Method for producing particulate (oxy)hydroxide

Abstract

1. A method for producing particulate (oxy)hydroxide of TM containing nickel, comprising the steps of: (a) an aqueous solution (α) containing a water-soluble salt of Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta; and an aqueous solution (β) containing an alkali metal hydroxide; and optionally an aqueous solution containing ammonia (γ) providing (b) combining solution (α) with solution (β) and, if applicable, solution (γ) in a stirred tank reactor at a pH value in the range of 12.0 to 13.0, thereby producing solid particles of nickel-containing hydroxide and slurrying the solid particles; (c) transferring the slurry to another stirred tank reactor and combining it with solution (α), solution (β), and, if applicable, solution (γ), at a pH value in the range of 11.0 to 12.7, under conditions in which the solubility of nickel is higher than in step (b); Including, The stirring speed is reduced during step (c).

Description

[Technical Field]

[0001] The present invention relates to a method for producing a particulate (oxy)hydroxide of TM, wherein the TM comprises nickel, and the method comprises the steps of: (a) providing an aqueous solution (α) containing a water-soluble salt of Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, an aqueous solution (β) containing an alkali metal hydroxide, and optionally an aqueous solution (γ) containing ammonia; (b) combining solution (α) with solution (β) and, if applicable, solution (γ) in a stirred tank reactor at a pH value in the range of 12.0 to 13.0, thereby producing solid particles of nickel-containing hydroxide and slurrying the solid particles; (c) transferring at least a portion of the slurry obtained in step (b) to another stirred tank reactor and combining it with solution (α), solution (β), and, if applicable, solution (γ), at a pH value in the range of 11.0 to 12.7 under conditions in which the solubility of nickel is higher than in step (b); Including, The stirring speed is reduced during step (c). [Background technology]

[0002] Lithiated transition metal oxides are currently used as electrode active materials in lithium-ion batteries. Extensive research and development work has been conducted over the past few years to improve properties such as charge density and specific energy, as well as other properties such as reduced cycle life and capacity loss, which can adversely affect the life or applicability of lithium-ion batteries. Further efforts are being made to improve manufacturing methods.

[0003] A typical method for making cathode materials for lithium-ion batteries involves first forming a so-called precursor by co-precipitating a transition metal as a carbonate, oxide, or preferably as a hydroxide (e.g., oxyhydroxide), which may or may not be basic. This precursor is then mixed with a lithium source, such as, but not limited to, LiOH, Li2O, or Li2CO3, and calcined (combusted) at high temperatures. The lithium salt(s) can be used as hydrate(s) or in a dehydrated form. The calcination, or combustion, of the precursor, often referred to as thermal treatment or heat treatment, is typically carried out at temperatures ranging from 600 to 1,000°C. During the thermal treatment, a solid-state reaction occurs and the electrode active material is formed. The thermal treatment is carried out in the heated zone of an oven or kiln.

[0004] A typical type of cathode active material that provides high energy density contains a large amount of Ni (Ni-rich), for example, at least 80 mol % relative to the non-lithium metal content, but the energy density still needs improvement.

[0005] To a large extent, the properties of the precursor are translated to some extent into the properties of the respective electrode active material, such as particle size distribution, respective transition metal content, etc. Therefore, by manipulating the properties of the precursor, it is possible to influence the properties of the electrode active material. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, an object of the present invention is to provide a precursor of an electrode active material with high energy density and a simple method for producing the same. [Means for solving the problem]

[0007] Thus, a process as defined at the beginning has been found, hereinafter also referred to as the process of the invention or the process according to the invention. The process of the invention is a process for producing particulate (oxy)hydroxide of TM, which also functions as a precursor of the electrode active material and is therefore also referred to as precursor. [Brief explanation of the drawings]

[0008] [Figure 1] Figure 1 shows an SEM image of pCAM.3. [Figure 2] Figure 2 shows an SEM image of pCAM.3. DETAILED DESCRIPTION OF THE INVENTION

[0009] In one embodiment of the present invention, the resulting precursor is composed of secondary particles that are aggregates of primary particles.

[0010] In one embodiment of the present invention, the specific surface area (BET) of the obtained precursor is between 2 and 10 m, determined by nitrogen adsorption, for example according to DIN-ISO 9277:2003-05. 2 / g range.

[0011] The precursor is an (oxy)hydroxide of TM, which comprises Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta.

[0012] In one embodiment of the present invention, TM is of general formula (I) (Ni a Co b Mn c ) 1-d M d (I) It is a combination of metals by During the ceremony, a is in the range of 0.6 to 0.95, preferably 0.8 to 0.92; b is in the range of 0.025 to 0.2, preferably 0.025 to 0.15; c is in the range of 0 to 0.2, preferably 0 to 0.15, and d is in the range of 0 to 0.1, preferably 0 to 0.05; M is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, and Ta; a+b+c=1 is.

[0013] The TM may contain trace amounts of additional metal ions as impurities, such as trace amounts of ubiquitous metals such as sodium, calcium, or zinc, but such trace amounts are not considered within the context of this invention. Trace amounts in this context mean amounts of 0.05 mol % or less, based on the total metal content of the TM.

[0014] The method of the present invention comprises the following steps (a), (b) and (c), hereinafter referred to as steps (a), (b) and (c), respectively, or simply as (a) or (b) or (c). The method of the present invention is described in detail below.

[0015] Step (a) comprises providing an aqueous solution (α) containing a water-soluble salt of Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, an aqueous solution (β) containing an alkali metal hydroxide, and optionally an aqueous solution (γ) containing ammonia.

[0016] The term water-soluble salts of cobalt and nickel or manganese, or water-soluble salts of metals other than nickel, cobalt and manganese, refers to salts that have a solubility of 25 g / l or more in distilled water at 25° C., the amount of salt being determined excluding water of crystallization and water from aquo complexes. The water-soluble salts of nickel, cobalt and manganese are preferably those of Ni 2+ and Co 2+ and Mn 2+Examples of water-soluble salts of nickel and cobalt are sulfates, nitrates, acetates and halides, especially chlorides. Nitrates and sulfates are preferred, with sulfates being more preferred.

[0017] Said aqueous solution (α) preferably contains Ni and the further metal(s) in the relative concentrations intended for the TM of the precursor.

[0018] The pH of solution(s) (α) ranges from 2 to 5. In embodiments where a higher pH value is desired, ammonia may be added to solution (α). However, it is preferred not to add ammonia to solution (α).

[0019] In one embodiment of the present invention, one solution (α) is provided.

[0020] In another embodiment of the present invention, at least two different solutions (α) are provided, e.g., solution (α1) and solution (α2), which differ in the relative amount of water-soluble salt of a metal. In one embodiment of the present invention, solution (α1) and solution (α2) are provided, with the relative amount of nickel being higher in solution (α1) than in solution (α2), e.g., due to Mn or Co.

[0021] Step (a) further provides an aqueous solution of an alkali metal hydroxide, hereinafter also referred to as solution (β). Examples of alkali metal hydroxides include lithium hydroxide, potassium hydroxide, and a combination of sodium hydroxide and potassium hydroxide, with sodium hydroxide being even more preferred.

[0022] Solution (β) contains a certain amount, for example 0.1 to 2% by weight, of carbonate, relative to the respective amount of alkali metal hydroxide, either intentionally added or due to aging of the solution or the respective alkali metal hydroxide.

[0023] The solution (β) has a hydroxide concentration in the range of 0.1 to 12 mol / l, preferably 6 to 10 mol / l.

[0024] The pH value of the solution (β) is preferably 13 or higher, for example 14.5.

[0025] In the process of the present invention, it is preferred to use ammonia, but this is preferably fed separately as solution (γ) or solution (β), and not fed to solution (α).

[0026] In one embodiment of the present invention, the following steps (b) and (c) are carried out at a temperature in the range of 10 to 85° C., preferably in the range of 20 to 60° C. Preferably, steps (b) and (c) are carried out at the same temperature.

[0027] In the context of the method of the present invention, the pH value refers to the pH value of the respective solution or slurry at 23°C.

[0028] In one embodiment of the present invention, steps (b) and (c) are carried out at the same pressure, for example ambient pressure.

[0029] Steps (b) and (c) are preferably carried out in at least two stirred tank reactors, for example in a cascade of two or three stirred tank reactors.

[0030] Step (b) comprises combining solution (α), solution (β), and, if applicable, solution (γ) in a stirred tank reactor at a pH value in the range of 12.0 to 13.0, thereby producing solid particles of nickel-containing hydroxide, and then slurrying the solid particles. Thus, a slurry is obtained.

[0031] In one embodiment of the present invention, step (b) has a duration in the range of rt·0.03 to rt·1.0, preferably either rt·0.03 to rt·0.2 or rt·0.8 to rt·1.0, where rt is the average reaction time of steps (b) to (e) or the average residence time of the reaction system in which steps (b) and (c) are carried out.

[0032] In one embodiment of the present invention, stirring during step (b) is carried out at a rate that provides a moderate dissipation rate in the range of 0.1 W / kg to 7 W / kg, preferably 0.5 W / kg to 5 W / kg. For example, for a 3.2 liter stirred tank reactor, a typical stirring rate is in the range of 400 rpm to 1000 rpm (revolutions per minute).

[0033] In step (b), a slurry is obtained.

[0034] Step (c) involves transferring at least a portion of the slurry obtained in step (b) to another stirred tank reactor and combining it with solution (α), solution (β), and, if applicable, solution (γ), at a pH value in the range of 11.0 to 12.7 under conditions in which the solubility of nickel is higher than in step (b).

[0035] Transferring at least a portion of the slurry obtained in step (b) means that at least some of the solids and at least some of the continuous phase of the slurry, i.e., the mother liquor, are transferred to another stirred tank reactor, which may or may not have the same solids to continuous phase ratio as obtained in step (b).

[0036] In a particular embodiment of step (c), the entire slurry produced during step (b) is transferred to another stirred tank reactor. In another embodiment, a portion of the slurry obtained in step (b), for example, 10 to 50% by volume, is transferred.

[0037] In this context, "nickel solubility" refers to the solubility of Ni 2+ This refers to the solubility of the salt. In the present invention, the solubility of nickel in step (c) is in the range of 0.01 ppm to 500 ppm, preferably 1 to 300 ppm. The solubility can be measured by separating the liquid from the solid phase by filtration, and then determining the concentration of nickel ions in the solution by ICP-OES analysis or inductively coupled plasma atomic emission spectrometry.

[0038] In the context of step (c), the solubility of nickel is increased, for example, by lowering the pH value or by increasing the concentration of a complexing agent, for example ammonia.

[0039] In one embodiment of the present invention, the solubility of nickel in step (c) is increased by 10 to 50,000 times, preferably 100 to 8,000 times, compared to step (b).

[0040] In one embodiment of the present invention, the pH value in step (c) is at least 0.2 lower than in step (b), for example, 0.3 to 0.7 lower. For example, if the pH value during step (b) is exactly 12.0, the pH value in step (c) is selected in the range of 9.0 to 11.8. The change in pH value can be achieved, for example, by slowing down the addition rate of solution (β), or by increasing the addition rate of solution (α), or by reducing the amount of ammonia, or by a combination of at least two of the above measures. It is also possible to modify solution (β) by introducing a solution of alkali metal hydroxide with a lower concentration.

[0041] In another embodiment of the present invention, the concentration of the complexing agent, e.g., ammonia, in step (c) is higher than in step (b). A higher concentration of complexing agent is achieved by adding more complexing agent or more ammonia. The addition or more ammonia may be achieved by adding solution (γ) in step (c) rather than in step (b), or by adding a more concentrated solution (γ) in step (c) than in step (b), or by adding more solution (γ) per time unit in step (c) than in step (b). It is preferred to add more solution (γ) per time unit in step (c) than in step (b).

[0042] In one embodiment of the present invention, the ammonia concentration in the slurry is higher than in step (b).

[0043] In the step (c), the stirring speed is reduced, for example, by 0.25 to 0.75 times, preferably 0.25 to 0.5 times. In one embodiment of the present invention, the stirring speed in step (c) is decreased continuously, for example linearly.

[0044] In one embodiment of the present invention, the stirring speed in step (c) is reduced stepwise, for example in one step or in 2 to 10 steps.

[0045] In one embodiment of the present invention, the stirring speed at the start of step (c) is the same as or lower than step (b). In this context, "lower than step (b)" refers to the stirring speed at the end of step (b).

[0046] In one embodiment of the invention, solution (α) used in step (b) has a different composition compared to solution (α) used in step (c), e.g., the nickel content of solution (α) used in step (c) is lower than the nickel content of solution (α) used in step (b). In another embodiment, solution (α) used in step (b) has the same composition as solution (α) used in step (c).

[0047] In one embodiment of the present invention, steps (b) and (c) are carried out under an inert gas, for example a noble gas such as argon, or under N2.

[0048] In one embodiment of the present invention, a slight total excess of hydroxide is applied, for example 0.1-10 mol % relative to TM.

[0049] In one embodiment of the invention, mother liquor is removed from the slurry during at least one of steps (b) and (c), for example by a clarifier, preferably in step (c). In another embodiment, mother liquor is not removed during either step (b) or (c).

[0050] In one embodiment of the present invention, the addition rate of solutions (α) and (β) is increased, for example, by 1.5 to 20 times, preferably 3 to 10 times, in liters per hour, during step (c).

[0051] In one embodiment of the present invention, the mean diameter (D50) of the particles grows linearly with the cube root of the solids content (in g / L), as measured by dynamic light scattering.

[0052] By carrying out the method of the present invention, a precursor of an electrode active material with high energy density can be obtained.

[0053] A further aspect of the present invention relates to a particulate mixed metal (oxy)hydroxide, hereinafter also referred to as the precursor of the present invention. The precursor of the present invention is useful for producing a high-energy-density electrode active material (e.g., 600 to 950 W·h / kg, preferably 800 to 950 W·h / kg) by converting it with a lithium source. The precursor of the present invention is produced by the method of the present invention.

[0054] The precursor of the present invention is a particulate material. In one embodiment of the present invention, the precursor of the present invention has an average particle size D50 in the range of 3 to 20 μm, preferably 5 to 16 μm. The average particle size is determined, for example, by light scattering, laser diffraction, or electroacoustic spectroscopy. The particles are composed of aggregates of primary particles, and the above particle size refers to the secondary particle size.

[0055] The secondary particles of the precursor of the present invention may be considered core-shell particles, with the primary particles being primarily randomly oriented in the core and primarily radially oriented in the shell, and the metal composition of the core and shell is preferably the same.

[0056] In one embodiment of the present invention, particularly when produced by a batch process, the precursor of the present invention comprises Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, wherein the primary particles have a predominantly radial orientation within the shell and the secondary particles have a product of span and form factor in the range of 0.3 to 0.6 and a ratio of secondary particle size to core diameter of less than 7.5.

[0057] In another embodiment of the invention, particularly when produced by a continuous process, the precursor of the invention comprises Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, wherein the primary particles have a predominantly radial orientation within the shell, and the particles have a product of span and form factor in the range of 0.8 to 1.4 and a ratio of secondary particle size to core diameter in the range of 1.2 to 1.6.

[0058] The form factor is calculated from the perimeter and area determined from the top-view SEM image: form factor = (4π area) / (perimeter) 2 Span is defined as [(D90) - (D10)] divided by (D50) and is a measure of the width of the particle size distribution.

[0059] Preferably, the core of the secondary particles corresponds to the particles produced in step (b) and the shell corresponds to the particles produced in step (c) of the method of the present invention.

[0060] In one embodiment of the present invention, the precursor of the present invention has the general formula TM(O) x (OH) y where x and y are average values, and x is in the range of 0 to 1.5, and y is in the range of 0 to 2, and the sum of x+y is at least 1 and at most 2.5.

[0061] In one embodiment of the present invention, TM is of general formula (I) (Ni a Co b Mn c ) 1-d M d (I) It is a combination of metals by During the ceremony, a is in the range of 0.6 to 0.95, preferably 0.8 to 0.92; b is in the range of 0.025 to 0.2, preferably 0.025 to 0.15; c is in the range of 0 to 0.2, preferably 0 to 0.15, and d is in the range of 0 to 0.1, preferably 0 to 0.05; M is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, and Ta; a+b+c=1 is.

[0062] The TM may contain trace amounts of additional metal ions as impurities, such as trace amounts of ubiquitous metals such as sodium, calcium, or zinc, but such trace amounts are not considered within the context of this invention. Trace amounts in this context mean amounts of 0.05 mol % or less, based on the total metal content of the TM.

[0063] The present invention is further illustrated by examples. [Example]

[0064] General Notes Unless otherwise specified, solution percentages refer to weight percent. All pH values ​​were measured outside the stirred tank reactor at 23°C. rpm: Revolutions per minute.

[0065] The terms "average diameter" (D50) and "d50" are used interchangeably. The term "average diameter" refers to the average particle size on a volume basis.

[0066] All experiments were carried out in a continuous stirred tank reactor (volume 3.2 liters) equipped with a two-stage cross-blade stirrer, with a clarifier system attached to the top of the stirred tank reactor. During step (c), aliquots were taken and the particle size distribution was monitored by characterization with dynamic light scattering (DLS).

[0067] I. Precursor Preparation Process (a.1) The following aqueous solutions were prepared: (α.1): Aqueous solution of NiSO4, CoSO4 and MnSO4, molar ratio Ni:Co:Mn=87.0:5.0:8.0, total transition metal concentration: 1.65 mol / kg (β.1): 25% by mass NaOH aqueous solution (γ1): 25% ammonia (NH3) solution.

[0068] Process (b.1): A stirred tank reactor with a capacity of 2.4 L was charged with 2 L of deionized water at 55°C. Overflow occurred at the top of the collection vessel, and the slurry was continuously collected. Solutions (α.1), (β.1) and (γ.1) were continuously fed into the reactor, so that the pH value of the mother liquor was 12.2 and the molar ratio of NH3 to Ni, Co & Mn in the reactor was 0.15. The flow rates of the individual solutions were expressed as f, with i followed by the corresponding solution number. i It is further called the residence time rt = V / (f α +f β +f γ ) = 5h. The particle size distribution in the reactor was monitored by taking samples and characterizing them by dynamic light scattering (DLS). After the reactor had been operated for 15 hours, the particle size distribution did not change any more. Subsequently, the collection vessel was emptied and three seed slurry portions s1, s2 and s3 were collected for 5 hours each. All seed slurry portions had a solids content of 120 g / l and were characterized by the properties listed below. The solids content is defined as g of solids per liter of suspension. The span is defined as (d90-d10) / d50.

[0069] [Table 1]

[0070] I.1 Preparation Procedure for Comparative Precursor C-pCAM.1, Step C-(c.1) A stirred reactor with a capacity of 3.2 L was charged with 1.6 L of deionized water containing 61 g of ammonium sulfate and heated to 55 °C under a nitrogen atmosphere. Subsequently, solution (β.1) was added, the pH was set to 11.8, and the agitator was set to 500 rpm. Subsequently, 320 ml of slurry s1 was added. Solutions (α.1), (β.1), and (γ.1) were continuously fed into the reactor until the pH of the mother liquor was 11.8 and the molar ratio of NH3 to the sum of Ni, Co, and Mn in the reactor was 0.55. The mother liquor was separated from the solids and removed from the reactor by a clarifier attached to the top of the reactor. The flow rates of the individual solutions are indicated by f, with i followed by the corresponding solution number. i It is further called the residence time rt = V / (f α +f β +f γ The stirring speed was kept constant during step C-(c.1). The particles grew until they reached a particle size of approximately 13-14 μm. The particles were then filtered, washed with deionized water, dried, and sieved using a 30 μm mesh size to obtain C-pCAM.1.

[0071] I.2 Preparation Procedure for Comparative Precursor C-pCAM.2, Step C-(c.2) A stirred reactor with a capacity of 3.2 L was charged with 1.6 L of deionized water containing 61 g of ammonium sulfate and heated to 55 °C under a nitrogen atmosphere. Subsequently, solution (β.1) was added, the pH was set to 12.05, and the agitator was set to 1000 rpm. Subsequently, 320 ml of slurry s2 was added. Solutions (α.1), (β.1), and (γ.1) were continuously fed into the reactor until the pH of the mother liquor was 12.05 and the molar ratio of NH3 to the sum of Ni, Co, and Mn in the reactor was 0.55. The mother liquor was continuously separated from the solids and removed from the reactor by a clarifier attached to the top of the reactor. The flow rates of the individual solutions are indicated by f, with i followed by the corresponding solution number. i It is further called the residence time rt = V / (f α +f β +f γThe stirring speed was kept constant during step C-(c.2). The particles grew until they reached a particle size of approximately 13-14 μm. The particles were then collected by filtration, washed with deionized water, dried under air, and sieved using a 30 μm mesh size to obtain C-pCAM.2.

[0072] I.3 Procedure for preparing precursor pCAM.3 of the present invention, step (c.3) A stirred reactor with a capacity of 3.2 L was charged with 1.6 L of deionized water containing 61 g of ammonium sulfate and heated to 55 °C under a nitrogen atmosphere. Subsequently, solution (β.1) was added, the pH was set to 12.05, and the agitator was set to 1000 rpm. Subsequently, 320 ml of slurry s3 was added. Solutions (α.1), (β.1), and (γ.1) were continuously fed into the reactor until the pH of the mother liquor was 12.05 and the molar ratio of NH3 to the sum of Ni, Co, and Mn in the reactor was 0.55. The mother liquor was continuously separated from the solids and removed from the reactor by a clarifier attached to the top of the reactor. The flow rates of the individual solutions are represented by f, with i followed by the corresponding solution number. i It is further called the residence time rt = V / (f α +f β +f γ The stirring speed was adjusted to satisfy ) = 5h. The stirring speed was first kept at 1000 rpm, then reduced to 650 rpm when the particles reached 12 μm, and finally reduced to 500 rpm when the particles reached 12 μm. The particles grew until they reached a particle size of approximately 13-14 μm. The particles were then subsequently filtered, washed with deionized water, dried, and sieved using a 30 μm mesh size to obtain pCAM.3 of the present invention.

[0073] [Table 2]

[0074] [Table 3]

[0075] Ni 2+ The solubility in the liquid phase was determined by ICP-OES after filtration.

Claims

1. 1. A method for producing particulate (oxy)hydroxide of TM having an average particle size D50 in the range of 5 to 16 μm as determined by light scattering or LASER diffraction or electroacoustic spectroscopy, wherein the TM comprises nickel, the method comprising the steps of: (a) an aqueous solution (α) containing Ni and Co, and optionally at least one further metal selected from Mn, Ti, Zr, Mo, W, Al, Mg, Nb, and Ta; and an aqueous solution (β) containing an alkali metal hydroxide; and optionally an aqueous solution containing ammonia (γ) providing (b) combining solution (α) with solution (β) and, if applicable, solution (γ) in a stirred tank reactor at a pH value in the range of 12.0 to 13.0, thereby producing solid particles of nickel-containing hydroxide, and slurrying the solid particles; (c) transferring at least a portion of the slurry obtained in step (b) to another stirred tank reactor and combining it with solution (α), solution (β), and, if applicable, solution (γ), at a pH value in the range of 11.0 to 12.7 under conditions in which the solubility of nickel is higher than in step (b); Including, The TM is represented by the general formula (I): (Nia Co b Mn c ) 1-d M d (I) It is a combination of metals by During the ceremony, a is in the range of 0.6 to 0.95; b is in the range of 0.025 to 0.2; c is in the range of 0 to 0.2, and d is in the range of 0 to 0.1; M is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, and Ta; a+b+c=1, The method wherein the stirring speed is reduced during step (c).

2. The method of claim 1 , wherein the particulate mixed transition metal precursor is an (oxy)hydroxide.

3. 3. The process according to claim 1 or 2, wherein step (b) has a duration ranging from rt·0.03 to rt·0.10, and rt is the average residence time in the reactor in which steps (b) and (c) are carried out.

4. 4. The method of claim 1, wherein the stirring speed at the start of step (c) is slower than at the end of step (b).

5. 5. The method according to claim 1, wherein the stirring speed in step (c) is continuously reduced.

6. 5. The method according to claim 1, wherein the stirring speed in step (c) is reduced stepwise.

7. 7. The method of claim 1, wherein the ammonia concentration in step (c) is higher than in step (b).

8. 8. The method according to claim 1, wherein the pH value in step (c) is at least 0.2 lower than in step (b).

9. 9. The method according to claim 1, wherein the solution (α) used in step (c) has a different composition compared to the solution (α) used in step (b).

10. 6. The method according to claim 5, wherein the nickel content of the solution (α) used in step (c) is lower than the nickel content of the solution (α) used in step (b).

11. 11. The method according to claim 1, wherein the rate of addition of solutions (α) and (β), and, if applicable, solution (γ), is reduced in the course of step (c).

12. 12. The method of any one of claims 1 to 11, wherein the stirring speed is reduced by a factor of 0.25 to 0.75 during step (c).

13. 1. A particulate mixed metal (oxy)hydroxide comprising Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, and composed of secondary particles which are agglomerates of primary particles, wherein the average particle size D50 of the secondary particles is in the range of 5 to 16 μm as determined by light scattering, LASER diffraction, or electroacoustic spectroscopy, the primary particles have a predominantly radial orientation in the shell and the primary particles are predominantly randomly oriented in the core, and the secondary particles have a product of span and form factor in the range of 0.3 to 0.6, the span being defined as (D90-D10) / D50 and the form factor being defined as (4π·area) / (perimeter)2, and further wherein the secondary particles have a ratio of secondary particle size to core diameter of less than 7.

5.

14. 1. A particulate mixed metal (oxy)hydroxide comprising Ni, at least one transition metal selected from Co and Mn, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, and composed of secondary particles which are agglomerates of primary particles, wherein the average particle size D50 of the secondary particles is in the range of 5 to 16 μm as determined by light scattering, LASER diffraction, or electroacoustic spectroscopy, the primary particles have a predominantly radial orientation in the shell and the primary particles are predominantly randomly oriented in the core, and the secondary particles have a product of span and form factor in the range of 0.8 to 1.4, the span being defined as (D90-D10) / D50 and the form factor being defined as (4π·area) / (perimeter) 2 , and further wherein the secondary particles have a ratio of secondary particle size to core diameter in the range of 1.2 to 1.6.

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