JP2014111828A - Nickel hydroxide, method for producing the same, and obtained nickel oxide - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing high purity nickel oxide having higher crystallinity, which comprises electrolytically dissolving high purity metallic nickel, forming high purity nickel hydroxide, in particular, extremely low in sulfur as an impurity, and then roasting the nickel hydroxide.SOLUTION: A method for producing nickel hydroxide is characterized by installing an anode and a cathode in an electrolytic cell, using metallic nickel on the anode side, charging, as an electrolytic solution, a mixed solution of ammonium nitrate and an ammonium halide, performing electrolysis at a pH of 6 or higher to form a nickel ammine complex, and precipitating saturated nickel ammine complex as particulate nickel hydroxide.

Description

  The present invention relates to nickel hydroxide, a process for producing the same, and the resulting nickel oxide. More specifically, nickel hydroxide having a very small amount of impurities such as sodium and sulfur is produced by electrolysis using metallic nickel as an anode, and the water The present invention relates to nickel hydroxide capable of obtaining high-purity nickel oxide by roasting nickel oxide, a method for producing the same, and the obtained nickel oxide.

  Nickel hydroxide and nickel oxide are widely used as raw materials for positive electrode materials for secondary batteries such as nickel metal hydride batteries and lithium ion batteries, and electrode materials for solid oxide fuel cells. Hybrid cars and electric cars are expected to become popular in the future, and as a new power generation system replacing nuclear power generation, a combined power generation system combining thermal power generation and fuel cells is being put into practical use. As a result, demand for nickel hydroxide and nickel oxide is expected to increase in the future. In such applications, nickel hydroxide and nickel oxide are required to have high purity and a small particle size.

  Generally, nickel hydroxide is produced by adding sodium hydroxide or the like to a solution containing a nickel salt such as nickel sulfate, nickel chloride, or nickel nitrate to make it alkaline (see, for example, Patent Document 4). . According to Patent Document 4, ammonia is added to an aqueous solution containing a nickel salt to form a nickel-ammonium complex salt, and a caustic alkali is allowed to act on this to precipitate nickel hydroxide.

  In such a method for obtaining nickel hydroxide, the principle is simple, but many steps are required for implementation, and sodium hydroxide is used to make the reaction solution alkaline. Since it becomes a residual impurity, not only a large amount of washing waste liquid is generated in the washing process, but also the waste liquid containing sodium nitrate or sulfate after the reaction needs to be treated.

By the way, nickel oxide is obtained by roasting the above nickel hydroxide, nickel sulfate, nickel chloride, nickel nitrate or the like in an oxidizing atmosphere.
For example, Patent Document 1 proposes a method of roasting nickel sulfate at a maximum temperature of 900 to 1250 ° C. while forcibly introducing air using a horizontal rotary manufacturing furnace. According to this method, nickel oxide powder having a sulfur quality of 500 ppm by mass or less is obtained.
In Patent Document 2, a nickel sulfate aqueous solution is neutralized with an alkali, and the obtained nickel hydroxide is heat-treated under predetermined conditions, whereby sulfur quality is controlled and fine oxidation with low impurity quality, particularly chlorine quality. A method for obtaining nickel fine powder has been proposed. However, in order to make the sulfur grade in the obtained nickel oxide less than 50 ppm by mass, it is necessary to set the roasting temperature to 950 ° C. or higher. For this reason, D90 also tends to increase to 3 μm or more.

On the other hand, there is also a method of producing nickel hydroxide by electrolysis from nickel metal in addition to the method of producing nickel hydroxide by chemical precipitation as described above.
For example, Patent Document 3 proposes a method of precipitating spherical nickel hydroxide by dissolving a nickel electrode at an anode. This method does not contain sulfur as an impurity, but electrolysis is performed at a high chlorine concentration, pH value, and temperature, and the pH is adjusted with an electrolyte containing sodium salt. In the resulting nickel oxide, there is a concern that Na remains and the amount of residual chlorine increases.

  For this reason, there has been a need for a production method in which nickel hydroxide can be efficiently produced from nickel metal by electrolysis, Na residue does not remain, and high-purity nickel oxide with reduced residual chlorine content can be obtained.

JP 2004-189530 A JP 2011-225395 A Special Table 2002-544382 JP-A-56-143671

  The object of the present invention is to produce nickel hydroxide with very few impurities such as sodium and sulfur by electrolytic method using metallic nickel as an anode, and to obtain high-purity nickel oxide by baking the nickel hydroxide. It is an object of the present invention to provide nickel hydroxide, a method for producing the same and nickel oxide obtained.

  As a result of diligent research to solve the above-mentioned problems, the present inventors have made nickel nickel as the anode side and used a mixed solution of ammonium nitrate and ammonium halide as the electrolytic solution, so that the pH of the electrolytic solution during electrolysis is 6 It has been found that nickel hydroxide with very little sulfur as an impurity is produced, and subsequently, the nickel hydroxide can be produced by high-purity and high crystallinity by baking this nickel hydroxide. As a result, the present invention has been completed.

  That is, according to the first invention of the present invention, an anode and a cathode are installed in an electrolytic cell, metallic nickel is used as the anode side, a mixed solution of ammonium nitrate and ammonium halide is charged as an electrolyte, and the pH is 6 or more. There is provided a method for producing nickel hydroxide characterized in that, by electrolysis, a nickel ammine complex is produced and a saturated nickel ammine complex is precipitated as particulate nickel hydroxide.

  According to the second invention of the present invention, in the first invention, the cathode is selected from the group consisting of platinum, titanium, platinum-plated titanium, titanium-plated platinum, nickel, and stainless steel. There is provided a method for producing nickel hydroxide, characterized in that one metal is used.

  According to the third invention of the present invention, in the first or second invention, the concentration of ammonium nitrate in the electrolytic solution is 0.1 to 5.0 mol / l. Is provided.

  According to a fourth invention of the present invention, in any one of the first to third inventions, the ammonium halide concentration is 1.0 mol / l or less. Is provided.

  According to a fifth aspect of the present invention, there is provided the method for producing nickel hydroxide according to any one of the first to fourth aspects, wherein the ammonium halide is ammonium chloride.

  According to a sixth aspect of the present invention, there is provided a method for producing nickel hydroxide, characterized in that in any one of the first to fifth aspects, the pH of the electrolyte is in the range of 6-9. The

  According to the seventh aspect of the present invention, in any one of the first to sixth aspects, the content of any component of Cr, Fe, Si, Co, Ca, Na, Zr, P, and Mn is 10 There is provided nickel hydroxide having a mass of less than ppm, a chlorine content of less than 50 ppm, and a sulfur content of less than 1 ppm.

Furthermore, according to the eighth aspect of the present invention, there is provided nickel hydroxide according to the seventh aspect, wherein the average particle size is 3 to 200 μm and the specific surface area is 10 to 200 m ² / g. The

  On the other hand, according to the ninth invention of the present invention, in the seventh or eighth invention, it is obtained by roasting nickel hydroxide in an oxidizing atmosphere at a temperature range of 800 to 1000 ° C., and Cr, Fe, Si , Co, Ca, Na, Zr, P, and Mn have a content of less than 10 mass ppm, a chlorine content of less than 50 mass ppm, a sulfur content of less than 1 mass ppm, Nickel oxide having a content of less than 50 ppm by mass is provided.

  According to the tenth aspect of the present invention, in the ninth aspect, nickel oxide used as an electrode material for a solid electrolyte fuel cell is provided.

  According to the present invention, metallic nickel is used as the anode side, and a mixed solution of ammonium nitrate and ammonium halide is used as the electrolytic solution, and high-purity metallic nickel is dissolved by electrolysis, so that the nickel ammine complex is saturated and the alkali metal is Very little high purity nickel hydroxide can be produced.

  Further, by baking the obtained nickel hydroxide, it is possible to easily produce a large amount of nickel oxide having high purity and high crystallinity. Even in this step, the generated NOx can be reduced with hydrogen generated during electrolysis, so that there is an advantage in safety and health.

It is process drawing which manufactures nickel hydroxide by this invention, and also manufactures nickel oxide. It is the photograph which observed the nickel hydroxide manufactured by Example 1 with the electron microscope. It is an electric potential-pH figure which shows the relationship between pH and electric potential when electrolyzing metallic nickel in an electrolytic vessel and producing | generating nickel hydroxide. It is a chart which shows the X-ray-diffraction result of the nickel hydroxide obtained by this invention. It is a chart which shows the X-ray-diffraction result of the nickel oxide obtained by this invention.

  The method for producing nickel hydroxide of the present invention, the resulting nickel hydroxide, and the nickel oxide obtained using the same will be described with reference to the drawings.

1. Method for Producing Nickel Hydroxide The method for producing nickel hydroxide of the present invention comprises an anode and a cathode installed in an electrolytic cell, nickel metal as the anode side, and a mixed solution of ammonium nitrate and ammonium halide as an electrolyte. The nickel ammine complex is formed by electrolysis at pH 6 or higher, and the saturated nickel ammine complex is precipitated as particulate nickel hydroxide.

  FIG. 1 shows a production process of nickel oxide in the present invention. First, nickel hydroxide is produced in an electrolytic cell 1 in which an anode 2, a cathode 3 and an electrolyte 4 of electrodes are charged, and then the electrolyte is produced. And nickel hydroxide are filtered, washed with water and filtered. These solutions and washing water are returned to the electrolyte again, so that the apparatus configuration is relatively simple but closed. The nickel hydroxide that has been washed with water is roasted at a high temperature in the next step to form nickel oxide. Thereafter, the baked product is crushed and made into nickel oxide of an arbitrary size to obtain a product.

(1) Electrode Although the cathode 3 in the electrolytic cell 1 should just be a metal through which electricity flows, it is preferable to use a metal electrode with a small hydrogen overvoltage. By using a metal having a low hydrogen overvoltage, precipitation of metallic nickel on the electrode surface can be suppressed. If metallic nickel is deposited, it will be peeled off from the cathode and mixed into nickel hydroxide, which is not preferable.

  Examples of the metal electrode include platinum, titanium, platinum-plated titanium, a clad of titanium and platinum, nickel, stainless steel, and the like. In particular, when nickel is selected as the cathode, even if nickel is deposited on the electrode surface, it does not peel off and can be suitably used. Moreover, since it can be used as an anode after being used for the cathode, there is an advantage that the maintenance cost of the cathode is not required. On the other hand, since the nickel metal used for the anode 2 becomes nickel hydroxide as it is, it is desirable to use a product having the highest purity as possible and use commercially available nickel (purity of 3N or more).

(2) Electrolytic Solution In the present invention, selection of the electrolytic solution 4 is important, and ammonium nitrate and ammonium halide are used as an ammonia source.

  Ammonium nitrate is used to remove nitrate radicals remaining in the nickel hydroxide produced after the electrolytic reaction at a relatively low temperature. The concentration of ammonium nitrate is preferably in the range of 0.1 to 5.0 mol / l. A more preferred concentration is in the range of 0.4 to 1.0 mol / l. When it is 0.1 mol / l or more, the secondary particles of nickel hydroxide to be generated become large, and the workability when recovered by filtration is improved. However, if the concentration exceeds 5.0 mol / l, it takes time to start crystallization of nickel hydroxide, which is not preferable.

  In the present invention, it is necessary to add ammonium halide simultaneously with ammonium nitrate. The purpose of adding ammonium halide is to facilitate dissolution of metallic nickel by the action of halogen ions. The ammonium halide is not particularly limited, but examples include ammonium chloride and ammonium bromide, and ammonium chloride is more preferable. Note that ammonium bromide is preferably used when it is desired to avoid mixing chlorine as an impurity.

  If the amount of ammonium halide added is too small, the dissolution rate of metallic nickel decreases, and if the amount added is large, the concentration of impurity halogen contained in nickel hydroxide increases, which is not preferable. Therefore, the concentration of ammonium halide is preferably 1.0 mol / l or less, and more preferably 0.1 to 0.5 mol / l. The amount of ammonium halide added to ammonium nitrate is not particularly limited, but the molar ratio of ammonium halide / ammonium nitrate is preferably in the range of 0.1 / 1 to 1/1. More preferably, it is in the range of / 1 to 0.8 / 1, and most preferably in the range of 0.3 / 1 to 0.5 / 1.

  On the other hand, when an alkali metal compound such as a sodium salt is used as in the conventional method, the alkali metal is mixed into the nickel hydroxide as an impurity, so that a high-purity product cannot be obtained.

(3) Electrolytic conditions Reaction formulas in which nickel hydroxide is generated by electrolysis in the present invention are shown in the following formulas (1) to (4). When the anode 2 and the cathode 3 of the electrode are installed in the electrolytic cell 1 and the electrolytic solution 4 is put in the cell and then a current is passed between the electrodes, the metallic nickel as the anode is dissolved (formula (1)), and the cathode Ammine complex is formed with ammonia generated in the vicinity (formula (3)). When the dissolution of nickel proceeds and the nickel ammine complex is eventually saturated, nickel hydroxide particles are generated (formula (4)) and precipitated.

[Chemical 1]
Ni → Ni ²⁺ + 2e ⁻ (anode) (1)

[Chemical formula 2]
2H ₂ O + 2e ⁻ → H ₂ + 2OH ⁻ (cathode) (2)

[Chemical formula 3]
Ni ²⁺ + 6NH ₃ → [Ni (NH ₃ ) ₆ ] ²⁺ (3)

[Chemical formula 4]
[Ni (NH ₃ ) ₆ ] ²⁺ + 2OH ⁻ → Ni (OH) ₂ + 6NH ₃ (4)

  At this time, the pH of the electrolytic solution 4 needs to be 6 or more. FIG. 3 shows “Marcel Pourbaix,“ Atlas of Electrochemical Equilibrium in Aqueous Solutions ”—Negative Association of Corrosion Engineers (pH 1974). As can be seen, nickel hydroxide is not formed. A preferred pH is in the range of 6-9. If the pH is higher than 9, the ammonia in the electrolytic cell tends to evaporate, it becomes difficult to control the ammonia concentration, and the working environment may be deteriorated.

  Further, the temperature of the liquid in the electrolytic cell 1 is not particularly limited, but if it is too low, the decomposition reaction of the nickel ammine complex is lowered and the amount of nickel hydroxide produced is reduced. On the other hand, if it is too high, the electrolytic solution 4 evaporates, and the heater consumes electric power, which increases the cost. Therefore, it is desirable to electrolyze at 10-70 degreeC, and the range of 15-65 degreeC is preferable.

The current density of the electrode is not particularly limited, but if it is low, the amount of nickel hydroxide produced will decrease, and if it is high, the amount of nickel hydroxide produced will increase, but the residue will also increase and the power source will also increase. It is uneconomical. Therefore, the current density is 3 to 20 A / dm ² and more preferably 5 to 15 A / dm ² .
Note that ammonia generated from the electrolytic cell due to the ammonia source of the electrolytic solution can be absorbed by dilute nitric acid and refluxed into the electrolytic cell 1 to be rendered harmless.

(4) Recovery of nickel hydroxide After electrolysis under the above electrolysis conditions, the produced nickel hydroxide and the electrolytic solution are separated by filtration, and after washing with water, nickel hydroxide is recovered. The conditions of filtration separation and washing with water are not particularly limited, but it is simple and preferable to perform centrifugal filtration separation or suction filtration separation.

As described above, when the ammonium nitrate concentration is 0.4 mol / l or more, the primary particles of the nickel hydroxide that are produced aggregate to increase the secondary particles, improve the sedimentation, and form pores between the secondary particles. As a result, it becomes easy to filter and wash. This means that the working efficiency is improved and nickel hydroxide can be recovered economically. The filtration method is not particularly limited, but it is efficient to use a filter press, centrifugal separation or the like.
Washed water obtained by washing and filtering the electrolytic solution and nickel hydroxide after filtration separation can be returned to the electrolytic solution and reused. As a result, wasteful wastewater and waste are eliminated, and the process is closed.

2. Nickel hydroxide obtained In the nickel hydroxide thus obtained, as shown in the photograph of FIG. 2, a large number of primary particles of nickel hydroxide are aggregated to form secondary particles of nickel hydroxide.

The primary particles of nickel hydroxide may be spherical, scaly, or prismatic, but are not particularly constant. When the particle size of the secondary particles is confirmed by SEM observation, it is as large as 3 to 200 μm, and the specific surface area determined by the BET method is 10 to ²⁰⁰ m ² / g. In addition, the content of impurity elements such as sodium is very low and the purity is high. Specifically, the content of each element of Cr, Fe, Si, Co, Ca, Na, Zr, P, Mn is less than 10 mass ppm of the lower limit of analytical quantification, the content of Cl is less than 50 mass ppm, The sulfur content is less than 1 ppm by mass, and these elements do not exceed the lower limit of quantification. In the present invention, the secondary particles preferably have a particle size of 5 to 100 μm and a specific surface area of 20 to 180 m ² / g.

3. Manufacture of nickel oxide The nickel hydroxide obtained after the filtration is dried and roasted in an oxidizing atmosphere to obtain nickel oxide.

  The drying conditions are not particularly limited as long as moisture can be evaporated, and it is efficient to heat to 80 ° C. or higher. At that time, an inert gas such as nitrogen gas, helium, or argon may be circulated or decompressed. The oxidizing atmosphere is a gas containing 5% or more of oxygen, and includes a mixed gas containing nitrogen, carbon dioxide, etc. in addition to oxygen, such as the atmosphere.

Although the temperature conditions at the time of roasting are not particularly limited, H ₂ O, CO ₂ , NO, and NO ₂ are generated and discharged from the nickel hydroxide secondary particles by setting the temperature to 600 ° C. or higher. Further, when nickel hydroxide is roasted at 800 to 1000 ° C. at a higher temperature, the remaining chlorine component is evaporated, and high-purity nickel oxide is easily obtained. If it is less than 800 degreeC, there are many residual chlorines and crystallinity may also become low. Moreover, when it exceeds 1000 degreeC, although roasting time may be shortened, there exists a problem which a primary particle generally coarsens, and 850-1000 degreeC is more preferable. The roasting time is not particularly limited, but can be 1 to 5 hours, preferably 1 to 3 hours. NOx generated from the roasting process is reduced and detoxified by the hydrogen discharged from the electrolytic cell.

The particle diameter of the nickel oxide obtained varies depending on the form of nickel hydroxide, roasting conditions, and the like, and thus cannot be specified unconditionally, but the average particle diameter of the primary particles is 0.1 to 2.0 μm. A preferable average particle diameter of nickel oxide is 0.3 to 1.5 μm. When the particle size is too large, nickel oxide fine powder can be obtained through a pulverization step using a pulverizer.
The nickel oxide thus obtained has high crystallinity, very little impurity metals and sulfur, and chlorine can be 300 ppm by mass or less. If there are very few impurity metals and sulfur and chlorine is 50 mass ppm or less, it is preferably used as an electrode material for a fuel cell such as a solid oxide fuel cell (SOFC).

  EXAMPLES Hereinafter, although this invention is demonstrated using an Example, this invention is not limited only by an Example.

Example 1
<Experiment 1>
A nickel plate having a purity of 3N (50 × 50 × 2 mm) is attached to the anode, and a titanium plate (25 × 25 × 1 mm) is attached to the cathode, and ammonium nitrate (0.4 mol / l) and ammonium chloride (0. 12 mol / l) was charged at 500 ml. Next, electrolysis was performed at an anode current density of 5 A / dm ² for 3 hours to produce nickel hydroxide. The cell voltage at this time was 6V, and pH was 8-9. The liquid temperature started from 30 ° C., and the liquid temperature after 3 hours of electrolysis is summarized in Table 1.
Nickel hydroxide precipitated by electrolysis was filtered by suction filtration, washed with pure water until the electrical conductivity of the filtrate reached 1 mS / cm, and dried in an oven at a set temperature of 100 ° C. The particle shape of the obtained nickel hydroxide powder (sample a) was observed with an electron microscope (SEM) as shown in FIG. The amount of impurities is measured for elements of S, Cl, Cr, Fe, Si, Co, Ca, Na, Zr, P, and Mn, and S is infrared spectroscopic analysis and ICP (Inductively Coupled Plasma) emission spectroscopic analysis, Cl was analyzed by fluorescent X-ray analysis, Na was analyzed by atomic absorption, and other elements were analyzed by ICP emission spectroscopy. As a result, as shown in Table 1, impurity metals other than nickel, such as Cr, Fe, Co, Ca, Na, Zr, and Mn, were less than the lower limit of determination of 10 ppm, and sulfur was less than 1 mass ppm. Further, when X-ray diffraction measurement (XRD) of the nickel hydroxide powder was performed, a peak of Ni (OH) ₂ was confirmed in the chart as shown in FIG.

<Experiment 2>
Electrolysis was performed under the same conditions as in <Experiment 1> except that ammonium nitrate was changed to 1 mol / l and ammonium chloride was changed to 0.3 mol / l to obtain nickel hydroxide (sample b). As shown in Table 1, the amount of impurities in the obtained nickel hydroxide was less than the lower limit of quantification of metals other than nickel.

<Experiment 3>
Electrolysis was performed under the same conditions as in <Experiment 1> except that ammonium nitrate was changed to 1 mol / l and ammonium chloride was changed to 0.5 mol / l to obtain nickel hydroxide (sample c). As shown in Table 1, the amount of impurities in the obtained nickel hydroxide was less than the lower limit of quantification of metals other than nickel.

<Experiment 4>
Electrolysis was carried out under the same conditions as in <Experiment 1> except that the anode current density was 15 A / dm ² to obtain nickel hydroxide. As shown in Table 1, the amount of impurities in the obtained nickel hydroxide (sample d) was less than the lower limit of quantification for metals other than nickel.

<Experiment 5>
Electrolysis was performed under the same conditions as in <Experiment 1> except that the cathode was a platinum clad plate (25 × 25 × 1 mm) to obtain nickel hydroxide (sample e). As shown in Table 1, the amount of impurities in the obtained nickel hydroxide was less than the lower limit of quantification of metals other than nickel.

<Experiment 6>
Electrolysis was performed under the same conditions as in <Experiment 1> except that the cathode was a nickel plate (25 × 25 × 13 mm), the ammonium nitrate concentration was 0.6 mol / l, and ammonium chloride was 0.12 mol / l. Sample f) was obtained. As shown in Table 1, the amount of impurities in the obtained nickel hydroxide was less than the lower limit of quantification of metals other than nickel.

<Experiment 7>
Electrolysis was performed under the same conditions as in <Experiment 6> except that the cathode was a SUS316 plate (25 × 25 × 1 mm) to obtain nickel hydroxide (sample g). As shown in Table 1, the amount of impurities in the obtained nickel hydroxide was less than the lower limit of quantification of metals other than nickel.

(Comparative Example 1)
The electrolysis was performed under the same conditions as in Example 1 <Experiment 1> except that ammonium chloride was not added to the electrolytic solution. However, nickel metal was not dissolved and nickel hydroxide was not obtained.

(Comparative Example 2)
According to the example of Patent Document 3, an electrolytic cell was prepared, and electrolytic brine consisting of 44.6 g / l sodium chloride and 2.6 g / l ammonia was introduced through the supply pipe at 48 g per hour. The pH value was adjusted so that the electrolytic brine was 10.3 at a temperature of 55 ° C. by introducing a 1 mol / l sodium hydroxide solution from the supply pipe. A nickel anode and a nickel cathode having an electrode area of 400 cm ² were used as electrodes, and electrolysis was performed at a current density of 1000 A / m ² while circulating 2.3 liters of electrolytic brine in an electrolytic cell.
The nickel hydroxide obtained is first washed with completely deionized water, then washed with 1 mol / l sodium hydroxide solution and again with completely deionized water, at an air circulating oven at a temperature of 70 ° C. And dried. This gave nickel hydroxide with a time yield of 76 g. When the SEM photograph of the obtained nickel hydroxide powder was viewed, the particle shape was spherical and the particles were not bonded to each other. The specific surface area was not measured due to the high Na content.
As a result of analyzing the obtained nickel hydroxide (sample h), the product was 57.5 wt% nickel, 17 mass ppm sodium, 300 mass ppm chlorine, and 40 mass ppm ammonia or less.

"Evaluation"
From the above results, in Example 1, an electrolytic solution containing a specific ammonium compound was electrolyzed by using the method of the present invention, and high purity metallic nickel was used as an anode electrode. When observed with an electron microscope (SEM), voids were formed between the large secondary particles of nickel hydroxide, and the filterability was high. Moreover, although a trace amount chlorine is contained as an impurity, as shown in Table 1, metals other than nickel were less than the lower limit of quantification.

  On the other hand, in Comparative Example 1, since the electrolytic solution did not contain ammonium halide, nickel hydroxide was not deposited. In Comparative Example 2, since the electrolytic solution was a solution containing aqueous ammonia and sodium chloride, the resulting nickel hydroxide powder had a spherical particle shape, the particles were not bonded to each other, and the filterability was very high. It was bad. Further, as shown in Table 1, the amount of impurities contained sodium derived from the electrolyte at a high concentration.

(Example 2)
<Experiment 8>
Nickel hydroxide (sample a) obtained in <Experiment 1> of Example 1 was baked in the atmosphere at 800 ° C. for 2 hours to be crushed to obtain nickel oxide (sample i). The amount of chlorine in the obtained nickel oxide was less than 50 ppm by mass. Further, when X-ray diffraction measurement (XRD) of the nickel oxide powder was performed, only the NiO peak was observed as shown in FIG.
In addition, the impurity analysis of nickel oxide is measured for elements of S, Cl, Cr, Fe, Si, Co, Ca, Na, Zr, P, and Mn, S is infrared spectroscopic analysis and ICP emission spectroscopic analysis, and Cl is X-ray fluorescence analysis, Na for atomic absorption analysis, and other elements for ICP emission spectroscopic analysis.

<Experiment 9>
Nickel hydroxide (sample a) obtained in <Experiment 1> of Example 1 was baked in the atmosphere at 850 ° C. for 2 hours and crushed to obtain nickel oxide (sample j). The amount of chlorine in the obtained nickel oxide was less than 50 ppm by mass.

<Experiment 10>
Nickel hydroxide (sample a) obtained in <Experiment 1> of Example 1 was baked and pulverized in the atmosphere at 950 ° C. for 2 hours to obtain nickel oxide (sample k). The amount of chlorine in the obtained nickel oxide was less than 50 ppm by mass.

(Comparative Example 3)
Nickel hydroxide (sample h) obtained in Comparative Example 2 was baked and crushed at 800 ° C. for 2 hours in the air to obtain nickel oxide. The obtained nickel oxide (Sample 1) had a sodium content of 21 mass ppm, a sulfur content of 2 mass ppm, and a chlorine content of 70 mass ppm.

"Evaluation"
From Table 2 showing the above results, in Example 2, since nickel hydroxide powder (Example 1) obtained by the method of the present invention was roasted in an oxidizing atmosphere, Ni (OH) observed in the nickel hydroxide powder was observed. ) The heterophasic peaks other than the peak ₂ disappeared, and nickel oxide powder with high crystallinity was obtained. Such nickel oxide powder can be expected to have sufficient electrical characteristics as an electrode material for a fuel cell.
In contrast, in Comparative Example 3, since nickel hydroxide powder (Comparative Example 2) obtained using electrolytic brine containing sodium chloride was roasted in an oxidizing atmosphere, nickel oxide containing sodium at a high concentration was used. It became powder. With such nickel oxide powder, it is not possible to expect electrical characteristics required as an electrode material for a fuel cell.

(Example 3)
<Experiment 11>
Nickel hydroxide obtained in the same manner as in <Experiment 1> in Example 1 was roasted and crushed in the same manner as in <Experiment 10> in Example 2 except that the electrolysis time was 15 hours. (Sample m). When the particle size distribution of the obtained nickel oxide was measured with a wet particle size distribution meter, the value of D50 was 1.2 μm.
In addition, when the particle size distribution of the nickel oxide (sample k) obtained in <Experiment 8> was measured with a wet particle size distribution meter, the value of D50 was 0.3 μm.

"Evaluation"
From Table 3 showing the above results, it can be seen that in Example 3, the particle size of the nickel oxide powder obtained by the method of the present invention can be controlled by the time for electrolysis. Such a method for producing nickel oxide powder can be said to be an extremely effective means for producing electrode materials for fuel cells.

  The nickel hydroxide and nickel oxide obtained by the present invention can be widely used as a raw material for a positive electrode material for a secondary battery such as a nickel metal hydride battery or a lithium ion battery, or an electrode material for a solid oxide fuel cell. It can also be used as a component material for hybrid cars, electric cars, and new power generation systems that replace nuclear power generation, and its industrial value is extremely high.

1 Electrolyzer 2 Anode 3 Cathode 4 Electrolyte

According to the seventh aspect of the present invention, in any one of the first to sixth aspects, the content of any component of Cr, Fe, Si, Co, Ca, Na, Zr, P, and Mn is 10 There is provided nickel hydroxide having a mass of less than ppm, a chlorine content of less than 0.5 mass% , and a sulfur content of less than 1 mass ppm.

  On the other hand, according to the ninth invention of the present invention, in the seventh or eighth invention, it is obtained by roasting nickel hydroxide in an oxidizing atmosphere at a temperature range of 800 to 1000 ° C., and Cr, Fe, Si , Co, Ca, Na, Zr, P, and Mn are contained in less than 10 ppm by mass, and the chlorine content is less than 50 ppm by mass, and the sulfur content is less than 1 ppm by mass. Nickel is provided.

The primary particles of nickel hydroxide may be spherical, scaly, or prismatic, but are not particularly constant. When the particle size of the secondary particles is confirmed by SEM observation, it is as large as 3 to 200 μm, and the specific surface area determined by the BET method is 10 to ²⁰⁰ m ² / g. In addition, the content of impurity elements such as sodium is very low and the purity is high. Specifically, the content of each element of Cr, Fe, Si, Co, Ca, Na, Zr, P, and Mn is less than 10 mass ppm of the lower limit of analysis determination, and the content of Cl is 0.5 mass%. The sulfur content is less than 1 ppm by mass, and these elements never exceed the lower limit of quantification. In the present invention, the secondary particles preferably have a particle size of 5 to 100 μm and a specific surface area of 20 to 180 m ² / g.

Claims (10)

  An anode and a cathode are installed in the electrolytic cell, metallic nickel is set as the anode side, a mixed solution of ammonium nitrate and ammonium halide is charged as an electrolytic solution, and electrolysis is performed at a pH of 6 or more to generate a nickel ammine complex, which is saturated. A nickel hydroxide production method, wherein the nickel ammine complex is precipitated as particulate nickel hydroxide.   2. The hydroxide according to claim 1, wherein one metal selected from the group consisting of platinum, titanium, titanium-plated titanium, clad of titanium and platinum, nickel, and stainless steel is used as the cathode. Nickel manufacturing method.   The method for producing nickel hydroxide according to claim 1, wherein the ammonium nitrate concentration is 0.1 to 5.0 mol / l.   The method for producing nickel hydroxide according to any one of claims 1 to 3, wherein the ammonium halide concentration is 1.0 mol / l or less.   The method for producing nickel hydroxide according to claim 1, wherein the ammonium halide is ammonium chloride.   The pH of an electrolytic cell is the range of 6-9, The manufacturing method of the nickel hydroxide in any one of Claims 1-5 characterized by the above-mentioned.   It is obtained by the method according to any one of claims 1 to 6, and any component of Cr, Fe, Si, Co, Ca, Na, Zr, P, Mn is less than 10 mass ppm, and chlorine The nickel hydroxide whose content is less than 50 mass ppm and whose sulfur content is less than 1 mass ppm. The nickel hydroxide according to claim 7, wherein the average particle diameter is 3 to 200 μm and the specific surface area is 10 to 200 m ² / g.   The nickel hydroxide according to claim 7 or 8 is obtained by roasting in a temperature range of 800 to 1000 ° C in an oxidizing atmosphere, and is made of Cr, Fe, Si, Co, Ca, Na, Zr, P, Mn. Nickel oxide whose content is less than 10 ppm by mass, chlorine content is less than 50 ppm by mass, and sulfur content is less than 1 ppm by mass.   The nickel oxide according to claim 9, wherein the nickel oxide is used as an electrode material of a solid electrolyte fuel cell.

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