Hydroxide-containing powder material and method for producing the same

Abstract

The present invention relates to a powder material comprising a hydroxide or oxyhydroxide of one or more metal elements for preparing a positive electrode active material for a secondary battery, wherein the one or more metal elements comprise at least one of Ni, Co, and Mn; the material comprises secondary particles comprising a plurality of primary particles; the material has a median particle size D50 of 3.0 μm to 20.0 μm as determined by laser diffraction; the primary particles have a particle-based thickness distribution determined by measuring the primary particle thickness of images taken by SEM, the thickness distribution having a median thickness of 180 nm to 600 nm; and the material has a span value (D90-D10) / D50 of at most 0.6, preferably at most 0.4, and more preferably at most 0.2.

Description

[Technical Field]

[0001] The present invention relates to a metal hydroxide that can be used as a precursor for a cathode active material for a secondary battery, and a method for producing the same. In particular, but not exclusively, the present invention relates to a powder material containing a hydroxide or oxyhydroxide of at least one metal element, a method for producing the hydroxide or oxyhydroxide powder material, and a method for producing a cathode active material for a secondary battery. [Background technology]

[0002] Lithium-ion secondary batteries typically include a negative electrode (anode), an electrolyte, and a positive electrode (cathode) that contains a lithium transition metal oxide as an active material capable of intercalating and deintercalating lithium. Lithium transition metal oxides are typically prepared from prepared transition metal hydroxides, oxides, or oxyhydroxides, commonly referred to as precursors, by a co-precipitation process that involves mixing a metal salt solution with an alkaline solution in the presence of a complexing agent.

[0003] Cathode materials are a critical component of rechargeable batteries and have a significant impact on overall battery performance. Therefore, much research and development has been conducted in this field, including precursors, in recent years. Some trends in cathode material development include higher energy density, improved stability and cycling performance, and lower cost, among others. One approach to improving cathode material properties is to optimize the microstructure of the cathode material, which is directly reflected by the microstructure of its precursor. Another approach to reducing costs is to purify these precursors through more efficient and / or inexpensive processes, ideally without compromising their quality.

[0004] In view of the above, there is a constant need for further improvements in precursors and processes for manufacturing precursors. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide hydroxides or oxyhydroxides suitable as precursors to cathode active materials with improved properties. [Means for solving the problem]

[0006] In view of the first aspect, the present invention can provide a secondary particle-based powder material containing hydroxides or oxyhydroxides of one or more metal elements for preparing a positive electrode active material for a secondary battery, wherein the one or more metal elements include at least one of Ni, Co, and Mn. In other words, the present invention provides a secondary particle-based powder material compound for preparing a positive electrode active material for a secondary battery, the compound being an M-hydroxide or M-oxyhydroxide, where M represents an element(s) and M includes one or more metal elements including at least one of Ni, Co, and Mn. According to the present invention, the secondary particles include a plurality of primary particles, the material / compound has a median particle size D50 of 3.0 μm to 20.0 μm as measured by laser diffraction; the primary particles have a particle-based thickness distribution measured by measuring the primary particle thickness in an image taken by SEM, the thickness distribution having a median thickness of 180 nm to 600 nm, the median particle thickness being the thickness corresponding to when the cumulative percentage of the thickness distribution reaches 50%; the material / compound has a span value (D90-D10) / D50 of at most 0.6, preferably at most 0.4, more preferably at most 0.2, The compound is 4.0m 2 / g or less and 1.5m 2 / g or more.

[0007] Such materials / compounds according to the present invention are also referred to simply as precursors in this disclosure for ease of description. Precursors according to the present invention have a composition that can be represented by the following general formula: MO x (OH) 2-x , where 0≦x≦2, and M comprises at least one of Ni, Co, and Mn, and optionally at least one other element such as an impurity such as Na, S, etc.

[0008] According to the present invention, at least some of the secondary particles have such a morphology or microstructure, and at least some of the primary particles have two or more surfaces that form part of the exterior surface of the secondary particle, and at least some of the surfaces of the primary particles intersect with each other, and at least some of the primary particles have a stacking thickness, i.e., a particle-based thickness as defined in the present disclosure, which is the distance through a surface separated between two adjacent surfaces that do not intersect with each other.

[0009] The combined properties of the present invention, i.e., median secondary particle size, median thickness, and span in the disclosed ranges, can contribute to the low specific surface area of ​​the powder material, which in turn can contribute to the dense structure of the precursor. Furthermore, because the microstructure of the cathode material generally inherits the microstructure of its precursor, the low surface area of ​​the cathode material preferably prevents moisture and carbon uptake when exposed to air, reducing the risk of side reactions with the electrolyte in the battery.

[0010] Furthermore, the precursors of the present invention contribute to improving the properties of cathode active materials prepared from the powder materials as precursors. For example, cathode materials prepared from the precursors of the present invention exhibit lower total base and water uptake. The total base and water uptake represent undesirable surface impurities that can cause problems during application of the cathode active material in an electrochemical cell, such as gelation during slurry formation and gasification during cycling.

[0011] In view of its second aspect, the present invention also provides a method for producing a powder material comprising hydroxides or oxyhydroxides of one or more metal elements, preferably a powder material according to the first aspect of the present invention. The hydroxides or oxyhydroxides are suitable as precursors to cathode active materials. The one or more metal elements include at least one of Ni, Co, and Mn. In other words, the present invention provides a method for producing a secondary particle-based powder material compound according to the first aspect of the present invention. The method comprises: providing a stream of metal salt solution containing one or more metal elements to a reaction vessel for a period of time; During this period, the metal salt solution was mixed with an aqueous solution containing one or more alkali hydroxides and an aqueous solution of ammonia (NH 3(aq) ), thereby precipitating hydroxides of one or more metal elements to form an aqueous slurry containing hydroxide or oxyhydroxide particles of one or more metal elements; During this period, in the reaction vessel, a range of pH values ​​for the aqueous slurry, the range being 11.5 or more and 12.0 or less, preferably 11.6 or less and 11.9 or less, the pH value of the aqueous slurry being the pH value measured on a sample of the aqueous slurry after cooling to 20°C; NH3 of 12.0 g / L or more, preferably 15.0 g / L or less (aq) The concentration of, and maintaining a temperature of the aqueous slurry of at least 70°C and at most 99°C, preferably at least 80°C and at most 90°C; After the period has expired, the aqueous slurry in the reaction vessel is further processed by separating the solid fraction from the liquid fraction and drying the solid fraction to obtain the material / compound.

[0012] A period may be shown as T1-T2, which refers to the progression of time beginning at time T1, ie, at the beginning of the period, and ending at time T2, ie, at the end of the period.

[0013] Disclosed pH range, NH3 (aq) The combination of the concentration of sulfur and the reaction temperature results in a precursor with specific morphology and / or properties according to the present invention. Furthermore, the resulting precursor has reduced sulfur levels. When producing cathode active materials, the use of precursors with reduced sulfur levels is beneficial, particularly during the sintering stage of the manufacturing process.

[0014] Various embodiments according to the present invention are disclosed in the claims and in this specification. The embodiments and examples described in the claims and specification are mutually combinable unless expressly stated otherwise. Throughout this specification, when any numerical range is provided, the range also includes the endpoints unless expressly stated otherwise. [Brief explanation of the drawings]

[0015] For reference, figures are attached to provide a better understanding of the teachings of the present invention.

[0016] [Figure 1] FIG. 1 shows a screenshot of a primary particle size analysis made for a scanning electron microscope (SEM) image of the secondary particles obtained in Example 3. [Figure 2] FIG. 2 shows an SEM image of the particles obtained in Example 3. [Figure 3] FIG. 3 shows an SEM image of the particles obtained in Comparative Example 3. [Figure 4] FIG. 4 shows a graph of the misorientation angle of the grain boundary distribution of precursors B, D and F from the Examples section. DETAILED DESCRIPTION OF THE INVENTION

[0017] In the following detailed description, preferred embodiments are described in detail to enable the practice of the invention. Although the invention is described with reference to these specific preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. On the contrary, the invention includes numerous alternatives, modifications, and equivalents that will become apparent in light of the following detailed description and the accompanying drawings.

[0018] When used in the present specification and claims, the term "comprising" should not be interpreted as being limited to the means listed thereafter, nor does it exclude other elements or steps. This term must be interpreted as specifying the presence of the mentioned structure, integer, step, or component, but does not preclude the presence or addition of one or more other structures, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" is not limited to a composition consisting only of components A and B. This means that, in the context of the present invention, the only relevant components in the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of."

[0019] The term "positive electrode active material" (also known as cathode active material) as used herein and in the claims is defined as a material that is electrochemically active within a positive electrode or cathode. An active material should be understood to be a material that can capture and release Li-ions when subjected to a voltage change over a period of time.

[0020] As used in this disclosure, the term "cathode" is defined as a material that includes a cathode active material in addition to other components that are not electrochemically active, particularly a conductive agent such as a binder, such as carbon black or PVDF.

[0021] As used in this disclosure, "NH 3(aq) The term "equivalent concentration" refers to the concentration of ammonia in an aqueous solution.

[0022] Hydroxide or oxyhydroxide powder materials In a first aspect, the present invention relates to a powder material comprising a hydroxide or oxyhydroxide of one or more metal elements for preparing a positive electrode active material for a secondary battery, wherein the one or more metal elements comprise at least one of Ni, Co, and Mn. In other words, the present invention provides a secondary particle-based powder material compound for preparing a positive electrode active material for a secondary battery, the compound being an M-hydroxide or M-oxyhydroxide, wherein M comprises one or more metal elements comprising at least one of Ni, Co, and Mn. According to the present invention, the secondary particles comprise a plurality of primary particles, and the material / compound (i.e., precursor) has a median particle size D50 of 3.0 μm to 20.0 μm as measured by laser diffraction, the primary particles have a particle-based thickness distribution as measured by measuring the primary particle thickness of images taken by SEM, the thickness distribution having a median thickness of 180 nm to 600 nm, the median particle thickness being the thickness corresponding to when the cumulative percentage of the thickness distribution reaches 50%, and the material / compound (i.e., precursor) has a span value (D90-D10) / D50 of at most 0.6, preferably at most 0.4, more preferably at most 0.2, and the compound has a particle size of 4.0 μm to 5.0 μm. 2 / g or less and 1.5m 2 / g or more.

[0023] For ease of explanation, the corresponding thickness when the cumulative percentage of the thickness distribution reaches 50% may be referred to herein as p50. Similarly, the corresponding thickness when the cumulative percentage of the thickness distribution reaches 75% may be referred to herein as p75. In some embodiments, the thickness distribution has a p50 of 200 nm to 580 nm, preferably 220 nm to 570 nm. In some embodiments, the thickness distribution has a p75 of 225 nm to 800 nm, preferably 250 nm to 750 nm. The disclosed ranges of p50 and / or p75 may indicate a dense structure of primary particles. As will be understood by those skilled in the art, the cumulative percentage of the thickness distribution can be measured based on SEM images using suitable software, such as ImageJ software (ImageJ 1.52a, National Institutes of Health, USA).

[0024] In some embodiments, the precursor is 3.6 m 2 / g or less and 1.6m 2 / g or greater. As will be appreciated by those skilled in the art, the specific surface area can be measured using, for example, the Brunauer-Emmett-Teller (BET) method, for example, by using Quantachrome Monosorb.

[0025] In some embodiments, the precursor is present at a concentration of 2.0 to 2.2 g / cm 3 As will be appreciated by those skilled in the art, tap density can be performed using, for example, a J. Engelsmann Stamping volumeter STAV II instrument.

[0026] In some embodiments, the precursor has a median particle size D50 of 3.2 μm to 18.0 μm, preferably 4.0 μm to 15.0 μm. As will be appreciated by those skilled in the art, particle size distribution can be analyzed by dispersing sample particles in an aqueous medium using a Malvern Mastersizer 3000 with a Hydro MV wetting and dispersion unit.

[0027] In some embodiments, the precursor comprises: Ni with a content x, where x≧30.0 mol%, Mn with a content y, where 0≦y≦70.0 mol%, Co with a content z, where 0≦z≦40.0 mol%, Al with a content q, where 0≦q≦10.0 mol%, and one or more additional elements with a content r, where the additional elements are selected from the group consisting of B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W, Zn, and Zr, where 0≦r≦5.0 mol%, where x, y, z, q, and r are the contents expressed in mol% relative to the total molar content of M, such that x+y+z+q+r=100.0 mol%. The values ​​x, y, z, and r are measured by inductively coupled plasma (ICP) techniques. It is understood that the formula ≧0 also includes the absence of an element. In some embodiments, x≧60 mol%, or x≧70 mol%, or x≧80 mol%, or x≧90 mol%. In some embodiments, y≧20 mol% and / or z≦25 mol%.

[0028] In some embodiments, the secondary grains have grain boundaries with a misorientation angle distribution about the 0001 crystallographic axis, and the fraction F1 of grain boundaries with misorientation angles between 55° and 65° is at least 10% based on the total fraction F2 of grain boundaries with misorientation angles between 5° and 105° as determined by TEM automated crystallographic orientation maps. Preferably, fraction F1 is at least 20%, e.g., 20% to 25%, based on the total fraction F2.

[0029] Orientation microscopy techniques for characterizing defects (e.g., geometrically necessary dislocations and grain boundaries) in crystalline materials are commonly known. For example, such data can be obtained from electron backscatter diffraction (EBSD) based on diffraction images acquired by using a scanning electron microscope (SEM). For nanoscale materials, precession-assisted crystal orientation mapping techniques such as EBSD can be used, which is a transmission electron microscope (TEM)-based diffraction spot recognition technique, such as "ASTAR" commercially available tools, also known as automated crystal orientation mapping in TEM. Based on these crystal orientation microscopy techniques (i.e., crystal orientation mapping techniques), it is possible to measure the distribution and accumulation of dislocations relative to the nearest grain boundary and study the characteristics of the grain boundaries of the material. An illustrative method for obtaining the misorientation angle distribution of a precursor is exemplified in the Example K) section of this disclosure.

[0030] It is generally understood that the microstructure of a precursor carries over into the cathode active material prepared therefrom. Cathode active materials prepared from precursors according to the present invention are also observed to contain a characteristic grain boundary misorientation angle distribution, such that a preponderance of grain boundaries with misorientation angles between 55° and 65° predominates.

[0001] A misorientation angle of 60°±5° about a crystal axis indicates twinning, i.e., twin boundaries. This type of grain boundary within the cathode active material contributes little to stress generation during charge and discharge due to coherent lattice contraction on both sides of the boundary, thus advantageously resulting in fewer cracks in the cathode active material and, consequently, improved cycle life.

[0031] method In a second aspect, the present invention relates to a method for producing a powder material comprising hydroxides or oxyhydroxides of one or more metal elements, preferably a powder material according to the first aspect of the present invention. The hydroxides or oxyhydroxides are suitable as precursors to cathode active materials. The one or more metal elements include at least one of Ni, Co, and Mn. In other words, the present invention provides a method for producing a secondary particle-based powder material compound according to the first aspect of the present invention. The method comprises: providing a flow of metal salt solution containing one or more metal elements to a reaction vessel for a period of time (T1-T2); During the period (T1 to T2), the metal salt solution is mixed with an aqueous solution containing one or more alkali hydroxides and an aqueous ammonia solution (NH 3(aq) ), thereby precipitating hydroxides of one or more metal elements to form an aqueous slurry containing hydroxide or oxyhydroxide particles of one or more metal elements; During the period (T1 to T2), in the reaction vessel, a range of pH values ​​for the aqueous slurry, the range being 11.5 or more and 12.0 or less, preferably 11.6 or less and 11.9 or less, the pH values ​​of the aqueous slurry being pH values ​​measured on a sample of the aqueous slurry after cooling to 20°C; NH3 of 12.0 g / L or more, preferably 15.0 g / L or less (aq) The concentration of, and maintaining the temperature of the aqueous slurry at least 70°C and at most 99°C; After the end of the period (T2), the aqueous slurry in the reaction vessel is further processed by separating the solid fraction from the liquid fraction and drying the solid fraction to obtain the material / compound (i.e., precursor).

[0032] As will be appreciated by those skilled in the art, the pH value can be measured by using a pH meter, such as a 780 Metrohm meter. As will be appreciated by those skilled in the art, the NH3(aq) concentration can be measured by using a commercially available titration device, such as a Metrohm 848 Titrino Plus.

[0033] During the manufacturing process, the precipitated hydroxides may be partially oxidized depending on the atmosphere of the manufacturing process. Thus, the aqueous slurry may contain oxyhydroxides. Also, during drying, the hydroxide or oxyhydroxide particles from the aqueous slurry may be further partially oxidized. Note that atmospheric conditions are not required to achieve the claimed invention.

[0034] In some embodiments, during the period T1-T2, the growth rate of precipitated hydroxide in the reaction vessel is maintained at a maximum of 0.5 μm per hour, more preferably ≦0.2 μm per hour, and even more preferably ≦0.1 μm per hour.

[0035] In some embodiments, an aqueous slurry of seed particles is prepared in the reaction vessel before the start of period T1. Further nucleation may result in the formation of small particles that tend to agglomerate, which in turn alters production quality. Therefore, using seed particles instead of an in-situ seeding process can prevent undesirable further nucleation. Also, due to more available crystal surfaces as the reaction progresses, more material can be added without the risk of nucleation. According to the present invention, the use of a seed slurry in combination with the disclosed precipitation contributes to the steady growth of hydroxides on the seeds without further nucleation and agglomeration, resulting in an aqueous slurry containing homogeneously distributed hydroxide or oxyhydroxide particles with the desired median particle size, and the hydroxide or oxyhydroxide particles have excellent sphericity. The excellent sphericity of the hydroxide or oxyhydroxide particles according to the present invention remains in the cathode material when used as a precursor to the cathode material. In other words, the cathode material also has excellent sphericity. Sphericity is associated with a higher tap density.

[0036] In some embodiments, the seed particles are hydroxide or oxyhydroxide particles of at least one metal element, preferably at least one metal element comprising Ni. According to the present invention, the metal elements for the seed particles and the hydroxide or oxyhydroxide particles may be different, which provides further flexibility for carrying out the method of the present invention.

[0037] In some embodiments of the method according to the present invention, the seed particles have a median particle size D'50, and at the end of the period T2, the hydroxide or oxyhydroxide particles of the one or more metal elements have a median particle size D50, with the ratio D50 / D'50 being at least 2.00, preferably at least 3.00. A larger D50 / D'50 ratio can improve the sphericity of the resulting hydroxide or oxyhydroxide particles. In some embodiments, the D'50 is at least 0.10 μm and at most 3.0 μm. In some embodiments, the D'50 is at least 0.70 μm and at most 3.00 μm, and the D50 is at least 3.0 μm, preferably at most 5.0 μm. In some embodiments, the D'50 is at least 3.0 μm and at most 5.0 μm, and the D50 is at least 8.0 μm. In some embodiments, D50 is at most 15.0 μm, preferably at most 13.0 μm, more preferably at most 12.0 μm.

[0038] In some embodiments, D'50 is at least 0.70 μm and at most 4.00 μm, and D50 is at least 4.0 μm, preferably at most 18.0 μm. In some embodiments, D'50 is at least 4.0 μm and at most 8.0 μm, and D50 is at least 9.0 μm. In some embodiments, D50 is at most 20.0 μm.

[0039] The method for determining particle size distribution is not particularly limited. However, for example, the size distribution can be measured based on the integrated volume value measured using a laser diffraction and scattering type particle size analyzer. As the average particle size, D10, D50, and D90 can be used as the particle diameter values ​​at 10%, 50%, and 90% of the cumulative distribution, respectively, and the span value (D90 to D10) / D50 can be used as a measurement value of the distribution range.

[0040] In some embodiments, the metal salt solution has a flow rate expressed as volume per unit time, and the instantaneous (t) flow rate is expressed by Equation 1:

[0041]

number

[0042] The value of G(t) may vary depending on the embodiment. In some embodiments, the value of G(t) varies over the period T1-T2.

[0043] The upper limit of G(t), the maximum growth rate of hydroxide or oxyhydroxide particles, can depend, for example, on the characteristics of the feed pump and the characteristics of the removal system for the liquid portion of the reaction mixture / aqueous slurry (i.e., mother liquor).

[0044] In some embodiments, the value of G(t) in the equation remains constant during the period T1-T2, the flow rate of the metal salt solution is continuously increased according to Equation 1, and the growth rate of hydroxide or oxyhydroxide particles in the slurry remains constant during the period T1-T2. Thus, by continuously increasing the flow rate of the metal salt solution, a constant growth rate of the median hydroxide or oxyhydroxide particle size may be achieved. In other words, it may be possible to make the precipitation process more stable and controllable, especially when the target median particle size is large, such as at least 10 μm. With a continuous increase in flow rate, precipitation time may be reduced by up to half or a quarter compared to an otherwise similar process, while other factors remain constant, while the metal salt solution is supplied at a constant rate throughout the precipitation process.

[0045] In some embodiments, the temperature of the aqueous slurry in the reaction vessel is at least 75°C, preferably at least 80°C, more preferably at least 85°C or higher, and / or the temperature is at most 99°C, preferably at most 95°C, more preferably at most 90°C.

[0046] In some embodiments, during the period T1-T2, NH 3(aq) The concentration is maintained at 7.0 g / L or more, preferably 9.0 g / L or more, and more preferably 11.0 g / L or more. 3(aq) The concentration may facilitate slower growth in particle size (ie, slower settling) and result in a denser structure of the particles.

[0047] In some embodiments, the one or more metal elements in the metal salt solution include a precursor comprising Ni in a content b, where b is greater than or equal to 30.0 mol%, Mn in a content c, where 0≦c≦70.0 mol%, Co in a content d, where 0≦d≦40.0 mol%, Al in a content q, where 0≦e≦10.0 mol%, and one or more additional elements in a content f, where the additional element is selected from the group consisting of B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Si, Sr, Ti, Y, V, W, Zn, and Zr, where 0≦f≦5.0 mol%, where b, c, d, e, and f are the contents expressed in mol% relative to M, and b + c + d + e + f = 100.0 mol%. The values ​​b, c, d, and d are measured by inductively coupled plasma (ICP) spectroscopy. It is understood that the formula ≧0 also includes the absence of an element. In some embodiments, b≧60 mol%, or b≧70 mol%, or b≧80 mol%, or b≧90 mol%, and / or b≦99.0 mol%. In some embodiments, c≧20 mol% and / or d≦25 mol%.

[0048] Product by Process In a third aspect, the present invention relates to a hydroxide or oxyhydroxide powder material obtainable by the method according to the second aspect of the invention. In other words, the present invention also provides a secondary particle-based powder material compound obtainable by the method according to the second aspect of the invention, which compound is preferably a secondary particle-based powder material compound according to the first aspect of the invention. As will be understood by a person skilled in the art, all embodiments directed to a hydroxide or oxyhydroxide powder material according to the first aspect of the invention and / or a method according to the second aspect of the invention apply mutatis mutandis to a hydroxide or oxyhydroxide powder material obtainable by the method according to the present invention.

[0049] positive electrode active material In a fourth aspect, the present invention relates to a method for producing a cathode active material, the method comprising: mixing a powder material comprising hydroxides or oxyhydroxides of one or more metal elements, i.e. secondary particle-based powder material compounds, a lithium source, and optionally a dopant source according to the first aspect of the present invention to obtain a mixture; and optionally heating the mixture in an oxidizing atmosphere at a temperature of 650°C to 1000°C to obtain a positive electrode active material. The method further includes a heat treatment step before mixing in which the powder material is heated at a temperature of 105°C to 750°C.

[0050] use In a fifth aspect, the present invention relates to the use of a hydroxide or oxyhydroxide powder material according to the first aspect of the invention and / or a hydroxide or oxyhydroxide powder material obtainable by the method according to the second aspect of the invention in a positive electrode active material. [Example]

[0051] The present invention will be further illustrated with reference to some examples and comparative examples.In all examples, the pH value refers to the value measured at a temperature of 20°C.Furthermore, in all processes of the examples, unless otherwise indicated, a reducing atmosphere is ensured by applying a flow of nitrogen gas into the reaction vessel during the precipitation reaction.

[0052] Measurement methods used in the examples A) pH analysis The pH values ​​of the samples were measured with a 780 Metrohm meter calibrated with standards pH 7 and pH 13. The pH was measured from the samples by cooling them to 20°C, lowering a pH electrode into the sample, and waiting until the pH reading plateaued.

[0053] B)NH3 (aq) Concentration analysis NH 3(aq)Concentrations were measured from reactor samples by endpoint titration using a Metrom 848 Titrino Plus instrument. One milliliter of sample solution was added to the titration vessel. 30-40 ml of deionized water and 1 ml of 1 M NaOH were added. The sample was titrated to the endpoint with 0.1 M HCl.

[0054] C) Solid content analysis To measure the solids content of the precipitated hydroxide in the aqueous slurry, a sample taken from the aqueous slurry (reaction mixture in the examples) was mixed thoroughly, and 10-30 ml of the mixed sample was pipetted onto a filter paper, which was then washed and further filtered on a weighed 0.8 μm membrane. The filtered membrane was rinsed with DI water and then dried, and the weight of the dried membrane was measured, from which the solids content, expressed as the weight of dry hydroxide per liter of aqueous slurry in g / l, was calculated.

[0055] D) Surface area analysis The specific surface area (SA) of the sample was measured by the Brunauer-Emmett-Teller (BET) method using Quantachrome Monosorb. The powder sample was placed in a sample tube and heated at 90°C for 2 hours under nitrogen (N2) gas before measurement to remove adsorbed species. The sample was then degassed at room temperature for 5 minutes. The instrument performed the nitrogen adsorption test at 77K. The total specific surface area of ​​the sample in m2 / g was derived by obtaining the nitrogen adsorption / desorption isotherm.

[0056] E) Tap density analysis Tapped density (TD) measurements of the example samples were carried out by mechanically tapping a graduated measuring cylinder (100 ml) containing the sample (having a mass W, approximately 60-120 g). After observing the initial powder volume, further volume (cm 3 The measuring cylinder was mechanically tapped for 15 min so that no change in viscosity (V) or mass (W) was observed. TD was calculated as TD = W / V. TD measurements were performed on a J. Engelsmann Stamping volumeter STAV II instrument.

[0057] F) Secondary particle size distribution (PSD) analysis The PSD of secondary particles was measured using a Malvern Mastersizer 3000 with a Hydro MV wetting and dispersion unit after dispersing sample particles in aqueous media. To improve dispersion of metal hydroxide powders, sufficient ultrasonic irradiation and agitation were applied, and appropriate surfactants were introduced. The percentile values ​​D10, D50, and D90 are the particle diameter values ​​at 10%, 50%, and 90% of the cumulative distribution, respectively. The span value for hydroxides is (D90 - D10) / D50.

[0058] G) Metal content analysis The metal content of the hydroxides was measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES) using an Agilent ICP 720-OES instrument. One gram of powder sample from each example was dissolved in 50 mL of high-purity hydrochloric acid in an Erlenmeyer flask. The flask was covered with a watch glass and heated on a hot plate at 380 °C until the sample was completely dissolved. After cooling to room temperature, the solution and the Erlenmeyer flask's rinse water were transferred to a 250 mL volumetric flask. The volumetric flask was then filled to the 250 mL mark with deionized (DI) water, followed by thorough homogenization. An appropriate amount of the solution was pipetted and transferred to a 250 mL volumetric flask for a second dilution. The volumetric flask was then filled to the 250 mL mark with the internal standard solution and 10% hydrochloric acid, followed by homogenization. Finally, this solution was used for ICP-OES measurement. The content of metals such as Ni, Mn, and Co is expressed as mole percent of the total metal content in the measured hydroxide.

[0059] H) Primary particle size analysis The thickness of the primary particles was calculated using ImageJ software (ImageJ 1.52a, National Institutes of Health, USA) according to the following steps: Step 1) Open the file containing the SEM image of the hydroxide material at 20,000x magnification. Step 2) Set the scale according to the SEM magnification. Step 3) Select the line tool and place a line on the primary particle perpendicular to the orientation of the primary particle. Step 4) Measure the thickness of the primary particle selected from the Measurement Settings and Area boxes. The thickness is shown in the Length column. Step 5) Repeat steps 3 and 4 for 90 randomly selected particles in one image. If the number of particles in one image is less than 90, additional SEM images can be used. Figure 1 shows an example of the measurement in Example 1. Step 6) Process the data in Microsoft Excel or any numerical processing software according to the following steps shown in Table 1. a. In the "Thickness" column, sort the primary particle thickness from smallest to largest. b. In the "Total Fraction" column, calculate the fraction of each thickness that contributes to the total thickness c. In the "Cumulative" column, calculate the cumulative fraction. d. Calculate p50 and p75 from the two closest cumulative numbers, respectively, by the linear equation y=mx+c.

[0060] [Table 1]

[0061] I) Surface base analysis The determination of soluble base content by pH titration involves two steps: (a) solution preparation, and (b) pH titration. A detailed description of each step follows: Step (a): Preparation of the solution: The powder is immersed in deionized water and stirred for 10 minutes in a sealed glass flask containing 100 mL of deionized water. The amount of the positive electrode active material powder is 4 grams. After stirring, the suspension of the powder in water is filtered to dissolve the base and obtain a clear solution. Step (b): pH titration: 90 mL of the clear solution prepared in step (a) is used for pH titration using 0.1 M HCl. The flow rate is 0.5 mL / min and the pH value is recorded every 3 seconds. The pH titration profile (pH value as a function of added HCl) shows two clear equivalence points (or inflection points). The first equivalence point, around pH 7.4 (corresponding to the amount of HCl in EP1), is the first equivalence point at which OH - and CO3 2- and H + The second equivalence point near pH 4.7 (corresponding to the amount of HCl in EP2) is - and H + The base dissolved in the deionized water is assumed to be either LiOH (amount 2*EP1-EP2) or Li2CO3 (amount 2*(EP2-EP1)). The values ​​obtained for LiOH and Li2CO3 are the result of the reaction of the surface with deionized water.

[0062] J) Moisture analysis The moisture content of the positive electrode active material powder is measured using a Karl Metrohm Fischer Coulometer. One gram of the positive electrode active material powder is placed in a KF furnace at 300°C. The evaporated moisture is introduced into the KF reactor and analyzed by KF coulometry.

[0063] K) ASTAR method and misorientation plotting Prior to preparation for the focused ion beam (FIB), the sample was first coated with a 10 nm carbon layer (Leica EM ACE600 coater). Next, FIB lamellae of the sample were prepared on a Cu Omniprobe TEM grid using a Thermo Fisher Helios FIB-SEM. Final thinning of the sample was performed using 2 kV. The lamellae were approximately 1 x 5 µm in size and approximately 50-100 nm in thickness.

[0064] Analysis of the prepared samples was performed using a 200 kV Thermo Fisher Tecnai G2 transmission electron microscope (TEM) equipped with the "ASTAR" tool (automated TEM phase orientation mapping) from NanoMEGAS SPRL and Topspin software (NanoMEGAS SPRL version 3.1.1559.0), which includes a precession device "D originalSTAR" P1000. A designated area of ​​the sample was scanned by the electron beam, and precession electron diffraction (PED) patterns were collected by a CCD camera. PED patterns were acquired with a C2 aperture of 20 µm, a spot size equivalent to a beam diameter of approximately 1 nm, a camera length of 6.2 cm, a precession angle of 0.5 degrees, a resolution of 1.4 nm, a step size of 10 nm with five precessions per frame, and a scan speed of 0.05 s per frame. The total acquisition time was approximately 2–2.5 h, depending on the lamella size.

[0065] Post-processing of the acquired data was performed by acquiring and analyzing crystal orientation maps using the following software: DiffGen (ACOM-SIMAP NanoMEGAS SPRL version 2.0.10.960), Index (ACOM-SIMAP NanoMEGAS SPRL version 2.0.10.1552), MapViewer (ACOM-SIMAP NanoMEGAS SPRL version 2.0.10.474), and OIM Analysis (EDAX version 8.0). The OIM Analysis software was used for cropping, cleaning, and filtering, as well as texture analysis.

[0066] First, the orientation map was cleaned using a grain size expansion method with a grain size tolerance angle of 5 degrees and a minimum grain size of 5 pixels. The map was then filtered with a grain size tolerance angle of 5 degrees, a minimum grain size of 2 pixels, and a minimum confidence index of 10%. The grain boundary lengths for each selected angle range were calculated, starting from 5 degrees to 105 degrees with 10-degree binning. The frequency of each selected angle range, the normalized length of all grain boundaries with misorientation between 5 and 105 degrees, was plotted against the selected angle range to indicate the characteristic grain boundary misorientation within the material.

[0067] Comparative Example 1 Positive electrode active material Comparative Example 1.1 was prepared through a solid-state reaction between a lithium source and a precursor according to the following steps: 1. Preparation of Precursor A: In a 3.65 L reactor, add 2.0 L of DI water, 15 mL of 220 g / L NH 3(aq) The starting solution was prepared by adding 230 g / L of NaOH, adjusting the temperature in the reaction vessel to 65°C, and maintaining this temperature throughout the process. (aq) The solution was adjusted by adding to a value of 12.9. Next, 129 g / L NiSO 4(aq) , 80 g / L MnSO 4(aq) , and 80 g / L of CoSO 4(aq) metal sulfate solution, 220 g / L NH 3(aq) , and 230 g / L NaOH (aq) was added, and for the first 20 hours, approximately 30 kW / m 3 and the remaining part of the process requires approximately 10 kW / m 3 The precipitation reaction was carried out by mixing at a stirring power of 1000 W. The metal sulfate solutions were added using separate pumps through a static mixer. The ratio of Ni:Mn:Co was 98:2:0 at the beginning of the process and gradually changed to 74.1:20.3:5.6 towards the end of the precipitation process. During the reaction, the feed rate of the NaOH solution was adjusted so that the pH value of the reaction mixture in the reactor was constantly maintained at 11.6-11.8, and the NH3 concentration in the reaction mixture was constantly maintained at 8.0±1 g / L. 3(aq)The feed rate of the reaction mixture was adjusted. 100 minutes after the start of the reaction, it was stopped, and the reaction mixture, i.e., the aqueous slurry, was removed from the reactor. Then, 183 mL of the slurry and 1640 mL of mother liquor were returned to the reactor, and precipitation continued. Reactor samples of the reaction mixture were taken every 2 hours, and the D50 was measured therefrom. When the D50 of the reactor sample reached the target value of approximately 10 μm, the reaction was stopped, and the duration of the process was 56 hours. During the process, a concentrator was used to pump a portion of the liquid fraction of the reaction mixture out of the reactor, resulting in a slurry with a solids content of 1100 g / L. The resulting aqueous slurry of metal hydroxides was filtered and washed with 220 g / L NaOH(aq) solution and DI water at 60° C. The filter cake was dried in an oven at 120° C. for 12 hours to obtain Ni 0.85 Mn 0.10 Co 0.05 A precursor A having a total metal composition of 2. Mixing: Precursor A prepared from step 1) was mixed with LiOH and Nb2O5 in an industrial blender to obtain a first mixture with 1 mol% Nb and a lithium to metal ratio of 1.01. 3. Heating: The mixture from step 2) was heated at 705°C for 12 hours under oxygen atmosphere, followed by grinding and sieving to obtain Comparative Example 1.1. Positive electrode active material Comparative Example 1.2 was prepared according to the same method as Comparative Example 1.1, except that the heating temperature in step 3) was 755°C.

[0068] Example 1 Cathode active material Example 1.1 was prepared through a solid-state reaction between a lithium source and a precursor according to the following steps: 1. Preparation of Precursor B: Precursor B was prepared according to the same method as precursor A prepared in Comparative Example 1, except that the temperature in the reactor was maintained at 85°C. 2. Mixing: Precursor B prepared from step 1) was mixed with LiOH and Nb2O5 in an industrial blender to obtain a first mixture with 1 mol% Nb and a lithium to metal ratio of 1.01. 3. Heating: The mixture from step 2) was heated at 705°C under oxygen atmosphere for 12 hours, followed by grinding and sieving to obtain Example 1.1.

[0069] Positive electrode active material Example 1.2 was prepared according to the same method as Example 1.1, except that the heating temperature in step 3) was 755°C.

[0070] Comparative Example 2 The positive electrode active material Comparative Example 2.1 was prepared through a solid-state reaction between a lithium source and a precursor according to the following steps: 1. Preparation of Precursor C: 6 L of DI water, 160 mL of 220 g / L NH3(aq), and Ni with a D50 of 5.0 μm 0.94 Mn 0.03 Co 0.03 The starting solution was prepared by adding 100 mL of a 440 g / L aqueous slurry containing (OH)2 seed particles to a 10 L reactor and adjusting the temperature in the reactor to 75 °C, which was maintained throughout the process. Next, 220 g / L of NH 3(aq) and 230 g / L NaOH (aq) The solution was heated to approximately 30 kW / m for the first 6 hours. 3 The stirring power required for the remaining process steps is approximately 20 kW / m 3The precipitation reaction was carried out by adding 120 g / L of a metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of Ni:Mn:Co 94:3:3) while mixing at a required stirring power of 1000 rpm. The feed rate of the metal sulfate solution was 135 mL / h at the start and continuously increased to maintain a constant particle growth rate of 0.4 μm / h. During the reaction, the feed rate of the NaOH(aq) solution was adjusted to maintain a constant pH value of 11.2 ± 0.1 in the reaction mixture, and the feed rate of the NH(aq) solution was adjusted to maintain a constant NH(aq) concentration in the reaction mixture at 5.0 ± 1 g / L. Reactor samples of the reaction mixture were taken every 2 hours, and the D50 values ​​were measured from them. The reaction was stopped when the D50 value of the reactor sample reached the target value of approximately 10.0 μm. The process duration was 12 hours. A portion of the liquid fraction of the reaction mixture was pumped out of the reactor during the process by using an external condenser. The solids content of the reaction mixture in the reactor was approximately 390 g / L at the end of the process. The resulting aqueous slurry of metal hydroxide was filtered and washed with 220 g / L NaOH solution and DI water at 60° C. The filter cake was dried in an oven at 120° C. for 12 hours to obtain Precursor C. 2. Mixing: Precursor C prepared from step 1) was mixed with LiOH, Nb2O5, and Al2O3 in an industrial blender to obtain a first mixture having 0.52 mol% Nb, 0.5 mol% Al, and a lithium-to-metal ratio of 1.03. 3. Heating: The mixture from step 2) was heated at 700°C under oxygen atmosphere for 12 hours, followed by grinding and sieving to obtain Comparative Example 2.1.

[0071] Positive electrode active material Comparative Example 2.2 was prepared according to the same method as Comparative Example 2.1, except that the heating temperature in step 3) was 720°C.

[0072] Positive electrode active material Comparative Example 2.3 was prepared according to the same method as Comparative Example 2.1, except that the heating temperature in step 3) was 740°C.

[0073] Example 2 Cathode active material Example 2.1 was prepared through a solid-state reaction between a lithium source and a precursor according to the following steps: 1. Preparation of Precursor D: 6 L of DI water, 350 mL of 220 g / L NH3(aq), and Ni with 5.0 µm D50 0.94 Mn 0.03 Co 0.03 The starting solution was prepared by adding 400 mL of a 440 g / L aqueous slurry containing (OH)2 seed particles to a 10 L reactor and adjusting the temperature in the reactor to 85 °C, which was maintained throughout the process. Next, a 120 g / L metal sulfate solution containing Ni, Mn, and Co (stoichiometric molar ratio of Ni:Mn:Co 94:03:03) was added to 220 g / L NH 3(aq) , and 230 g / L NaOH (aq) The solution was added and the temperature was approximately 30 kW / m for the first 6 hours. 3 The stirring power requirement for the remaining process steps is approximately 20 kW / m 3 The precipitation reaction was carried out by mixing at a stirring power of 0.5 μm / h. The feed rate of the metal sulfate solution was 540 mL / h at the start and continuously increased to maintain a constant particle growth rate of 0.5 μm / h. During the reaction, the feed rate of the NaOH solution was adjusted so that the pH value of the reaction mixture in the reactor was maintained at a constant 11.7 ± 0.1, and the feed rate of NH3(aq) was adjusted so that the NH3 concentration in the reaction mixture was maintained at a constant 12.0 ± 1 g / L. Reactor samples of the reaction mixture were taken every two hours, and the D50 values ​​were measured therefrom. The reaction was stopped when the D50 value of the reactor sample reached the target value of approximately 10.0 μm. The duration of the process was 11 hours. During the process, a portion of the liquid fraction of the reaction mixture was pumped out of the reactor using an external concentrator. The solid content of the reaction mixture in the reactor was approximately 180 g / L at the end of the process. The resulting aqueous slurry of metal hydroxides was filtered and diluted with 220 g / L of NaOH. (aq) The solution was washed with DI water at 60° C. The filter cake was dried in an oven at 120° C. for 12 hours to obtain Precursor D. 2. Mixing: Precursor D prepared from step 1) was mixed with LiOH, Nb2O5, and Al2O3 in an industrial blender to obtain a first mixture having 0.52 mol% Nb, 0.5 mol% Al, and a lithium-to-metal ratio of 1.03. 3. Heating: The mixture from step 2) was heated at 700°C under oxygen atmosphere for 12 hours, followed by grinding and sieving to obtain Example 2.1.

[0074] Positive electrode active material Example 2.2 was prepared according to the same method as Example 2.1, except that the heating temperature in step 3) was 720°C.

[0075] Positive electrode active material Example 2.3 was prepared according to the same method as Example 2.1, except that the heating temperature in step 3) was 740°C.

[0076] Comparative Example 3: Preparation of Precursor E 6 L DI water, 150 mL 220 g / L NH 3(aq) , and Ni0 with a D50 of 4.0 μm .65 Mn0 .15 Co 0.20 The starting solution was prepared by adding 500 mL of an 800 g / L aqueous slurry containing (OH)2 seed particles to a 10 L reactor, adjusting the temperature in the reactor to 65 °C, and maintaining this temperature throughout the process. 0.65 Mn 0.15 Co 0.20 A slurry of (OH)2 seed particles was prepared as described above.

[0077] Next, 120 g / L of a metal sulfate solution containing Ni, Mn, and Co (stoichiometric molar ratio of Ni:Mn:Co 65:15:20), 220 g / L of NH3(aq), and 230 g / L of NaOH solution were added, with a stirring power requirement of approximately 30 kW / m3 for the first 6 hours and approximately 20 kW / m3 for the remaining process steps. 3The precipitation reaction was carried out by mixing at a required stirring power of 10 ... 3(aq) The feed rate of 1000 to 10000 was adjusted. Reactor samples of the reaction mixture were taken every 2 hours, and the D50 was measured therefrom. The process was stopped when the D50 of the reactor sample reached the target value of approximately 10.2 μm, and the duration of the process was 28.5 hours. A concentrator was used to drain a portion of the liquid fraction of the reaction mixture from the reactor during the process. The solids content of the reaction mixture in the reactor vessel was approximately 700 g / L at the end of the process.

[0078] Example 3: Precursor F Preparation 6 L of DI water, 350 mL of 220 g / L NH3(aq), and Ni0 with a D50 of 4.0 μm .65 Mn0 .15 Co 0.20 The starting solution was prepared by adding 500 mL of an 800 g / L aqueous slurry containing (OH)2 seed particles to a 10 L reaction vessel, adjusting the temperature in the reaction vessel to 85 °C, and maintaining this temperature throughout the process.

[0079] Next, 120 g / L of a metal sulfate solution containing Ni, Mn, and Co (stoichiometric molar ratio of Ni:Mn:Co=65:15:20), 220 g / L of NH3(aq), and 230 g / L of NaOH solution were added, and the reaction was maintained at approximately 30 kW / m for the first 6 hours. 3 The stirring power requirement is approximately 20 kW / m for the remainder of the process. 3The precipitation reaction was carried out by mixing at a stirring power of 0.4 μm / h. The feed rate of the metal sulfate solution was 600 mL / h at the beginning and was continuously increased according to Equation 1 disclosed above to maintain a constant particle growth rate of 0.4 μm / h (i.e., G(t) = 0.4 μm / h). During the reaction, the feed rate of the NaOH solution was adjusted to stably maintain the pH value of the reaction mixture in the reaction vessel at 11.8 ± 0.1, and the NH3(aq) concentration in the reaction mixture was adjusted to stably maintain 12.0 ± 1 g / L. 3(aq) The feed rate of 1000 to 10000 was adjusted. Reactor samples of the reaction mixture were taken every 2 hours, and the D50 was measured therefrom. The reaction was stopped when the D50 of the reactor sample reached the target value of approximately 10.2 μm, and the duration of the process was 15 hours. A portion of the liquid fraction of the reaction mixture was pumped out of the reactor during the process by using a concentrator. The solids content of the reaction mixture in the reaction vessel, which was an aqueous slurry containing hydroxide particles, was approximately 780 g / L at the end of the process.

[0080] Ni 0.65 Mn 0.15 Co 0.20 Preparation of aqueous slurry containing (OH)2 seed particles A starting solution was prepared by adding 6 L of DI water, 55 mL of 220 g / L NH3(aq), and 300 mL of a 130 g / L aqueous slurry containing Ni(OH)2 seed particles with a D50 of 1.2 μm to a 10 L reaction vessel and adjusting the temperature in the reaction vessel to 85 °C and maintaining this temperature throughout the process.

[0081] Next, 120 g / L of a metal sulfate solution containing Ni, Mn, and Co (stoichiometric molar ratio of Ni:Mn:Co 65:15:20), 220 g / L of NH3(aq), and 230 g / L of NaOH solution were added, and the reaction was maintained at approximately 30 kW / m for the first 30 hours. 3 The stirring power requirement for the remaining process steps is approximately 20 kW / m 3The precipitation reaction was carried out by mixing at a required stirring power of 1000 kJ / L. The metal sulfate solution feed rate was 450 mL / h for the first 2 hours and 980 mL / h for the remaining process steps to maintain an average particle theoretical growth rate of 0.08 μm / h. During the reaction, NaOH solution was added to maintain the pH value of the reaction mixture in the reaction vessel at a constant 11.8 ± 0.1, and NH3(aq) was added to maintain the NH3(aq) concentration in the reaction mixture at 2-3 g / L. 3(aq) The feed rate of the reaction mixture was adjusted. Reactor samples of the reaction mixture were taken every 2 hours, and the D50 was measured therefrom. The process was stopped when the D50 of the reactor sample reached the target value of 4.0 μm, and the duration of the process was 36 hours. A concentrator was used to pump a portion of the liquid fraction of the reaction mixture out of the reactor during the process. The solid content of the reaction mixture in the reaction vessel was approximately 800 g / L at the end of the process.

[0082] Preparation of aqueous slurries containing Ni(OH)2 seed particles An initiating solution was prepared by adding 100 L of DI water and 1.0 L of 220 g / L aqueous ammonia solution (NH3(aq)) to a 200 L reactor, adjusting the reactor temperature to 55 °C, and maintaining this temperature throughout the process. A 5.5 M NaOH solution was added to adjust the pH value of the initiating solution in the reactor to 12.6-12.8.

[0083] Next, a 2 M NiSO solution with a feed rate of 30 L / h, 220 g / L NH(aq) with a feed rate of 0.52 L / h, and a 5.5 M NaOH solution were added successively in the reaction vessel. The solution was heated to approximately 35 kW / m 3 The mixture was mixed using a mixer with a stirring power of 1000 rpm, and the pH in the reactor was maintained at 12.6-12.8 by adding NaOH solution to establish and maintain the precipitation reaction, thereby preparing an aqueous slurry reaction mixture. 3(aq)The concentration was maintained at about 2 g / L. The reaction was carried out in a continuous mode. When the reaction reached a steady state about 30 hours after initiation, the reactant, i.e., NiOH, an aqueous slurry of nickel hydroxide with a D50 of 1.2 μm (i.e., seed particles), was collected from the overflow of the reaction vessel.

[0084] Dried products of the examples The reaction mixtures, i.e., aqueous slurries of metal hydroxides obtained in all of the examples, were filtered and washed with 220 g / L NaOH solution and DI water at 60°C. The filter cakes were dried in an oven at 120°C for 12 hours. Samples of each of precursors B, D, and F were subjected to ASTAR analysis, and the results are shown in Figure 4.

[0085] result [Table 2]

[0086] [Table 3]

[0087] Table 2 summarizes the precursor properties. Precursors B, D, and F exhibit significantly thicker primary particles compared to Precursors A, C, and E, as indicated by the p50 and p75 numbers. Precursors B, D, and F exhibit significantly smaller surface areas compared to Precursors A, C, and E. Each of Precursors A through D was lithiated into a cathode active material, the properties of which are summarized in Table 3.

[0088] Total base and water absorption represent undesirable surface impurities that cause problems during application of the positive electrode active material in an electrochemical cell, such as gelation during slurry formation and gassing during cycling.

[0089] The same observations as for Examples 2.1 to 2.3, which are positive electrode active materials having a Ni content of about 94 mol %, also apply to Comparative Examples 2.1 to 2.3.

Claims

1. A secondary particle-based powder material compound for preparing a positive electrode active material for a secondary battery, wherein the compound is an M-hydroxide or M-oxyhydroxide, and M contains one or more metal elements such as Ni, Co, and Mn. The secondary particles include a plurality of primary particles, When the compound is measured by laser diffraction, it has a median particle size D50 of 3.0 μm to 20.0 μm. The primary particles have a particle-based thickness distribution, which is measured by measuring the primary particle thickness of an image captured by an SEM, and the thickness distribution has a median thickness of 180 nm to 600 nm. The compound has a span value (D90-D10) / D50 with a maximum of 0.

6. The aforementioned compound is 4.0 m ２ / g or less and 1.5m ２ A compound having a specific surface area of ​​1 / g or more.

2. The compound according to claim 1, wherein the thickness distribution has corresponding thicknesses of 225 nm to 800 nm when the cumulative rate reaches 75%.

3. The compound according to any one of claims 1 to 2, having a tap density in the range of 1.5 to 2.5 g / cm³.

4. A compound according to any one of claims 1 to 3, Ni with content x, where x ≥ 30.0 mol%, and Mn with content y such that 0 ≤ y ≤ 70.0 mol%, and Co with content z, where 0 ≤ z ≤ 40.0 mol%, and includes, A compound in which x, y, and z are the molar contents of M, expressed as mol%, and x + y + z = 100.0 mol%.

5. The compound according to claim 4, wherein x ≥ 60 mol%, and / or y ≥ 20 mol%, and / or z ≤ 25 mol%.

6. The compound according to any one of claims 1 to 5, wherein the median particle size D50 is 4.0 μm to 15.0 μm.

7. The aforementioned compound is 3.6 m ２ / g or less, and 1.6m ２ A compound according to any one of claims 1 to 6, having a specific surface area of ​​1 / g or more.

8. A compound according to any one of claims 1 to 7, wherein the secondary particles have particle boundaries having an orientation difference angle distribution around the [0001] crystal axis, and a fraction of the particle boundary having an orientation difference angle of 55° to 65° determined by an automated crystal orientation map in TEM (F １ ) is the total fraction of the particle boundary having an orientation difference angle of 5° to 105° (F ２ A compound that is at least 10% based on ).

9. A method for producing a secondary particle-based powder material compound according to any one of claims 1 to 8, wherein the method is The process involves supplying a flow of a metal salt solution containing one or more metal elements to a reaction vessel for a certain period (T1 to T2), During the aforementioned period (T1 to T2), the metal salt solution was subjected to an aqueous solution containing one or more alkali hydroxides and an aqueous ammonia solution (NH₄). ３ The process involves mixing with (aq) to form an aqueous slurry containing hydroxide particles or oxyhydroxide particles of one or more metal elements, During the aforementioned period (T1 to T2), in the reaction vessel, A range of pH values ​​for the aqueous slurry, wherein the range is 11.6 or greater and 11.9 or less, and the pH value of the aqueous slurry is the pH value measured on a sample of the aqueous slurry after it has been cooled to 20°C. NH₂ 7.0 g / l or higher ３（ａｑ） The concentration of, and Maintain the temperature of the aqueous slurry at a minimum of 75°C and a maximum of 99°C. A method comprising further processing the aqueous slurry in the reaction vessel by separating the solid fraction from the liquid fraction after the completion of the aforementioned period (T2), and drying the solid fraction to obtain the secondary particle-based powder material compound.

10. The method according to claim 9, wherein during the aforementioned period (T1 to T2), the growth rate of the precipitated hydroxide in the reaction vessel is maintained at a maximum of 0.5 μm per hour.

11. The method according to claim 9 or 10, wherein, prior to the start of the period (T1), an aqueous slurry of seed particles is supplied into the reaction vessel, and the seeds in the seed slurry have a particle size distribution such that, when determined by laser diffraction, the median particle size D'50 is at least 0.10 μm and at most 3.0 μm.

12. The method according to claim 11, wherein the metal salt solution has a flow rate expressed as volume per unit time, and the instantaneous (t) flow rate is expressed by formula 1, [Math 1] where, m １ is the mass of the seed particles provided in the reaction vessel, G(t) is the growth rate of hydroxide particles or oxyhydroxide particles at instant t, where the value of G(t) is greater than 0, Δt is the period (T1 - T2), D'50 is the median particle size of the seed particles, M Ｍｅ is the molar mass of one or more metal elements, c Ｍｅ is the concentration of one or more metal elements, M ＭＥ（ＯＨ）２ is the molecular weight of the hydroxide or oxyhydroxide of one or more metal elements, method.

13. A method according to any one of claims 9 to 12, wherein the temperature of the aqueous slurry in the reaction vessel is at least 80°C and / or the temperature is at most 99°C and / or During the aforementioned period (T1 to T2), the NH ３（ａｑ） A method for maintaining a concentration of 9.0 g / l or higher.

14. A method according to any one of claims 9 to 13, wherein the one or more metal elements in the metal salt solution are Ni with content b, where b ≥ 30.0 mol%, and Mn with content c such that 0 ≤ c ≤ 70.0 mol%, and Co with a content of d, where 0 ≤ d ≤ 40.0 mol%, and includes Co, b, c, and d are the contents expressed in mol% relative to M, and b + c + d = 100 mol%, in this method.

15. A method for manufacturing a positive electrode active material, A mixture is obtained by mixing a powder material containing a secondary particle-based powder material compound according to any one of claims 1 to 8, a lithium donor, and optionally a dopant donor. The mixture is heated in an oxidizing atmosphere at a temperature of 650°C to 1000°C to obtain a positive electrode active material, and optionally, A method further comprising a heat treatment step of heating the powder material at a temperature of 105°C to 750°C before mixing.

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