JPH0773860A - Manufacture of square alkaline battery - Google Patents

Abstract

PURPOSE:To manufacture at a low cost a square alkaline battery with high performance such as high rate discharge performance, high corrosion resistant battery case, and high reliability. CONSTITUTION:A battery case 1 is manufactured in the form of square pillar in which the vicinity of the opening is enlarged with a nickel plated steel plate, then by nickel plating again. A power generating element is put into the battery case 1, and a sealing member 7 is inserted into the opening of the battery case 1, then the opening is crimped to seal a battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a prismatic alkaline battery.

[0002]

2. Description of the Related Art In recent years, various types of prismatic alkaline batteries have been studied as batteries for small portable electric devices because they can have a high capacity and are excellent in space efficiency. The prismatic alkaline battery is manufactured as follows, for example. First, an electrode group in which strip-shaped positive electrode plates and negative electrode plates are alternately stacked via a separator is inserted into a battery case with a bottomed rectangular tube made of a nickel-plated steel plate, and an alkaline electrolyte is further added. Inject. Subsequently, a sealing body (sealing plate equipped with a safety valve or the like) is laser-welded or caulked and fixed to the opening of the battery case to hermetically seal the prismatic alkaline battery.

Since the battery case described above is formed by drawing, the steel plate is exposed by the peeling of the nickel plating during processing and rust occurs. Therefore, the steel plate with nickel plating on both sides in advance is drawn. After that, the inner and outer surfaces of the battery case may be nickel-plated again.
It is proposed by Japanese Patent No. 25666. Also, using a steel plate with nickel plating on only one side, after drawing so that the nickel plated surface is the inner surface of the battery case,
It is also possible to perform nickel plating on the inner and outer surfaces.
It is proposed by Japanese Patent No. 9393.

In the method of manufacturing the prismatic alkaline battery using the battery case described above, since the method of laser welding and sealing is adopted, the precise position between the opening having the same inner dimension as the body of the battery case and the sealing body is adopted. Since the matching is required, the processing and manufacturing cost increases. Therefore, from the viewpoint of reducing the manufacturing cost, it is desirable to adopt a method of sealing and fixing by crimping. However, the method of sealing and fixing by crimping is hardly adopted for the reason described below.

That is, when a steel plate is formed into a predetermined bottomed rectangular tube shape by deep drawing or the like and then nickel plated, the battery case is manufactured. Harder to be plated than. If the plating thickness on the inner surface of the battery case is insufficient, the resistance between the battery case and the electrode connected to the inner surface of the battery case increases, and the battery characteristics such as large current discharge characteristics deteriorate. For this reason, if the plating treatment time is lengthened in order to form the nickel plating film of sufficient thickness on the inner surface of the case, the plating thickness near the opening becomes too thick. When the vicinity of the battery case opening having such a plating thickness is bent inward and fixed by caulking, the nickel plating is peeled off because the vicinity of the opening is largely deformed. As a result, the steel is exposed from this peeling point and rust occurs, and this rust extends over the insulating gasket that insulates the battery case and the electrode terminal of the sealing body and causes a short circuit, or the sealing performance is impaired. There was a problem such as being lost.

On the other hand, a nickel-plated steel plate is deep-drawn into a square cylinder with a bottom, and further complicated forming such as expanding the opening to enable crimping is performed. When a battery case is manufactured, nickel plating is partially peeled off near the opening of the case when the above-mentioned complicated forming process is performed. As a result, there is a problem that the steel is exposed from the peeled portion and rust occurs.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the problems of the prior art, and has excellent battery characteristics such as large current discharge characteristics and high reliability in which rusting of the battery case is prevented. Another object of the present invention is to provide a method capable of manufacturing the prismatic alkaline battery at low cost.

[0008]

According to the present invention, a nickel-plated steel sheet is formed into a bottomed rectangular tube having an opening near the opening, and further nickel-plated to produce a battery case. A method for manufacturing a prismatic alkaline battery, comprising: a step of accommodating a power generation element in the battery case, and a step of caulking a sealing member to an opening of the battery case to close the sealing port. .

It is desirable that the thickness of the Ni plating film of the steel plate which has been subjected to the nickel plating treatment in advance is 1 to 8 μm. The reason is that if the thickness is less than 1 μm, the battery characteristics such as large current discharge characteristics may be deteriorated. On the other hand, if the thickness exceeds 8 μm, plating may be peeled off at the opening of the battery case at the time of sealing and rust may be generated.

The thickness of the Ni plating film formed when nickel plating is performed after the molding is preferably such that the maximum thickness formed near the opening of the battery case is 10 μm or less. The reason is that the thickness is 10
If the thickness exceeds μm, plating may be peeled off at the opening of the battery case at the time of sealing to cause rust.

The power generating element comprises, for example, an electrode group and an alkaline electrolyte. Examples of the electrode group include those in which strip-shaped positive electrode plates and negative electrode plates are alternately stacked with a separator interposed therebetween.

[0012]

According to the manufacturing method of the present invention, in forming a rectangular cylinder with a bottom, by using a steel plate that has been nickel-plated in advance, the plating thickness on the inner surface of the battery case is the same as other parts. Can be sufficient. Furthermore, by performing a nickel plating treatment after the molding process, it is possible to restore the plating peeling portion of the battery case that has occurred during the molding. Moreover, since the nickel plating time after the molding process can be shortened, it is possible to prevent the plating thickness near the opening of the battery case from becoming too thick.

After accommodating the power generating element in such a battery case, the sealing body is fixed to the opening of the battery case by caulking, and the sealing is made. It is possible to manufacture a prismatic alkaline battery in which the resistance between the electrode connected to the inner surface of the battery case and the battery characteristics such as large current discharge characteristics is improved. Also, since the plating thickness near the opening of the battery case does not become too thick, peeling of the plating does not occur even if caulking is fixed, and as a result, rust is prevented.
An improvement in reliability can be achieved. Moreover, since the method of fixing by caulking and sealing is adopted, the sealing can be performed more easily and the manufacturing cost can be reduced compared to the method of sealing by laser welding.

[0014]

Embodiments of the present invention will now be described in detail with reference to the drawings. Example 1 First, a flat steel plate having a nickel plating layer of 4 μm thick formed on both surfaces of a steel plate base material having a thickness of 0.4 mm was formed into a square cylinder with a bottom by deep drawing, and then the vicinity of the opening was further closed. The mouth is expanded to form a predetermined bottomed rectangular tube. Subsequently, nickel plating is performed on the entire bottomed rectangular steel plate so that the plating thickness formed in the vicinity of the opening is 1 μm at the maximum, that is, the total plating thickness in the vicinity of the opening is 5 μm at the maximum. Treated. Thereby, the battery case 1 as shown in FIG. 1 was produced.

Next, the electrode group is inserted into the battery case 1, and an alkaline electrolyte is further injected. Subsequently, a sealing body was fixed to the opening of the battery case 1 by caulking, and the sealing mouth was sealed to assemble a prismatic nickel-cadmium storage battery as shown in FIG. 2 described below.

That is, the electrode group 2 is housed in the battery case 1. The electrode group 2 is wrapped with three negative electrode plates 3 and a bag-shaped separator 4 impregnated with an alkaline electrolyte 2
The positive electrode plates 5 are vertically stacked alternately, and the negative electrode plates 3 are arranged on both sides and stacked so as to be in pressure contact with the inner surface of the battery case 1. Each of the negative electrode plates 3 is formed by filling an active material paste mainly containing cadmium hydroxide in a porous conductive substrate, drying and pressing, and connected to each other by a negative electrode lead 6. Each of the positive electrode plates 5 is configured by filling an active material paste containing nickel hydroxide as a main component in a porous conductive substrate, drying and pressing. A sealing body 7 is airtightly caulked and fixed to an opening of the battery case 1 through an insulating gasket 8. The sealing body 7 is a metallic sealing plate 10 having a valve hole 9 in the center, and an elastic body 1 arranged on the sealing plate 10 so as to close the valve hole 9.
1 and a positive electrode terminal plate 12 fixed on the sealing plate 10 so as to compress and cover the elastic body 11. A positive electrode lead 13 led out from each positive electrode plate 5 is connected to the lower surface of the sealing plate 10 by resistance welding. Comparative Example 1 A flat steel plate having a thickness of 4 mm and a nickel plating layer of 4 μm formed on both surfaces of a steel plate base material having a thickness of 0.4 mm was deep-drawn into a square cylinder with a bottom, and then the opening was further expanded. Then, it was processed into a predetermined bottomed rectangular tube shape to prepare a battery case. Then
A rectangular nickel-cadmium storage battery was assembled in the same manner as in Example 1 except that the battery case was used. Comparative Example 2 First, a flat steel plate having a thickness of 0.4 mm is deep-drawn into a bottomed rectangular tube, and then the vicinity of the opening is further expanded to form a predetermined bottomed rectangular tube. Subsequently, a battery case was prepared by subjecting the entire bottomed rectangular tubular steel plate to nickel plating so that the plating thickness in the vicinity of the opening was 5 μm at the maximum and the plating thickness on the inner surface was 3 μm at the minimum. . Then, a rectangular nickel-cadmium storage battery was assembled in the same manner as in Example 1 except that the battery case was used. Comparative Example 3 First, a flat steel plate having a thickness of 0.4 mm is deep-drawn into a bottomed rectangular tube, and then the vicinity of the opening is further expanded to form a predetermined bottomed rectangular tube. Subsequently, the whole bottomed rectangular tubular steel plate was subjected to nickel plating treatment so that the plating thickness in the vicinity of the opening became 15 μm and the plating thickness on the inner surface became a minimum of 4 μm to prepare a battery case. Then, a prismatic nickel-cadmium storage battery was assembled in the same manner as in Example 1 except that the battery case was used.

Fifty batteries of each of Example 1 and Comparative Examples 1 to 3 were manufactured, and it was confirmed that the nickel plating was peeled off when the sealing body was sealed at the opening of the battery case by caulking. The results are shown in Table 1 below.

For each of the 50 batteries obtained in Example 1 and Comparative Examples 1 to 3, the temperature was 45 ° C. and the relative humidity was 85%.
After storing for 20 days under the conditions of 1, the generation of rust on the surface of the battery case was confirmed. The results are also shown in Table 1 below.

Further, with respect to each of 50 batteries of Example 1 and Comparative Examples 1 to 3, after fully charged, they were discharged to a battery voltage of 1 V at 5 CmA, and a discharge capacity (mAh) and an average discharge voltage (V) were measured. did. The product of the measured value of the discharge capacity and the measured value of the average discharge voltage was calculated, the average value was obtained, and the large current discharge characteristic was evaluated by setting the average value of the product in the battery of Example 1 as 100%. The results are also shown in Table 1 below.

[0020]

[Table 1]

As is clear from Table 1, in the battery of Example 1, since the plating thickness on the inner surface of the battery case was 4 μm or more, which was sufficient, the battery case and the negative electrode plate connected to the inner surface of the battery case were The resistance between the two becomes small and the large current discharge characteristics are excellent, and since the total plating thickness near the opening of the battery case is a reasonable maximum of 5 μm, plating separation does not occur at the time of sealing, and as a result, It can be seen that there is no rust in the battery case after storage.

On the other hand, in the battery of Comparative Example 1, rust was found in the battery case after storage. This is because the battery was assembled while the plating peeling that occurred during the production of the battery case was present. It can be seen that the battery of Comparative Example 2 is significantly inferior in the large current discharge characteristics. This is because the plating thickness on the inner surface of the battery case is insufficient, at least 3 μm, so that the resistance between the battery case and the negative electrode plate connected to the inner surface of the battery case is large. It can be seen that in the battery of Comparative Example 3, the plating of the battery case was peeled off at the time of sealing and rust was generated after storage.
This is because the plating thickness near the opening of the battery case is 15μ.
This is due to the fact that it was excessive with m.

Although the prismatic nickel-cadmium storage battery has been described in the above embodiment, the same effect can be obtained with other prismatic alkaline storage batteries such as nickel-hydrogen storage battery and nickel-zinc storage battery.

[0024]

As described in detail above, according to the present invention, a highly reliable prismatic alkaline battery having excellent battery characteristics such as a large current discharge characteristic and preventing rust from occurring in the battery case can be manufactured at low cost. A method of obtaining can be provided.

[Brief description of drawings]

FIG. 1 is a perspective view showing a battery case according to a first embodiment.

FIG. 2 is a cross-sectional view showing a prismatic nickel-cadmium storage battery of Example 1.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery case, 2 ... Electrode group, 3 ... Negative electrode plate, 4 ... Separator, 5 ... Positive electrode plate, 7 ... Sealing body.

Claims (1)

[Claims] 1. A step of forming a nickel-plated steel plate into a bottomed rectangular tube having an opening near the opening, and further nickel-plating the battery case to prepare a battery case. After accommodating the power generating element, the method of manufacturing a prismatic alkaline battery, comprising a step of caulking a sealing body to the opening of the battery case and sealing the sealing body.