JP7220849B2 - Nickel-containing hydroxide and its production method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a nickel-containing hydroxide as a raw material for a positive electrode active material for non-aqueous electrolyte secondary batteries, and a method for producing the same.

In recent years, with the spread of mobile electronic devices such as mobile phones and notebook personal computers, there is a demand for the development of small and lightweight secondary batteries with high energy density. There is also a demand for the development of high-output secondary batteries as batteries for electric vehicles such as hybrid vehicles. Lithium ion secondary batteries are known as non-aqueous electrolyte secondary batteries that satisfy such requirements. A lithium ion secondary battery is composed of a negative electrode, a positive electrode, an electrolytic solution, and the like, and a material capable of desorbing and intercalating lithium is used as an active material for the negative electrode and the positive electrode.

Lithium-ion secondary batteries using lithium composite oxides, especially lithium-cobalt composite oxides, which are relatively easy to synthesize, as positive electrode materials can obtain a high voltage of the 4V class, so they are expected to have high energy densities. Practical use is progressing. Batteries using lithium-cobalt composite oxides have been extensively developed to obtain excellent initial capacity characteristics and cycle characteristics, and various results have already been obtained.

However, since lithium-cobalt composite oxide uses an expensive cobalt compound as a raw material, the unit price per capacity of a battery using this lithium-cobalt composite oxide is significantly higher than that of a nickel-metal hydride battery, and the applicable applications are quite large. Limited. Therefore, it is possible to reduce the cost of positive electrode materials and manufacture cheaper lithium ion secondary batteries not only for small secondary batteries for portable devices, but also for large secondary batteries for power storage and electric vehicles. It can be said that the realization of this is of great industrial significance. In particular, secondary batteries for hybrid vehicles, which are rapidly becoming popular, are required to have high output, and high output lithium-ion secondary batteries are being studied.

As a new active material for lithium-ion secondary batteries, a lithium-nickel composite oxide using nickel, which is cheaper than cobalt, can be mentioned. Since this lithium-nickel composite oxide exhibits a lower electrochemical potential than the lithium-cobalt composite oxide, decomposition due to oxidation of the electrolytic solution is less likely to be a problem, and higher capacity can be expected. Therefore, it is actively developed. However, when a lithium-ion secondary battery is produced using a lithium-nickel composite oxide synthesized purely from nickel as a positive electrode material, the cycle characteristics are inferior to those of the cobalt-based battery, and the use and storage in a high-temperature environment result in a relatively high temperature. Lithium-nickel composite oxides in which a portion of nickel is replaced with cobalt or aluminum are generally known because they have the drawback of easily impairing battery performance.

It is known that increasing the output of the lithium-nickel composite oxide is effective by increasing the reaction area with the electrolytic solution, specifically by increasing the surface area by reducing the particle size. As a general method for producing a lithium-nickel composite oxide as a positive electrode active material, a nickel composite hydroxide as a precursor is produced by a neutralization crystallization method, and this precursor is mixed with a lithium compound and calcined. , methods of obtaining lithium-nickel composite oxides are known. The powder properties of the lithium-nickel composite oxide are greatly affected by the powder properties of the precursor nickel composite hydroxide. In particular, the particle size distribution, which is the most basic powder property, almost reflects the particle size distribution of the precursor. Therefore, control of neutralization crystallization to obtain the precursor is extremely important.

In other words, in order to obtain a high-power lithium-nickel composite oxide, it is necessary to obtain a fine nickel composite hydroxide by neutralization crystallization. Also, to increase the capacity of the lithium-nickel composite oxide, it is effective to increase the volumetric energy density by improving the filling property, and as a method for improving the filling property, it is effective to improve the circularity of the particles. Therefore, in order to obtain a lithium-nickel composite oxide with high output and high capacity, it is preferable to use a nickel composite hydroxide having a small particle size and a high degree of circularity as a precursor.

In Patent Document 1, the sphericity of primary particles or secondary particles (= area circle equivalent diameter of particle projection image / minimum circumscribed circle diameter of particle projection image) is 0.3 to 0.95, and the primary particles or secondary particles A positive electrode active material for a lithium ion battery is presented, in which the volume average particle size of the secondary particles is 2 to 8 μm, the specific surface area is 0.3 to 1.8 m 2 /g, and the tap density is 2.0 g/cm 3 or more. ing. However, only those with an average particle size of 4.2 μm to 6.8 μm are described as examples, and no positive electrode active material with an average particle size of about 4 μm or less is disclosed. Therefore, Patent Document 1 does not provide a technique for realizing a positive electrode active material with a truly small particle size.

Patent Document 2 discloses a positive electrode active material for a non-aqueous lithium secondary battery, which is a particle composed of a composite oxide of lithium and a transition metal, and at least the surface of which is melted and solidified to be spherical. However, although it is thought that melting the surface increases the degree of circularity, the finer the particle size of the positive electrode active material, the easier it is to aggregate. will do. This results in an increase in particle size, which is presumed to greatly reduce the filling property of the positive electrode active material and reduce the output of the battery. Therefore, Patent Document 2 also does not provide a technique for realizing a positive electrode active material with a truly small particle size.

Patent Document 3 describes that the lower the degree of circularity, the easier it is for the primary particles inside the secondary particles to come into contact with the conductive aid, so the output increases (paragraph 0023). Since it is clear that the lowering of the temperature significantly lowers the fillability, it cannot be considered that both high output and high capacity of the battery have been achieved.

As described above, it has been difficult with conventional techniques to achieve both high output and high capacity, that is, to obtain a lithium-nickel composite oxide with a fine particle size and a high degree of circularity.

WO2011-083648 Japanese Patent Application Laid-Open No. 2002-110156 JP-A-2008-186753

In view of the above circumstances, it is an object of the present invention to provide a nickel-containing hydroxide as a raw material of a positive electrode active material for a non-aqueous electrolyte secondary battery that can achieve both high output and high capacity, and a method for producing the same. .

As a result of intensive research on a method for producing a nickel-containing hydroxide, which is a raw material for a positive electrode active material for a non-aqueous electrolyte secondary battery, the present inventor found that the nickel-containing hydroxide slurry during crystallization is accelerated at a certain level or more. The present inventors have completed the present invention based on the knowledge that a nickel-containing oxide having a fine grain size and high spherical shape can be obtained by providing

The nickel-containing hydroxide of the first invention has the general formula (1) Ni1-x-yCoxAly(OH)2+α (0≤x≤0.3, 0.005≤y≤0.15, x+y<0. 5, 0 ≤ α ≤ 0.5, M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) or general formula (2) NixCoyMnzMt (OH ) 2 + α (x + y + z + t = 1, 0.1 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.8, 0 ≤ t ≤ 0.02, 0 ≤ α ≤ 0.5, M is Ti, V , Cr, Zr, Nb, Mo, Hf, Ta, and one or more additive elements selected from W). The volume average particle diameter is 1.00 μm to 3.00 μm, the index indicating the spread of the particle size distribution [(d90−d10)/volume average particle diameter] is 0.50 or less, and the circularity ( The area circle equivalent diameter of the projected particle image/minimum circumscribed circle diameter of the projected particle image) is 0.95 or more.
The method for producing a nickel-containing hydroxide of the second invention is represented by the general formula (1) Ni1-x-yCoxAly(OH)2+α (0 ≤ x ≤ 0.3, 0.005 ≤ y ≤ 0.15, x + y <0.5, 0 ≤ α ≤ 0.5, M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) or general formula (2) NixCoyMnzMt(OH)2+α(x+y+z+t=1, 0.1≤y≤0.5, 0.1≤z≤0.8, 0≤t≤0.02, 0≤α≤0.5, M is One or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W), which is a raw material of a positive electrode active material for non-aqueous electrolyte secondary batteries. A method for producing an oxide, comprising supplying a metal salt-containing aqueous solution, an alkali metal hydroxide, and a complexing agent while stirring a reaction solution, and reacting them to obtain neutralized crystals containing nickel-containing hydroxide particles. In the analysis step, there is a region where the acceleration of the slurry containing nickel-containing hydroxide particles is 900 m / s or more when simulated using ANSYS CFX Ver15.0 fluid analysis software. The volume average particle diameter of the contained hydroxide is 1.00 μm to 3.00 μm, and the index [(d90-d10)/volume average particle diameter], which is an index showing the spread of the particle size distribution, is 0.50 or less. The degree (equivalent area circle diameter of projected particle image/minimum circumscribed circle diameter of projected particle image) is set to 0.95 or more .
A method for producing a nickel-containing hydroxide according to a third aspect of the invention is characterized in that, in the second aspect of the invention, an acceleration applying mechanism is used as the method of applying acceleration to the slurry.
A method for producing a nickel-containing hydroxide according to a fourth invention is characterized in that, in the third invention, the acceleration adding mechanism is a centrifugal pump.

According to the first invention, the nickel-containing hydroxide has a small volume average particle size of 1.00 μm to 4.00 μm, so that the specific surface area can be increased and high output can be exhibited. When the spread of the distribution [(d90−d10)/volume average particle diameter] is 0.5 or less, the amount of fine particles mixed can be reduced to ensure high output of the battery. Further, when the degree of circularity is 0.95 or more, the filling property of the positive electrode active material can be increased, so that the high capacity of the battery can be achieved. Thus, according to the nickel-containing hydroxide of the first invention, both high output and high capacity of the battery can be achieved.
According to the second invention, in the region where the acceleration is 900 m/s2 or more, the particles that have grown into an irregular shape different from a spherical shape are subjected to a large shearing force, crushed and spheroidized, and the particle size is reduced while maintaining the sphericity. grow up. Therefore, the volume average particle diameter is 1.00 μm to 3.00 μm, and [(d90−d10)/volume average particle diameter], which is an index showing the spread of the particle size distribution, is 0.00 μm to 3.00 μm. 50 or less , and the degree of circularity (equivalent area circle diameter of projected particle image/minimum circumscribed circle diameter of projected particle image) can be kept at 0.95 or more .
According to the third invention, since the acceleration of the slurry can be increased efficiently with lower energy, it is possible to efficiently obtain nickel-containing hydroxide particles having a small particle size and a high degree of sphericity.
According to the fourth invention, if a centrifugal pump is used, the slurry can be accelerated radially outward by the rotation of the impeller housed in the casing of the centrifugal pump, and the acceleration can easily realize high acceleration by increasing the rotation speed. Therefore, it is suitable for applications where slurry is accelerated at high speed.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of the nickel containing hydroxide which concerns on this invention, and its manufacturing method.

An embodiment of the present invention will be described below with reference to the drawings.
(Nickel-containing hydroxide)
First, the nickel-containing hydroxide according to the present invention will be explained.
The nickel-containing hydroxide of the present invention has (1) general formula: Ni1-x-yCoxAly(OH)2+α (0≤x≤0.3, 0.005≤y≤0.15, x+y<0. 5, 0 ≤ α ≤ 0.5) or (2) general formula: NixCoyMnzMt(OH) 2 + α (x + y + z + t = 1, 0.1 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.8, 0 ≤ t ≤ 0.02, 0 ≤ α ≤ 0.5, M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W It is a nickel-containing hydroxide that serves as a raw material for a positive electrode active material for aqueous electrolyte secondary batteries.
The nickel-containing hydroxide particles have (a) a volume average particle diameter of 1.00 μm to 4.00 μm, and (b) an index showing the spread of the particle size distribution [(d90−d10)/volume average particle size] is 0.50 or less, and (c) circularity (diameter equivalent to area circle of projected particle image/minimum circumscribed circle diameter of projected particle image) is 0.95 or more. It is characterized by

(a) Volume average particle size [MV]
Volume mean particle size (MV) is the mean particle size weighted by particle volume, which in a set of particles is the sum of the diameters of individual particles multiplied by their volumes divided by the total volume of the particles. be. The volume average particle diameter (MV) can be measured, for example, by a laser diffraction scattering method using a laser diffraction particle size distribution meter. Since the volume average particle diameter is as small as 1.00 μm to 4.00 μm, it is possible to increase the specific surface area and exhibit high output.

If the above numerical range is exceeded, the following problems arise. A volume-average particle size of less than 1.00 μm is not preferable because the paste viscosity significantly increases when an electrode is produced using a positive electrode active material using this as a raw material. On the other hand, if the volume average particle diameter exceeds 4.00 μm, the specific surface area of the positive electrode active material using this as a raw material is reduced, and the movement of lithium is restricted, so that sufficient output cannot be exhibited.

(b) Volume particle size distribution [(d90-d10) / volume average particle size], which is an index showing the spread of particle size distribution (particle size variation index), is 0.50 or less, so that fine particles and coarse particles are mixed is suppressed, the particle size of the secondary particles becomes uniform, and high power output of the battery can be realized. In addition, since an increase in paste viscosity during electrode preparation can be suppressed, the amount of solvent can be reduced, the drying process after coating can be shortened, and there is the advantage that drying shrinkage is small and the yield is improved.

On the other hand, when [(d90-d10)/volume average particle diameter] exceeds 0.50, the amount of submicron or smaller fine particles mixed in increases, which is not preferable because the viscosity of the paste increases significantly during electrode production as in the above case. .
Note that d90 and d10 mean particle diameters accumulated from the smaller particle diameter side, and the cumulative volume becomes 90% and 10% of the total volume of all particles, respectively. d90 and d10 can be measured by a laser diffraction scattering method using a laser diffraction particle size distribution meter, like the volume average particle diameter (MV).

(c) Circularity Circularity as referred to in this specification is determined by [area equivalent circle diameter of projected particle image/minimum circumscribed circle diameter of projected particle image]. The closer this value is to 1, the closer the particles are to a perfect circle. Also, since particles are three-dimensional, it is best to use sphericity as an index, but this is difficult, so circularity is used instead.
However, the method for measuring the area circle equivalent diameter of the projected particle image and the minimum circumscribed circle diameter of the projected particle image can be obtained from the projected image of the particle measured with a commercially available electron microscope.

In the present invention, since the degree of circularity is set to 0.95 or more, the sphericity is considerably high, and the filling property of the positive electrode active material can be maintained at a high level. Therefore, the volumetric energy density of the battery can be maintained within a suitable range.
On the other hand, when the degree of circularity is less than 0.95, the positive electrode active material made from this material is less filling, resulting in a decrease in volumetric energy density of the battery, which is not preferable.

As described above, the present invention is characterized in that (a) volume average particle diameter, (b) particle size distribution, and (c) circularity all satisfy the above numerical ranges. High battery output is achieved by (a) volume average particle size and (b) particle size distribution, and high capacity is achieved by (c) circularity. Therefore, the present invention can achieve both high output and high capacity.

(Production method)
Next, the method for producing the nickel-containing hydroxide of the present invention will be explained.
The method for producing a nickel-containing hydroxide according to the present invention includes (1) general formula: Ni1-x-yCoxAly(OH)2+α (0≤x≤0.3, 0.005≤y≤0.15, x+ y < 0.5, 0 ≤ α ≤ 0.5) or (2) general formula: NixCoyMnzMt(OH) 2 + α (x + y + z + t = 1, 0.1 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0 .8, 0≤t≤0.02, 0≤α≤0.5, M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W; A method for producing a nickel-containing hydroxide, which is a raw material for a positive electrode active material for a non-aqueous electrolyte secondary battery represented by the above, wherein a metal salt-containing aqueous solution, an alkali metal hydroxide, and a complex In the neutralization and crystallization step of supplying and reacting an agent to obtain nickel-containing hydroxide particles, the slurry containing nickel-containing hydroxide particles has a region where the acceleration is 900 m/s2 or more. do.

The metal salt-containing aqueous solution is an aqueous solution obtained by dissolving the salt of each constituent element of the nickel-containing hydroxide in water to adjust the salt concentration. The composition of the metal salt-containing aqueous solution is preferably the composition ratio of the metal elements in the general formula.

By supplying the alkali metal hydroxide, the pH of the reaction solution (the nickel composite hydroxide solution after the reaction) can be controlled. Alkali metal hydroxides are not particularly limited, and for example, aqueous solutions of alkali metal hydroxides such as sodium hydroxide and potassium hydroxide can be used. Although the alkali metal hydroxide can be added directly to the reaction solution, it is preferably added as an aqueous solution for ease of pH control.
The method of adding the alkali metal hydroxide aqueous solution is not particularly limited, either. While sufficiently stirring the reaction solution, a pump capable of controlling the flow rate such as a metering pump is used, and the pH at a liquid temperature of 25 ° C. is 10 to 10. 13 (! Comparative Example 3!).

The complexing agent is not particularly limited as long as it is an ammonium ion donor, and any one capable of forming a nickel ammine complex in the reaction aqueous solution can be used. Examples include ammonia, ammonium sulfate, ammonium chloride, ammonium carbonate, and ammonium fluoride.
In addition to the ammonium ion donor, any substance that forms the aforementioned complex can be used, and examples thereof include ethylenediaminetetraacetic acid, nitritotriacetic acid, uracildiacetic acid and glycine. Among these, it is more preferable to use aqueous ammonia from the viewpoint of ease of handling.

In the production process of the present invention, a region with an acceleration of 900 m/s2 or more is provided, and when the slurry is passed through this region, the particles that have grown into irregular shapes different from spheres receive a large shear force and are crushed into spheres. . Then, the grain size grows while maintaining the sphericity.
This will be explained more specifically. In the neutralization and crystallization step, a large number of secondary particles are produced by agglomeration of primary particles, which become nickel-containing hydroxide particles. When a large number of secondary particles are combined by agglomeration, they become irregularly shaped particles with low sphericity. Such deformed particles are sheared by being accelerated in the slurry, the number of aggregates is reduced, and finally separated into individual secondary particles. As a result of the separation, the nickel-containing hydroxide particles become spherical as they should be.

When applying the shear force as described above, it is effective to set the acceleration to 900 m/s2 or more. On the other hand, if there is no region where the acceleration is 900 m/s2 or more, that is, if the maximum acceleration in the system is less than 900 m/s2, the shear force on the particles is insufficient, and the average particle diameter of 3.00 μm or less is reduced. It is not preferable because it becomes difficult to obtain particles having such a particle size and the sphericity tends to decrease.

(Method of giving acceleration)
Any method may be used in the method for producing a nickel-containing hydroxide of the present invention as long as it can impart the required acceleration to the slurry. For example, in addition to a pump, a stirrer, a centrifuge, or the like can be used as the acceleration adding mechanism. However, it is more efficient to use a pump to give a high acceleration of 900 m/s2 or more. The reason why the pump is efficient is that it can increase the acceleration of the slurry efficiently with less energy. Further, in addition to the pump, an orifice or a reducer in which the diameter of the slurry passage is partially narrowed can be used as the acceleration adding mechanism. By narrowing the flow path, the flow velocity of the slurry can be further accelerated. In addition, when the inside of the tank can be sufficiently stirred by the amount of circulation by the pump, the stirrer 2 used for stirring the inside of the tank can be omitted.

The manufacturing facility shown in FIG. 1 is preferably used for the method of using a pump as the acceleration adding mechanism.
1 is a reaction tank and 2 is a stirrer for stirring the slurry. A pump 3 is connected to the reaction tank 1 by a suction pipe 4 and a return pipe 5, and the pump 3 can apply acceleration to the slurry.
Using the above manufacturing equipment, the slurry is introduced into the pump 3 from the reaction tank 1 and returned from the pump 3 to the reaction tank 1, that is, if a method of circulation is adopted, it can be continuously accelerated at small flow rates, resulting in high energy efficiency. It is preferable in that In such equipment, a slurry acceleration region can be provided inside the pump 3 or inside the flow paths of the pump pipes 4 and 5 .

In the present invention, when a pump is used, centrifugal pumps, diaphragm pumps, screw pumps, gear pumps, hose pumps and the like are generally used. However, the pump used in the present invention is preferably a centrifugal pump. A centrifugal pump can accelerate the slurry radially outward with an impeller installed in the casing, and the acceleration can easily achieve high acceleration by increasing the rotation speed, so it is suitable for applications that accelerate the slurry at high speed. Better than other pumps.

(Effects of the manufacturing method of the present invention)
As described above, when the centrifugal pump 3 accelerates the slurry at a high speed, the secondary particles bound in an abnormal shape are separated from each other, so that the monodispersity and sphericity of the nickel-containing hydroxide can be improved. Moreover, by producing a positive electrode active material using nickel-containing oxide particles having a small particle size, dispersibility, and spherical properties, both the output and capacity of a non-aqueous electrolyte secondary battery can be improved.

The present invention will be explained in more detail by means of examples and comparative examples.
In the following examples and comparative examples, the particle size distribution was measured using a laser diffraction particle size distribution meter (MT3300EX2 manufactured by Microtrack Bell Co., Ltd.). A wet flow particle size/shape analyzer (manufactured by Malvern Instruments Ltd., FPIA-3000) was used to measure the circularity.
In addition, in the present Examples, reagent special grade samples manufactured by Wako Pure Chemical Industries, Ltd. were used for the production of nickel-containing hydroxides.

(Example 1)
40 L of pure water, a 25% caustic soda solution as an alkali metal hydroxide, and a 25% aqueous ammonia solution as a complexing agent were added to a 200 L crystallization reaction tank equipped with four baffles, and the tank was heated at 25°C. The internal pH was adjusted to 12.40, and the ammonia concentration in the tank was adjusted to 12 g/L. While stirring the inside of the reaction vessel maintained at 40° C. at 280 rpm using a 6-blade flat turbine blade with a diameter of 25 cm, using a metering pump, the molar concentration of nickel is 1.4 mol / L and the molar concentration of cobalt is 0.3 mol / L. 580 ml/min of a mixed aqueous solution of nickel-cobalt sulfate and 92 ml/min of an aqueous sodium aluminate solution having an aluminum concentration of 0.43 mol/L were supplied, and a 25% caustic soda solution and a 25% aqueous ammonia solution were intermittently added. The pH at °C was controlled to be 12.40 and the ammonia concentration to be maintained at 12 g/L. At the same time, the slurry in the tank was circulated at a frequency of 10 Hz (impeller rotation speed: 520 rpm) using a centrifugal pump (HDS13-25WJ, manufactured by Sprout Kogyo Co., Ltd., capacity: 11 kW). After 4 hours from the start of the reaction, the raw material supply pump and the centrifugal pump were stopped, and the nickel-containing hydroxide slurry was filtered and dried to obtain powdery nickel-containing hydroxide.
When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 1.6 μm, D50: 2.1 μm, D90: 2.6 μm, volume average particle size: 2.2 μm, (D90-D10)/volume The average particle size was 0.45 and the degree of circularity was 0.99.

(Example 2)
A nickel-containing hydroxide was obtained by using a 7.5 kW stirrer and increasing the rotational speed to 500 rpm without using the centrifugal pump in Example 1. When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 1.9 μm, D50: 2.3 μm, D90: 3.0 μm, volume average particle diameter: 2.5 μm, (D90-D10) / volume Average particle size: 0.44, Circularity: 0.97.

(Example 3)
In Example 1, instead of the nickel-cobalt sulfate mixed aqueous solution, a nickel-cobalt-manganese mixed aqueous solution having a nickel molar concentration of 0.6 mol/L, a cobalt molar concentration of 0.6 mol/L, and a manganese molar concentration of 0.6 mol/L was used. A contained hydroxide was obtained.
When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 1.7 μm, D50: 2.0 μm, D90: 2.7 μm, volume average particle diameter: 2.2 μm, (D90-D10)/volume The average particle size was 0.45 and the degree of circularity was 0.97.

(Comparative example 1)
A nickel-containing hydroxide was obtained by using the centrifugal pump of Example 1 and setting the frequency to 7 Hz (impeller rotation speed: 360 rpm).
When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 2.9 μm, D50: 3.6 μm, D90: 4.8 μm, volume average particle diameter: 3.9 μm, (D90-D10) / volume The average particle size was 0.49 and the degree of circularity was 0.94.

(Comparative example 2)
A nickel-containing hydroxide was obtained by using the stirrer in Example 2 and rotating the stirrer at 350 rpm.
When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 3.4 μm, D50: 4.3 μm, D90: 5.5 μm, volume average particle size: 4.6 μm, (D90-D10)/volume The average particle size was 0.46 and the degree of circularity was 0.93.

(Comparative Example 3)
A nickel-containing hydroxide was obtained by using the stirrer in Example 2 and rotating the stirrer at 200 rpm.
When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 2.1 μm, D50: 2.8 μm, D90: 4.0 μm, volume average particle diameter: 2.9 μm, (D90-D10)/MV : 0.66, circularity 0.91.

(Comparative Example 4)
In Comparative Example 1, instead of the nickel-cobalt sulfate mixed aqueous solution, a nickel-cobalt-manganese mixed aqueous solution having a nickel molarity of 0.6 mol/L, a cobalt molarity of 0.6 mol/L, and a manganese molarity of 0.6 mol/L was used. A contained hydroxide was obtained.
When the particle size distribution of the obtained nickel-containing hydroxide was measured, D10: 2.3 μm, D50: 2.9 μm, D90: 4.2 μm, volume average particle diameter: 3.0 μm, (D90-D10) / volume The average particle size was 0.63 and the degree of circularity was 0.90.

In Examples 1 to 3 and Comparative Examples 1 to 4, the acceleration at the point of maximum acceleration in the system was obtained by simulation using general-purpose fluid analysis software. ANSYS CFX Ver15.0 (trade name) manufactured by ANSYS was used as fluid analysis software. Among the regions for fluid analysis, the area around the stirring shaft and stirring blades is handled in a rotating coordinate system that rotates together with the stirring shaft and stirring blades. The area handled by the rotating coordinate system is cylindrical, the center line of which overlaps the center line of the stirring shaft or the stirring blade, the diameter is set to 115% of the blade diameter of the stirring blade, and the vertical range is stirred. From the inner bottom surface of the tank to the liquid surface. Other areas of the analysis area were handled in the stationary coordinate system, and the rotating coordinate system and the stationary coordinate system were connected using "Frozen Rotor", which is an interface function of the fluid analysis software. Since the flow in the stirring vessel is turbulent, the SST (Shear Stress Transport) model was used as the turbulence model for calculation.
As a result, it was confirmed that in Examples 1 and 3 and Comparative Example 1, it was the largest around the impeller of the centrifugal pump, and in Example 2 and Comparative Examples 2 to 4, it was largest around the stirring blades. Table 1 shows the maximum acceleration, volume average particle size, and circularity.

From Table 1 above, the volume average particle diameter is 1.00 μm to 3.00 μm by reacting in a system having a region where the acceleration is 900 m / s2 or more in the system, which is an index showing the spread of the particle size distribution. It was confirmed that particles having a [(d90−d10)/volume average particle diameter] of 0.50 or less and a circularity of 0.95 or more can be obtained.
The nickel-containing oxide particles obtained in Examples and Comparative Examples were calcined in air at a temperature of 800° C. for 2 hours, and the nickel-containing oxide particles were recovered. Lithium hydroxide was weighed so that Li/Me = 1.02 and mixed with the recovered nickel-containing oxide particles to form a mixture. Mixing was performed using a shaker mixer device (TURBULA Type T2C manufactured by Willie & Bacchofen (WAB)). The resulting mixture was calcined at 750 ° C. for 8 hours in an oxygen stream (oxygen: 100% by volume) in Examples 1, 2 and Comparative Examples 1, 2, and 3, and in Example 3 and Comparative Example 4, an air stream. The mixture was fired at 950° C. for 8 hours in medium (oxygen: 20% by volume), cooled, and crushed to obtain a positive electrode active material.
Table 2 shows the volume average particle size and tap density of the positive electrode active material.

Normally, in the particle size range of Table 2 above, the tap density tends to decrease as the particle size becomes finer. It was confirmed that the energy density of the battery was improved. This is due to the high degree of circularity, in other words, the high degree of sphericity of the precursor nickel composite hydroxide particles.

1 Reaction Tank 2 Stirrer 3 Pump

Claims (4)

A nickel-containing hydroxide that is a raw material for a positive electrode active material for a non-aqueous electrolyte secondary battery represented by the following general formula (1) or (2), and has a volume average particle size of 1.00 μm to 3.00 μm and [(d90-d10)/volume average particle diameter], which is an index showing the spread of the particle size distribution, is 0.50 or less, and the degree of circularity (the area circle equivalent diameter of the projected particle image/minimum circumscription of the projected particle image A nickel-containing hydroxide characterized by having a circular diameter) of 0.95 or more.
(1) Ni1-xyCoxAly(OH)2+α (0≤x≤0.3, 0.005≤y≤0.15, x+y<0.5, 0≤α≤0.5, M is Ti , V, Cr, Zr, Nb, Mo, Hf, Ta, and one or more additive elements selected from W)
(2) Ni Coy Mnz Mt (OH) 2 + α (x + y + z + t = 1, 0.1 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.8, 0 ≤ t ≤ 0.02, 0 ≤ α ≤ 0.5 , M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) A method for producing a nickel-containing hydroxide as a raw material for a positive electrode active material for a non-aqueous electrolyte secondary battery represented by the following general formula (1) or (2), comprising: while stirring a reaction solution, metal salt In the neutralization crystallization step in which the aqueous solution, alkali metal hydroxide, and complexing agent are supplied and reacted to obtain nickel-containing hydroxide particles, the acceleration of the slurry containing nickel-containing hydroxide particles is determined by ANSYS When simulated using the fluid analysis software of ANSYS CFX Ver15.0 manufactured by ANSYS CFX Ver. and [(d90-d10)/volume average particle diameter], which is an index showing the spread of the particle size distribution, is 0.50 or less, and the degree of circularity (area circle equivalent diameter of the projected particle image/minimum circumscribed circle of the projected particle image diameter) of 0.95 or more .
(1) Ni1-xyCoxAly(OH)2+α (0≤x≤0.3, 0.005≤y≤0.15, x+y<0.5, 0≤α≤0.5, M is Ti , V, Cr, Zr, Nb, Mo, Hf, Ta, and one or more additive elements selected from W)
(2) Ni Coy Mnz Mt (OH) 2 + α (x + y + z + t = 1, 0.1 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.8, 0 ≤ t ≤ 0.02, 0 ≤ α ≤ 0.5 , M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W ) 3. The method for producing a nickel-containing hydroxide according to claim 2, wherein a pump is used as a method of applying acceleration to said slurry. 4. The method for producing nickel-containing hydroxide according to claim 3, wherein said pump is a centrifugal pump.

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