JP2021155264A - Manufacturing method of nickel-containing hydroxide - Google Patents

Abstract

To provide a method of manufacturing nickel-containing hydroxide which cannot only improve a packing density but also can produce particles prevented from cracking.SOLUTION: A manufacturing method of nickel-containing hydroxide comprises: a reaction step of obtaining nickel-containing hydroxide by continuously supplying a metal-containing aqueous solution containing nickel, an aqueous solution containing a complexing agent, and an alkaline aqueous solution into a reaction vessel to cause a crystallization reaction; a slurry extracting step for continuously extracting a slurry containing the nickel-containing hydroxide from the reaction vessel; a classification step of continuously supplying the slurry containing the nickel-containing hydroxide to a classifier to classify into a first particle part and a second particle part having smaller average particle size than the first particle part; and a second particle reflux step of continuously returning the second particle part to the reaction vessel, in which the slurry concentration containing the nickel-containing hydroxide in the reaction vessel is adjusted to a range of 50 g/L or larger to 280 g/L or smaller.SELECTED DRAWING: Figure 1

Description

The present invention is a method for producing a nickel-containing hydroxide, and in particular, when a nickel-containing hydroxide is used as a precursor of a positive electrode active material of a secondary battery, particle cracking of the positive electrode active material can be prevented and a positive electrode can be prevented. The present invention relates to a method for producing a nickel-containing hydroxide capable of mounting an active material at a high density.

In recent years, from the viewpoint of reducing the environmental load, secondary batteries have been used in a wide range of fields such as portable devices and vehicles that use or use electricity as a power source. Examples of the secondary battery include a secondary battery using a non-aqueous electrolyte such as a lithium ion secondary battery. A secondary battery using a non-aqueous electrolyte such as a lithium ion secondary battery is suitable for miniaturization and weight reduction, and has excellent characteristics such as high cycle characteristics and high discharge rate characteristics.

Further, in order to further improve the cycle characteristics and the discharge rate characteristics, it is required to improve the packing density of the positive electrode active material mounted on the positive electrode. Therefore, a raw material mixing step of mixing a lithium raw material, a manganese raw material, a magnesium raw material, an aluminum raw material, and a raw material containing a boron compound, and a wet pulverization of the mixed raw materials and then granulation with a spray dryer are performed at 760 ° C to 870 ° C. A step of firing in 0.5 to 30 hours, a step of crushing after firing and classifying into a range of an average particle size of 1 μm to 75 μm, and a magnetic force sorting step of bringing the obtained powder into contact with a magnet to remove magnetic deposits. A method for producing a positive electrode active material for a lithium battery including the above has been proposed (Patent Document 1).

In Patent Document 1, the sintering of fine particles as a raw material is promoted to become a dense positive electrode active material, thereby improving the packing density when the positive electrode active material is mounted on the positive electrode. However, Patent Document 1 has a problem that the manufacturing process is complicated, such as pulverization of raw materials, granulation, pulverization after firing, and classification.

On the other hand, in order to obtain high cycle characteristics and high discharge rate characteristics, it is necessary not only to improve the packing density of the positive electrode active material but also to prevent particle cracking of the positive electrode active material. In Patent Document 1 in which a positive electrode active material is produced by granulating a crushed raw material, there is room for improvement in preventing particle cracking of the positive electrode active material.

Japanese Unexamined Patent Publication No. 2011-082188

In view of the above circumstances, it is an object of the present invention to provide a method for easily producing a nickel-containing hydroxide in which particle cracking is prevented, as well as being able to improve the packing density. By using a nickel-containing hydroxide having improved packing density and prevented particle cracking as a precursor of the positive electrode active material, a positive electrode active material having improved packing density and prevented particle cracking can be obtained. ..

In the present invention, the nickel-containing hydroxide taken out from the reaction vessel where the crystallization reaction is carried out is classified into a first particle portion used as a product and a second particle portion having an average particle diameter smaller than that of the first particle portion. The classified second particle portion is returned to the reaction tank and the concentration of the slurry containing nickel-containing hydroxide in the reaction tank is adjusted within a predetermined range. By adjusting the concentration of the slurry containing nickel-containing hydroxide in the reaction vessel within a predetermined range, nickel-containing hydroxide having improved packing density and prevention of particle cracking can be produced.

The gist of the structure of the present invention is as follows.
[1] A reaction step of continuously supplying a metal-containing aqueous solution containing nickel, an aqueous solution containing a complexing agent, and an alkaline aqueous solution to a reaction vessel for a crystallization reaction to obtain a nickel-containing hydroxide.
A slurry extraction step of continuously extracting a slurry containing the nickel-containing hydroxide from the reaction vessel, and a slurry extraction step.
A classification step of continuously supplying the slurry containing the nickel-containing hydroxide to the classification device and classifying the slurry into a first particle portion and a second particle portion having an average particle diameter smaller than that of the first particle portion.
Including a second particle part reflux step of continuously returning the second particle part to the reaction vessel.
A method for producing a nickel-containing hydroxide, wherein the concentration of the slurry containing the nickel-containing hydroxide in the reaction vessel is adjusted to a range of 50 g / L or more and 280 g / L or less.
[2] The above with respect to the total of the mass (solid content) of the nickel-containing hydroxide constituting the first particle portion and the mass (solid content) of the nickel-containing hydroxide constituting the second particle portion in the classification step. The production method according to [1], wherein the ratio A of the mass (solid content) of the nickel-containing hydroxide constituting the first particle portion is 0.10 or more and 0.33 or less.
[3] and the ratio A, the flow rate B of the slurry containing the nickel-containing hydroxide supplied to the classifier and (L / min), the volume C (m ³⁾ of the reaction vessel, the following expressions 0. 70 ≦ (A × B) / C ≦ 3.50
The manufacturing method according to [2], which satisfies the relationship of.
[4] The manufacturing method according to any one of [1] to [3], wherein the classifying device is a wet classifying device using centrifugal force.
[5] The nickel-containing _{hydroxide, Ni 1-x-y Co} x M y O z (OH) 2-α (0 ≦ x ≦ 0.45,0 ≦ y ≦ 0.45,0 ≦ z ≦ 3.00, −0.50 ≦ α <2.00, M indicates one or more additive metal elements selected from the group consisting of Zr, Al, Ti, Mn, Ga, In and W). The production method according to any one of [1] to [4], which is a represented compound.
[6] The production method according to any one of [1] to [5], wherein the nickel-containing hydroxide is a precursor of a positive electrode active material of a secondary battery.

The above aspect [1] is a method for continuously producing a nickel-containing hydroxide. Further, among the nickel-containing hydroxides taken out from the reaction tank, the first particle part having a large particle size is used as a product, and the second particle part having a small particle size is not used as a product and reacts. It is returned to the tank and used for the crystallization reaction.

Since A × B in the above aspect [3] indicates the degree of production of the first particle portion, (A × B) / C is the amount of the first particle portion produced per unit volume of the reaction vessel. It is an index to show.

According to the aspect of the present invention, the slurry containing the nickel-containing hydroxide is classified into a first particle portion and a second particle portion having an average particle diameter smaller than that of the first particle portion, and the second particle portion is used as a reaction vessel. By adjusting the concentration of the slurry containing nickel-containing hydroxide in the reaction tank while returning it to 50 g / L or more and 280 g / L or less, not only the packing density can be improved, but also the nickel-containing water in which particle cracking is prevented is prevented. Oxides can be produced. Further, according to the aspect of the present invention, the slurry concentration containing nickel-containing hydroxide in the reaction tank may be adjusted to 50 g / L or more and 280 g / L or less while returning the second particle portion to the reaction tank. Is simple.

According to the aspect of the present invention, the ratio of the mass of the nickel-containing hydroxide in the first particle portion to the total mass of the nickel-containing hydroxide in the first particle portion and the mass of the nickel-containing hydroxide in the second particle portion. When A is 0.10 or more and 0.33 or less, the concentration of the slurry containing nickel-containing hydroxide in the reaction tank can be easily adjusted to 50 g / L or more and 280 g / L or less, so that the packing density is improved. It is possible to reliably produce a nickel-containing hydroxide in which particle cracking is also prevented.

According to the aspect of the present invention, the ratio A, the flow rate B (L / min) of the slurry containing the nickel-containing hydroxide supplied to the classifier, and the volume C (m ³ ) of the reaction tank are 0. By satisfying the relationship of 70 ≦ (A × B) / C ≦ 3.50, the concentration of the slurry containing nickel-containing hydroxide in the reaction vessel can be easily adjusted to 50 g / L or more and 280 g / L or less, so that the packing density can be adjusted. It is possible to reliably produce a nickel-containing hydroxide in which the amount of oxides is improved and particle cracking is prevented.

According to the aspect of the present invention, since the classification device is a wet classifying device using centrifugal force, the particle shape of the nickel-containing hydroxide is deformed in the slurry containing the nickel-containing hydroxide taken out from the reaction tank. It is possible to smoothly classify into the first particle part and the second particle part while preventing this.

It is a flow figure explaining the outline of the manufacturing method of this invention. It is explanatory drawing which illustrated the classification apparatus used in the manufacturing method of this invention. It is a scanning microscope (SEM) photograph of the nickel-containing hydroxide obtained in Example and Comparative Example.

The method for producing the nickel-containing hydroxide of the present invention will be described below. Note that FIG. 1 is a flow chart illustrating an outline of the manufacturing method of the present invention. As shown in FIG. 1, in the method for producing a nickel-containing hydroxide of the present invention, a metal-containing aqueous solution containing nickel, an aqueous solution containing a complexing agent, and an alkaline aqueous solution are continuously supplied to a reaction vessel. A reaction step of performing a neutralization crystallization reaction to obtain a nickel-containing hydroxide, a slurry extraction step of continuously extracting a slurry containing a nickel-containing hydroxide from a reaction vessel, and a slurry containing the nickel-containing hydroxide. A reaction between a classification step of continuously supplying to a classification device and classifying into a first particle portion and a second particle portion having an average particle diameter smaller than that of the first particle portion and a second particle portion obtained in the classification step. It includes a second particle part reflux step of continuously returning to the tank. The nickel-containing hydroxide constituting the first particle portion is a nickel-containing hydroxide which is the object of the production method of the present invention.

(Reaction process)
The reaction process for obtaining a nickel-containing hydroxide will be described. As shown in FIG. 1, in the reaction step for obtaining a nickel-containing hydroxide, first, a metal-containing aqueous solution containing nickel, for example, a nickel salt (for example, a sulfate) and, if necessary, a cobalt salt (cobalt salt) are first subjected to a co-precipitation method. For example, an aqueous solution containing a salt (sulfate) and a salt of the added metal (M) (for example, a sulfate), an aqueous solution containing a complexing agent, and an alkaline aqueous solution as a pH adjuster are appropriately added to the reaction vessel. By conducting a neutralization crystallization reaction in the reaction vessel, particles of the nickel-containing hydroxide are grown to prepare a nickel-containing hydroxide. The particle shape of the nickel-containing hydroxide may be, for example, substantially spherical. In the reaction vessel, the nickel-containing hydroxide is in the form of a slurry using water as a dispersion medium.

The complexing agent is particularly limited as long as it can form a complex with an ion of a metal element containing nickel, for example, a nickel ion, a cobalt ion if necessary, and an ion of an additive metal (M) in an aqueous solution. However, for example, an ammonium ion feeder can be mentioned. Examples of the ammonium ion feeder include aqueous ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, ammonium fluoride and the like. Further, in the neutralization crystallization reaction, in order to adjust the pH value of the aqueous solution in the reaction vessel, an alkaline aqueous solution such as an alkali metal hydroxide (for example, sodium hydroxide or potassium hydroxide) is appropriately used as a pH adjuster. , Add to the reaction vessel.

When a metal-containing aqueous solution containing nickel, an aqueous solution containing a complexing agent, and an alkaline aqueous solution are appropriately and continuously supplied to the reaction vessel, and the substances in the reaction vessel are appropriately stirred, the metal in the metal-containing aqueous solution containing nickel is formed. A nickel-containing hydroxide is produced by co-precipitation by the neutralization crystallization reaction. In the neutralization crystallization reaction, the temperature of the reaction vessel is controlled, for example, in the range of 10 ° C. or higher and 90 ° C. or lower, preferably 20 ° C. or higher and 80 ° C. or lower. When an aqueous solution containing a complexing agent and an alkaline aqueous solution are supplied to a reaction vessel to cause a neutralization crystallization reaction, the concentration of the complexing agent in the mixed solution in the reaction vessel is, for example, 1.0 g / L or more and 8.0 g. / L or less, preferably 2.0 g / L or more and 7.0 g / L or less, particularly preferably 3.0 g / L or more and 6.0 g / L or less, and the pH of the mixed solution based on the liquid temperature of 40 ° C. Is controlled, for example, 9.0 or more and 13.0 or less, preferably 10.0 or more and 12.0 or less.

Further, the stirring conditions of the stirring device installed in the reaction tank and the average residence time in the reaction tank may be appropriately adjusted within a predetermined range. By adjusting the stirring conditions of the stirring device and the residence time in the reaction vessel, it is possible to control physical properties such as the specific surface area and particle shape of the nickel-containing hydroxide. For example, the average residence time is preferably 3 hours or more and 12 hours or less, and the stirring speed is preferably 300 rpm or more and 2000 rpm or less, although it depends on the volume of the reaction vessel.

Examples of the reaction tank include a continuous equation for overflowing. The volume of the reaction vessel is not particularly limited, and examples thereof include 0.1 m ^{3 and} more and 30 m ³ or less.

The composition of nickel-containing hydroxide, for _{example, Ni 1-x-y Co} x M y O z (OH) 2-α (0 ≦ x ≦ 0.45,0 ≦ y ≦ 0.45,0 ≦ z ≤3.00, -0.50≤α <2.00, M indicates an additive metal). The additive metal (M) as an optional component consists of a group consisting of zirconium (Zr), aluminum (Al), titanium (Ti), manganese (Mn), gallium (Ga), indium (In) and tungsten (W). Included is one or more selected metal elements. Nickel (Ni) is an essential component, but cobalt (Co) is also an optional component.

(Slurry extraction process)
The slurry containing the nickel-containing hydroxide is withdrawn from the reaction vessel. The slurry containing the nickel-containing hydroxide extracted from the reaction tank is stored in the storage tank and supplied to the classifier. The slurry containing the nickel-containing hydroxide is supplied to the classifier at a flow rate B.

(Classification process)
As shown in FIG. 1, the slurry containing the nickel-containing hydroxide is continuously extracted from the reaction tank and stored in the slurry storage tank, and the first particle portion and the first particle portion, which are large particle size portions, are stored by the classification device. It is classified into a second particle part, which is a small particle size part having an average particle size smaller than that of the particle part. The nickel-containing hydroxide constituting the first particle portion is a nickel-containing hydroxide that has reached a predetermined particle size, and is a nickel-containing hydroxide that is the object of the production method of the present invention. Finally, the first particle portion is carried out as a product from the classification device to the outside of the system of the manufacturing method of the present invention.

On the other hand, the nickel-containing hydroxide constituting the second particle portion is a nickel-containing hydroxide that has not reached a predetermined particle size and is not the object of the production method of the present invention. As will be described later, the second particle portion is not carried out of the system of the manufacturing method of the present invention as a product from the classification device, but is continuously returned to the reaction vessel again.

Examples of the classifying device include a wet classifying device using centrifugal force.

As a wet classifying device, as shown in FIG. 2, a liquid cyclone type classifying device can be mentioned. When a slurry containing nickel-containing hydroxide is supplied (press-fitted) to a liquid cyclone type classifier, particles having a large specific gravity and particle diameter among the nickel-containing hydroxide particles due to the action of centrifugal force generated in the classifier. The particles move toward the peripheral wall of the liquid cyclone type classifier, and the smaller the specific gravity and the particle size, the more the particles move toward the center of the liquid cyclone type classifier. The peripheral wall portion of the liquid cyclone type classifier is formed with a taper that becomes narrower toward the lower side in the direction of gravity. In the peripheral wall portion of the liquid cyclone type classifier, a flow downward in the direction of gravity is generated along this paper. On the other hand, a flow upward in the direction of gravity is generated in the central portion of the liquid cyclone type classifier. From the above, nickel-containing hydroxide particles having a large specific gravity and particle size (that is, the first particle portion) flow downward in the direction of gravity along the peripheral wall portion of the cyclone type classifier and are formed downward in the direction of gravity. It is discharged from the lower discharge port. On the other hand, the nickel-containing hydroxide particles having a small specific gravity and particle diameter (that is, the second particle portion) flow upward in the gravity direction through the central portion of the cyclone type classifier, and are formed on the upper side in the gravity direction. It is discharged from the discharge port.

The liquid cyclone type classifier continuously converts the nickel-containing hydroxide-containing slurry extracted from the reaction vessel into a slurry containing the first particle part and a slurry containing the second particle part by the action of centrifugal force. Classify.

(Second particle part reflux step)
As shown in FIG. 1, the slurry containing the second particle portion classified by the classification device is continuously returned to the reaction tank by the reflux device. The second particle portion returned to the reaction tank is supplied from the reaction tank to the classifier after the particles have grown again by the neutralization crystallization reaction in the reaction tank. When the nickel-containing hydroxide particles supplied to the classifier reach a predetermined particle size, the nickel-containing hydroxide (that is, the first particle portion), which is the object of the production method of the present invention, is obtained from the classifier. It is carried out of the system of the manufacturing method of the present invention. By repeating the above operation, the first particle part generated and grown in the reaction tank is selectively carried out of the reaction tank, and the second particle part reaches the target particle size and becomes the first particle part. Repeat particle growth in the reaction vessel until.

In the production method of the present invention, the slurry concentration containing nickel-containing hydroxide is adjusted to a range of 50 g / L or more and 280 g / L or less in the reaction vessel in which the second particle part is returned in the second particle part reflux step. Has been done. The "slurry concentration containing nickel-containing hydroxide in the reaction vessel" is newly defined in the reaction vessel with the nickel-containing hydroxide in the second particle portion returned to the reaction vessel in the second particle portion refluxing step. It means the total concentration of the nickel-containing hydroxide particles produced in. By adjusting the concentration of the slurry containing nickel-containing hydroxide in the reaction vessel to the range of 50 g / L or more and 280 g / L or less, not only the packing density can be improved, but also the nickel content in which particle cracking is prevented is prevented. Hydroxides can be produced. That is, the nickel-containing hydroxide constituting the first particle portion obtained by the production method of the present invention is prevented from cracking particles, and a high packing density can be obtained. Further, in the production method of the present invention, the concentration of the slurry containing nickel-containing hydroxide in the reaction vessel may be adjusted to 50 g / L or more and 280 g / L or less while returning the second particle portion to the reaction vessel. The manufacturing process is simple because there is no need to provide.

The concentration of the slurry containing nickel-containing hydroxide in the reaction vessel is not particularly limited as long as it is 50 g / L or more and 280 g / L or less, but the lower limit is 70 g / L from the viewpoint of more reliably improving the packing density. It is preferable, and 90 g / L is particularly preferable. On the other hand, the upper limit of the concentration of the slurry containing nickel-containing hydroxide in the reaction vessel is preferably 250 g / L and particularly preferably 220 g / L from the viewpoint of more reliably preventing particle cracking. The above upper limit value and lower limit value can be arbitrarily combined.

From the above, the production method of the present invention may further include a concentration adjusting step of adjusting the slurry concentration of the second particle portion, if necessary. That is, if necessary, as shown in FIG. 1, the second particle part reflux step further includes a concentration step of concentrating the slurry of the second particle part before continuously returning the second particle part to the reaction vessel. It may be. By further including the concentration step of concentrating the slurry of the second particle part, even if the content of the nickel-containing hydroxide constituting the second particle part is reduced, that is, the slurry concentration of the second particle part is lowered. However, since the slurry concentration of the second particle portion can be increased to a desired value by the concentration step, the slurry concentration containing nickel-containing hydroxide in the reaction vessel is surely adjusted to 50 g / L or more and 280 g / L or less. can do. Further, if necessary, although not shown, instead of the concentration step of concentrating the slurry of the second particle part, the second particle part recirculation step is performed before the second particle part is continuously returned to the reaction vessel. A dilution step of diluting the slurry of particles may be further included. By further including a dilution step of diluting the slurry of the second particle part, even if the content of the nickel-containing hydroxide constituting the second particle part becomes excessive, that is, the slurry concentration of the second particle part is high. Even so, the slurry concentration of the second particle portion can be reduced to a desired value by the dilution step, so that the slurry concentration containing the nickel-containing hydroxide in the reaction vessel is surely reduced to 50 g / L or more and 280 g / L or less. Can be adjusted.

The concentration step is not only included in the second particle part refluxing step before the second particle part is continuously returned to the reaction vessel, that is, in the second particle part refluxing step, but also if necessary. The concentration step may be further included in the tank or storage tank. Further, the concentration step may be included in the reaction tank or the storage tank instead of being included in the second particle part reflux step.

Further, in the production method of the present invention, in the classification step, the mass (solid) of the nickel-containing hydroxide constituting the first particle part is classified into the slurry containing the first particle part and the slurry containing the second particle part. Minutes) and the ratio of the mass (solid content) of the nickel-containing hydroxide constituting the first particle portion to the total mass (solid content) of the nickel-containing hydroxide constituting the second particle portion A (hereinafter, simply, The “ratio A”) is not particularly limited, but is preferably adjusted to a predetermined range. The ratio A means the yield of the first particle portion converted into dry particles in the production method of the present invention. The lower limit of the ratio A is preferably 0.10 from the viewpoint of reliably preventing particle cracking without impairing the high packing density, and more preferably 0.11 from the viewpoint of further reliably preventing particle cracking. 0.12 is particularly preferable. On the other hand, the upper limit of the ratio A is preferably 0.33 from the viewpoint of reliably preventing particle cracking and reliably improving the packing density, and from the viewpoint of further reliably improving the filling density, 0. 30 is more preferable, and 0.28 is particularly preferable. The above upper limit value and lower limit value can be arbitrarily combined.

By controlling the ratio A to a range of 0.10 or more and 0.33 or less, the mass (solid content) of the nickel-containing hydroxide constituting the first particle portion and the nickel-containing hydroxide constituting the second particle portion The ratio of the mass (solid content) of the nickel-containing hydroxide constituting the second particle portion to the total mass (solid content) of the substance is controlled in the range of 0.67 or more and 0.90 or less. By controlling the amount of the second particle portion returned to the reaction tank within the above ratio range, it becomes easy to adjust the concentration of the slurry containing nickel-containing hydroxide in the reaction tank to 50 g / L or more and 280 g / L or less. can.

Further, in the production method of the present invention, the above ratio A and the flow rate B (unit: L / min) of the slurry containing the nickel-containing hydroxide supplied to the classifier (hereinafter, simply referred to as “flow rate B”). The relationship between the reaction vessel volume C (unit: m ³ ) (hereinafter, may be simply referred to as “volume C”) is not particularly limited, but (ratio A × flow rate B) / volume C. It is preferable to adjust the value of to a predetermined range. Since the ratio A × the flow rate B indicates the degree of production of the first particle part, (ratio A × flow rate B) / volume C is an index indicating the production amount of the first particle part per unit volume of the reaction vessel. Is. That is, (ratio A × flow rate B) / volume C is an index indicating the degree to which the first particle portion of the product is carried out of the reaction tank per unit volume of the reaction tank.

The lower limit of the value of (ratio A × flow rate B) / volume C is preferably 0.70 from the viewpoint of reliably preventing particle cracking without impairing the high packing density, and is a point of further reliably preventing particle cracking. Therefore, 0.85 is more preferable, and 1.00 is particularly preferable. On the other hand, the upper limit of the value of (ratio A × flow rate B) / volume C is preferably 3.50 from the viewpoint of reliably improving the packing density while further reliably preventing particle cracking, and further increasing the filling density. 3.00 is more preferable, and 2.50 is particularly preferable from the viewpoint of surely improving. That is, in the production method of the present invention, it is preferable to satisfy the relationship of 0.70 ≦ (ratio A × flow rate B) / volume C ≦ 3.50. The above upper limit value and lower limit value can be arbitrarily combined.

By adjusting the amount of the first particle part produced per unit volume of the reaction vessel, that is, by adjusting so as to satisfy the relationship of 0.70 ≦ (ratio A × flow rate B) / volume C ≦ 3.50. , The concentration of the slurry containing nickel-containing hydroxide in the reaction vessel can be easily adjusted to 50 g / L or more and 280 g / L or less.

The nickel-containing hydroxide produced by the production method of the present invention is prevented from cracking particles, and a higher bulk density can be obtained. The nickel-containing hydroxide obtained by the production method of the present invention can obtain, for example, a bulk density of 1.40 g / ml or more. Further, the nickel-containing hydroxide obtained by the production method of the present invention can be confirmed from the nickel-containing hydroxide in 10 fields of view when any 10 fields of view are observed at 2000 times using a scanning electron microscope (SEM). The maximum width of the cracks that can be formed is reduced to 200 nm or less.

A particle size having a cumulative volume percentage of 50% by volume of the nickel-containing hydroxide constituting the first particle portion (hereinafter, may be simply referred to as “D50”) is the use of the nickel-containing hydroxide used as a product. It can be appropriately selected depending on the conditions, the composition of the nickel-containing hydroxide, and the like, and is preferably 3 μm or more and 20 μm or less, for example. The lower limit of D50 of the first particle portion is more preferably 5 μm, and particularly preferably 7 μm. The upper limit of D50 of the first particle portion is more preferably 19 μm, and particularly preferably 18 μm. Further, the D50 of the nickel-containing hydroxide constituting the second particle portion can be appropriately selected depending on the production conditions of the nickel-containing hydroxide and the like, and examples thereof include 1 μm and 15 μm or less.

The nickel-containing hydroxide produced by the production method of the present invention can be used as a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. For example, the nickel-containing hydroxide slurry constituting the first particle portion is filtered, washed with an alkaline aqueous solution, and then washed with water to remove impurities contained in the first particle portion, and then the first particle portion. By heat-treating and drying the nickel-containing hydroxide constituting the above, a nickel-containing hydroxide that can be used as a precursor of the positive electrode active material can be obtained.

Next, a method for producing a positive electrode active material for a lithium ion secondary battery using the nickel-containing hydroxide obtained by the production method of the present invention as a precursor will be described. For example, first, a lithium compound is added to a nickel-containing hydroxide to prepare a mixture of the nickel-containing hydroxide and the lithium compound. The lithium compound is not particularly limited as long as it is a compound having lithium, and examples thereof include lithium carbonate and lithium hydroxide.

Next, the positive electrode active material can be produced by calcining the mixture obtained as described above. Examples of the firing conditions include a firing temperature of 700 ° C. or higher and 1000 ° C. or lower, a heating rate of 50 ° C./h or higher and 300 ° C./h or lower, and a firing time of 5 hours or more and 20 hours or less. The atmosphere of firing is not particularly limited, and examples thereof include the atmosphere and oxygen. The firing furnace used for firing is not particularly limited, and examples thereof include a stationary box furnace and a roller Haworth continuous furnace.

Next, examples of the method for producing a nickel-containing hydroxide of the present invention will be described, but the present invention is not limited to these examples as long as the gist of the present invention is not exceeded.

Method 1 for Producing Nickel-Containing Hydroxide of Example 1 An aqueous solution prepared by dissolving nickel sulfate and cobalt sulfate at a predetermined ratio (number of moles of nickel: number of moles of cobalt = 93: 7) and an aqueous solution of ammonium sulfate (ammonium ion feeder). ) And an aqueous sodium hydroxide solution are added ^{dropwise to the reaction vessel (volume C is 0.5 m 3} ), and the pH of the mixed solution in the reaction vessel is 11.23 based on the liquid temperature of 40 ° C., and the ammonia concentration is 5 g / L. While maintaining, the mixture was continuously stirred with a stirrer. The temperature of the mixed solution in the reaction vessel was maintained at 50.0 ° C. The nickel-containing hydroxide particles produced by the neutralization crystallization reaction were overflowed from the overflow pipe of the reaction tank and continuously extracted as a nickel-containing hydroxide slurry.

The extracted nickel-containing hydroxide slurry is press-fitted into a liquid cyclone type classifier (manufactured by Murata Kogyo Co., Ltd., model "T10-1") at a slurry flow rate of 4.0 L / min (flow rate B). At 0.26 (ratio A), the ratio of the mass of the nickel-containing hydroxide in the first particle part to the total mass of the nickel-containing hydroxide in the particle part and the mass of the nickel-containing hydroxide in the second particle part. The particles were continuously classified into a first particle portion having a D50 of 12.7 μm and a second particle portion having a D50 of 10.2 μm. The slurry of the second particle part was continuously returned to the reaction vessel by the reflux path of the second particle part. At this time, the amount of nickel-containing hydroxide newly generated in the reaction tank and the amount of nickel-containing hydroxide newly generated in the reaction tank are continuously returned to the reaction tank so that the slurry concentration (g / L) of the nickel-containing hydroxide in the reaction tank is within a predetermined range. The amount of the second particle part was controlled.

On the other hand, the slurry of the first particle portion was filtered, washed with an alkaline aqueous solution, and solid-liquid separated. Then, the separated solid phase was washed with water, and further subjected to each treatment of dehydration and drying to obtain a sample nickel-containing hydroxide.

Method for Producing Nickel-Containing Hydroxide of Example 2 In the reaction step, the pH of the mixed solution in the reaction vessel was 11.20 based on the liquid temperature of 40 ° C., and in the classification step, the flow rate B was 2.8 L / min and the ratio A. Nickel-containing water as a sample in the same manner as in Example 1 except that it was continuously classified into a first particle part having a D50 of 0.24 and a D50 of 17.2 μm and a second particle part having a D50 of 13.0 μm. An oxide was obtained.

Method for Producing Nickel-Containing Hydroxide of Example 3 In the reaction step, the pH of the mixed solution in the reaction vessel was 10.88 based on the liquid temperature of 40 ° C., and in the classification step, the flow rate B was 4.7 L / min, and the ratio A. Nickel-containing water as a sample in the same manner as in Example 1 except that it was continuously classified into a first particle portion having a D50 of 0.12 and a D50 of 16.0 μm and a second particle portion having a D50 of 12.5 μm. An oxide was obtained.

Method for Producing Nickel-Containing Hydroxide of Comparative Example 1 In the reaction step, the pH of the mixed solution in the reaction vessel was 11.70 based on the liquid temperature of 40 ° C., and in the classification step, the flow rate B was 5.4 L / min and the ratio A. Nickel-containing water as a sample in the same manner as in Example 1 except that the first particle portion having 0.34 and D50 of 9.8 μm and the second particle portion having D50 of 7.4 μm were continuously classified. An oxide was obtained.

Method for Producing Nickel-Containing Hydroxide of Comparative Example 2 In the reaction step, the pH of the mixed solution in the reaction vessel was 11.55 based on the liquid temperature of 40 ° C., and in the classification step, the flow rate B was 3.7 L / min, and the ratio A. Nickel-containing water as a sample in the same manner as in Example 1 except that the first particle portion having 0.09 and D50 of 17.8 μm and the second particle portion having D50 of 15.5 μm were continuously classified. An oxide was obtained.

Composition of nickel-containing hydroxide, slurry concentration (g / L) of nickel-containing hydroxide in the reaction vessel, ratio A, flow rate B (L / L /) of the slurry of nickel-containing hydroxide supplied to the liquid cyclone type classifier. The values of min), the volume C (m ³ ) of the reaction vessel, and (ratio A × flow rate B) / volume C are shown in Table 1 below.

The composition of the nickel-containing hydroxide was analyzed using an ICP emission spectrometer (Optima (registered trademark) 8300 manufactured by PerkinElmer). The concentration of the slurry containing nickel-containing hydroxide in the reaction tank was determined by drying 1 L of the slurry collected from the reaction tank and measuring the weight after drying.

The nickel-containing hydroxide obtained as a sample was evaluated as follows.
(1) Bulk density (BD: unit g / mL)
The nickel-containing hydroxide obtained as a sample was naturally dropped and filled in a container, and the bulk density was measured from the volume of the container and the mass of the sample. Specifically, the sample was dropped and filled in a 20 cm ³ measuring container while passing the sample through a sieve to make the container filled with the sample, and the sample weight at that time was measured and calculated.

(2) Particle cracking Observe any 10 fields of view at 2000 times using a scanning electron microscope (SEM), calculate the maximum width of particle cracking that can be confirmed from the nickel-containing hydroxide in the 10 fields of view, and calculate the following. Evaluated as.
◯: The maximum width of particle cracking of nickel-containing hydroxide particles is 200 nm or less,
X: Maximum width of particle cracking of nickel-containing hydroxide particles exceeds 200 nm

The above evaluation results are shown in Table 2 below, and scanning electron microscope (SEM) photographs of nickel-containing hydroxides obtained in Examples and Comparative Examples are shown in FIG.

From Tables 1 and 2 above, in Examples 1 to 3 in which the slurry concentration containing nickel-containing hydroxide in the reaction vessel was adjusted to the range of 50 g / L or more and 280 g / L or less, the bulk density was 1.51 g / ml or more. Improved to. Further, from Tables 1 and 2 and FIGS. 3 above, in Examples 1 to 3, the occurrence of particle cracking could be prevented. Further, in Examples 1 to 3, the ratio A is adjusted to the range of 0.10 or more and 0.33 or less, and the value of (ratio A × flow rate B) / volume C is adjusted to the range of 0.70 or more and 3.50 or less. It was being adjusted.

On the other hand, in Comparative Example 1 in which the slurry concentration containing nickel-containing hydroxide in the reaction vessel was 40.0 g / L, the occurrence of particle cracking could be prevented from Tables 2 and 3 above, but from Table 2 above. , The bulk density was 1.20 g / mL and the packing density was lowered. Further, in Comparative Example 2 in which the concentration of the slurry containing nickel-containing hydroxide in the reaction vessel was 293.8 g / L, the bulk density was 1.76 g / mL and the packing density was improved from Table 2 above. From 2 and FIG. 3, particle cracking occurred. Further, from Table 1 above, in Comparative Example 1, the ratio A is 0.34, the value of (ratio A × flow rate B) / volume C is 3.64, and in Comparative Example 2, the ratio A is 0.09. The value of (ratio A × flow rate B) / volume C was 0.69.

In the method for producing a nickel-containing hydroxide of the present invention, the packing density can be improved and a nickel-containing hydroxide in which particle cracking is prevented can be easily produced, so that a high cycle characteristic and a high discharge rate can be obtained. It has high utility value in the field of positive electrode active materials for secondary batteries where characteristics are required.

Claims (6)

A reaction step of continuously supplying a metal-containing aqueous solution containing nickel, an aqueous solution containing a complexing agent, and an alkaline aqueous solution to a reaction vessel for a crystallization reaction to obtain a nickel-containing hydroxide.
A slurry extraction step of continuously extracting a slurry containing the nickel-containing hydroxide from the reaction vessel, and a slurry extraction step.
A classification step of continuously supplying the slurry containing the nickel-containing hydroxide to the classification device and classifying the slurry into a first particle portion and a second particle portion having an average particle diameter smaller than that of the first particle portion.
Including a second particle part reflux step of continuously returning the second particle part to the reaction vessel.
A method for producing a nickel-containing hydroxide, wherein the concentration of the slurry containing the nickel-containing hydroxide in the reaction vessel is adjusted to a range of 50 g / L or more and 280 g / L or less. The first particle with respect to the total mass (solid content) of the nickel-containing hydroxide constituting the first particle portion and the mass (solid content) of the nickel-containing hydroxide constituting the second particle portion in the classification step. The production method according to claim 1, wherein the ratio A of the mass (solid content) of the nickel-containing hydroxide constituting the part is 0.10 or more and 0.33 or less. The ratio A, the flow rate B (L / min) of the slurry containing the nickel-containing hydroxide supplied to the classifier, and the volume C (m ³ ) of the reaction tank are expressed by the following formula 0.70 ≦ ( A × B) / C ≦ 3.50
The manufacturing method according to claim 2, wherein the relationship is satisfied. The manufacturing method according to any one of claims 1 to 3, wherein the classifying device is a wet classifying device using centrifugal force. Said nickel-containing _{hydroxide, Ni 1-x-y Co} x M y O z (OH) 2-α (0 ≦ x ≦ 0.45,0 ≦ y ≦ 0.45,0 ≦ z ≦ 3.00 , −0.50 ≦ α <2.00, M represents one or more additive metal elements selected from the group consisting of Zr, Al, Ti, Mn, Ga, In and W). The production method according to any one of claims 1 to 4, which is a compound. The production method according to any one of claims 1 to 5, wherein the nickel-containing hydroxide is a precursor of a positive electrode active material of a secondary battery.

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