JP6954111B2 - Method for producing nickel-containing hydroxide - Google Patents

Description

The present invention relates to a method for producing a nickel-containing hydroxide used as a precursor of a positive electrode active material of a lithium ion secondary battery.

In recent years, with the spread of portable electronic devices such as mobile phones and notebook personal computers, there is a demand for the development of small and lightweight secondary batteries having a high energy density. In addition, the development of high-output secondary batteries is also required as batteries for electric vehicles such as hybrid vehicles. As a non-aqueous electrolyte secondary battery satisfying such a requirement, there is a lithium ion secondary battery. The 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 inserting lithium is used as the active material of the negative electrode and the positive electrode.

Lithium composite oxides include lithium cobalt composite oxide (LiCoO _{2 ), which is relatively easy to synthesize, lithium manganese composite oxide (LiMn 2} O ₄ ), which uses manganese, which is cheaper than cobalt, and lithium, which uses nickel. A nickel composite oxide (LiNiO ₂ ) is used. 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, higher capacity can be expected, and the battery voltage is as high as that of the cobalt type. Therefore, development is being actively carried out. However, when a lithium ion secondary battery is manufactured using a lithium nickel composite oxide synthesized purely from nickel as a positive electrode material, the becycle characteristics are inferior to those of a cobalt type, and it is relatively used or stored in a high temperature environment. A lithium nickel composite oxide in which a part of nickel is replaced with cobalt or aluminum is generally known because it has a drawback that the battery performance is easily impaired.

The general method for producing a lithium nickel composite oxide is as follows: (1) First, a nickel composite hydroxide that is a precursor of the lithium nickel composite oxide is prepared by a neutralization crystallization method, and (2) the precursor is used. A method of mixing with a lithium compound and firing is known. Among these, as a method for producing particles by the neutralization crystallization method of (1), a typical embodiment is a process using a stirring tank.

In Patent Document 1, a mixed aqueous solution containing a nickel salt and a cobalt salt, an aqueous solution containing an ammonium ion feeder, and a caustic alkaline aqueous solution are supplied and reacted in a stirring tank to obtain nickel-cobalt composite hydroxide particles. It is precipitated. It is described that by setting the ratio of the supply amount to the reaction aqueous solution amount per supply port of the mixed aqueous solution to 0.04% by volume / min or less, particles having a large particle size, high crystallinity, and a substantially spherical shape can be obtained. ing.

Japanese Unexamined Patent Publication No. 2011-201764

Conventionally, an acidic metal salt aqueous solution containing at least a nickel salt as a metal salt and a neutralizing agent that reacts with a metal salt such as a nickel salt to form a metal hydroxide are mixed and reacted in a stirring tank. A method for producing a nickel-containing hydroxide has been developed. In this production method, a complexing agent is used in addition to the aqueous metal salt solution and the neutralizing agent.

The complexing agent increases the solubility of the nickel-containing hydroxide by combining with the metal ions of the metal salt to form a complex in the alkaline reaction aqueous solution contained in the stirring tank, and the nickel-containing water. It plays a role in reducing the degree of supersaturation of oxides. Here, the degree of supersaturation of the nickel-containing hydroxide is the solubility (limit amount) of the nickel-containing hydroxide dissolved in the reaction aqueous solution from the concentration of the nickel-containing hydroxide actually dissolved in the reaction aqueous solution. It is the value obtained by subtracting.

The complexing agent slowly causes a precipitation reaction of the nickel-containing hydroxide by lowering the degree of supersaturation of the nickel-containing hydroxide in the vicinity of the supply port of the aqueous metal salt solution. As a result, particles having a large particle size and good quality can be obtained. The complex reacts with the neutralizing agent to form a metal hydroxide in the same manner as the metal salt.

Conventionally, the complexing agent has been supplied to the inside of the stirring tank separately from the aqueous metal salt solution and uniformly dispersed inside the stirring tank. Therefore, in order to promote the complexing reaction in the vicinity of the metal salt aqueous solution supply port, it is necessary to increase the concentration of the complexing agent not only in the vicinity of the metal salt aqueous solution supply port but also in the entire inside of the stirring tank. Was used a lot. On the other hand, when the amount of the complexing agent used is insufficient, the degree of supersaturation of the nickel-containing hydroxide near the supply port of the metal salt aqueous solution is large, and the precipitation reaction of the nickel-containing hydroxide rapidly proceeds to 3 μm or less. There was a problem that the proportion of fine particles in the water increased.

The present invention has been made in view of the above problems, and a main object of the present invention is to provide a method for producing a nickel-containing hydroxide, which can reduce the proportion of fine particles of 3 μm or less by efficiently using a complexing agent. And.

In order to solve the above problems, according to one aspect of the present invention,
An acidic metal salt aqueous solution containing at least a nickel salt as a metal salt, a complexing agent that combines with the metal ion of the metal salt to form a complex, and the metal salt and the complex to form a metal hydroxide. This is a method for producing a nickel-containing hydroxide, which obtains particles of a nickel-containing hydroxide by neutralization crystallization by mixing and reacting with a neutralizing agent.
A raw material solution prepared by mixing an ammonium salt which is used as the complexing agent and shows acidity when dissolved in pure water and the metal salt aqueous solution outside the stirring tank is supplied to the inside of the stirring tank.
The ammonium salt used in the raw material solution provides a method for producing a nickel-containing hydroxide having an anion different from that of the metal salt used in the raw material solution.

According to one aspect of the present invention, there is provided a method for producing a nickel-containing hydroxide, which can efficiently use a complexing agent to reduce the proportion of fine particles of 3 μm or less.

It is a flowchart of the manufacturing method of the nickel-containing hydroxide according to one Embodiment. It is sectional drawing which simplifies the aggregate formed in the first half of the particle growth process by one Embodiment. It is sectional drawing which simplifies the outer shell formed in the latter half of the particle growth process by one Embodiment. 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 VV line of FIG.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings, but in each drawing, the same or corresponding configurations will be referred to with the same or corresponding reference numerals and description thereof will be omitted.

FIG. 1 is a flowchart of a method for producing a nickel-containing hydroxide according to an embodiment. As shown in FIG. 1, the method for producing a nickel-containing hydroxide is to obtain particles of the nickel-containing hydroxide by neutralization crystallization, and to generate a nucleus of the nickel-containing hydroxide in the nucleation step S11. And a particle growth step S12 for growing nuclei. Hereinafter, each step will be described, but before that, the nickel-containing hydroxide obtained will be described.

<Nickel-containing hydroxide>
Nickel-containing hydroxide is used as a precursor of a positive electrode active material of a lithium ion secondary battery. The nickel-containing hydroxide is, for example, (1) nickel (Ni), cobalt (Co), and aluminum (Al), and the substance amount ratio (mol ratio) is Ni: Co: Al = 1-xy: x. : Y (where 0 ≦ x ≦ 0.3, 0.005 ≦ y ≦ 0.15) is a nickel composite hydroxide, or (2) nickel (Ni) and cobalt (Co). And manganese (Mn) and M (M is one or more additive elements selected from Ti, V, Cr, Zr, Nb, Mo, Hf, Ta, and W) in a substance amount ratio (mol ratio). Is Ni: Co: Mn: M = x: y: z: t (where x + y + z + t = 1, 0.1 ≦ x ≦ 0.7, 0.1 ≦ y ≦ 0.5, 0.1 ≦ z ≦ 0 It is a nickel-cobalt-manganese composite hydroxide contained so as to be 0.8, 0 ≦ t ≦ 0.02).

The amount of hydroxide ions contained in the nickel-containing hydroxide according to one embodiment usually has a stoichiometric ratio, but 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 or sulfate ion) to the extent that it does not affect the present embodiment.

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

The nickel-containing hydroxide contains nickel, preferably a metal other than nickel. A hydroxide further containing a metal other than nickel is called a nickel composite hydroxide. The metal composition ratio of the nickel composite hydroxide (for example, Ni: Co: Mn: M) is maintained in the obtained positive electrode active material, so that it matches the metal composition ratio required for the positive electrode active material. Is adjusted to.

<Manufacturing method of nickel-containing hydroxide>
As described above, the method for producing a nickel-containing hydroxide includes a nucleation step S11 and a particle growth step S12. In the present embodiment, the nucleation step S11 and the particle growth step S12 are separately carried out by controlling the pH value of the aqueous solution in the stirring tank using a batch type stirring tank.

In the nucleation step S11, the formation of nuclei takes precedence over the growth of nuclei (particle growth), and the generated nuclei hardly grow. On the other hand, in the particle growth step S12, particle growth takes precedence over nucleation and almost no new nuclei are generated. By separately performing the nucleation step S11 and the particle growth step S12, a homogeneous nucleus having a narrow particle size distribution range can be formed, and then the nucleus can be uniformly grown.

Hereinafter, the nucleation step S11 and the particle growth step S12 will be described. The pH value range is different between the aqueous solution in the stirring tank in the nucleation step S11 and the aqueous solution in the stirring tank in the particle growth step S12, but the range such as temperature may be substantially the same.

In this embodiment, a batch type stirring tank is used, but a continuous type stirring tank may be used. In the latter case, the nucleation step S11 and the particle growth step S12 are carried out at the same time. In this case, the range of the pH value of the aqueous solution in the stirring tank is naturally the same, and may be set to, for example, in the vicinity of 12.0.

(Nucleation process)
First, an acidic metal salt aqueous solution is prepared outside the stirring tank. The aqueous metal salt solution contains at least a nickel salt, and preferably further contains a metal salt other than the nickel salt. As the metal salt, nitrate, sulfate, hydrochloride and the like are used. More specifically, for example, nickel sulfate, manganese sulfate, cobalt sulfate, aluminum sulfate, titanium sulfate, ammonium peroxotitanate, potassium titanium oxalate, vanadium sulfate, ammonium vanadate, chromium sulfate, potassium chromate, zirconium sulfate, etc. Zirconium nitrate, niobium oxalate, ammonium molybdate, hafnium sulfate, sodium tantalate, sodium tungstate, ammonium tungstate and the like are used.

The metal composition ratio of the metal salt aqueous solution (for example, Ni: Co: Mn: M) is maintained in the obtained nickel composite hydroxide, so that it matches the composition ratio required for the nickel composite hydroxide. Is adjusted to.

Next, outside the stirring tank, the metal salt aqueous solution and the complexing agent are mixed to prepare a raw material liquid. The complexing agent forms a complex by combining with metal ions of a metal salt such as a nickel salt in an alkaline reaction aqueous solution described later contained in a stirring tank. As will be described in detail later, as the complexing agent used in the raw material liquid, an ammonium salt that shows acidity when dissolved in pure water is used. The raw material liquid is acidic because it is prepared by mixing an ammonium salt that shows acidity when dissolved in pure water and an aqueous solution of an acidic metal salt.

On the other hand, inside the stirring tank, a neutralizing agent and water are supplied to store the mixed aqueous solution. The mixed aqueous solution is hereinafter referred to as "pre-reaction aqueous solution". The neutralizing agent may be any one that reacts with a metal salt and 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, one containing an alkaline aqueous solution is used. As the alkaline aqueous solution, for example, one containing an alkali metal hydroxide such as sodium hydroxide and potassium hydroxide is used. The alkali metal hydroxide may be supplied as a solid, but is preferably supplied as an aqueous solution.

The aqueous solution before the reaction does not contain a complexing agent in this embodiment, but may contain a complexing agent. The complexing agent used in the pre-reaction aqueous solution may be either one that exhibits acidity when dissolved in pure water or one that exhibits alkalinity when dissolved in pure water. Examples of the complexing agent that exhibits acidity when dissolved in pure water include ammonium chloride, ammonium sulfate, ammonium nitrate, and ammonium perchlorate. On the other hand, examples of the complexing agent showing alkalinity when dissolved in pure water include ammonia and ammonium carbonate. The aqueous solution before the reaction may be alkaline.

The pH value of the aqueous solution before the reaction is adjusted within the range of 12.0 to 14.0, preferably 12.3 to 13.5, based on the liquid temperature of 25 ° C. The temperature of the aqueous solution before the reaction is preferably adjusted within the range of 20 to 60 ° C, more preferably 35 to 60 ° C. The pH value and temperature of the pre-reaction aqueous solution can be measured with a known pH meter, thermometer or the like, respectively. When the pre-reaction aqueous solution contains a complexing agent, the ammonium ion concentration in the pre-reaction aqueous solution is preferably in the range of 3 to 25 g / L, more preferably 5 to 20 g / L, and even more preferably 5 to 15 g / L. Adjust it inside. The ammonium ion concentration of the pre-reaction aqueous solution can be measured with a known ion meter or the like.

After adjusting the pH value and temperature of the pre-reaction aqueous solution, 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. In the reaction aqueous solution, nickel-containing hydroxide is precipitated by neutralization crystallization, fine nuclei made of nickel-containing hydroxide are generated, and the nucleation step S11 is started.

In the nucleation step S11, nickel-containing hydroxide is produced by the following two routes. In the first route, a metal salt such as a nickel salt contained in the aqueous metal salt solution reacts with an aqueous alkaline solution as a neutralizing agent to produce a nickel-containing hydroxide. For example, nickel ions contained in an aqueous metal salt solution react with a hydroxyl group of sodium hydroxide as shown in the following formula (1) to produce nickel hydroxide. In the second route, first, a metal salt such as nickel salt contained in the metal salt aqueous solution is combined with ammonia or the like as a complexing agent to form a complex. After that, the complex reacts with an alkaline aqueous solution as a neutralizing agent to produce a nickel-containing hydroxide. For example, nickel ions contained in a metal salt aqueous solution react with ammonia in the reaction aqueous solution as shown in the following formula (2-1) to form a nickel ammine complex ([Ni (NH ₃ ) ₆ ] ²⁺ ). Then, the nickel ammine complex reacts with the hydroxyl group of sodium hydroxide as shown in the following formula (2-2) to produce a nickel hydroxide. Similarly, in the particle growth step S12, a nickel-containing hydroxide is produced.
^{Ni 2+ + 2OH - → Ni (} OH) 2 ··· (1)
Ni ²⁺ + 6NH ₃ → [Ni (NH ₃ ) ₆ ] ²⁺ ... (2-1)
^{_{[Ni (NH 3) 6]}} 2+ + 2OH - → Ni (OH) 2 + 6NH 3 ··· (2-2)
The pH value and temperature of the reaction aqueous solution are adjusted so as to be maintained within the same range as the pH value and temperature of the pre-reaction aqueous solution. When the pre-reaction aqueous solution contains a complexing agent, the ammonium ion concentration of the reaction aqueous solution may be adjusted so as to be maintained within the same range as the ammonium ion concentration of the pre-reaction aqueous solution.

In the nucleation step S11, when the pH value of the reaction aqueous solution is 12.0 or more, nucleation becomes dominant over particle growth. When the pH value of the reaction aqueous solution is 14.0 or less in the nucleation step S11, it is possible to prevent the nuclei from becoming too fine and to prevent the reaction aqueous solution from gelling. In the nucleation step S11, 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 nucleation step S11, when the temperature of the reaction aqueous solution is 20 ° C. or higher, the solubility of the nickel-containing hydroxide is high, so that nucleation occurs slowly and nucleation can be easily controlled. When the temperature of the reaction aqueous solution is 60 ° C. or lower, the volatilization of ammonia contained in the complexing agent can be suppressed, so that the amount of the complexing agent used can be reduced and the production cost can be reduced.

In the nucleation step S11, a neutralizing agent is supplied into the stirring tank in addition to the raw material liquid so that the pH value and temperature of the reaction aqueous solution are maintained within the above ranges. As a result, the formation of nuclei continues in the reaction aqueous solution. Then, when a predetermined amount of nuclei are generated, the nucleation step S11 is completed. Whether or not a predetermined amount of nuclei are produced can be estimated from the amount of metal salt supplied. If the amount of the complexing agent contained in the raw material liquid is insufficient in the nucleation step S11, the complexing agent may be supplied to the inside of the stirring tank separately from the raw material liquid.

(Particle growth process)
After the completion of the nucleation step S11 and before the start of the particle growth step S12, the pH value of the reaction aqueous solution in the stirring tank was adjusted to 10.5-12.0, preferably 11.0-12, based on a liquid temperature of 25 ° C. The pH value is adjusted to 0.0 and lower than the pH value in the nucleation step S11. To adjust the pH value, stop the supply of the neutralizing agent into the stirring tank, and supply an inorganic acid (for example, sulfuric acid in the case of sulfate) in which the metal of the metal salt is replaced with hydrogen into the stirring tank. It can be adjusted by things.

After adjusting the pH value and temperature of the reaction aqueous solution, the raw material liquid is supplied into the stirring tank while stirring the reaction aqueous solution. As a result, nuclear growth (particle growth) is started by neutralization crystallization, and the particle growth step S12 is started. In the present embodiment, the nucleation step S11 and the particle growth step S12 are performed in the same stirring tank, but may be performed in different stirring tanks.

In the particle growth step S12, if the pH value of the reaction aqueous solution is 12.0 or less and lower than the pH value in the nucleation step S11, almost no new nuclei are generated, and the particle growth is more than the nucleation. It occurs with priority.

When the pH value is 12.0, it is a boundary condition between nucleation and particle growth, so the priority order changes depending on the presence or absence of nuclei present in the reaction aqueous solution. For example, if the pH value of the nucleation step S11 is set higher than 12.0 to generate a large amount of nuclei and then the pH value is set to 12.0 in the particle growth step S12, a large amount of nuclei are present in the reaction aqueous solution. , Particle growth takes precedence. On the other hand, when there are no nuclei in the reaction aqueous solution, that is, when the pH value is set to 12.0 in the nucleation step S11, nucleation is prioritized because there are no nuclei to grow. After that, if the pH value is made smaller than 12.0 in the particle growth step S12, the generated nuclei grow. In order to clearly separate nucleation and particle growth, the pH value of the particle growth step is preferably 0.5 or more lower than the pH value of the nucleation step, and more preferably 1.0 or more.

Further, in the particle growth step S12, when the pH value of the reaction aqueous solution is 10.5 or more, the solubility due to ammonia is low, so that the metal ions remaining in the liquid without precipitation are reduced, and the production efficiency is improved.

In the particle growth step S12, a neutralizing agent is supplied into the stirring tank in addition to the raw material liquid so that the pH value and temperature of the reaction aqueous solution are maintained within the above ranges. As a result, particle growth is continued in the reaction aqueous solution. If the amount of the complexing agent contained in the raw material liquid is insufficient in the particle growth step S12, the complexing agent may be supplied to the inside of the stirring tank separately from the raw material liquid.

The particle growth step S12 can be divided into the first half and the second half by switching the atmosphere in the stirring tank. The atmosphere in the first half of the particle growth step S12 is an oxidizing atmosphere as in the nucleation step S11. The oxygen concentration in the oxidizing atmosphere is 1% by volume or more, preferably 2% by volume or more, and more preferably 10% by volume or more. The oxidizing atmosphere may be an air atmosphere (oxygen concentration: 21% by volume) that is easy to control. The upper limit of the oxygen concentration in the oxidizing atmosphere is not particularly limited, but is 30% by volume or less. On the other hand, the atmosphere in the latter half of the particle growth step S12 is a non-oxidizing atmosphere. The oxygen concentration in the non-oxidizing atmosphere is less than 1% by volume, preferably 0.5% by volume or less, and more preferably 0.3% by volume or less. The oxygen concentration in the non-oxidizing atmosphere is controlled by mixing the oxygen gas or the atmosphere with an inert gas.

FIG. 2 is a cross-sectional view schematically showing the agglomerates formed in the first half of the particle growth step S12 according to the embodiment. FIG. 3 is a cross-sectional view schematically showing the outer shell formed in the latter half of the particle growth step S12 according to the embodiment.

In the first half of the particle growth step S12, the seed crystal particles 2 are formed by the growth of the nucleus, and when the seed crystal particles 2 become large to some extent, the seed crystal particles 2 collide with each other, and the seed crystal particles 2 start to collide with each other. Aggregates 4 are formed. On the other hand, in the latter half of the particle growth step S12, a dense outer shell 6 is formed around the aggregate 4. As a result, nickel-containing hydroxide particles composed of the aggregate 4 and the outer shell 6 are obtained.

The structure of the nickel-containing hydroxide particles is not limited to the structure shown in FIG. For example, when the nucleation step S11 and the particle growth step S12 are carried out at the same time, the structure of the particles obtained at the completion of the neutralization crystallization is different from the structure shown in FIG. The structure is, for example, a uniform structure in which the one corresponding to the seed crystal particle 2 and the one corresponding to the outer shell 6 are mixed and the boundary thereof is not easily known.

When the nickel-containing hydroxide particles have grown to a predetermined particle size, the particle growth step S12 is terminated. The particle size can be estimated from the amount of metal salt supplied in each of the nucleation step S11 and the particle growth step S12.

After the nucleation step S11 is completed, in the middle of the particle growth step S12, the supply of the raw material liquid and the like is stopped, the stirring of the reaction aqueous solution is stopped, the nickel-containing hydroxide particles are precipitated, and then the supernatant is obtained. The liquid may be drained. As a result, the metal ion concentration in the reaction aqueous solution reduced by neutralization crystallization can be increased.

FIG. 4 is a top view showing a chemical reaction apparatus used in the method for producing a nickel-containing hydroxide according to one embodiment. FIG. 5 is a cross-sectional view of the chemical reaction apparatus along the VV line of FIG. As shown in FIGS. 4 and 5, the chemical reaction apparatus 10 includes a stirring tank 20, a stirring blade 30, a stirring shaft 40, and a baffle 50. The stirring tank 20 accommodates the reaction aqueous solution in a columnar internal space. The stirring blade 30 stirs the reaction aqueous solution in the stirring tank 20. The stirring blade 30 is attached to the lower end of the stirring shaft 40. The stirring blade 30 is rotated by rotating the stirring shaft 40 by a motor or the like. The center line of the stirring tank 20, the center line of the stirring blade 30, and the center line of the stirring shaft 40 may coincide with each other and may be vertical. The baffle 50 is also called a baffle plate. The baffle 50 protrudes from the inner peripheral surface of the stirring tank 20 and interferes with the rotating flow to generate an ascending flow and a descending flow, improving the stirring efficiency of the reaction aqueous solution.

Further, the chemical reaction apparatus 10 has a raw material liquid supply pipe 60 and a neutralizer supply pipe 62. The raw material liquid supply pipe 60 supplies the raw material liquid into the stirring tank 20 from the supply port 61. The neutralizing agent supply pipe 62 supplies the neutralizing agent into the stirring tank 20 from the supply port 63. The chemical reaction apparatus 10 may have a complexing agent supply pipe in addition to the raw material liquid supply pipe 60 and the neutralizer supply pipe 62. The complexing agent supply pipe supplies the complexing agent to the inside of the stirring tank 20. The complexing agent supplied to the inside of the stirring tank 20 by the complexing agent supply pipe may be either one that exhibits acidity when dissolved in pure water or one that exhibits alkalinity when dissolved in pure water. Since the raw material liquid of the present embodiment contains a complexing agent, the chemical reaction apparatus 10 does not have to have a complexing agent supply pipe.

By the way, in the present embodiment, a raw material solution prepared by mixing an ammonium salt and a metal salt aqueous solution, which are used as a complexing agent and show acidity when dissolved in pure water, outside the stirring tank 20 is placed inside the stirring tank 20. Supply.

If an ammonium salt to be mixed with an aqueous metal salt solution that is alkaline when dissolved in pure water is used, a hydroxyl group is generated at least during mixing. As a result, a reaction between the hydroxyl group and the metal ion (for example, the reaction of the above formula (1)) occurs, nickel-containing hydroxide is generated, and nickel-containing hydroxide is precipitated.

According to the present embodiment, since the raw material liquid is prepared by mixing an ammonium salt that shows acidity when dissolved in pure water and an acidic metal salt aqueous solution, it is possible to prevent the formation of hydroxyl groups in the raw material liquid. Therefore, the reaction between the hydroxyl group and the metal ion in the raw material liquid can be suppressed, the formation reaction of the nickel-containing hydroxide in the raw material liquid can be suppressed, and the precipitation reaction of the nickel-containing hydroxide in the raw material liquid can be suppressed. can.

The raw material solution is acidic because it is prepared by mixing an ammonium salt that is acidic when dissolved purely and an aqueous solution of an acidic metal salt. Therefore, the complexing reaction in the raw material liquid (for example, the reaction of the above formula (2-1)) does not occur. Prior to the complexing reaction, it is important to suppress the reaction between the hydroxyl group and the metal ion to suppress the precipitation reaction of the nickel-containing hydroxide as described above from the viewpoint of obtaining the effect of the complexing agent. The complexing reaction occurs in an alkaline reaction aqueous solution contained inside the stirring tank 20.

Since the reaction aqueous solution contained in the stirring tank 20 is alkaline, the reaction between the metal ion and the hydroxyl group (for example, the reaction of the above formula (1)) and the metal ion near the supply port 61 of the raw material liquid supply pipe 60 And the reaction with ammonia (for example, the reaction of the above formula (2-1)) both occur. These reactions basically occur in the vicinity of the supply port 61 of the raw material liquid supply pipe 60.

Since the raw material liquid is prepared by mixing the metal salt aqueous solution and the complexing agent, the complexing agent can be efficiently supplied to the vicinity of the supply port 61 of the raw material liquid supply pipe 60. The complexing agent increases the solubility of the nickel-containing hydroxide in the vicinity of the supply port 61 and lowers the supersaturation of the nickel-containing hydroxide. As a result, the precipitation reaction of the nickel-containing hydroxide occurs slowly, and particles having a large particle size and good quality can be obtained. Therefore, the complexing agent can be efficiently used to reduce the proportion of fine particles of 3 μm or less.

As the ammonium salt used in the raw material liquid, at least one selected from ammonium chloride, ammonium sulfate, ammonium nitrate and ammonium perchlorate is used. Since these ammonium salts are acidic when dissolved in pure water, they do not generate hydroxyl groups when mixed with an aqueous metal salt solution.

The ammonium salt used in the raw material solution preferably has an anion different from that of the metal salt used in the raw material solution. For example, when the anion of the metal salt used in the raw material solution is sulfate ion (that is, when the metal salt contains nickel sulfate), the anion of the ammonium salt used in the raw material solution is other than sulfate ion (for example, chlorine ion). ) Is preferable. As a result, the common-ion effect can be suppressed and the ammonium salt can be easily dissolved in water.

The ammonium salt used in the raw material liquid may be mixed with the metal salt aqueous solution as a solid, or may be mixed with the metal salt aqueous solution as an aqueous solution dissolved in water. When a solid ammonium salt and an aqueous metal salt solution are mixed, a decrease in the concentration of the metal salt in the raw material liquid can be suppressed. Further, when the ammonium salt previously dissolved in water and the aqueous metal salt solution are mixed, the undissolved residue of the ammonium salt can be reduced.

The molar ratio of all the metal salts in the raw material liquid to the complexing agent may be set so that the complex formation reaction proceeds sufficiently. The ratio (B / A) of the number of moles (B) of the complexing agent to the total number of moles (A) of all the metal salts is, for example, 0.05 or more and 1 or less. When the ratio (B / A) is 0.05 or more, the complex formation reaction can be sufficiently promoted in the vicinity of the raw material liquid supply port 61. When the ratio (B / A) is 1 or less, the use of an excessive complexing agent can be prevented.

[Example 1]
In Example 1, an overflow-type continuous stirring tank is used, and a nucleation step of forming nuclei of nickel composite hydroxide particles and a particle growth step of growing particles are simultaneously performed by neutralization crystallization. rice field. The volume of the stirring tank is 200L, the type of stirring blade is a disc turbine blade, the number of blades of the stirring blade is 6, the blade diameter of the stirring blade is 250 mm, and the vertical distance between the stirring blade and the inner bottom surface of the stirring tank is The rotation speed of the stirring blade was 140 mm and 280 rpm. The amount of the reaction aqueous solution in the stirring tank was maintained at 200 L, the pH value of the reaction aqueous solution was maintained at 11.3, and the temperature of the reaction aqueous solution was maintained at 50 ° C. The surrounding atmosphere of the reaction aqueous solution was an atmospheric atmosphere.

The metal salt aqueous solution was _{prepared so that Ni 0.82} Co _0.15 Al _0.03 (OH) ₂ could be obtained as a nickel composite hydroxide. Moreover, the raw material liquid was prepared by mixing the prepared metal salt aqueous solution and solid ammonium chloride. The ratio (B / A) of the number of moles of ammonium chloride (B) to the total number of moles (A) of all the metal salts (nickel salt, cobalt salt and aluminum salt) in the raw material liquid was 0.2. The number of raw material liquid supply pipes was one, and the amount supplied from each raw material liquid supply pipe was 400 ml / min.

During the nucleation step and the particle growth step, an aqueous sodium hydroxide solution was supplied as a neutralizing agent in the stirring tank in addition to the raw material solution to maintain the pH value of the reaction aqueous solution. The ammonium ion concentration in the reaction aqueous solution contained in the stirring tank in the steady state was kept constant at 5 g / L.
When the particle size distribution of the obtained nickel composite hydroxide was measured using a laser diffraction / scattering type particle size distribution measuring device, it was 3 μm or less in the particles of the nickel composite hydroxide obtained in Example 1. The proportion of fine particles was 0%.

[Example 2]
In Example 2, the nickel composite was prepared in the same manner as in Example 1 except that the _{aqueous metal salt solution was prepared so as to obtain Ni 0.34} Co _0.33 Mn _0.33 (OH) _{2 as the nickel composite hydroxide.} Hydroxide particles were produced.

When the particle size distribution of the nickel composite hydroxide obtained in Example 2 was measured in the same manner as in Example 1, the proportion of fine particles of 3 μm or less in the particles was 0%.

[Comparative Example 1]
In Comparative Example 1, nickel composite hydroxide particles were produced in the same manner as in Example 1 except that the metal salt aqueous solution and the complexing agent were supplied to the inside of the stirring tank using separate supply pipes. Ammonium chloride as a complexing agent was made into an aqueous solution (ammonium chloride concentration 1 mol / L) and supplied to the inside of the stirring tank. The ammonium ion concentration in the reaction aqueous solution contained in the stirring tank in the steady state was set to 5 g / L as in Example 1.

When the particle size distribution of the nickel composite hydroxide obtained in Comparative Example 1 was measured in the same manner as in Example 1, the proportion of fine particles of 3 μm or less in the particles was 6%.

[Comparative Example 2]
In Comparative Example 2, nickel composite hydroxide particles were produced in the same manner as in Example 1 except that a raw material liquid was prepared by mixing a complexing agent showing alkalinity when dissolved in pure water and an aqueous metal salt solution. Ammonia as a complexing agent was made into aqueous ammonia and then mixed with an aqueous metal salt solution. The ammonium ion concentration in the reaction aqueous solution contained in the stirring tank in the steady state was set to 5 g / L as in Example 1.

When the particle size distribution of the nickel composite hydroxide obtained in Comparative Example 2 was measured in the same manner as in Example 1, the proportion of fine particles of 3 μm or less in the particles was 20%.

[Comparative Example 3]
In Comparative Example 3, nickel composite hydroxide particles were produced in the same manner as in Example 2 except that the metal salt aqueous solution and the complexing agent were supplied to the inside of the stirring tank using separate supply pipes. Ammonium chloride as a complexing agent was made into an aqueous solution (ammonium chloride concentration 1 mol / L) and supplied to the inside of the stirring tank. The ammonium ion concentration in the reaction aqueous solution contained in the stirring tank in the steady state was set to 5 g / L as in Example 2.

When the particle size distribution of the nickel composite hydroxide obtained in Comparative Example 3 was measured in the same manner as in Example 1, the proportion of fine particles of 3 μm or less in the particles was 5%.

[Comparative Example 4]
In Comparative Example 4, nickel composite hydroxide particles were produced in the same manner as in Example 2 except that a raw material liquid was prepared by mixing a complexing agent showing alkalinity when dissolved in pure water and an aqueous metal salt solution. Ammonia as a complexing agent was made into aqueous ammonia and then mixed with an aqueous metal salt solution. The ammonium ion concentration in the reaction aqueous solution contained in the stirring tank in the steady state was set to 5 g / L as in Example 2.

When the particle size distribution of the nickel composite hydroxide obtained in Comparative Example 4 was measured in the same manner as in Example 1, the proportion of fine particles of 3 μm or less in the particles was 18%.

[summary]
From Examples 1 and 2 and Comparative Examples 1 to 4, a raw material solution prepared by mixing an ammonium salt showing acidity when dissolved in pure water and an acidic metal salt aqueous solution outside the stirring tank is placed inside the stirring tank. It can be seen that the complexing agent can be efficiently used to reduce the proportion of fine particles of 3 μm or less.

Although the embodiment of the method for producing a nickel-containing hydroxide has been described above, the present invention is not limited to the above-mentioned embodiments and the like, and is within the scope of the gist of the present invention described in the claims. , Various modifications and improvements are possible.

2 Species particles 4 Aggregates 6 Outer shell 10 Chemical reactor 20 Stirring tank 30 Stirring blade 40 Stirring shaft 50 Baffle 60 Raw material liquid supply pipe 61 Supply port 62 Neutralizer supply pipe

Claims (4)

An acidic metal salt aqueous solution containing at least a nickel salt as a metal salt, a complexing agent that combines with the metal ion of the metal salt to form a complex, and the metal salt and the complex to form a metal hydroxide. This is a method for producing a nickel-containing hydroxide, which obtains particles of a nickel-containing hydroxide by neutralization crystallization by mixing and reacting with a neutralizing agent.
A raw material solution prepared by mixing an ammonium salt which is used as the complexing agent and shows acidity when dissolved in pure water and the metal salt aqueous solution outside the stirring tank is supplied to the inside of the stirring tank.
A method for producing a nickel-containing hydroxide, wherein the ammonium salt used in the raw material solution has an anion different from that of the metal salt used in the raw material solution. The method for producing a nickel-containing hydroxide according to claim 1, wherein the raw material solution contains at least one selected from ammonium chloride, ammonium sulfate, ammonium nitrate and ammonium perchlorate as the ammonium salt. The nickel-containing hydroxide contains 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 or 2, which comprises y ≦ 0.15). 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 (where x + y + z + t = 1, 0.1 ≦ x ≦ 0.7, 0.1 ≦ y ≦ 0.5, 0.1 The method for producing a nickel-containing hydroxide according to claim 1 or 2, which comprises ≦ z ≦ 0.8 and 0 ≦ t ≦ 0.02).

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