Method for producing aqueous slurry and method for producing powdered hydroxides therefrom

Abstract

In general, the present invention relates to a metal hydroxide that can be used as a precursor of a cathode active material for a secondary battery and a method for manufacturing the same. In particular, but not exclusively, a method for preparing the same. The invention relates to a method for producing an aqueous slurry comprising hydroxides or oxyhydroxides of at least one or more metal elements, a method for producing powdered hydroxides or oxyhydroxides therefrom, and the use of the aqueous slurry or the powdered hydroxide or oxyhydroxide for manufacturing a positive electrode active material for a secondary battery.

Description

Technical Field

[0001] Generally speaking, the present invention relates to metal hydroxides which can be used as precursors for cathode active materials for secondary battery packs and methods for manufacturing the same. Specifically but not exclusively, the present invention relates to a method for manufacturing an aqueous slurry of a hydroxide or oxyhydroxide containing at least one or more metal elements, a method for manufacturing a powdery hydroxide or oxyhydroxide therefrom, and the use of the aqueous slurry or the powdery hydroxide or oxyhydroxide for manufacturing a positive electrode active material for a secondary battery pack. Background Art

[0002] Lithium-ion secondary battery packs generally include a negative electrode (anode), an electrolyte, and a positive electrode (cathode), and the positive electrode contains a lithium-transition metal oxide as an active material capable of intercalating and desorbing lithium. The lithium-transition metal oxide is usually manufactured from a transition metal hydroxide, oxide, or oxyhydroxide sequentially manufactured in a coprecipitation method, and the coprecipitation method discloses mixing a metal salt solution and an alkali solution in the presence of a complexing agent.

[0003] It is expected that the future lithium-ion battery pack market will be increasingly dominated by automotive applications. To be competitive, battery packs for automotive applications must be produced at the lowest possible cost. A large part of the cost comes from the active material, and the cost of the precursor is reflected in the cost of the active material. Providing these precursors by more efficient and / or less expensive methods, ideally without compromising their quality, can help reduce costs and increase the market acceptance of lithium-ion secondary battery packs.

[0004] In view of the above, there is a continuing need for further improvement in the method for manufacturing precursors. Summary of the Invention

[0005] The present invention aims to provide an improved method for preparing materials that can be directly / indirectly used subsequently as precursors for lithium-transition metal cathode materials for positive electrodes.

[0006] From a first aspect, the present invention can provide a method for manufacturing an aqueous slurry of hydroxide or oxyhydroxide particles comprising one or more elements, wherein the one or more elements include at least one of Ni, Co, and Mn. The hydroxide or oxyhydroxide particles can be used as a seed particle source in the precipitation process of a second hydroxide or oxyhydroxide, which in turn can ultimately be used as a precursor for a lithium transition metal cathode material for a positive electrode or as a precursor for a lithium transition metal cathode active material for a positive electrode. Such a method according to the present invention includes providing a volume of seed slurry V(1) into a reactor vessel having an effective volume V(2), wherein the seed slurry contains seeds with a median particle size d50 = D1, and the seed slurry has a seed solid content SG(1) expressed as the weight of seeds per volume of seed slurry, and subsequently includes:

[0007] - Supplying a stream of an aqueous metal salt solution containing the one or more elements to the reactor vessel during a period of time,

[0008] - During the period of time, mixing the metal salt solution with an aqueous solution containing one or more alkali metal hydroxides, thereby precipitating the hydroxide or oxyhydroxide of the one or more elements and forming an aqueous slurry containing hydroxide or oxyhydroxide particles of the one or more elements,

[0009] wherein the amount of seed slurry supplied is based on Formula 1:

[0010]

[0011] where SG(2) is the target solid content of the aqueous slurry expressed as weight per volume, and D2 is the target median particle size of the hydroxide or oxyhydroxide particles in μm.

[0012] The hydroxide or oxyhydroxide particles of one or more elements according to the present invention have a composition that can be represented by the general formula: Me-O x (OH) 2-x where 0 ≤ x ≤ 2, and Me includes at least one of Ni, Co, and Mn and possibly at least one other element such as impurities such as Na, S, etc.

[0013] The effective volume of the reactor vessel in this document means the maximum volume of the reaction mixture, i.e., the aqueous slurry, that can be loaded into the reactor vessel during the precipitation reaction / process.

[0014] The period of time can be expressed as T1 - T2, referring to the time course that starts at time T1, i.e., the start of the period of time, and ends at time T2, i.e., the end of the period of time.

[0015] According to the method of the present invention, the process is better controlled and predictable and can be easily customized according to the actual needs, such as the desired median particle size of hydroxide or oxyhydroxide particles. Additionally, according to this method, further nucleation is avoided. Further nucleation is less desirable because it may lead to the formation of small particles that tend to agglomerate, which in turn can change the production quality. Moreover, the hydroxide or oxyhydroxide particles produced according to this method have a uniformly distributed desired particle size.

[0016] Furthermore, the present invention enables the use of the same seed slurry source regardless of the desired target median size of the precipitated hydroxide or oxyhydroxide particles. Compared with known methods, it also enables better controllability and scalability of the precipitation process because in known methods, various trial and error attempts may be required to obtain a working process for achieving hydroxide or oxyhydroxide particles of the desired size. A further advantage compared with known methods is that it improves the per-reactor vessel efficiency of manufacturing plants for metal hydroxides used as cathode active materials because particles of the desired size can be obtained within a reasonable time without having to divide the reaction mixture into various reactor vessels.

[0017] Accordingly, the present invention provides an improved method for the precipitation process of metal hydroxides used as precursors for cathode active materials. The precipitation process generally may include supplying an aqueous metal salt solution, a neutralizing agent such as an alkali metal hydroxide, and a complexing agent such as an ammonium ion donor to a reaction vessel while stirring, and conducting a crystallization reaction.

[0018] According to the concept of the first aspect of the present invention, a second aspect of the present invention is also provided, which is a method for manufacturing powdery hydroxides or oxyhydroxides of one or more elements, wherein the method includes: I) providing an aqueous slurry according to the first aspect of the present invention, II) separating the hydroxide or oxyhydroxide particles from the liquid fraction of the aqueous slurry, and III) drying the separated hydroxide or oxyhydroxide particles.

[0019] A third aspect of the present invention is also provided, which is the use of the aqueous slurry according to the first aspect of the present invention or the powdery hydroxide or oxyhydroxide according to the second aspect of the present invention for manufacturing a positive electrode active material for a secondary battery pack.

[0020] A fourth aspect of the present invention is also provided, which is a method for manufacturing a positive electrode active material by using hydroxide or oxyhydroxide particles manufactured according to the first and second aspects of the present invention.

[0021] Various embodiments according to the present invention are disclosed in the claims and the specification. Unless otherwise explicitly stated, the embodiments and examples described in the claims and the specification can be freely combined with each other. Throughout the document, if any numerical range is provided, the range also includes the endpoint values unless otherwise explicitly stated. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] For further guidance, the drawings are included to better understand the teachings of the present invention, in which:

[0023] Figure 1 Scanning electron microscope (SEM) images of the particles obtained from Example 1 and Example 1.2 are shown. DETAILED DESCRIPTION

[0024] In the following detailed description, the preferred embodiments are described in detail so as to enable the practice of the present invention. Although the present invention is described with reference to these specific preferred embodiments, it should be understood that the present invention is not limited to these preferred embodiments. On the contrary, the present invention includes numerous alternatives, modifications, and equivalents, as will become apparent from considering the following detailed description and the drawings.

[0025] As used herein and in the claims, the term "comprising" should not be construed as limited to the manners listed thereafter; it does not exclude other elements or steps. It should be construed as specifying the presence of the stated features, integers, steps, or components, but does not exclude the presence or addition of one or more other features, integers, steps, or components or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to a composition consisting only of components A and B. This means that, for the purposes of the present invention, the only relevant components of the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0026] As used herein and in the claims, the term "positive electrode active material" (also referred to as cathode active material) is defined as a material that is electrochemically active in the positive electrode or cathode. The active material should be understood as a material that is capable of capturing and releasing Li ions when subjected to a voltage change over a predetermined period of time.

[0027] As used herein, the term "positive electrode" is defined as a material that contains a positive electrode active material in addition to other components that are not electrochemically active (in particular, conductive agents such as carbon black or binders such as PVDF).

[0028] As used herein, the term "NH 3(aq) concentration" and the like mean the concentration of ammonia in an aqueous solution.

[0029] In a first aspect, the present invention provides a method for manufacturing an aqueous slurry of hydroxide or oxyhydroxide particles comprising one or more elements, wherein the one or more elements include at least one of Ni, Co, and Mn. The hydroxide or oxyhydroxide particles can be used as a source of seed particles in the precipitation process of a second hydroxide or oxyhydroxide, which in turn can ultimately be used as a precursor for a lithium transition metal cathode material for a positive electrode or as a precursor for a lithium transition metal cathode active material for a positive electrode. Such a method according to the present invention includes providing a volume of seed slurry V(1) into a reactor vessel having an effective volume V(2), wherein the seed slurry contains seeds with a median particle size d50 = D1, and the seed slurry has a seed solid content SG(1) expressed as the weight of seeds per volume of seed slurry, and subsequently includes:

[0030] - During a time period T1 - T2, feeding a stream of an aqueous metal salt solution containing the one or more elements into the reactor vessel,

[0031] - During the time period T1 - T2, mixing the metal salt solution with an aqueous solution containing one or more alkali metal hydroxides, thereby precipitating the hydroxides of the one or more elements and forming an aqueous slurry containing hydroxide or oxyhydroxide particles of the one or more elements,

[0032] wherein the amount of the seed slurry fed is based on Formula 1:

[0033]

[0034] where SG(2) is the target solid content of the aqueous slurry expressed as weight per volume, and D2 is the target median particle size of the hydroxide or oxyhydroxide particles.

[0035] According to the method of the present invention, the precipitation process can be better controlled and scaled, more predictable, and can be easily customized according to actual needs.

[0036] During the manufacturing process, the precipitated hydroxide can be partially oxidized, depending on the atmosphere of the manufacturing process. Thus, the aqueous slurry may contain oxyhydroxide. It should be noted that the atmosphere conditions are not crucial for achieving the claimed invention.

[0037] In some embodiments, the pH of the aqueous slurry in the reactor vessel ranges from 11.5 to 12.2, and more preferably from 11.6 to 12.1, where the pH of the aqueous slurry is the pH measured on a sample of the aqueous slurry at 20 °C. In some embodiments, the pH value ranges from 10.5 to 12.0, preferably from 11.0 to 12.0, within which range, the nucleation process of new nuclei can be prevented while ensuring the growth of the precipitate particles present in the reactor vessel. As understood by those skilled in the art, the pH value can be measured by using a pH meter, such as a 780 Metrohm meter.

[0038] In some embodiments of the method according to the invention, it further comprises establishing or maintaining in the reactor vessel at least 1.0 g / l and preferably at most 13.0 g / l of NH 3(aq) concentration during the time period T1 - T2. Establishing or maintaining means that an aqueous solution of ammonia (NH 3(aq) ) can be provided as a starting solution in the reaction vessel before the start of the time period T1, and additionally or alternatively, an aqueous solution of ammonia (NH 3(aq) ) can be fed into the reaction vessel during the time period T1 - T2. An NH 3(aq) concentration below 1.0 g / l may cause nucleation. When the particle size of the hydroxide precipitated in the reactor is relatively small (e.g., less than 4 μm or less than 3 μm), a relatively high NH 3(aq) concentration, such as higher than 13.0 g / l, may cause agglomeration, and thus in such cases, preferably the concentration of NH 3(aq) is at least 1.5 g / l and at most 7 g / l, more preferably at least 1.5 g / l and at most 6 g / l, and most preferably at least 2 g / l and at most 4 g / l. On the other hand, when the particle size of the hydroxide precipitated in the reactor is relatively large (e.g., equal to or greater than 4 μm), the concentration of NH 3(aq) can be controlled at the higher end of the range between 1.0 g / l and 13.0 g / l; for example, the concentration of NH 3(aq) can be at least 7 g / l and at most 13.0 g / l, preferably at least 10 g / l and at most 12.0 g / l to allow for slower growth of the particle size (i.e., slower precipitation), which results in a denser particle structure. As understood by those skilled in the art, the NH3(aq) concentration can be measured by using a commercially available titrator such as a Metrhom 848 TitrinoPlus.

[0039] In some embodiments of the method according to the present invention, during the time period T1 - T2, the aqueous slurry in the reactor vessel has a temperature of at least 45°C and preferably at least 75°C, more preferably at least or equal to 85°C. A temperature below 45°C may result in a more porous structure of the precipitated hydroxide. In some embodiments, the temperature is at most 99°C, preferably at most 95°C, and more preferably at most 90°C. A temperature above 95°C may increase the difficulty of processability. When the temperature is at least 75°C, preferably at least or equal to 80°C, more preferably at least or equal to 85°C, the undesired cracking of hydroxide or oxyhydroxide particles can be prevented.

[0040] In some embodiments of the method according to the present invention, the aqueous slurry comprising hydroxide or oxyhydroxide particles of one or more elements has a liquid fraction and a solid fraction, wherein a part of the liquid fraction is removed from the reactor vessel during the time period, and wherein the solid fraction remains in the reactor vessel during the time period T1 - T2.

[0041] A narrow size distribution means the span value of the hydroxide or oxyhydroxide, expressed as (D90 - D10) / D50, which is generally in the range of < 0.8.

[0042] The means for removing a part of the liquid fraction (i.e., the mother liquor) of the aqueous slurry is not particularly limited. However, for example, a part of the liquid fraction can be removed by using a commercially available concentrator, which can be connected to the reactor vessel and is capable of selectively removing a part of the liquid from the reactor vessel.

[0043] In some embodiments, after the end of the time period (T2), the aqueous slurry in the reactor vessel comprising hydroxide or oxyhydroxide particles of one or more elements has a solid content of at least 600 g / l and preferably at least 750 g / l of the hydroxide or oxyhydroxide particles of one or more elements; preferably the solid content is the target solid content SG(2). By selecting the optimal, maximum target solid content, it may be possible to optimize the reaction flux. As will be understood by those skilled in the art, the target solid content can be selected taking into account the limitations of the reactor and mixing device used.

[0044] In some embodiments of the method according to the present invention, the mixing of the aqueous slurry with at most 40 kW / m 3 and preferably at most 35 kW / m 3 of the aqueous slurry can be carried out. A mixing energy greater than 40 kW / m3 may break the hydroxide or oxyhydroxide particles into smaller fragments. In some embodiments, the mixing energy is at least 5 kW / m 3 of the aqueous slurry, preferably at least 10 kW / m3 aqueous slurry. The disclosed mixing energy helps to obtain a homogeneous reaction mixture and avoid particle agglomeration.

[0045] In some embodiments, D1, the median particle size d50 of the seeds, is between at least 0.7 μm and at most 2.5 μm, and D2, the target median particle size D50, is at least 3.0 μm and at most 20 μm, preferably D2 is at most 10 μm, more preferably D2 is at most 7 μm.

[0046] In some embodiments, D1, the median particle size d50 of the seeds, is between at least 3.0 μm and at most 5 μm, and D2, the target median particle size D50, is at least 5.5 μm and at most 20 μm, preferably D2 is at most 15 μm, more preferably D2 is at most 13 μm.

[0047] The disclosed median particle size of the seeds and the target median particle size help to obtain excellent sphericity of the precipitated hydroxide or oxyhydroxide particles and maximize the reaction flux.

[0048] In some embodiments of the method according to the invention, the seeds are particles of a hydroxide or oxyhydroxide of at least one metal element, preferably the at least one metal element comprises at least Ni. According to the invention, the (multiple) metal elements for the seed particles and for the hydroxide or oxyhydroxide particles can be different, which provides further flexibility for implementing the method of the invention.

[0049] In some embodiments of the method according to the invention, the one or more elements in the hydroxide or oxyhydroxide particles include:

[0050] - Ni with a content of x, where 5.0 mol% ≤ 99 mol%,

[0051] - Co with a content of y, where 0 ≤ y ≤ 30.0 mol%, and

[0052] - Mn with a content of z, where 0 ≤ z ≤ 85.0 mol%,

[0053] - Al with a content of q, where 0 ≤ q ≤ 10.0 mol%, and

[0054] - one or more additional elements with a content of r, where the additional elements are elements from the list of B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, Si, Sr, Ti, Y, V, W, Zn, Na, S and Zr, where 0 ≤ r ≤ 5.0 mol%, and

[0055] wherein x, y, z, q, and r are contents expressed in mol% relative to the total molar content of said one or more elements in the hydroxide or oxyhydroxide particles, and wherein x + y + z + q + r = 100 mol%; preferably, wherein x ≥ 60.0 mol%, wherein z ≤ 30.0 mol%, and wherein (y + z) ≥ 1.0 mol%, more preferably, wherein x ≥ 70.0 mol%, and wherein preferably x ≥ 80.0 mol; or wherein z ≥ 50.0 mol%, and preferably wherein r ≤ 3.0 mol%; and / or wherein z ≥ 60.0 mol%; and / or wherein z ≤ 90.0 mol%, preferably wherein z ≤ 85.0 mol%. The values of x, y, z, q, r are measured by an inductively coupled plasma (ICP) method. It is understood that the expression ≥0 includes the absence of the element.

[0056] According to the present invention, there is also provided a method for manufacturing a powdery hydroxide or oxyhydroxide of one or more elements, wherein the method comprises: I) providing an aqueous slurry according to the method of the present invention described above, II) separating the hydroxide or oxyhydroxide particles from the liquid fraction of the aqueous slurry, and III) drying the separated hydroxide or oxyhydroxide particles.

[0057] During the manufacturing process, the hydroxide or oxyhydroxide particles from the aqueous slurry may be further partially oxidized.

[0058] For example, a precursor containing Ni, Co, and Mn in a molar ratio of x:y:z can be prepared in a mixed form by a precipitation reaction, and the steps are as follows: (1) providing a seed slurry, which can be completed by continuous precipitation, and then batch-precipitating mixed hydroxides in a reactor with NaOH and a mixed metal salt at a controlled pH as described above, (2) removing the precursor suspension and filtering, (3) drying the filtered wet cake. In step (1), the mixed salt can be a mixed sulfate, and the pH is generally between 11 and 12. Efficient precursor drying is usually carried out at a temperature above 100 °C for a certain time to remove most of the moisture. The typical moisture content after drying is less than 1 wt%, and can be measured by the well-known Karl Fischer titration method (ASTM D6869) at 250 °C. Before drying, the precursor has a pure or ideal hydroxide crystal structure (with the space group P-3m1).

[0059] In the method according to the present invention, the drying of the hydroxide precursor can be carefully carried out under well-defined conditions such as temperature, gas atmosphere and time, which can interact with each other. For example, a higher drying temperature requires less time to obtain the desired product, especially for large-scale production.

[0060] The dried hydroxide or hydroxyoxide particles according to the present invention, i.e., powdered hydroxide or hydroxyoxide, can be used to manufacture a positive electrode active material. The powdered hydroxide or hydroxyoxide can be mixed with a lithium source to obtain a mixture. The mixture is sintered at a temperature between 650 °C and 1000 °C. Optionally, a heat treatment can be carried out at a temperature between 105 °C and 750 °C before mixing.

[0061] Accordingly, the present invention also relates to an aqueous slurry containing hydroxide or hydroxyoxide particles obtainable by the method according to the first aspect of the present invention and the use of the powdered hydroxide or hydroxyoxide obtainable by the second aspect of the present invention for manufacturing a positive electrode active material for a secondary battery pack.

[0062] Examples

[0063] pH analysis

[0064] The pH value of the sample was measured with a 780 Metrohm meter calibrated with pH 7 and pH 13 standards. The sample was cooled to 20 °C, and the pH was measured from the sample by lowering the pH electrode into the sample and waiting for the pH reading to stabilize.

[0065] NH 3(aq) Concentration analysis

[0066] The concentration of NH 3(aq) in the reactor sample was measured by end-point titration using a Metrhom 848 Titrino Plus instrument. One milliliter of the sample solution was added to the titration vessel. 30 - 40 ml of deionized water and 1 ml of 1M NaOH were added. The sample was titrated to the end point with 0.1M HCl.

[0067] Solid content analysis

[0068] To determine the solid content of the hydroxide precipitated in the aqueous slurry, a sample taken from the aqueous slurry (the "reaction mixture" in the examples) was thoroughly mixed, and 10 - 30 ml of the mixed sample was pipetted onto a filter paper and then filtered onto a washed and weighed 0.8 µm membrane. The filtered membrane was rinsed with DI water, then dried and the weight of the dried membrane was measured, from which the solid content was calculated and expressed as the weight of dried hydroxide per liter of aqueous slurry (g / l).

[0069] Particle Size Distribution (PSD) Analysis

[0070] After dispersing the particles of the sample in an aqueous medium, the PSD was measured using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion unit. To improve the dispersion of the metal hydroxide powder, sufficient ultrasonic irradiation and stirring were applied, and a suitable surfactant was introduced. The percentile values D10, D50, and D90 are the particle diameter values at 10%, 50%, and 90% respectively in the cumulative distribution. The span value of the hydroxide is the value of (D90 - D10) / D50.

[0071] Example 1

[0072] Example 1.1

[0073] An initial solution was prepared by placing 6 L of DI water, 55 mL of 220 g / L NH3(aq), and 1.56 L of a seed slurry containing Ni(OH)2 seeds with a D50 of 1.2 µm and a solid content of 130 g / L in a reactor vessel with an effective volume of 8.75 L, adjusting the temperature in the reactor vessel to 85 °C and maintaining it at this temperature throughout the process. The volume of the seed slurry was calculated using Equation 1 below, with a target solid content of 800 g / L and a target median particle size D50 of 3.9 μm.

[0074] Equation 1:

[0075]

[0076] Where V(1) is the volume of the seed slurry, V(2) is the effective volume of the reactor vessel, SG(2) is the target solid content of the aqueous slurry, D1 is the median seed particle size d50, SG(1) is the solid content of the seed slurry, and D2 is the target median particle size D50.

[0077] Next, a metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of Ni:Mn:Co = 65:15:20) at 120 g / L, 220 g / L NH3(aq), and 230 g / L NaOH solution were added, and while mixing at a power density of about 30 kW / m for the first 30 hours and at 20 kW / m for the remainder of the process 3 or so and at 20 kW / m for the remainder of the process 3Precipitation reaction is carried out by mixing power densities of around [value]. The feeding rate of the metal sulfate solution is 450 mL / h in the first two hours and 980 mL / h for the rest of the process. During the reaction, NaOH solution is added to keep the pH value of the reaction mixture in the reactor vessel stable at 11.8 ± 0.1, and the feeding rate of NH3(aq) is adjusted so that the NH 3(aq) concentration of the reaction mixture is maintained at 2 to 3 g / L. Reactor samples of the reaction mixture are taken every two hours and D50 is measured therefrom. When the D50 of the reactor sample reaches the target value of 3.9 µm, the process is stopped, and the duration of this process is 36 hours. During this process, a part of the liquid fraction of the reaction mixture is pumped out of the reactor using a concentrator, and the solid content of the reaction mixture in the reactor vessel at the end of the process (which is an aqueous slurry containing hydroxide particles) is around the target solid content of 800 g / L.

[0078] The reaction mixture from Example 1.1 can then be dried or can be used as a seed source for further precipitation, for example as described in Example 1.2.

[0079] Example 1.2

[0080] An initial solution is prepared by placing 6 L of DI water, 350 mL of 220 g / L NH3(aq), and 515 mL of an 800 g / L seed slurry containing Ni 65 Mn 15 Co 20 (OH)2 seed particles in a reactor vessel with an effective volume of 8.75 L, adjusting the temperature in the reactor vessel to 85°C and maintaining it at this temperature throughout the process. The volume of the seed slurry is calculated using Equation 1 above, with a target solid content of 780 g / L and a target median particle size D50 of 10.2 µm.

[0081] Next, a precipitation reaction is carried out by adding a metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of Ni:Mn:Co of 65:15:20) at 120 g / L, 220 g / L NH3(aq), and 230 g / L NaOH solution, and simultaneously mixing at a power density of around 30 kW / m 3 for the first 6 hours and around 20 kW / m 3 for the rest of the process. The feeding rate of the metal sulfate solution is 600 mL / h at the start and continuously increases according to Equation 2 below (to 3700 mL / h at the end of the process) to keep the particle growth rate constant at 0.4 µm / h.

[0082] Equation 2:

[0083]

[0084] Where m1 is the mass (grams) of the seed particles provided in the reactor vessel, G(t) is the hydroxide particle growth rate at time t, where the value of G(t) is non-zero, ∆t is the time period T1 - T2, D’50 is the median particle size of the seed particles in μm, and M Me is the molar mass (grams / mole) of the one or more elements, c Me is the concentration (grams / L) of the one or more elements, and M Me(OH)2 is the molecular weight (grams / mole) of the hydroxide of the one or more elements.

[0085] During the reaction, the feed rate of the NaOH solution is adjusted so that the pH value of the reaction mixture in the reactor vessel is kept stable at 11.8 ± 0.1, and the feed rate of NH3(aq) is adjusted so that the NH 3(aq) concentration in the reaction mixture is kept stable at 12.0 ± 1 g / L. Reactor samples of the reaction mixture are taken every two hours and D50 is measured therefrom. When the D50 of the reactor sample reaches approximately the target value of 10.2 µm, the process is stopped, and the duration of this process is 15 hours. During this process, a part of the liquid fraction of the reaction mixture is pumped out of the reactor using a concentrator, and the solid content of the reaction mixture (which is an aqueous slurry containing hydroxide particles) in the reactor vessel at the end of the process is about the target solid content of 780 g / L.

[0086] Example 2

[0087] Example 2.1

[0088] An initial solution is prepared by placing 6 L of DI water, 55 mL of 220 g / L NH3(aq), and 410 mL of an aqueous slurry containing NiOH2 seed particles with a D50 of 1.2 µm and a concentration of 130 g / L in a reactor vessel with an effective volume of 8.75 L, adjusting the temperature in the reactor vessel to 85°C and maintaining it at this temperature throughout the process. The volume of the seed slurry is calculated using Equation 1 above, with a target solid content of 440 g / L and a target median particle size D50 of 5.0 μm.

[0089] Next, by adding a metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of Ni:Mn:Co of 94:03:03) at 120 g / L, 220 g / L NH3(aq), and 230 g / L NaOH solution, and simultaneously at 33 kW / m for the first 30 hours3 The power densities around are mixed and the precipitation reaction is carried out at a power density of about 30 kW / m 3 around for the remaining time of the process. The feed rate of the metal sulfate solution is 450 mL / h in the first two hours and 980 mL / h for the remaining time of the process. During the reaction, NaOH solution is added to keep the pH value of the reaction mixture in the reactor vessel stable at 11.8 ± 0.2, and the feed rate of NH3(aq) is adjusted so that the NH3 (aq) concentration of the reaction mixture is maintained at 2 to 3 g / L. Reactor samples of the reaction mixture are taken every two hours and D50 is measured therefrom. When the D50 of the reactor sample reaches the target value of 5.0 µm, the process is stopped, and the duration of the process is 48 hours. During this process, a part of the liquid fraction of the reaction mixture is pumped out from the reactor, and the solid content of the reaction mixture (aqueous slurry containing hydroxide particles) in the reactor vessel at the end of the process is about the target solid content of 440 g / L.

[0090] The reaction mixture from Example 2.1 can then be dried or can be used as a seed source for further precipitation, such as as described in Example 2.2.

[0091] Example 2.2

[0092] An initial solution is prepared by adding 6 L of DI water, 350 mL of 220 g / L NH3(aq), and 447 mL of 440 g / L aqueous slurry of Ni 94 Mn 03 Co 03 (OH)2 seed particles with a D50 of 5.0 µm to a reactor vessel with an effective volume of 8.75 L, adjusting the temperature in the reactor vessel to 85 °C and maintaining it at this temperature throughout the process. The volume of the seed slurry is calculated using Equation 1 above, with a target solid content of 180 g / L and a target median particle size D50 of 10.0 µm.

[0093] Next, by adding a metal sulfate solution containing Ni, Mn, and Co (in a stoichiometric molar ratio of Ni:Mn:Co of 94:03:03) at 120 g / L, 220 g / L NH3(aq), and 230 g / L NaOH solution, while mixing at a power density of about 30 kW / m in the first 6 hours 3 and at a power density of 20 kW / m for the remaining time of the process 3Precipitation reaction is carried out by mixing power densities of about. The feed rate of the metal sulfate solution is 540 mL / h at the beginning and continuously increases according to Equation 2 above to keep the particle growth rate constant at 0.5 μm / h. During the reaction, the feed rate of the NaOH solution is adjusted so that the pH value of the reaction mixture in the reactor vessel is kept stable at 11.7 ± 0.1, and the feed rate of NH3(aq) is adjusted so that the NH 3(aq) concentration in the reaction mixture is kept stable at 12.0 ± 1 g / L. Reactor samples of the reaction mixture are taken every two hours and D50 is measured therefrom. When the D50 of the reactor sample reaches the target value of about 10.0 µm, the process is stopped, and the duration of this process is 11 hours. During this process, a part of the liquid fraction of the reaction mixture is pumped out from the reactor, and the solid content of the reaction mixture in the reactor vessel at the end of the process is about the target solid content of 180 g / L.

Claims

1. A method for manufacturing an aqueous slurry of hydroxide or oxyhydroxide particles comprising one or more elements, wherein the one or more elements include at least one of Ni, Co, and Mn, wherein the method comprises feeding a volume of seed slurry V(1) into a reactor vessel having an effective volume V(2), wherein the seed slurry contains seeds with a median particle size d50 = D1, and the seed slurry has a solids content SG(1) expressed as the weight of seeds per volume of the seed slurry, wherein the method then comprises: - During a time period (T1 - T2), feeding a stream of an aqueous metal salt solution containing the one or more elements into the reactor vessel, - During the time period (T1 - T2), mixing the metal salt solution with an aqueous solution containing one or more alkali metal hydroxides to form the aqueous slurry containing hydroxide or oxyhydroxide particles of the one or more elements, wherein the feeding of the seed slurry is based on Formula 1: where SG(2) is the target solids content of the aqueous slurry expressed as the weight of hydroxide or oxyhydroxide particles per volume of the aqueous slurry, and D2 is the target median particle size D50 of the hydroxide or oxyhydroxide particles in μm.

2. The method according to claim 1, wherein the pH value of the aqueous slurry in the reactor vessel ranges between 11.5 and 12.2, and more preferably between 11.6 and 12.1, wherein the pH of the aqueous slurry is the pH measured for a sample of the aqueous slurry at 20°C.

3. The method according to any one of the preceding claims, the method further comprising supplying an aqueous solution of ammonia, namely aqueous ammonia solution (NH 3(aq) ), wherein the concentration of NH 3(aq) in the aqueous slurry in the reactor vessel is at least 1.0 g / l and preferably at most 13.0 g / l.

4. The method according to any one of the preceding claims, wherein during the time period (T1 - T2), the aqueous slurry containing hydroxide or oxyhydroxide particles of the one or more elements in the reactor vessel has a temperature of at least 45°C and preferably at least 75°C, more preferably at least or equal to 85°C and at most 99°C, preferably at most 95°C and more preferably at most 90°C.

5. The method according to any one of the preceding claims, wherein the aqueous slurry containing hydroxide or oxyhydroxide particles of the one or more elements has a liquid fraction and a solid fraction, wherein a part of the liquid fraction is removed from the reactor vessel during the time period (T1 - T2), and wherein the solid fraction is retained in the reactor vessel during the time period (T1 - T2).

6. The method according to any one of the preceding claims, wherein after the end of the time period (T2), the aqueous slurry containing hydroxide or oxyhydroxide particles of the one or more elements in the reactor vessel has a solids content of at least 600 g / l and preferably at least 750 g / l of the hydroxide or oxyhydroxide particles of the one or more elements; preferably the solids content is the target solids content SG(2).

7. The method according to any one of the preceding claims, wherein the mixing is carried out with the aqueous slurry at up to 40 kW / m 3 and preferably at up to 35 kW / m 3 of the aqueous slurry.

8. The method according to any one of the preceding claims, wherein D1, i.e., the median particle size d50 of the seeds, is in the range of at least 0.7 μm and at most 2.5 μm, and D2, i.e., the target median particle size D50, is at least 3.0 μm and at most 20 μm, preferably D2 is at most 10 μm, more preferably D2 is at most 7 μm.

9. The method according to any one of claims 1 to 7, wherein D1, i.e., the median particle size d50 of the seeds, is in the range of at least 3.0 μm and at most 5 μm, and D2, i.e., the target median particle size D50, is at least 5.5 μm and at most 20 μm, preferably D2 is at most 15 μm, more preferably D2 is at most 13 μm.

10. The method according to any one of the preceding claims, wherein the seeds are particles of a hydroxide or oxyhydroxide of at least one metal element, preferably the at least one metal element comprises at least Ni.

11. The method according to any one of the preceding claims, wherein the one or more elements in the hydroxide or oxyhydroxide particles comprise: - Ni in an amount x, where 5.0 mol% ≤ x ≤ 99 mol%, - Co in an amount y, where 0 ≤ y ≤ 30.0 mol%, and - Mn in an amount z, where 0 ≤ z ≤ 85.0 mol%, - Al in an amount q, where 0 ≤ q ≤ 10.0 mol%, and - one or more additional elements in an amount r, where the additional elements are elements from the list of B, Ba, Ca, Ce, Cr, Fe, La, Mg, Mo, Nb, Si, Sr, Ti, Y, V, W, Zn, Na, S, and Zr, where 0 ≤ r ≤ 5.0 mol%, and where x, y, z, q, and r are contents expressed in mol% relative to the total molar content of the one or more elements in the hydroxide or oxyhydroxide particles, and where x + y + z + q + r = 100 mol%.

12. A method for manufacturing a powdery hydroxide or oxyhydroxide of one or more elements, wherein the method comprises: I) manufacturing an aqueous slurry comprising hydroxide or oxyhydroxide particles of one or more elements according to any one of the preceding claims, II) separating the hydroxide or oxyhydroxide particles from the liquid fraction of the aqueous slurry, and III) drying the separated hydroxide or oxyhydroxide particles.

13. A method for manufacturing a positive electrode active material, the method comprising: 1) manufacturing a powdery hydroxide or oxyhydroxide of one or more elements according to claim 12; 2) mixing the powdery hydroxide or oxyhydroxide with a lithium source to obtain a mixture; and 3) sintering the mixture at a temperature between 650 °C and 1000 °C.

14. Use of an aqueous slurry of hydroxide or oxyhydroxide particles containing one or more elements obtained by the method according to any one of claims 1 to 11, or a powdery hydroxide or oxyhydroxide of one or more metal elements obtained according to claim 12, for manufacturing a positive electrode active material for a secondary battery pack.

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