Method for precipitating mixed hydroxides and cathode active materials prepared therefrom

Abstract

A method for precipitating a mixed hydroxide of TM (wherein TM comprises Ni, at least one of Co and Mn, and optionally Al, Mg, Zr, or Ti) from an aqueous solution of a salt of the transition metal, or a salt of Al, or a salt of Mg, the method being carried out in a stirred tank and comprising the steps of introducing an aqueous solution of an alkali metal hydroxide and an aqueous solution of a transition metal salt into the stirred tank through at least two inlets, the distance between the introduction points of the TM salt and the introduction points of the alkali metal hydroxide being no more than six hydraulic diameters from the tip of the inlet for the alkali metal hydroxide.

Description

[Technical Field]

[0001] The present invention is directed to a method for precipitating mixed hydroxides of TM (wherein TM comprises Ni, at least one of Co and Mn, and optionally Al, Mg, Zr, or Ti) from aqueous solutions of salts of the transition metal, Al, or Mg. The method is carried out in a stirred tank and comprises the steps of introducing an aqueous solution of an alkali metal hydroxide and an aqueous solution of a transition metal salt into the stirred tank through at least two inlets, wherein the distance between the introduction points of the TM salt and the introduction points of the alkali metal hydroxide is no more than six times, preferably no more than four times, the hydraulic diameter of the tip of the inlet tube for the alkali metal hydroxide. [Background technology]

[0002] Lithium-ion secondary batteries are state-of-the-art devices for energy storage. Many applications are being considered, ranging from small devices such as mobile phones and laptops to car batteries and other e-mobility batteries. The various components of a battery, such as the electrolyte, electrode materials, and separator, play crucial roles in battery performance. Particular attention has been paid to the positive electrode (cathode) material. Several materials have been proposed, including lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide. Despite extensive research, the solutions found so far still have room for improvement.

[0003] The electrode material is an important factor that determines the performance of lithium-ion batteries. Lithium-containing mixed transition metal oxides are particularly important, such as spinel and layered mixed oxides, especially lithium-containing mixed oxides of nickel, manganese, and cobalt (see, for example, EP 1 189 296). However, not only the stoichiometry of the electrode material but also other properties such as morphology and surface properties are important.

[0004] The corresponding mixed oxides are generally produced using a two-stage process. In the first stage, a sparingly soluble salt of the transition metal(s) is prepared by precipitation from a solution, e.g., of the carbonate or hydroxide. This sparingly soluble salt is often also called a precursor. In the second stage, the precipitated salt of the transition metal(s) is mixed with a lithium compound, e.g., Li2CO3, LiOH, or Li2O, and calcined at high temperatures, e.g., 600-1100 °C.

[0005] Existing lithium-ion batteries still have room for improvement, particularly in terms of energy density. To achieve this, it is desirable for the cathode material to have a high specific capacity. It would also be advantageous if the cathode material could be processed in a simple manner to produce an electrode layer with a thickness of 20 μm to 200 μm. To achieve the maximum energy density (per unit volume), this electrode layer must have high density and high cycle stability.

[0006] WO2012 / 095381 and WO2013 / 117508 disclose processes for precipitating hydroxides or carbonates, which use a vessel with compartments, each of which requires a significant energy input, and which are difficult to implement on a commercial scale. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] EP1189296 [Patent Document 2] WO2012 / 095381 [Patent Document 3] WO2013 / 117508 Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a method for producing a precursor of a positive electrode active material (cathode active material) for a lithium ion battery having a high volumetric energy density and excellent cycle stability. More specifically, an object of the present invention is to provide a battery starting material suitable for producing a lithium ion battery having a high volumetric energy density and excellent cycle stability. A further object of the present invention is to provide a method for producing a starting material suitable for a lithium ion battery.

[0009] Without being bound by any theory, it can be assumed that the lithiation process depends on the particle size, porosity, and specific surface area of the precursor. One object of the present invention is to provide a method for producing a precursor that can be lithiated in a highly efficient manner. More specifically, one object of the present invention is to provide a starting material for a battery that can be lithiated in a highly efficient manner. [Means for solving the problem]

[0010] We have therefore found a method as defined at the outset, which will hereinafter also be referred to as the method of the invention or the method according to the invention. The method of the invention can be carried out as a batch process or as a continuous or semi-continuous process, with a continuous process being preferred. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 shows a stirred vessel of the present invention. [Figure 2] FIG. 2 is a diagram for explaining the radial direction. [Figure 3A] FIG. 3A is an SEM analysis image showing the radial direction and the direction of primary particles in a cross section of a secondary particle of the cathode material CAM.8 of the present invention. [Figure 3B] FIG. 3B is an SEM analysis image of the comparative example cathode material C-CAM.10. [Figure 4]FIG. 4 shows the manganese content of TM-OH.1 in the core and outer surface of the particle as a function of secondary particle size. [Figure 5] FIG. 5 shows the nickel content of TM-OH.1 in the particle core and outer particle surface as a function of secondary particle size. [Figure 6] FIG. 6 shows the manganese content of TM-OH.4 in the core and outer surface of the particle as a function of secondary particle size. [Figure 7] FIG. 7 shows the nickel content of TM-OH.4 in the core and outer surface of the particle as a function of secondary particle size. DETAILED DESCRIPTION OF THE INVENTION

[0012] The process of the present invention is a process for precipitating mixed hydroxides of TM. In the context of the present invention, the term "mixed hydroxide" refers to hydroxides, and includes not only stoichiometrically pure hydroxides but also compounds which, in addition to the transition metal cation and hydroxide ion, also contain anions other than hydroxide, such as oxide and carbonate, or anions derived from transition metal starting materials, such as acetates or nitrates, especially sulfates.

[0013] In one embodiment of the present invention, the mixed hydroxide may contain 0.01 to 45 mol %, preferably 0.1 to 40 mol %, of anions other than hydroxide ions, based on the total number of anions in the mixed hydroxide. In an embodiment using a sulfate as a starting material, for example, 0.001 to 1 mol %, preferably 0.01 to 0.5 mol %, of sulfate may be present as an impurity.

[0014] In the context of the present invention, the TM comprises Ni, at least one of Co and Mn, and optionally Al, Mg, Zr, or Ti. Preferably, the TM is selected from the group consisting of Ni, at least one of Co and Mn, and optionally Al, Mg, Zr, or Ti. Although Al and Mg are not transition metals, in the context of the present invention, the solution of a salt of TM will hereinafter also be referred to as a solution of a transition metal.

[0015] In one embodiment of the present invention, the TM contains a metal of general formula (I): Ni a M 1 b Mn c (I) (In the formula, each symbol is defined as follows: M 1 is Co or a combination of Co and at least one element selected from Ti, Zr, Al, and Mg; a is in the range of 0.15 to 0.95, preferably 0.5 to 0.9, b is in the range of 0 to 0.35, preferably 0.03 to 0.2, c is in the range of 0 to 0.8, preferably 0.05 to 0.65; where a+b+c=1.0 and at least one of b and c is greater than 0).

[0016] M 1 In the embodiment where M is Co and at least one element selected from Ti, Zr, Al, and Mg, 1 Preferably, at least 95 mol % to 99.9 mol % of the total is Co.

[0017] In one embodiment of the present invention, the symbols in formula (I) are defined as follows: a is in the range of 0.8 to 0.95, M 1 is a combination of Co and at least one element selected from Ti, Zr, Al and Mg, and M 1 95 mol % to 99.9 mol % of the b is in the range of 0.03 to 0.2, c is 0, a+b+c=1.0.

[0018] In another embodiment of the present invention, the symbols in formula (I) are defined as follows: a is in the range of 0.6 to 0.95, M 1is Co or a combination of Co and at least one element selected from Ti, Zr, Al and Mg, and M 1 95 mol % to 99.9 mol % of the b is in the range of 0.03 to 0.2, c is in the range of 0.05 to 0.2, a+b+c=1.0.

[0019] In another embodiment of the present invention, the symbols in formula (I) are defined as follows: a is in the range of 0.15 to 0.5, b is 0 to 0.05, c is in the range of 0.55 to 0.8, a+b+c=1.0.

[0020] Many elements are ubiquitous. For example, sodium, copper, and chloride are found in some very small proportion in almost all inorganic substances. In the context of the present invention, the proportion of cations or anions less than 0.02 mol % is disregarded. Therefore, mixed hydroxides containing less than 0.02 mol % sodium obtained according to the method of the present invention are considered to be sodium-free in the context of the present invention.

[0021] According to one embodiment of the present invention, the method of the present invention is a method for precipitating a mixed hydroxide having an average particle size (D50) determined by laser diffraction in the range of 2 to 20 μm, preferably 2 to 16 μm, and more preferably 9 to 16 μm.

[0022] The process of the present invention is carried out in a stirred tank, which may be a stirred tank reactor or a continuous stirred tank reactor, which may be selected from stirred tank reactors forming part of a cascade of stirred tank reactors, for example a cascade of two or more, in particular two or three, stirred tank reactors.

[0023] In carrying out the process of the present invention, an aqueous solution of an alkali metal hydroxide and an aqueous solution of a transition metal are introduced into the stirred vessel.

[0024] In the context of the present invention, nickel, one of manganese and cobalt, and optionally Al 3+ or Mg 2+ Aqueous solutions with at least one cation such as are also called "aqueous solutions of transition metal salts" for short.

[0025] The aqueous solution of transition metal salts comprises a nickel salt and a cobalt salt and / or a manganese salt. Suitable examples of nickel salts include, in particular, water-soluble nickel salts, i.e., nickel salts having a solubility in distilled water determined at 20° C. of at least 25 g / l, preferably 50 g / l. Suitable salts of nickel, cobalt and manganese include, in each case, for example, carboxylates, in particular acetates, of nickel, cobalt and manganese, as well as sulfates, nitrates, halides, in particular bromides or chlorides of nickel, cobalt and manganese, where nickel is Ni +2 Cobalt exists as Co +2 manganese exists as Mn +2 where Ti and / or Zr, where applicable, are present in the +4 oxidation state, and aluminum is present in the +3 oxidation state and can be introduced, for example, as sodium aluminate or aluminum acetate or sulfate.

[0026] The aqueous solution of transition metal salts can contain at least one additional transition metal salt, preferably two or three additional transition metal salts, in particular salts of two or three transition metals, or salts of cobalt and aluminum. Suitable transition metal salts are especially water-soluble salts of the transition metal(s), i.e., salts having a solubility in distilled water of at least 25 g / l, preferably 50 g / l, determined at room temperature (20°C). Suitable transition metal salts, especially salts of cobalt and manganese, are, for example, carboxylates, especially acetates, as well as sulfates, nitrates, halides, especially bromides or chlorides, of the transition metal(s), in which the transition metal(s) are preferably present in the +2 oxidation state. Such solutions preferably have a pH value in the range of 1 to 5, more preferably in the range of 2 to 4.

[0027] In one embodiment of the invention, it is possible to proceed from an aqueous solution of a transition metal salt which, in addition to water, contains one or more organic solvents, such as ethanol, methanol or isopropanol, for example up to 15% by volume relative to the water, or in another embodiment of the invention, from an aqueous solution of a transition metal salt which contains less than 0.1% by weight of an organic solvent relative to the water, or preferably no organic solvent.

[0028] According to one embodiment of the present invention, the aqueous solution of transition metal salt used comprises ammonia, an ammonium salt, or one or more organic amines, such as methylamine or ethylenediamine. Preferably, the aqueous solution of transition metal salt comprises less than 10 mol % of ammonia or organic amines, based on the transition metal M. In a particularly preferred embodiment of the present invention, the aqueous solution of transition metal salt does not comprise any appreciable proportion of ammonia or organic amines.

[0029] Preferred ammonium salts include, for example, ammonium sulfate and ammonium sulfite.

[0030] The aqueous solution of transition metal salts may have a total concentration of the transition metal(s) in the range of, for example, 0.01 to 4 mol / l, preferably 1 to 3 mol / l, based on the solution.

[0031] In one embodiment of the present invention, the molar ratio of transition metals in an aqueous solution of transition metal salts is adjusted to the desired stoichiometry in the mixed transition metal oxide used as a cathode material or precursor. It may also be necessary to consider that the solubilities of various transition metal carbonates may differ.

[0032] The aqueous solution of the transition metal salt may contain one or more additional salts in addition to the counterion of the transition metal salt. These salts are preferably salts that do not form sparingly soluble salts with M, or bicarbonates of, for example, sodium, potassium, magnesium, or calcium. In the latter case, a change in pH may cause precipitation of the carbonate. An example of such a salt is ammonium sulfate.

[0033] In another embodiment of the invention, the aqueous solution of the transition metal salt does not contain any additional salts.

[0034] In one embodiment of the invention, the aqueous solution of the transition metal salt may contain one or more additives selected from biocides, complexing agents such as ammonia, chelating agents, surfactants, reducing agents, carboxylic acids and buffers, hi another embodiment of the invention, the aqueous solution of the transition metal salt does not contain any additives.

[0035] Specific examples of suitable reducing agents that may be present in the aqueous solution of the transition metal salt include sulfites, especially sodium sulfite, sodium bisulfite (NaHSO), potassium sulfite, potassium bisulfite, ammonium sulfite, as well as hydrazine and salts of hydrazine, such as the hydrogen sulfate of hydrazine, and water-soluble organic reducing agents, such as ascorbic acid or aldehydes.

[0036] The alkali metal hydroxide can be selected from the hydroxides of lithium, rubidium, cesium, potassium and sodium and combinations of at least two of the foregoing, with potassium, sodium and combinations of the foregoing being preferred, and sodium being more preferred. The aqueous solution of alkali metal hydroxide may have a hydroxide concentration in the range of 0.1 to 12 mol / l, preferably 6 to 10 mol / l.

[0037] The aqueous alkali metal hydroxide solution used in the process of the present invention may contain one or more further salts, such as ammonium salts, in particular ammonium hydroxide, ammonium sulfate or ammonium sulfite. In one embodiment, the molar ratio of NH3:transition metal may be set to between 0.01 and 0.9, more preferably between 0.05 and 0.65.

[0038] In one embodiment of the present invention, the aqueous solution of alkali metal hydroxide can contain ammonia or one or more organic amines, such as methylamine. Preferably, there are no measurable amounts of organic amines present.

[0039] In one embodiment of the present invention, the aqueous solution of alkali metal hydroxide may contain some carbonate or bicarbonate. Technical grade potassium hydroxide usually contains some potassium (bi)carbonate, and technical grade sodium hydroxide usually contains some sodium (bi)carbonate. Regardless of the alkali metal (bi)carbonate content, in the context of the present invention, each technical grade alkali metal hydroxide will be referred to as "alkali metal hydroxide" for short.

[0040] The process of the present invention is carried out in a stirred tank, such as a stirred tank reactor, or a continuous stirred tank reactor, or a cascade of at least two continuous stirred tank reactors, for example, a cascade of 2 to 4 continuous stirred tank reactors. Preferably, the process of the present invention is carried out in a continuous stirred tank reactor. The continuous stirred tank reactor contains at least one overflow system, which allows for continuous or interval withdrawal of slurry from the continuous stirred tank reactor.

[0041] The method of the present invention includes a step of introducing an aqueous solution of an alkali metal hydroxide and an aqueous solution of a transition metal salt into the stirred tank through at least two inlets (inlet ports), wherein the distance between the introduction point of the transition metal salt and the introduction point of the alkali metal hydroxide is 6 times or less, preferably 4 times or less, and more preferably 2 times or less the hydraulic diameter of the tip of the inlet pipe for the alkali metal hydroxide. This step is also referred to as the "introduction step."

[0042] In the context of the present invention, the expression "tip of the inlet" refers to the point where the alkali metal hydroxide or transition metal solution exits the respective inlet.

[0043] The hydraulic diameter is defined as four times the cross-sectional area of the tip of the inlet divided by the wetting parameter of the tip of the inlet.

[0044] In one embodiment of the present invention, the aqueous solution of an alkali metal hydroxide and the aqueous solution of a transition metal salt are introduced into a stirred tank through two inlets, for example, through two conduits (pipes) arranged side by side, for example, with their outlets adjacent to each other, or through a Y-shaped mixer.

[0045] In a preferred embodiment of the present invention, the at least two inlets are designed as a coaxial mixer comprising two conduits arranged coaxially for introducing the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt into the stirred tank. In one embodiment of the present invention, the introducing step is carried out by using two or more conduits arranged coaxially for introducing the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt into the stirred tank. In another embodiment of the present invention, the introducing step is carried out using exactly one system of conduits arranged coaxially for introducing the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt into the stirred tank.

[0046] Furthermore, it is more preferable that the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt are introduced into the stirred tank through two inlets, and in this case, it is more preferable that the two inlets are designed as a coaxial mixer.

[0047] Although it is possible to introduce a portion of the aqueous solution of alkali metal hydroxide and a portion of the aqueous solution of transition metal salt at different locations, e.g., up to 30% of the aqueous solution of alkali metal hydroxide and up to 30% of the aqueous solution of transition metal salt, it is preferred to introduce all of the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt through the conduits arranged as described above.

[0048] In one embodiment of the present invention, the point (location) where the aqueous solution of the transition metal salt and the aqueous solution of the alkali metal hydroxide are introduced is below (below) the liquid level in the stirred vessel, while in another embodiment of the present invention, the point (location) where the aqueous solution of the transition metal salt and the aqueous solution of the alkali metal hydroxide are introduced is above (above) the liquid level in the stirred vessel.

[0049] In the course of the introducing step of the preferred embodiment, the aqueous solution of the alkali metal hydroxide can be introduced from one of the conduits of the coaxially arranged mixer, and the aqueous solution of the transition metal salt can be introduced from the other of the conduits of the coaxially arranged mixer.

[0050] In one embodiment of the present invention, the speed at which the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt are introduced is in the range of 0.01 to 10 m / s. 3 In the above stirring tank, the speed is preferably 0.5 to 5 m / s.

[0051] In a preferred embodiment of the present invention, the aqueous solution of the transition metal salt is introduced through the inner conduit (inner tube) of the coaxial mixer, and the aqueous solution of the alkali metal hydroxide is introduced through the outer conduit (outer tube), but in this case, slight incrustations may occur.

[0052] In one embodiment of the present invention, the inner conduit of the coaxial mixer has an inner diameter ranging from 1 mm to 120 mm, preferably from 5 mm to 50 mm, depending on the size of the vessel used. The larger the vessel, the larger the diameter of the tip of the inlet.

[0053] In one embodiment of the present invention, the outer conduit of the coaxial mixer has an inner diameter in the range of 1.5 to 10 times, preferably 1.5 to 6 times, the inner diameter of the inner conduit.

[0054] Preferably, the conduit has a circular cross section.

[0055] In one embodiment of the invention, the walls of the conduit have a thickness in the range of 1 to 10 mm.

[0056] The conduit can be made of steel, stainless steel, or steel coated with PTFE (polytetrafluoroethylene), FEP (fluorinated ethylene-propylene copolymer), or PFA (perfluoroalkoxy polymer), with stainless steel being preferred.

[0057] In one embodiment of the present invention, the conduit of the coaxial mixer is bent. In a preferred embodiment of the present invention, the conduit of the coaxial mixer is not bent.

[0058] The coaxial mixer can function as a coaxial nozzle.

[0059] In one embodiment of the present invention, the point where the aqueous solution of the transition metal salt and the aqueous solution of the alkali metal hydroxide are introduced is above the liquid level (liquid surface), for example, by 3 to 50 cm. In a preferred embodiment of the present invention, the point where the aqueous solution of the transition metal salt and the aqueous solution of the alkali metal hydroxide are introduced is below the liquid level, for example, by 5 to 30 cm, preferably by more than 10 cm and at most 20 cm.

[0060] In one embodiment of the present invention, the pH value at the tip of the outlet of said at least two inlets is in the range of 11-15, preferably in the range of 12-14.

[0061] In one embodiment of the present invention, the tips of the at least two injection ports are located outside the vortex generated by stirring in the stirred tank.

[0062] In some embodiments, particularly if the degree of turbulence at the outlets of the at least two inlets is too low, precipitates of mixed metal (oxy)hydroxides may form at the outlet of the coaxial mixer, which may then form deposits. In a preferred embodiment of the present invention, at regular time intervals, the at least two inlets, preferably the coaxial mixer, are flushed with water to physically remove the deposits of transition metal (oxy)hydroxides. The time intervals may occur, for example, every 2 minutes up to every hour, and the rinsing period may last from 1 second to 5 minutes, preferably from 1 second to 30 seconds. It is preferable to keep the intervals between rinsing as short as possible to avoid unnecessary dilution of the reaction medium. In one embodiment of the present invention, the water may contain ammonia to maintain a pH value above 7.

[0063] In one embodiment of the present invention, the stirring tank is charged with water or an aqueous solution of ammonia, an ammonium salt, or an alkali metal salt before the start of the introducing step. In a preferred embodiment of the present invention, the stirring tank is charged with an aqueous medium containing at least one of the above components and having a pH value in the range of 10 to 13.

[0064] The above-mentioned stirred vessel may further comprise one or more pumps, inserts, mixing units, baffles, wet mills, homogenizers, and a stirred tank that serves as an additional compartment for sedimentation. This stirred tank preferably has a much smaller volume than the first-mentioned stirred vessel. Particularly suitable pumps include centrifugal pumps and peripheral wheel pumps.

[0065] However, in preferred embodiments of the present invention, such stirred tanks do not include separate compartments, external loops, or additional pumps.

[0066] In one embodiment of the present invention, the process according to the present invention can be carried out at a temperature in the range of 20 to 90° C., preferably 30 to 80° C., more preferably 35 to 75° C. This temperature is measured in a stirred tank.

[0067] The method according to the invention can be carried out in air, in an inert gas atmosphere, such as a noble gas or nitrogen atmosphere, or in a reducing gas atmosphere, such as CO and SO. Preference is given to working in an inert gas atmosphere.

[0068] In one embodiment of the present invention, the aqueous solution of the transition metal and the aqueous solution of the alkali metal hydroxide have a temperature in the range of 10 to 75°C before being contacted in the stirred tank.

[0069] The stirred tank is equipped with an agitator. Suitable agitators are selected from pitch blade turbines, Rushton turbines, cross-arm agitators, dissolver blades, and propeller agitators. The agitator can be operated at a rotation speed that results in an average energy input in the range of 0.1 to 10 W / l, preferably in the range of 1 to 7 W / l.

[0070] In embodiments where the stirred tank is a continuous stirred-tank reactor or a cascade of at least two stirred-tank reactors, each stirred-tank reactor(s) has an overflow system. The slurry contains the precipitated mixed metal hydroxide of TM and a mother liquor. In the present invention, the mother liquor comprises water-soluble salts and, optionally, further additives present in solution. Specific examples of possible water-soluble salts include alkali metal salts of transition metal counterions, such as sodium acetate, potassium acetate, sodium sulfate, potassium sulfate, sodium nitrate, potassium nitrate, sodium halides, potassium halides, etc., as well as corresponding ammonium salts, such as ammonium nitrate, ammonium sulfate, and / or ammonium halides. Most preferably, the mother liquor comprises sodium sulfate, ammonium sulfate, and ammonia.

[0071] In one embodiment of the present invention, the process is carried out in a vessel equipped with a clarifier, where the mother liquor is separated from the precipitated mixed metal hydroxides of TM and recovered.

[0072] The method of the present invention forms an aqueous slurry from which particulate mixed hydroxides can be obtained through solid-liquid separation processes such as filtration, spray drying, drying under inert gas or air, etc. Drying in air causes partial oxidation to yield mixed oxyhydroxides of TM.

[0073] The precursors obtained according to the method of the present invention are excellent starting materials for cathode active materials suitable for producing batteries with maximum volumetric energy density.

[0074] It has been found that by carrying out the method of the present invention, it is possible to achieve a bulk nickel and manganese concentration, preferably at the expense of Mn, that allows Ni to accumulate not only in the cores of secondary particles but also in large secondary particles, regardless of their size. This characteristic remains in the positive electrode active material produced from the precursor prepared according to the present invention, even after calcination. Without wishing to be bound by theory, it is assumed that these characteristics contribute to the excellent cycle stability.

[0075] A further aspect of the present invention relates to a precursor for a lithium-ion battery. Such a precursor is also referred to as the precursor of the present invention hereinafter. The precursor of the present invention is a particulate transition metal (oxy)hydroxide represented by the general formula (II): Ni a M 1 b Mn c O x (OH) y (CO3) t (II) (In the formula, each symbol is defined as follows: M 1 is Co or a combination of Co and at least one metal selected from Ti, Zr, Al, and Mg; a is in the range of 0.15 to 0.95, preferably 0.5 to 0.9, b is in the range of 0 to 0.35, preferably 0.03 to 0.2, c is in the range of 0 to 0.8, preferably 0.05 to 0.65, where a + b + c = 1.0, and at least one of b and c is greater than 0, 0 ≦ x < 1, 1 < y ≦ 2.2, and 0 ≦ t ≦ 0.3) where the secondary particles are aggregates of primary particles essentially oriented in the radial direction.

[0076] In one embodiment of the present invention, the symbols in formula (II) are defined as follows: a is in the range of 0.8 to 0.95, M 1 is a combination of Co and at least one element selected from Ti, Zr, Al, and Mg, and M 1 is 95 mol% to 99.9 mol% Co, b is in the range of 0.03 to 0.2, c is 0, a + b + c = 1.0.

[0077] In another embodiment of the present invention, the symbols in formula (II) are defined as follows: a is in the range of 0.6 to 0.95, M 1 is Co or a combination of Co and at least one element selected from Ti, Zr, Al, and Mg, and M 1 is 95 mol% to 99.9 mol% Co, b is in the range of 0.03 to 0.2, c is in the range of 0.05 to 0.2, a + b + c = 1.0.

[0078] In another embodiment of the present invention, the symbols in formula (II) are defined as follows: a is in the range of 0.15 to 0.5, b is 0 to 0.05, c is in the range of 0.55 to 0.8, u a + b + c = 1.0.

[0079] The primary particles may be needle-shaped, platelet-shaped, or a mixture of both. The term "radially oriented" refers to the length of needles, or the length or width of platelets, being oriented in the radial direction of the respective secondary particles.

[0080] The proportion of radially oriented primary particles can be determined, for example, by SEM (scanning electron microscopy) of cross sections of at least five secondary particles.

[0081] The term "essentially radially oriented" does not necessarily mean that the particles are completely radially oriented, but includes a deviation of up to 11 degrees, preferably up to 5 degrees, from a completely radially oriented state as determined by SEM analysis.

[0082] Furthermore, at least 60% of the volume of the secondary particles is filled with radially oriented primary particles, and preferably only a small portion of the volume of the particles, e.g., at most 40%, preferably at most 20%, is filled with non-radially oriented, e.g., randomly oriented, primary particles.

[0083] The particulate transition metal (oxy)hydroxide of the present invention has a total pore / intrusion volume in the range of 0.033 to 0.1 ml / g, preferably 0.035 to 0.07 ml / g, in the pore diameter range of 20 to 600 Å (determined by N adsorption according to DIN 66134 (1998) when the sample for N adsorption measurement is prepared by degassing at 120°C for 60 minutes).

[0084] In a preferred embodiment, the particulate transition metal (oxy)hydroxide of the present invention has an average pore diameter in the range of 100 to 250 Å, as measured by N 2 adsorption.

[0085] In one embodiment of the present invention, the particulate transition metal (oxy)hydroxide of the present invention has an average secondary particle size D50 in the range of 2 to 20 μm, preferably 2 to 16 μm, and more preferably 10 to 16 μm.

[0086] In one embodiment of the present invention, the precursor of the present invention is 2 to 70 m 2 / g, preferably 4 to 50m 2 / g, which can be determined by nitrogen adsorption after outgassing the sample at 200°C for 30 minutes or more according to DIN ISO 9277:2010.

[0087] In one embodiment of the present invention, the precursor of the present invention has a particle size distribution, [(D90)-(D10)] divided by (D50), in the range of 0.5 to 1.1.

[0088] The precursor obtained by the method of the present invention is an excellent starting material for a cathode active material suitable for the production of batteries with high volumetric energy density and excellent cycling stability. Such a cathode active material is produced by mixing the precursor with a lithium source, such as LiO, LiOH, or LiCO, in an anhydrous or hydrated state, and calcining the mixture at a temperature ranging from 600 to 1000°C. Therefore, a further aspect of the present invention is the use of the precursor of the present invention for producing a cathode active material for a lithium-ion battery. Another aspect of the present invention is a method for producing a cathode active material for a lithium-ion battery (hereinafter also referred to as the calcination method of the present invention), which comprises mixing the particulate transition metal (oxy)hydroxide according to any one of claims 11 to 14 with a lithium source and heat-treating the mixture at a temperature ranging from 600 to 1000°C. In this method, the ratio of the precursor of the present invention to the lithium source is preferably selected so that the molar ratio of Li to TM is in the range of 0.95:1 to 1.2:1.

[0089] A specific example of the firing of the present invention is heat treatment carried out at a temperature in the range of 600 to 900° C., preferably 650 to 850° C. In the context of the present invention, the terms “thermally treat” and “heat treatment” are used synonymously and interchangeably.

[0090] In one embodiment of the present invention, the mixture obtained by the firing of the present invention is heated to 600 to 900°C at a heating rate of 0.1 to 10°C / min.

[0091] In one embodiment of the present invention, the temperature is increased until a desired temperature of 600 to 900° C., preferably 650 to 800° C. is reached. For example, the mixture obtained in step (d) is first heated to a temperature of 350 to 550° C., and then kept constant for 10 minutes to 4 hours. Thereafter, the temperature is increased to 650 to 800° C., and then kept at 650 to 800° C. for 10 minutes to 10 hours.

[0092] In one embodiment of the present invention, the firing of the present invention is carried out in a roller hearth kiln, a pusher kiln, or a rotary kiln, or a combination of at least two of these. Rotary kilns have the advantage that the material produced therein is very well homogenized. In roller hearth kilns and pusher kilns, different reaction conditions for different processes can be set very easily. Laboratory-scale tests can also be carried out in box furnaces, tube furnaces, and split-tube furnaces.

[0093] In one embodiment of the present invention, the calcination of the present invention is carried out in an oxygen-containing atmosphere, such as a nitrogen-air mixture, a noble gas-oxygen mixture, air, oxygen, or oxygen-enriched air. In a preferred embodiment, the atmosphere in step (d) is selected from air, oxygen, and oxygen-enriched air. The oxygen-enriched air may be, for example, a 50:50 volumetric mixture of air and oxygen. Other examples include a 1:2 volumetric mixture of air and oxygen, a 1:3 volumetric mixture of air and oxygen, a 2:1 volumetric mixture of air and oxygen, and a 3:1 volumetric mixture of air and oxygen.

[0094] In one embodiment of the present invention, the calcination of the present invention is carried out under a flow of gas, such as air, oxygen, and oxygen-enriched air. This gas flow is sometimes called a forced gas flow. The gas flow is represented by the general formula Li 1+x TM 1-x 0.5 to 15 m per kg of material expressed as O2 3 The volume is determined at standard conditions, i.e., 298 Kelvin and 1 atmosphere. The gas flow is useful for removing gaseous cleavage products such as water and carbon dioxide.

[0095] In one embodiment of the present invention, the firing of the present invention has a duration ranging from 1 hour to 30 hours, preferably from 10 hours to 24 hours. For the time at temperatures above 600°C, the heating and holding time counts, but the cooling time is ignored here.

[0096] Another aspect of the present invention is a compound of the general formula Li 1+X TM 1-X O2 (wherein x is in the range of −0.05 to 0.2, and TM is a compound represented by the formula (I) Ni a M 1 b Mn c (I) (In the formula, each symbol is defined as follows: M 1 is Co or a combination of Co and at least one metal selected from Ti, Zr, Al, and Mg; a is in the range of 0.15 to 0.95, b is in the range of 0 to 0.35, c is in the range of 0 to 0.8, a+b+c=1.0, and at least one of b and c is greater than 0) (containing a metal represented by Regarding the positive electrode active material represented by The positive electrode active material is composed of secondary particles, which are agglomerates of primary particles, and at least 50% by volume of the secondary particles are agglomerates of primary particles that are essentially radially oriented.

[0097] In a preferred embodiment, in the positive electrode active material of the present invention, the nickel content in the core of the secondary particles is higher than that at the outer surface, preferably by 1 to 10 mol %, and the nickel content is higher in larger secondary particles than in smaller secondary particles, preferably at the expense of Mn.

[0098] In one embodiment of the present invention, in the cathode active material of the present invention, more than 50% of the primary particles exhibit an orientation that deviates from perfect radial orientation by at most 11 degrees, and 80% of the primary particles exhibit an orientation that deviates from perfect radial orientation by at most 34 degrees.

[0099] In a preferred embodiment, in the positive electrode material of the present invention, the value obtained by dividing [(D90)-(D10)] by (D50) of the secondary particles is in the range of 0.4 to 2.

[0100] In a preferred embodiment, in the positive electrode material of the present invention, the value obtained by dividing [(D90)-(D10)] by (D50) of the primary particles is in the range of 0.5 to 1.1.

[0101] In a preferred embodiment, the positive electrode active material of the present invention has a median primary axis ratio (median primary axis ratio) of greater than 1.5.

[0102] The invention is further explained by means of two figures, examples and further graphs.

[0103] Brief description of the drawings, Figure 1: A: Mixing tank (container) B: Stirrer C: Wall of the inner conduit (inner pipe) of the coaxial mixer D: Wall of the outer pipe (outer pipe) of the coaxial mixer E: Baffle F: Stirrer engine. [Example]

[0104] Overview: Analysis of nickel concentration was performed using cross-sectional SEM images by energy dispersive X-ray spectroscopy (EDS).

[0105] The proportion and degree of radial orientation of the primary particles was determined as follows.

[0106] All identified primary particles were segmented from the SEM images of the cross section of the cathode material, unless the surface could not be clearly identified for technical reasons, and further analysis was performed (schematically shown in Figure 3). From the segmented primary particles, descriptive parameters for each particle, such as primary particle size, primary particle axial ratio, and primary particle orientation, were calculated as follows.

[0107] The distribution of each of these quantities for all identified primary particles defines distribution parameters such as the mean, median, standard deviation, and percentile of each quantity for the material.

[0108] The primary particle size was calculated as the diameter of a circle covering the same area in the image as the particle.

[0109] The axial ratio of a primary particle was calculated by dividing the particle's length by its width, where length and width are defined by the long and short sides of the minimum bounding box for each particle, i.e., the smallest rectangle enclosing the primary particle.

[0110] The above-described determination method is also an aspect of the present invention.

[0111] Figure 2 is a diagram for explaining the radial direction. Brief explanation of Figure 2 (each symbol has the following meaning): A: Secondary particles B: Primary particle C: Center of secondary particle D: Center of primary particle E: Radial direction (defined as the direction from the center of the secondary particle to the center of the primary particle) F: Primary particle orientation (defined as the orientation of the eigenvector with the largest eigenvalue of the covariance matrix calculated for the binary mask of the primary particles) G: The angle between the orientation of the primary particles and the ideal radial direction.

[0112] For each primary particle, determine the smallest absolute angle (G) between the radial direction (E) and the long axis direction (F) of the primary particle. Therefore, an angle of 0 indicates that the primary particle is ideally radially aligned, while a larger angle indicates a less ideal radial alignment. The distribution of angles G for each primary particle quantitatively indicates the degree of radial alignment throughout the sample. In the case of perfect radial alignment, the distribution is zero. In the case of completely random alignment, the angles are uniformly distributed between 0 and 90 degrees, with a median angle (center value of the angle) and mean angle (average value of the angle) of 45 degrees.

[0113] Figure 3A is an SEM analysis image showing the radial direction and primary particle direction in the cross section of a secondary particle of the cathode material CAM.8 of the present invention, and Figure 3B is an SEM analysis image of a comparative cathode material C-CAM.10.

[0114] I. Precursor Preparation The aqueous solution of (NH4)2SO4 used in the examples contained 26.5 g of (NH4)2SO4 per kg of aqueous solution.

[0115] Examples 1-4 were carried out in a 10 L stirred vessel (also referred to as the "vessel" in these examples) equipped with baffles, a 0.14 m diameter cross-arm stirrer, and a coaxial mixer (see Figure 1). The coaxial mixer was positioned within the vessel so that its outlet was approximately 5 cm below the liquid surface. The coaxial mixer consisted of two coaxially arranged stainless steel conduits. The inner circular conduit had an inner diameter of 3 mm and an outer diameter of 6 mm. The outer circular conduit had an inner diameter of 8 mm and an outer diameter of 12 mm.

[0116] I.1 Preparation of precursor TM-OH.1 Eight liters of the (NH4)2SO4 aqueous solution was placed in a container, and the pH of the solution was adjusted to 11.5 using a 25% by mass aqueous solution of sodium hydroxide.

[0117] The vessel temperature was set to 45°C. The stirrer element was activated and operated constantly at 530 rpm (average input power: 6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 6:2:2, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit (inner tube) of the coaxial mixer, and the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit (outer tube) of the coaxial mixer. The distance between the outlets of the two coaxially arranged conduits was within 5 mm.

[0118] The molar ratio of ammonia to metal was adjusted to 0.3. The total volumetric flow rate was set to adjust the average residence time to 6 hours. The flow rate of NaOH was also adjusted by a pH control circuit to maintain a constant pH value of 11.5 in the stirred tank. The apparatus was operated continuously while maintaining a constant liquid level in the vessel. The mixed hydroxide of Ni, Co, and Mn was allowed to freely overflow from the vessel and collected. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, and its average particle size (D50) was 9.6 μm (TM-OH.1). The tap density of the precursor of the present invention, TM-OH.1, was 1.95 g / L and the BET specific surface area was 14.1 m. 2 / g. The total pore volume was 0.056 ml / g, and the average pore diameter was 161.6 Å. At least 70% of the secondary particle volume of the precursor of the present invention consisted of essentially radially oriented primary particles. The smaller the individual secondary particles, the lower the nickel content. Furthermore, the outer surface of the particles contained an average of 4.5% less nickel than the particle core. Meanwhile, the manganese concentration was an average of 5.9% higher at the outer surface of the particles compared to the particle core, although the small secondary particles contained more manganese than the large secondary particles (see Figures 4 and 5). This data was obtained by EDS measurements on SEM cross-section micrographs.

[0119] TM-OH.1 was found to be highly suitable as a precursor for positive electrode active materials for lithium-ion batteries.

[0120] Figure 4: Manganese content of TM-OH.1 in the particle core and outer surface as a function of secondary particle size. Manganese content was determined by EDS measurements on SEM particle cross sections.

[0121] Figure 5: Nickel content of TM-OH.1 in the particle core and outer particle surface as a function of secondary particle size. Manganese content was determined by EDS measurements on SEM particle cross sections.

[0122] I.2 Preparation of precursor TM-OH.2 Eight liters of the (NH4)2SO4 aqueous solution was placed in a container, and the pH of the solution was adjusted to 12.05 using a 25% by mass aqueous solution of sodium hydroxide.

[0123] The vessel temperature was set to 45°C. The stirrer element was turned on and operated constantly at 530 rpm (average input power ~6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 6:2:2, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit of the coaxial mixer, while the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 7 mm.

[0124] The molar ratio of ammonia to metal was adjusted to 0.3. The total volumetric flow rate was set to adjust the average residence time to 6 hours. The flow rate of NaOH was also adjusted by a pH control circuit to maintain a constant pH value of 12.05 in the vessel. The apparatus was operated continuously while maintaining a constant liquid level in the reaction vessel. The mixed hydroxide of Ni, Co, and Mn was allowed to freely overflow from the vessel and collected. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 10.5 μm (TM-OH.2). The tap density of the precursor of the present invention, TM-OH.2, was 2.07 g / L and the BET specific surface area was 12.48 m. 2 The total pore volume was 0.044 ml / g, and the average pore diameter was 141.5 Å. At least 70% of the secondary particle volume of TM-OH.2 consisted of essentially radially oriented primary particles. TM-OH.2 was highly suitable as a precursor for cathode active materials for lithium-ion batteries.

[0125] I.3 Preparation of precursor TM-OH.3 Eight liters of the (NH4)2SO4 aqueous solution was placed in a container, and the pH of the solution was adjusted to 12.05 using a 25% by mass aqueous solution of sodium hydroxide.

[0126] The vessel temperature was set to 45°C. The stirrer element was turned on and operated constantly at 530 rpm (average input power ~6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 6:2:2, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit of the coaxial mixer, while the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 7 mm.

[0127] The molar ratio of ammonia to metal was adjusted to 0.35. The total volumetric flow rate was set to adjust the average residence time to 6 hours. The flow rate of NaOH was also adjusted by a pH control circuit to maintain a constant pH value of 12.05 in the stirred tank. The apparatus was operated continuously while maintaining a constant liquid level in the reactor. The mixed hydroxide of Ni, Co, and Mn was collected by free overflow from the reactor. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 9.8 μm (TM-OH.3). The tap density of TM-OH.3 was 2.0 g / L, and the BET specific surface area was 11.3 m. 2 The total pore volume of TM-OH.3 was 0.037 ml / g, and the average pore diameter was 132.0 Å. At least 70% of the secondary particle volume of TM-OH.3 consisted of essentially radially oriented primary particles. TM-OH.3 was highly suitable as a precursor for cathode active materials for lithium-ion batteries.

[0128] I.4 Preparation of precursor TM-OH.4 Eight liters of the (NH4)2SO4 aqueous solution was placed in a container, and the pH of the solution was adjusted to 11.5 using a 25% by mass aqueous solution of sodium hydroxide.

[0129] The vessel temperature was set to 55°C. The stirrer element was turned on and operated constantly at 530 rpm (average input power: ~6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 87:5:8, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit of the coaxial mixer, while the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 5 mm.

[0130] The molar ratio of ammonia to metal was adjusted to 0.2. The total volumetric flow rate was set to adjust the average residence time to 6 hours. The flow rate of NaOH was also adjusted using a pH control circuit to maintain a constant pH value of 11.5 in the vessel. The apparatus was operated continuously while maintaining a constant liquid level in the vessel. The mixed hydroxide of Ni, Co, and Mn was collected by freely overflowing from the vessel. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, and its average particle size (D50) was 12.3 μm (TM-OH.4). The tap density of TM-OH.4 was 1.91 g / L, and the BET specific surface area was 17.94 m. 2 / g. The total pore volume of TM-OH.4 was 0.045 ml / g, and the average pore diameter was 106.3 Å. At least 70% of the secondary particle volume of TM-OH.4 consisted of essentially radially oriented primary particles.

[0131] Furthermore, the outer surfaces of the secondary particles contained an average of 3.7% less nickel than the particle core. Meanwhile, manganese concentrations were on average 4.9% higher at the particle surfaces compared to the particle core, although smaller secondary particles contained more manganese than larger secondary particles (see Figures 6 and 7). This data was obtained by EDS measurements on SEM cross-section micrographs.

[0132] TM-OH.4 was found to be highly suitable as a precursor for positive electrode active materials for lithium-ion batteries.

[0133] I.5 Preparation of precursor TM-OH.5 A 50 L stirred vessel (see Figure 1) equipped with a baffle, a 0.21 m diameter cross-arm stirrer, and a coaxial mixer was charged with 40 L of the above (NH4)2SO4 aqueous solution. The pH of the solution was then adjusted to 11.6 using a 25% by weight aqueous solution of sodium hydroxide. The coaxial mixer was positioned within the vessel so that its outlet was approximately 10 cm below the liquid surface. The coaxial mixer consisted of two coaxially arranged stainless steel conduits. The inner circular conduit had an inner diameter of 1 mm and an outer diameter of 4 mm. The outer circular conduit had an inner diameter of 2 mm and an outer diameter of 6 mm.

[0134] The vessel temperature was set to 55°C. The stirrer element was activated and operated continuously at 420 rpm (average input power: 12.6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 83:12:5, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit of the coaxial mixer, while the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 15 mm.

[0135] The molar ratio of ammonia to metal was adjusted to 0.265. The total volumetric flow rate was set to adjust the average residence time to 5 hours. The flow rate of NaOH was also adjusted by a pH control circuit to maintain a constant pH value of 11.58 in the vessel. The apparatus was operated continuously while maintaining a constant liquid level in the vessel. The mixed hydroxide of Ni, Co, and Mn was collected by free overflow from the vessel. The resulting product slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 10.5 μm (TM-OH.5). The tap density of TM-OH.5 was 1.95 g / L and the BET specific surface area was 23.1 m. 2The total pore volume of TM-OH.5 was 0.074 ml / g, and the average pore diameter was 127.7 Å. At least 70% of the secondary particle volume of TM-OH.5 consisted of essentially radially oriented primary particles. TM-OH.5 was highly suitable as a precursor for cathode active materials for lithium-ion batteries.

[0136] I.6 Preparation of precursor TM-OH.6 A 50 L stirred vessel (see Figure 1) equipped with a baffle, a 0.21 m diameter cross-arm stirrer, and a coaxial mixer was charged with 40 L of the above (NH4)2SO4 aqueous solution. The pH of the solution was then adjusted to 11.9 using a 25% by weight aqueous solution of sodium hydroxide. The coaxial mixer was positioned within the vessel so that its outlet was approximately 10 cm below the liquid surface. The coaxial mixer consisted of two coaxially arranged stainless steel conduits. The inner circular conduit had an inner diameter of 1 mm and an outer diameter of 4 mm. The outer circular conduit had an inner diameter of 2 mm and an outer diameter of 6 mm.

[0137] The vessel temperature was set to 55°C. The stirrer element was activated and operated continuously at 420 rpm (average input power: 12.6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 83:12:5, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit of the coaxial mixer, while the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 30 mm.

[0138] The molar ratio of ammonia to metal was adjusted to 0.265. The total volumetric flow rate was set to adjust the average residence time to 5 hours. The flow rate of NaOH was also adjusted by a pH control circuit to maintain a constant pH value of 11.9 in the vessel. The apparatus was operated continuously while maintaining a constant liquid level in the reactor. The mixed hydroxide of Ni, Co, and Mn was collected by free overflow from the vessel. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 12.3 μm (TM-OH.6). The tap density of TM-OH.6 was 1.93 g / L, and the BET specific surface area was 20.91 m. 2 The total pore volume of TM-OH.6 was 0.066 ml / g, and the average pore diameter was 126.2 Å. At least 70% of the secondary particle volume of TM-OH.6 consisted of essentially radially oriented primary particles. TM-OH.6 was highly suitable as a precursor for cathode active materials for lithium-ion batteries.

[0139] I.7 Preparation of precursor TM-OH.7 A 50 L stirred vessel (see Figure 1) equipped with a baffle, a 0.21 m diameter cross-arm stirrer, and a coaxial mixer was charged with 40 L of the above (NH4)2SO4 aqueous solution. The pH of the solution was then adjusted to 11.9 using a 25% by weight aqueous solution of sodium hydroxide. The coaxial mixer was positioned within the vessel so that its outlet was approximately 10 cm below the liquid surface. The coaxial mixer consisted of two coaxially arranged FEP conduits. The inner circular conduit had an inner diameter of 1.5 mm and an outer diameter of 3.2 mm. The outer circular conduit had an inner diameter of 4 mm and an outer diameter of 6 mm.

[0140] The temperature of the vessel was set to 55°C. The stirrer element was turned on and operated constantly at 420 rpm (average input power 12.6 W / L). An aqueous solution of NiSO4, CoSO4, and MnSO4 (molar ratio 83:12:5, total transition metal concentration: 1.65 mol / kg), an aqueous sodium hydroxide solution (25% by mass NaOH), and an aqueous ammonia solution (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced from the inner conduit of the coaxial mixer, and the aqueous sodium hydroxide solution and the aqueous ammonia solution were introduced from the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 30 mm.

[0141] The molar ratio of ammonia to metal was adjusted to 0.265. The total volumetric flow rate was set to adjust the average residence time to 5 hours. The flow rate of NaOH was also adjusted using a pH control circuit to maintain a constant pH value of 11.9 in the vessel. The apparatus was operated continuously while maintaining a constant liquid level in the reactor. The mixed hydroxide of Ni, Co, and Mn was collected by freely overflowing from the vessel. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 12.3 μm (TM-OH.7). The tap density of TM-OH.7 was 1.93 g / L, and the BET specific surface area was 21.3 m. 2 The total pore volume of TM-OH.7 was 0.066 ml / g, and the average pore diameter was 126.2 Å. At least 70% of the secondary particle volume of TM-OH.7 consisted of essentially radially oriented primary particles. TM-OH.7 was highly suitable as a precursor for cathode active materials for lithium-ion batteries.

[0142] I.8 Preparation of precursor TM-OH.8 A 50 L stirred vessel (see Figure 1) equipped with a baffle, a 0.21 m diameter cross-arm stirrer, and a coaxial mixer was charged with 40 L of the (NH4)2SO4 aqueous solution. The pH of the solution was then adjusted to 11.88 using a 25% by weight aqueous solution of sodium hydroxide. The coaxial mixer was positioned within the vessel so that its outlet was approximately 10 cm below the liquid surface. The coaxial mixer consisted of two coaxially arranged FEP conduits. The inner circular conduit had an inner diameter of 1.5 mm and an outer diameter of 3.2 mm. The outer circular conduit had an inner diameter of 4 mm and an outer diameter of 6 mm.

[0143] The vessel temperature was set to 55°C. The stirrer element was activated and operated continuously at 420 rpm (average input power: 12.6 W / L). Aqueous solutions of NiSO4, CoSO4, and MnSO4 (molar ratio 83:12:5, total metal concentration: 1.65 mol / kg), aqueous sodium hydroxide (25% by mass NaOH), and aqueous ammonia (25% by mass ammonia) were simultaneously introduced into the vessel through a coaxial mixer. The aqueous metal solution was introduced through the inner conduit of the coaxial mixer, while the aqueous sodium hydroxide and ammonia solutions were introduced through the outer conduit of the coaxial mixer. The distance between the outlets of the two conduits arranged coaxially was within 30 mm.

[0144] The molar ratio of ammonia to metal was adjusted to 0.265. The total volumetric flow rate was set to adjust the average residence time to 5 hours. The flow rate of NaOH was also adjusted by a pH control circuit to maintain a constant pH value of 11.9 in the vessel. The apparatus was operated continuously while maintaining a constant liquid level in the reactor. The mixed hydroxide of Ni, Co, and Mn was collected by free overflow from the vessel. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 12.0 μm (TM-OH.8). The tap density of TM-OH.8 was 1.92 g / L, and the BET specific surface area was 20.58 m. 2 / g. At least 70% of the secondary particle volume of TM-OH.8 consisted of essentially radially oriented primary particles. TM-OH.8 was highly suitable as a precursor for cathode active materials for lithium-ion batteries.

[0145] I.9 Comparative Example - Preparation of Comparative Precursor C-TM-OH.9 A 50 L stirred vessel (see Figure 1) equipped with baffles, a 0.21 m diameter cross-arm stirrer, and a coaxial mixer was charged with 40 L of the above aqueous (NH)SO solution. The pH of the solution was then adjusted to 11.4 using a 25% by weight aqueous solution of sodium hydroxide. In this experiment, no feed material was added via the coaxial mixer. Instead, the transition metal feed was added via a 4 mm internal diameter dipped pipe located near the stirrer element, and NaOH and ammonia were added via another 4 mm internal diameter dipped pipe located near the stirrer element. The outlets of both pipes were more than 10 times the inner hydraulic diameter of the alkali-addition pipe.

[0146] The temperature of the vessel was set to 55°C. The stirrer element was started and operated constantly at 420 rpm (average input power 12.6 W / L). An aqueous solution of NiSO4, CoSO4 and MnSO4 (molar ratio 83:12:5, total metal concentration: 1.65 mol / kg), an aqueous sodium hydroxide solution (25% by weight NaOH) and an aqueous ammonia solution (25% by weight ammonia) were introduced simultaneously.

[0147] The molar ratio of ammonia to transition metals was adjusted to 0.115. The total volumetric flow rate was set to adjust the average residence time to 5 hours. The flow rate of NaOH was also adjusted using a pH control circuit to maintain a constant pH of 11.4 in the vessel. The reactor was operated continuously while maintaining a constant liquid level in the reactor. The mixed hydroxide of Ni, Co, and Mn was allowed to freely overflow and collected. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 10.2 μm (C-TM-OH.9). C-TM-OH.9 was used as a precursor for a comparative lithium-ion battery cathode active material.

[0148] I.10 Comparative Example - Preparation of Comparative Precursor C-TM-OH.10 A 50 L stirred vessel (see Figure 1) equipped with baffles, a 0.21 m diameter cross-arm stirrer, and a coaxial mixer was charged with 40 L of the above aqueous (NH)SO solution. The pH of the solution was then adjusted to 12.34 using a 25% by weight aqueous solution of sodium hydroxide. In this experiment, no feed was added via a coaxial mixer. Instead, the transition metal feed was added via a 4 mm internal diameter submerged conduit located near the stirrer element, and NaOH and ammonia were added via separate 4 mm internal diameter submerged conduits located near the stirrer element. The outlets of both conduits were separated by more than 10 hydraulic diameters inside the alkali feed conduit.

[0149] The temperature of the vessel was set to 55 °C. The stirrer element was activated and operated constantly at 420 rpm (average input power ∼12.6 W / L). An aqueous metal solution containing NiSO4, CoSO4, and MnSO4 (molar ratio 87:5:8, total metal concentration: 1.65 mol / kg), an aqueous sodium hydroxide solution (25% by weight NaOH), and an aqueous ammonia solution (25% by weight ammonia) were simultaneously introduced.

[0150] The molar ratio of ammonia to metal was adjusted to 0.4. The total volumetric flow rate was set to adjust the average residence time to 5 hours. The flow rate of NaOH was also adjusted using a pH control circuit to maintain a constant pH value of 12.34 in the vessel. The reactor was operated continuously while maintaining a constant liquid level in the reactor. The mixed hydroxide of Ni, Co, and Mn was allowed to freely overflow and collected. The resulting slurry contained approximately 120 g / L of mixed hydroxide of Ni, Co, and Mn, with an average particle size (D50) of 13.0 μm (C-TM-OH.10). C-TM-OH.10 was used as a precursor for a comparative lithium-ion battery cathode active material.

[0151] II. Production of the Positive Electrode Active Material of the Present Invention II.1 Preparation of the Cathode Material CAM.1 of the Present Invention Using TM-OH.1 The precursor TM-OH.1 was mixed with LiOH monohydrate and crystalline Al2O3 such that the Al concentration relative to Ni+Co+Mn+Al was 0.3 mol % and the Li / (Ni+Co+Mn+Al) molar ratio was 1.02. The resulting mixture was heated to 820 °C and held for 8 hours under forced oxygen flow. After natural cooling, the resulting calcined powder was de-agglomerated and sieved through a 32 μm vibrating screen. This yielded the cathode active material CAM.1.

[0152] The first discharge of CAM.1 at 0.1 C measured in a half cell reached 187.0 mAh / g. After 100 cycles in a half cell, the capacity reached 99.8%.

[0153] II.2 Preparation of the cathode material CAM.4 of the present invention using TM-OH.4 The precursor TM-OH.4 was mixed with LiOH monohydrate and crystalline Al2O3 such that the Al concentration relative to Ni+Co+Mn+Al was 0.3 mol % and the Li / (Ni+Co+Mn+Al) molar ratio was 1.02. The resulting mixture was heated to 820 °C and held for 5 hours under forced oxygen flow. After natural cooling, the resulting calcined powder was deagglomerated and sieved through a 32 μm vibrating screen. This yielded the cathode active material CAM.4.

[0154] The first discharge of CAM.4 at 0.1 C measured in a half cell reached 186.0 mAh / g. After 100 cycles in a half cell, the capacity reached 98.5%.

[0155] II.3 Preparation of the cathode material CAM.5 of the present invention using TM-OH.5 The precursor TM-OH.5 was mixed with LiOH monohydrate at a molar ratio of Li / (Ni+Co+Mn+Al) of 1.02. The resulting mixture was heated to 760°C and held for 6 hours under forced oxygen flow. After natural cooling, the resulting calcined powder was deagglomerated and sieved through a 32 μm vibrating screen. This yielded the cathode active material CAM.5.

[0156] The median primary particle diameter was 0.24 μm, the span was 0.92, and the median axis ratio was 1.88.

[0157] The orientation of 20% of the primary particles of CAM.5 deviated from the ideal radial orientation by 2.8 degrees or less, 50% by 10.5 degrees or less, and 80% by less than 10.5 degrees. An exemplary micrograph of an SEM cross section of CAM.5 of the present invention is shown in Figure 3B.

[0158] The first discharge capacity of CAM.5 at 0.1C measured in a half cell reached 205.8mAh / g, and the capacity after 50 and 100 full cell cycles at 1C reached 97.9% and 90.6%, respectively.

[0159] II.4 Preparation of the cathode material CAM.8 of the present invention using TM-OH.8 The precursor TM-OH.8 was mixed with LiOH monohydrate, TiO2, and Zr(OH)4 such that the Zr concentration was 0.17 mol % and the Ti concentration was 0.17 mol % relative to Ni+Co+Mn+Zr+Ti, resulting in a Li / (Ni+Co+Mn+Zr+Ti) molar ratio of 1.05. The mixture was heated to 780°C and held for 6 hours under forced oxygen flow. After natural cooling, the resulting calcined powder was deagglomerated and sieved through a 32 μm vibrating screen. This yielded the cathode active material CAM.8.

[0160] The median primary particle diameter was 0.37 μm, the span was 1.10, and the median axial ratio was 1.56. 20% of the primary particles were oriented with an angle of 4.3° or less from the ideal radial orientation, 50% with an angle of 10.7° or less, and even 80% with an angle of 31.0° or less.

[0161] The first discharge capacity of CAM.8 at 0.1C measured in a half cell reached 204.7mAh / g, and the capacity after 50 and 100 full cell cycles at 1C reached 96.3% and 94.1%, respectively.

[0162] II.5 Comparative Example—Preparation of Cathode Material C-CAM.10 Using C-TM-OH.10 The precursor TM-OH.10 was mixed with LiOH monohydrate, TiO2, and Zr(OH)4 such that the Zr concentration was 0.17 mol % and the Ti concentration was 0.17 mol % relative to Ni+Co+Mn+Zr+Ti, resulting in a Li / (Ni+Co+Mn+Zr+Ti) molar ratio of 1.04. The resulting mixture was heated to 760°C and held for 5 hours under forced oxygen flow. After natural cooling, the resulting calcined powder was deagglomerated and sieved through a 32 μm vibrating screen. This resulted in the cathode active material C-CAM.10.

[0163] The median primary particle size was 0.27 μm, the span was 1.27, and the median axial ratio was 1.44. An exemplary micrograph of the SEM cross section of the comparative positive electrode active material C-CAM.10 is shown in FIG. 3A. The orientation of 20% of the primary particles deviated by 9.0 degrees or less from the ideal radial orientation, 50% by 20.3 degrees or less, and 80% by 45.0 degrees or less. The first discharge capacity of C-CAM.10 at 0.1C measured in a half cell reached 203.7mAh / g, and the capacity after 50 and 100 full cell cycles at 1C reached 94.2% and 86.5%, respectively.

[0164] III. Electrochemical Testing Percentages are by weight unless otherwise specified. For the positive electrode, the percentages refer to the entire positive electrode minus the current collector.

[0165] III.1 Cathode Fabrication Electrode Fabrication: Each electrode contained 93% of each cathode active material, 1.5% carbon black (Super C65), 2.5% graphite (SFG6L), and 3% binder (polyvinylidene fluoride, Solef 5130). The slurry was mixed with N-methyl-2-pyrrolidone and cast onto aluminum foil with a doctor blade. Each electrode was dried at 105 °C in a vacuum for 6 hours, after which a circular electrode was punched out, weighed, and dried at 120 °C in a vacuum overnight before being placed in an Ar-filled glove box.

[0166] III.2 Electrolyte (electrolyte) Electrolyte 1: 1 M LiPF6 in ethylene carbonate (EC):dimethyl carbonate (DMC) (1:1 mass ratio) was used as the electrolyte.

[0167] Electrolyte 2: 1M LiPF in EC:ethyl methyl carbonate (EMC) (1:1 mass ratio) (containing 2% vinylene carbonate by mass) III.3 Negative electrode (anode) 0.58mm thick Li foil.

[0168] III.3 Manufacturing of half-cell coin cells A coin-type electrochemical cell was assembled in an argon-filled glove box. A 14 mm diameter positive electrode (loading 11.0 0.4 mg cm) was used. -2 The negative electrode was separated from the positive electrode by a glass fiber separator (Whatman GF / D). 100 μl of electrolyte 1 was used in the half-cell.

[0169] Testing was performed using a Maccor 4000 system. Constant-current cycling was performed between 3 and 4.3 V vs. Li, followed by potentiostatic cycling at 4.3 V for 30 minutes or until the current fell below 0.01 C. The cell was placed in a Binder climate chamber at a constant temperature of 25°C. The cell was cycled for 129 cycles. First, the cycle tests were performed at a 0.1C / 0.1C (charge / discharge, the same applies below) rate for two cycles to measure the capacity; then, at a 0.1C / 0.1C rate for five cycles to condition; then, at rates of 0.5C / 0.1C, 0.5C / 0.2C, 0.5C / 0.5C, 0.5C / 1C, 0.5C / 2C, and 0.5C / 3C for six cycles to measure the discharge rate capacity; then, at a 0.5C / 0.1C rate for two cycles to measure the capacity; at a 0.5C / 0.1C rate for 50 cycles to evaluate the cycle stability; at a 0.5C / 0.1C rate for two cycles to evaluate the capacity; at a 0.5C / 0.1C rate for 50 cycles to evaluate the cycle stability; at a 0.5C / 0.1C rate for two cycles to evaluate the capacity; and finally, at a 0.5C / 0.1C rate for 10 cycles to evaluate the cycle stability.

[0170] III.4 Full-cell coin cell manufacturing Full-cell electrochemical measurements: A coin-type electrochemical cell was assembled in an argon-filled glove box. The positive electrode (17.5 mm in diameter, 11.3 mg / cm) had a loading of 1.1 mg / cm. -2The negative electrode and 18.5 mm graphite electrode were separated by a glass fiber separator (Whatman GF / D). A volume of 300 μl of electrolyte 2 was used. Each cell was galvanostatically cycled between 2.7 and 4.20 V at a 1 C rate at 45 °C, followed by a potentiostatic charge step at 4.2 V for 1 hour or until the current fell below 0.02 C using a Maccor 4000 battery cycling machine.

[0171] During resistance measurements (performed every 25 cycles at 25°C), the cell was charged in the same manner as the cycles. The cell was then discharged at 1 C for 30 minutes to reach a 50% state of charge. This was followed by a 30-second open-circuit step to equilibrate the cell. Finally, a 2.5 C discharge current was applied for 30 seconds and the resistance was measured. At the end of the current pulse, the cell was again equilibrated at open circuit for 30 seconds and then further discharged at 1 C to 2.7 V (vs. graphite).

[0172] To calculate the resistance, the voltage V0s before applying the 2.5C pulse current, the voltage V10s after applying the 2.5C pulse current for 10 seconds, and the 2.5C current value (I (unit: ampere A)) were measured. The resistance was calculated according to the following formula 1 (S: electrode area, V: voltage, I: 2.5C pulse current).

[0173] R=(V0s-V10s) / I*S (Formula 1)

Claims

1. 1. A method for precipitating a mixed hydroxide of TM (wherein TM comprises Ni, at least one of Co and Mn, and optionally Al, Mg, Zr, or Ti) from an aqueous solution of a salt of a transition metal, an Al salt, or an Mg salt, the method being carried out in a stirred tank and comprising the steps of introducing an aqueous solution of an alkali metal hydroxide and an aqueous solution of a transition metal salt into the stirred tank through at least two inlets, the distance between the introduction point of the TM salt and the introduction point of the alkali metal hydroxide being not more than six times the hydraulic diameter of the tip of the inlet for the alkali metal hydroxide.

2. 2. The method according to claim 1, wherein the at least two inlets are designed as a coaxial mixer comprising two conduits arranged coaxially, through which the aqueous solution of alkali metal hydroxide and the aqueous solution of TM salt are introduced into the stirred tank.

3. 3. The method according to claim 1, wherein the introduction points of the aqueous solution of metal salt and the aqueous solution of alkali metal hydroxide are below the liquid level in the stirred tank.

4. 3. The method according to claim 1, wherein the introduction points of the aqueous solution of metal salt and the aqueous solution of alkali metal hydroxide are above the liquid level in the stirred tank.

5. 5. The method according to claim 2, wherein the metal salt solution is introduced through an inner conduit of the coaxial mixer, and the alkali metal hydroxide solution is introduced through an outer conduit.

6. The method according to any one of claims 1 to 5, wherein the aqueous solution of alkali metal hydroxide contains ammonia.

7. The method of any one of claims 1 to 6, wherein the stirred vessel is a continuous stirred tank reactor.

8. 8. The method according to claim 1, wherein at least two inlets are designed as a coaxial mixer, and the coaxial mixer is washed with water at regular intervals to physically remove deposits of transition metal (oxy)hydroxides.

9. 9. The method according to claim 1, wherein the speed at which the aqueous solution of alkali metal hydroxide and the aqueous solution of transition metal salt are introduced is in the range of 0.01 to 10 m / s.

10. TM is a compound of formula (I) Ni ａ M １ ｂ Mn ｃ (I) (wherein each symbol is defined as follows: M １ is Co or a combination of Co and at least one metal selected from Ti, Zr, Al, and Mg; a is in the range of 0.15 to 0.95; b is in the range of 0 to 0.35; c is in the range of 0 to 0.8; a + b + c = 1.0, and at least one of b and c is greater than 0. The method according to any one of claims 1 to 9, containing a metal represented by

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