Method for producing a precursor of a cathode active material for a lithium-ion battery

Abstract

A method for producing a particulate (oxy)hydroxide of TM, wherein TM represents a combination of metals, TM comprising nickel and at least one metal selected from cobalt, aluminum and manganese, said method comprising the steps of: (a) combining an aqueous slurry of metallic nickel and at least one metal selected from aluminum and transition metals other than nickel with an oxidizing agent selected from oxygen and nitrates in a first reaction vessel or in a first group of reaction vessels at a temperature between 5° C. and 40° C.; (b) transferring the aqueous reaction medium from the first reaction vessel to a second reaction vessel, said second reaction vessel containing a slurry of TM hydroxide, the pH value in step (b) being higher than in step (a) and the temperature being in the range of 45° C. to 80° C., thereby forming and growing particles of TM hydroxide; (c) removing the particles from step (b) from the liquid by solid-liquid separation and drying the particles; (d) returning the liquid phase obtained in step (c) to the first reactor. Includes.

Description

[Technical field]

[0001] The present invention relates to a method for producing a particulate (oxy)hydroxide of TM, wherein TM represents a combination of metals, TM comprising nickel and at least one metal selected from cobalt, aluminum and manganese, said method comprising the following steps: (a) combining an aqueous slurry of metallic nickel and at least one metal selected from aluminum and transition metals other than nickel with an oxidizing agent selected from oxygen, peroxides and nitrates in a first reaction vessel or in a first group of reaction vessels at a temperature between 5° C. and 40° C.; (b) transferring the aqueous reaction medium from step (a) to a second reaction vessel, said second reaction vessel containing a slurry of TM hydroxide, the pH value of step (b) being higher than that of step (a) and the temperature being in the range of 45° C. to 80° C., thereby forming and growing particles of TM hydroxide; (c) removing the particles from step (b) from the liquid by solid-liquid separation and drying the particles; (d) returning the liquid phase obtained in step (c) to the first reactor. Includes. [Background technology]

[0002] Lithium-ion secondary batteries are modern devices for storing energy. Many applications have been considered, from small devices such as mobile phones and laptop computers to car batteries and other e-mobility batteries. Various battery components, such as electrolytes, electrode materials, and separators, have important roles in the performance of the battery. Cathode materials have received particular attention. Several materials have been proposed, such as lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide.

[0003] The cathode material is of great importance for the performance of lithium-ion batteries. Lithium-containing mixed transition metal oxides, such as spinel and layered structure mixed oxides, in particular lithium-containing mixed oxides of nickel, manganese and cobalt, have become of particular importance (see, for example, EP 1 189 296). Such lithium-containing mixed oxides of nickel, manganese and cobalt are generally prepared in a two-stage process. In a first stage, they are prepared by precipitating a sparingly soluble salt, such as a carbonate or hydroxide, of the transition metal(s) from a solution. This sparingly soluble compound is often also called the precursor. In a second stage, the precursor is reacted with a lithium compound, such as Li 2 CO 3 , LiOH or Li 2 O and sintered at high temperatures, for example, 600 to 1100°C.

[0004] In the precursor manufacturing process, when carried out by (co)precipitation, sulfates of transition metals such as nickel, cobalt and manganese are usually used as starting materials. However, this leads to the production of stoichiometric amounts of alkali metal sulfates, which are undesirable by-products and must be disposed of.

[0005] WO 2019 / 191837 discloses a method in which the cathode active material is made from a precursor made by simultaneous precipitation with oxidation of the metal. However, this method has the drawback that manganese is not well incorporated into the precursor under typical alkaline conditions, resulting in MnO. 2 This is disadvantageous when manganese is present because it can precipitate as a phosphate ions. Furthermore, magnetic separation proposed to remove unreacted metals does not work for many materials, including but not limited to aluminum and manganese. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] EP 1 189 296 [Patent Document 2] WO 2019 / 191837 Summary of the Invention [Problem to be solved by the invention]

[0007] It was therefore an object of the present invention to provide a method for the preparation of a precursor which avoids the formation of stoichiometric amounts of alkali metal sulfates and further reduces the formation of residues of unreacted metals which cannot be magnetically removed. In particular, it was an object of the present invention to provide a method which allows the use of manganese as a constituent. [Means for solving the problem]

[0008] Method of the invention or method according to the invention (present) The method of the invention may be carried out as a batch process or as a continuous or semi-continuous process. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 shows a schematic diagram of an apparatus for carrying out the method of the present invention. [Diagram 2] FIG. 2 shows an SEM image of p-CAM.1. [Diagram 3] FIG. 3 shows an SEM image of p-CAM.1. [Figure 4] FIG. 4 shows an SEM image of p-CAM.1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method of the present invention comprises steps (a)-(d), hereinafter also referred to as (a), (b), (c) or (d), respectively, which are described in more detail below.

[0011] The process of the invention is suitable for the production of particulate (oxy)hydroxides of TM, where TM stands for a metal and TM comprises nickel and at least one metal selected from cobalt, aluminium and manganese. Preferably, TM comprises at least 50 mol% nickel. More preferably, TM comprises at least 50 mol% nickel and at least one of manganese and aluminium.

[0012] In one embodiment of the invention, the particulate (oxy)hydroxide of TM is selected from hydroxides and oxyhydroxides of TM, where TM is a combination of metals according to general formula (I): (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.6 to 0.95, preferably 0.80 to 0.94, b is in the range of 0 to 0.2, preferably 0.01 to 0.12; c is in the range of 0 to 0.2, preferably 0.02 to 0.10; d is in the range of 0 to 0.1; M is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, Ta, and combinations of at least two of the foregoing, preferably M is selected from Mg and Al; a+b+c=1 and c+d>0).

[0013] The particulate (oxy)hydroxides of the TM may contain, as impurities, trace amounts of further metal ions, e.g. trace amounts of ubiquitous metals such as sodium, calcium, iron or zinc, but such trace amounts are not taken into account in the context of the present invention, trace amounts in this context meaning amounts of 0.05 mol % or less relative to the total metal content of the TM.

[0014] The particulate (oxy)hydroxide of TM is in a particulate state. In one embodiment of the invention, the mean particle size (D50) of the particulate (oxy)hydroxide of TM is in the range of 2 to 20 μm, preferably 3 to 16 μm, more preferably 7 to 14 μm. Mean particle size (D50) in the context of the present invention refers to the median volume-based particle diameter, determined for example by light scattering. In one embodiment, the particulate (oxy)hydroxide of TM has a unimodal particle size distribution. In another embodiment, the particle size distribution of the particulate (oxy)hydroxide of TM may be bimodal, for example with one maximum in the range of 1 to 5 μm and a further maximum in the range of 7 to 16 μm. A unimodal distribution is preferred.

[0015] In another embodiment of the present invention, the average particle size (D50) of the particulate (oxy)hydroxide of the TM is in the range of 1 to 7 μm, preferably 2 to 6 μm, and more preferably 3 to 5 μm.

[0016] The particle shape of the secondary particles of the particulate (oxy)hydroxide of TM is preferably spherical, i.e., particles having a spherical shape. Spherical includes not only particles that are exactly spherical, but also particles having a form factor in the range of 0.7 to 1 and a bounding box axial ratio in the range of 1.00 to 1.25. To determine the bounding box axial ratio of a particular particle, a rectangular bounding box as small as possible is set around a top-view SEM image of the particle. The axial ratio is calculated by dividing the length of two sides a 1 and a 2 (a 1 ≧a 2 ) so the axis ratio of the bounding box = a 1 / a 2 It is calculated by:

[0017] A perfect sphere would have a bounding box axis ratio of 1.0, but any deviation from a perfect sphere would have an axis ratio > 1.0.

[0018] To determine the shape factor and axial ratio of a sample, both properties are first determined for at least 50 individual particles of each sample and then averaged. The shape factor of an individual particle is calculated from the perimeter and area determined from the top-view SEM image: Shape factor = (4π area) / (perimeter) 2 A perfect sphere has a shape factor of 1.0, but any deviation from a perfect sphere will result in a shape factor less than 1.0.

[0019] In one embodiment of the invention, the TM particulate (oxy)hydroxide is composed of secondary particles which are composites of primary particles. Preferably, the precursor is composed of spherical secondary particles which are agglomerates of primary particles. Even more preferably, the precursor is composed of spherical secondary particles which are agglomerates of plate-, rod- or needle-shaped primary particles or platelets.

[0020] In one embodiment of the invention, the particulate (oxy)hydroxide of the TM comprises a specific amount, e.g. 0.1-10 mol % relative to the TM, of a metal in the zero oxidation state, e.g. nickel, which is a constituent of the TM. The metal in the zero oxidation state, in particular nickel, is incorporated in the form of small particles of the maximum size of the particulate (oxy)hydroxide itself.

[0021] In one embodiment of the invention, the particulate (oxy)hydroxide of the TM may have a particle size distribution span in the range of 0.5 to 0.9, the span being defined as [(D90)-(D10)] divided by (D50), all determined by LASER analysis. In another embodiment of the invention, the precursor may have a particle size distribution span in the range of 1.1 to 1.8.

[0022] In one embodiment of the present invention, the specific surface area (BET) of the precursor is 2 to 10 m 2 / g or 15~100m 2 / g and is determined, for example, by nitrogen adsorption according to DIN-ISO 9277:2003-05.

[0023] In one embodiment of the present invention, in the XRD spectrum of the particulate (oxy)hydroxide of TM, the intensity of the reflection at an angle 2θ=20.11±0.5° divided by the intensity of the peaks at angles 2θ=8.86±0.5° and 2θ=15.08±0.5° from MoKα1 X-ray diffraction is in the range of 0.01 to 0.25.

[0024] The method of the present invention is carried out in an apparatus comprising at least two reaction vessels, hereinafter referred to as the first reaction vessel and the second reaction vessel. Both reaction vessels are connected to each other, for example via a pipe system, preferably via at least two independent pipes. Furthermore, the apparatus contains at least one device for solid-liquid separation, for example by filtration or centrifugation, preferably by filtration.

[0025] In one embodiment of the invention, the process of the invention is carried out in an apparatus comprising at least two tank reactors connected to each other by two pipes configured for transferring a slurry or an aqueous solution from a first reactor vessel to a second reactor vessel, another pipe connected to a device for solid-liquid separation and another pipe for transferring all or part of the liquid phase resulting from the solid-liquid separation to the first reactor vessel.

[0026] In one embodiment of the invention, the second reaction vessel is equipped with a device for removing a liquid phase, such as a clarifier, a candle filter or a membrane, after which all or part of said liquid phase can be returned to step (a).

[0027] In one version of the invention, the first reaction vessel is embodied as a group of vessels, for example a two or three tank reactor. In each reaction vessel of such group, the reaction according to step (a) may be carried out with the same combination of TMs or only with certain members. The aqueous reaction media obtained in the different reaction vessels are combined for subjecting to step (b).

[0028] In one embodiment of the present invention, the first reaction vessel may have a device for discharging the slurry or aqueous solution, for example, the slurry or aqueous solution may be discharged to the second reaction vessel by an overflow or a valve.

[0029] In step (a), an aqueous slurry of metallic nickel and at least one metal selected from aluminum and a transition metal other than nickel is combined in a first reaction vessel with an oxidizing agent selected from oxygen and a nitrate, preferably such transition metal other than nickel being selected from cobalt, manganese, and a combination of cobalt and manganese.

[0030] The metallic nickel may be in the form of powder, sheets, shavings, briquettes, pellets, rounds, nodules, electrode pieces. The powders may have an average particle size ranging from 0.01 to 1 mm. The sheets may have a thickness ranging from 0.1 mm to 5 mm, and lengths and widths ranging from 2 cm to 10 m, in particular from 2 cm to 10 cm, which may be the same or different. Shavings for the purposes of the present invention may have a thickness of 0.1 to 1 mm, a width of 1 mm to 5 mm and a length of 1 cm to 20 cm. The nodules may have a diameter ranging from 1 mm to 5 cm, but have an irregular shape. The electrode pieces may have a thickness of 0.5 to 7 mm, and an average diameter of 10 to 40 mm.

[0031] The rounds have a diameter of 2-3 cm and a height of about 0.8-1.5 cm; the briquettes have a length of 2-5 cm, a width of 1-4 cm, and a height of 1-3 cm, the length being greater than the height. For the purposes of the present invention, the pellets have a diameter of 1-2 cm.

[0032] The aluminum and transition metals other than nickel may be in the form of powders, sheets, shavings, or nodules, the dimensions of which are as defined above for nickel.

[0033] The molar ratio of nickel to aluminum or optionally the transition metal preferably corresponds to the stoichiometry of the desired product. In another embodiment, the metal more noble than nickel is employed in molar excess.

[0034] In one embodiment of step (a), the mass ratio of water to nickel and TM metals other than nickel is in the range of 20:1 to 0.1:1, preferably 10:1 to 0.5:1.

[0035] In step (a) an oxidizing agent is present. The oxidizing agent is selected from oxygen and a nitrate. The nitrate can be introduced as an alkali metal nitrate or as nitric acid. Preferably, the oxygen is present in the form of air.

[0036] In one embodiment of the invention, step (a) is carried out in the absence of oxygen and the oxidation is carried out by using an alkali metal nitrate, such as sodium nitrate or potassium nitrate, or by using nitric acid, or a combination of nitric acid and an alkali metal nitrate. By absence of oxygen is meant a gas atmosphere having 10 ppm oxygen by volume.

[0037] In one embodiment of the invention, in step (a) a gas selected from oxygen, air or nitrogen is purged through the reaction medium and in step (b) nitrogen is purged through the reaction medium. In another embodiment of the invention, the flow rates of the gases are different in steps (a) and (b).

[0038] Step (a) is preferably carried out by a mixing operation, for example by stirring, although on a laboratory scale shaking is also possible.

[0039] Step (a) is carried out at a temperature in the range of 5 to 40°C, preferably in the range of 15 to 35°C.

[0040] In one embodiment of the invention, step (a) is carried out at a pressure in the range of 0.5 bar (abs.) to 10 bar (abs.), preferably for reasons of simplicity at atmospheric pressure or at a pressure slightly above atmospheric pressure, for example 1 to 20 mbar above atmospheric pressure.

[0041] The residence time of the aqueous medium in step (a) (in the case of continuous mode, the average hydraulic residence time) is in the range of 30 minutes to 5 hours.

[0042] In one embodiment of the invention, step (a) is carried out in the presence of a complexing agent selected from ammonia, borate, polyborate, glycine, tartrate, citrate, and oxalate. In certain embodiments of the invention, step (a) is carried out in the presence of ammonia and a complexing agent selected from borate, polyborate, glycine, tartrate, citrate, and oxalate. In such embodiments, such complexing agent other than ammonia is present in the range of 0.1 to 10 moles per mole of nickel.

[0043] It is preferred to carry out the process of the invention in the presence of ammonia, which can be used as a complexing agent and for pH adjustment. Furthermore, when nitrates are used as oxidizing agents, ammonia is generated during step (a).

[0044] In one embodiment of the invention, step (a) is carried out in a single reaction vessel, e.g. a stirred tank reactor. In another embodiment of the invention, step (a) is carried out in a group of reaction vessels, e.g. 2 to 10 reaction vessels, also referred to as the first reaction vessel or first group. The reaction vessels of said first group may comprise two or more tank reactors, e.g. up to 10 tank reactors. In each of the reaction vessels of the first group, the same or different metals of the TM may be treated according to the conditions according to step (a). For example, in one reaction vessel, nickel is combined with an oxidant in the presence of ammonia at a temperature between 5°C and 40°C, and in another reaction vessel, cobalt or manganese or aluminum is combined with an oxidant in the presence of ammonia at a temperature between 5°C and 40°C.

[0045] By carrying out step (a), an aqueous reaction medium is obtained. The aqueous reaction medium may be in the form of a solution or a slurry. In particular, the aqueous reaction medium does not contain seed particles that may lead to the precipitation of hydroxides of TM. In particular, the aqueous reaction medium does not contain precipitated manganese dioxide particles. Preferably, the reaction medium has a pH value in the range of 7.5 to 10.0.

[0046] In step (b), the aqueous reaction medium is transferred from the first reaction vessel to a second reaction vessel. The second reaction vessel contains a slurry of TM hydroxide. The temperature at which step (b) is carried out is in the range of 45-80°C, preferably 55-70°C. The pH value in step (b), and thus in the second reaction vessel, is for example 0.5-6 units, preferably 1-3 units, higher than the pH value in step (a) and thus in the first reaction vessel. In step (b), TM hydroxide particles are formed and grown.

[0047] In one embodiment of the present invention, the pH value in step (a) is in the range of 7.0 to 10.0, and the pH value in step (b) is in the range of 9.0 to 13.0.

[0048] If the pH value in step (a) is 10, the pH value in step (b) is higher, for example at least 10.5, preferably at least 11. In an embodiment in which the pH value in step (b) is 9.0, the pH value in step (a) is lower, for example up to 8.5, preferably up to 8.0. More preferably, the pH value in step (b) is in the range of 10.5 to 13.

[0049] It is preferred to minimize the amount of oxygen in step (b), but step (b) may contain up to 500 ppm O 2 , preferably up to 50 ppm O 2 , and even more preferably up to 10 ppm O 2 In the context of step (b), ppm means parts per million by volume.

[0050] In the second reaction vessel, hydroxides of TM are precipitated. In part, such hydroxides form on pre-existing particles of TM hydroxide, with such pre-existing particles acting as seeds. In part, however, new particles are formed during step (b).

[0051] In one embodiment of the invention, seed particles are added to the reaction vessel in step (b). In another embodiment of the invention, the seed particles are generated by depletion of existing secondary particles in the reactor in step (b) by an integrated high shear device such as a rotor-stator device.

[0052] In one embodiment of the invention, step (b) is carried out at a pH value in the range from 9 to 13, preferably in the range from 9.5 to 12.5. The limit value is selected such that the pH value in step (b) is higher than in step (a).

[0053] In one embodiment of the invention, the metal particles are removed from the aqueous reaction medium of step (a) by filtration or sedimentation or magnetic separation and returned to the first reaction vessel. The magnetic separation step is effective for ferromagnetic metals such as cobalt and nickel. The metal particles may have the size of the metal as introduced in step (a) or may be smaller due to partial but incomplete reaction.

[0054] In one embodiment of the invention, step (b) is carried out at a pressure in the range of 0.5 bar (abs.) to 10 bar (abs.), preferably for reasons of simplicity at atmospheric pressure or at a pressure slightly above atmospheric pressure, for example 1 to 20 mbar above atmospheric pressure.

[0055] The residence time of the aqueous medium in step (b) (in the case of continuous mode, the average hydraulic residence time) is in the range of 30 minutes to 15 hours.

[0056] During step (b), a mixing operation, for example stirring, is preferably carried out.

[0057] In one embodiment of the invention, the temperature during step (a) is, for example, at least 5° C., preferably at least 10° C. lower than during step (b). The maximum temperature difference between steps (a) and (b) may range from 40° C. In another embodiment, the temperatures in steps (a) and (b) are the same.

[0058] During step (b), new particulate hydroxides of TM slurried in the liquid mother liquor are formed and particles of existing TM hydroxide are generated. Without wishing to be bound by any theory, it is believed that higher pH values ​​in step (b) result in a higher rate of newly formed particles and a lower rate of particle generation. Furthermore, it is also observed that lower pH values ​​in step (b) result in a higher rate of particle generation and a lower rate of new particle formation.

[0059] In one embodiment of the invention, no addition of an alkali metal hydroxide is required in either step (a) or step (b).

[0060] In one embodiment of the present invention, at least one manganese or aluminum compound is added in step (b). Examples of manganese compounds include MnSO. 4 or MnCl 2 or preferably manganese(II) acetate, or even more preferably Mn(NO 3 ) 2 The water of hydration is ignored. Examples of aluminum compounds include Al 2 (SO 4 ) 3 , KAl(SO 4 ) 2 , Al(NO 3 ) 3 , and NaAl(OH) 4 Examples include:

[0061] Step (c) comprises removing the particles from step (b) from the liquid by a solid-liquid separation method and drying the particles thus obtained. In particular, step (c) comprises removing the slurry formed in step (b) and subjecting said slurry to a solid-liquid separation, such as decantation or centrifugation or filtration, with filtration being preferred. Preferred embodiments of solid-liquid separation are filter presses and belt filters.

[0062] In a preferred embodiment of step (c), a filter cake is formed as the solid phase, and a filtrate is obtained as the liquid phase.

[0063] In one embodiment of the present invention, the filter cake may be subjected to a purification step, such as rinsing with water or aqueous ammonia, aqueous alkali metal or aqueous alkali carbonate solution. A magnetic separation step may also be performed before or after drying to remove unreacted nickel or cobalt, or other ferromagnetic impurities such as iron.

[0064] In a preferred embodiment, the precursor is dried, for example, under air at a temperature in the range of 80-140° C. In another preferred embodiment, the precursor is dried, for example, under air at a temperature in the range of 80-140° C. and then under air at a temperature in the range of 150-600° C.

[0065] During the course of step (c), the hydroxide of TM may be dried in one or more substeps, for example at least two substeps at different temperatures, for example substep 1 at 80-150°C and substep 2 at 165-600°C. Preferably, the residual moisture content of the TM (oxy)hydroxide is less than or equal to 5% by weight, for example 0.01-0.2% by weight. In the context of the present invention, the moisture content is expressed as g H per 100 g of TM (oxy)hydroxide. 2 O. In this case, H 2 O may be chemically bonded as a hydroxyl group or may be bonded by physical adsorption. The residual water content in the hydroxide of TM is preferably low, for example, 0.1 to 5 mass %.

[0066] In one embodiment of the present invention, sub-step 1 is preferably carried out in a spray dryer, a fluidized bed dryer, a spin flash dryer, or a contact dryer, such as a paddle dryer or a pan dryer. Sub-step 2 can be carried out in a rotary kiln, a roller heat kiln, or a box kiln.

[0067] The drying is carried out in the presence of air, which may result in partial oxidation, in particular manganese, if present, being partially oxidized to the (+III) or (+IV) oxidation stage.

[0068] Step (d) comprises returning all or a part of the liquid phase obtained in step (c) to the first reaction vessel. In one embodiment of the present invention, 80-99% by volume of the liquid is returned to the first reaction vessel.

[0069] By carrying out the method of the present invention, a precursor with excellent morphology can be obtained, and Na 2 SO 4 The formation of by-products such as solutions of lithium is extremely low. 2 CO 3 and heat-treating the resultant cathode active material at 600 to 1,000° C. in a rotary kiln or roller hearth kiln, for example, a cathode active material having good properties and morphology can be obtained.

[0070] Another aspect of the invention relates to a particulate (oxy)hydroxide, hereinafter also referred to as the precursor of the invention, which is a particulate (oxy)hydroxide of TM, wherein TM comprises nickel and at least one metal selected from cobalt, manganese and aluminium, and which further comprises at least one metal of TM in the zero oxidation state, for example in an amount of 0.1-10 mol % relative to TM.

[0071] In one embodiment of the present invention, in the XRD spectrum of the precursor of the present invention, the value obtained by dividing the intensity of the reflection at an angle 2θ=20.11±0.5° by the intensity of the peaks at angles 2θ=8.86±0.5° and 2θ=15.08±0.5° from MoKα1 X-ray diffraction is in the range of 0.01 to 0.25.

[0072] In one embodiment of the present invention, the precursors of the present invention are selected from hydroxides and oxyhydroxides of TM, where TM is a combination of metals according to general formula (I): (Ni a Co b Mn c ) 1-d M d (I) (In the formula, a is in the range of 0.6 to 0.95, preferably 0.80 to 0.94, b is in the range of 0 to 0.2, preferably 0.01 to 0.12; c is in the range of 0 to 0.2, preferably 0.02 to 0.10; d is in the range of 0 to 0.1; M is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, Ta, and combinations of at least two of the foregoing, preferably M is selected from Mg and Al; a+b+c=1 and c+d>0).

[0073] The precursors of the invention may contain, as impurities, trace amounts of further metal ions, e.g. trace amounts of ubiquitous metals such as sodium, calcium, iron or zinc, but such trace amounts are not taken into account in the context of the present invention, trace amounts in this context meaning amounts of 0.05 mol % or less relative to the total metal content of the TM.

[0074] The particulate (oxy)hydroxide of TM is in a particulate state. In one embodiment of the present invention, the mean particle size (D50) of the precursor of the present invention is in the range of 2 to 20 μm, preferably 3 to 16 μm, more preferably 7 to 14 μm. The mean particle size (D50) in the context of the present invention refers to the median volume-based particle diameter, determined for example by light scattering. In one embodiment, the precursor of the present invention has a unimodal particle size distribution. In another embodiment, the particle size distribution of the precursor of the present invention may be bimodal, for example with one maximum in the range of 1 to 5 μm and a further maximum in the range of 7 to 16 μm. A unimodal distribution is preferred.

[0075] In another embodiment of the present invention, the average particle size (D50) of the precursor of the present invention is in the range of 1 to 7 μm, preferably 2 to 6 μm, and more preferably 3 to 5 μm.

[0076] The particle shape of the secondary particles of the precursor of the present invention is preferably spherical, i.e., particles having a spherical shape. Spherical includes not only particles that are exactly spherical, but also particles having a shape factor in the range of 0.7 to 1 and an axial ratio of the bounding box in the range of 1.00 to 1.25. To determine the axial ratio of the bounding box of a particular particle, a rectangular bounding box as small as possible is set around a top-view SEM image of the particle. The axial ratio is calculated by dividing the length of the two sides a 1 and a 2 (a 1 ≧a 2 ) so the axis ratio of the bounding box = a 1 / a 2 It is calculated by:

[0077] A perfect sphere would have a bounding box axis ratio of 1.0, but any deviation from a perfect sphere would have an axis ratio > 1.0.

[0078] To determine the shape factor and axial ratio of a sample, both properties are first determined for at least 50 individual particles of each sample and then averaged. The shape factor of an individual particle is calculated from the perimeter and area determined from the top-view SEM image: Shape factor = (4π area) / (perimeter) 2 A perfect sphere has a shape factor of 1.0, but any deviation from a perfect sphere will result in a shape factor less than 1.0.

[0079] In one embodiment of the present invention, the precursor of the present invention is composed of secondary particles which are composites of primary particles.Preferably, the precursor is composed of spherical secondary particles which are aggregates of primary particles.Even more preferably, the precursor of the present invention is composed of spherical secondary particles which are aggregates of plate-, rod- or needle-shaped primary particles or platelets.

[0080] The precursor of the present invention comprises a specific amount, e.g. 0.1-10 mol % with respect to the TM, of a metal in the zero oxidation state, e.g. nickel, which is a constituent of the TM. The metal in the zero oxidation state, in particular nickel, is incorporated in the form of small particles with the maximum size of the particulate (oxy)hydroxide itself.

[0081] In one embodiment of the invention, the precursor of the invention may have a particle size distribution span in the range of 0.5 to 0.9, the span being defined as [(D90)-(D10)] divided by (D50), all determined by LASER analysis. In another embodiment of the invention, the precursor may have a particle size distribution span in the range of 1.1 to 1.8.

[0082] In one embodiment of the present invention, the specific surface area (BET) of the precursor of the present invention is 2 to 10 m 2 / g or 15~100m 2 / g and is determined, for example, by nitrogen adsorption according to DIN-ISO 9277:2003-05.

[0083] Preferably, the precursors of the invention exhibit, for example in SEM analysis, plate-like crystallites arranged with their long axes at an angle of 90(±10)° to the diameter of the secondary particles.

[0084] Advantageously, the precursors of the present invention are obtained by the method of the present invention. They are very suitable for the manufacture of cathode active materials. Without wishing to be bound by any theory, it is hypothesized that the trace amounts of metallic nickel present in the precursors of the present invention are easily oxidized during the reaction with a lithium source in an oxidizing atmosphere.

[0085] Advantageously, the method of the invention comprises the steps of: (A) a first reaction vessel including an agitator and a pipe connected to the agitator; (B) a second reaction vessel including an agitator and a pipe connected to the agitator; (C) A device for solid-liquid separation selected from a filter and a centrifuge, and an additional pipe for returning the filtrate to the reaction vessel (A). The method is carried out in an apparatus including:

[0086] In one embodiment of the present invention, the apparatus includes a group of 2 to 10 first reaction vessels (A), each of which includes an agitator and a pipe connected to a reaction vessel (B).

[0087] A preferred device (C) is a filter, for example a belt filter.

[0088] In one embodiment of the invention, the apparatus in which the inventive process is preferably carried out comprises at least two tank reactors (A) and (B) connected to each other by two pipes arranged for the transfer of a slurry or aqueous solution from the tank reactor (A) to the tank reactor (B), another pipe connected to a device for solid-liquid separation (C) and another pipe for the transfer of all or part of the liquid phase to the tank reactor (A).

[0089] In one embodiment of the invention, the apparatus further contains a buffer device in which the slurry from step (b) is stored before carrying out step (c) or in which the mother liquor is stored before being returned to the reaction vessel (A).

[0090] In one embodiment of the invention, the second reaction vessel (B) is equipped with a device for removing a liquid phase, such as a clarifier, a candle filter or a membrane, after which all or part of said liquid phase can be returned to reaction vessel (A).

[0091] In one version of the invention, the first reaction vessel (A) is embodied as a group of vessels, for example a two or three tank reactor. In each reaction vessel of such group, the reaction according to step (a) may be carried out with the same combination of TMs or only with certain members. The aqueous reaction media obtained in the different reaction vessels (A) are combined to feed the second reaction vessel (B).

[0092] The invention is further illustrated by examples and figures. EXAMPLES

[0093] The following reactions were carried out in an apparatus according to schematic diagram 1. The reaction vessels (A.1) and (B.1) are 3.2 1 stirred tank reactors. rpm: revolutions per minute.

[0094] Step (a.1): An aqueous solution containing 1 M ammonium nitrate and 0.5 M sodium nitrate was placed in a reaction vessel (A.1). The solution was heated to 35°C, the pH value was adjusted to 10.0 by adding ammonia, and air was bubbled through the solution. Nickel and cobalt metal powders (average particle size 0.1-1 mm) were added and the reaction mixture was stirred at 700 rpm. The solid content in the reaction vessel (A.1) was 20% by mass. The molar ratio of nickel to cobalt in the solid was about 20:1. The suspension was filtered in a device (E.1). The unreacted metal particles were recycled to the reaction vessel (A.1).

[0095] Step (b.1): The liquid phase was fed to the reaction vessel (B.1) and heated to 60 ° C. Furthermore, nickel / cobalt / manganese hydroxide seeds and an aqueous manganese nitrate solution were fed to the reaction vessel (B.1) in such a way that the molar ratio of Ni:Co:Mn in the liquid was 91:4.5:4.5. The solid content in B was about 20% by mass. The slurry in the reaction vessel (B.1) was aerated with nitrogen. The pH value was adjusted to 12 by adding ammonia. The particle-free liquid phase was continuously removed from the reaction vessel B.1 by a solid-liquid separator and about 90% was returned to the reaction vessel (A.1). In parallel with the removal of the liquid phase, the formed suspension was continuously discharged from the reaction vessel (B.1). Residual metal particles were partially removed by magnetic separation. The suspension was then filtered through a filter C.1. The liquid phase was recycled to the reaction vessel (A.1). The filter cake was washed with deionized water and dried in D.1 at 120°C for 16 hours to obtain P-CAM.1 with a molar composition of Ni:Co:Mn=91:4.5:4.5, an average particle size (d50) of 11.8 μm, and a span of 1.24. P-CAM.1 contains some unreacted nickel.

[0096] Powder X-ray diffraction (PXRD) data were advantageously collected using a laboratory diffractometer (D8 Discover, Bruker AXS GmbH, Karlsruhe). The diffractometer was set up with a molybdenum X-ray tube. A bent germanium Johansson primary spectrometer was used to monochromatize the characteristic K-α1 radiation. Data were collected in Bragg-Brentano reflection geometry. A LYNXEYE area detector was utilized to collect the scattered X-ray signal.

[0097] p-CAM.1 was ground using an IKA tube mill and a MT40.100 disposable grinding chamber. The powder was placed in a sample holder and flattened with a glass plate.

[0098] P-CAM.1 was mixed with LiOH monohydrate in a molar ratio Li / TM of 1.02 to obtain a mixture. The mixture was heated to 760°C in a muffle oven and kept for 10 hours under a forced flow of mixed oxygen. After cooling to ambient temperature, the powder was deagglomerated and sieved through a 32 μm mesh to obtain the cathode active material CAM 1. Metallic nickel was no longer detectable.

[0099] The D50 of the electrode active material B-CAM.1 is 11.8 μm, determined using the technique of LASER diffraction on a Mastersize 3000 device from Malvern Instruments. [Explanation of symbols]

[0100] Figure 1: A: Reaction vessel (A), for step (a) B: Reaction vessel (B), for step (b) C: Solid-liquid separation device for separating precursor from mother liquor (liquid phase) D: Drying of filter cake E: Solid-liquid separation to keep unreacted metal in the reaction vessel (B) F: Solid-liquid separation for extraction of liquid phase Figure 2-4: SEM images of p-CAM.1, different scales.

Claims

1. A method for producing particulate (oxy)hydroxides of TM, wherein TM represents a combination of metals, TM comprises nickel and at least one metal selected from cobalt, aluminum, and manganese, and the method comprises the following steps: (a) Combining an aqueous slurry of metallic nickel and at least one metal selected from aluminum and transition metals other than nickel with an oxidizing agent selected from oxygen and nitrates at a temperature of 5°C to 40°C in a first reaction vessel or in a first group of reaction vessels in the presence of ammonia; (b) Transferring the aqueous reaction medium from step (a) to a second reaction vessel containing a slurry of hydroxides of TM, wherein the pH value in step (b) is higher than that in step (a) and the temperature is in the range of 45°C to 80°C, thereby forming and growing particles of hydroxides of TM; (c) Removing the particles from step (b) from the liquid by a solid-liquid separation method and drying the particles; (d) Returning the liquid phase obtained in step (c) to the first reaction vessel A method comprising the above steps.

2. The particulate (oxy)hydroxide is selected from hydroxides and oxyhydroxides of TM, and TM is a combination of metals represented by the general formula (I): (Ni a Co b Mn c ) 1-d M d (I) (wherein a ranges from 0.6 to 0.95, b ranges from 0 to 0.2, c ranges from 0 to 0.2, d ranges from 0 to 0.1, M is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, a + b + c = 1, and c + d > 0) The method according to claim 1.

3. The method according to claim 1 or 2, wherein step (a) is carried out in the presence of a complexing agent selected from ammonia, borate, polyborate, glycine, tartrate, citrate, and oxalate.

4. The method according to claim 1 or 2, wherein M is Al and 0 < c ≤ 0.

1.

5. The method according to claim 1 or 2, wherein between steps (a) and (b), metal particles are removed from the aqueous reaction medium of step (a) by filtration or sedimentation or magnetic separation and returned to the first reaction vessel.

6. Step (b) is carried out in an atmosphere containing O of 500 ppm or less ２ The method according to claim 1 or 2, wherein the method is carried out in an atmosphere containing O of 500 ppm or less

7. The method according to claim 1 or 2, wherein step (a) is carried out in the absence of oxygen.

8. The method according to claim 1 or 2, wherein in step (b), a compound of manganese or aluminum is added.

9. The method according to claim 1 or 2, wherein in step (d), 80 to 95% by volume of the liquid phase from step (c) is returned to the first reaction vessel.

10. The method according to claim 1 or 2, wherein both steps (a) and (b) are carried out without adding an alkali metal hydroxide.

11. The method according to claim 1 or 2, wherein the pH value in step (a) is in the range of 7.0 to 10.0, and the pH value in step (b) is in the range of 9.0 to 13.

0.

12. A particulate (oxy)hydroxide of TM, wherein TM contains nickel and at least one metal selected from cobalt, manganese, and aluminum, and the particulate (oxy)hydroxide of TM further contains 0.1 to 10 mol% of TM metal in a zero oxidation state with respect to TM.

13. The particulate (oxy)hydroxide according to claim 12, containing 0.1 to 10 mol% of a metal in a zero oxidation state with respect to TM, and the metal being nickel.

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