Method for producing particulate (oxy) hydroxides of nickel and metals other than nickel

Abstract

A process for preparing a particulate (oxy) hydroxide of TM wherein TM is a combination of nickel and at least one metal selected from Co and Mn, and wherein said method comprises the following steps: (a) by mixing one or more aqueous solutions (alpha) containing Ni and sulfates of at least one transition metal selected from Co and Mn and optionally of at least one additional metal selected from Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta, and an aqueous solution (beta) containing sodium hydroxide and optionally an aqueous solution (gamma) containing a complexing agent in a stirred tank reactor The present invention relates to a method for producing sodium sulfate, comprising the following steps: (a) separating the TM hydroxide from the continuous phase, combining and precipitating the hydroxide of TM, (b) separating the precipitated TM hydroxide from the continuous phase by a filtration step, followed by washing the resulting filter cake with an aqueous medium, thereby obtaining a washed filter cake and a filtrate containing sodium sulfate, (c) removing water from the filtrate, thereby obtaining a concentrated filtrate and water, (d) at least partially recycling the water from step (d) and using it as (e1) filtering the wash water in step (c), (e2) the reaction medium in step (a), or (e3) at least part of the process water.

Description

[0001] The present invention relates to a process for preparing particulate (oxy)hydroxides of a TM, wherein TM is a combination of nickel and at least one metal selected from the group consisting of Co and Mn, and wherein TM is defined according to general formula (I):

[0002] (Ni a Co b Mn c ) 1-d M d (I)

[0003] wherein

[0004] a is in the range of 0.25 to 0.98,

[0005] b is 0 or in the range of 0.02 to 0.2,

[0006] c is in the range of 0 to 0.75, and

[0007] d is in the range of 0 to 0.1, and

[0008] a + b + c = 1, and b + c > 0,

[0009] M is selected from the group consisting of Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta, and combinations of at least two of the foregoing,

[0010] and wherein the process comprises the following steps:

[0011] (a) precipitating a hydroxide of TM by combining in a stirred tank reactor one or more aqueous solutions (a) containing sulphates of Ni and at least one transition metal selected from the group consisting of Co and Mn, and optionally at least one further metal selected from the group consisting of Ti, Zr, Mo, W, Al, Sb, Mg, Sb, Nb and Ta, and an aqueous solution (b) containing sodium hydroxide, and optionally an aqueous solution (g) containing a complexing agent,

[0012] (b) separating the precipitated TM hydroxide from the continuous phase by a filtration step, thereby obtaining a washed filter cake and a filtrate containing sodium sulphate,

[0013] (c) subsequently washing the resulting filter cake with an aqueous medium, thereby obtaining a washed filter cake and a washing filtrate containing sodium sulphate,

[0014] (d) removing water from the washing filtrate, thereby obtaining a concentrated filtrate,

[0015] (e) at least partially recycling the water from step (d) and using it as at least a portion of

[0016] (e1) the aqueous medium used for washing in filtration step (c), or

[0017] (e2) the reaction medium in step (a), or

[0018] (e3) process water.

[0019] Lithiated transition metal oxides are currently used as electrode active materials for lithium ion batteries. In the past years, a lot of research and development work has been performed to improve characteristics like charge density, specific energy and also other characteristics that can negatively influence the lifetime or suitability of lithium ion batteries like cycle life reduction and capacity loss. Additional efforts have been made to improve the manufacturing process.

[0020] In a typical process for preparing a cathode material for lithium ion batteries, a so-called precursor is first formed by co-precipitation of the transition metals as carbonates, oxides or, preferably, as hydroxides which can or can not be basic (e.g. oxyhydroxides). The precursor is then mixed with a lithium source like, but not limited to, LiOH, Li2O or Li2CO3 and calcined at high temperature. The lithium source(s) can be used as hydrate(s) or in dehydrated form. The calcination - or firing, also often referred to as thermal or heat treatment of the precursor - is usually performed at temperatures in the range of 600 °C to 1,000 °C. During the heat treatment, the electrode active material is formed. The heat treatment is performed in the heating zone of an oven or kiln.

[0021] One class of typical cathode active materials providing high energy density contains a high amount of Ni (Ni-rich), e.g. at least 80 mol-% relative to the content of non-lithium metals. Another class of typical cathode active materials exhibiting high energy density are so-called manganese-rich materials, e.g. disclosed in WO 2021 / 037678. However, especially in batch-type battery material precursor manufacturing processes, a morphology gradient in the precursor and the resulting cathode active material has been observed, which has a negative impact on the electrochemical performance. Furthermore, the processes to manufacture such materials and especially their precursors usually generate a large amount of waste water.

[0022] It is still an object to provide cathode active materials with excellent electrochemical performance and to provide a process for manufacturing such cathode active materials, including their precursors.

[0023] It was found that by using an improved water management in the precursor production process, an improved precursor impurity profile can be obtained. The impurities are in particular referring to sulphate that can be incorporated by the co-precipitation process. Especially it was found that the sodium sulphate concentration in the mother liquor leads to an adverse sulphate gradient over the particle radius.

[0024] Accordingly, the method as defined at the outset, hereinafter also referred to as the inventive method, has been found. The inventive method comprises the steps (a) to (e), hereinafter also referred to as step (a) or simply (a), step (b) or simply (b), etc. The inventive method will be described in more detail hereinafter.

[0025] Step (a) comprises combining an aqueous solution containing a sulfate of nickel and at least one metal selected from cobalt and manganese with an aqueous solution of sodium hydroxide, optionally in the presence of a complexing agent, preferably ammonia or a salt of ammonia.

[0026] The relative amounts of nickel to the at least one metal selected from cobalt and manganese can be chosen in a wide range. Nickel can be present in an amount of 25 to 98 mol-%, excluding alkali metals. Cobalt can be absent or present and can be present in an amount of 1 to 20 mol-%, preferably 3 to 12 mol-%, excluding alkali metals. Manganese can be absent or present and can be present in an amount of 1 to 75 mol-%, preferably 2 to 68 mol-%, excluding alkali metals. Further metals which can be present in step (a) are magnesium or aluminum, for example up to 2 mol-% of magnesium or up to 10 mol-% of aluminum. When aluminum is present in an amount of 3 to 10 mol-%, it is preferred that cobalt is also present.

[0027] During step (a), co-precipitation takes place.

[0028] In one embodiment of the present application, at least one of MgS04, AI2(S04)3, NaAI(OH)4, NaAI(S04)2or KAI(S04)2is introduced so that at least one of aluminum or magnesium is included in the precipitation in step (a).

[0029] Sodium hydroxide is able to absorb carbon dioxide from air and industrial grade sodium hydroxide often contains some sodium carbonate, for example up to 0.5 % by weight, preferably 0.1 % to 0.4 % by weight. By applying such industrial grade sodium hydroxide, mixed hydroxide / carbonate precipitates, but they are also included in the definition of hydroxide.

[0030] In one embodiment of the present application, in step (a), the stoichiometric ratio of sodium hydroxide to the sum of nickel and other metals is about 2:1. In this context, the term "about" means a deviation of the hydroxide content of ± 2 mol-% from the ratio corresponding to the exact stoichiometric ratio. In the presence of a dopant such as aluminum, the amount of hydroxide can vary also depending on the nature of the aluminum source and depending on the amount of complexing agent, for example ammonia.

[0031] In one embodiment of the present application, in step (a) a complexing agent selected from the group consisting of ammonia, glycine, tartrate, citrate and oxalate is used. In the context of the present application, the term glycine includes the compound glycine and its alkali metal salts, such as potassium or, preferably, sodium salts. The terms tartrate and oxalate include the corresponding free acids as well as mono- and di-alkali metal salts, such as mono- or di-potassium salts or mono- or di-sodium salts or mixed sodium and potassium salts. The term "citrate" includes citric acid and its alkali metal salts, such as mono- or di- or tri-sodium salts.

[0032] Preferably a complexing agent is used in step (a) and the most economically advantageous complexing agent is ammonia, which can be used directly or in the form of an ammonium salt, such as ammonium sulfate. Ammonia is formed upon neutralization with a hydroxide.

[0033] The preferred molar ratio of ammonia to TM (metal other than alkali metal) is in the range of 1 : 10 to 1 : 1, more preferably 1 : 8 to 1 : 2.

[0034] The mixed metal hydroxide is precipitated by combining an aqueous solution containing a sulfate of nickel and at least one metal selected from the group consisting of cobalt and manganese with an aqueous solution of sodium hydroxide or sodium carbonate in the presence of ammonia or an ammonia salt. The mixed metal hydroxide is suspended (slurried) in a continuous phase containing sodium sulfate, and traces of nickel and additionally transition metal salts or excess sodium hydroxide and ammonia.

[0035] In one embodiment of the present application, step (a) is carried out at a temperature in the range of 15 °C to 80 °C, preferably 40 °C to 70 °C.

[0036] Step (a) is preferably carried out together with a mixing operation, such as stirring.

[0037] In step (a), a slurry of the precipitated mixed metal hydroxide of TM (nickel and at least one metal selected from the group consisting of cobalt and manganese) is obtained, which can or can not contain at least one dopant selected from the group consisting of Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta.

[0038] In one embodiment of the present application, step (a) is carried out at a pH in the range of 10 to 13, preferably 10.5 to 12.5. The pH is determined at 23 °C and refers to the continuous phase.

[0039] In one embodiment of the present application, the concentration of the mixed metal hydroxide can be increased by carrying out step (a) in a stirred vessel connected to a solid-liquid separation device like a clarifier (e.g. a lamellar clarifier) or a candle filter or a thickener. Through such a solid-liquid separation device, the continuous phase can be removed from the stirred vessel. The thus removed continuous phase is preferably combined with the filtrate from step (b). Such a continuous phase can contain 5 to 20% by weight of Na2SO4.

[0040] In step (b), the precipitated hydroxides of nickel and at least one metal selected from cobalt and manganese are removed by filtration. The filtration can be carried out batchwise or continuously, e.g. with a filter, in particular with a filter press or a belt filter or by suction filtration. A filter press is preferred.

[0041] By filtration, a filter cake and a filtrate containing sodium sulfate are obtained. The concentration of sodium sulfate in the filtrate resulting from step (b) is rather high, e.g. in the range of 5 to 20% by weight of Na2SO4.

[0042] In step (c), the filter cake is washed with an aqueous medium, e.g. with water or an aqueous sodium hydroxide solution. The aqueous medium used for washing can contain some sodium sulfate, e.g. 50 to 1,000 ppm. After washing, the washing filtrate can then be combined with the filtrate from step (b) and preferably with the continuous phase removed in step (a) by the solid-liquid separation device like a lamellar clarifier or a thickener or a candle filter. In other embodiments, the filtrate from step (c) is not combined with the filtrate from step (b). More preferably, the filtrate from step (c) is not combined with the filtrate from step (b) nor with the continuous phase removed in step (a).

[0043] In one embodiment of the present application, the filtrate from step (c) can contain 1 to 5% by weight of Na2SO4. In other embodiments, the washing filtrate can contain 50 to 10,000 ppm of Na2SO4, ppm referring to ppm by weight. The pH value of the filtrate can be in the range of 7 to 14, preferably 8 to 10.

[0044] In another embodiment of step (c), the pH value of the filtrate from step (c) has a pH value in the range of 10 to 14.5, preferably 11.1 to 14.0.

[0045] In one embodiment of step (c), the filter cake from step (c) is pre-dried by blowing a gas, e.g. nitrogen or air, through the filter cake.

[0046] In the subsequent steps, the term filtrate refers to the filtrate from step (c) with or preferably without the filtrate from step (b).

[0047] In one embodiment of step (c), the pH value of the combined filtrate and the liquid phase withdrawn in step (a) has a pH value in the range of 10 to 13.5, preferably 11.1 to 12.5.

[0048] In step (d), water is removed from the combined filtrate from step (c) and the liquid phase withdrawn in step (a) or from the combined filtrate from step (c) and at least a portion of the filtrate from step (b) or preferably only from the filtrate from step (c). The water removal can be performed by reverse osmosis. Reverse osmosis comprises the step of passing the filtrate from step (c) along a porous membrane, e.g. a nanomembrane having a pore width of 2 nm or less, at a pressure of up to 160 bar, preferably up to 120 bar.

[0049] The porous membrane can be composed of a polymer, e.g. PES, PTFE, PVDF, PE, PP. In another embodiment, the porous membrane can be made of a ceramic material like AI2O3, TiO2, ZrO2, SiC or sintered metal. More preferred ceramic membranes are made of AI2O3.

[0050] The polymer or ceramic membrane preferably has pores with an average diameter of 2 nm to 3 pm, preferably 20 to 400 nm and more preferably 50 to 100 nm.

[0051] To enhance the abrasion resistance of the ceramic membrane, a porous membrane comprising two or three membrane layers can be used, e.g. 800 nm, then 400 nm and finally 100 nm, or 400 nm, then 200 nm and finally 100 nm, and more preferably 400 nm, 200 nm and 50 nm.

[0052] The temperature in the reverse osmosis step is preferably in the range of 20 °C to 35 °C. By reverse osmosis, a permeate is obtained which is almost pure water. In addition, the retentate can comprise at least 160 g / l of sodium sulfate, which corresponds to at least 15 wt.-%. It is preferred that there is at least 225 g / l of sodium sulfate, which corresponds to 18.8 wt.-%. A feasible upper limit is 30 % by weight. Reverse osmosis is used to remove water and to increase the concentration of sodium sulfate in the retentate. The water can then be used as reaction medium in step (a) of the process of the present application, and thus, the water is then recycled for another step (a).

[0053] In one embodiment, wherein step (d) is performed by reverse osmosis, the obtained permeate can contain 0.2 % or less of sodium sulfate by weight.

[0054] In one embodiment of the present application, reverse osmosis is performed in at least two (e.g. 2 to 10) stages and the respective membranes are arranged in rows and columns. Possible arrangements of one or more membranes are spiral wound and hollow fiber arrangements, but preferred are disc and tube designs. Spiral wound arrangements are preferred at pressures up to 120 bar.

[0055] Furthermore, by performing step (d), a concentrated filtrate (retentate) and a permeate are obtained. The permeate can be used as recycle water.

[0056] In one embodiment of the present application, a part of the concentrated filtrate from step (d) is treated by ammonia stripping, followed by ultrafiltration of any transition metal oxide precipitate and removal of sodium sulfate. The method of removal is electrodialysis and especially crystallization of Na2S04, e.g. by evaporation crystallization. Water distilled during evaporation crystallization can also be condensed and recycled, before or after mixing with water obtained in step (d).

[0057] In one embodiment of the present application, the mother liquor withdrawn in step (a) is subjected to separate reverse osmosis by a solid-liquid separation device. Examples of such devices are clarifiers, thickeners or candle filters, especially lamellar clarifiers and thickeners. The resulting permeate can then be combined with the permeate from step (d).

[0058] While steps (a) and (b) can be performed continuously or batchwise, water removal in step (d) is preferably operated continuously and under steady state.

[0059] In step (e), the water obtained from step (d) is recycled by using it as at least a part of

[0060] (e1) the water in filtration step (c) or

[0061] (e2) the reaction medium in step (a) or

[0062] (e3) process water.

[0063] Preferably, the water obtained from step (d) is used as the water in filtration step (c) or the reaction medium in step (a) without dilution with fresh water.

[0064] In an alternative version of step (c), the water from step (d) and fresh water can be used in a volume range of 10:1 to 1:10.

[0065] In one embodiment of step (e1) or (e2), the recycled water from step (d) is diluted with fresh water in a ratio of 1:10 to 10:1, respectively, for use as the wash water in step (c) or the reaction medium in step (a). Fresh water in this context means water that has not yet been subjected to the treatment of steps (a) to (d).

[0066] In one embodiment of step (e2), the recycling water from step (d) is diluted with fresh water in a ratio of 1 :10 to 10:1 for the production of one or more of the aqueous solution (a) or the aqueous solution (β).

[0067] In the context of the present invention, process water (e3) is defined as any aqueous medium in steps other than the co-precipitation step (a), where a small amount of sodium sulfate can be tolerated. Examples are water used for purging the reaction vessel of step (a), the initial charge of the reaction vessel before the start of the co-precipitation, water used for cleaning of piping and filter units, etc.

[0068] In one embodiment of the present invention, the sulfate content of the washing water before the start of step (b) or the sulfate content of the reaction medium at the start of step (a) is up to 2% by weight.

[0069] In one embodiment of the present invention, a part of the mother liquor withdrawn during step (a) by the solid-liquid separation device is mixed with the concentrated filtrate from step (d) and optionally with the main filtrate from step (b), and wherein the resulting mixture is separated into a concentrated stream and water in another apparatus similar to step (d), and wherein at least a part of the water obtained is used similar to step (e). Said steps are also referred to as steps (f) and (g), respectively.

[0070] By carrying out the method of the present invention, a precursor for a cathode active material for lithium ion batteries can be produced with minimal fresh water consumption.

[0071] It has been found that by carrying out the process of the present invention, a particulate precursor of a cathode active material is obtained, which particulate precursor has a novel sulfate distribution over the radius of the respective particle. The sulfate is distributed in a gradient over the particle radius, wherein the sulfate concentration in the outer sphere of the particle is at most 2.0 times higher than the sulfate concentration in the core. In the reference process, without carrying out the process of the present invention, the sulfate gradient is more pronounced. A further aspect of the present invention is therefore a particulate (oxy)hydroxide or oxide of TM, wherein TM is a combination of nickel with at least one metal selected from the group consisting of cobalt and manganese, wherein the particulate (oxy)hydroxide has a median particle size (d50) in the range of 2 to 20 pm, and wherein the sulfate is distributed in a gradient over the particle radius, wherein the sulfate concentration in the outer sphere of the particle is at most 2.0 times higher than the sulfate concentration in the core, and wherein the particulate oxide or (oxy)hydroxide has a span of the particle size of the secondary particles in the range of 0.15 to 0.7 as determined by laser diffraction, and wherein the span refers to (D90-D10) / D50. Such particulate (oxy)hydroxide or oxide of TM is also referred to as a precursor of the present invention. Preferably, at least 60 mol-%, more preferably 82 to 97 mol-% of TM is nickel. In other embodiments, at least 60 mol-%, for example 60 to 75 mol-% of TM is manganese.

[0072] A gradient of 1.0 refers to a uniform distribution of sulfate over the particle radius.

[0073] Preferably, the outer sphere has a thickness in the range of 0.5 to 2 pm, but can account for at most 50% of the radius of the particles according to the present invention.

[0074] The term (oxy)hydroxide includes not only compounds with a molar oxide:hydroxide ratio of 1 :1, but also any TM compound with a molar oxide:hydroxide ratio in the range of 10:1 to 1 :10.

[0075] After carrying out step (c), the washed filter cake is dried, preferably at a temperature in the range of 80°C to 120°C, for example in air or in vacuum, in order to collect the particulate (oxy)hydroxide of TM according to the present invention. The drying can be carried out in a time period of 30 minutes to 24 hours.

[0076] In optional step (h), the (oxy)hydroxide of TM provided after drying of the filter cake of step (c) is calcined at a temperature in the range of 400°C to 600°C, thereby obtaining an oxide of TM having a residual moisture content of 200 to 500 ppm. Especially when the TM contains significant amounts of manganese, partial oxidation of the TM and in particular of the manganese occurs, and the oxide is not strictly stoichiometric TMO.

[0077] The residual moisture content can be determined, for example, by Karl-Fischer titration.

[0078] Step (h) can have a duration in the range of 0.5 to 7 hours, preferably 1 to 2 hours.

[0079] In one embodiment of the present application, step (h) is carried out in a roller hearth kiln, a pusher kiln or, preferably, in a plowshare mixer with a heating system, and even more preferably in a rotary kiln, for example in a rotary kiln with an inclination of 0.5° to 3°. In a rotary kiln, 0.5 to 2 revolutions per minute are preferred. On a laboratory scale, step (h) can also be carried out in a muffle furnace.

[0080] In one embodiment of the present application, step (h) is carried out under an atmosphere of air, synthetic air or nitrogen.

[0081] In an alternative embodiment, the washed filter cake of step (c) can be transferred directly to a furnace, for example a rotary kiln, and dried and dewatered in a single furnace. Such a furnace then preferably has at least two temperature zones, for example three or four, with the highest temperature being in the range of 400°C to 600°C.

[0082] A further aspect of the present application relates to precursors, i.e. oxides or (oxy)hydroxides of TM. They are most preferably made according to the inventive process.

[0083] In one embodiment of the present application, the precursors of the present application comprise secondary particles, which are agglomerates of primary particles. The average diameter (D50) of the precursors of the present application is preferably in the range of 2 to 20 pm, more preferably 3 to 17 pm and even more preferably 3 to 5 or 7 to 15 pm. The average particle size can be determined, for example, by light scattering or laser diffraction or electroacoustic spectroscopy. The above particle size refers to the secondary particle diameter. While (D50) is more accurately referred to as median or percentile 50, it will also be referred to as average diameter in the present application.

[0084] The span of the particle size distribution of the precursors of the present application (hereinafter also referred to as “span”) is in the range of 0.15 to 0.70, preferably 0.18 to 0.55 and more preferably 0.20 to 0.35. The span is defined as [(D90) - (D10)] / (D50), wherein the values of (D90), (D50) and (D10) are determined by dynamic light scattering and refer to the respective percentile values. In an alternative embodiment, the span of the particle size distribution of the precursors of the present application is in the range of 0.71 to 2.0, preferably 0.80 to 1.50.

[0085] The secondary particles of the precursor of the present application can have an irregular shape, but in a preferred embodiment the particulate material has a regular shape, for example spheroid or even spherical. The aspect ratio can be in the range of 1 and 10, preferably 1 to 3 and even more preferably 1 to 1.5. The aspect ratio is defined as the ratio of the width to the length, or in particular the ratio of the particle size in the longest dimension to the particle size in the shortest dimension. A perfect spherical particle has an aspect ratio of 1.

[0086] The primary particles of the precursor of the present application can have a needle or flake type shape. The diameter of the primary particles of the precursor of the present application refers to the diameter of the secondary particles.

[0087] In one embodiment of the present application, the oxide of the TM from step (h) has a specific surface area (BET) in the range of 50 to 120 m2 / g, as determined by nitrogen adsorption after drying for 60 min at 120 °C according to DIN-ISO 9277:2003-05. 2

[0088] In an alternative embodiment, the washed filter cake of step (c) can be directly transferred into a furnace, for example a rotary kiln, and dried and dewatered in a single furnace. Such a furnace then preferably has at least two temperature zones, for example three or four, with the highest temperature in the range of 400 °C to 600 °C.

[0089] In one embodiment of the present application, the particulate oxide of the present application has a moisture content in the range of 10 to 2,000 ppm, as determined by Karl-Fischer titration. ppm are weight ppm or ppm by weight.

[0090] The TM in the precursor of the present application is a combination of metals according to general formula (I)

[0091] (Ni a Co b Mn c ) 1-d M d (I)

[0092] wherein

[0093] a is in the range of 0.25 to 0.98,

[0094] b is 0 or in the range of 0.02 to 0.2,

[0095] c is in the range of 0 to 0.75, and

[0096] d is in the range of 0 to 0.1, for example 0 or 0.01 to 0.05,

[0097] M is selected from the group consisting of Mg, Al, Ti, Zr, Mo, W, Nb, Sb and Ta,​

[0098] a + b + c = 1 and b + c > 0.

[0099] In a preferred embodiment of the present application, the variables in TM are defined as follows

[0100] a is in the range of 0.6 to 0.98,

[0101] b is in the range of 0.02 to 0.2,

[0102] c is in the range of 0 to 0.2, and

[0103] d is in the range of 0 to 0.1, e.g. 0 or 0.01 to 0.05.

[0104] In another preferred embodiment of the present application, TM corresponds to the general formula (la)

[0105] (Ni a Co b Mn c ) 1-d M d (Ia)

[0106] wherein

[0107] a is in the range of 0.25 to 0.4,

[0108] b is in the range of 0 to 0.2,

[0109] c is in the range of 0.6 to 0.75, and

[0110] d is in the range of 0 to 0.1, e.g. 0 or 0.01 to 0.05,

[0111] M is selected from the group consisting of Mg, Al, Ti, Zr, Mo, W, Nb, Sb and Ta,

[0112] a + b + c = 1.

[0113] In one embodiment of the present application, at least 60 vol-% of the secondary particles of the (oxy)hydroxide or oxide of the present application are agglomerated from primary particles which are substantially radially oriented.

[0114] “Substantially radially oriented” does not require perfect radial orientation, but includes deviations from perfect radial orientation of at most 11 degrees, preferably at most 5 degrees, in SEM analysis.

[0115] Preferably, at least 60 vol-% of the secondary particles are filled with primary particles which are radially oriented. Preferably, only a minor inner portion of the volume of those particles, e.g. at most 40%, preferably at most 20%, is filled with primary particles which are not radially oriented, e.g. primary particles which are randomly oriented.

[0116] In one embodiment of the present application, the particulate transition metal (oxy)hydroxide or oxide of the present application has a shape factor in the range of 0.85 to 1 and an axis ratio of the bounding box in the range of 1.00 to 1.20.

[0117] To determine the axis ratio of the bounding box of an individual particle, the smallest possible rectangular bounding box is set around the top view SEM image of the particle. The axis ratio is calculated from the length of the two sides al and a2 (with al > a2) by: Axis ratio of the bounding box = al / a2.

[0118] While a perfect sphere would have an axis ratio of the bounding box of 1.0, all deviations from perfect sphericity will result in an axis ratio > 1.0.

[0119] In one embodiment of the present application, the specific surface area (BET) of the precursor of the present application is in the range of 2 to 120 m2 / g, for example determined by nitrogen adsorption according to DIN-ISO 9277:2003-05. The degassing temperature is 120 °C. 2

[0120] The particulate (oxy)hydroxide and oxide of the present application are very suitable for the manufacture of cathode active materials for lithium ion batteries. A further aspect of the present application therefore relates to the use of the particulate (oxy)hydroxide and oxide of the present application for the manufacture of cathode active materials for lithium ion batteries.

[0121] A further aspect of the present application relates to a process for the manufacture of cathode active materials for lithium ion batteries, wherein the process comprises the step of converting the particulate (oxy)hydroxide or oxide of the present application with a lithium compound and optionally with a dopant selected from the group consisting of oxides, (oxy)hydroxides and hydroxides of metals selected from the group consisting of Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta at a temperature in the range of 600 °C to 1,100 °C. Such lithium compounds are preferably selected from the group consisting of lithium oxide, lithium carbonate and especially lithium hydroxide. Peroxides like Li202are also possible, alone or together with any of the foregoing. In embodiments where the nickel content of the TM is 60 mol-% or more, the molar ratio of lithium to TM is preferably in the range of 1.00 to 1.05 and in embodiments where the manganese content of the TM is 60 mol-% or more, the molar ratio of lithium to TM is preferably in the range of 1.10 to 1.50.

[0122] The present application is further illustrated by working examples.

[0123] Working Examples

[0124] The data given in ppm refer to ppm by weight.

[0125] ​The following apparatus was used: 800-1 stirred tank reactor (A.1) equipped with four baffles and a two-stage 45° pitched blade turbine agitator connected to a layer clarifier. A suspension buffer was connected to a filter press equipped with containers to collect the wash filtrates (B.1) and (C.1) and a reverse osmosis unit (D.1).

[0126] I. Manufacture of the inventive and comparative hydroxide and oxide precursors

[0127] The following feeds were provided:

[0128] Solution (a.1): NiSO4, CoSO4 and MnSO4 dissolved in deionized water (molar ratio 91 :4.5:4.5, total transition metal concentration: 1.45 mol / kg)

[0129] Solution (b.1): 25 wt% NaOH dissolved in deionized water

[0130] Solution (g.1): 25 wt% ammonia in deionized water

[0131] Solution (e1.1): water from reverse osmosis step (d) fed to step (c)

[0132] Solution (e2.1): water from reverse osmosis step (d) fed to step (a)

[0133] Seed suspension (d.1): average particle size 4.0 pm, span = 0.74, solid content 240 g / l, mother liquor of the seed suspension was an aqueous Na2SO4 solution (about 15 w%)

[0134] Unless explicitly stated otherwise, percentages refer to % by weight. All pH values were determined at 23 °C.

[0135] I.1 Manufacture of comparative hydroxide C-P-CAM.1

[0136] Step C-(a.1):

[0137] An 800 I stirred tank reactor with a baffle and a two-stage pitched blade turbine (45° angle, diameter 0.4 m) was charged with 700 I of fresh deionized water. The stirrer speed was adjusted to 150 rpm while the water was heated to 55 °C via the reactor double jacket. The temperature was kept constant at 55 °C throughout the experiment. Then, solution (y.1) was added to adjust the ammonia concentration to 0.5 w%. As next step, 35 kg of suspension (d.1) were added. The pH value was 11.54. Subsequently, the stirrer speed was adjusted to 396 rpm and the simultaneous feeding of solutions (a.1), (b.1) and (y.1) was started. During the synthesis, the stirrer speed was stepwise decreased to a final stirrer speed of 130 rpm. The pH value at 23 °C was kept constant at 11.5 by adjusting the flow of (b.1) and the NH3 concentration was kept constant at 0.5 w% by adjusting the flow of (y.1). The ratio between the reactor volume (800 I) and the volumetric flow of the feeds (a.1), (b.1) and (y.1) (called equivalent to residence time) was increased with the run time resulting in an average residence time equivalent to 5.7 h. The mother liquor was continuously withdrawn from the suspension using a lamellar clarifier resulting in a final solids content of 364 g / L in the reactor after 23.5 h run time. The withdrawn mother liquor was collected in a stirred collection vessel. The further treatment of the mother liquor is shown in step (d.1). After completion of the batch treatment, all feed streams were stopped and the final suspension from the reactor and the lamellar clarifier was discharged into a stirred suspension buffer vessel.

[0138] Step C-(b.1): The suspension was filtered using a filter press. The filtrate was discarded.

[0139] Step C-(c.1): The filter cake was subsequently washed in the filter press first using solution (b.1) and then using DI water. The sodium hydroxide wash filtrate was discarded. The water wash filtrate was collected in a collection vessel from which a continuous stream was fed to a reverse osmosis unit (step d.1). Furthermore, a part of the mother liquor was collected in a collection vessel during step C-(a.1) and was fed to the reverse osmosis unit.

[0140] The washed filter cake was dried in a box dryer at 120 °C for 15 h to obtain C-P-CAM.1 with a molar composition of Ni:Co:Mn = 91 :4.5:4.5, an average particle size (d50) = 14.1 pm and a span = 0.27. Cross-sectional TEM EDX analysis was performed which revealed a 2.2 times higher concentration of sulphate in the outer surface of the particles than in the core.

[0141] Step (d.1):

[0142] Reverse osmosis is performed with 100 bar to remove water from the combination of the wash filtrate from step (c.1) and the mother liquor from step (a.1) to obtain a permeate and a retentate (also called concentrated filtrate). The permeate (water) is collected in a non-stirred collection tank.

[0143] I.2 Manufacture of hydroxide precursor P-CAM.2 of the invention

[0144] Step (a.2)

[0145] The hydroxide precursor P-CAM.2 of the invention is produced like C-P-CAM.1 but with the following modifications. As step (e3.1) water from (d.1) is used to charge the reactor before the start of the co-precipitation. During the precipitation phase, the feed solution (e2.1) is combined with solution (β.1) before being fed to the reactor. Specifically, the addition of solution (e2.1) starts after 5 h of run time. The mother liquor taken out during this step is again collected in a collection vessel and again treated in reverse osmosis (step d.2).

[0146] Step (b.2): The suspension from step (a.2) is filtered using a filter press. The filtrate is discarded.

[0147] Step (c.2): The filter cake from step (b.2.) is washed in the filter press first using solution (β.1) and then with fresh water combined with the water produced in step (d.1) in a ratio of 1 :10 by weight. Thereby, the amount of washing fresh water required can be significantly reduced compared to step (c.1). The wash filtrate from step (c.2) is again collected in a collection vessel from which a continuous flow is fed to the same reverse osmosis unit as (d.1) (step d.2).

[0148] The washed filter cake is dried in a box dryer at 120 °C for 15 h to obtain P-CAM.2 with a molar composition Ni:Co:Mn = 91 :4.5:4.5, an average particle size (d50) = 14.0 pm and a span = 0.27. Cross-sectional TEM EDX analysis was performed which revealed a 1.3 times higher concentration of sulphate in the outer surface of the particles than in the core.

[0149] I.3 Manufacture of comparative oxide precursor oxygen-C-P-CAM.1

[0150] Comparative C-P-CAM.1 was heated under flowing air in a Linn oven at 450°C for 2 hours to obtain mixed metal oxide oxygen-C-P-CAM.1. Comparative oxygen-C-P-CAM.1 has an average particle size (D50) of 14.1 pm, a span of 0.27. Cross-section TEM EDX analysis was performed which revealed a 2.2 times higher concentration of sulphate in the outer surface of the particles than in the core.

[0151] I.4 Manufacture of the oxide precursor oxygen-P-CAM.2 of the invention

[0152] P-CAM.2 of the invention was heated under flowing air in a Linn oven at 450°C for 2 hours to obtain mixed metal oxide oxygen-P-CAM.2. Oxygen-P-CAM.2 of the invention has an average particle size (D50) of 14.0 pm, a span of 0.27. Cross-section TEM EDX analysis was performed which revealed a 1.3 times higher concentration of sulphate in the outer surface of the particles than in the core.

[0153] II Manufacture of the cathode active material

[0154] II.1 Manufacture of comparative C-CAM.1 using oxygen-C-P-CAM.1

[0155] 30 g of comparative oxygen-C-P-CAM.1 was mixed with LiOH monohydrate (molar ratio Li / metal = 1.04), 133 mg of Ti02 and 122 mg of Zr02 in a mill for 15 minutes. The resulting mixture was loaded into a crucible and transferred into a Linn oven. The temperature was increased to 750°C under flowing oxygen gas at a rate of 2 C / min and then held constant at 750°C for 8 hours and subsequently allowed to cool naturally under flowing oxygen gas. The resulting powder was then de-agglomerated in a mill and sieved.

[0156] 30 g of powder was then added to 15 ml of deionized water, stirred for 2 minutes and then immediately filtered on a Buchner funnel to remove the water. The wet cake was then dried at 120°C under N2atmosphere at reduced pressure for 10 hours.

[0157] The resulting powder was then dry coated with boric acid by mixing 30 g of powder, mixing media and 30 mg of boric acid on a roller mill at low speed for 40 minutes. The dried powder was loaded into a crucible and subjected to a heat treatment in a Linn oven. The Linn oven was heated to 300°C under an oxygen atmosphere for 2 hours and allowed to cool naturally. Comparative CAM.1 was obtained with a (D50) of 13.9 pm, a span of 0.26.

[0158] II.2 Manufacture of CAM.2 using oxygen-P-CAM.2 of the invention

[0159] CAM.2 was prepared from oxygen-C-CAM.2 in a similar manner to C-CAM.1. CAM.2 with a (D50) of 14.0 μm and a span of 0.26 was obtained.

[0160] III. Testing of Cathode Active Materials

[0161] Electrochemical tests were performed on CAM.2 of the present invention and the comparative C-CAM.1 to study the effect of surface coating on electrochemical performance.

[0162] III.1 Cathode Manufacturing

[0163] Positive electrode: PVDF adhesive (polyvinylidene fluoride, ...) 5130) was dissolved in NMP (Merck) to produce a 7.5 wt.% solution. For electrode preparation, a binder solution (3 wt.%), graphite (SFG6L, 2 wt.%), and carbon black (Super C65, 1 wt.%) were suspended in NMP. After mixing using a planetary centrifugal mixer (ARE-250, Thinky Corp., Japan), CAM.2 or C-CAM.1 of the present invention (94 wt.%) was added, and the suspension was stirred again to obtain a lump-free slurry. The solids content of the slurry was adjusted to 65%. The slurry was coated onto Al foil using a KTF-S roll-to-roll coater (Mathis AG). All electrodes were calendered before use. The cathode material thickness was 70 μm, corresponding to 15 mg / cm². 2 Before battery assembly, all electrodes were dried at 105°C for 7 hours.

[0164] III.2 Electrolyte Manufacturing

[0165] A base electrolyte composition containing 12.7 wt% LiPF6, 26.2 wt% ethylene carbonate (EC), and 61.1 wt% ethyl methyl carbonate (EMC) (EL matrix 1) (based on the total weight of EL matrix 1) was prepared. 2 wt.% ethylene carbonate (VC) (EL matrix 2) was added to this base electrolyte formulation.

[0166] III.3 Testing Battery Cell Manufacturing - Button-type Half-cell Cell

[0167] A coin-type half-cell unit (diameter of 20 mm and thickness of 3.2 mm) comprising a cathode as prepared under II.1.1 and lithium metal as working and counter electrode, respectively, was assembled and encapsulated in an Ar-filled glovebox. Furthermore, the cathode and anode and the separator were stacked in the order cathode / / separator / / Li foil to produce a half-coin cell. Thereafter, 0.15 mL of EL matrix 1 described above under III.2 was introduced into the coin cell.

[0168] III.4 Evaluation of the battery cell performance

[0169] The initial, C-rate and cycling performance was measured as follows: The coin half-cell units according to II.3 were tested at room temperature in a voltage range between 4.3 V and 2.8 V. For the initial cycle, the initial lithiation was performed in CC-CV mode (i.e. a constant current (CC) of 0.1 C was applied) until 4.3 V was reached, followed by a CV step until the current dropped to 0.01 C. After a 10 min resting time, the delithiation was performed under constant current of 0.1 C up to 2.8 V. For the C-rate tests, the charge and discharge rates were adjusted accordingly. For the cycling test, the constant current was chosen to be 1 C until 100 cycles were reached. The results are summarized in Table 1.

[0170] Table 1 : Physical and electrochemical data of the cathode active materials.

[0171]

Claims

1. A process for the preparation of particulate (oxy)hydroxides of TM, wherein TM is a combination of nickel and at least one metal selected from the group consisting of Co and Mn, and wherein TM is defined according to general formula (I): TM(OH)a(SO4)b(Mc)d (I) wherein a is in the range of 0.25 to 0.98, b is 0 or in the range of 0.02 to 0.2, c is in the range of 0 to 0.75, and d is in the range of 0 to 0.1, and a+b+c = 1, and b+c > 0, M is selected from the group consisting of Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta, and combinations of at least two of the foregoing, wherein the process comprises the following steps: (a) precipitating a hydroxide of TM by combining in a stirred tank reactor one or more aqueous solutions (a) containing sulphates of Ni and at least one transition metal selected from the group consisting of Co and Mn, and optionally at least one further metal selected from the group consisting of Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta, and an aqueous solution (b) containing sodium hydroxide, and optionally an aqueous solution (g) containing a complexing agent, (b) separating the precipitated TM hydroxide from the continuous phase by a filtration step, thereby obtaining a filter cake and a filtrate, (c) subsequently washing the resulting filter cake with an aqueous medium, thereby obtaining a washed filter cake and a washing filtrate containing sodium sulphate, (d) removing water from the washing filtrate, thereby obtaining a concentrated filtrate and water, (e) at least partially recycling the water from step (d) and using it as at least a part of (el) the aqueous medium used for washing in filtration step (c), or (e2) the reaction medium in step (a), or (e3) process water. In step (a) the mother liquor is withdrawn during step (a) by a solid-liquid separation device and combined with the washing filtrate from step (c). (Ni a Co b Mn c ) 1-d M d (I) The mother liquor withdrawn during step (a) by a solid-liquid separation device is mixed with the filtrate from step (b) and optionally with the concentrated filtrate from step (d), and wherein the resulting mixture is separated into a concentrated stream and water in another device similar to step (d), and wherein at least a part of the water obtained is used similar to step (e). The solid-liquid separation device is selected from the group consisting of a clarifier, a thickener and a candle filter. The recycled water from step (d) is diluted with fresh water in a ratio of 1 : 10 to 10: 1 for use as washing water in step (c) or reaction medium in step (a). At least a part of the filtrate from step (b) is combined with the washing filtrate from step (c). The sulphate content of the washing water before starting step (b) or the sulphate content of the reaction medium at the start of step (a) is up to 2% by weight. Step (d) is selected from the group consisting of reverse osmosis processes. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 2. The method of claim 1, wherein, ​ 3. The method of claim 2, wherein, ​ 4. The method of claim 2, wherein, ​ 5. The method according to any one of the preceding claims, wherein, ​ 6. The method according to any one of the preceding claims, wherein, ​ 7. The method according to any one of the preceding claims, wherein, ​ 8. The method of any of the preceding claims, wherein, ​ 9. A particulate (oxy)hydroxide or oxide of TM, wherein TM is a combination of nickel with at least one metal selected from cobalt and manganese, and optionally at least one further metal selected from Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta, wherein the particulate (oxy)hydroxide or oxide has a median particle size (D50) in the range of 2 to 20 pm, and wherein the particulate (oxy)hydroxide or oxide has a sulphate concentration in the outer surface of the particles which is at most 2.0 times higher than in the core, and wherein the particulate oxide or (oxy)hydroxide has a span of the particle size of the secondary particles in the range of 0.15 to 0.7 as determined by laser diffraction, and wherein the span refers to (D90-D10) / D50, and wherein TM is a combination of metals according to general formula (I) (Ni a Co b Mn c ) 1-d M d (I) wherein a is in the range of 0.25 to 0.98, b is 0 or in the range of 0.02 to 0.2, c is in the range of 0 to 0.75, and d is in the range of 0 to 0.1, M is selected from Mg, Al, Ti, Zr, Mo, W, Sb, Nb and Ta, a + b + c = 1, and b + c > 0.

10. The particulate oxide according to any one of claims 9 or 10, wherein, The sulphate concentration gradient is essentially constant over the diameter of the particles.

11. The particulate (oxy)hydroxide or oxide according to claim 9 or 10, wherein The span of the particle size of the primary particles is in the range of 0.15 to 2 as determined by laser diffraction, and wherein the span refers to (D90-D10) / D50.

12. Use of the particulate (oxy)hydroxide or oxide according to any one of claims 9 to 11 for the manufacture of a cathode active material for a lithium ion battery.

13. A method for manufacturing a cathode active material for a lithium ion battery, wherein the method comprises the steps of: The particulate (oxy)hydroxide or oxide according to any one of claims 9 to 11 is converted with a lithium compound and optionally with a dopant selected from oxides, (oxy)hydroxides and hydroxides of metals selected from Ti, Zr, Mo, W, Al, Sb, Mg, Nb and Ta at a temperature in the range of 600 °C to 1,100 °C.

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