Method for making a composite hydroxide, composite hydroxide, and use of composite hydroxide

Abstract

Process for making a composite hydroxide of TM with an average particle diameter (d50) in the range of from 3 to 25 µm wherein TM corresponds to combinations of metals according to general formula (I) NiaCobMnc)1-dM1 d wherein a is in the range of from 0.60 to 0.95, b is in the range of from 0.025 to 0.2, c is in the range of from 0.03 to 0.2, and d is in the range of from zero to 0.05, M1 is selected from Al, Ti, Zr, W, Mo, Mg, Nb, Ta, Ca, and combinations of at least two of the foregoing, a + b + c = 1, wherein the manganese has an average oxidation state in the range of from 2.1 to 2.8, wherein said process comprises the steps of: (a) co-precipitation of a hydroxide of TM from an aqueous medium in one or more sub-steps, (b) recovering the precipitated hydroxide of TM as a concentrated slurry, (c) removing the water at a temperature above 100°C in a way that the exposure to air is 15 seconds or less at a temperature above 100 °C.

Description

[0001] Method for making a composite hydroxide, composite hydroxide, and use of composite hydroxide

[0002] The present invention is directed to a process for making a composite hydroxide of TM with an average particle diameter (d50) in the range of from 3 to 25 pm wherein TM

[0003] (NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.60 to 0.95, b is in the range of from 0.025 to 0.2, c is in the range of from 0.03 to 0.2, and d is in the range of from zero to 0.05,

[0004] M1is selected from Al, Ti, Zr, W, Mo, Mg, Nb, Ta, Ca, and combinations of at least two of the foregoing, a + b + c = 1 , wherein the manganese has an average oxidation state in the range of from 2.1 to 2.8, wherein said process comprises the steps of:

[0005] (a) co-precipitation of a hydroxide of TM from an aqueous medium in one or more sub-steps,

[0006] (b) recovering the precipitated hydroxide of TM as a concentrated slurry,

[0007] (c) removing the water at a temperature above 100°C in a way that the exposure to air is 15 seconds or less at a temperature above 100 °C.

[0008] Lithiated transition metal oxides are currently used as electrode active materials for lithium-ion batteries. Extensive research and developmental work have been performed in the past years to improve properties like charge density, specific energy, but also other properties like the reduced cycle life and capacity loss that may adversely affect the lifetime or applicability of a lithium-ion battery. Additional effort has been made to improve manufacturing methods.

[0009] In a typical process for making cathode materials for lithium-ion batteries, first a so-called precursor is being formed by co-precipitating the transition metals as carbonates, oxides or preferably as hydroxides that may or may not be basic, for example oxyhydroxides. The precursor is then mixed with a source of lithium such as, but not limited to LiOH, U2O or U2CO3 and calcined (fired) at high temperatures. Lithium source(s) can be employed as hydrate(s) or in dehydrated form. The calcination - or firing - often also referred to as thermal treatment or heat treatment of the precursor - is usually carried out at temperatures in the range of from 600 to 1000 °C. During the thermal treatment a solid-state reaction takes place, and the electrode active material is formed. The thermal treatment is performed in the heating zone of an oven or kiln.

[0010] Numerous properties of lithium-ion batteries still leave room for improvement. Capacity fading upon repeated cycling and resistance build-up are topics. Numerous reasons have been discussed in the past. One of the reasons discussed is the crack formation in particles of the cathode active material during lithiation and de-lithiation. Cathode active material particles expand and contract during each cycle which may lead to crack formation. Cracks already existing in cathode active material particles can severely limit the mechanical integrity of the secondary particle structure resulting in the electrical contact loss of primary particles, which are then electrically isolated and cannot contribute to the capacity of the battery.

[0011] In addition, cracking of cathode active material particles during the manufacturing, especially in the course of the calcination may result into the fragmentation of the particles. This leads to transportation of fragments into the off-gas during calcination and to in increased necessity to clean the off-gas. In cases where high amounts of fragments are removed with filters, a high exchange rate of filters may be required that can result in maintenance breaks.

[0012] An important class of cathode active materials for lithium-ion batteries contains nickel and manganese, for example at least 60 mol-% nickel and at least 3 mol-% manganese, percentages referring to metals other than lithium. The most widely-spread class is the so-called NCM (or NMC) material, NCM standing for nickel-cobalt-manganese materials.

[0013] It was an objective of the present invention to provide cathode active materials that contain nickel and manganese, especially at least 60 mol-% nickel and at least 3 mol-% manganese, with a reduced tendency of cracking upon repeated cycling, and it was an objective to provide a process for making such cathode active materials.

[0014] To a certain extent, properties of the precursor translate into properties of the respective electrode active material, such as particle size distribution, content of the respective transition metals and more. In other aspects, properties of the precursor indirectly influence the properties of the resulting cathode active material. It is therefore possible to influence the properties of electrode active materials by steering the properties of the precursor. Accordingly, in a case a precursor comprises a lot of cracked particles is lithiated this will translate into a cathode active material that also exhibits a lot of cracked particles. Cracked particles can negatively affect the processability of the cathode active material for the electrode preparation the electrochemical performance. Accordingly, the process as defined at the outset has been found, hereinafter also defined as “inventive process” or “process according to the (present) invention”. The inventive process comprises at least three steps, hereinafter also referred to as step (a) and step (b) and step (c), or - even more briefly - (a), and (b), respectively. The inventive process may include further - optional - steps. Steps (a) and (b) are described in more detail below. By the inventive process, a highly spherical precursor with narrow particle size distribution is obtained.

[0015] It has been found that by the way of a fast water removal from the freshly precipitated precursor, the mechanical stability of the precursor and of the derived cathode active materials may be influenced. In particular, it as been found that a reduced oxidation of manganese in the precursor leads to improved properties of resultant cathode active materials.

[0016] One aspect of the present invention is thus a process for making a composite hydroxide of TM with an average particle diameter (d50) in the range of from 3 to 25 pm wherein TM is a combination of metals according to formula (I), see below, wherein the manganese has an average oxidation state in the range of from 2.1 to 2.8, preferably 2.2 to 2.7, more preferably 2.25 to 2.65, said process comprises the steps of:

[0017] (a) co-precipitation of a hydroxide of TM from an aqueous medium in one or more sub-steps,

[0018] (b) recovering the precipitated hydroxide of TM as a concentrated slurry,

[0019] (c) removing the water in a way that the exposure to air is 15 seconds or less at a temperature above 100 °C.

[0020] Steps (a) to (c) will be described in more detail below.

[0021] The inventive process is a process for making a composite hydroxide of TM. Said hydroxide then serves as a precursor for cathode active materials, and it may therefore also be referred to as precursor.

[0022] In one embodiment of the present invention, the resultant precursor is comprised of secondary particles that are agglomerates of primary particles.

[0023] In one embodiment of the present invention the specific surface (BET) of the resultant precursor is in the range of from 1 to 70 m2 / g, determined by nitrogen adsorption, for example in accordance with to DIN-ISO 9277:2003-05. The outgassing temperature is 120°C.

[0024] The precursor is a hydroxide of TM wherein TM comprises at least 60 mol-% Ni and at least 3 mol-% Mn, both referring to TM, and cobalt, and, optionally, at least one further element selected from Co, Ti, Zr, Ca, Si, Mo, W, Al, Mg, Nb, Ca, and Ta, preferably a combination of Al, W, Mg and Nb or a combination of Ti, Zr, Al and Mg. In one embodiment of the present invention, TM is a combination of metals according to general formula (I)

[0025] (NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.60 to 0.95, preferably from 0.80 to 0.94, b is in the range of from 0.025 to 0.2, preferably from 0.025 to 0.15, c is in the range of from 0.03 to 0.2, preferably from 0.04 to 0.15, and d is in the range of from zero to 0.1 , preferably 0.02 to 0.05,

[0026] M1is selected from Mg, Al, Ti, Zr, Mo, W, Al, Mg, Nb, and Ta, preferably selected from Al, Mg, Nb, W, Ti, and Zr, more preferably a combination of Mg and Al or a combination of Al, Mg, W and Nb or a combination of Mg and Al or a combination of Al, Mg, Ti and Zr, and a + b + c = 1.

[0027] In each case, TM may contain traces of further metal ions other than the above, for example traces of ubiquitous metals such as sodium, calcium, iron, or zinc, as impurities but such traces will not be taken into account in the description of the present invention. Traces in this context will mean amounts of 0.05 mol-% or less, referring to the total metal content of TM.

[0028] It is preferred that the amount of lithium in precursor below detection level.

[0029] Precursors as used herein are particulate materials. In one embodiment of the present invention, precursors have an average particle diameter D50 in the range of from 3 to 20 pm, preferably from 4 to 16 pm. The average particle diameter may be determined, e. g., by light scattering or LASER diffraction or electroacoustic spectroscopy. The particles are composed of primary particles, in particular they are agglomerates of primary particles, and the above particle diameter refers to the secondary particle diameter. Although (D50) is - strictly speaking - the median value rather than an average diameter both expressions are used interchangeably.

[0030] In one embodiment of the present invention, the span of the particle diameter distribution of precursors is in the range of from 0.2 to 2.0, preferably from 0.25 to 0.35 or from 0.6 to 1.5. The span is defined as [(D90) - (D10)] / (D50), with the values of (D90), (D50) and (D10) being the respective percentiles determined by dynamic light scattering or by X-ray diffraction. Said particles of precursors may have an irregular shape but in a preferred embodiment, said particulate material has a regular shape, for example spheroidal or even spherical. The aspect ratio may be in the range of from 1 and 10, preferably from 1 to 3 and even more preferably from 1 to 1.5. The aspect ratio is defined as the ratio of width to length or specifically the particle diameter in the longest dimension versus the particle diameter in the shortest dimension. Perfectly spherical particles have an aspect ratio of 1 .

[0031] Step (a) includes co-precipitation of a hydroxide of TM from an aqueous medium in one or more sub-steps.

[0032] Said co-precipitation by be performed by combining an aqueous solution (a) containing water- soluble salts of Ni and lithium and of at least one transition metal selected from Co and Mn, and of a water-soluble compound of at least one further element selected from Ti, Zr, Mo, W, Al, Mg, Ca, Nb, and Ta, and an aqueous solution (P) containing sodium or potassium hydroxide and, optionally, an aqueous solution (y) containing a complexing agent, for example ammonia.

[0033] The term water-soluble salts of nickel and manganese or of cobalt or metals other than nickel and cobalt and manganese refers to salts that exhibit a solubility in distilled water at 25°C of 25 g / l or more, the amount of salt being determined under omission of crystal water and of water stemming from aquo complexes. Water-soluble salts of nickel and cobalt and manganese may preferably be the respective water-soluble salts of Ni2+and Co2+and Mn2+. Examples of water- soluble salts of nickel and cobalt and manganese are the sulfates, the nitrates, the acetates and the halides, especially chlorides. Preferred are nitrates and sulfates, of which the sulfates of nickel and cobalt and manganese are more preferred.

[0034] The co-precipitation is preferably performed under an atmosphere of nitrogen or a noble gas, for example argon. Said atmosphere of nitrogen or a noble gas may be created by bubbling nitrogen or the respective noble gas through the aqueous medium in which step (a) is performed, or by performing step (a) under a blanket of nitrogen or the respective noble gas. The exclusion of oxygen may be improved by flushing the vessel in which step (a) is performed with nitrogen or the respective noble gas prior to the start of the co-precipitation.

[0035] In one embodiment of the present invention, step (a) is performed in the continuous mode. In an alternative embodiment, step (a) is performed discontinuously.

[0036] In one embodiment of the present invention, step (a) is performed in a cascade of at least two stirred tank reactors, and the reaction conditions in the two stirred tank reactors are not identi- cal, for example by different pH values or a different stirrer energy input. In one embodiment of the present invention, step (a) is performed in a cascade of at least two stirred tank reactors, and the pH value in the first stirred tank reactor is higher than in the second, for example 12.5 to 13.5 in the first stirred tank reactor and 10.0 bis 12.0 in the second stirred tank reactor.

[0037] In one embodiment of the present invention, mother liquor is withdrawn during the coprecipitation, for example by way of candle filters or by way of at least one clarifier, for example by way of a lamellar clarifier. The term mother liquor refers to water that contains dissolved salt formed in the co-precipitation reaction such as alkali metal sulfate, and complexing agent - if applicable - such as ammonia. The removal of mother liquor leads to a higher solids content. Mother liquor may further contain traces of nickel complex salt such as amine complexes.

[0038] In step (b), precipitated hydroxide of TM is recovered as a concentrated slurry, for example with a solids content in the range of from 200 to 1 ,000 g / l. The solids content may be determined by density measurements or ICP (inductively coupled plasma) or by Coriolis meters and refers to the slurried particles. Dissolved compounds such as, but not limited to Na2SC>4 are neglected in this context.

[0039] Step (b) may be performed by a solid-liquid separation step, for example a filtration, sedimentation, or centrifugation, followed by washing the solid part with an aqueous medium such as water or aqueous alkali metal hydroxide solution, e.g., aqueous potassium hydroxide solution or aqueous sodium hydroxide solution. Preferred is filtration, e.g., with a band filter or a filter press or a vertical pressure filter.

[0040] Step (b) may be performed under an inert atmosphere, e.g., nitrogen or a noble gas. In other embodiments, step (b) is performed under air or decarbonized air.

[0041] Step (b) is preferably performed without external heating. In embodiments where the manufacture of co-precipitated hydroxide is performed at a temperature above ambient temperature, e.g., 45 to 70°C, natural cooling may be performed during step (b).

[0042] In one embodiment of the present invention, step (b) may be performed at a temperature in the range of from 5 to 35°C.

[0043] Preferably, step (b) includes one or more washing operations with, e.g., water or aqueous alkali hydroxide solution. A concentrated slurry or wet filter cake is obtained from step (b). In embodiments where step (b) is performed by filtration, a wet filter cake is obtained, containing for example 1 to 30% by weight of water.

[0044] In one embodiment of the present invention, solid residue from step (b) is re-slurried in water or in a vessel that may be shaped as loop, e.g., in a pulper. Preferably, then the solids content is in the range of from 20 to 80% by weight. A so-called concentrated slurry is obtained.

[0045] In step (c), water is removed from the concentrated slurry in a way that the exposure to air is 15 seconds or less at a temperature above 100 °C, preferably above 120°C. That means that water is removed at a temperature above 100°C by a fast process, and air is utilized as drying medium. Since the exposure to air is only short, no significant oxidation of manganese takes place during step (c). The term “exposure” further refers to the exposure of composite hydroxide of TM to air at the temperature of above 100°C.

[0046] A suitable maximum temperature is 400°C.

[0047] Neither vacuum drying nor drying under inert atmosphere is included in step (c) as main drying operation. In this context, the main drying operation is the drying operation that leads to the highest relative amount of water removal in the inventive process.

[0048] In one embodiment of the present invention, a flash-drying or spin flash-drying. In flash-drying, a wet filter cake or highly concentrated slurry is transferred into a drying chamber. In a spin flash dryer, a concentrated slurry or a wet filter cake is introduced into a dryer’s main chamber and dispersed by a rotating agitator. Hot air is introduced simultaneously.

[0049] In a preferred embodiment of the present invention, step (c) is a spray drying step.

[0050] Spray drying (or “spray-drying”) may be preferred in a spray dryer, for example a spray chamber or in a spray tower. Slurry obtained according to step (b) may be brought to a temperature preferably higher than ambient temperature, for example in the range of from 50 to 95°C, or - in the alternative - be used at ambient temperature. Slurry obtained in step (b) is then introduced into the spray dryer through one or more spray nozzles into a hot gas inlet stream, for example air, the slurry thereby being converted into droplets and the water being vaporized. The hot gas inlet stream may have a temperature in the range of from 185 to 550°C, preferably 260 to 400°C, and is usually air. In one embodiment of the present invention, the average residence time of hydroxide of TM in step (c) is in the range of from 1 second to 20 seconds, especially 2 to 15 seconds.

[0051] In one embodiment of the present invention, the pressure in the spray dryer in step (c) is normal pressure ± 100 mbar, preferably normal pressure ± 20 mbar, for example one mbar less than normal pressure.

[0052] In one embodiment of the present invention, step (c) is performed with air as drying gas or spraying gas. The spraying gas is the gas that is used in a nozzle for spray-drying.

[0053] In one embodiment of the present invention, step (c) is performed at a gas flow rate of 2000 to 8000 Nm3 / h, more preferably at a gas flow rate of 3000 to-6000 Nm3 / h. in this context, Nm3 / h refers to a volume at normal conditions, 20°C and 1 atm.

[0054] The drying efficiency depends on various parameter, e.g., solids content, temperature, and the like.

[0055] In one embodiment of the present invention, the dried hydroxide of TM is quenched immediately after step (c) in a containment where the hydroxide of TM is collected and cooled down by contact cooling with the walls of the containment in order to limit any oxidation of the hydroxide of TM. Such cooled walls may have a temperature in the range of from 5 to 30°C, preferably 10 to 25°C.

[0056] By performing step (c), a humid off-gas is formed that may contain some particulate hydroxide of TM, so-called dust. Form the off-gas, dust may be removed, for example by reverse air filters, baghouse filters, or electrostatic precipitators. Baghouse filters are preferred.

[0057] By performing the inventive process, particulate hydroxides of TM are obtained that are excellently suited as precursors for cathode active materials for lithium-ion batteries. Hydroxides of TM obtained from the inventive process may be converted with a source of lithium such as U2CO3 or LiOH or combinations of LiOH / Li2O2, with or without water of crystallization, in the absence or presence of one or more dopants such as, but not limited to oxides and hydroxides of Al, Mg, Ti, Zr, W, Mo, Y and Hf. Then, cathode active materials are obtained that have a very low tendency of crack formation upon cycling. Such cracks are within the secondary particle architecture. They typically form between grain boundaries of primary particles and are drawing through from the particle surface to the particle center. Another aspect of the present invention is directed towards composite hydroxides of TM, hereinafter also referred to as “inventive precursors”. Inventive precursors have an average particle diameter (d50) in the range of from 3 to 25 pm and are composite hydroxides of TM. TM is a combination of metals according to formula (I), and TM contains at least 60 mol-% nickel and at least 3 mol-% manganese, wherein the manganese in TM has an average oxidation state in the range of from 2.1 to 2.8, preferably 2.2 to 2.7, more preferably 2.25 to 2.65, and wherein the inventive precursor has a moisture content in the range from 0.1 to 1.0 wt% determined by Karl- Fischer titration.

[0058] The average oxidation state of manganese in TM may be determined by iodometric titration (thiosulfate). It is assumed that in hydroxide of TM, the average oxidation state of nickel and of cobalt is +2.0.

[0059] In one embodiment of the present invention TM corresponds to combinations of metals according to general formula (I)

[0060] (NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.60 to 0.95, preferably from 0.80 to 0.94, b is in the range of from 0.025 to 0.2, preferably from 0.025 to 0.15, c is in the range of from 0.03 to 0.2, preferably from 0.04 to 0.15, and d is in the range of from zero to 0.1 , preferably 0.02 to 0.05,

[0061] M1is selected from Al, Ti, Zr, W, Mo, Mg, Nb, Ta, Ca, and combinations of at least two of the foregoing, a + b + c = 1.

[0062] In one embodiment of the present invention, inventive precursors have a refraction maximum of above 5.0% from 500 to 700 nm, preferably from 550 to 650 nm, more preferably from 570 to 630 nm, measured by LIV-VIS spectrometry. The LIV-VIS spectra are preferably recorded in a quartz cuvette with powder inside the quartz cuvette. Preferably, said refraction maximum is 55% or lower. Preferably, inventive precursors have a green color. In one embodiment of the present invention, inventive precursors have a specific surface (“BET surface”) in the range of from 5 to 20 m2 / g, determined by nitrogen adsorption, for example in accordance with to DIN-ISO 9277:2003-05. The outgassing temperature is 120°C.

[0063] In one embodiment of the present invention, the span of the particle diameter distribution of inventive precursors is in the range of from 0.2 to 2.0, preferably from 0.25 to 0.35 or from above 0.35 to 0.69 or from 0.6 to 1.5. The span is defined as [(D90) - (D10)] / (D50), with the values of (D90), (D50) and (D10) being the respective percentiles determined by dynamic light scattering or by X-ray diffraction.

[0064] Inventive precursors are excellently suited for making cathode active materials for lithium-ion batteries.

[0065] A further aspect of the present invention is thus related to a process for making cathode materials from inventive precursors, said process also being referred to as inventive production process. The inventive production process comprises the steps of mixing an inventive precursor with a source of lithium and, optionally, with at least one oxide, hydroxide or oxyhydroxide of M1, thereby obtaining a mixture, and calcining the resultant mixture at a temperature in the range of from 600 to 1000°C under an atmosphere of at least 50% by volume of oxygen.

[0066] The inventive production process may include further steps, such as a washing step or a coating step, e.g., with a compound of tungsten or boron, preferably an oxide or (oxy) hydroxi de e.g., with WO3, H2WO4 or boric acid.

[0067] The invention is further illustrated by working examples.

[0068] General remark about the oxidation state determination: The average Mn oxidation states of precursors were determined by iodometric titration. For this purpose, a small amount of sample (~ 0.3 g) was dispersed in a 20 wt% HCI solution and the mixture was heated to evaporate into a receiver containing a 10 wt% KI solution. The iodine formed was titrated using a 0.1 M Na2S2C>3 solution. From the consumption of the thiosulfate solution, the amount of oxidized Mn was calculated and compared to the total amount of substance of Mn measured by ICP-OES.

[0069] General remarks about the spray-dryer used: The spray dryer used in the inventive examples had a diameter of 2.5 m and height of 6.5 m. The respective product suspension was fed through a pipeline from the pulper to the spray dryer and the solid was sprayed through a centrifugal atomizer, which was positioned at the top of the spray dryer. The diameter of the rotating wheel was 30 cm and had 6 nozzle outlets with a diameter of 3 cm. Via these nozzle outlets the suspension was sprayed from the top of the spray dryer into the body of the spray dryer. The dry precursor was collected in baghouse filters and gathered in a cooling containment. The dry product is then cooled down by contact cooling at room temperature.

[0070] General remark about analytics: LIV-VIS spectra were recorded in a PerkinElmer Lambda 950 with quartz cuvettes. The recordal speed was 267 nm / min.

[0071] The following aqueous solutions were provided.

[0072] Solution (a.1): Commercially available NiSCL, CoSO4 and MnSCU (all three as battery grade) dissolved in deionized water (molar ratio 91 :4.5:4.5, total transition metal concentration: 1.45 mol / kg)

[0073] Solution (p.1 ): 25wt% NaOH dissolved in deionized water

[0074] Solution (y.1): 25wt% ammonia in deionized water

[0075] 1.1 Synthesis of an inventive precursor P-CAM.1

[0076] A 10 m3stirred vessel equipped with baffles and a 45° pitch-blade stirrer, and three dosing tubes, two for an aqueous solution (a.1), one for solution (p.1 ) and one for solution (y.1), was charged with 9.5 m3of deionized water and the temperature of the vessel was set to 45°C. The vessel had a constant nitrogen overflow during all reactions.

[0077] Step (a.1-1): The stirrer element was operated at 210 rpm. Aqueous solution (a.1), (p.1) and (y.1) were simultaneously introduced into the vessel through the corresponding tubes. The molar ratio between ammonia and transition metal was adjusted to 0.25. Initially, the sum of volume flows was set to adjust the residence time to 10.0 hours. The flow rate of solution (p.1 ) was adjusted by a pH regulation circuit to keep the pH value in the stirred vessel at a constant value of 12.5 for 5 min of reaction time and thereafter was lowered to 11 .4 for the remaining time of the precipitation reaction.

[0078] Step (a.1-2): After 20 h of reaction time, the particle growth was ceased by stopping the feed dosing. The slurry obtained was collected and had an average particle diameter (D50) of 4.1 pm and (D90-D10) / D50 of 0.73. A fraction of the slurry was transferred into another 10 m3stirred tank reactor, which was equipped as described above. The slurry inside the reactor was combined with a solution (p.1 ) and (y.1 ) at pH-value of 11.8, and an ammonia concentration of 0.50 wt%. The temperature Inside the vessel was set to 65 °C, the stirrer element was operated at 210 rpm and the aqueous solution (a.1), (p.1) and (y.1 ) were simultaneously introduced into the vessel through the corresponding tubes and the particles were grown until a particle diameter of 14.0 pm was reached. The stirring speed was stepwise decreased until the end of the reaction.

[0079] Step (b.1): The resulting slurry was filtered, washed with deionized water and an aqueous solution of sodium hydroxide (1 kg of 25 wt% aqueous sodium hydroxide solution per kg of solid hydroxide. A filter cake and a filtrate were obtained.

[0080] The wet filter cake was discharged into a pulper, and the solid content was adjusted to 35 wt%.

[0081] Step (c.1): The concentrated slurry from step (b.1) was transferred to the spray dryer with an air inlet temperature of 350 °C and gas flow rate of 5500 m3 / h. This resulted in a residence time of the particles of 5 seconds at a temperature of 120 °C to obtain the inventive precursor P- CAM.1. P-CAM.1 was a green powder and had an average particle diameter (D50) of 13.8 pm, a value of (D90-D10) / D50 of 0.32, a BET surface of 8.5 m2 / g, an average oxidation state of the manganese of 2.4, a refraction maximum of 18.2% between 500 and 700 nm measured by UV- VI S spectrometry in a quartz cuvette.

[0082] 1.2 Synthesis of an inventive precursor P-CAM.2

[0083] A 10 m3stirred vessel equipped with baffles and a 45° pitch-blade stirrer, and three dosing tubes, two for an aqueous solution (a.1), one for solution (p.1 ) and one for solution (y.1), was charged with 9.5 m3of deionized water and the temperature of the vessel was set to 45°C. The vessel had a constant nitrogen overflow during all reactions.

[0084] Step (a.2-1): The stirrer element was operated at 210 rpm. Aqueous solution (a.1), (p.1) and (y.1) were simultaneously introduced into the vessel through the corresponding tubes. The molar ratio between ammonia and transition metal was adjusted to 0.25. Initially, the sum of volume flows was set to adjust the residence time to 10.0 hours. The flow rate of solution (p.1 ) was adjusted by a pH regulation circuit to keep the pH value in the stirred vessel at a constant value of 12.5 for 5 min of reaction time and thereafter was lowered to 11 .4 for the remaining time of the precipitation reaction.

[0085] Step (a.2-2): After 20 h of reaction time, the particle growth was ceased by stopping the feed dosing. The slurry obtained was collected and had an average particle diameter (D50) of 4.1 pm and (D90-D10) / D50 of 0.73. A fraction of the slurry was transferred into another 10 m3stirred tank reactor, which was equipped as described above. The slurry inside the reactor was combined with a solution (p.1 ) and (y.1 ) at pH-value of 11.7, and an ammonia concentration of 0.55 wt%. The temperature Inside the vessel was set to 65 °C, the stirrer element was operated at 210 rpm and the aqueous solution (a.1), (p.1) and (y.1) were simultaneously introduced into the vessel through the corresponding tubes and the particles were grown until a particle diameter of 14.4 pm was reached. The stirring speed was stepwise decreased until the end of the reaction.

[0086] Step (b.2): The resulting slurry was filtered, washed with deionized water and an aqueous solution of sodium hydroxide (1 kg of 25 wt% aqueous sodium hydroxide solution per kg of solid hydroxide.

[0087] Step (c.2) The wet filter cake was discharged into a pulper, and the solid content was adjusted to 35 wt%. The concentrated slurry was transferred to the spray dryer with an air inlet temperature of 350 °C and gas flow rate of 5500 m3 / h. This resulted in a residence time of the particles of 5 seconds at a temperature of 120 °C to obtain the inventive precursor P-CAM.2. P-CAM.2 was a green powder and had an average particle diameter (D50) of 14.2 pm, a value of (D90- D10) / D50 of 0.29, a BET surface of 10.2 m2 / g, an average oxidation state of manganese of 2.6, a refraction maximum of 16.8% between 500 and 700 nm measured through LIV-VIS spectrometry in a quartz cuvette.

[0088] 1.3 Synthesis of a comparative precursor C-P-CAM.3

[0089] A 10 m3stirred vessel equipped with baffles and a 45° pitch-blade stirrer, and three dosing tubes, two for an aqueous solution (a.1), one for solution (p.1 ) and one for solution (y.1), was charged with 9.5 m3of deionized water and the temperature of the vessel was set to 45°C. The vessel had a constant nitrogen overflow during all reactions.

[0090] Step (b.3-1): The stirrer element was operated at 210 rpm. Aqueous solution (a.1), (p.1) and (y.1) were simultaneously introduced into the vessel through the corresponding tubes. The molar ratio between ammonia and transition metal was adjusted to 0.25. Initially, the sum of volume flows was set to adjust the residence time to 10.0 hours. The flow rate of solution (p.1 ) was adjusted by a pH regulation circuit to keep the pH value in the stirred vessel at a constant value of 12.5 for 5 min of reaction time and thereafter was lowered to 11 .4 for the remaining time of the precipitation reaction.

[0091] Step (b.3-2): After 20 h of reaction time, the particle growth was ceased by stopping the feed dosing. The slurry obtained was collected and had an average particle diameter (D50) of 4.1 pm and (D90-D10) / D50 of 0.73. A fraction of the slurry was transferred into another 10 m3-stirred tank reactor, which was equipped as described above. The slurry inside the reactor was combined with a solution (p.1 ) and (y.1 ) at pH-value of 11.7, and an ammonia concentration of 0.55 wt%. The temperature Inside the vessel was set to 65 °C, the stirrer element was operated at 210 rpm and the aqueous solution (a.1), (p.1) and (y.1 ) were simultaneously introduced into the vessel through the corresponding tubes and the particles were grown until a particle diameter of 14.4 pm was reached. The stirring speed was stepwise decreased until the end of the reaction.

[0092] Step (b.3): The resulting slurry was filtered, washed with deionized water and an aqueous solution of sodium hydroxide (1kg of 25 wt% aqueous sodium hydroxide solution per kg of solid hydroxide).

[0093] Step C-(c.3):

[0094] The washed filter cake so obtained was dried in a box oven at 120 °C for 48 h under air to obtain the comparative precursor C-P-CAM.3. C-P-CAM.3 was a brown powder and had an average particle diameter (D50) of 14.2 pm, a value of (D90-D10) / D50 of 0.29, a BET surface of 10.2 m2 / g, an average oxidation state of manganese of 3.8, a refraction maximum of 3.60% through LIV-VIS spectrometry between 500 and 700 nm in a quartz cuvette.

[0095] Table 1: Appearance and residual moisture content in precursor material

[0096] Refr max: refraction maximum 500 to 700 nm

[0097] RMC: residual moisture content determined through Karl-Fischer titration.

[0098] II. Manufacture of inventive and comparative cathode material

[0099] 11.1 Calcination and post-treatments of inventive precursor P-CAM.1

[0100] Approximately 45 g of inventive P-CAM.1 was heated in a Linn oven for 2 hours at 450 °C under flowing air to produce the O-P-CAM.1. The O-P-CAM.1 was then mixed with LiOH monohydrate (molar ratio Li / metal=1.04), 280 mg AI(OH)3 and 230 mg ZrC>2 for 15 minutes in a grinding mill.

[0101] A saggar was charged with the resultant mixture and transferred into a Linn oven. The temperature was raised at rate of 2 C / min to 765 °C under flowing oxygen and then held constant at 765 °C for 8 hours and subsequently allowed to naturally cool under flowing oxygen. The resultant powder was deagglomerated in a grinding mill and sieved.

[0102] 30 g powder was then added to 15 ml deionized water stirred for 2 minutes and then immediately filtered on a Buchner funnel to remove water. The wet filter cake is then dried under an N2 atmosphere with reduced pressure at 120 °C for 10 hours. The resultant powder was coated with boric acid by mixing 30 g powder, mixing media and 30 mg boric acid for 40 minutes at low speed on a roller mill. A saggar is charged with the dried powder and heat treated in Linn oven. The Linn oven is heated to 300 °C for 2 hours under oxygen atmosphere and allowed to cool naturally. Inventive CAM.1 is obtained.

[0103] I I.2 Further cathode active materials

[0104] The above protocol was repeated for the manufacturing of inventive CAM.2 from the inventive P-CAM.2 and the comparative C-CAM.3 from the comparative C-P-CAM.3. A comparison of the physical properties and the electrochemical performance of the inventive and comparative cathode active materials is given in table 1.

[0105] III. T esting of Cathode Active Material

[0106] 111.1 Cathode manufacture

[0107] Positive electrode: PVDF binder (polyvinylidene difluoride, Solef® 5130) was dissolved in NMP (Merck) to produce a 7.5 wt.% solution. For electrode preparation, binder solution (2.5 wt.%), and carbon black (Li 400, 2.5 wt.-%) were suspended in NMP. After mixing using a planetary centrifugal mixer (ARE-250, Thinky Corp., Japan), either inventive CAM.2 or C-CAM.1 (95 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). Prior to use, all electrodes were calendared. The thickness of cathode material was 85 pm, corresponding to 21 mg / cm2. All electrodes were dried at 120°C for 7 hours before battery assembly.

[0108] 111.2 Electrolyte Manufacture

[0109] A base electrolyte composition was prepared containing 12.0 wt% of LiPFe, 44.0 wt% of ethylene carbonate (EC), and 44.0 wt% of di-ethyl I carbonate (DMC) (EL base 1), based on the total weight of EL base 1.

[0110] 111.3 Test cell Manufacture - coin type half cells

[0111] Coin-type half cells (20 mm in diameter and 3.2 mm in thickness) comprising a cathode prepared as described under 11.1 or 11.2 and lithium metal as working and counter electrode, respectively, were assembled and sealed in an Ar-filled glove box. In addition, the cathode and anode and a separator were superposed in order of cathode / / separator / / Li foil to produce a half coin cell. Thereafter, 0.095 mL of the EL base 1 which is described above (III.2) were introduced into the coin cell. 111.4 Evaluation of cell performance

[0112] The initial performance, C-rate performance and cycling performance were measured as follows: Coin half cells according to 111.3 were tested in a voltage range between 4.3 V to 2.7 V at room temperature. For the initial cycles, the initial lithiation was conducted in the CC-CV mode, i.e. , a constant current (CC) of 0.04 C was applied until reaching 4.3V, followed by the CV step until the current dropped to 0.01 C. After 10 min resting time, reductive lithiation was carried out at constant current of 0.04 C up to 27 V. For the C-rate test charge and discharge rates were adjusted accordingly. For the cycling tests the constant current was chosen to be 0.33 C until 56 cycles were reached.

[0113] A comparison of the physical properties of the inventive and comparative precursors is given in Table 1. A comparison of the UV-Vis spectra of the inventive precursor material P-CAM.1 and the comparative precursor material C-P-CAM.3 is given in Figure 1.

[0114] Table 1 : A comparison of the physical properties of the inventive precursor materials P-CAM.1 and P-CAM.2 and the comparative precursor material C-P-CAM.3.

[0115] Degree of cracking in composite oxide precursor material O-P-CAM and comparison of the physical properties of the CAMs electrochemical performances of the inventive and comparative cathode active materials is given in Table 2. SEM images of the inventive composite oxide precursor material O-P-CAM.1

[0116] Table 2: Degree of cracking in precursor composite oxide precursor material O-P-CAM, electrochemical performance of inventive cathode active materials CAM.1 and CAM.2 as well as comparative cathode active material C-CAM.3

Claims

Patent Claims1. Process for making a composite hydroxide of TM with an average particle diameter (d50) in the range of from 3 to 25 pm wherein TM is a combination of metals according to general formula (I),(NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.60 to 0.95, b is in the range of from 0.025 to 0.2, c is in the range of from 0.03 to 0.2, and d is in the range of from zero to 0.05, andM1is selected from Al, Ti, Zr, W, Mo, Mg, Nb, Ta, Ca, and combinations of at least two of the foregoing, a + b + c = 1 , wherein the manganese has an average oxidation state in the range of from 2.1 to 2.8, wherein said process comprises the steps of:(a) co-precipitation of a hydroxide of TM from an aqueous medium in one or more substeps,(b) recovering the precipitated hydroxide of TM as a concentrated slurry,(c) removing the water at a temperature above 100°C in a way that the exposure to air is 15 seconds or less at a temperature above 100 °C.

2. Process according to claim 1 wherein TM is a combination of metals according to general formula (I)(NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.80 to 0.94, b being in the range of from 0.025 to 0.1 , c being in the range of from 0.04 to 0.20, and d being in the range of from 0.02 to 0.05.

3. Process according to claim 1 or 2 wherein step (c) is a spray drying step.

4. Process according to any of the preceding claims wherein step (c) is performed with air as drying gas.

5. Process according to any of the preceding claims wherein the dried hydroxide of TM is after step (c) immediately quenched in a containment with a cooled air atmosphere to limit any oxidation of the material.

6. Process according to any of the preceding claims wherein step (a) is performed under an atmosphere of nitrogen or a noble gas.

7. Composite hydroxide of TM with an average particle diameter (d50) in the range of from 3 to 25 pm wherein TM is a combination of metals according to general formula (I):(NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.60 to 0.95, b is in the range of from 0.025 to 0.2, c is in the range of from 0.03 to 0.2, and d is in the range of from zero to 0.05,M1is selected from Al, Ti, Zr, W, Mo, Mg, Nb, Ta, Ca, and combinations of at least two of the foregoing, a + b + c = 1 , wherein said composite hydroxide has a moisture content in the range from 0.1 to 1.0 wt% determined by Karl-Fischer titration, and wherein the manganese in TM has an average oxidation state in the range of from 2.1 to 2.8.

8. Composite hydroxide of TM according to claim 7 wherein TM corresponds to combinations of metals according to general formula (I)(NiaCobMnc)i-dM1d (I) a is in the range of from 0.80 to 0.94,b being in the range of from 0.025 to 0.1 , c being in the range of from 0.04 to 0.20, and d being in the range of from 0.02 to 0.05.

9. Composite hydroxide of TM according to claim 7 or 8 having a refraction maximum of above 5.0% measured by UV-Vis spectrometry between 500 and 700 nm.

10. Process for making a cathode active material by mixing a composite hydroxide according to any of the claims 7 to 9 with a source of lithium and, optionally, with at least one oxide, hydroxide or oxyhydroxide of M1and calcining the resultant mixture at a temperature in the range of from 600 to 1000°C under an atmosphere of at least 50% by volume of oxygen.

11. Process for making an oxide of TM by subjecting a composite hydroxide according to any of the claims 7 to 9 to a temperature in the range of from 300 to 1000°C under an atmosphere of at least 50% by volume of oxygen in the absence of a source of lithium.

12. Composite Oxide of TM with an average particle diameter (d50) in the range of from 3 to 25 pm wherein TM contains at least 60 mol-% nickel and at least 3 mol-% manganese where the average cracked particle content is below 5%, wherein TM corresponds to combinations of metals according to general formula (I)(NiaCObMnc)i-dM1d (I) wherein a is in the range of from 0.60 to 0.95, b is in the range of from 0.025 to 0.2, c is in the range of from 0.03 to 0.2, and d is in the range of from zero to 0.05,M1is selected from Al, Ti, Zr, W, Mo, Mg, Nb, Ta, Ca, and combinations of at least two of the foregoing, a + b + c = 1.

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