JP7031535B2 - Method for producing nickel-containing hydroxide - Google Patents

Description

The present invention relates to a method for producing a nickel-containing hydroxide.

As batteries for mobile information terminals such as mobile phones, smartphones, tablet PCs, and notebook PCs, small and lightweight non-aqueous electrolyte secondary batteries having high energy density are being developed. In addition, with the spread of hybrid electric vehicles (HEV) and clean energy vehicles such as electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV), the development of higher capacity and higher output non-aqueous electrolyte secondary batteries. Is also progressing.

As a non-aqueous electrolyte secondary battery satisfying such a requirement, there is a lithium ion secondary battery. The lithium ion secondary battery includes a positive electrode, a negative electrode, an electrolyte and the like. For the positive electrode and the negative electrode, a positive electrode active material and a negative electrode active material are used as the positive electrode material and the negative electrode material. Materials capable of desorbing and inserting lithium are used for the positive electrode active material and the negative electrode active material.

As one of the methods for improving the performance of the lithium ion secondary battery, improvement of the positive electrode active material of the lithium ion secondary battery is being studied, and as the positive electrode active material, a layered or spinel type lithium metal composite oxide is used. There is a method to use. Since a lithium ion secondary battery using a lithium metal composite oxide as a positive electrode active material can obtain a high voltage of 4V class, it is being put into practical use as a lithium ion secondary battery having a high energy density.

As the lithium metal composite oxide, a lithium manganese composite oxide (LiMn ₂ O ₄ ), a lithium cobalt composite oxide (LiCoO ₂ ), a lithium nickel composite oxide (LiNiO ₂ ) and the like are generally known. Among these, lithium nickel composite oxide is attracting attention as a material capable of increasing the capacity of lithium ion secondary batteries, and lithium nickel in which a part of nickel in the lithium nickel composite oxide is replaced with cobalt, aluminum, manganese, or the like. Development of composite oxides is in progress.

Lithium-nickel composite oxides are generally nickel-containing hydroxides that are precursors of lithium-nickel composite oxides by neutralization crystallization method (nickel-containing hydroxides containing metals other than nickel are nickel composite hydroxides. It is produced by producing particles of), mixing nickel-containing hydroxide particles with a lithium compound, and firing them. The nickel-containing hydroxide particles are subjected to nucleation by a neutralization crystallization method in a tank containing a raw material liquid that is a raw material for nickel-containing hydroxide to form an agglomerate composed of a plurality of nuclei, and then the agglomerate. It is obtained by forming an outer shell on the outer circumference of the shell.

For example, Patent Document 1 describes nickel-containing water including a nucleation generation step of forming nuclei of nickel-containing hydroxide particles by neutralization crystallization in an aqueous solution in a stirring tank and a particle growth step of growing nuclei. A method for producing an oxide is disclosed. In the particle growth step, after forming an agglomerate composed of a plurality of grown nuclei, an outer shell is formed around the agglomerate. As a result, particles of a nickel-containing hydroxide composed of an agglomerate and an outer shell formed around the agglomerate are produced.

International Publication No. 2017/217365

By the way, in order to use a lithium nickel composite oxide as a positive electrode active material in the future, there is a need for a method capable of adjusting the lithium nickel composite oxide to a predetermined size for production.

Since the lithium nickel composite oxide is obtained by mixing a lithium compound with its precursor nickel-containing hydroxide and firing it, the size of the lithium nickel composite oxide is the size of the nickel-containing hydroxide. Tends to depend. The nickel-containing hydroxide is a particle containing a plurality of nuclear aggregates and an outer shell generated by the neutralization crystallization method at the time of its production, and the size of the nickel-containing hydroxide is the size of the aggregate. It depends on. Therefore, in order to control the size of the nickel-containing hydroxide, it is important to adjust the size of the agglomerates generated in the process of producing the nickel-containing hydroxide.

One aspect of the present invention is to provide a method for producing a nickel-containing hydroxide capable of adjusting the particle size of agglomerates produced during the production of the nickel-containing hydroxide with high accuracy.

（但し、式（I）中、Ｒは凝集体の半径であり、Ａはモデル係数であり、ｒは核の半径であり、Ｃは過飽和度であり、Ｃ_Ｔは過飽和度Ｃの閾値であり、Ｎは原料液の添加口の数であり、ΔＶは過飽和度Ｃがｃからｃ＋Δｃまでの領域の体積であり、ｕは過飽和度Ｃがｃからｃ＋Δｃまでの領域を通過する流体の平均流速であり、Ｋは過飽和度Ｃがｃからｃ＋Δｃまでの領域を通過する流体の流れの乱流拡散係数であり、Ｂはモデル係数であり、ωは撹拌翼の回転数であり、Ｌ_ｐは撹拌翼の翼径である。） The method for producing a nickel-containing hydroxide according to one aspect of the present invention comprises a raw material solution containing at least a metal salt containing a nickel salt, a complexing agent that binds to a metal ion of the metal salt to form a complex, and the like. A method for producing a nickel-containing hydroxide in which a nickel-containing hydroxide is obtained by neutralization crystallization in a reaction aqueous solution containing the metal salt and a neutralizing agent that reacts with the complex to produce a metal hydroxide. There,
In the reaction aqueous solution, a seed crystal generation step of growing the nucleus of the nickel-containing hydroxide generated by neutralization crystallization to generate a seed crystal is included.
The seed crystal forming step is a first kind crystal forming step in which the nuclei of the nickel-containing hydroxide are generated by neutralization crystallization in the reaction aqueous solution to form an aggregate in which a plurality of the nuclei are aggregated. Including,
A method for producing a nickel-containing hydroxide, wherein the first-class crystal forming step is carried out under the conditions set based on the following formula (I).

(However, in equation (I), R is the radius of the aggregate, A is the model coefficient, r is the radius of the nucleus, _C is the degree of supersaturation, and CT is the threshold of the degree of supersaturation C. , N is the number of addition ports of the raw material liquid, ΔV is the volume of the region where the supersaturation degree C is from c to c + Δc, and u is the average flow velocity of the fluid passing through the region where the supersaturation degree C is from c to c + Δc. Yes, K is the turbulent diffusion coefficient of the flow of fluid passing through the region where the supersaturation degree C passes from c to c + Δc, B is the model coefficient, ω is the rotation speed of the stirring blade, and L _p is the stirring blade. The wing diameter of.)

The method for producing a nickel-containing hydroxide according to one aspect of the present invention can adjust the particle size of the aggregates produced during the production of the nickel-containing hydroxide with high accuracy.

It is a flowchart of the manufacturing method of the nickel-containing hydroxide according to one Embodiment. It is a figure which shows an example of the aggregate generated in the 1st kind crystal formation process schematically. It is sectional drawing which shows typically an example of the seed crystal particle formed in the 2nd kind crystal generation step. It is sectional drawing which shows typically the particle of the nickel-containing hydroxide produced in the growth crystallization step. It is a top view which shows the chemical reaction apparatus used in the manufacturing method of the nickel-containing hydroxide by one Embodiment. It is sectional drawing of the chemical reaction apparatus along the line I-I of FIG. It is explanatory drawing which shows an example of the model of the state in which the nuclear particle is aggregated in the aggregate. It is a figure which shows the highly supersaturated region formed in the vicinity of the addition port of a raw material liquid. It is a figure which shows the relationship between the calculated value and the measured value of the average particle diameter of an aggregate.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

In explaining the method for producing a nickel-containing hydroxide according to the embodiment, first, the nickel-containing hydroxide obtained by using the method for producing the nickel-containing hydroxide according to the embodiment will be described.

<Nickel-containing hydroxide>
Nickel-containing hydroxides are used as precursors for positive electrode active materials in lithium-ion secondary batteries. Nickel-containing hydroxides are particles formed by the growth of fine nuclei of nickel-containing hydroxides.

The nickel-containing hydroxide contains nickel (Ni), and preferably contains a metal other than Ni. As the metal other than Ni, one or more elements selected from the group consisting of Co, Mn, Al, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta and W can be used. A nickel-containing hydroxide further containing a metal other than Ni is called a nickel composite hydroxide.

As the nickel-containing hydroxide, a nickel composite hydroxide such as a nickel cobalt manganese composite hydroxide or a nickel cobalt aluminum composite hydroxide can be preferably used.

Nickel composite hydroxides include, for example, (1) nickel (Ni), cobalt (Co), manganese (Mn), and M (M is from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W. One or more added elements to be selected) and the substance amount ratio (mol ratio) is Ni: Co: Mn: M = x: y: z: t (however, x + y + z + t = 1, 0.1 ≦ x ≦ 0). .7, 0.1 ≤ y ≤ 0.5, 0.1 ≤ z ≤ 0.8, 0 ≤ t ≤ 0.02) Nickel cobalt-cobalt-manganese composite hydroxide, or (2) nickel (2) Ni), cobalt (Co) and aluminum (Al) have a substance amount ratio (mol ratio) of Ni: Co: Al = 1-xy: x: y (however, 0 ≦ x ≦ 0.3, 0). A nickel-cobalt-aluminum composite hydroxide containing .005 ≦ y ≦ 0.15) can be used.

The amount of hydroxide ion contained in the nickel-containing hydroxide usually has a stoichiometric ratio, but it may be excessive or deficient to the extent that it does not affect the present embodiment. Further, a part of the hydroxide ion may be replaced with an anion (for example, carbonate ion, sulfate ion, etc.) to the extent that it does not affect the present embodiment.

The nickel-containing hydroxide may be a single phase of the nickel-containing hydroxide (or a nickel-containing hydroxide whose main component is nickel-containing hydroxide) as measured by X-ray diffraction (XRD).

When a positive electrode active material is obtained from a nickel composite hydroxide as a raw material, the metal composition ratio of the nickel composite hydroxide (for example, Ni: Co: Al or Ni: Co: Mn: M) is the obtained positive electrode active material. It is also maintained in. Therefore, the composition of the nickel composite hydroxide is adjusted to match the composition ratio of the metal required for the positive electrode active material.

<Manufacturing method of nickel-containing hydroxide>
Next, a method for producing a nickel-containing hydroxide according to one embodiment will be described. The method for producing a nickel-containing hydroxide according to one embodiment is a method for obtaining particles of the nickel-containing hydroxide by neutralization crystallization. FIG. 1 is a flowchart of a method for producing a nickel-containing hydroxide according to an embodiment. As shown in FIG. 1, in the method for producing a nickel-containing hydroxide according to an embodiment, a seed crystal that grows a nucleus of a nickel-containing hydroxide generated in a reaction aqueous solution to generate a granular seed crystal. The production step S11 and the growth crystallization step S12 for forming an outer shell portion on the surface of the seed crystal are included.

In this embodiment, a batch type stirring tank is used for both the seed crystal generation step S11 and the growth crystallization step S12. Hereinafter, each step will be described.

[Seed crystal generation process]
The seed crystal generation step S11 will be described. In the seed crystal generation step S11, fine nuclei (nuclear particles) of nickel-containing hydroxide are generated in the reaction aqueous solution by neutralization crystallization (nuclear generation). Then, the generated nuclear particles are grown (particle growth) to generate particulate seed crystals (seed crystal particles).

The seed crystal generation step S11 includes a first seed crystal generation step S111 in which the generation of nuclei and the formation of aggregates occur, and a second seed crystal generation step in which an outer shell is formed on the surface of the aggregates to generate seed crystal particles. Includes S112. In the present embodiment, by controlling the pH value and the like of the reaction aqueous solution in the stirring tank, the first kind crystal generation step S111 and the second kind crystal generation step S112 can be carried out separately.

Hereinafter, the first type crystal generation step S111 and the second type crystal generation step S112 will be described.

(Type 1 crystal generation step S111)
A raw material solution, a complexing agent and a neutralizing agent are mixed in a stirring tank to prepare a reaction aqueous solution.

First, a raw material liquid is prepared. The raw material liquid contains at least a metal salt containing a nickel salt. As the nickel salt, a sulfate, a nitrate, a hydrochloride or the like containing Ni is used. As the metal salt other than the nickel salt, a sulfate, a nitrate, a hydrochloride or the like containing Co, Al, Mn, Ti, V, Cr, Zr, Nb, Mo, Hf, Ta or W and the like is used. As the metal salt other than the nickel salt, one kind of salt containing various metals other than Ni mentioned above may be used alone, or two or more kinds may be used.

It is assumed that the nickel-containing hydroxide is a nickel composite hydroxide further containing a metal other than Ni. In this case, the metal composition ratio of the raw material liquid (for example, Ni: Co: Al or Ni: Co: Mn: M) is maintained even in the obtained nickel composite hydroxide, and thus is required for the nickel composite hydroxide. It is adjusted to match the composition ratio to be made.

A complexing agent, a neutralizing agent and water are supplied into the stirring tank and mixed. The aqueous solution in which these are mixed is hereinafter referred to as "pre-reaction aqueous solution".

As the complexing agent, an aqueous solution containing an ammonium ion feeder that combines with a metal ion such as nickel ion to form a complex such as a nickel ammine complex in the aqueous solution in the stirring tank can be used. As the complexing agent, an aqueous solution containing ammonia (ammonia water) or the like can be used as the ammonium ion feeder.

The neutralizing agent may be any one that reacts with a metal salt or a complex formed from the metal salt to form a metal hydroxide. The neutralizer is also used as a pH adjuster for adjusting the pH of the aqueous solution. As the neutralizing agent, an alkaline aqueous solution containing sodium hydroxide, potassium hydroxide and the like is used.

The pH value of the pre-reaction aqueous solution is preferably adjusted to 12.0 to 14.0, more preferably 12.3 to 13.5, and 12.6 to 13. It is more preferable to adjust to 1. The pH value of the pre-reaction aqueous solution can be measured with a known pH meter.

After adjusting the pH value of the pre-reaction aqueous solution in the stirring tank, the raw material liquid is supplied into the stirring tank while stirring the pre-reaction aqueous solution. As a result, a reaction aqueous solution in which the pre-reaction aqueous solution and the raw material solution are mixed is formed in the stirring tank.

When the raw material solution is reacted with the complexing agent and the neutralizing agent in the reaction aqueous solution, solute components (molecules) of nickel-containing hydroxide are generated in the reaction aqueous solution by neutralization crystallization.

In the first kind crystal generation step S111, when the solute component of the nickel-containing hydroxide produced by neutralization crystallization precipitates as a solid component in the reaction aqueous solution, it is generated as nuclear particles composed of nickel-containing hydroxide. However, agglomerates composed of a plurality of nuclear particles are generated in the reaction aqueous solution.

FIG. 2 is a diagram schematically showing an example of aggregates produced in the first kind crystal generation step S111. As shown in FIG. 2, in the first kind crystal generation step S111, the solute component of the nickel-containing hydroxide produced by neutralization crystallization is generated as the nuclear particles 110 made of nickel-containing hydroxide in the reaction aqueous solution. do. The solute component of the nickel-containing hydroxide generated in the reaction aqueous solution is deposited on the surface of the nuclear particle 110 as a solid component, so that the nuclear particle 110 grows. When the nuclear particles 110 grow and become large to some extent, they become primary particles 111, and the primary particles 111 collide with each other. When a plurality of primary particles 111 collide with each other, the primary particles 111 adhere to each other and aggregate. The aggregate 112 is generated by aggregating the plurality of primary particles 111.

When the agglomerate 112 is generated, the solute component of the nickel-containing hydroxide is precipitated on the surface of the agglomerate 112, and a precipitation layer is formed. As a result, the primary particles 111 constituting the aggregate 112 are chemically bonded to each other, and the bonding force between the primary particles 111 is strengthened.

The particle size of the aggregate can be obtained from the radius of the aggregate calculated by using the formula (I) described later. Details will be described later.

The pH value of the reaction aqueous solution is adjusted so as to be maintained within the same range as the pH value of the pre-reaction aqueous solution.

When the pH value of the reaction aqueous solution is 12.0 or more in the first kind crystal formation step S111, the generation of nuclei and the formation of aggregates are the precipitation of the solute component of the nickel-containing hydroxide on the surface of the aggregates. It becomes more dominant, and the generation of nuclei and the formation of aggregates mainly occur. When the pH value of the reaction aqueous solution is 14.0 or less in the first kind crystal generation step S111, it is possible to prevent the nuclear particles from becoming too fine and to prevent the reaction aqueous solution from gelling. In the first kind crystal generation step S111, the fluctuation range (the range between the maximum value and the minimum value) of the pH value of the reaction aqueous solution is preferably 0.4 or less.

In the first kind crystal generation step S111, a complexing agent or a neutralizing agent is supplied into the stirring tank in addition to the raw material liquid so that the pH value of the reaction aqueous solution is maintained within the above range. As a result, the pH value of the reaction aqueous solution is maintained within the above range, so that the generation of nuclei and the formation of aggregates are continued in the reaction aqueous solution.

The atmosphere in the stirring tank in the first kind crystal generation step S111 may be either an oxidizing atmosphere or a non-oxidizing atmosphere. When the atmosphere in the stirring tank is an oxidizing atmosphere, the oxygen concentration in the oxidizing atmosphere in the stirring tank is controlled by supplying oxygen gas, air, or the like to the reaction aqueous solution. When the atmosphere in the stirring tank is a non-oxidizing atmosphere, the oxygen concentration in the non-oxidizing atmosphere can be controlled by mixing an inert gas such as nitrogen or argon into the reaction aqueous solution.

The first kind crystal generation step S111 ends when a predetermined amount of agglomerates are generated. Whether or not a predetermined amount of agglomerates are produced can be estimated from the supply amount of the metal salt.

(Type 2 crystal generation step S112)
In the second kind crystal generation step S112, the pH value of the reaction aqueous solution in the stirring tank is adjusted to be lower than the pH value in the first kind crystal generation step S111. To adjust the pH value of the reaction aqueous solution, stop the supply of the complexing agent or neutralizing agent into the stirring tank, or use an inorganic acid in which the metal of the metal salt is replaced with hydrogen (for example, sulfuric acid in the case of sulfate). Can be carried out by supplying the above into a stirring tank or the like.

After adjusting the pH value of the reaction aqueous solution, the raw material liquid is supplied into the stirring tank while stirring the reaction aqueous solution. FIG. 3 is a cross-sectional view schematically showing an example of seed crystal particles formed in the second seed crystal generation step S112. As shown in FIG. 3, in the second kind crystal generation step S112, the solute component of the nickel-containing hydroxide generated in the reaction aqueous solution by neutralization crystallization precipitates on the surface of the aggregate 112 as a solid component (nickel-containing). Surface precipitation of solute components of hydroxides). As a result, the outer shell 113 is formed on the surface of the aggregate 112. As a result, the seed crystal particles 11 composed of the aggregate 112 and the outer shell 113 are obtained.

The pH value of the reaction aqueous solution in the stirring tank is preferably adjusted to 10.5 to 12.0, more preferably 10.7 to 11.7, based on the liquid temperature of 25 ° C., 11.0. It is more preferable to adjust to ~ 11.5.

If the pH value of the reaction aqueous solution is 12.0 or less in the second kind crystal formation step S112 and lower than the pH value of the reaction aqueous solution in the first kind crystal formation step S111, it is more than the generation of nuclei and the formation of aggregates. The surface precipitation of the solute component of the nickel-containing hydroxide is preferentially generated, and the generation of new nuclei and the formation of aggregates hardly occur.

In the second type crystal formation step S112, if the pH value of the reaction aqueous solution is 10.5 or more, the stability of the nickel ammine complex produced by the reaction between the nickel salt and the complexing agent is low, so that nickel-containing water is used. Metal ions that remain in the liquid without forming oxides are reduced, improving production efficiency.

In order to clearly separate the generation of nuclei and the formation of aggregates from the surface precipitation of solute components of nickel-containing hydroxides, the pH value of the reaction aqueous solution in the second kind crystal formation step S112 is used to generate the first kind crystal. It is preferably 0.5 or more lower than the pH value of the reaction aqueous solution in step S111, and more preferably 1.0 or more.

When the pH value of the reaction aqueous solution is 12.0, it is a boundary condition between the generation of nuclei and the formation of aggregates and the surface precipitation of the solute component of the nickel-containing hydroxide. Therefore, the priority order changes depending on the presence or absence of nuclei and aggregates present in the reaction aqueous solution.

For example, in the first kind crystal generation step S111, the pH value of the reaction aqueous solution is made higher than 12.0, a large amount of nuclei are generated in the reaction aqueous solution to generate aggregates, and then in the second kind crystal generation step S112. It is assumed that the pH value of the reaction aqueous solution is adjusted to 12.0. In this case, since a large amount of nuclei and aggregates are present in the reaction aqueous solution, surface precipitation of the solute component of the nickel-containing hydroxide is prioritized in the second kind crystal generation step S112.

On the other hand, when the reaction aqueous solution does not have nuclei or aggregates, that is, when the pH value of the reaction aqueous solution is set to 12.0 in the first type crystal formation step S111, the solute of the nickel-containing hydroxide in the reaction aqueous solution. There are no aggregates from which the components precipitate. Therefore, in this case, the generation of nuclei and the formation of aggregates take precedence over the surface precipitation of the solute component of the nickel-containing hydroxide. After that, if the pH value of the reaction aqueous solution is made smaller than 12.0 in the second kind crystal generation step S112, the solute component of the nickel-containing hydroxide is precipitated on the surface of the produced aggregate, and the outer shell grows.

In the second kind crystal generation step S112, a complexing agent or a neutralizing agent is supplied into the stirring tank in addition to the raw material liquid so that the pH value of the reaction aqueous solution is maintained within the above range. As a result, in the reaction aqueous solution, the solute component of the nickel-containing hydroxide present in the reaction aqueous solution is deposited on the surface of the aggregate, and the outer shell grows.

The pH value range of the reaction aqueous solution in the stirring tank in the second kind crystal generation step S112 is different from that in the reaction aqueous solution in the stirring tank in the first kind crystal forming step S111, but other conditions and the like may be substantially the same. .. As another condition, for example, the atmosphere in the stirring tank in the second kind crystal forming step S112 may be either an oxidizing atmosphere or a non-oxidizing atmosphere as in the first kind crystal forming step S111.

When the seed crystal particles have grown to a predetermined particle size, the second seed crystal generation step S112 is terminated. The particle size of the seed crystal particles can be estimated from the supply amount of the metal salt in each of the first seed crystal generation step S111 and the second seed crystal generation step S112.

In the middle of the second kind crystal generation step S112, the supply of the raw material liquid and the like may be stopped, the stirring of the reaction aqueous solution may be stopped, the seed crystal particles may be settled, and then the supernatant liquid may be discharged. As a result, the metal ion concentration in the reaction aqueous solution reduced by neutralization crystallization can be increased.

In the seed crystal generation step S11, by separately performing the first seed crystal generation step S111 and the second seed crystal generation step S112, it is possible to generate seed crystal particles having a narrow particle size distribution range.

In this embodiment, the first type crystal generation step S111 and the second type crystal generation step S112 are performed in the same stirring tank, but may be performed in different stirring tanks.

In the present embodiment, the seed crystal generation step S11 uses a batch type stirring tank, but a continuous type stirring tank may be used. In this case, the first kind crystal generation step S111 and the second kind crystal generation step S112 are carried out at the same time. Therefore, since the range of the pH value of the aqueous solution in the stirring tank is the same, the pH value of the aqueous solution in the stirring tank is set to, for example, in the vicinity of 12.0.

In the present embodiment, the structure of the seed crystal particles obtained in the seed crystal generation step S11 is not limited to the structure shown in FIG. For example, when the first seed crystal generation step S111 and the second seed crystal generation step S112 are carried out at the same time, the structure of the seed crystal particles obtained at the completion of the seed crystal generation step S11 is that of the seed crystal particles shown in FIG. It is different from the structure. The structure is, for example, a mixture of those corresponding to the primary particles 111 and those corresponding to the outer shell 113, and becomes a uniform structure in which the boundary is not easily known.

[Growth crystallization step S12]
As shown in FIG. 1, after the seed crystal generation step S11 is completed, the growth crystallization step S12 is performed. The growth crystallization step S12 can be performed in the same manner as the conditions of the above-mentioned second type crystal generation step S112. That is, in the growth crystallization step S12, the pH value of the reaction aqueous solution in the stirring tank is the same as that of the above-mentioned type 2 crystal generation step S112.

In the growth crystallization step S12, the atmosphere in the stirring tank may be either an oxidizing atmosphere or a non-oxidizing atmosphere, as in the first type crystal forming step S111 and the second kind crystal forming step S112.

In the growth crystallization step S12, the solute component of the nickel-containing hydroxide is deposited on the surface of the seed crystal particles generated in the seed crystal generation step S11. FIG. 4 is a cross-sectional view schematically showing the particles of the nickel-containing hydroxide produced in the growth crystallization step S12. As shown in FIG. 4, in the growth crystallization step S12, the solute component of the nickel-containing hydroxide is deposited on the surface of the seed crystal particles 11 to form the outer shell portion 12. As a result, the nickel-containing hydroxide particles 10 composed of the seed crystal particles 11 and the outer shell portion 12 are obtained.

The growth crystallization step S12 ends when the nickel-containing hydroxide particles grow to a predetermined particle size. The particle size of the nickel-containing hydroxide particles can be estimated from the supply amount of the metal salt in each of the seed crystal forming step S11 and the growth crystallization step S12.

After the completion of the growth crystallization step S12, the obtained nickel-containing hydroxide particles are recovered by overflowing the reaction aqueous solution of the stirring tank or discharging it from the bottom of the stirring tank.

The growth crystallization step S12 may be continued as it is in the stirring tank used in the above-mentioned seed crystal forming step S11, or after the completion of the above-mentioned seed crystal forming step S11, the reaction aqueous solution in the stirring tank may be continued. May be transferred to another stirring tank (liquid transfer). When the growth crystallization step S12 is performed in a stirring tank different from the stirring tank used in the above-mentioned seed crystal generation step S11, the size of the stirring tank used in the growth crystallization step S12 is the seed crystal generation step. It may be the same size as the stirring tank used in S11, or may be larger than the stirring tank used in the seed crystal generation step S11.

In the middle of the growth crystallization step S12, the supply of the raw material liquid or the like may be stopped and the stirring of the reaction aqueous solution may be stopped to settle the nickel-containing hydroxide particles, and then the supernatant liquid may be discharged. .. As a result, the metal ion concentration in the reaction aqueous solution reduced by neutralization crystallization can be increased. Further, it is assumed that the growth crystallization step S12 is performed in a stirring tank different from the stirring tank used in the above-mentioned seed crystal generation step S11. In this case, in the second kind crystal generation step S112, the supply of the raw material liquid and the like is stopped and the stirring of the reaction aqueous solution is stopped, and the second kind crystal generation step S112 is terminated. Then, before transferring the reaction aqueous solution in the stirring tank to another stirring tank, the particles of the nickel-containing hydroxide may be settled and then the supernatant liquid may be discharged.

In the present embodiment, the growth crystallization step S12 is performed to precipitate the solute component of the nickel-containing hydroxide on the surface of the seed crystal particles 11 to form the outer shell portion, but the average particle size of the seed crystal particles 11 is formed. If is sufficient, the growth crystallization step S12 does not necessarily have to be performed. In this case, the seed crystal particles obtained in the seed crystal generation step S11 are used as nickel-containing hydroxide particles.

(Chemical reactor)
An example of a chemical reaction apparatus used in the method for producing a nickel-containing hydroxide according to an embodiment will be described. FIG. 5 is a top view showing a chemical reaction apparatus used in the method for producing a nickel-containing hydroxide according to an embodiment. FIG. 6 is a cross-sectional view of the chemical reaction apparatus along the line I-I of FIG. As shown in FIGS. 5 and 6, the chemical reaction apparatus 20 includes a stirring tank 21, a stirring shaft 22, a stirring blade (disk turbine blade (DT blade)) 23, a baffle (obstacle plate) 24, and a raw material liquid. It has a supply pipe 25, a neutralizing agent supply pipe 26, and a complexing agent supply pipe 27.

The stirring tank 21 accommodates the reaction aqueous solution in a columnar internal space. The stirring shaft 22 is inserted into the stirring tank 21 from the upper part of the stirring tank 21, and the upper end of the stirring shaft 22 is rotatably supported by a drive device such as a motor provided above the stirring tank 10. A stirring blade 23 is attached to the lower end of the stirring shaft 22. When the motor or the like rotates the stirring shaft 22, the stirring blade 23 is rotated, and the reaction aqueous solution in the stirring tank 21 is stirred by the stirring blade 23. The center line of the stirring tank 21, the center line of the stirring shaft 22, and the center line of the stirring blade 23 may be the same or may be vertical.

The baffle 24 protrudes from the inner peripheral surface of the stirring tank 21. The baffle 24 interferes with the rotational flow of the reaction aqueous solution in the stirring tank 21 to generate an ascending flow and a descending flow in the stirring tank 21 to improve the stirring efficiency of the reaction aqueous solution.

The raw material liquid supply pipe 25 supplies the raw material liquid into the stirring tank 21 from the addition port 251. The neutralizing agent supply pipe 26 supplies the neutralizing agent into the stirring tank 21 from the addition port 261. The complexing agent supply pipe 27 supplies the complexing agent into the stirring tank 21. In the seed crystal generation step S11 and the growth crystallization step S12, when the raw material liquid is added to the reaction aqueous solution from the addition port 251 of the raw material liquid supply pipe 25, the metal salt and the neutralizing agent and the complexion added to the reaction aqueous solution are added. Reacts with the agent. As a result, a solute component of the nickel-containing hydroxide is generated in the reaction aqueous solution.

(Calculation of average particle size of aggregates in type 1 crystal generation step S111)
By the way, the size of the particles of the nickel-containing hydroxide finally obtained tends to depend on the size of the agglomerates produced in the first kind crystal forming step S111. Seed crystal particles are obtained by forming an outer shell on the surface of the agglomerate in the second seed crystal forming step S112, and nickel-containing water is obtained by forming an outer shell portion on the surface of the seed crystal particles in the growth crystallization step S12. Oxide particles are obtained. In the first kind crystal forming step S111, the number density of the agglomerates contained in the reaction aqueous solution is determined from the supply amount of the raw material liquid in the first kind crystal forming step S111 and the size of the agglomerates. The specific surface area of the aggregate can be specified from the size and number density of the aggregate. If the supply amount of the raw material liquid in the second kind crystal generation step S112 and the growth crystallization step S12 is determined, the thickness of the outer shell and the outer shell portion deposited on the surface of the agglomerate generated in the first kind crystal generation step S111. Is decided. The present inventor can adjust the size of the seed crystal particles produced in the second seed crystal generation step S112 by adjusting the size of the aggregate, and finally adjust the size of the nickel-containing hydroxide particles. I noticed that it can be adjusted. Therefore, the average particle size of the aggregates produced in the first type crystal generation step S111 is calculated in advance, and the conditions for the first type crystal generation step S111 are set. By adjusting the particle size of the agglomerates based on the conditions set in the first type crystal generation step S111 and producing an agglomerate having a predetermined average particle size, a predetermined type 2 crystal generation step S112 is performed. It has been found that seed crystal particles having an average particle size can be produced.

As the average particle size, for example, a volume average particle size can be used. As shown in the following formula (i), the volume average particle size is the sum of the diameters of individual particles multiplied by the volume of the particles divided by the total volume of the particles in the set of particles. The volume average particle size can be measured by, for example, a laser diffraction scattering method using a laser diffraction type particle size distribution meter.
Volume average particle size _MV = Σ (Vn × dn) / Σ (Vn) ・ ・ ・ (i)
(However, in formula (I), V is the volume of the particle, d is the particle size of the particle, and n is an integer of 1 or more.)

The average particle size of the agglomerates is the binding energy for binding the particles forming the agglomerates (for example, nuclear particles or agglomerates) and the binding energy for breaking the bonds between the particles (for example, nuclei particles or agglomerates). It can be said that it is determined by the balance of.

The binding energy is formed by forming a pair of particles (for example, nuclear particles and aggregates) in contact with each other in a highly supersaturated region by precipitating a solute component of a nickel-containing hydroxide on the surface of the pair of particles. It refers to the energy generated by binding in the precipitation layer.

The breaking energy is the energy required for a part of the particles (for example, an agglomerate) to be divided into a plurality of particles (for example, an agglomerate) when the particles pass through the stirring blade of the stirring tank. ..

The binding energy for binding particles (for example, nuclear particles and aggregates) forming aggregates and the binding energy for dividing the bonds between particles (for example, nuclear particles and aggregates) will be described.

First, the binding energy of particles (for example, nuclear particles and aggregates) will be described. The binding energy of particles is obtained by formulating and organizing each of the following four phenomena (A) to (D).

(A) The binding energy of the particles is the cross-sectional area of the bonding portion of the particle pair in which the aggregate (radius R [unit: μm]) and the nuclear particle (radius r [unit: μm]) are in contact with each other, as shown in FIG. It is proportional to S (unit: μm ² ).

FIG. 7 is an explanatory diagram showing an example of a model in which nuclear particles are aggregated in an aggregate. As shown in FIG. 7, it is assumed that the aggregate (radius R [unit: μm]) and the nuclear particle (radius r [unit: μm]) are in contact with each other. The aggregates and nuclear particles are considered to be chemically bonded in a precipitation layer (thickness Δh [unit: μm]) formed by precipitating solute components of nickel-containing hydroxide on their surfaces. When the bonding neck portion of the particle pair of the nuclear particle and the aggregate is divided, two new planes (cross-sectional area S) appear in these bonding portions. Since the binding energy of the particles is considered to correspond to the increase in the surface energy due to this new surface, the binding energy of the particles is proportional to the cross-sectional area S.

(B) The cross-sectional area S is formed by precipitating solute components of nickel-containing hydroxide on the surface of aggregates and nuclear particles in a region where the degree of supersaturation C (unit: mol / m ³ ) is from c to c + Δc. It is proportional to the thickness Δh of the deposited layer and the radius r of the nuclear particles. In addition, c means a predetermined value of supersaturation degree C, and Δc means the amount of change of c.

(C) The thickness Δh of the precipitation layer is the time (passing time) Δt (unit: s) for the particles (for example, aggregates) to pass through the region where the supersaturation degree C is from c to c + Δc, and the particles (for example, coagulation). Aggregate) It is proportional to the growth rate κ (unit: μm / s) due to the surface precipitation of the solute component of the nickel-containing hydroxide per particle. The transit time Δt is also referred to as reaction time, and the growth rate κ is also referred to as precipitation rate.

Here, the transit time Δt can be expressed by the following equation (1).

When the time scale for turbulent dispersion of the solute component of the nickel-containing hydroxide to a predetermined concentration is t _d (unit: s), the time scale t _d for turbulent dispersion is √ (ΔV / (uK). ) The above equation (1) can be obtained by using the following equation (2), which represents an approximation to _C ).

However, ΔV (unit: m ³ ) is the volume of the region where the hypersaturation degree C is from c to c + Δc, and (uK) _C is the average flow velocity u of the fluid passing through the region where the hypersaturation degree C is from c to c + Δc. It is a volume average (unit: m ³ / s ² ) of the product of (unit: m / s) and the turbulent flow diffusion coefficient K (unit: m ² / s) of the fluid flow. The volume average is a value obtained by dividing the integrated value obtained by volume-integrating uK in the region where the supersaturation degree C is from c to c + Δc by the volume in the region where the supersaturation degree C is from c to c + Δc.

The reason why the above formula (1) is obtained by using the above formula (2) is that the inertial force of the particles (nuclear and aggregate) is very small, so that the particles are disturbed in the region where the supersaturation degree C is from c to c + Δc. This is because it can be regarded as exercising almost following the flow of the flow.

In the turbulent flow dispersion time scale _dt of the above formula (2), when the raw material liquid is added to the reaction aqueous solution using N raw material liquid supply pipes 25 (see FIG. 5) of N lines (N: an integer of 2 or more), The region where the degree of supersaturation C is from c to c + Δc is divided into N pieces. Therefore, the transit time Δt of the volume in the region where the supersaturation degree C is from c to c + Δc can be expressed by the above equation (1).

(D) The growth rate κ is controlled by the molecular diffusion of the solute component of the nickel-containing hydroxide.

The growth rate κ due to surface precipitation of the solute component of the nickel-containing hydroxide per particle (for example, agglomerate) is that the solute component of the nickel-containing hydroxide present in the reaction aqueous solution precipitates on the surface of the agglomerate. You can refer to the precipitation reaction model. In this precipitation reaction model, the rate-determining process of the surface precipitation reaction is the molecular diffusion of the solute component of the nickel-containing hydroxide. Therefore, the growth rate κ of the precipitation layer is as shown in the following formula (3). Multiply the molecular diffusion coefficient D (unit: m ² / s) of the solute component of the oxide by the degree of supersaturation C to obtain the diffusion flux of the solute component of the nickel-containing hydroxide with the apparent density ρ _p of the precipitation layer and the aggregate. It can be obtained by dividing by the radius R.

By arranging the above four phenomena (A) to (D) using the formulas (1) to (3), the binding energy E _b (unit: J) of the particles is the following formula (4). It is expressed as.

However, A is a model coefficient related to binding energy in which constants such as physical property values are collectively expressed, and N is the number of addition ports of the raw material liquid. C _T represents the threshold value of the degree of supersaturation C. A region in which the degree of supersaturation C is equal to or higher than the threshold value C _T is referred to as a high supersaturation region. In this highly supersaturated region, it is considered that a precipitation layer appears due to the surface precipitation of the solute component of the nickel-containing hydroxide.

Here, the highly supersaturated region C _T will be described. FIG. 8 is a diagram showing a highly _{supersaturated} region CT formed in the vicinity of the addition port of the raw material liquid. In FIG. 8, the arrow direction indicates the direction of the flow of the reaction aqueous solution in the vicinity of the addition port 251 of the raw material liquid supply pipe 25 of the chemical reaction apparatus 20 shown in FIG. As shown in FIG. 8, the raw material liquid is added to the reaction aqueous solution from the addition port 251 of the raw material liquid supply pipe 25 shown in FIG. The metal salt in the raw material solution neutralizes with the neutralizing agent and the complexing agent near the addition port 251 to generate a solute component of the nickel-containing hydroxide, and nickel is contained in the reaction aqueous solution near the addition port 251. A highly hypersaturated region 31 having a high molar concentration of the contained hydroxide is formed.

In the first seed crystal generation step S111 of the seed crystal generation step S11, the generation of nuclei and the formation of aggregates mainly occur in the highly supersaturated region 31. In the first kind crystal generation step S111, in the highly supersaturated region 31, when the solute component of the nickel-containing hydroxide produced in the reaction aqueous solution is precipitated in the reaction aqueous solution, it is generated as nuclear particles. The nuclear particles grow to some extent while passing through the highly supersaturated region 31, and become primary particles. Then, a plurality of primary particles are aggregated to form an aggregate.

In FIG. 8, in the first kind crystal generation step S111, the raw material liquid is discharged from one addition port 251 into the reaction aqueous solution, and the number of highly supersaturated regions 31 is one, but a plurality of addition ports 251 The raw material liquid may be separated from the above and discharged into the reaction aqueous solution to have a plurality of highly supersaturated regions 31. When the number of the high supersaturation regions 31 is plural, the volume of the high supersaturation regions 31 means the total volume of the plurality of regions. At this time, the intervals between the plurality of addition ports 251 are set so that the plurality of highly supersaturated regions 31 discharged from the plurality of addition ports 251 do not overlap.

Next, the breaking energy of particles (for example, nuclear particles and aggregates) will be described. The fragmentation energy of particles is obtained by formulating and arranging each of the following four phenomena (a) to (d).

(A) The dividing energy of particles is representative of the acceleration (unit: m / s ² ) when the particles (for example, aggregates) pass through the stirring blade and the distance at which the particles (for example, aggregates) are accelerated. It is proportional to the length (unit: m).
(B) As the representative length, the stirring blade diameter L _p (unit: m) is used.

In the stirring tank shown in FIG. 6, the flow of the reaction aqueous solution stirred by the stirring blade reaches the liquid surface from the bottom of the tank along the side wall, changes the direction of the flow to the stirring shaft at the liquid level, and then turns the stirring shaft. It flows down from the periphery of the agitator and is swallowed by the stirring blade. In this circulating flow, the flow of the reaction aqueous solution is accelerated by receiving a force as it passes through the stirring blade. At this time, at the same time, the particles (for example, aggregates) are also accelerated by receiving a force from the stirring blade. Considering that a part of this acts as a force to break the bond of particles (for example, agglomerates), the breaking energy of particles (for example, agglomerates) is proportional to the acceleration of the particles and the stirring blade diameter _Lp .

(C) The acceleration of the particles is dimensionally analyzed by the stirring blade diameter _Lp , which is the representative length, and the rotation speed ω (unit: s ^-1 ) of the stirring blade.

The acceleration that particles (eg, aggregates) receive as they pass through the stirring blade depends on the specifications and operating conditions of the stirring blade. The acceleration at which particles (for example, aggregates) are accelerated in the flow direction is obtained by multiplying the stirring blade diameter _Lp by the square of the rotation speed ω of the stirring blade.

(D) The breaking energy of the particles is proportional to the weight of the agglomerates.

Since the weight of the aggregate is proportional to the volume of the aggregate, it is proportional to the value R ³ which is the cube of the radius R of the aggregate. Assuming that the particles are a pair of particles in which an aggregate and a nucleus particle are bonded (see FIG. 7), a value R ³ obtained by cubed the radius R of the aggregate and a value r ³ obtained by cubed the radius r of the nucleus particle. By using the sum of and (R ³ + r ³ ), the volume of the particles can be obtained. At this time, since it can be said that the aggregate is sufficiently larger than the nuclear particle, it can be considered that R ³ + r ³ is close to R ³ (R ³ + r ³ ≈ R ³ ). Therefore, the fragmentation energy of the particles can be treated as being proportional to the weight of the aggregate.

By arranging the above four phenomena (a) to ( _d ), the breaking energy Ek (unit: J) of particles (for example, aggregates) is expressed by the following formula (5).

However, B is a model coefficient related to the dividing energy, in which constants such as physical property values are collectively expressed. As described above, R ³ is an index showing the weight of the particles. (Ω ・ L _p ) ² is an index showing the square of the velocity of the particle.

In the particle size growth model in which a plurality of nuclei aggregate to form an aggregate, it can be said that the radius R of the aggregate is determined by the balance between the binding energy E _b and the split energy E _k , as described above. That is, since the binding energy E _b and the breaking energy E _k depend on the particle size of the aggregate, the binding energy E _b becomes larger and the breaking energy E _k becomes smaller as the aggregate becomes larger. Can be thought of. Therefore, when the size of the agglomerates becomes a certain size, the binding energy E _b and the breaking energy E _k become equal to each other, and the growth of the agglomerates is settled at a size in which the binding energy E _b and the breaking energy E _k are balanced. I will go.

Therefore, if the above equation (4) representing the binding energy E _b and the above equation (5) representing the dividing energy E _k are connected by an equation and the radius R of the aggregate is arranged, the following equation (I) is obtained. Be done.

In the above formula (I), the radius r of the nuclear particle is 0.3 μm from the experimental result. Further, A and B are model coefficients as described above, and are treated as constants.

The supersaturation degree C in the high supersaturation region (see FIG. 8), the volume ΔV in the region where the supersaturation degree C is from c to c + Δc, and the turbulent flow dispersion parameter uK can be obtained by fluid reaction simulation using general-purpose fluid analysis software. .. The u (unit: m / s) of uK is the average flow velocity of the fluid passing through the highly supersaturated region, and K (unit: m ² / s) is the turbulent diffusivity of the fluid flowing through the highly supersaturated region. Is. Specifically, the calculation method using the fluid reaction simulation can be performed according to the method described in International Publication No. 2017/217365 and the like.

From the above, the high supersaturation region is calculated by the fluid reaction simulation, and the supersaturation degree C in the high supersaturation region, the volume ΔV in the region where the supersaturation degree C is from c to c + Δc, and the turbulence dispersion parameter uK are acquired. Then, by substituting these acquired numerical values, the number N of multipoint additions, the blade diameter _Lp and the rotation speed ω of the stirring blade (DT blade) into the above equation (I), the first type crystal The radius R of the aggregate in the generation step S111 can be obtained. This makes it possible to determine the average particle size of the aggregates.

Therefore, according to the present embodiment, by using the above formula (I), the average particle size of the aggregate produced in the first kind crystal generation step S111 can be obtained in advance, so that the first kind crystal generation step The production conditions of S111 can be set so that an aggregate having a predetermined average particle size can be obtained. The manufacturing conditions include, for example, the capacity and shape of the stirring tank, the model, rotation speed, number, shape, dimensions or installation location of the stirring blade, the rotation speed of the stirring blade, the pH value or temperature of the reaction aqueous solution, the flow rate of the raw material liquid, and the like. The concentration, the position, shape, number, arrangement method, etc. of the addition port of the raw material liquid supply pipe can be mentioned. By performing the first type crystal generation step S111 based on the production conditions set in the first type crystal generation step S111, the average particle size of the agglomerates generated in the first type crystal generation step S111 can be adjusted with high accuracy. ..

By generating agglomerates having a predetermined average particle size in the first kind crystal generation step with high accuracy, it is possible to generate seed crystal particles having a predetermined average particle size produced in the second kind crystal generation step with high accuracy. .. When producing nickel-containing hydroxide particles in the growth crystallization step after the seed crystal forming step, by using the seed crystal particles generated in the seed crystal forming step, aggregates having a predetermined average particle size can be stably produced. Can be generated.

The method for producing a nickel-containing hydroxide may include a step of confirming the average particle size of the aggregate in the seed crystal forming step. This confirmation may be performed each time the above-mentioned manufacturing conditions are changed. Further, when the stirring tank is a batch type, the confirmation may be performed once while the manufacturing conditions are the same, and the confirmation does not need to be performed each time.

As described above, the nickel-containing hydroxide particles produced by using the method for producing a nickel-containing hydroxide according to the embodiment are precursors of a lithium nickel composite oxide used as a positive electrode active material for a lithium ion secondary battery. It can be used as a body. The positive electrode active material produced by using the precursor can be used in the production of the positive electrode. The obtained positive electrode can be effectively used for a lithium ion secondary battery.

Lithium-ion secondary batteries can be charged and discharged from mobile information terminals such as mobile phones, smartphones, tablet PCs or notebook PCs, portable music players, digital cameras, medical devices, HEVs, or clean energy vehicles such as EVs or PHEVs. Can be suitably used as a battery.

<Preliminary test>
In order to calculate the average particle size of the aggregates obtained in the type 1 crystal formation step using the above formula (I), first, a preliminary test for calculating the model coefficients A and B in the above formula (I) is performed. went. The type 1 crystal generation step refers to the type 1 crystal generation step S111 shown in FIG. 1 above.

[Preparation of aggregates]
(Preliminary test 1)
Using an overflow-type continuous stirring tank, a first-class crystal formation step of forming an agglomerate made of a nickel composite hydroxide was carried out by neutralization crystallization. The volume of the stirring tank was 50 L, the type of the stirring blade was a disc turbine blade, the number of blades of the stirring blade was 6, the blade diameter of the stirring blade was 150 mm, and the rotation speed of the stirring blade was 600 rpm. The initial liquid volume of the stirring tank before the start of the reaction was 10 L, and the liquid volume of the reaction aqueous solution of the stirring tank at the time when the first type crystal formation step was completed was 15 L. After that, the amount of the reaction aqueous solution in the stirring tank at the time when the reaction of the second kind crystal generation step was completed was 50 L. The temperature of the reaction aqueous solution was maintained at 40 ° C. The atmosphere in the stirring tank was an oxygen atmosphere.

The raw material solution was prepared so that Ni _0.34 Mn _0.33 Co _0.33 (OH) ₂ could be obtained as a nickel composite hydroxide. The number of raw material liquid supply pipes was two, the supply amount from the two raw material liquid supply pipes was 100 mL / min, and the flow rate ratio of the raw material liquid in the first type crystal forming step was 0.77. The flow rate ratio of the raw material liquid in the type 1 crystal forming step is the ratio of the average flow rate of the raw material liquid to the average flow rate of the raw material liquid under the reference condition when the average flow rate of the reference condition is 1.0. The reference condition refers to the flow rate of the raw material liquid when an agglomerate having an average particle size within a predetermined range is obtained.

During the first type crystal formation step, in addition to the raw material solution, sodium hydroxide aqueous solution as a neutralizing agent and ammonia water as a complexing agent were supplied into the stirring tank to maintain the pH value of the reaction aqueous solution and the like.

The reaction aqueous solution in the stirring tank was sampled, and the average particle size of the aggregates contained in the sampled reaction solution was measured with a laser diffraction type particle size distribution measuring device (Microtrac Bell Co., Ltd.). The average particle size of the obtained aggregate was about 3.20 μm.

(Preliminary test 2)
Aggregates were produced in the same manner as in Preliminary Test 1 except that the number of raw material liquid supply pipes was changed to 4 in Preliminary Test 1. The average particle size of the obtained aggregate was about 3.00 μm.

[Calculation of model coefficients A and B]
Based on the test conditions and test results of the preliminary tests 1 and 2, the above formula (experimental value) is such that the value (calculated value) of the average particle size of the obtained aggregate is the value (experimental value) obtained in the preliminary tests 1 and 2. The model coefficients A and B in I) were calculated.

<Example 1>
(Calculation of average particle size of aggregates)
Using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the aggregate obtained in the first kind crystal generation step S111 was calculated in advance as 2.95 μm.
(Preparation of aggregate)
In the preliminary test 1, the aggregate was produced in the same manner as in the preliminary test 1 except that the rotation speed of the stirring blade was changed to 1.11 times the rotation speed of the stirring blade in the preliminary test 1. The average particle size of the obtained aggregate was about 2.70 μm.

The absolute value of the error of the experimental value (2.70 μm) with respect to the calculated value (2.95 μm) of the average particle size of the aggregate was about 8.5% from the following formula.
Error (%) = | (Experimental value-Calculated value) / Calculated value x 100 |

<Example 2>
In Example 1, using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the agglomerates obtained in advance in the type 1 crystal formation step was set to 3.25 μm. Calculated. Then, an aggregate was produced in the same manner as in Example 1 except that the flow rate ratio of the raw material liquid in the first type crystal generation step was changed to about 1.54. The average particle size of the obtained aggregate was about 3.05 μm. The absolute value of the error of the experimental value (3.05 μm) with respect to the calculated value (3.25 μm) of the average particle size of the aggregate was about 6.2%.

<Example 3>
In Example 1, using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the agglomerates obtained in advance in the type 1 crystal formation step was set to 4.50 μm. Calculated. Then, the flow ratio of the raw material liquid in the first type crystal generation step was changed to about 1.54, the number of raw material liquid supply pipes was changed to 4, and the rotation speed of the stirring blade was changed to the rotation of the stirring blade in the preliminary test 1. Aggregates were produced in the same manner as in Example 1 except that the number was changed to about 0.68 times. The average particle size of the obtained aggregate was about 4.75 μm. The absolute value of the error of the experimental value (4.75 μm) with respect to the calculated value (4.50 μm) of the average particle size of the aggregate was about 5.3%.

<Example 4>
In Example 1, using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the agglomerates obtained in advance in the type 1 crystal formation step was set to 3.35 μm. Calculated. Then, the flow ratio of the raw material liquid in the first type crystal generation step was changed to 1.54, the number of raw material liquid supply pipes was changed to 4, and the rotation speed of the stirring blade was changed to the rotation speed of the stirring blade in the preliminary test 1. Aggregates were produced in the same manner as in Example 1 except that the amount was changed to 1.00 times. The average particle size of the obtained aggregate was about 3.55 μm. The absolute value of the error of the experimental value (3.55 μm) with respect to the calculated value (3.30 μm) of the average particle size of the aggregate was about 6.0%.

<Example 5>
In Example 1, using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the agglomerates obtained in advance in the type 1 crystal formation step was set to 3.10 μm. Calculated. Then, in the preliminary test 1, the flow rate ratio of the raw material liquid in the first type crystal generation step was changed to 2.00, and the rotation speed of the stirring blade was about 1.16 times the rotation speed of the stirring blade in the preliminary test 1. Aggregates were produced in the same manner as in Example 1 except that the agglomerates were changed to. The average particle size of the obtained aggregate was about 3.25 μm. The absolute value of the error of the experimental value (3.25 μm) with respect to the calculated value (3.10 μm) of the average particle size of the aggregate was about 4.8%.

<Example 6>
In Example 1, using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the agglomerates obtained in advance in the type 1 crystal formation step was set to 4.15 μm. Calculated. Then, the flow rate ratio of the raw material liquid in the first type crystal generation step was changed to 1.33 times, the number of raw material liquid supply pipes was changed to one, and the rotation speed of the stirring blade was changed to the rotation of the stirring blade in the preliminary test 1. Aggregates were produced in the same manner as in Example 1 except that the number was changed to about 1.67 and the capacity of the stirring tank was changed to 0.10 times the capacity of the stirring tank used in the preliminary test 1. did. The average particle size of the obtained aggregate was about 4.05 μm. The absolute value of the error of the experimental value (4.05 μm) with respect to the calculated value (4.15 μm) of the average particle size of the aggregate was about 2.4%.

<Example 7>
In Example 1, using the above formula (I) and the model coefficients A and B calculated in the preliminary tests 1 and 2, the average particle size of the aggregate obtained in advance in the first type crystal formation step S111 is 3.55 μm. I calculated. Then, the flow ratio of the raw material liquid in the first type crystal generation step was changed to 1.33, the rotation speed of the stirring blade was changed to about 1.67 times the rotation speed of the stirring blade in the preliminary test 1, and stirring was performed. Aggregates were produced in the same manner as in Example 1 except that the capacity of the tank was changed to 0.10 times the capacity of the stirring tank used in the preliminary test 1. The average particle size of the obtained aggregate was about 3.27 μm. The absolute value of the error of the experimental value (3.27 μm) with respect to the calculated value (3.55 μm) of the average particle size of the aggregate was about 7.9%.

In each of the above preliminary tests and examples, the flow rate ratio of the raw material liquid in the first type crystal generation step, the number of addition ports of the raw material liquid, the rotation speed ratio of the stirring blade, and the capacity ratio of the stirring tank were calculated in advance. Table 1 shows the calculated value of the average particle size of the aggregate, the measured value of the average particle size of the produced aggregate, and the absolute value of the error of the experimental value with respect to the calculated value of the average particle size of the aggregate. Further, FIG. 9 shows the calculated value and the measured value of the average particle size of the aggregate in each of the above-mentioned examples. The rotation speed ratio of the stirring blade in the table is the ratio of the rotation speed of the stirring blade to the rotation speed of the stirring blade in the preliminary test 1. The capacity ratio of the stirring tank is the ratio of the capacity of the stirring tank to the capacity of the stirring tank in the preliminary test 1.

As shown in Table 1 and FIG. 9, in any of the examples, the size of the average particle size of the aggregate calculated in advance is 10% or less with respect to the size of the average particle size of the actually produced aggregate. It was an error.

Therefore, it was confirmed that by using the above formula (I), the average particle size can be adjusted with high accuracy in the first kind crystal generation step S111 to produce an aggregate. By adjusting the average particle size of the aggregates produced in the first type crystal generation step with high accuracy, the average particle size of the seed crystal particles produced in the second type crystal generation step can be adjusted with high accuracy. In addition, the average particle size of the nickel-containing hydroxide particles finally obtained in the growth crystallization step after the seed crystal forming step can be adjusted with high accuracy.

As described above, the embodiments have been described, but the above embodiments are presented as examples, and the present invention is not limited to the above embodiments. The above embodiment can be implemented in various other embodiments, and various combinations, omissions, replacements, changes, etc. can be made without departing from the gist of the invention. These embodiments and variations thereof are included in the scope and gist of the invention, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

10 Nickel-containing hydroxide particles 11 Seed crystal particles 110 Nuclei (nuclear particles)
111 Primary particles 112 Aggregates 113 Outer shell 12 Outer shell part 20 Chemical reactor 21 Stirring tank 23 Stirring blade 25 Raw material liquid supply pipe 251 Addition port 31 Highly supersaturated region

Claims (4)

A raw material solution containing a metal salt containing at least a nickel salt, a complexing agent that combines with a metal ion of the metal salt to form a complex, and the metal salt and the complex to form a metal hydroxide. A method for producing a nickel-containing hydroxide, which obtains a nickel-containing hydroxide by neutralization crystallization in a reaction aqueous solution containing a neutralizing agent.
In the reaction aqueous solution, a seed crystal generation step of growing the nucleus of the nickel-containing hydroxide generated by neutralization crystallization to generate a seed crystal is included.
The seed crystal forming step is a first kind crystal forming step in which the nuclei of the nickel-containing hydroxide are generated by neutralization crystallization in the reaction aqueous solution to form an agglomerate in which a plurality of the nuclei are aggregated. Including,
A method for producing a nickel-containing hydroxide, wherein the first-class crystal forming step is carried out under the conditions set based on the following formula (I).

(However, in equation (I), R is the radius of the aggregate, A is the model coefficient, r is the radius of the nucleus, _C is the degree of supersaturation, and CT is the threshold of the degree of supersaturation C. , N is the number of addition ports of the raw material liquid, ΔV is the volume of the region where the supersaturation degree C is from c to c + Δc, and u is the average flow velocity of the fluid passing through the region where the supersaturation degree C is from c to c + Δc. Yes, K is the turbulent diffusion coefficient of the flow of fluid passing through the region where the supersaturation degree C passes from c to c + Δc, B is the model coefficient, ω is the rotation speed of the stirring blade, and L _p is the stirring blade. The wing diameter of.) The nickel-containing hydroxide contains Ni, Co, Mn, and M (M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W). Material amount ratio is Ni: Co: Mn: M = x: y: z: t (however, x + y + z + t = 1, 0.1 ≦ x ≦ 0.9, 0.1 ≦ y ≦ 0.5, 0.1 ≦ The method for producing a nickel-containing hydroxide according to claim 1, which comprises z ≦ 0.8 and 0 ≦ t ≦ 0.02). The nickel-containing hydroxide is Ni, Co, and Al, and the substance amount ratio is Ni: Co: Al = 1-xy: x: y (however, 0 ≦ x ≦ 0.3, 0.005 ≦). The method for producing a nickel-containing hydroxide according to claim 1, which comprises y ≦ 0.15). A method for producing a nickel-containing hydroxide using the nickel-containing hydroxide according to any one of claims 1 to 3 as a precursor of a positive electrode active material of a non-aqueous electrolyte secondary battery.

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