.

[0273]

[0274] Comparative Example 3

[0275] The preliminary composite transition metal hydroxide prepared in Example 5 was used as a precursor for the positive electrode active material of Comparative Example 3.

[0276]

[0277] Comparative Example 4

[0278] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was prepared by immersing 40 kg of the preliminary composite transition metal hydroxide prepared in Example 5 in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution having a pH of 12.9 at 50°C for 3 hours. The amount of the preliminary composite transition metal hydroxide to be immersed is 50 parts by weight based on 100 parts by weight of the aqueous solution.

[0279]

[0280] Comparative Example 5

[0281] A surface-treated composite transition metal hydroxide (positive electrode active material precursor) was prepared by immersing 40 kg of the preliminary composite transition metal hydroxide prepared in Example 5 in 80 L of a 0.2 M, 0.63 wt% NaOH aqueous solution with a pH of 12.9 at 50°C for 5 hours. The amount of the preliminary composite transition metal hydroxide to be immersed is 50 parts by weight based on 100 parts by weight of the aqueous solution.

[0282]

[0283] Experimental example

[0284] Experimental Example 1: Confirmation of the composition ratio and residual sulfur ion content of the cathode active material precursor through ICP analysis.

[0285] For the positive electrode active material precursors manufactured in the above examples and comparative examples, the composition ratio of the positive electrode active material precursors was confirmed by the following method, and the compositions of Examples 1, 2, and 4 and Comparative Examples 1 and 2 are shown in Table 1 below.

[0286] Specifically, 5 ml of hydrochloric acid was added to 0.3 g of each of the positive electrode active material precursor particles manufactured in the above examples and comparative examples, and heated to dissolve the positive electrode active material precursor. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the positive electrode active material precursor to prepare a solution. Subsequently, the solution was diluted with deionized water to a total volume of 50 ml to prepare an analysis sample. Using ICP-OES (Optima 8000DV, Perkin Elmer), the composition of the positive electrode active material precursor present in the analysis sample was measured and shown in Table 1 below, and the residual sulfur ion content (ppm) present in the analysis sample was measured and shown in Table 2 below.

[0287] Composition Example 1Ni 0.914 Co 0.043 Mn 0.043 (OH)2 Example 2Ni 0.55 Co 0.020 Mn 0.025 (OH)2 Example 4Ni 0.55 Co0.020 Mn 0.025 (OH)2 Comparative Example 1Ni 0.91 Co 0.045 Mn 0.045 (OH)2 Comparative Example 2Ni 0.55 Co 0.020 Mn 0.025 (OH)2

[0288] Through Table 1, it was confirmed that the composition ratio of the positive electrode active material precursor manufactured in the example in which step (C) was performed and each positive electrode active material precursor manufactured in the comparative example in which step (C) was not performed was almost unchanged regardless of whether step (C) was performed.

[0289] In conclusion, it can be seen that when pre-complex transition metal hydroxides are loaded, rather than new transition metals filling the cracks to produce a cathode active material precursor in which most particles are free of cracks, the pre-complex transition metal hydroxide particles that have already been formed are dissolved in an aqueous solution and fill the cracks of the pre-complex transition metal hydroxide to produce a cathode active material precursor in which most particles are free of cracks.

[0290]

[0291] Residual sulfur ion content (ppm) Example 12,116 Comparative example 12,899

[0292] As shown in Table 2, the positive electrode active material precursor manufactured in Comparative Example 1, which is a positive electrode active material precursor manufactured by separating and washing the sediment, was confirmed to have a reduced content of residual sulfur ions in the positive electrode active material precursor manufactured in Example 1, which was subjected to the step (C) of surface treatment by immersing in an aqueous solution having a pH of 12 to 14 after separating and washing the sediment. In conclusion, when surface treatment is performed by additionally immersing in an aqueous solution having a pH of 12 to 14 after the step of separating and washing the sediment, residual sulfur ions, which are byproducts, are removed, thereby improving the life characteristics of a secondary battery manufactured therefrom.

[0293]

[0294] Experimental Example 2: Confirmation of the morphology of the positive electrode active material precursor

[0295] For each of the positive electrode active material precursors manufactured in the above examples and comparative examples, SEM images were obtained using a scanning electron microscope (SEM) (Hitach, SU3500), and the SEM images were analyzed to confirm the average aspect ratio of the primary particles present on the surface of each positive electrode active material precursor. The average aspect ratios of the primary particles present on the surface of each positive electrode active material precursor manufactured in Examples 1, 5, and 6 and Comparative Examples 1 and 3 are shown in Table 3 below, and the SEM images are shown in FIGS. 1 to 9.

[0296]

[0297] Figure 1 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Comparative Example 1.

[0298] Figure 2 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Example 1.

[0299] Figure 3 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Comparative Example 1.

[0300] Figure 4 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Example 1.

[0301] Figure 5 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Comparative Example 3.

[0302] Figure 6 is a SEM image (0.5K magnification) of the positive electrode active material precursor manufactured in Example 6.

[0303] Figure 7 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Comparative Example 3.

[0304] Figure 8 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Example 5.

[0305] Figure 9 is a SEM image (15.0K magnification) of the positive electrode active material precursor manufactured in Example 6.

[0306]

[0307] Through FIGS. 1 to 9, it was confirmed that the positive electrode active material precursors manufactured in Comparative Examples 1 and 3 were in the form of secondary particles in which primary particles were aggregated and that cracks were present. On the other hand, it was confirmed that the positive electrode active material precursors manufactured in Examples 1, 5, and 6 according to the present invention were in the form of secondary particles in which primary particles were aggregated and that the number of particles in which cracks were present was smaller than that in the Comparative Examples, or that no cracks were present.

[0308]

[0309] Average aspect ratio of primary particles Example 11.89 Example 51.82 Example 61.95 Comparative example 11.74 Comparative example 31.61

[0310] Through Table 3, it was confirmed that the positive electrode active material precursors manufactured in Comparative Examples 1 and 3, i.e., the composite transition metal hydroxides that did not perform step (C), had an average aspect ratio of primary particles of 1.5 to 1.9, and the positive electrode active material precursors manufactured in Examples 1, 6, and 7, i.e., the composite transition metal hydroxides that were surface-treated by performing step (C), had an average aspect ratio of primary particles of 1.8 to 2.2.

[0311] In conclusion, it was confirmed that the surface-treated complex transition metal hydroxide obtained by performing step (C) exhibited an increased average aspect ratio of the primary particles compared to the untreated complex transition metal hydroxide. An increase in the average aspect ratio of the primary particles is expected to increase the specific surface area, thereby improving capacity characteristics.

[0312]

[0313] Experimental Example 3: Confirmation of the ratio of particles with cracks among all particles of the positive electrode active material precursor.

[0314] For each of the positive electrode active material precursors manufactured in the above examples and comparative examples, segmentation images were obtained using SEM images and an artificial intelligence model, and the images were analyzed to determine the ratio (%) of the number of particles with cracks among the total particles of the positive electrode active material precursor. The results are shown in Table 4 below, and segmentation images for each of the positive electrode active material precursors manufactured in Examples 1 and 6 and Comparative Examples 1 and 3 are shown in FIGS. 10 to 16.

[0315] Specifically, to quantify the ratio of particles with cracks among all particles, SEM images and an artificial intelligence model (U-Net) were used. After learning the boundary information between particles and cracks with the artificial intelligence model, the shapes of particles were separated from the SEM images, and cracks within particles were defined by distinguishing them from inter-particle boundaries with a linear shape larger than a certain size through boundary information learning. The SEM images were automatically analyzed using the artificial intelligence model, and the number of particles in the total positive electrode precursor was defined by separating the shapes of particles from the extracted particle shape segmentation images in the SEM images, and the number of particles with cracks was defined according to the presence or absence of cracks within the particles from the extracted crack segmentation images, thereby calculating the ratio (%) of the number of particles with cracks among all particles of the positive electrode precursor.

[0316]

[0317] Figure 10 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 1.

[0318] Figure 11 is a segmentation image of the positive electrode active material precursor manufactured in Example 1.

[0319] Figure 12 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 3.

[0320] Figure 13 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 4.

[0321] Figure 14 is a segmentation image of the positive electrode active material precursor manufactured in Comparative Example 5.

[0322] Figure 15 is a segmentation image of the positive electrode active material precursor manufactured in Example 5.

[0323] Figure 16 is a segmentation image of the positive electrode active material precursor manufactured in Example 6.

[0324]

[0325] Through Figures 10 and 11, it was confirmed that the number of particles indicated in red on the segmentation image, i.e., particles with cracks, was significantly reduced in the positive electrode active material precursor manufactured in Example 1 in which step (C) was performed compared to the positive electrode active material precursor manufactured in Comparative Example 1 in which step (C) was not performed.

[0326] Through Figures 12 to 16, it was confirmed that the number of particles indicated in red on the segmentation image, i.e., particles with cracks, was significantly reduced in the positive electrode active material precursor manufactured in Comparative Example 3 in which step (C) was not performed and the positive electrode active material precursor manufactured in Comparative Examples 4 and 5 in which step (C) was performed for less than 7 hours, compared to the positive electrode active material precursor manufactured in Examples 5 and 6 in which step (C) was performed for 7 hours or more and 48 hours or less.

[0327]

[0328] (C) Whether step is performed (C) Time for performing step (hours) Ratio of number of particles with cracks (%) Example 1○200 Example 5○74.6 Example 6○181.6 Comparative example 1X042.3 Comparative example 3X028.8 Comparative example 4○310.2 Comparative example 5○510.5

[0329] Through Table 4, it was confirmed that the positive electrode active material precursors manufactured in Comparative Examples 1 and 3, i.e., the preliminary composite transition metal hydroxides that did not perform step (C), had a ratio of particles with cracks among the total particles of the preliminary composite transition metal hydroxide of 20% to 50%, and the positive electrode active material precursors manufactured in Comparative Examples 4 and 5, i.e., the composite transition metal hydroxides that were surface-treated by performing step (C) for less than 7 hours, had a ratio of particles with cracks among the total particles of the composite transition metal hydroxide of more than 10%.

[0330] On the other hand, it was confirmed that the composite transition metal hydroxide surface-treated by performing step (C) for 7 hours or more and 48 hours or less of the positive electrode active material precursors manufactured in Examples 1, 5 and 6 had a ratio of particles with cracks of 10% or less among the total particles of the composite transition metal hydroxide.

[0331] In conclusion, it can be seen that by immersing a preparative complex transition metal hydroxide in an aqueous solution having a pH of 12 to 14, a surface-treated cathode active material precursor having no cracks in most of the particles can be prepared.

[0332]

[0333] Experimental Example 4: Confirmation of particle size of positive electrode active material precursor

[0334] In order to measure the average particle diameter of the positive electrode active material precursor particles manufactured in Examples 1 to 3, 7 and Comparative Examples 1 to 3, the minimum particle diameter (D) of the positive electrode active material precursors manufactured in Examples 1 to 3, 7 and Comparative Examples 1 to 3 was measured using PSA (Microtrac, S3500). min ), particle diameter at the point where the volume cumulative distribution becomes 5% (D5), particle diameter at the point where the volume cumulative distribution becomes 10% (D 10 ), average particle diameter (D 50 ) and maximum particle diameter (D max ) were measured and are shown in Table 5.

[0335]

[0336] Minimum particle diameter (D min ) (㎛) Particle diameter at the point where it becomes 5% of the volume cumulative distribution (D5) (㎛) Particle diameter at the point where it becomes 10% of the volume cumulative distribution (D 10 )(㎛)Average particle diameter(D) 50 ) (㎛) Maximum particle diameter (D) max ) (㎛)Example 110.0911.3811.9514.6631.11Example 26.739.1759.9813.4727.33Example 36.749.30810.0913.5627.32Example 66.5911.4012.6917.2943.76Comparative Example 110.0911.3511.9514.6631.11Comparative Example 26.729.0259.8413.3127.33Comparative Example 36.5811.1612.5317.2443.71

[0337] Through the above Table 5, in the case of Example 1, which performed the step (C) of surface treatment by immersion in an aqueous solution having a pH of 12 to 14, compared to Comparative Example 1, which did not perform the step (C) of surface treatment by immersion in an aqueous solution having a pH of 12 to 14, it was confirmed that D5 increased from 11.35 ㎛ to 11.38 ㎛. In addition, in the case of Examples 2 and 3, which performed the step (C) of surface treatment by immersion in an aqueous solution having a pH of 12 to 14, compared to Comparative Example 2, which did not perform the step (C) of surface treatment by immersion in an aqueous solution having a pH of 12 to 14, D 10 It was confirmed that the particle size gradually increased from 9.84㎛ to 9.98㎛ and 10.09㎛, and the volume D5 gradually increased from 9.025㎛ to 9.175㎛ and 9.308㎛. In the case of Example 7, which performed the step (C) of surface treatment by immersing in an aqueous solution having a pH of 12 to 14, compared to Comparative Example 3, which did not perform the step (C) of surface treatment by immersing in an aqueous solution having a pH of 12 to 14, D 10 It was confirmed that this increased from 12.53㎛ to 12.69㎛, and D5 increased from 11.16㎛ to 11.40㎛.

[0338] In conclusion, when step (C) of surface treatment is performed by immersing in an aqueous solution having a pH of 12 to 14 after sediment separation and washing, the particle size of particles having a particle size of less than 10% of the volume cumulative distribution increases, resulting in D min Inland D 10 It can be seen that the fine particles are dissolved in the aqueous solution and fill the pre-complex transition metal hydroxide cracks.

Claims

1. (A) A step of preparing a precipitate through a coprecipitation reaction by mixing a solution containing a complex transition metal, an aqueous basic solution, and an ammonium cation complex forming agent; (B) a step of separating and washing the above precipitate to obtain a preliminary complex transition metal hydroxide; and (C) a step of preparing a surface-treated complex transition metal hydroxide by immersing the preliminary complex transition metal hydroxide in an aqueous solution having a pH of 12 to 14; A method for producing a positive electrode active material precursor, wherein the above step (C) is performed for 7 to 48 hours.

2. In claim 1, A method for producing a positive electrode active material precursor, wherein the above-mentioned preliminary complex transition metal hydroxide has a composition represented by the following chemical formula 1: [Chemical Formula 1] Ni a What b Mn c M 1 d (OH)2 In the above chemical formula 1, M 1 is at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr, 0 <a≤1, 0≤b≤1, 0≤c≤1, 0≤d≤0.1, a+b+c+d=1이다.

3. In claim 1, A method for producing a positive electrode active material precursor, wherein the above a is 0.55 to 0.

95.

4. In claim 1, A method for producing a positive electrode active material precursor, wherein the above b is 0.04 to 0.

2.

5. In claim 1, A method for producing a positive electrode active material precursor, wherein the above c is 0.04 to 0.

3.

6. In claim 1, The above preliminary complex transition metal hydroxide has an average particle diameter (D') 50 ) A method for manufacturing a positive electrode active material precursor having a diameter of 7㎛ to 20㎛.

7. In claim 1, A method for producing a positive electrode active material precursor, wherein the above-mentioned composite transition metal hydroxide is in the form of secondary particles in which primary particles are aggregated, and the primary particles have an average aspect ratio of 1.5 to 1.

9.

8. In claim 1, A method for producing a positive electrode active material precursor, wherein the above-mentioned preliminary composite transition metal hydroxide has a ratio of particles having cracks among the total particles of the preliminary composite transition metal hydroxide of 20% to 50%.

9. In claim 1, A method for producing a positive electrode active material precursor having a pH of 12.9 to 13.

5.

10. In claim 1, A method for producing a positive electrode active material precursor, wherein the above step (C) is performed at a temperature of 20°C to 80°C.

11. In claim 1, A method for producing a positive electrode active material precursor, wherein the amount of the preliminary complex transition metal hydroxide supported is 20 to 120 parts by weight based on 100 parts by weight of the aqueous solution.

12. In claim 1, A method for producing a positive electrode active material precursor, wherein the composite transition metal hydroxide has a ratio of particles having cracks among all particles of the composite transition metal hydroxide of 10% or less.

13. A compound transition metal hydroxide having a composition represented by the following chemical formula 2, The above complex transition metal hydroxide is in the form of secondary particles in which primary particles are aggregated, and the primary particles have an average aspect ratio of 1.8 to 2.

2. The above composite transition metal hydroxide is a positive electrode active material precursor in which the ratio of particles having cracks among the total particles of the composite transition metal hydroxide is 10% or less: [Chemical Formula 2] Ni p What q Mn r M 2 s (OH)2 In the above chemical formula 2, M 2 is at least one selected from Al, Cu, Fe, B, Cr, V, Ti, Ta, Nb, Y, Mo and Zr, 0 <p≤1, 0≤q≤1, 0≤r≤1, 0≤s≤0.1, p+q+r+s=1이다.

14. In claim 13, A positive electrode active material precursor wherein the above p is 0.55 to 0.

95.

15. In claim 13, A positive electrode active material precursor wherein the above q is 0.04 to 0.

2.

16. In claim 13, A positive electrode active material precursor wherein the above r is 0.04 to 0.

3.

17. In claim 13, The above composite transition metal hydroxide is a positive electrode active material precursor in which the ratio of particles having cracks among all particles of the above composite transition metal hydroxide is 5% or less.

18. In claim 13, The above complex transition metal hydroxide has an average particle diameter (D 50 ) is a positive electrode active material precursor having a diameter of 7㎛ to 20㎛.

Images