The present invention is directed towards a process for making a precursor of an electrode active material comprising the steps of:

(a) making an oxide, (oxy) hydroxi de, hydroxide or carbonate comprising nickel by (co-)precip- itation in an aqueous medium,

(b) separating said oxide, (oxy) hydroxide, hydroxide or carbonate from said aqueous medium by a solid-liquid separation method,

(c) optionally, drying the solid residue from step (b) in air,

(d) applying a robot to take at least two samples of 10 mg to 10 g from the solid material from step (b) or (c), if applicable,

(e) transferring said samples to another robot or to another part of the same robot, where the respective robot transfers the samples to at least one test unit to perform measurements with respect to at least one parameter selected from

(e1) particle diameter, (e2) element distribution, and (e3) moisture content, (e4) crystallographic properties in XRD, or (e5) specific surface (BET), (e6) sulfate content.

In addition, the present invention is directed towards a set-up that is useful for carrying out the above process.

Lithium ion secondary batteries are modern devices for storing energy. Many application fields have been and are contemplated, from small devices such as mobile phones and laptop computers through car batteries and other batteries for e-mobility. Various components of the batteries have a decisive role with respect to the performance of the battery such as the electrolyte, the electrode materials, and the separator. Particular attention has been paid to the cathode materials. Several materials have been suggested, such as lithium iron phosphates, lithium cobalt oxides, and lithium nickel cobalt manganese oxides. Although extensive research has been performed the solutions found so far still leave room for improvement.

Cathode active materials are generally manufactured by using a two-stage process. In a first stage, a sparingly soluble compound of the transition metal(s) is made by precipitating it from a solution, for example a carbonate or a hydroxide. Said sparingly soluble salts are in many cases also referred to as precursors. In a second stage, a precursor is mixed with a lithium compound, for example U2CO3, LiOH or U2O, and calcined at high temperatures, for example at 600 to 1100°C.

Several technical fields are still to be solved. Volumetric energy density, capacity fade, cycling stability are still fields of research and development. However, in production additional problems have been detected. Although a constant product quality is desired sometimes the quality and the composition varies in broad ranges. Strong variation of quality, however, may lead to higher amounts of product not meeting the specification, hereinafter also referred to as “off-spec” material, and to a cost increase. In many cases, the quality of the precursor is responsible for a cathode active material not meeting the specified quality.

It was therefore an objective to provide a process that leads to a more homogeneous product quality in the manufacture of electrode active materials and especially of the respective precursors and to a reduced amount of off-spec material.

Accordingly, the process defined at the outset has been found, hereinafter also referred to as “inventive process” or as “process according to the (present) invention”. The inventive process comprises a sequence of several steps as defined at the outset, hereinafter also defined as step (a), step (b), step (c) etc. The inventive process will be described in more detail below. Step (b) is an optional step.

In step (a), a precursor is made, selected from oxides, (oxy)hydroxides, oxides and carbonates comprising nickel and preferably selected from composite oxides, composite (oxy)hydroxides and composite carbonates comprising nickel. In embodiments wherein such precursors are nickel (oxy) hydroxi de or nickel oxide, such precursors are preferably made by precipitating a nickel hydroxide from an aqueous solution of nickel sulfate with an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, followed by drying in air. In embodiments wherein such precursors comprise at least one metal other than nickel, for example cobalt or manganese, such precursor is a composite oxide, composite (oxy)hydroxide or composite carbonate.

Preferably, said precursor comprises nickel and at least one of cobalt and manganese and, optionally, at least one of Mg, Al and Y or a transition metal selected from Ti, Zr, Nb, Ta, Fe, Mo, and W.

In one embodiment of the present invention, said precursor is obtained by (co-)precipitating nickel and at least one of cobalt and manganese as carbonates from an aqueous solution containing water-soluble salts of nickel and at least one of cobalt and manganese, with an alkali metal (bi)carbonate. Water-soluble salts in the context of the present invention are salts with a solubility of at least 50 g/l at 20°C. Examples are nitrates, acetates, halides such as chlorides and bromides and especially the sulphates. The amounts of nitrates, acetates or preferably sulfates of nickel and at least one of cobalt and manganese are applied in a stoichiometric ratio corresponding to TM. Said co-preci pitation may be accomplished by the addition of alkali metal (bi)carbonate to the above solution, for example an aqueous solution of potassium bicarbonate, potassium carbonate, sodium bicarbonate or sodium carbonate, in a continuous, semi-continu- ous or batch process. Said co-precipitation is then followed by removal of the mother liquor, for example by filtration, and subsequent removal of water.

Said precursor is preferably obtained by co-precipitating nickel and at least one of cobalt and manganese as hydroxides from an aqueous solution containing water- Examples are nitrates, acetates, halides such as chlorides and bromides and especially the sulphates. The amount of nitrates, acetates or preferably sulfates of nickel and at least one of cobalt and manganese are applied in a stoichiometric ratio corresponding to TM. Said co-precipitation may be accomplished by the addition of alkali metal hydroxide to the above solution, for example an aqueous solution of potassium hydroxide or sodium hydroxide, in a continuous, semi-continuous or batch process. Said co-precipitation is then followed by removal of the mother liquor, for example by filtration, and subsequent removal of water.

Said precursor is made in particulate form. In one embodiment of the present invention, the mean particle diameter (D50) of precursor (A) is in the range of from 2 to 20 pm, preferably 3 to 16 pm, more preferably 7 to 10 pm. The mean particle diameter (D50) in the context of the present invention refers to the median of the volume-based particle diameter, as can be determined, for example, by light scattering. In one embodiment, the precursor has a monomodal particle diameter distribution. In other embodiments, the particle distribution of the precursor may be bimodal, for example with one maximum in the range of from 1 to 5 pm and a further maximum in the range of from 7 to 16 pm.

The particle shape of the secondary particles of said precursor is preferably spheroidal, that are particles that have a spherical shape. Spherical spheroidal shall include not just those which are exactly spherical but also those particles in which the maximum and minimum diameter of at least 90% (number average) of a representative sample differ by not more than 10%.

In one embodiment of the present invention, said precursor is comprised of secondary particles that are agglomerates of primary particles. Preferably, said precursor is comprised of spherical secondary particles that are agglomerates of primary particles. Even more preferably, said precursor is comprised of spherical secondary particles that are agglomerates of spherical primary particles or platelets.

In one embodiment of the present invention, said precursor may have a particle diameter distribution span in the range of from 0.5 to 0.9, the span being defined as [(D90) - (D10)] divided by (D50), all being determined by LASER analysis. In another embodiment of the present invention, said precursor may have a particle diameter distribution span in the range of from 1 .1 to 1.8.

In one embodiment of the present invention the specific surface (BET) of said precursor is in the range of from 2 to 10 m ² /g or even 15 to 100 m ² /g, determined by nitrogen adsorption, for example in accordance with to DIN-ISO 9277:2003-05.

In one embodiment of the present invention, said precursor may be characterized by crystallographic properties obtainable by X-ray diffraction, for example a c value in the range of from 4.55 to 4.7 A Typical peaks in an X-ray diagram (Cu-Ka) have 20 (2Theta) values of 001 at 19.0 to 19.4

100 at 33.0 to 34.3

101 at 38.0 to 39.5

102 at 52.0 to 53.2

110 at 59 to 61.2

111 at 62 to 65.1.

In one embodiment of the present invention said precursor may have a homogeneous distribution of the transition metals nickel, cobalt and manganese over the diameter of the particles. In other embodiments of the present invention, the distribution of at least two of nickel, cobalt and manganese is non-homogeneous, for example exhibiting a gradient of nickel and manganese, or showing layers of different concentrations of at least two of nickel, cobalt and manganese. It is preferred that said precursor has a homogeneous distribution of the transition metals over the diameter of particles.

In one embodiment of the present invention, said precursor may contain elements other than nickel and at least one of cobalt and manganese, for example at least one of Mg, Al and Y or a transition metal selected from Ti, Zr, Nb, Ta, Fe, Mo, and W, for example in amounts of 0.1 to 5% by mole, referring to TM. However, it is preferred that precursor (A) only contains negligible amounts of elements other nickel, cobalt and manganese, for example detection level up to 0.05% by mole. Said precursor may contain traces of metal ions, 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.

In one embodiment of the present invention, said precursor contains one or more impurities such as residual sulphate in case such precursor has been made by co-precipitation from a solution of one or more sulphates of nickel, cobalt and manganese. The sulphate may be in the range of from 0.1 to 0.4% by weight, referring to the entire precursor.

In one embodiment of the present invention, said precursor is an oxide, oxyhydroxide or hydroxide of TM, with TM being of the general formula (I)

(NiaCo _b Mn _c )i-dM _d (I) with a being in the range of from 0.6 to 0.95, preferably 0.6 to 0.9, b being in the range of from 0.025 to 0.2, preferably 0.03 to 0.12, c being in the range of from 0.025 to 0.2, preferably 0.04 to 0.1 , and d being in the range of from zero to 0.1 , preferably from 0.005 to 0.1 , and M is Al, Ti, Zr, or a combination of at least two of the foregoing, and a + b + c = 1.

Optionally, at least one dopant selected from water-soluble compounds of at least one of Mg, Al, Y, Ti, Zr, Nb, Ta, Fe, Mo, and W may be added during co-precipitation.

In one embodiment of the present invention, said precursor is an oxide, oxyhydroxide or hydroxide or carbonate of TM, with TM being of the general formula (I)

(NiaCo _b Mn _c )i-dM _d (I) with a being in the range of from 0.3 to 0.4, b being in the range of from zero to 0.1 , c being in the range of from 0.6 to 0.7, d being in the range of from zero to 0.1, preferably from 0.005 to 0.1, and M is Al, Ti, Zr, or a combination of at least two of the foregoing, and a + b + c = 1.

Optionally, at least one dopant selected from water-soluble compounds of at least one of Mg, Al, Y, Ti, Zr, Nb, Ta, Fe, Mo, and W may be added during co-precipitation.

By performing step (a), an aqueous slurry of a precursor is formed.

In step (b), said oxide, (oxy) hydroxide, hydroxide or carbonate is removed from said aqueous medium by a solid-liquid separation method, for example by filtration or a centrifuge. Filtration methods are known per se, and they may be supported by washing steps.

In the optional step (c), the solid residue - which may be the filter cake in case of a filtration - may be dried in air. Suitable drying temperatures are in the range of from 80 to 200°C, preferably 105 to 150°C.

In one embodiment of the present invention, step (c) may be performed at reduced pressure, for example 200 to 500 mbar. In other embodiments, step (c) is performed at ambient pressure.

A solid material is obtained from step (b) or - if applicable - from step (c). Such solid material may be used as precursor.

For performing step (d), a robot is applied. Said robot takes at least two samples of from 10 mg to 10 g, preferably 20 mg to 5 g and even more preferably 100 mg to 2 g per unit to be analyzed, for example per 30 minutes up to per day in a continuous process, or per batch or filter cake, preferably 3 to 5. The more samples are taken the more it is ensured that the samples provide a representative average of the overall precursor. However, if too many samples are taken too much precursor is spent for analyses.

In a preferred embodiment, the samples taken from the same batch or filter cake or cake are combined and intimately mixed by the robot before further analysis. The robot may assign numbers to the combined samples to be analyzed and may then combine such number with the respective number of the batch or filter cake, respectively, to enable tracing a sample.

In other embodiments, no numbers are assigned to batches or filter cakes or the like, and simply a trend of results in steps (e) is determined. If said trend shows that the samples miss the specification, the robot reacts as characterized below.

The robot can take the samples with a robotic arm that holds a device such as a spatula, a spoon-shaped instrument or the like for taking said samples.

In step (e), the robot transfers the samples to another robot or to another part of itself where the respective robot transfers said samples to at least one test unit to perform measurements. In the context of the present invention and unless specifically indicated otherwise, there will not be made any distinction between the “another part” of the same robot that withdraws samples, and second and thus different robot that carries out the analyses or transfers to the unit that carries out the syntheses.

In a preferred embodiment, the robot performs step (e) with several samples in parallel, for example, with 2 to 12 samples.

A further aspect of the present invention is directed towards a set-up of devices, hereinafter also referred to as inventive set-up, wherein said set-up comprises a robot, for example a synthesis robot, with a device for taking samples 10 mg to 10 g of precursor, and a means for transferring the electrode material mix to a test unit to perform tests.

In a preferred embodiment of the present invention, the inventive set-up further comprises a processing device that performs the documentation of step (e) of the inventive process and that compares the results of electrochemical tests to the desired results.

In a preferred embodiment of the present invention, the inventive set-up further comprises a processing device that collects data as input through an input channel and provides an electronic signal via an output channel to a production control function in case at least two consecutive samples show a deviation from the desired results, the term “desired results” being explained above. In one embodiment of the present invention, the precursor is characterized by at least one parameter, preferably at least two parameters selected from

(e1) particle diameter,

(e2) element distribution,

(e3) moisture content,

(e4) crystallographic properties in XRD,

(e5) specific surface (BET), or

(e6) sulfate content.

The particle diameter (e1) - as referred herein - may be defined as the average particle diameter (D50) as determined by dynamic light scattering, preferably with an autosampler, or by LASER diffraction or electroacoustic spectroscopy and refers to the volume-based average.

In one embodiment of the present invention, the particle diameter (e1) also includes a specification with respect to the width of the particle diameter distribution, for example expressed as [(D90) - (D10)]/(D50).

In one embodiment of the present invention, the particle diameter (e1) includes information about further features of the particle diameter distribution, for example information whether the particle diameter distribution is mono-modal or bimodal or multimodal.

The element distribution may be determined by X-ray fluorescence, atomic emission spectroscopy, atomic absorption spectroscopy or by scanning electron microscopy and EDS or by combinations of the forgoing methods. Further details of the element distribution (e2) has been discussed above.

The moisture content (e3) includes physisorbed (adsorbed) and preferably chemically bound water. Its knowledge is of importance for properly calculating the amount of lithium source before calcination. The moisture content (e3) may be determined by Karl-Fischer titration. Preferably, the moisture content (e3) is determined by Karl-Fischer titration in an automatic titration device. The moisture content (e3) may be in the range of from 5 to 1 ,000 ppm of water, ppm being ppm by weight.

Crystallographic properties (e4) from XRD, for example lattice parameters, are dependent on elemental composition, secondary particle diameter, primary particle diameter, crystallographic strain, degree of crystallinity, for example the c axis, the a axis, impurities. Examples are breadth and shape of peaks in the XRD diagrams.

The specific surface (BET) - hereinafter also referred to as BET surface (e5) - of precursors may be in the range of from 1 to 80 m ² /g, preferably 5 to 80 m ² /g. The BET surface (e.5) may be determined by automatic devices with autosamplers.

The sulfate content (e6) may be determined by ion chromatography. It may be expressed in wt % or % by weight and refer to sulfate or to S. It is preferred if the sulfate content does not exceed 0.5% by weight, preferably 0.4% by weight of the precursor. A suitable lower limit is 0.1% by weight of sulfate, referring to precursor.

In one embodiment of the present invention, the inventive process comprises an additional step of taking samples of the filtrate or of the slurry before a filtration. The filtrate may be analyzed, e.g., for metal ions, especially nickel and, if applicable, for cobalt.

A further aspect of the present invention is directed towards a set-up of devices, hereinafter also referred to as inventive set-up, wherein said set-up comprises a synthesis robot with a device for taking samples 10 mg to 10 g of precursor, a means for transferring said samples to another robot or to another part of the same robot, to at least one test unit to perform measurements with respect to at least one parameter selected from (e1) particle diameter, (e2) element distribution, and (e3) moisture content

(e4) crystallographic properties in XRD, or

(e5) specific surface (BET), (e6) sulfate content.

In a preferred embodiment, the inventive set-up further comprises a processing device that collects data of any of steps (e1) to (e6) as input through an input channel and compares the results of electrochemical tests to the targeted results stored in said processing device. Examples of processing devices are computers. As mentioned herein, the term “computer” may refer to a single computer or to a plurality of computers that are working together to perform the above function.

In one embodiment of the present invention, the inventive set-up further comprises a processing device that collects data as input through an input channel and provides an electronic signal via an output channel to a production control function in case that at least two consecutive samples show a significant deviation from the targeted results stored in said processing device.

In one embodiment of the present invention, the inventive set-up further contains a model that links measurement (e1) to (e6) with process parameters of step (a), based on stored data, and thus relating the data of said measurement(s) of any of (e1) to (e6) to at least one of pH value, nickel and other metal contents, and stirring speed, and drying parameters such as temperature and drying time. Specifically, such said processing device in inventive set-ups may derive adapted process parameters based on the comparison of the model and the operating conditions in place when off-spec samples have been taken.

The present invention is further illustrated by working examples.

I. Providing Precursors

1.1 Synthesis of a precursor TM-OH.1 , steps (a.1) to (c.1)

A stirred tank reactor was filled with deionized water and tempered to 55 °C and a pH value of 12 was adjusted by adding an aqueous sodium hydroxide solution.

The co-precipitation reaction was started by simultaneously feeding an aqueous transition metal sulfate solution and aqueous sodium hydroxide solution at a flow rate ratio of 1.9, and a total flow rate resulting in an average residence time of 8 hours. The transition metal solution contained Ni, Co and Mn at a molar ratio of 6:2:2 and a total transition metal concentration of 1.65 mol/kg. The aqueous sodium hydroxide solution was a 25 wt.% sodium hydroxide solution. The pH value was kept at 11.9 by the separate feed of an aqueous sodium hydroxide solution. After stabilization of particle size the resulting suspension was removed continuously from the stirred vessel. The mixed transition metal (TM) oxyhydroxide precursor TM-OH.1 was obtained by filtration of the resulting suspension, washing with distilled water, drying at 120°C in air and sieving. The average particle diameter (D50) was 10 pm.

1.2 Synthesis of a precursor TM-OH.2, steps (a.2) to (c.2)

A stirred tank reactor was filled with deionized water and 49 g of ammonium sulfate per kg of water. The solution was tempered to 55 °C and a pH value of 12 was adjusted by adding an aqueous sodium hydroxide solution. The co-precipitation reaction was started by simultaneously feeding an aqueous transition metal sulfate solution and aqueous sodium hydroxide solution at a flow rate ratio of 1.8, and a total flow rate resulting in an average residence time of 8 hours. The transition metal solution contained Ni, Co and Mn at a molar ratio of 8:1 :1 and a total transition metal concentration of 1.65 mol/kg. The aqueous sodium hydroxide solution was a 25 wt.% sodium hydroxide solution and 25 wt.% ammonia solution in a weight ratio of 6. The pH value was kept at 12 by the separate feed of an aqueous sodium hydroxide solution. Beginning with the start-up of all feeds, mother liquor was removed continuously. After 33 hours all feed flows were stopped. The mixed transition metal (TM) oxyhydroxide precursor TM-OH.2 was obtained by filtration of the resulting suspension, washing with distilled water, drying at 120°C in air and sieving. The average particle diameter (D50) was 10 pm.

Step (d.1)

After step (c.1), respectively, a robotic arm takes several small samples of 1 g TM-OH.1 each from the dried material. For this propose, the samples are portioned by a robotic arm in vessels and another robotic arm closes the cap of the vessels to avoid carbon dioxide uptake. The closed vessels are then transferred to different sections to carry out the analytics and electrode processing.

Steps (e3.1), (e4.1), and (e5.1):

One vessel of 1 g of TM-OH.1 is transferred to an automated XRD device to measure the powder diffraction pattern of the sample. Another portion of 1 g sample of TM-OH.1 is transferred to an automated Karl-Fischer titration device to measure the moisture content of TM-OH.1 material and another 5 g TM-OH.1 are used for the automated BET surface measurement.

A computer compares the test results to the specified results. If all parameters are within the desired specification the production process does not need to be adapted.

Step (d.2)

After step (c.2), respectively, a robotic arm takes several small samples of 1 g TM-OH.2 each from the dried material. For this propose, the samples are portioned by a robotic arm in vessels and another robotic arm closes the cap of the vessels to avoid carbon dioxide uptake. The closed vessels are then transferred to different sections to carry out the analytics and electrode processing. Steps (e3.2), (e4.2), and (e5.2):

One vessel of 1 g of TM-OH.2 is transferred to an automated XRD device to measure the powder diffraction pattern of the sample. Another portion of 1 g sample of TM-OH.1 is transferred to an automated Karl-Fischer titration device to measure the moisture content of TM-OH.1 material and another 5 g TM-OH.2 are used for the automated BET surface measurement.

A computer compares the test results to the specified results. If all parameters are within the desired specification the production process does not need to be adapted. In case of significant deviations from the specification in at least two consecutive tests, the computer provides an electronic signal via an output channel to a production control function, and the manufacture of off-spec material can be stopped fast.