JP2023539886A - Method for producing electrode active material precursor - Google Patents

Abstract

The following steps: (a) producing nickel-containing oxides, (oxy)hydroxides, hydroxides or carbonates by (co)precipitation in an aqueous medium; and (b) solid-liquid separation. (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, if applicable, step (c); and (e) transferring said sample to another robot or another part of the same robot, each robot transferring the sample to at least one test unit to determine (e1) particle size, (e2) elemental distribution, and (e3) water content, (e4) crystallographic properties in XRD, or (e5) specific surface area (BET), and (e6) sulfate content. , a method for producing a precursor of an electrode active material.

Description

The present invention includes the following steps:
(a) producing a nickel-containing oxide, (oxy)hydroxide, hydroxide or carbonate by (co)precipitation in an aqueous medium;
(b) separating the oxide, (oxy)hydroxide, hydroxide or carbonate from the 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, if applicable, from step (c);
(e) transferring the sample to another robot or another part of the same robot, each robot transferring the sample to at least one test unit;
(e1) particle size,
(e2) elemental distribution, and (e3) water content,
(e4) Crystallographic properties in XRD, or (e5) Specific surface area (BET),
(e6) Sulfate content The present invention relates to a method for producing a precursor of an electrode active material, the method comprising: measuring at least one parameter selected from: (e6) content of sulfate;

Furthermore, the invention relates to a set-up useful for carrying out the above method.

Lithium-ion secondary batteries are modern devices for storing energy. Many applications have been considered, from small devices such as mobile phones and laptop computers to car batteries and other e-mobility batteries. Various battery components such as electrolytes, electrode materials, and separators have important roles in battery performance. Cathode materials have received particular attention. Several materials have been proposed, such as lithium iron phosphate, lithium cobalt oxide, and lithium nickel cobalt manganese oxide. Although extensive research studies have been conducted, the solutions found so far still leave room for improvement.

Cathode active materials are generally manufactured using a two-step process. In the first step, poorly soluble compounds of the transition metal(s) are prepared by precipitating them from solution, such as carbonates or hydroxides. The poorly soluble salt is often also called a precursor. In the second step, the precursor is mixed with a lithium compound, for example Li ₂ CO ₃ , LiOH or Li ₂ O, and calcined at a high temperature, for example 600-1100°C.

Some technical areas are still unresolved. Volumetric energy density, capacity drop, cycle stability, etc. are areas where there is still room for research and development. However, additional problems have been found in manufacturing. Although it is desirable that the quality of the product be constant, sometimes the quality and composition can vary over a wide range. However, if there are large variations in quality, there will be a large number of products that do not meet the specifications (hereinafter also referred to as "substandard" materials), which may increase costs. Substandard quality of cathode active materials is often due to the quality of the precursor.

The aim of the present invention was therefore to provide a method that leads to a more homogeneous product quality and reduces the amount of substandard material in the production of electrode active materials, in particular their respective precursors.

There has therefore been found a method as defined at the outset, which is also referred to below as "method of the invention" or "method according to the invention". The method of the invention comprises a series of several steps as defined at the beginning, also defined below as step (a), step (b), step (c), etc. The method of the present invention will be explained in more detail below. Step (b) is an optional step.

In step (a), the compound is selected from nickel-containing oxides, (oxy)hydroxides, oxides and carbonates, preferably selected from nickel-containing composite oxides, composite (oxy)hydroxides and composite carbonates. A precursor is produced. In embodiments where such precursor is nickel (oxy)hydroxide or nickel oxide, such precursor is preferably oxidized to nickel sulfate using an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. It is produced by precipitating nickel hydroxide from an aqueous solution of nickel hydroxide followed by drying in air. In embodiments where such precursors include at least one metal other than nickel, such as cobalt or manganese, such precursors are complex oxides, complex (oxy)hydroxides or complex carbonates.

Preferably, the precursor comprises nickel, 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. including.

In one embodiment of the invention, the precursor is an alkali metal (bi)carbonate from an aqueous solution containing nickel and at least one water-soluble salt of cobalt and manganese. It is obtained by (co)precipitation of the carbonate. Water-soluble salts in the context of the present invention are salts with a solubility at 20° C. of at least 50 g/l. Examples include halides such as nitrates, acetates, chlorides and bromides, especially sulfates. The amounts of nitrate, acetate or preferably sulphate of nickel and at least one of cobalt and manganese are applied in stoichiometric ratios corresponding to the TM. Said coprecipitation may be achieved by adding an alkali metal (bi)carbonate to said solution, for example an aqueous solution of potassium bicarbonate, potassium carbonate, sodium bicarbonate or sodium carbonate, in a continuous, semi-continuous or batch process. can. Then, following the coprecipitation, the mother liquor is removed, for example by filtration, and the water is subsequently removed.

The precursor is preferably obtained by coprecipitating nickel and at least one of cobalt and manganese as hydroxide from an aqueous solution containing water. Examples include halides such as nitrates, acetates, chlorides and bromides, especially sulfates. The amounts of nitrate, acetate or preferably sulphate of nickel and at least one of cobalt and manganese are applied in stoichiometric ratios corresponding to the TM. Said coprecipitation can be achieved by adding an alkali metal hydroxide to said solution, for example an aqueous solution of potassium hydroxide or sodium hydroxide, in a continuous, semi-continuous or batch process. Then, following the coprecipitation, the mother liquor is removed, for example by filtration, and the water is subsequently removed.

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

The particle shape of the secondary particles of the precursor is preferably a spherical particle having a spherical shape. Spherical spheres include not only exactly spherical particles, but also particles whose maximum and minimum diameters differ by no more than 10% in at least 90% (number average) of a representative sample.

In one embodiment of the invention, the precursor is composed of secondary particles that are aggregates of primary particles. Preferably, the precursor is composed of spherical secondary particles that are aggregates of primary particles. Even more preferably, the precursor is composed of spherical primary particles or spherical secondary particles that are aggregates of platelets.

In one embodiment of the invention, the precursor may have a particle size distribution span ranging from 0.5 to 0.9, which span ranges from [(D90)-(D10)] to (D50) , all determined by LASER analysis. In another embodiment of the invention, the precursor may have a particle size distribution span ranging from 1.1 to 1.8.

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

In one embodiment of the invention, said precursor may be characterized by crystallographic properties obtained by X-ray diffraction, eg c-value in the range 4.55-4.7 Å. A typical peak in the X-ray diagram (Cu-Kα) is
001 from 19.0 to 19.4,
100 between 33.0 and 34.3;
101 at 38.0-39.5,
102 at 52.0-53.2,
110 at 59-61.2,
111 with 62-65.1
It has a 2Θ (2 theta) value of .

In one embodiment of the invention, the precursor may have a homogeneous distribution of the transition metals nickel, cobalt and manganese across the particle diameter. In another embodiment of the invention, the distributions of at least two of nickel, cobalt and manganese are non-homogeneous, for example exhibiting a gradient of nickel and manganese, or layers of at least two different concentrations of nickel, cobalt and manganese. show. Preferably, the precursor has a homogeneous distribution of transition metal over the particle diameter.

In one embodiment of the invention, the precursor comprises at least one element other than nickel and at least one of cobalt and manganese, such as at least one of Mg, Al and Y or Ti, Zr, Nb, Ta, Fe, Mo. and W may be contained in an amount of 0.1 to 5 mol % based on TM. Preferably, however, precursor (A) contains elements other than nickel, cobalt and manganese in negligible amounts, for example at detectable levels of 0.05 mol% or less.

The precursor may contain trace amounts of metal ions as impurities, such as traces of ubiquitous metals such as sodium, calcium, iron or zinc, but such trace amounts are not considered in the context of the present invention. Trace in this context means an amount of 0.05 mol % or less relative to the total metal content of the TM.

In one embodiment of the invention, said precursor is made by co-precipitation from a solution of one or more sulfates of nickel, cobalt and manganese, such as residual sulfates. Contains one or more impurities. The sulfate may range from 0.1 to 0.4% by weight, based on the total precursor.

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

(Ni _a Co _b Mn _c ) _1-d M _d (I)

(wherein a is in the range of 0.6 to 0.95, preferably 0.6 to 0.9,
b is in the range of 0.025 to 0.2, preferably 0.03 to 0.12,
c is in the range of 0.025 to 0.2, preferably 0.04 to 0.1,
d is in the range of 0 to 0.1, preferably 0.005 to 0.1,
M is Al, Ti, Zr, or a combination of at least two of the above,
a+b+c=1).

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

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

(Ni _a Co _b Mn _c ) _1-d M _d (I)

(In the formula, a is in the range of 0.3 to 0.4,
b is in the range of 0 to 0.1,
c is in the range of 0.6 to 0.7,
d is in the range of 0 to 0.1, preferably 0.005 to 0.1,
M is Al, Ti, Zr, or a combination of at least two of the above,
a+b+c=1).

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

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

In step (b), the oxide, (oxy)hydroxide, hydroxide or carbonate is removed from the aqueous medium by solid-liquid separation methods, such as filtration or centrifugation. Filtration methods are known per se and they may be supported by washing steps.

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

In one embodiment of the invention, step (c) may be carried out under reduced pressure, for example between 200 and 500 mbar. In other embodiments, step (c) is performed under normal pressure.

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

A robot is applied to perform step (d). Said robot analyzes at least two samples of 10 mg to 10 g, preferably 20 mg to 5 g, even more preferably 100 mg to 2 g per unit to be analyzed, for example per 30 minutes to 1 day in a continuous process, or per batch or filter cake. , preferably 3 to 5 pieces. The greater the number of samples taken, the more guaranteed that the samples provide a representative average value for the entire precursor. However, if too many samples are taken, too much precursor is used for analysis.

In a preferred embodiment, samples taken from the same batch or filter cake or cakes are combined and intimately mixed by a robot before further analysis.

The robot can assign a number to the combined sample being analyzed and then combine that number with the respective number of the batch or filter cake to enable tracking of the sample.

In other embodiments, the batches, filter cakes, etc. are not numbered and the trends in the results of step (e) are simply determined. If the trend indicates that the sample does not meet specifications, the robot reacts (acts) as characterized below.

The robot can collect the sample with a robotic arm that holds a device such as a spatula, spoon-like instrument, etc. for collecting the sample.

In step (e), the robot transfers the sample to another robot or another part of itself, each robot transferring said sample to at least one test unit and performing measurements. In the context of the present invention, unless otherwise specified, "another part" of the same robot that takes the sample and a second and therefore different robot that performs the analysis or transports it to the unit that performs the synthesis. No distinction is made between them.

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

A further aspect of the invention relates to a device setup, hereinafter also referred to as an inventive setup, wherein said setup comprises a robot, such as a synthesis robot, equipped with a device for taking 10 mg to 10 g precursor samples, and an electrode material mixture. and means for transporting the test unit to the test unit for testing.

In a preferred embodiment of the invention, the set-up of the invention further comprises a processing device for carrying out the description of step (e) of the method of the invention and for comparing the results of the electrochemical tests with target values.

In a preferred embodiment of the invention, the inventive setup collects data as input via an input channel and provides a production control function via an output channel if at least two consecutive samples show a deviation from the target value. further comprising a processing device for providing an electronic signal to the device, the term “target value” being as explained above.

In one embodiment of the invention, the precursor is
(e1) particle size,
(e2) Element distribution,
(e3) moisture content,
(e4) Crystallographic properties in XRD,
Characterized by at least one parameter, preferably at least two parameters selected from (e5) specific surface area (BET), or (e6) sulfate content.

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

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

In one embodiment of the invention, the particle size (e1) comprises information regarding further characteristics of the particle size distribution, for example whether the particle size distribution is unimodal or bimodal or multimodal.

Elemental distribution can be determined by X-ray fluorescence, atomic emission spectroscopy, atomic absorption spectroscopy, or scanning electron microscopy and EDS, or a combination of the above methods. Further details of the element distribution (e2) are as described above.

The water content (e3) includes physically adsorbed (adsorbed) water and preferably chemically bound water. That knowledge is important to properly calculate the amount of lithium source before firing. Water content (e3) can be measured by Karl Fischer titration. Preferably, the water content (e3) is determined by Karl Fischer titration in an automatic titrator. The moisture content (e3) may range from 5 to 1,000 ppm of moisture, where ppm is ppm by weight.

Crystallographic properties (e4) from XRD, e.g. lattice constant, depend on elemental composition, secondary grain size, primary grain size, crystallographic strain, crystallinity, e.g. c-axis, a-axis, impurities. Examples include the width and shape of peaks in XRD diagrams.

The specific surface area (BET) (hereinafter also referred to as BET surface area (e5)) of the precursor may range from 1 to 80 m ² /g, preferably from 5 to 80 m ² /g. BET surface area (e.5) can be measured by an automatic device equipped with an autosampler.

The sulfate content (e6) can be measured by ion chromatography. It is expressed in wt% or mass% and is relative to sulfate or S. It is preferred that the content of sulfate does not exceed 0.5% by weight, preferably 0.4% by weight of the precursor. A preferred lower limit is 0.1% by weight of sulfate, based on the precursor.

In one embodiment of the invention, the method of the invention includes the additional step of taking a sample of the filtrate or slurry prior to filtration. The filtrate may, for example, be analyzed for metal ions, particularly nickel and, if applicable, cobalt.

A further aspect of the invention relates to a device setup, also referred to below as an inventive setup, wherein said setup comprises a synthetic robot comprising a device for taking a precursor sample of 10 mg to 10 g, and said sample being transferred to another robot. or to another part of the same robot, at least one test unit;
(e1) particle size,
(e2) elemental distribution, and (e3) water content,
(e4) Crystallographic properties in XRD, or (e5) Specific surface area (BET),
(e6) Sulfate content.

In a preferred embodiment, the setup of the invention collects the data of any of steps (e1) to (e6) as input via an input channel and transfers the results of the electrochemical test to the target value stored in said processing device. further comprising a processing device for comparison. An example of a processing device is a computer. As referred to herein, the term "computer" can refer to a single computer or multiple computers that work together to perform the functions described above.

In one embodiment of the invention, the inventive setup collects data as input via an input channel, and at least two consecutive samples showed a significant deviation from a target value stored in said processing device. In some cases, the apparatus further includes a processing device that provides electronic signals to the production control function via the output channel.

In one embodiment of the invention, the inventive setup combines the measured values (e1) to (e6) with the process parameters of step (a) based on the stored data, thus (e1) to ( e6) a model relating the data of any of said measurement(s) to at least one of the drying parameters, such as pH value, nickel and other metal content, stirring rate, and temperature and drying time; Further contains. In particular, such a processing device in the inventive set-up is able to derive adapted process parameters based on a comparison with the model and the operating conditions when an out-of-spec sample is taken.

The invention is further illustrated by examples.

I. Providing Precursors I. 1 Precursor TM-OH. Synthesis of 1, steps (a.1) to (c.1)
A stirred tank reactor was filled with deionized water, heated to 55° C. and the pH value was adjusted to 12 by adding aqueous sodium hydroxide solution.

The coprecipitation reaction was started by simultaneously supplying the transition metal sulfate aqueous solution and the sodium hydroxide aqueous solution at a flow rate ratio of 1.9, and making the total flow rate an average residence time of 8 hours. The transition metal solution contained Ni, Co and Mn in 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% by mass sodium hydroxide solution. The pH value was maintained at 11.9 by separately feeding an aqueous sodium hydroxide solution. After the particle size stabilized, the resulting suspension was continuously removed from the stirring vessel. The resulting suspension was filtered, washed with distilled water, dried in air at 120° C. and sieved to remove the mixed transition metal (TM) oxyhydroxide precursor TM-OH. I got 1. The average particle size (D50) was 10 μm.

I. 2 Precursor TM-OH. Synthesis of 2, steps (a.2) to (c.2)
A stirred tank reactor was charged with deionized water and 49 g ammonium sulfate per kg water. The solution was heated to 55° C. and the pH value was adjusted to 12 by adding aqueous sodium hydroxide solution.

The coprecipitation reaction was started by simultaneously supplying the transition metal sulfate aqueous solution and the sodium hydroxide aqueous solution at a flow rate ratio of 1.8, and making the total flow rate an average residence time of 8 hours. The transition metal solution contained Ni, Co and Mn in 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% by mass sodium hydroxide solution and a 25% by mass ammonia solution in a mass ratio of 6. The pH value was maintained at 12 by separately feeding an aqueous sodium hydroxide solution. Starting from the start of all feeds, mother liquor was removed continuously. After 33 hours, all feed flows were stopped. The resulting suspension was filtered, washed with distilled water, dried in air at 120° C. and sieved to remove the mixed transition metal (TM) oxyhydroxide precursor TM-OH. I got 2. The average particle size (D50) was 10 μm.

Process (d.1)
After step (c.1), the robot arm collects 1 g of TM-OH. Multiple small samples of 1 were taken. For this proposal, the sample was aliquoted by a robotic arm inside a container, and another robotic arm capped the container to avoid carbon dioxide uptake. The closed container was then transferred to various sections for analysis and electrode processing.

Steps (e3.1), (e4.1) and (e5.1):
1 g of TM-OH. One container of 1 was transferred to an automatic XRD machine to measure the powder diffraction pattern of the sample. Another 1 g of TM-OH. One sample was transferred to an automatic Karl Fischer titrator and TM-OH. The moisture content of one material was measured and another 5 g of TM-OH. 1 was used for automated BET surface area measurements.

A computer compared the test results to specific results. If all parameters are within desired specifications, there is no need to change the manufacturing process.

Process (d.2)
After step (c.2), the robot arm collects 1 g of TM-OH. Multiple small samples of 2 were taken. For this proposal, the sample was aliquoted by a robotic arm inside a container, and another robotic arm capped the container to avoid carbon dioxide uptake. The closed container was then transferred to various sections for analysis and electrode processing.

Steps (e3.2), (e4.2) and (e5.2):
1 g of TM-OH. One container of 2 was transferred to an automatic XRD machine to measure the powder diffraction pattern of the sample. Another 1 g of TM-OH. One sample was transferred to an automatic Karl Fischer titrator and TM-OH. The moisture content of one material was measured and another 5 g of TM-OH. 2 was used for automated BET surface area measurements.

A computer compared the test results to specific results. If all parameters are within desired specifications, there is no need to change the manufacturing process.

If the material deviates significantly from specification in at least two consecutive tests, the computer can send an electronic signal via an output channel to a production control function to quickly halt production of the out-of-spec material.

Claims (15)

The following steps:
(a) producing a nickel-containing oxide, (oxy)hydroxide, hydroxide or carbonate by (co)precipitation in an aqueous medium;
(b) separating the oxide, (oxy)hydroxide, hydroxide or carbonate from the 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, if applicable, from step (c);
(e) transferring the sample to another robot or another part of the same robot, each robot transferring the sample to at least one test unit;
(e1) particle size,
(e2) elemental distribution, and (e3) water content,
(e4) Crystallographic properties in XRD, or (e5) Specific surface area (BET),
(e6) A method for producing a precursor of an electrode active material, the method comprising: measuring at least one parameter selected from sulfate content. The method according to claim 1, wherein the precursor is selected from a complex oxide, a complex (oxy)hydroxide, and a complex carbonate containing at least one metal selected from cobalt and manganese. 3. The method according to claim 1 or 2, wherein the robot performs step (e) on a plurality of samples in parallel. 4. A method according to any one of claims 1 to 3, wherein in step (e), samples are taken at intervals of 1 to 24 hours. 5. The method according to any one of claims 1 to 4, wherein in step (e1), the particle size distribution is determined. The method according to any one of claims 1 to 5, wherein in step (e2) the elemental distribution is determined by X-ray fluorescence, atomic emission spectroscopy, atomic absorption spectroscopy, or scanning electron microscopy and EDS. . 7. A method according to any one of claims 1 to 6, wherein in step (e3) the water content is determined by Karl Fischer titration in an automatic titrator. 8. According to any one of claims 1 to 7, the entire description of steps (d) to (e) is carried out in a processing device, and the results of the test(s) are compared with a target value by the processing device. the method of. the processing device collects data as input via an input channel and provides an electronic signal to a production control function via an output channel if at least two consecutive samples indicate a negative deviation from a target value; The method according to claim 8. The processing device compares the data of the sample showing a negative deviation from the target value for at least one measured value (e1) to (e6) with the stored data combined with the process parameter of step (a), and thus Method according to claim 8 or 9, characterized in that the data of the measured value(s) (e1) to (e6) are related to at least one of the following: pH value, nickel and other metal content, and stirring speed. A synthesis robot equipped with a device for taking samples of 10 mg to 10 g of nickel-containing oxides, (oxy)hydroxides, hydroxides or carbonates, and of another robot or the same robot serving said samples as a test unit. Transfer to another part
(e1) particle size,
(e2) elemental distribution, and (e3) water content,
(e4) Crystallographic properties in XRD, or (e5) Specific surface area (BET),
(e6) an apparatus set-up comprising means for making measurements regarding at least one parameter selected from: (e6) sulphate content; Claim 11 further comprising a processing device for collecting the data of any of steps (e1) to (e6) as input via an input channel and for comparing the results of the electrochemical test with a target value stored in the processing device. Setup as described in. Collecting data as an input through an input channel and sending an electronic signal to a production control function through an output channel when at least two consecutive samples show a significant deviation from the target value stored in the processing device. 13. A setup according to claim 11 or 12, further comprising a processing device for providing. The processing device combines the measured values (e1) to (e6) with the process parameters of step (a) based on the stored data, and thus combines the measured values (e1) to (e6) with the process parameters of step (a). 14. The setup according to any one of claims 11 to 13, further comprising a model relating the data of ) to the pH value, the content of nickel and other metals, and the stirring speed. 15. The setup of claim 14, wherein the processing device is capable of adapting process parameters based on a comparison with a model and operating conditions when an out-of-spec sample is taken.