JPS61181074A - Manufacture of alkaline battery positive electrode - Google Patents

Abstract

PURPOSE:To improve the availability by functioning ammonia onto the nickel salt then functioning caustic alkali to produce nickel hydroxide to be employed as the active substance. CONSTITUTION:Ammonia is functioned onto nickel salt to convert into ammonia complex then caustic alkaline is functioned to precipitate nickel hydroxide which is collected to be employed as the active substance. The crystal particles of nickel hydroxide have countless projections on the surface to increase the surface area. Said crystal is spherical and not gelatinized but easily filtered and will be the nucleus for producing second stage hydroxide through caustic alkaline solution. Ammonia is added by 0.4-6mol to 1mol of nickel salt. Conse quently, high availability is achieved to facilitate removal of liquid through filtering resulting in shortening of manufacturing time.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for producing a nickel oxide anode for an alkaline storage battery, and more particularly to a method for producing a nickel hydroxide anode active material.

(b) Conventional technology Nickel oxide anodes (hereinafter referred to as anodes) used in alkaline storage batteries that use nickel oxide such as nickel hydroxide as an active material have mainly been of the sintered type. This is because it has excellent high rate discharge performance, cycle life, and active material utilization rate, but on the other hand, it has problems such as high cost and long manufacturing time. In recent years, active material powder has been mixed with a conductive material, a binder, and water, and anodes have been developed by coating and drying a paste on a current collector plate, and anodes are anodes made by filling a sponge-like or felt-like porous metal body with powdered active materials. There is increasing interest in non-sintered anodes that are fabricated using raw material powders.

Particularly in non-sintered anodes, the quality of the properties of the active material, nickel hydroxide, is a major factor in determining the performance of the electrode plate, but the basic manufacturing method for this active material is A precipitate obtained by reacting an aqueous salt solution with an aqueous caustic alkali solution such as sodium hydroxide or potassium hydroxide (neutralization method); this solution is dried.

After going through the steps of coarse pulverization, water washing, drying, and pulverization, it becomes a completed active material (Alkaline 8trage Batt
eries.

Folks). This active material manufacturing method requires a long time to filter and remove liquid because the precipitate obtained by reacting nickel salt and caustic alkali is gel-like, and if washed with water immediately after filtering, it becomes gel-like again, so it is first dried. It is also necessary to perform coarse grinding to form particles. In addition, the above-mentioned active materials have a drawback that the utilization rate is not sufficiently high.

In contrast, Japanese Patent Application Laid-Open No. 53-44844.

JP-A-56-134471 and JP-A-57-51
) A new manufacturing method is proposed in Publication No. 31, but 1% Publication No. 55-44844 uses a nickel salt, an oxidizing agent, and a caustic alkali to form Nip as an active material. This method has the same problems as the method for producing nickel hydroxide described above. Also, JP-A-56-134471
No. 57-51) and JP-A-57-51) 31 both have the problem that the utilization rate of the finished active material cannot be improved.

(c) Problems to be Solved by the Invention The present invention aims to provide a method for producing nickel hydroxide that shortens the time required for production and has a high utilization rate as an electrode active material.

) measures to resolve the problem; A method for manufacturing an anode for an alkaline storage battery according to the present invention.

After the nickel salt is made to react with ammonia to form an ammonia complex, nickel hydroxide is precipitated by the action of caustic alkali, and the precipitate is collected and used as an active material.

(e) Effect The inventor investigated various conditions for producing nickel hydroxide by the neutralization method, and among them: 1) Adding ammonia to a nickel salt aqueous solution as a first step to form nickel into an ammonia complex;
Then (2) in the second step, this is treated with caustic alkali to produce fc nickel hydroxide, which can be easily filtered in the subsequent process.

It has also been found that it has a high utilization rate as an active material. The process of producing nickel hydroxide described above is represented by the following reaction formula. When nickel salt and caustic alkali are nickel nitrate and sodium hydroxide, respectively) ■N1 (No z + 4NH5 + 2H20 → (NiCNH
s)4CH20)2]CN05)2■(Ni(NH5)
a(HB))2](NOx)z+2NaOH-Ni(O
H) 2+2NaNOx+2H20+4NHs Figure 1 shows an electron micrograph (X5QOO) of nickel hydroxide as the active material in the present invention obtained by aging, filtering, washing with water, drying, and pulverizing the nickel hydroxide produced by the above method.
In addition, the nickel salt aqueous solution is directly treated with a caustic alkaline aqueous solution to age it, then filtered, dried, pulverized, washed with water, dried,
Electron micrograph of conventional nickel hydroxide obtained by crushing (
X 5000) is shown in FIG. It can be seen that the crystal particles of nickel hydroxide in the present invention have numerous pleat-like protrusions on the surface and have a larger surface area than the conventional ones.

It is thought that this large surface area is the reason for the high utilization rate, but the reason why such large surface area crystals are obtained is not clear. However, the following is inferred.

In the production method using the neutralization method of nickel hydroxide, the factors that affect the physical properties of the product are considered to be temperature, presence or absence of aging, alkali concentration, production rate, etc., but conventional nickel salts are used to directly act on caustic alkali. In the production method, the reaction was so rapid that even attempts to slow the production rate could not be substantially controlled. However, in the present invention, the alkali salt is converted into an ammonia complex ((Ni(NH
s)4(Hzo)z] ) and then converted to hydroxide (Ni(OH)z) with caustic alkali, and the reaction rate at which this ammonia complex is converted to hydroxide is faster than that of the conventional method. As shown in Figure 1, crystal growth is more likely to occur. In addition, when ammonia is applied to a nickel salt solution to remove the solution, it becomes alkaline and a small amount of nickel hydroxide is produced, but the crystals are spherical and do not form a gel-like substance at all, and are extremely easy to form in the furnace. This crystal becomes the core of the second stage of hydroxide production using a caustic alkaline solution.

Next, the amount of ammonia added was varied from 0.4 to 6 moles per mole of nickel salt, and nickel hydroxide was produced by the method of the present invention to confirm its effect. The relationship between the amount added and the utilization rate of the produced nickel hydroxide is shown in FIG. As is clear from FIG. 3, the effect of ammonia becomes significant when the amount of ammonia added is 2 mol or more per 41 mol of nickel.

(f) Example [Example 1] Nickel nitrate 17 l/l aqueous solution 1)! To this, aqueous ammonia containing 4 moles of ammonia was added, and this solution (containing a small amount of nickel hydroxide precipitate) was then stirred into a 47 l/e aqueous solution of sodium hydroxide (1)! After aging for 1 hour while continuing to stir, the mixture is filtered, washed with water, and dried. After drying, it is crushed and passed through 200 meshes to obtain a finished active material.

Incidentally, all of the above operations up to the internal aqueous step were performed at room temperature.

92 parts of nickel hydroxide and 8 parts of cobalt hydroxide thus obtained
A paste containing a paste and hydroxypropylcellulose is mixed to form a paste, which is filled into a sponge-like porous nickel material, dried, and compressed under pressure to form an anode.

[Example 2] In Example 1, ammonia gas was used instead of ammonia water, and bubbling was carried out so that 4 moles of the ammonia gas was dissolved in the nickel nitrate solution.

Otherwise, the anode was obtained by the same operation.

[Comparative example]

Nitrogen M nickel 1 mol/e solution 1)! A stirring solution of 47 l/l of sodium hydroxide 1)! In addition, the mixture is aged for 1 hour while stirring, then dried in a furnace, dried, coarsely crushed, washed with water, dried, crushed, and passed through a 200-mesh mesh to obtain a finished active material.

Using the nickel hydroxide thus obtained, an anode was obtained in the same manner as in Example 1.

A nickel-cadmium battery combining the anode obtained in the above examples and comparative examples with a sintered cadmium cathode
- constructed and measured the active material utilization rate.

The results are shown in the table below. At the same time, the time required for producing the active material is shown as Comparative Example t-100.

The manufacturing time required for the example was shorter than that of the comparative example in the table.
This is because the reduction to 55 parts and the subsequent drying and coarse grinding steps in an alkali-containing state could be omitted.

(l) Effects of the invention A method for manufacturing an anode for an alkaline storage battery according to the present invention.

The nickel salt is reacted with ammonia to form an ammonia complex, the nickel salt is then reacted with caustic alkali to form nickel hydroxide, and the nickel hydroxide is used as an active material. Since nickel oxide has a large surface area, a high utilization rate can be obtained. Further, the nickel hydroxide produced by the interaction with the caustic alkali can be easily removed by filtration, and the time required for production can be shortened, so it has great industrial value.

[Brief explanation of drawings]

Figure 1 is a photograph showing the particle structure of nickel hydroxide produced by the method of the present invention, Figure 2 is a photograph showing the particle structure of nickel hydroxide produced by the conventional method, and Figure 3 is a photograph showing the particle structure of nickel hydroxide produced by the conventional method. It is a drawing showing the relationship between the amount and the utilization rate of the generated active material.

Claims (4)

[Claims] (1) An alkaline storage battery characterized in that nickel salt is reacted with ammonia to form an ammonia complex, and then nickel hydroxide is produced by reacting with caustic alkali, and the nickel hydroxide is used as an active material. Manufacturing method of anode for use. (2) The method for producing an anode for an alkaline storage battery according to claim (1), wherein the amount of ammonia acting to form the ammonia complex is 2 mol or more per 1 mol of the nickel salt. (3) The method for producing an anode for an alkaline storage battery according to claim (1), wherein the ammonia complex is formed by adding aqueous ammonia to a nickel salt solution. (4) The method for producing an anode for an alkaline storage battery according to claim (1), wherein the ammonia complex is formed by bubbling ammonia gas into a nickel salt solution.