KR20220158684A - Method for producing nickel-containing hydroxide - Google Patents

Abstract

The present invention provides a simple and easy method for producing a nickel-containing hydroxide capable of improving packing density and preventing particle cracking.
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 tank to crystallize them to obtain a nickel-containing hydroxide, and a slurry containing the nickel-containing hydroxide from the reaction tank A slurry extraction step of continuously extracting, and a classification step of continuously supplying the slurry containing the nickel-containing hydroxide to a classifier and classifying it into a first particle portion and a second particle portion having a smaller average particle diameter than the first particle portion; , A second particle portion reflux step of continuously returning the second particle portion to the reaction tank, and adjusting the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank to a range of 50 g / L or more and 280 g / L or less, Method for producing nickel-containing hydroxide.

Description

Method for producing nickel-containing hydroxide

The present invention is a method for producing a nickel-containing hydroxide, in particular, when the nickel-containing hydroxide is used as a precursor for a secondary battery cathode active material, nickel that can prevent particle cracking of the cathode active material and mount the cathode active material at a high density. It relates to a method for producing the containing hydroxide.

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 secondary batteries include secondary batteries using non-aqueous electrolytes such as lithium ion secondary batteries. Secondary batteries using non-aqueous electrolytes such as lithium ion secondary batteries are suitable for miniaturization and weight reduction, and have excellent characteristics such as high cycle characteristics and high discharge rate characteristics.

In addition, in order to further improve cycle characteristics and discharge rate characteristics, improvement in the charge density of the positive electrode active material mounted on the positive electrode is required. 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 after wet grinding the mixed raw materials, granulating with a spray dryer, A step of firing at 870 ° C. for 0.5 to 30 hours, a step of pulverizing after firing and classifying into an average particle diameter of 1 μm to 75 μm, and a magnetic separation step of removing magnetism by contacting the obtained powder with a magnet. A method for producing a cathode active material for a lithium battery has been proposed (Patent Document 1).

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

Meanwhile, 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 pulverized raw materials, there is room for improvement in preventing particle cracking of the positive electrode active material.

[Prior art literature]

[Patent Literature]

[Patent Document 1] Japanese Unexamined Patent Publication No. 2011-082188

In view of the above circumstances, an object of the present invention is to provide a method for simply and easily producing a nickel-containing hydroxide capable of improving packing density and preventing particle cracking. A positive electrode active material having an improved packing density and preventing particle cracking can be obtained by using a nickel-containing hydroxide having an improved packing density and preventing particle cracking as a precursor of the positive electrode active material.

In the present invention, the nickel-containing hydroxide taken out of the reaction tank in which the crystallization reaction is performed is classified into a first particle portion used as a product and a second particle portion having a smaller average particle diameter than the first particle portion. The classified second particle portion is returned to the reaction tank, and the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank is adjusted to a predetermined range. By adjusting the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank to a predetermined range, the packing density is improved and the nickel-containing hydroxide in which particle cracking is prevented is produced.

The gist of the configuration of the present invention is as follows.

[1] A reaction step of obtaining a 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 to a reaction tank for a crystallization reaction;

A slurry extraction step of continuously extracting the slurry containing the nickel-containing hydroxide from the reaction tank;

A classification step of continuously supplying the slurry containing the nickel-containing hydroxide to a classifier and classifying it into a first particle portion and a second particle portion having a smaller average particle diameter than the first particle portion;

A second particle portion reflux step of continuously returning the second particle portion to the reaction tank;

A method for producing a nickel-containing hydroxide, wherein the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank is adjusted to a range of 50 g / L or more and 280 g / L or less.

[2] Constituting the first particle portion relative to the sum of the weight (solid content) of the nickel-containing hydroxide constituting the first particle portion and the weight (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 weight (solid content) of the nickel-containing hydroxide is 0.10 or more and 0.33 or less.

[3] 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 described in [2] that satisfies the relationship of

[4] The manufacturing method according to any one of [1] to [3], wherein the classifier is a wet classifier using centrifugal force.

[5] The nickel-containing hydroxide is Ni _1-xy 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 [1] to [4], which is a compound represented by.

[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 for a secondary battery.

In the embodiment of the above [1], it is a method for continuously producing a nickel-containing hydroxide. In addition, among the nickel-containing hydroxides taken out of the reaction tank, the first particle portion having a large particle size is used as a product, and the second particle portion having a small particle size portion is returned to the reaction tank without being used as a product and is used for crystallization reaction.

Since A × B in the above embodiment [3] represents the degree of production of the first particle portion, (A × B)/C is an index showing the amount of the first particle portion produced per unit volume of the reaction tank. to be.

According to an aspect of the present invention, the slurry containing nickel-containing hydroxide is classified into a first particle portion and a second particle portion having a smaller average particle diameter than the first particle portion, and the nickel-containing reaction tank is returned while returning the second particle portion to the reaction tank. By adjusting the concentration of the slurry containing the hydroxide 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 hydroxide in which particle cracking is prevented can be produced. Further, according to the aspect of the present invention, the concentration of the slurry containing the 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, so the manufacturing process is simple and easy.

According to an aspect of the present invention, the ratio A of the weight of the nickel-containing hydroxide of the first particle portion to the sum of the weight of the nickel-containing hydroxide of the first particle portion and the weight of the nickel-containing hydroxide of the second particle portion is 0.10 or more and 0.33 or less, Since 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, nickel-containing hydroxide with improved packing density and particle cracking can be prevented reliably.

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 0.70 ≤ (A × B) By satisfying the relationship /C ≤ 3.50, 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 nickel-containing hydroxide with improved packing density and particle cracking is prevented. can be manufactured with certainty.

According to the aspect of the present invention, since the classifier is a wet classifier using centrifugal force, the slurry containing the nickel-containing hydroxide taken out of the reaction tank is smoothly separated from the first particle portion while preventing the particle shape of the nickel-containing hydroxide from being deformed. It can be classified into two particle parts.

1 is a flow chart explaining the outline of the manufacturing method of the present invention.
2 is an explanatory diagram illustrating a classifier used in the production method of the present invention.
3 is a scanning electron microscope (SEM) photograph of nickel-containing hydroxides obtained in Examples and Comparative Examples.

Hereinafter, the method for producing the nickel-containing hydroxide of the present invention will be described. 1 is a flow chart explaining the 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 tank to cause a neutralization crystallization reaction, A reaction step of obtaining a hydroxide-containing compound, a slurry extraction step of continuously extracting a slurry containing a nickel-containing hydroxide from a reaction tank, and continuously supplying the slurry containing the nickel-containing hydroxide to a classifying device, A classification step of classifying into a second particle portion having a smaller average particle diameter than the first particle portion, and a second particle portion reflux step of continuously returning the second particle portion obtained in the classification step to the reaction tank. The nickel-containing hydroxide constituting the first particle portion is the nickel-containing hydroxide that is the object of the production method of the present invention.

(reaction process)

A reaction process for obtaining a nickel-containing hydroxide will be described. As shown in FIG. 1, the reaction step of obtaining a nickel-containing hydroxide is, first, by a co-precipitation method, a metal-containing aqueous solution containing nickel, such as nickel salt (eg, sulfate), and, if necessary, cobalt salt. (e.g., sulfate) and a salt of the added metal (M) (e.g., sulfate), an aqueous solution containing a complexing agent, and an alkaline aqueous solution as a pH adjuster are appropriately added to a reaction tank, By carrying out a neutralization crystallization reaction in a reaction tank, particles of the nickel-containing hydroxide are grown to produce the nickel-containing hydroxide. The particle shape of the nickel-containing hydroxide may be approximately spherical, for example. In the reaction tank, the nickel-containing hydroxide is in the form of a slurry using water as a dispersion medium.

The complexing agent is not particularly limited as long as it can form a complex with an ion of a metal element containing nickel, for example, a nickel ion, if necessary, a cobalt ion, and an ion of an added metal (M) in an aqueous solution, For example, it may be an ammonium ion supplier. The ammonium ion donor may be, for example, aqueous ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, or ammonium fluoride. During the neutralization crystallization reaction, in order to adjust the pH value of the aqueous solution in the reaction tank, an alkaline aqueous solution such as an alkali metal hydroxide (eg, sodium hydroxide or potassium hydroxide) is appropriately added into the reaction tank as a pH adjuster.

When a metal-containing aqueous solution containing nickel, an aqueous solution containing a complexing agent, and an alkaline aqueous solution are suitably continuously supplied to a reaction tank and the materials in the reaction tank are appropriately stirred, the metal in the metal-containing aqueous solution containing nickel is coprecipitated by neutralization crystallization reaction. As a result, nickel-containing hydroxide is produced. In the neutralization crystallization reaction, the temperature of the reaction vessel is controlled within the range of, for example, 10°C or more and 90°C or less, preferably 20°C or more and 80°C or less. When an aqueous solution containing a complexing agent and an alkaline aqueous solution are supplied to a reaction tank to carry out a neutralization crystallization reaction, the concentration of the complexing agent in the mixed solution in the reaction tank 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 based on the liquid temperature of 40 ° C. in the mixture is, for example, 9.0 or more and 13.0 or less, preferably 10.0 Control to more than 12.0 or less.

In addition, 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 tank, physical properties such as the specific surface area and particle shape of the nickel-containing hydroxide can be controlled. 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 varies depending on the volume of the reaction tank.

The reaction vessel may be, for example, a continuous type that overflows. In addition, the volume of the reaction tank is not particularly limited, but may be, for example, 0.1 m 3 or more and 30 m 3 or less.

As the composition of the nickel-containing hydroxide, for example, Ni _1-xy 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 an added metal). As the additive metal (M), which is an optional component, one selected from the group consisting of zirconium (Zr), aluminum (Al), titanium (Ti), manganese (Mn), gallium (Ga), indium (In), and tungsten (W) The above metal elements are exemplified. Also, nickel (Ni) is an essential component, but cobalt (Co) is an optional component.

(Slurry extraction process)

A slurry containing nickel-containing hydroxide is extracted from the reactor. The slurry containing the nickel-containing hydroxide extracted from the reaction tank is stored in a storage tank and supplied to a 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 nickel-containing hydroxide is continuously extracted from the reaction tank and collected in a slurry storage tank, and a first particle portion that is a large particle size portion and a quench having an average particle diameter smaller than the first particle portion are It is classified as the second particle part, which is the neck part. The nickel-containing hydroxide constituting the first particle portion is a nickel-containing hydroxide that has reached a predetermined particle size, and is the target product of the production method of the present invention. The first particle portion is finally taken out of the production method of the present invention from the classifier as a product.

On the other hand, the nickel-containing hydroxide constituting the second particle portion is a nickel-containing hydroxide that does not reach a predetermined particle size and does not become the target product of the production method of the present invention. As will be described later, the second particle portion is continuously returned to the reaction tank again without being taken out of the production method of the present invention as a product from the classifier.

The classifier may be, for example, a wet classifier using centrifugal force.

As a wet classifier, as shown in FIG. 2, a liquid cyclone type classifier is mentioned. When a slurry containing nickel-containing hydroxide is supplied (pressurized injection) to a liquid cyclone-type classifier, by the action of the centrifugal force generated in the classifier, among the particles of the nickel-containing hydroxide, the larger the specific gravity and particle diameter, the liquid It moves in the direction of the outer circumferential wall of the cyclone-type classifier, and the smaller the specific gravity and particle size, the more it moves toward the center of the liquid cyclone-type classifier. On the outer circumferential wall portion of the liquid cyclone-type classifier, a taper narrowing in the downward direction in the gravity direction is formed. At the outer circumferential wall portion of the liquid cyclone classifier, a downward flow in the gravitational direction is generated along the taper. On the other hand, a flow upward in the gravitational direction is generated in the central portion of the liquid cyclone classifier. From the above, the particles of the nickel-containing hydroxide having a large specific gravity and particle diameter (i.e., the first particle portion) flow downward in the gravity direction along the outer circumferential wall of the cyclonic classifier and are discharged from the lower discharge port formed downward in the gravity direction. . On the other hand, particles of nickel-containing hydroxide having a small specific gravity and particle diameter (i.e., the second particle portion) flow upward in the gravitational direction at the center of the cyclone type classifier, and are discharged from the upper discharge port formed above in the gravitational direction.

The liquid cyclone classifier continuously classifies the slurry containing the nickel-containing hydroxide extracted from the reaction tank into a slurry containing a first particle portion and a slurry containing a second particle portion by the action of centrifugal force.

(Second Particle Reflux Process)

As shown in FIG. 1, the slurry containing the 2nd particle part classified by the classifier is continuously returned to the reaction tank by the reflux device. The second particle portion returned to the reaction tank is further grown in the reaction tank by neutralization and crystallization reaction, and then supplied from the reaction tank to the classifier. When the particles of the nickel-containing hydroxide supplied to the classifier reach a predetermined particle size, the nickel-containing hydroxide (i.e., the first particle portion), which is the object of the production method of the present invention, is carried out from the classifier to the outside of the production method of the present invention. do. By repeating the above operation, while the first particle portion generated and grown in the reaction tank is selectively taken out of the reaction tank, the particle growth in the reaction tank is repeated until the second particle portion reaches the target particle size and becomes the first particle portion.

In the production method of the present invention, in the reaction tank in which the second particle portion is returned in the second particle portion reflux step, the concentration of the slurry containing the nickel-containing hydroxide is adjusted to a range of 50 g/L or more and 280 g/L or less. In addition, the "slurry concentration containing nickel-containing hydroxide in the reaction tank" is the sum of the nickel-containing hydroxide of the second particle portion returned to the reaction tank in the second particle portion reflux step and the particles of the nickel-containing hydroxide newly generated in the reaction tank. means concentration. Since the concentration of the slurry containing nickel-containing hydroxide in the reaction tank is adjusted within 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-containing hydroxide in which particle cracking is prevented is produced can do. That is, the nickel-containing hydroxide constituting the first particle portion obtained by the production method of the present invention is prevented from particle cracking, and a high packing density can be obtained. In addition, in the production method of the present invention, the concentration of the slurry containing nickel-containing hydroxide in the reaction tank can be adjusted to 50 g/L or more and 280 g/L or less while returning the second particle portion to the reaction tank, so there is no need to provide additional equipment, The manufacturing process is simple and easy.

The concentration of the slurry containing nickel-containing hydroxide in the reaction tank 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 preferably 70 g/L from the viewpoint of more reliably improving the packing density, and 90 g /L is particularly preferred. On the other hand, the upper limit of the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank is preferably 250 g/L, particularly preferably 220 g/L, from the viewpoint of more reliably preventing particle cracking. In addition, the said upper limit and lower limit can be combined arbitrarily.

From the above, the production method of the present invention may further include a concentration adjustment step of adjusting the concentration of the slurry of the second particle portion, if necessary. That is, if necessary, as shown in FIG. 1 , the second particle portion refluxing step may further include a concentration step of concentrating the slurry of the second particle portion before continuously returning the second particle portion to the reaction vessel. By further including a concentration step of concentrating the slurry of the second particle portion, even if the content of the nickel-containing hydroxide constituting the second particle portion is reduced, that is, even if the concentration of the slurry in the second particle portion is reduced, the concentration step results in the second particle Since the concentration of the negative slurry can be raised to a desired value, the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank can be reliably adjusted to 50 g/L or more and 280 g/L or less. Further, if necessary, although not shown, instead of the concentration step of concentrating the slurry of the second particle portion, a dilution step of diluting the slurry of the second particle portion before the second particle portion reflux step continuously returns the second particle portion to the reaction tank. may further include. By further including a dilution step of diluting the slurry of the second particle portion, even if the content of the nickel-containing hydroxide constituting the second particle portion becomes excessive, that is, even if the concentration of the slurry in the second particle portion becomes high, the dilution step results in the second particle portion. Since the concentration of the negative slurry can be reduced to a desired value, the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank can be reliably adjusted to 50 g/L or more and 280 g/L or less.

In addition, the concentration step is not only included in the second particle portion reflux step before continuously returning the second particle portion to the reaction tank in the second particle portion reflux step, that is, included in the second particle portion reflux step, but also the concentration in the reaction tank or storage tank, if necessary. Further steps may be included. In addition, the concentration process may be included in a reaction tank or a storage tank instead of being included in the second particle part reflux process.

Further, in the production method of the present invention, in the classification step, in classifying into a slurry containing the first particle portion and a slurry containing the second particle portion, the weight (solid content) of the nickel-containing hydroxide constituting the first particle portion and the The ratio A of the weight (solid content) of the nickel-containing hydroxide constituting the first particle portion to the total weight (solid content) of the nickel-containing hydroxide constituting the two particle portions (hereinafter, simply referred to as “ratio A”) is not particularly limited. However, it is desirable to adjust it within a predetermined range. The ratio A means the yield of the first particle portion in terms of 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 lowering the high packing density, more preferably 0.11 from the viewpoint of more reliably preventing particle cracking, and particularly preferably 0.12. do. On the other hand, the upper limit of the ratio A is preferably 0.33 from the viewpoint of reliably improving the packing density while preventing particle cracking more reliably, and more preferably 0.30 from the viewpoint of more reliably improving the packing density, and 0.28 is particularly preferred. In addition, the said upper limit and lower limit can be combined arbitrarily.

By controlling the ratio A within the range of 0.10 or more and 0.33 or less, the second particle relative to the sum of the weight (solid content) of the nickel-containing hydroxide constituting the first particle portion and the weight (solid content) of the nickel-containing hydroxide constituting the second particle portion The ratio of the weight (solid content) of the nickel-containing hydroxide constituting the part is controlled within 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 range of the above ratio, the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank can be easily adjusted to 50 g/L or more and 280 g/L or less.

Further, in the production method of the present invention, the 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 volume C (unit: m3) of the reaction tank (hereinafter simply referred to as “volume C”) is not particularly limited, but adjusting the value of (ratio A × flow rate B) / volume C to a predetermined range it is desirable Since the ratio A×the flow rate B indicates the degree of production of the first particle portion, (ratio A×flow rate B)/volume C is an index indicating the amount of production of the first particle portion per unit volume of the reaction tank. That is, (ratio A×flow rate B)/volume C is an index indicating the degree to which the first particle portion, which is the product, per unit volume of the reaction tank is taken out 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 compromising the high packing density, and 0.85 from the viewpoint of more reliably preventing particle cracking. More preferred, 1.00 is particularly preferred. 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 preventing particle cracking more reliably, and from the viewpoint of more reliably improving the packing density 3.00 is more preferable, and 2.50 is especially preferable. That is, in the manufacturing method of the present invention, it is preferable to satisfy the relationship of 0.70 ≤ (ratio A × flow rate B) / volume C ≤ 3.50. In addition, the said upper limit and lower limit can be combined arbitrarily.

By adjusting the amount of the first particle portion produced per unit volume of the reaction tank, that is, adjusting to satisfy the relationship of 0.70 ≤ (ratio A × flow rate B) / volume C ≤ 3.50, the slurry containing nickel-containing hydroxide in the reaction tank The concentration can be easily adjusted to be 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 particle cracking, 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, in the nickel-containing hydroxide obtained by the production method of the present invention, when observing 10 random fields of view at 2000 times using a scanning electron microscope (SEM), the maximum width of particle cracks that can be confirmed from the nickel-containing hydroxide in 10 fields of view is 200 nm or less. was reduced to

The particle diameter at which the cumulative volume percentage of the nickel-containing hydroxide constituting the first particle portion is 50% by volume (hereinafter simply referred to as “D50”) is the usage condition of the nickel-containing hydroxide used as a product, the composition of the nickel-containing hydroxide It can be appropriately selected according to the like, and for example, 3 μm or more and 20 μm or less are preferable. 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, particularly preferably 18 μm. In addition, the D50 of the nickel-containing hydroxide constituting the second particle portion can be appropriately selected depending on the manufacturing conditions of the nickel-containing hydroxide, and may be, for example, 1 μm or more and 15 μm or less.

The nickel-containing hydroxide produced by the production method of the present invention can be used as a precursor for a positive electrode active material of a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. For example, the slurry of the nickel-containing hydroxide 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 nickel constituting the first particle portion. By heat-treating the containing hydroxide and drying it, a nickel-containing hydroxide usable as a precursor of a positive electrode active material can be obtained.

Next, a method for producing a cathode 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, a mixture of a nickel-containing hydroxide and a lithium compound is prepared by first adding a lithium compound to the nickel-containing hydroxide. The lithium compound is not particularly limited as long as it is a compound containing lithium, and examples thereof include lithium carbonate and lithium hydroxide.

Subsequently, a cathode active material may be prepared by sintering the mixture obtained in the above manner. As the firing conditions, for example, a firing temperature of 700°C or more and 1000°C or less, a temperature increase rate of 50°C/h or more and 300°C/h or less, and a firing time of 5 hours or more and 20 hours or less. The firing atmosphere is not particularly limited, but may be, for example, air, oxygen, or the like. Further, the firing furnace used for firing is not particularly limited, but may be, for example, a stationary type box furnace, a roller hearth type continuous furnace, or the like.

[Example]

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

Method for preparing the nickel-containing hydroxide of Example 1

An aqueous solution in which nickel sulfate and cobalt sulfate were dissolved at a predetermined ratio (number of moles of nickel: number of moles of cobalt = 93:7), an aqueous solution of ammonium sulfate (ammonium ion supplying agent), and an aqueous solution of sodium hydroxide were placed in a reaction tank (volume C is 0.5 m 3 ). It was added dropwise, and while maintaining the pH of the mixed solution in the reaction tank at 11.23 and the ammonia concentration at 5 g/L at a liquid temperature of 40°C, the mixture was continuously stirred with a stirrer. In addition, the liquid temperature of the liquid mixture in the reaction vessel was maintained at 50.0°C. Particles of the nickel-containing hydroxide produced by the neutralization crystallization reaction were allowed to overflow from the overflow tube of the reaction tank, and a slurry of the nickel-containing hydroxide was continuously extracted.

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

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

Method for preparing the nickel-containing hydroxide of Example 2

In the reaction step, the pH of the mixed solution in the reaction tank is 11.20 based on the liquid temperature of 40 ° C. In the classification step, the flow rate B is 2.8 L / min, the ratio A is 0.24, and the first particle portion having a D50 of 17.2 μm and the first particle portion having a D50 of 13.0 μm A sample of the nickel-containing hydroxide was obtained in the same manner as in Example 1 except that the mixture was continuously classified into two particle parts.

Method for preparing the nickel-containing hydroxide of Example 3

In the reaction step, the pH of the mixed solution in the reaction tank is 10.88 based on the liquid temperature of 40 ° C. In the classification step, the flow rate B is 4.7 L / min, the ratio A is 0.12, and the first particle portion having a D50 of 16.0 μm and the first particle portion having a D50 of 12.5 μm A sample of the nickel-containing hydroxide was obtained in the same manner as in Example 1 except that the mixture was continuously classified into two particle parts.

Manufacturing method of nickel-containing hydroxide of Comparative Example 1

In the reaction step, the pH of the mixed solution in the reaction tank is 11.70 based on the liquid temperature of 40 ° C. In the classification step, the flow rate B is 5.4 L / min, the ratio A is 0.34, and the first particle portion having a D50 of 9.8 μm and the first particle portion having a D50 of 7.4 μm A sample of the nickel-containing hydroxide was obtained in the same manner as in Example 1 except that the mixture was continuously classified into two particle parts.

Manufacturing method of nickel-containing hydroxide of Comparative Example 2

In the reaction step, the pH of the mixed solution in the reaction tank is 11.55 based on the liquid temperature of 40 ° C. In the classification step, the flow rate B is 3.7 L / min, the ratio A is 0.09, and the first particle portion having a D50 of 17.8 μm and the first particle portion having a D50 of 15.5 μm A sample of the nickel-containing hydroxide was obtained in the same manner as in Example 1 except that the mixture was continuously classified into two particle parts.

The composition of the nickel-containing hydroxide, the concentration of the nickel-containing hydroxide slurry in the reaction tank (g / L), the ratio A, the flow rate of the nickel-containing hydroxide slurry supplied to the liquid cyclone classifier B (L / min), the volume of the reaction tank C ( ㎥), (ratio A×flow rate B)/volume C are shown in Table 1 below.

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

Composition of nickel-containing hydroxide Slurry Concentration of Nickel-containing Hydroxide in Reactor Ratio A Slurry flow rate B Volume C of the reactor (Ratio A×Flow B)/Volume C unit mole ratio g/L - L/min ㎥ - Example 1 Ni:Co = 93:7 91.1 0.26 4.0 0.5 2.10 Example 2 Ni:Co = 93:7 126.8 0.24 2.8 0.5 1.32 Example 3 Ni:Co = 93:7 216.9 0.12 4.7 0.5 1.13 Comparative Example 1 Ni:Co = 93:7 40.0 0.34 5.4 0.5 3.64 Comparative Example 2 Ni:Co = 93:7 293.8 0.09 3.7 0.5 0.69

About the nickel-containing hydroxide obtained as a sample, the following evaluation was performed.

(1) Bulk density (BD: unit g/mL)

The nickel-containing hydroxide obtained as a sample was naturally dropped and filled into a container, and the bulk density was measured from the volume of the container and the weight of the sample. Specifically, a 20 cm 3 measurement container was drop filled while passing a sample through a sieve, and the container was filled with the sample, and the sample weight at that time was measured and calculated.

(2) Particle Cracks

Random 10 fields of view were observed at 2000 times magnification using a scanning electron microscope (SEM), and the maximum width of particle cracks identifiable from the nickel-containing hydroxide was calculated among the 10 fields of view, and evaluated as follows.

○: the maximum width of particle cracks of particles of nickel-containing hydroxide is 200 nm or less,

×: The maximum width of particle cracks of particles of nickel-containing hydroxide exceeds 200 nm

The 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. 3 .

particle crack bulk density unit - g/mL Example 1 ○ 1.51 Example 2 ○ 1.61 Example 3 ○ 1.66 Comparative Example 1 ○ 1.20 Comparative Example 2 × 1.76

As shown in Tables 1 and 2, in Examples 1 to 3 in which the concentration of the slurry containing nickel-containing hydroxide in the reaction tank was adjusted to a range of 50 g/L or more and 280 g/L or less, the bulk density was improved to 1.51 g/mL or more. . In addition, as shown in Tables 1 and 2 and FIG. 3, in Examples 1 to 3, it was possible to prevent particle cracking. In Examples 1 to 3, the ratio A was adjusted within the range of 0.10 or more and 0.33 or less, and the value of (ratio A×flow rate B)/volume C was adjusted within the range of 0.70 or more and 3.50 or less.

On the other hand, in Comparative Example 1 in which the concentration of the slurry containing nickel-containing hydroxide in the reaction tank was 40.0 g/L, from Table 2 and FIG. 3, it was possible to prevent particle cracking, but from Table 2, the bulk density was 1.20 Packing density decreased in g/mL. In addition, in Comparative Example 2 in which the concentration of the slurry containing nickel-containing hydroxide in the reaction tank was 293.8 g / L, as shown in Table 2, the bulk density was improved to 1.76 g / mL, but as shown in Tables 2 and 3 , particle cracking occurred. In addition, as shown in Table 1 above, in Comparative Example 1, ratio A was 0.34, (ratio A×flow rate B)/volume C was 3.64, and in Comparative Example 2, ratio A was 0.09, (ratio A×flow rate B) )/volume C was 0.69.

In the method for producing nickel-containing hydroxide of the present invention, since the nickel-containing hydroxide can be simply and easily prepared with improved charge density and particle cracking, high cycle characteristics and high discharge rate characteristics are required. It has high utility value in the field of active materials.

Claims (6)

a reaction step of obtaining a 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 to a reaction vessel for a crystallization reaction;
a slurry extraction step of continuously extracting the slurry containing the nickel-containing hydroxide from the reactor;
a classification step of continuously supplying the slurry containing the nickel-containing hydroxide to a classifier and classifying it into a first particle portion and a second particle portion having a smaller average particle diameter than the first particle portion;
A second particle portion reflux step of continuously returning the second particle portion to the reaction tank;
Adjusting the concentration of the slurry containing the nickel-containing hydroxide in the reaction tank to a range of 50 g / L or more and 280 g / L or less,
Method for producing nickel-containing hydroxide.
The method of claim 1,
Nickel content constituting the first particle portion relative to the sum of the weight (solid content) of the nickel-containing hydroxide constituting the first particle portion and the weight (solid content) of the nickel-containing hydroxide constituting the second particle portion in the classification step. The manufacturing method in which the ratio A of the weight (solid content) of hydroxide is 0.10 or more and 0.33 or less.
The method of claim 2,
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
A manufacturing method that satisfies the relationship of 0.70 ≤ (A × B) / C ≤ 3.50.
The method according to any one of claims 1 to 3,
The manufacturing method in which the said classifier is a wet classifier using centrifugal force.
The method according to any one of claims 1 to 4,
The nickel-containing hydroxide is Ni _1-xy 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 is represents one or more additive metal elements selected from the group consisting of Zr, Al, Ti, Mn, Ga, In, and W.).
The method according to any one of claims 1 to 5,
The nickel-containing hydroxide is a precursor of a secondary battery positive electrode active material, a manufacturing method.

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