JPH11312519A - Compound nickel hydroxide active material containing mn, and preparation thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a superior discharging characteristic, in particular for improving the utilization factor, when used for an electrode material of a secondary battery. SOLUTION: In this active material, tapped density is set to 1.9 g/cc or more, a specific surface area is set to be 8 m<2> /g or more, space volume of pores is made to be 0.01 cm<3> /g or more, pore volume of pores having 30 Å or more of pore radius is made to be 40% or less with respect to total pore volume, a Mn content is made to be within a range from 5 mol.% or more to 15 mol.% or less, and an average oxidation number of Mn is made to be 3.5 or higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a Mn-containing composite nickel hydroxide active material and a method for producing the same.

[0002]

2. Description of the Related Art A nickel hydroxide positive electrode commonly used in alkaline storage batteries such as nickel-cadmium storage batteries and nickel-metal hydride storage batteries is required to have a high energy density. In the course of the increase, the paste type capable of increasing the capacity density has been mainly used instead of the conventional sintered type. This paste-type nickel positive electrode is obtained by filling nickel hydroxide powder together with a cobalt compound powder and the like into a foamed nickel substrate or nickel fiber substrate having a high porosity of about 95%, followed by pressure molding. Such a foamed nickel substrate is obtained by plating nickel on a foamed plastic such as urethane and then heating it to thermally decompose the foamed plastic to obtain a foamed metal.

The reaction during charging and discharging of nickel hydroxide, which is a positive electrode material for an alkaline storage battery, generally involves β-Ni (OH) ₂
And β-NiOOH, which is a one-electron reaction, but the most stable reaction, and is widely used. If this is made a multi-electron reaction by utilizing the reaction between β-Ni (OH) ₂ and γ-NiOOH, there is an advantage that the capacity is increased. However, β-Ni (OH) ₂ and γ
Γ generated during charge / discharge due to the lattice constant difference of NiOOH
There is a problem that a discharge reaction from -NiOOH to β-Ni (OH) ₂ is difficult.

On the other hand, when utilizing the reaction between α-Ni (OH) ₂ and gamma-NiOOH, which also has the advantage that capacitance increases because it is a multi-electron reaction, and α-Ni (OH) ₂ and γ-NiOOH is preferable because the difference in lattice constant is small so that the volume change during charging and discharging is small.

[0005] However, α-Ni (OH) ₂ is unstable in an alkaline solution and has a problem that it is easily changed to β-Ni (OH) ₂ , which has been a cause that it cannot be put to practical use.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a nickel hydroxide active material having excellent discharge characteristics, particularly improved utilization when used as a battery electrode material, and a method for producing the same. And

[0007]

Means for Solving the Problems According to the invention of claim 1 which achieves the above object, the tap density is not less than 1.9 g / cc and the content of Mn is not less than 5 mol% and not more than 15 mol%. Wherein the tetravalent Mn is at least 50% by weight of the total Mn content and the average degree of oxidation of Mn is at least 3.5.

[0008] In a second aspect of the present invention, in the first aspect, the specific surface area is at least 8 m ² / g and the spatial volume of the pores is
The pore volume is 0.01 cm ³ / g or more, and the pore volume having a pore radius of 30 ° or more is 40% or less of the total pore volume.

The invention of claim 3 is characterized in that, in claim 1 or 2, the nickel hydroxide producing step is performed in an inert gas atmosphere.

[0010] The invention of claim 4 is to continuously supply an Ni salt solution containing Mn, an aqueous alkali solution and an aqueous solution containing ammonium ions into a sealed reaction vessel and continuously grow the composite hydroxide. In the method for producing a Mn-containing composite nickel hydroxide to be extracted to Mn, Mn contained in the nickel hydroxide is synthesized in a divalent state, and then M
It is characterized in that the n-containing composite nickel hydroxide is dried and oxidized in the air or oxygen atmosphere.

The invention of claim 5 is the invention according to claim 4, wherein the dissolved oxygen concentration in the solution in the closed tank is 0.5 mg / L.
It is characterized by being synthesized below.

[0012] The invention of claim 6 is characterized in that, in claim 4 or 5, the synthesis is performed in an inert gas atmosphere.

The invention according to claim 7 is the invention according to claims 4 to 6, wherein the average residence time in the tank is 3 hours or more and 12 hours or less, and the solution pH in the tank is 12 or more and 13.5 or less;
The reaction is performed at a reaction temperature of 25 ° C. or more and 40 ° C. or less in the tank.

The invention of claim 8 is the invention according to claims 4 to 7, wherein the drying temperature is 70 ° C. or more and the drying time is 16 hours.
It is longer than an hour.

The invention of claim 9 is the invention according to claims 4 to 8, wherein the Mn-containing composite nickel hydroxide is in a eutectic state and / or
Alternatively, it is characterized by being in a solid solution state.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

The Mn-containing composite nickel hydroxide active material of the present invention has a tap density of 1.9 g / cc or more, an Mn content of 5 mol% to 15 mol%, and a tetravalent Mn content. Is 50% by weight or more of the total Mn amount, and the average degree of oxidation of Mn is 3.5 or more.

The Mn-containing composite nickel hydroxide active material further has a specific surface area of 8 m ² / g or more, a pore volume of 0.01 cm ³ / g or more, and a pore size of 30 ° or more. The pore volume having a radius is 40% or less of the total pore volume.

In the method for producing an active material of the present invention, a Ni salt solution containing Mn, an alkaline aqueous solution and an aqueous solution containing ammonium ions are continuously supplied into a closed reaction vessel, and the grown composite hydroxide is continuously supplied. In the method for producing a Mn-containing composite nickel hydroxide to be extracted, Mn contained in the nickel hydroxide is synthesized in a divalent state, and then the extracted Mn-containing composite nickel hydroxide is dried in an air or oxygen atmosphere, It oxidizes.

Here, in the present invention, for example, sulfates, nitrates, chlorides and the like are used as Ni salts, and chlorides, sulfates and the like are used as Mn salts. The alkaline aqueous solution is not particularly limited, but it is preferable to use sodium hydroxide.

The nickel hydroxide synthesizing tank used in the present embodiment is preferably one in which the inside is sealed.
Before and during the synthesis of nickel hydroxide, an inert gas and a reducing gas are introduced, and the dissolved oxygen concentration in the solution in the tank is reduced to 0.
The synthesis is performed under the condition of 5 mg / L or less. This is because, when the dissolved oxygen concentration exceeds 0.5 mg / L, an oxidation reaction occurs during the synthesis, which is not preferable. As the inert gas to be introduced, for example, argon, nitrogen, helium or the like is used, and the concentration of dissolved oxygen is bubbled in the tank.
Do not exceed 0.5 mg / L.

Here, in the production of the Mn-containing composite nickel hydroxide active material, Mn2 is synthesized by synthesizing in the nickel hydroxide synthesis tank under an inert gas atmosphere.
It can be contained in a valence state. Then, by oxidizing to trivalent and tetravalent by an oxidation reaction, it is possible to obtain one in which tetravalent Mn is 50% by weight or more of the total Mn amount and the average degree of oxidation of Mn is 3.5 or more. it can.

It is preferable to continuously supply a Ni salt solution containing Mn, an aqueous alkali solution and an aqueous solution containing ammonium ions into the reaction tank. Here, the ratio of Ni / Mn is 95/5 to 85/15, for example, an aqueous solution of Ni / Mn sulfate adjusted to 1.75 mol / L is used, and the aqueous ammonia solution is, for example, 6.5 mol / L. As the aqueous ammonia solution and the aqueous alkaline solution, it is preferable to use a 6 mol / L aqueous sodium hydroxide solution, but the present invention is not limited thereto.

The supply of the Ni salt solution containing Mn is preferably at a rate of 5.0 to 18 ml / min, preferably 10 ml / min, and the supply of the ammonia solution is 3.0 to 11 ml / min, preferably A good speed is 6.2 ml. This is because when the supply speed is low, as described later, the specific surface area is small,
In addition, the average degree of oxidation of Mn after drying is reduced to 3.1, which is not preferable. Also, if the supply rate is high, as described later, it becomes unreacted by aggregates of fine particles, which is not preferable. The average residence time is preferably 3 hours or more and 12 hours or less, although it depends on the supply speed.

Preferably, the Ni salt solution containing Mn and the ammonia solution are supplied simultaneously. This is because, if they are not supplied at the same time, the crystal nucleus generation speed, that is, the precipitation speed becomes extremely high, and the agglomeration state of the fine particles occurs, making it difficult to obtain a sufficient tap density.

The reaction is carried out while maintaining the reaction temperature at about 25 to 40 ° C., preferably around 30 ° C. this is,
When the temperature is 40 ° C., the specific surface area is small, which is not preferable. When the temperature is lower than 25 ° C., it becomes bulky, and both are not preferable.

It is preferable to carry out the reaction while maintaining the reaction pH at about 12 to 13.5, preferably around 12.5. This is because if the pH is less than 12, the tap density is low, and if the pH is 13.5 or more, the tap density is high but the specific surface area is small, which is not preferable.

The obtained nickel hydroxide is filtered, washed, dehydrated and dried. This drying step is performed in the atmosphere at 70 ° C. or higher, preferably 80 ° C., for at least 16 hours or longer, preferably for about one week (7 days). It will be oxidized.

The nickel hydroxide active material of the present invention obtained by such a method has a tap density of 1.9 g / cc or more, a specific surface area of 8 m ² / g or more, and a pore volume of space. 0.01 cm ³ / g or more, the pore volume having a pore radius of 30 ° or more is 40% or less with respect to the total pore volume, and the Mn content is 5 mol% or more and 15 mol% or less. Within the range, the average degree of oxidation of Mn has physical properties of 3.5 or more. Here, in the nickel hydroxide active material of the present invention, the content of Mn is in the range of 5 mol% or more and 15 mol% or less.
This is because the utilization rate is low. If it exceeds 15 mol%, the utilization rate is improved, but the tap density is low, which is not preferable.

The Mn-containing nickel hydroxide of the present invention is in a eutectic state and / or a solid solution state. Thus, the manganese atoms in the nickel hydroxide crystal are in the eutectic state and / or
Alternatively, the solid solution state is set because the mobility of protons moving in the crystal lattice during charge / discharge is improved, and the charge / discharge reaction proceeds quickly. In other words, if it is not in a solid solution state and is separated and precipitated, only nickel hydroxide participates in the reaction, and a sufficient utilization rate cannot be obtained, which is not preferable.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below, but the present invention is not limited to these embodiments.

<Example 1: Preparation of active material (with N ₂ gas)
Ni / Mn = 9/1 sulfate aqueous solution prepared to> 1.75 mol / L, 6.5 mol / L ammonia aqueous solution, 6 mol / L
L of sodium hydroxide aqueous solution was prepared. Nitrogen gas was bubbled into the tank at 1 liter per minute. The dissolved oxygen at this time was 0.2 mg / L. The Ni salt solution is added at
ml and an ammonia solution were simultaneously supplied into a 7.2 L reaction tank at a rate of 6.2 ml / min while maintaining the temperature at 30 ° C., and the mixture was stirred and mixed quickly and uniformly. While maintaining the temperature in the bath at 30 ° C., 6.2 mol / L of sodium hydroxide at an average rate of 6 mol / L was used.
The mixture was stirred while being supplied at such a speed as to maintain the pH in the reaction tank within the range of 12.5 ± 0.2. The amount of sodium hydroxide was 2.1 and the amount of ammonia was 2 with respect to a total amount of 1 of Ni and Mn salts. The produced composite hydroxide overflowed from the upper part of the reaction tank and was continuously taken out. The average residence time at this time was 6 hours. After operating continuously for 6 hours, a sample was collected, washed with water, and filtered to obtain green first particles (* 1). Mn at this time is not oxidized and contains divalent Mn. From the results of the quantitative analysis, the amount of manganese at this time was 10 mol% in metal atom ratio, which was consistent with the mixing ratio of the starting materials,
When the average valence of Mn was measured by the ferrous ammonium sulfate method, it was 2.0. This indicates that the Mn valence in the first particles obtained is divalent.

The first particles obtained above were placed in an atmosphere at 80 ° C. for 1 hour.
Drying was performed for a week to obtain brownish second particles (* 2). Mn at this time is easily oxidized and trivalent or tetravalent M
n. From the results of the quantitative analysis, the manganese content at this time was 10 mol% in terms of the metal atom ratio, which coincided with the mixing ratio of the starting materials. When the average valence of Mn was measured by the ammonium ferrous sulfate method, it was 3.7 there were. This shows that the Mn valence in the obtained second particles (* 2) includes a valence of 3 or more.

From the X-ray diffraction pattern, only the peak attributed to nickel hydroxide was observed, confirming that the crystal had a uniform composition. It was also confirmed from the SEM photograph that the particles were spherical particles having a uniform particle diameter. The tap density was determined by measuring the volume when 15 g of powder was put into a 20-ml measuring cylinder and tapped 1,000 times, and calculated by the formula of input weight / measured volume. As a result of this measurement, the tap density of the fine particle powder of this example was 2.2 g / cc. The specific surface area and the pore volume were measured by a nitrogen gas adsorption method, and the specific surface area was 16 m ^2.
/ G, the total pore volume is 0.023 cm ³ / g, and the ratio of the pore volume having a pore radius of 30 ° or more to the total pore volume is 30.
%Met.

<Comparative Example 1: Preparation of Comparative Active Material (No N ₂ Gas)> The operation was performed under the same conditions as in Example 1 except that nitrogen gas was not sent into the tank and the tank was opened to the atmosphere. At this time, the amount of dissolved oxygen in the tank was 5 mg / L. The brown third particles (* 3) after the washing and filtration were obtained. From the results of the quantitative analysis, the amount of manganese at this time was 10 mol% in terms of metal atom ratio, and the average valence of Mn was measured by the ammonium ferrous sulfate method.
3.5, which was not bulky but an aggregate of bulky fine particles. From this, it was found that the Mn valence in the obtained particles contained a valence of 3 or more. The tap density of the obtained fine particle powder was 1.2 g / cc. Further, peaks other than nickel hydroxide, which are considered to be impurities, were observed from the X-ray diffraction diagram.

<Quantitative Determination of Mn Trivalent and Tetravalent> Next, particles of nickel hydroxide, commercially available nickel hydroxide, and commercially available manganite (γ-MnO (OH): Mn has a trivalent oxidation number of 1)
0 g are dissolved in fixed amounts of concentrated hydrochloric acid and concentrated nitric acid. Table 1 shows the amounts of Mn and Ni obtained at this time.
For concentrated nitric acid, the dissolved solution was filtered to separate it from insoluble matter, and the Mn content and the Ni content in the filtrate were determined. In addition, the average valence of Mn was determined by the ammonium ferrous sulfate method for those separated by filtration. The results are also shown in Table 1.

[0037]

[Table 1]

In the dissolution of concentrated hydrochloric acid, all valences are 2
Dissolved as a valency, and the total amount of Mn is determined. In concentrated nitric acid dissolution, Mn divalent is dissolved, but Mn tetravalent is insoluble. Mn trivalent causes a disproportionation reaction, and Mn divalent and Mn4
Are generated in equal amounts. This is evident from the results of manganite in Table 1 in that the amount of Mn contained in the filtrate is half that of concentrated hydrochloric acid in concentrated nitric acid, and the insoluble matter filtered out has an average Mn oxidation degree of 4. is there. Furthermore, Ni does not depend on the type of acid, regardless of whether it contains Mn or not, and the measured values are equal.

In addition, the first of the Mn-containing nickel hydroxide particles
Particles (* 1) have the same value for both concentrated hydrochloric acid and concentrated nitric acid.
It turns out that it is contained by Mn divalent. In addition, it also agrees with the Mn average valence determined by the ammonium monosulfate method. Regarding the second particles (* 2) and the third particles (* 3), since the amount of Mn obtained by dissolving in concentrated nitric acid is half of the amount of trivalent Mn from the above results, concentrated hydrochloric acid is used. Table 2 shows the results obtained by calculating the amount of Mn tetravalent by the following formula (1) from the total Mn amount obtained as a result. Table 2 also shows the average oxidation number of Mn calculated from the trivalent Mn content and the tetravalent Mn content obtained by the ammonium ferrous sulfate method. Tetravalent Mn content in active material = Total Mn content determined by dissolving in concentrated hydrochloric acid-(Mn determined by dissolving in concentrated nitric acid
Amount x 2) ... (1)

[0040]

[Table 2]

From the results of "Table 2", the values were obtained from the two methods.
The average oxidation numbers obtained correspond to the second particles (* 2) and
Tri-particles (* 3) may contain trivalent and tetravalent Mn
Recognize. From these results, it was found that the method of Example 1
N as an inert gas _TwoDue to the action of gas, large
Before air drying, containing only divalent Mn, after oxidation by drying
Contains trivalent and tetravalent Mn. Therefore,
As in Comparative Example 1, trivalent, 4
Must be clearly different from those containing monovalent Mn
There was found.

Next, under the conditions of Example 1, a comparative test was performed for a case where the speed of the liquid to be supplied was changed, a case where the reaction temperature was changed, and a case where the speed of sending sodium hydroxide was changed. .

<Comparative Example 2> The operation was performed in the same manner as in Example 1 except that the supply rate of the liquid to be supplied into the tank was changed to one third of the condition in Example 1. The average residence time was 18 hours. The obtained fine particle powder had a small specific surface area of 6 m ² / g, and the average degree of oxidation of Mn after drying was as low as 3.1.

<Comparative Example 3> An operation was performed in the same manner as in Example 1 except that the supply rate of the liquid to be supplied into the tank was changed to 2.5 times the condition in Example 1. The average residence time was 2.4 hours. The obtained powder was an aggregate of fine particles, not spherical, and almost unreacted liquid overflowed from the upper part of the tank.

<Comparative Example 4> The same operation as in Example 1 was carried out except that the reaction temperature was changed to 50 ° C. The obtained powder had a small specific surface area of 5 m ² / g, and the pore volume having a pore radius of 30 ° or more was 70% of the total pore volume.

<Comparative Example 5> The same operation as in Example 1 was carried out except that the reaction temperature was changed to 20 ° C. The resulting powder was spherical, but bulky.

<Comparative Example 6> In Example 1, 6.0 mol
/ L sodium hydroxide aqueous solution was fed at a rate of 5.5 ml / min. The operation was carried out in the same manner as in Example 1 except that the average residence time was 6.5 hours and the solution pH was 11.5. The resulting powder had a specific surface area of 19 m ² / g but a tap density of 1.5 g / cc.
It was bulky.

<Comparative Example 7> 6.0 mol /
The same operation as in Example 1 was carried out except that 7.5 ml of L aqueous sodium hydroxide solution was fed per minute, the average residence time was 5.8 hours, and the solution pH was 13.7. The resulting powder had a high tap density of 2.3 g / cc, but a small specific surface area of 6 m ² / g.

The results of Example 1 and Comparative Examples 2 to 7 are shown in Table 3.

[0050]

[Table 3]

The effect on the amount of Mn added to the Ni salt solution will be described below. <Example 2> First, as [Example 2], the content of Mn with respect to the Ni salt solution was set to 5 mol%, synthesis was performed under the conditions of Example 1, and a model cell was fabricated in the same manner as in Example 2. The discharge capacity was determined. <Example 3> Further, as [Example 3], the content of Mn in the Ni salt solution was set to 15 mol%, particles were synthesized under the conditions of Example 1, and a model cell was fabricated in the same manner as in Example 2. To determine the discharge capacity. A porous nickel current collector was filled with 10 g of the particles (* 2) containing 10 mol% obtained in Example 1 in a paste state, and then dried and pressurized to produce a nickel electrode. A model cell was fabricated using a hydrogen storage alloy as a counter electrode and a 7.2 mol / L aqueous solution of potassium hydroxide as an electrolyte. Similarly, a model cell was produced using the particles of Example 2 and Example 3.

After charging for 18 hours at a current equivalent to 0.1 C,
The battery was discharged to 0.5 V at a current equivalent to 0.2 C to determine the discharge capacity. The theoretical discharge capacity during one-electron oxidation / reduction is 10
The value obtained by dividing the actually obtained discharge capacity as 0 was calculated as the discharge utilization rate. The discharge capacity, tap density, trivalent Mn content and tetravalent Mn content of the obtained particles, Mn average oxidation number and specific surface area determined by the ferrous ammonium sulfate method were determined. The Mn average oxidation number of the obtained particles according to Example 1 is
The total amount of trivalent Mn was 2.0%, the total amount of tetravalent Mn was 3.7%, and the ratio of tetravalent Mn to the total amount of Mn was 64.9%. The tap density is 2.2 g / c
c and the specific surface area was 15 m ² / g.

The average oxidation number of Mn of the obtained particles according to Example 2 was 3.6, the total amount of trivalent Mn was 1.1%, and the total amount of Mn of tetravalent was 1.7%. Tetravalent Mn
Accounted for 60.7%. The tap density is 2.
0 g / cc, and the specific surface area was 10 m ² / g.

The Mn average oxidation number of the obtained particles according to Example 3 was 3.7, the total trivalent Mn content was 2.6%, and the total tetravalent Mn content was 6.1%. Tetravalent Mn
Accounted for 70.1%. The tap density is 1.
It was 9 g / cc, and the specific surface area was 17 m ² / g.

<Comparative Example 9> Particles were synthesized under the conditions of Example 1 with the content of Mn in the Ni salt solution being 3 mol%, and a model cell was similarly prepared to determine the discharge capacity. Discharge utilization rate, tap density, trivalent M of the obtained particles
The amount of n and the amount of tetravalent Mn, the average oxidation number of Mn determined by the ferrous ammonium sulfate method, and the specific surface area were determined. The Mn average oxidation number of the obtained particles was 3.6, and the total amount of trivalent Mn was 0.7.
%, The total amount of tetravalent Mn was 1.0%, and the ratio of tetravalent Mn to the total amount of Mn was 58.8%. The tap density is 2.1 g / cc and the specific surface area is 10 m ² / g.
Met.

<Comparative Example 10> Particles were synthesized under the conditions of Example 1 with the content of Mn relative to the Ni salt solution being 20 mol%, and a model cell was similarly prepared to determine the discharge capacity. The discharge utilization factor, tap density, trivalent Mn amount and tetravalent Mn amount of the obtained particles, Mn average oxidation number and specific surface area determined by the ferrous ammonium sulfate method were determined. The Mn average oxidation number of the obtained particles is 3.7, and the total amount of trivalent Mn is 3.
5%, the total amount of tetravalent Mn was 8.0%, and the ratio of tetravalent Mn to the total amount of Mn was 69.5%. The tap density is 1.4 g / cc and the specific surface area is 12 m ² /
g.

<Comparative Example 1: Mn during formation of nickel hydroxide
Effect of valence> Using the particles of Comparative Example 1, a model cell was similarly prepared, and the discharge capacity was determined. The discharge utilization factor, tap density, trivalent Mn amount and tetravalent Mn amount of the obtained particles, Mn average oxidation number and specific surface area determined by the ferrous ammonium sulfate method were determined. The average oxidation number of Mn of the obtained particles was 3.5, the total amount of trivalent Mn was 3.0%, and the total amount of tetravalent Mn was 2.7.
%, And the ratio of tetravalent Mn to the total Mn amount is
47.4%. The tap density was 1.2 g / cc, and the specific surface area was 4.5 m ² / g.

<Example 4: Effect of the amount of tetravalent Mn contained in the nickel hydroxide after drying>
The synthesis was performed at a drying temperature of 110 ° C. Similarly, a model cell was prepared from the obtained particles, and the discharge capacity was determined. The average oxidation number of Mn of the obtained particles is 3.8, the total amount of trivalent Mn is 1.1%, the total amount of tetravalent Mn is 4.5%, and the ratio of tetravalent Mn to the total Mn amount is 80.3%. The tap density is 2.2 g / cc and the specific surface area is 17 g / cc.
m ² / g.

<Comparative Example 11: Effect of the amount of tetravalent Mn contained in dried nickel hydroxide> In Example 1, the drying temperature was 60 ° C. For the obtained particles, a model cell was prepared in the same manner as in Example 2 to determine the discharge capacity. The average oxidation number of Mn of the obtained particles was 3.2 and 3
The total Mn content of tetravalent is 4.4%, the total Mn content of tetravalent is 1.2%, and the ratio of tetravalent Mn to the total Mn content is 21.4%.
Met. The tap density was 2.2 g / cc and the specific surface area was m ² / g.

Examples 1 to 4 and Comparative Examples 9, 1, 1
Tables 4 and 5 show the results.

[0061]

[Table 4]

<Comparative Example 12> Drying was performed at 80 ° C in a vacuum in the same manner as in Example 1.

<Comparative Example 13> The drying temperature in Example 3 was set to 60
° C.

In Example 1, the average degree of oxidation with respect to the drying temperature was measured in the same manner. FIG. 1 shows the results together with the results of Example 4, Comparative Example 12, and Comparative Example 13. As shown in FIG. 1, it was found that the oxidation degree of the comparative example did not reach the specified value.

[0065]

As described above, according to the present invention, Mn is not oxidized in the synthesis reaction, but is dissolved in nickel hydroxide in a divalent state without being oxidized, and then oxidized when dried in air. By setting the oxidation number to 3.5 or more, even if γ-NiOOH is generated due to overcharging, β-Ni
It can return to (OH) ₂ and has a high utilization factor, and when used as an electrode material for a secondary battery, excellent discharge characteristics, particularly an improvement in utilization factor, can be achieved.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the number of dry days and the average manganese oxidation number.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Yasuhiro Ochi 1-5-1, Shiomachi, Takehara-shi, Hiroshima Prefecture Battery Materials Research Laboratories, Mitsui Kinzoku Mining Co., Ltd. (72) Takashi Okito 1-5, Shiomachi, Takehara-shi, Hiroshima Prefecture No. 1 Mitsui Kin Mining Co., Ltd. Battery Materials Research Laboratory

Claims (9)

[Claims] (1) a tap density of 1.9 g / cc or more;
n is in the range of 5 mol% to 15 mol%, and tetravalent Mn is 50% by weight or more of the total Mn amount;
n having an average degree of oxidation of 3.5 or more.
Containing composite nickel hydroxide active material. 2. The method according to claim 1, wherein the specific surface area is 8 m ² / g or more, and the space volume of the pores is 0.0.
A Mn-containing composite nickel hydroxide active material, having a pore volume of 1 cm ³ / g or more and a pore radius having a pore radius of 30 ° or more with respect to the total pore volume of 40% or less. 3. The Mn-containing composite nickel hydroxide active material according to claim 1, wherein the nickel hydroxide generation step is performed in an inert gas atmosphere. 4. A Mn-containing composite hydroxide that continuously supplies a Ni salt solution containing Mn, an alkaline aqueous solution, and an aqueous solution containing ammonium ions into a sealed reaction vessel and continuously removes the grown composite hydroxide. A method for producing nickel, characterized in that Mn contained in nickel hydroxide is synthesized in a divalent state, and then the extracted Mn-containing composite nickel hydroxide is dried and oxidized in air or an oxygen atmosphere. Method for producing a composite nickel hydroxide active material. 5. The method for producing a Mn-containing composite nickel hydroxide active material according to claim 4, wherein the compound is synthesized at a dissolved oxygen concentration of 0.5 mg / L or less in a closed tank solution. 6. The method for producing a Mn-containing composite nickel hydroxide active material according to claim 4, wherein the synthesis is performed in an inert gas atmosphere. 7. The method according to claim 4, wherein the average residence time in the tank is 3 hours or more and 12 hours or less,
A method for producing a Mn-containing composite nickel hydroxide active material, characterized in that the solution pH in the tank is 12 or more and 13.5 or less and the reaction temperature in the tank is 25 ° C or more and 40 ° C or less. 8. The method for producing a Mn-containing composite nickel hydroxide active material according to claim 4, wherein the drying temperature is 70 ° C. or more and the drying time is 16 hours or more. 9. The method for producing a Mn-containing composite nickel hydroxide active material according to claim 4, wherein the Mn-containing composite nickel hydroxide is in a eutectic state and / or a solid solution state.