JP2001307734A - Powder of raw material for production of positive electrode of alkaline secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide powder of raw material for manufacturing a positive electrode of an alkaline secondary battery. SOLUTION: This raw material powder is constituted by mixed and compacted granular powder 3 of nickel hydroxide powder 1 and continuity assistant powder 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a raw material powder for producing a positive electrode of an alkaline secondary battery.

[0002]

2. Description of the Related Art In general, nickel cadmium batteries and nickel hydrogen batteries are known as alkaline secondary batteries.
This alkaline secondary battery includes a spiral battery and a button battery. The spiral battery is a battery having a structure in which a plate-shaped positive electrode and a negative electrode are spirally wound via a separator, and charged in a cylindrical container. The button battery is a battery having a structure in which a positive electrode and a negative electrode are each compacted and inserted into a coin-shaped container via a separator.

[0003] There are a sintered substrate method and a paste method as a method for producing a positive electrode of a spiral battery. The sintered substrate method involves a hydrolysis reaction in a void of a porous nickel sintered substrate obtained by baking metallic nickel powder on a perforated metal plate. To produce a positive electrode by depositing nickel hydroxide. On the other hand, in the paste method, a nickel hydroxide powder is mixed with a powder of an electric conduction aid such as cobalt oxide and an organic binder to form a paste, and the paste is filled in the voids of the nickel foam plate and pressed to produce a positive electrode. Is the way.

[0004] The foamed nickel plate is manufactured by applying carbon to urethane foam, electroplating Ni, and firing. By press-consolidating the paste, the paste is filled into the pores opened on the surface of the foamed nickel plate and continuous with the internal pores to form the positive electrode.

The positive electrode manufactured by the sintered substrate method has a lower material cost than the positive electrode manufactured by the paste method.
Since the amount of nickel hydroxide that can be precipitated in a single hydrolysis treatment inside the sintered substrate is small and usually requires five to six hydrolysis treatments, it takes time and effort to manufacture the positive electrode, and the processing cost is high. . On the other hand, the positive electrode manufactured by the paste method has a lower processing cost than the positive electrode manufactured by the sintered substrate method, but the foamed nickel plate is manufactured through a complicated process as described above, so that the cost is high, and therefore the conventional nickel plate is expensive. In the paste method, since the material cost is high, it was difficult to reduce the price of the positive electrode of the alkaline secondary battery obtained by this method.

Therefore, in recent years, an eye-shaped composite powder 33 as shown in the sectional view of FIG. 2 in which the surface of nickel hydroxide powder is reduced with hydrazine and a reduced nickel layer 2 is formed on the surface of nickel hydroxide 1 has been produced. It has been developed, and it is going to manufacture the positive electrode of an alkaline secondary battery using this eyeball-shaped composite powder. This eye-shaped composite powder 33 does not need to mix the nickel hydroxide powder and the nickel powder as in the related art, since the surface of the nickel hydroxide 11 is coated with the reduced nickel layer 22 as a current-carrying agent. Since the positive electrode can be manufactured only by forming the eye-shaped composite powder 33 into a paste together with an organic binder and applying it to a perforated metal plate and drying it, the manufacturing process can be simplified and the cost can be greatly reduced.

[0007]

However, the above-mentioned eye-shaped composite powder still requires a long time to make the nickel layer formed by reducing the surface of the nickel hydroxide powder with hydrazine, thereby reducing the material cost. Is difficult, and the positive electrode of an alkaline secondary battery manufactured using this eye-shaped composite powder as a raw material powder is covered with a low-conductive organic binder around all the eye-shaped composite powders to isolate each eye-shaped composite powder. Therefore, there has been a problem that the conductivity of the resulting positive electrode is reduced, and the obtained positive electrode is not easily energized, and the characteristics of the positive electrode are significantly reduced.

[0008]

Means for Solving the Problems Accordingly, the present inventors have:
As a result of conducting research to more easily produce a high-performance positive electrode for alkaline secondary batteries at a low cost, a compact was prepared by compacting a mixed powder of nickel hydroxide powder and a current-carrying agent powder. Is crushed and sieved into granules, whereby a mixed powder of the nickel hydroxide powder 1 and the current-carrying agent powder 2 as shown in FIG. The obtained mixed compacted granular powder 3 was prepared, the mixed compacted granular powder 3 was made into a paste together with an organic binder, applied to a perforated metal plate (not shown), and dried to manufacture. The positive electrode of the alkaline secondary battery is bonded between the mixed compacted granular powders with an organic binder,
Since the inside of the mixed compacted granular powder is press-welded with the nickel hydroxide powder and the current-carrying auxiliary powder, the current is not interrupted, and the majority is occupied by the mixed compacted granular powder having a relatively large particle size. Therefore, the use of an organic binder can be reduced, so that the decrease in the electrical conductivity is small, and thus the positive electrode characteristics are greatly improved.In addition, the production process is carried out because the production process of the mixed compacted granular powder is dry. They found that it was easy.

The present invention has been made based on this finding, and (1) a raw material powder for producing a positive electrode of an alkaline secondary battery, comprising a mixed compacted granular powder of a nickel hydroxide powder and a current-carrying aid powder. , Are characterized by:

[0010] Nickel powder,
Any one or more of the cobalt powder and the cobalt oxide powder can be used. Therefore, the present invention relates to (2) an alkali secondary powder comprising a mixed compacted granular powder of nickel hydroxide powder and nickel powder. Raw material powder for battery positive electrode production; (3) Mixed compaction of nickel hydroxide powder and cobalt powder; Raw material powder for alkaline secondary battery positive electrode production consisting of granular powder; (4) Mixed compaction of nickel hydroxide powder and cobalt oxide powder Raw material powder for producing a positive electrode for an alkaline secondary battery comprising a granular body powder, (5) a nickel hydroxide powder, and an alkali comprising a mixed compacted granular powder of two or more of nickel powder, cobalt powder and cobalt oxide powder Raw material powder for producing a positive electrode for a secondary battery.

[0011] The amount of the current-carrying aid powder contained in the raw material powder for producing a positive electrode of an alkaline secondary battery comprising the mixed compacted granular powder of the present invention varies depending on the type of the current-carrying agent. In this case, the content is preferably 15 to 40% by mass. When the current-carrying agent powder is cobalt or cobalt oxide, the content is preferably in the range of 5 to 15% by mass.

[0012] Since the mixed and compacted granular powder 3 of the nickel hydroxide powder and the current-carrying aid powder is press-bonded by consolidation of the nickel hydroxide powder and the current-carrying aid powder, strong bonding is achieved. When the strength of the mixed compacted granular powder 3 is particularly required, the mixed compacted granular powder 3
For example, it is preferable to impregnate a PTFE-based organic binder (not shown). Even when impregnated with an organic binder, the nickel hydroxide powder 1 and the current-carrying aid powder 2 are still in pressure contact with each other, so that the current-carrying characteristics are not significantly impaired. Therefore, the present invention provides (6) the above (1) to
(5) A raw material powder for producing a positive electrode for an alkaline secondary battery obtained by impregnating an organic binder into the mixed compacted granular powder described in (5).

Further, as shown in FIG. 1B, a known electroless plating method is applied to the surface of the mixed and compacted granular powder 3 described in the above (1) to (5). When the porous metal layer 4 such as a porous nickel layer or a porous cobalt layer is formed by coating, the porous metal layer 4 such as the porous nickel layer and the porous cobalt layer is a layer having excellent electrical conductivity. It is preferable because an energization network is formed in the positive electrode of the alkaline secondary battery to further improve the conductivity of the positive electrode. Therefore, the present invention provides (7) the above (1) to
(6) A raw material powder for producing a positive electrode for an alkaline secondary battery, comprising a coated mixed compacted granular powder obtained by coating a porous metal layer on the mixed compacted granular powder described in (6).

Although not shown, the above (6)
A porous metal layer may be formed on the surface of the mixed compacted granular powder impregnated with the organic binder described above. Therefore, the present invention relates to (8) a method of forming a mixture of the mixed and compacted granular powder obtained by further forming a porous metal layer on the surface of the mixed and compacted granular powder impregnated with the organic binder according to the above (6). Raw material powder for producing a positive electrode for an alkaline secondary battery,
It is characterized by the following.

Further, the porous metal layer is preferably a porous nickel layer and a porous cobalt layer. The particle diameter of the mixed compacted granular powder according to (1) to (5) or the coated mixed compacted granular powder according to (6) to (7) thus obtained is: All have an average particle size of 10
It is preferable that it is in the range of 0 to 400 μm.

In order to produce a positive electrode for an alkaline secondary battery using the raw material powder comprising the mixed compacted granular powder or the coated mixed compacted granular powder of the present invention, the above-mentioned (1) to (6)
Or the mixed compacted granular powder according to the above or (7) to
An organic binder is added to a raw material powder for producing a positive electrode of an alkaline secondary battery comprising the coated mixed compacted granular powder described in (8), and the mixture is kneaded to prepare a paste. The paste is applied to a perforated metal plate, After the application, a light press having a rolling reduction of about 3 to 30% is performed, followed by drying.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Example 1 Ni (OH) ₂ powder having an average particle size of 20 μm, average particle size:
A 2 μm CoO powder, a Co powder having an average particle diameter of 2 μm, and a Ni powder having an average particle diameter of 2 μm were prepared, and these powders were mixed and mixed so as to have a compounding composition shown in Table 1 to prepare a mixed powder. The mixed powder is roll-pressed into a compact, and the compact is crushed by a gear mill and sieved to obtain a granular alkaline secondary battery of the present invention having an average particle size shown in Table 1. Raw material powders (hereinafter, referred to as the granular powder of the present invention) 1 to 9 for producing a positive electrode were produced. To the thus obtained granular powders 1 to 9 of the present invention, a 5% by mass Teflon dispersion solution and a 1% by mass aqueous solution of carboxymethylcellulose were added to prepare a paste, and the paste was nickel-plated. Thickness: 60 μm Was coated on both sides of a perforated steel sheet to a thickness of 250 μm, dried, and roll-pressed to produce a positive electrode having a thickness of 410 μm excluding the thickness of the perforated steel sheet. On the other hand, a known Mm (Ni, Co, Mn, Al) ₅ -based hydrogen storage alloy powder is similarly applied to both sides of a perforated steel sheet so as to have a thickness of 250 μm, dried, and roll-pressed. A negative electrode having a thickness of 410 μm excluding the thickness of the perforated steel plate was manufactured.

An AA size sealed spiral battery was assembled by combining the positive electrode and the negative electrode, and a battery capacity test, a charge / discharge test, and a cycle life characteristic test were performed. The results obtained are shown in Table 1. The battery capacity test was performed at a temperature of 25.
After charging for 6 hours with a current of 200 mA
Evaluated by the battery capacity when discharged in A, the charge and discharge test
Temperature: 25 ° C., after charging at 200 mA, battery capacity: 2
The capacity at the time of discharging at a current corresponding to C was evaluated by the ratio to the battery capacity obtained by the battery capacity test. In the cycle life characteristic test, the battery was charged at 200 mA for 6 hours at a temperature of 25 ° C. and then discharged at 1000 mA. The time required for the battery voltage in the first cycle to reach 0.7 V was set to 100. When the discharge time was reduced to 70% or less of the first cycle, the life was evaluated by the number of cycles.

Conventional Example 1 The surface of nickel hydroxide powder was reduced with hydrazine,
A conventional eyeball-shaped composite powder having a nickel layer formed on the surface of nickel hydroxide powder was added with a 5% by mass Teflon dispersion solution and a 1% by mass aqueous solution of carboxymethylcellulose to prepare a paste, and this paste was plated with nickel. Thickness: applied to both sides of a perforated steel plate of 60 μm to a thickness of 250 μm and dried,
A positive electrode having a thickness of 410 μm excluding the thickness of the perforated steel plate was manufactured by roll pressing.

The obtained positive electrode was combined with the negative electrode prepared in Example 1 to assemble an AA-size sealed spiral battery, and a battery capacity test, a charge / discharge test and a cycle life characteristic test were performed in the same manner as in Example 1. Table 1 shows the obtained results.

[0021]

[Table 1]

From the results shown in Table 1, the sealed spiral battery incorporating the positive electrode manufactured using the granular powders 1 to 9 of the present invention is different from the sealed spiral battery incorporating the positive electrode manufactured using the conventional centerpiece composite powder. It can be seen that the characteristics are superior.

Example 2 The granular powders 1 to 9 of the present invention prepared in Example 1 were immersed in a 10% by mass Teflon (registered trademark) dispersion liquid for 20 minutes, then separated into a solid and a liquid, and dried to obtain Teflon dispersion. Granular powders 10 to 18 of the present invention impregnated with a version were prepared. Using these granular powders 10 to 18 of the present invention, a paste was prepared by adding a 5% by mass Teflon dispersion solution and a 1% by mass aqueous solution of carboxymethyl cellulose in the same manner as in Example 1, and the paste was nickel-plated. Thickness: Coated on both sides of a perforated steel plate of 60 μm to a thickness of 250 μm, dried, and roll pressed to produce a positive electrode with a thickness of 410 μm excluding the thickness of the perforated steel plate. did.

The obtained positive electrode was assembled with the negative electrode prepared in Example 1 to assemble a sealed AA-sized spiral battery, and a battery capacity test, a charge / discharge test and a cycle life characteristic test were performed in the same manner as in Example 1. Table 2 shows the obtained results.

[0025]

[Table 2]

From the results shown in Table 2, the sealed spiral battery incorporating the positive electrode prepared using the granular powders 10 to 18 of the present invention shows that the sealed spiral battery incorporating the positive electrode prepared from the conventional centerpiece composite powder shown in Table 1 was used. It can be seen that the characteristics are superior to the spiral battery.

Example 3 A porous nickel layer and a porous cobalt layer were formed on the surfaces of the granular powders 1 to 9 of the present invention by electroless plating the granular powders 1 to 9 of the present invention prepared in Example 1. The granular powder of the present invention comprising a coated mixed compacted granular powder 19-
27 were produced. Using these granular powders 19 to 27 of the present invention, a paste was prepared by adding a 5% by mass Teflon dispersion solution and a 1% by mass aqueous solution of carboxymethyl cellulose in the same manner as in Example 1, and this paste was nickel-plated. Thickness: Coated on both sides of a perforated steel plate of 60 μm to a thickness of 250 μm, dried, and roll pressed to produce a positive electrode with a thickness of 410 μm excluding the thickness of the perforated steel plate. did.

The obtained positive electrode was combined with the negative electrode prepared in Example 1 to assemble an AA size sealed spiral battery, and a battery capacity test, a charge / discharge test and a cycle life characteristic test were performed in the same manner as in Example 1. Table 3 shows the obtained results.

[0029]

[Table 3]

From the results shown in Table 3, the sealed spiral battery incorporating the positive electrode produced using the granular powders 19 to 27 of the present invention incorporates the positive electrode produced using the conventional eyeball-shaped composite powder shown in Table 1. It can be seen that the characteristics are superior to that of the sealed spiral battery.

Example 4 A porous nickel layer and a porous cobalt layer are formed on the surfaces of the granular powders 10 to 18 of the present invention prepared in Example 2 by electroless plating, and the coated and compacted granular powders are formed. Granular powders 28 to 36 of the present invention were produced. 5% by mass of Teflon dispersion liquid and 1% by mass of these granular powders 28 to 36 of the present invention in the same manner as in Example 1.
A paste was prepared by adding an aqueous solution of carboxymethylcellulose, and this paste was nickel-plated.
It is applied to a thickness of 50 μm, dried, and then roll-pressed to a thickness of 4 excluding the thickness of the perforated steel sheet.
A 10 μm positive electrode was manufactured.

The obtained positive electrode was combined with the negative electrode produced in Example 1 to assemble an AA size sealed spiral battery, and a battery capacity test, a charge / discharge test and a cycle life characteristic test were carried out in the same manner as in Example 1. Table 4 shows the obtained results.

[0033]

[Table 4]

From the results shown in Table 4, the sealed spiral battery incorporating the positive electrode prepared using the granular powders 28 to 36 of the present invention incorporates the positive electrode prepared using the conventional eyeball-shaped composite powder shown in Table 1. It can be seen that the characteristics are superior to that of the sealed spiral battery.

[0035]

According to the present invention, an alkaline secondary battery incorporating a positive electrode produced using a raw material powder for producing a positive electrode of an alkaline secondary battery comprising a mixed compacted granular powder according to the present invention is provided by a conventional nickel hydroxide powder having a surface coated with nickel. Compared with an alkaline secondary battery incorporating a positive electrode manufactured using a composite powder having a layer formed thereon, the secondary battery characteristics can be improved and a higher performance alkaline secondary battery can be provided. It can greatly contribute to development.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view of a raw material powder for producing a positive electrode of an alkaline secondary battery according to the present invention.

FIG. 2 is an explanatory sectional view of a conventional raw material powder for producing a positive electrode of an alkaline secondary battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nickel hydroxide powder 2 Electricity aid powder 3 Mixed compacted granular powder 4 Porous metal layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazusuke Sato 1-297 Kitabukuro-cho, Omiya-shi, Saitama F-term in Mitsubishi Materials Real Research Institute (reference) 5H050 AA07 AA08 AA19 BA11 BA14 CA02 CB17 DA10 DA11 EA02 EA03 EA12 EA23 FA09 FA17 FA18 GA03 GA10 GA22

Claims (7)

[Claims] 1. A raw material powder for producing a positive electrode of an alkaline secondary battery, comprising a mixed compacted granular powder of a nickel hydroxide powder and a current-carrying agent powder. 2. A compacted powder of a mixture of nickel hydroxide powder and a current-carrying aid powder of one or more of cobalt oxide powder, nickel powder and cobalt powder. Raw material powder for manufacturing cathode of alkaline secondary battery. 3. A raw material powder for producing a positive electrode for an alkaline secondary battery, wherein the mixed and compacted granular powder according to claim 1 or 2 is impregnated with an organic binder. 4. A positive electrode for an alkaline secondary battery, comprising a coated mixed compacted granular powder in which a porous metal layer is further formed on the surface of the mixed compacted granular powder according to claim 1 or 2. Raw material powder for production. 5. An alkali metal powder comprising a mixed and compacted granular powder in which a porous metal layer is further coated on the surface of the mixed and compacted granular powder impregnated with the organic binder according to claim 3. Raw material powder for secondary battery positive electrode production. 6. The method according to claim 4, wherein said porous metal layer is a porous nickel layer or a porous cobalt layer.
Or a raw material powder for producing a positive electrode for an alkaline secondary battery according to 5; 7. A positive electrode for an alkaline secondary battery produced from the raw material powder for producing a positive electrode for an alkaline secondary battery according to claim 1.