JPH09219191A - Nickel electrode for alkaline storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve conductivity, charging/discharging capacity, and a cycle characteristic, by mixing two particles, having the main bodies of nickel hydroxide and cobalt-containing oxy-nickel hydroxide. SOLUTION: Cobalt-containing oxy-nickel hydroxide B is obtained, by dipping nickel particle hydroxide A containing cobalt into a potassium peroxodisulfide aqueous solution and drying it. NaOH aqueous solution is dropped, in suspending the nickel B and the particle A into a cobalt sulfate aqueous solution, and stirring, to deposit cobalt hydroxide of bivalent cobalt on a surface, to obtain positive electrode active material. An positive electrode 1, wherein a foaming metallic porous body is filled with paste using the active material, and a negative electrode 2, wherein paste, using hydrogen storage alloy, is applied to a punched metallic core body, are wound spirally via separator 3. The electrodes 1 and 2 are inserted in a battery can 4, therein to inject an alkaline electrolyte, then to be sealed. This restrains the increase of remaining capacity in the negative electrode, to improve conductivity, charging/discharging capacity, and a cycle characteristic.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel electrode for an alkaline storage battery used in an alkaline storage battery such as a nickel-cadmium storage battery or a nickel-hydrogen storage battery, and in particular to obtain an alkaline storage battery having a high capacity and excellent cycle characteristics. The present invention relates to a nickel electrode for alkaline storage batteries.

[0002]

2. Description of the Related Art Conventionally, nickel hydroxide Ni (OH) ₂ is generally used as a positive electrode material in alkaline storage batteries such as nickel-cadmium storage batteries and nickel-hydrogen storage batteries.
Was widely used.

However, since the nickel hydroxide itself has low conductivity, when it is used for the positive electrode, the nickel hydroxide is impregnated into a base body obtained by sintering metal nickel powder, or the nickel hydroxide is electrically conductive. Agents were being added.

When nickel hydroxide is impregnated into a substrate obtained by sintering metal nickel powder, the porosity of this sintered substrate is low and a sufficient amount of nickel hydroxide cannot be filled. There is a problem in that high energy cannot be obtained. Therefore, generally, foamed metal or metal felt has been filled with nickel hydroxide and a conductive agent and used as a positive electrode.

Further, cobalt hydroxide Co (OH) ₂ having divalent cobalt is conventionally used as one of the conductive agents added to nickel hydroxide, and the cobalt hydroxide itself has low conductivity. , 3 obtained by oxidizing this
Since the cobalt oxyhydroxide CoOOH having a high valency has high conductivity, the cobalt hydroxide is oxidized into a state of cobalt oxyhydroxide and added as a conductive agent.

Here, in the case of adding cobalt oxyhydroxide obtained by oxidizing cobalt hydroxide as a conductive agent to nickel hydroxide, conventionally, JP-A-62-234 has been used.
As disclosed in Japanese Patent No. 867 and Japanese Patent Application Laid-Open No. 62-237667, an electrode in which cobalt hydroxide is added to nickel hydroxide powder is incorporated into a battery, and charging is performed in this state to electrochemically react with cobalt hydroxide. Or by adding cobalt hydroxide to nickel hydroxide and oxidizing this cobalt hydroxide with an oxidizing agent in this state, as disclosed in JP-A-4-26058 and the like. As disclosed in Japanese Patent Application Laid-Open No. 64-81170, a method of depositing cobalt oxyhydroxide by charging / discharging an electrode plate filled with nickel hydroxide in an alkaline solution containing a cobalt complex, etc. has been carried out. It was

However, as described above, the electrode prepared by adding cobalt hydroxide to nickel hydroxide powder is incorporated into a battery for charging, and the cobalt hydroxide is oxidized to cobalt oxyhydroxide. There is a problem that the charge depth on the negative electrode side is increased by the charged capacity, and the usable charge / discharge capacity of the negative electrode is reduced, thereby shortening the cycle life as a storage battery.

When cobalt hydroxide added to nickel hydroxide is oxidized by an oxidant, the oxidant remains as an impurity, and the nickel hydroxide having the oxidant thus remains in the electrode of the storage battery. When used, there was a problem that the residual oxide was dissolved out in the battery to oxidize the negative electrode and the like, and the ions of the oxidizing agent adversely affected the characteristics of the storage battery. Further, when using an oxidizing agent in this manner, divalent cobalt (hereinafter referred to as divalent cobalt) made of cobalt hydroxide is oxidized, but an oxidizing agent that does not oxidize divalent nickel is used.
Nickel hydroxide was also oxidized and its crystal structure was destroyed, and when this was used as a positive electrode material in a storage battery, there was a problem that its charge / discharge capacity decreased and a sufficient amount of charge / discharge could not be performed. .

When the electrode plate filled with nickel hydroxide is charged and discharged in an alkaline solution containing a cobalt complex to precipitate cobalt oxyhydroxide, a sintered substrate is used as the substrate impregnated with nickel hydroxide. As described above, there is a problem that it is impossible to fill the sintered substrate with a sufficient amount of nickel hydroxide, and it becomes impossible to obtain high energy. When a substrate such as foam metal or punching plate is used instead of the sintered substrate and nickel hydroxide is highly filled, the cobalt compound does not fully penetrate into the inside of the electrode and precipitates only on the surface. Do it
The nickel hydroxide particles cannot be sufficiently covered with cobalt oxyhydroxide, so that sufficient conductivity is not imparted, the utilization rate of nickel hydroxide decreases, and a sufficient amount of charge / discharge cannot be performed. There was a problem.

Further, since the solubility of the cobalt compound in the alkaline solution is low, when a large amount of cobalt oxyhydroxide is added to the electrode, a large amount of alkaline solution containing a cobalt complex must be used. The waste liquid treatment of such an alkaline solution remaining after the addition has been a problem.

Further, if the above-mentioned electrode plate is charged and discharged without applying pressure, γ-NiOOH, which is poor in reversibility of charging and discharging, is likely to be generated, the utilization rate of nickel hydroxide is lowered, and sufficient charging and discharging is performed. There was also the problem of being unable to do it.

[0012]

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned various problems in the nickel electrode for alkaline storage batteries used as the positive electrode of alkaline storage batteries such as nickel-cadmium storage batteries and nickel-hydrogen storage batteries. It is what

That is, according to the present invention, in order to increase the conductivity of nickel hydroxide used in the nickel electrode for alkaline storage batteries, trivalent cobalt oxyhydroxide is added to nickel hydroxide as in the prior art. The charge / discharge capacity of the negative electrode of the storage battery does not decrease, and the nickel electrode does not contain impurities, and a nickel electrode for an alkaline storage battery is obtained that has excellent conductivity, high capacity, and excellent cycle characteristics. The task is to do so.

[0014]

In order to solve the above problems, the nickel electrode for an alkaline storage battery according to the present invention is mainly composed of particles mainly containing nickel hydroxide and cobalt-containing nickel oxyhydroxide. The active material in which divalent cobalt was added to the mixture of particles was used.

Here, as in the nickel electrode for an alkaline storage battery according to the present invention, divalent cobalt is added to a mixture of particles mainly containing nickel hydroxide and particles mainly containing cobalt-containing nickel oxyhydroxide. When the added active material is used and the nickel electrode is used as a positive electrode of an alkaline storage battery for charging, the added divalent cobalt is oxidized to trivalent cobalt by irreversible oxidation. In addition to nickel hydroxide, the active material contains nickel oxyhydroxide obtained by previously oxidizing nickel hydroxide, so it is not necessary to oxidize and charge the nickel oxyhydroxide during charging, while Nickel oxyhydroxide is reduced and becomes discharged. Therefore, in the nickel electrode for an alkaline storage battery according to the present invention, it is possible to prevent the depth of charge in the negative electrode from increasing due to the irreversible oxidation of divalent cobalt as in the conventional case, and it is possible to charge and discharge the negative electrode that can be used in the conventional manner. The capacity does not decrease and the cycle life of the alkaline storage battery does not decrease.

Further, in the nickel electrode for an alkaline storage battery according to the present invention, since the cobalt-containing nickel oxyhydroxide containing cobalt in the particles containing nickel oxyhydroxide as a main component as described above is used, As a result, the oxygen generation potential increases, oxygen generation during charging is suppressed, the charge potential also decreases, and the charge / discharge capacity of the nickel electrode increases.

Here, in the nickel electrode for an alkaline storage battery according to the present invention, when cobalt is contained in the particles mainly composed of nickel oxyhydroxide as described above,
When the content is small, it is not possible to sufficiently suppress the oxygen generation as described above or to increase the capacity by lowering the charging potential. Therefore, it is preferable to use cobalt for the particles mainly containing nickel oxyhydroxide. 1% by weight or more.

In addition, when divalent cobalt is added to the active material in the nickel electrode for alkaline storage batteries of the present invention, if the amount of divalent cobalt is small, this divalent cobalt is oxidized to highly conductive trivalent cobalt. However, if the amount of this divalent cobalt is too large, the amount of nickel hydroxide or nickel oxyhydroxide in the nickel electrode will be small, and the conductivity of the battery will not be improved. Since the capacity decreases, it is preferable to add divalent cobalt in the range of 3 to 25% by weight based on the total weight of the active material.

Regarding the ratio of the particles containing cobalt-containing nickel oxyhydroxide as the main component and the above-mentioned divalent cobalt, when the amount of nickel oxyhydroxide is small with respect to the divalent cobalt, the charging is performed as described above. At times, when divalent cobalt is oxidized to trivalent cobalt, it is not possible to sufficiently suppress the increase of the charging depth in the negative electrode, and the available charge / discharge capacity of the negative electrode is reduced to reduce the cycle of the alkaline storage battery. While the life is shortened, if the amount of this nickel oxyhydroxide becomes too large, charging and discharging will be performed at a shallow charge depth of the negative electrode, sufficient capacity cannot be obtained, and the negative electrode deteriorates. The cycle characteristics as a battery deteriorate. Therefore, it is preferable that the amount of the particles containing nickel oxyhydroxide as the main component is in the range of 50 to 200% by weight with respect to the divalent cobalt.

[0020]

EXAMPLES A nickel electrode for an alkaline storage battery according to an example of the present invention will be specifically described below, and a comparative example will be given. When the nickel electrode for an alkaline storage battery in this example is used, the charge / discharge capacity of the alkaline storage battery is improved. It is shown that the cost is high and the cycle characteristics are improved. In addition, the nickel electrode for alkaline storage battery in the present invention,
The present invention is not limited to those shown in the following examples, and various modifications can be made without departing from the scope of the invention.

Example 1 [Preparation of Positive Electrode Active Material] Nickel hydroxide particles containing 1.984% by weight of cobalt were dipped in a 5 times equivalent aqueous solution of potassium peroxodisulfate to prepare the nickel hydroxide. Was oxidized to nickel oxyhydroxide at 80 ° C., filtered, washed with water and dried to obtain cobalt oxyhydroxide containing cobalt, that is, the above cobalt-containing nickel oxyhydroxide. The content of cobalt in this cobalt-containing nickel oxyhydroxide was 2% by weight.

Next, to 100 g of water, cobalt sulfate CoSO 4 was added.
8.34 g of ₄ was dissolved, and nickel hydroxide particles 9
0 g and 5 g of cobalt-containing nickel oxyhydroxide obtained as described above were suspended, and 1 mol
/ L NaOH aqueous solution was added dropwise to this suspension to make it alkaline, thereby depositing divalent cobalt cobalt hydroxide on the surfaces of nickel hydroxide and cobalt-containing nickel oxyhydroxide, respectively.

The nickel hydroxide and cobalt-containing nickel oxyhydroxide having cobalt hydroxide deposited on the surface in this manner were filtered, washed with water and dried to obtain an active material used for the nickel electrode. The weight ratio of nickel hydroxide, cobalt-containing nickel oxyhydroxide, and cobalt hydroxide deposited on the surface of the active material was 90: 5: 5.

[Preparation of Positive Electrode] To prepare a positive electrode, 80 parts by weight of the above active material was added to 20 parts by weight of an aqueous solution containing 1% by weight of methylcellulose, and this was kneaded into a paste. A porous body made of nickel-plated foam metal (porosity 95%, average pore diameter 200 μm) was filled, dried and molded to prepare a non-sintered positive electrode made of a nickel electrode. The weight of the active material contained in each nickel electrode was 4 g.

[Manufacture of Negative Electrode] When manufacturing a negative electrode, a misch metal (Mm) -based hydrogen storage alloy is used, and a hydrogen storage alloy having a composition of MmNi _3.2 Co _1.0 Al _0.2 Mn _0.6 is used. 5% by weight of polyethylene oxide was added, and water was further added to adjust the viscosity thereof to obtain a paste having a year of 30,000 mPa · s. The viscosity was measured using a B-type viscometer (B8U type) manufactured by Tokyo Keiki Co., Ltd. at a rotation speed of 20 rpm by the spindle TB.

Next, the paste obtained as described above is placed in a container, a punching metal obtained by plating iron with nickel is placed in this container, and the above-mentioned paste is applied to a core body made of this punching metal. Was dried and molded to prepare a negative electrode composed of a hydrogen storage alloy electrode.

[Preparation of Battery] In preparing an alkaline storage battery, as shown in FIG. 1, a separator 3 made of a nylon nonwoven fabric is interposed between the positive electrode 1 and the negative electrode 2 prepared as described above. The spirally wound product is inserted into the battery can 4, and 30 wt% KOH is placed in the battery can 4.
After injecting 2.4 g of the alkaline electrolyte of, the battery can 4
And a positive electrode 1 is connected to a positive electrode external terminal 6 via a positive electrode lead 5, while a negative electrode 2 is connected to a battery can 4 via a negative electrode lead 7 to obtain a cylindrical sealed nickel-hydrogen storage battery. It was

Example 2 In this example, in the production of the positive electrode active material in Example 1, in obtaining cobalt-containing nickel oxyhydroxide, the inside of the electrolytic cell was partitioned into two parts by a porous plate, and The electrolytic cell was filled with a 6 mol / l KOH aqueous solution, and nickel hydroxide containing 1.984% by weight of cobalt was placed in one of the partitioned electrolytic cells and stirred to suspend it. 300mA
Current was applied for 5 hours to oxidize the above nickel hydroxide into nickel oxyhydroxide.

Then, other than that, the embodiment 1 is used.
An alkaline storage battery was produced in the same manner as in the above.

(Comparative Example 1) In this comparative example, cobalt-containing nickel oxyhydroxide was not used in [Preparation of positive electrode active material] in Example 1 and water 10 was added.
95 g of nickel hydroxide particles was added to an aqueous solution in which 8.34 g of CoSO ₄ was dissolved in 0 g.
An alkaline storage battery was produced in the same manner as in Example 1 above.

Comparative Examples 2 and 3 In Comparative Example 2, nickel hydroxide particles containing no cobalt were used to obtain nickel oxyhydroxide in [Preparation of positive electrode active material] in Example 1. Nickel oxyhydroxide was obtained, otherwise the above Example 1
An alkaline storage battery was produced in the same manner as in the above. Also,
In Comparative Example 3, the cobalt hydroxide-free nickel hydroxide particles were oxidized as shown in Example 2 above to obtain cobalt-free nickel oxyhydroxide, and otherwise, as described above. An alkaline storage battery was prepared in the same manner as in Example 1.

Next, for each of the alkaline storage batteries of Examples 1 and 2 and Comparative Examples 1 to 3 produced as described above,
Charged for 1.2 hours with a charging current of 1A and discharging current of 1A
Then, the battery was discharged until the final voltage reached 1 V, and charging / discharging was repeated under such charging / discharging conditions. The relationship between the number of cycles and the discharge capacity in each of these alkaline storage batteries was investigated, and the results are shown in FIG. .

Regarding the alkaline storage batteries of Examples 1 and 2 and Comparative Example 1 described above, after charging and discharging once, these alkaline storage batteries were disassembled and lead wires were attached to the respective positive and negative electrodes. 30 wt% K
Immersed in OH aqueous solution, Hg / HgO at discharge current 1A
The electrodes were discharged until the final voltage on the electrodes reached 0 V, and the remaining capacity at each electrode was measured. The results are shown in Table 1 below.

[0034]

[Table 1]

As a result, as shown in Table 1, in the alkaline storage battery of Comparative Example 1, the remaining capacity at the negative electrode was larger than that of the alkaline storage batteries of Examples 1 and 2, and the charging depth of the negative electrode was deep. .

This is because, in the alkaline storage battery of Comparative Example 1, cobalt hydroxide, which is divalent cobalt deposited on the surface of nickel hydroxide, was trivalent due to irreversible oxidation by the first cycle charging as described above. Since cobalt oxyhydroxide is used, it is considered that the remaining capacity in the negative electrode is larger than the initial capacity by the capacity used for this oxidation.

On the other hand, also in the case of the alkaline storage batteries of Examples 1 and 2, cobalt hydroxide, which is divalent cobalt deposited on the surface of nickel hydroxide, is irreversibly oxidized by trivalent oxy water when charged in the first cycle. Although it becomes cobalt oxide, in the alkaline storage batteries of Examples 1 and 2, since nickel oxyhydroxide was previously contained in the positive electrode before charging, it was necessary to oxidize and charge this nickel oxyhydroxide at the time of charging. When the battery is discharged, the nickel oxyhydroxide is reduced and discharged, so that the increase in the remaining capacity of the negative electrode is suppressed.

As described above, in the case of the alkaline storage battery of Comparative Example 1, as compared with the alkaline storage batteries of Examples 1 and 2, the remaining amount in the negative electrode was higher from the initial stage, and as a result, the capacity of the uncharged portion of the negative electrode was increased. When the hydrogen storage alloy used in the negative electrode gradually deteriorates due to repeated charging and discharging, the alkaline storage battery of Comparative Example 2 in which the capacity of the uncharged portion in the negative electrode is small is the first in the negative electrode. The uncharged portion is consumed, and as shown in FIG.
It is considered that the discharge capacity gradually decreased after 300 cycles of charging and discharging, and the cycle life thereof became shorter than that of the alkaline storage batteries of Examples 1 and 2.

When comparing the alkaline storage batteries of Examples 1 and 2 with the alkaline storage batteries of Comparative Examples 2 and 3, the alkaline storage batteries of Examples 1 and 2 have a larger discharge capacity and a slightly longer cycle life. Was there. This is Example 1,
In the alkaline storage battery of No. 2, since cobalt-containing nickel oxyhydroxide containing cobalt in its nickel electrode is used, the cobalt in the cobalt-containing nickel oxyhydroxide increases the oxygen generation potential during charging. It is considered that this is because the generation of oxygen was suppressed and the charge potential was lowered, which improved the acceptability of charge.

(Experimental Example 1) In this Experimental Example, in [Preparation of Positive Electrode Active Material] in Example 1, the amount of cobalt in the cobalt-containing nickel oxyhydroxide was changed as shown in Table 2 below. Otherwise, except that, an alkaline storage battery was manufactured in the same manner as in the case of Example 1 above, and each alkaline storage battery thus manufactured was charged / discharged under the same charge / discharge conditions as in the above case. The initial battery capacity was measured, and the results are also shown in Table 2.

[0041]

[Table 2]

As a result, when the amount of cobalt in the cobalt-containing nickel oxyhydroxide is 1% by weight or more,
It has been found that the battery capacity is large, which is preferable.

(Experimental Example 2) In this Experimental Example, in [Preparation of Positive Electrode Active Material] in Example 1, nickel hydroxide in the active material, cobalt-containing nickel oxyhydroxide, and divalent divalent metal added to them were added. The weight ratio with cobalt hydroxide, which is cobalt, was changed as shown in Table 3 below, and an alkaline storage battery was produced in the same manner as in Example 1 except for the above. The amount of cobalt in the cobalt-containing nickel oxyhydroxide was 2% by weight, which was the same as in Example 1 above.

Next, each alkaline storage battery thus manufactured was charged and discharged under the same charging and discharging conditions as in the above case, the initial battery capacity of each alkaline storage battery was measured, and the results are shown in Table 3 together. Indicated.

[0045]

[Table 3]

As a result, it was found that a high battery capacity was obtained in the alkaline storage battery in which the amount of divalent cobalt added to the active material was in the range of 3 to 25% by weight.
This is because if the amount of divalent cobalt added is less than 3% by weight, even if it is oxidized to trivalent cobalt oxyhydroxide, it will not be possible to give sufficient conductivity to the nickel electrode and the battery capacity will decrease. On the other hand, when the amount of divalent cobalt added is more than 25% by weight, the amount of nickel hydroxide and nickel oxyhydroxide that act as a reaction active material decreases, and the battery capacity decreases.

(Experimental Example 3) In this experimental example, the amount of nickel oxyhydroxide containing cobalt was changed in [Preparation of positive electrode active material] in Example 1 so that the hydroxide in the active material was changed. The weight ratio of nickel, cobalt-containing nickel oxyhydroxide, and cobalt hydroxide, which is divalent cobalt to be added thereto, is shown in Table 4 below.
The weight ratio (% by weight) of cobalt-containing nickel oxyhydroxide to cobalt hydroxide was changed as shown in the same table, and otherwise the same as in Example 1 above. A storage battery was produced. The amount of cobalt in the cobalt-containing nickel oxyhydroxide was 2% by weight, which was the same as in Example 1 above.

Next, each of the alkaline storage batteries thus produced was charged and discharged under the same charge and discharge conditions as in the above case, and the cycle life of charge and discharge was examined until the discharge capacity reached 800 mAh, and the results are shown in Table 4. It is also shown.

[0049]

[Table 4]

As a result, the ratio of cobalt-containing nickel oxyhydroxide to cobalt dihydric cobalt hydroxide was 5%.
In the alkaline storage battery in the range of 0 to 200% by weight, the charge / discharge cycle life was improved. This is because when the weight ratio of cobalt-containing nickel oxyhydroxide to cobalt hydroxide is less than 50% by weight, the negative electrode in the case where cobalt hydroxide of divalent cobalt becomes trivalent cobalt oxyhydroxide by irreversible oxidation. While the increase in the remaining capacity cannot be suppressed sufficiently and the amount of use of the negative electrode decreases, when the weight ratio of cobalt-containing nickel oxyhydroxide exceeds 200% by weight, charging / discharging is performed at a shallow charge depth of the negative electrode. This is because, as described above, a sufficient battery capacity cannot be obtained and the negative electrode is easily deteriorated.

In this embodiment, nickel hydroxide and nickel oxyhydroxide were separately prepared and mixed in preparation of the positive electrode active material. However, a part of nickel hydroxide was oxidized. It is also possible to mix nickel hydroxide and nickel oxyhydroxide.

In this embodiment, a nickel-hydrogen storage battery is used as the alkaline storage battery, but the same effect can be obtained with other alkaline storage batteries such as nickel-cadmium storage battery and nickel-zinc storage battery. .

[0053]

As described above in detail, in the nickel electrode for alkaline storage batteries according to the present invention, particles containing nickel hydroxide as a main component and particles containing cobalt-containing nickel oxyhydroxide as a main component are mixed. Since an active material to which divalent cobalt has been added is used, when the nickel electrode is used as a positive electrode of an alkaline storage battery for charging, divalent cobalt is oxidized into trivalent cobalt by irreversible oxidation. Even if the increase in the remaining capacity in the negative electrode is suppressed by the cobalt-containing nickel oxyhydroxide described above, the cobalt contained in the cobalt-containing nickel oxyhydroxide also improves the charge / discharge capacity in the nickel electrode, and improves the conductivity. A nickel electrode for an alkaline storage battery, which is excellent and has a large capacity and excellent cycle characteristics, was obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view showing an internal structure of an alkaline storage battery manufactured in Examples and Comparative Examples of the present invention.

FIG. 2 is a diagram showing the relationship between the discharge capacity and the number of cycles in each alkaline storage battery produced in Examples 1 and 2 and Comparative Examples 1 to 3.

[Explanation of symbols]

 1 Positive electrode (nickel electrode)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Mutsumi Yano 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Kozo Nogami 2-5-5 Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. (72) Inventor Ikuro Yonezu 2-5-5 Keihanhondori 2-chome, Moriguchi-shi, Osaka Prefecture (72) Inventor Koji Nishio 2 Keihanhondori, Moriguchi-shi, Osaka 5-5, Sanyo Electric Co., Ltd.

Claims (4)

[Claims] 1. An active material in which divalent cobalt is added to a mixture of particles containing nickel hydroxide as a main component and particles containing cobalt-containing nickel oxyhydroxide as a main component. Nickel electrode for alkaline storage batteries. 2. The nickel electrode for an alkaline storage battery according to claim 1, wherein 1% by weight or more of cobalt is contained in the particles containing cobalt-containing nickel oxyhydroxide as a main component. Nickel electrode for. 3. The nickel electrode for an alkaline storage battery according to claim 1 or 2, wherein the divalent cobalt is added in a range of 3 to 25% by weight based on the total weight of the active material. Nickel electrode for alkaline storage battery. 4. The nickel electrode for an alkaline storage battery according to claim 1, wherein the particles containing cobalt-containing nickel oxyhydroxide as a main component are 50 to 200 with respect to the divalent cobalt. A nickel electrode for an alkaline storage battery, characterized in that it is contained in the active material in a weight% range.