JPH08190930A - Square storage battery - Google Patents

Abstract

PURPOSE: To provide a square storage battery which is easy to manufacture and has high shock resistance from the standpoint of electrical connection of a negative plate and a battery can. CONSTITUTION: A negative plate 1 prepared by applying slurry comprising usual hydrogen storage alloy powder, a binder, and water to a perforated steel plate, drying the slurry, then pressing is used. Substrate exposed parts 2 are formed on both sides of the negative plate 1, and the lateral width of the negative plate 1 containing the exposed parts 2 is made larger than the inner dimension corresponding to a battery can 5. Four negative plates 1 and three nickel positive plates each wrapped with a separator are mutually stacked to constitute an electrode plate group, and the electrode plate group is inserted into a battery can 5 so that the corner round parts 6 of the negative plates 6 are brought into contact with an opening of the battery can 5 at the start of insertion. 30wt.% KOH aqueous solution is poured in the battery can 5 as an electrolyte, a lead terminal welded of the nickel positive plates is welded to a positive terminal of a cover, then the cover is fixed to the can, and a battery is sealed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prismatic storage battery such as a nickel-hydrogen storage battery or a nickel-cadmium storage battery.

[0002]

2. Description of the Related Art In recent years, with downsizing of electric equipment, a demand for a prismatic storage battery, which is more advantageous in terms of volume efficiency than a cylindrical storage battery, is increasing. In general, a prismatic storage battery has a positive electrode plate and a negative electrode plate laminated via a separator, is inserted into a battery can, electrically connects the positive electrode plate and a lid that is a positive electrode terminal, and is a negative electrode plate and a negative electrode terminal. It is manufactured by electrically connecting to a battery can and injecting an electrolytic solution into the battery can.

Conventionally, as a method for electrically connecting a negative electrode plate of a prismatic storage battery and a battery can as a negative electrode terminal, Japanese Patent Application Laid-Open No. 1-21 has been used.
As described in Japanese Patent Laid-Open No. 00552, a method has been proposed in which a negative electrode plate is bent in a U shape and the bent portion is pressed against the bottom surface of the battery can. As shown in FIG. 4, the negative electrode plate 1 is provided with a base body exposed portion 2a at the center thereof, and the electrode plate group is formed by bending the negative electrode plate 1 into a U shape as shown in FIG. By electrically pressing the portion 2a against the bottom surface of the inside of the can, electrical connection is obtained at the bottom surface of the inside of the battery can.

[0004]

However, in the above conventional electrical connection method, the negative electrode plate is replaced by about 2 times the positive electrode plate.
It is necessary to double the length and bend it accurately into a U-shape from the center. In general, a prismatic sealed storage battery has a shape close to what is called a chewing gum shape, so the negative electrode plate must be extremely elongated, and it is very difficult to bend it accurately from the center, which significantly impairs the yield during manufacturing. Met. In addition, even if the negative electrode plate bent in a U shape is pressed against the inner bottom surface of the battery can, if a shock is applied at the stage of using as a storage battery or during the operation in the manufacturing process after inserting the electrode plate group into the battery can, There has been a problem that the electrode plate group inserted in the can moves up and down, making electrical connection uncertain. If the battery is used in that state, the capacity of the negative electrode will be extremely reduced, and not only the capacity of the battery will be reduced, but also the charge reserve part and discharge reserve part of the negative electrode will not be secured, so the charge / discharge performance, especially the battery internal pressure at the time of charging, will decrease. There is a risk of rising and leaking. An object of the present invention is to obtain a prismatic storage battery which is easy to manufacture and has excellent impact resistance from the viewpoint of electrical connection between the negative electrode plate and the battery can.

[0005]

In order to solve the above problems, in a prismatic storage battery according to the present invention, a positive electrode plate and a negative electrode plate are stacked via a separator to form an electrode plate group, which is used as a metal battery can. In the case of being housed, the width of the negative electrode plate is larger than the inner size of the battery can in at least part of the height direction of the negative electrode plate. In addition, it is preferable that the lower end of the negative electrode has a lateral width equal to or smaller than the inner dimension of the battery can, and has a portion where the lateral width of the negative electrode plate increases from that point as a base point toward the upper end.

Here, the lower end of the negative electrode plate refers to a portion which is first inserted when the electrode plate group is housed in the battery can and is present on the bottom surface of the battery can after being housed in the battery can. The lateral width of the negative electrode plate is the length of the electrode plate in the direction perpendicular to the electrode plate height direction from the lower end to the upper end.

[0007]

The operation of the present invention will be described below with reference to the drawings. The negative electrode plate 1 shown in FIG. 3 has a width W ₁ of the battery can 5 shown in FIG.
Is larger than the inner dimension W ₂ in the direction in which the negative electrode plate 1 is stored. When this negative electrode plate 1 is laminated so as to face the positive electrode plate with the separator interposed therebetween and the formed electrode plate group is housed in the battery can 5 shown in FIG. 2, the negative electrode plate side portion is pressed against the spring as shown in FIG. It contacts the inner wall of the battery can 5 with force, and an electrical connection between the negative electrode plate and the battery can is obtained. In this state, even if the electrode plate group moves in the vertical direction due to an impact from the outside of the battery can, the contact portion only moves and the electrical connection is not lost. Further, even when the electrode plate group is moved in the left-right direction, at least the contact portion on one side does not lose electrical connection, so that the performance as the storage battery is not impaired. Further, the present invention does not require a complicated operation such as bending of the electrode plate, which is disclosed in Japanese Patent Laid-Open No. 1-200552, and therefore can be easily manufactured. Also, FIG.
As shown in FIG. 6, the horizontal width of the lower end of the negative electrode plate 1 is less than or equal to the inner dimension of the battery can, and from that point as a base point, the horizontal width of the negative electrode plate increases toward the upper end, that is, the corner rounded portion 6 here. By providing the electrode plate, the operation when inserting the electrode plate group into the battery can becomes easy.

[0008]

EXAMPLE An example of the present invention will be described below. (Embodiment) The negative electrode plate 1 shown in FIG. 3 has a perforated plate made of nickel plated with iron as a base, and a slurry composed of a known hydrogen storage alloy powder, a carboxymethylcellulose binder and water. Was applied, dried and pressed. The exposed base portions 2 are provided at both ends of the negative electrode plate 1, and the horizontal width W ₁ of the negative electrode plate 1 including the exposed base portion 2 is 15.0 mm. The width direction of the portion not including the exposed base portion 2 and coated with the slurry. Was 13.0 mm, and the width of the exposed base portion 2 was 1.0 mm. Further, a rounded corner portion 6 having an R of 1.0 mm was provided at the lower end of the exposed base portion 2. The battery can 5 shown in FIG. 2 has an inner dimension W ₂ corresponding to the width W ₁ of the negative electrode plate 1 of 14.8.
mm. A known nickel electrode was used for the positive electrode plate 3, and a metallic nickel portion as a conductive terminal was provided on the upper end portion thereof.
The electrode plate size was the same as the size of the portion of the electrode plate 1 on which the slurry was applied. This was wrapped in a bag with a known separator 4 except for the metal nickel portion. Four negative electrode plates 1 and three nickel electrodes wrapped with separators are alternately stacked, and the separators are further stacked one by one on the outside of the electrode plate group in order to secure a large amount of retained electrolyte. The group was made up. At this time, the metallic nickel portions as the conductive terminals at the upper end of the nickel electrode were welded so as to be integrated. In this state, the electrode plate group was inserted into the battery can 5 such that the rounded corners 6 of the electrode plate 1 first contacted the can mouth of the battery can 5. The cross-sectional view of the battery can after that is shown in FIG. The battery can with this electrode group inserted in the electrolyte 3
A 0 wt% KOH aqueous solution was injected, the conductive terminal of the welded nickel electrode and the positive electrode terminal of the lid were welded, and then the lid was covered and sealed to prepare a battery of this example.

(Conventional example) Except that the base body exposed portion is not provided at both ends in the width direction of the negative electrode plate, the base body exposed portion 2a is provided at the center as shown in FIG. 4, and the width of the negative electrode plate 1 is 13.0 mm. The negative electrode plate 1 was manufactured by the method described in the above example. The exposed portion 2a of the base body at the center is bent in a U shape so that the nickel electrode is wrapped with a separator interposed therebetween.
A battery was manufactured under the same conditions as in the above-mentioned example except that the electrode plate group as shown in FIG. This is the battery of the conventional example.

Each of the thus-obtained batteries of the example and the conventional example was prepared in 1000 pieces, and 500 pieces in each of them were subjected to a horizontal vibration test and a vertical vibration test. In each direction, the vibration was 4 mm in amplitude, the frequency was 16.7 Hz, and the ambient temperature was 20 ° C. ± 2 ° C. Vibration test for 3 hours, 6 hours, 1
Table 1 shows the occurrence rate of defective conduction between the negative electrode plate and the battery can after 2 hours. Whether or not the poor continuity occurred was determined by conducting a vibration test for each time, removing the lid, and measuring the electric resistance between the negative electrode plate and the battery can. As shown in Table 1, it can be seen that the battery of the conventional example is apt to cause conduction failure particularly when vibrating in the vertical direction.
On the other hand, the battery of this example had no conduction failure in any of the vibration directions.

[0011]

[Table 1]

In this embodiment, a negative electrode plate as in the conventional example is
Since the length of the positive electrode plate is about twice that of the positive electrode plate, it is not necessary to accurately bend it in the U-shape from the center,
It could be manufactured easily.

In the present embodiment, the corner rounded portion is provided at the lower end of the negative electrode plate to facilitate the operation when inserting the electrode plate group larger than the inner size of the battery can into the battery can. Even if the electrode plate group including the negative electrode plate was inserted into the battery can while being compressed in the lateral direction, the operation could be easily performed. Also, in addition to making the lower end of the negative electrode plate into a rounded corner, the horizontal width of the lower end of the negative electrode plate is less than or equal to the inner dimension of the battery can. The same effect as that of the present embodiment was obtained by adopting a configuration having a portion that becomes larger in size. In this example, a hydrogen storage alloy electrode was used as the negative electrode plate, but the same effect was obtained with other commonly used negative electrode plates such as cadmium electrode and zinc electrode.

In this embodiment, the negative electrode plate was provided with the exposed base portion, but the effect of the present invention could be obtained without providing it. In this embodiment, a separator having a bag shape is used to enclose the positive electrode. However, this need not be the case, and the negative electrode plate and the positive electrode plate may not be short-circuited. Although a sealed battery was manufactured in this embodiment, the same effect as that of the present invention can be obtained even in the open battery.

In the structure of the electrode plate group using three or more negative electrode plates as in the above embodiment, if the separator is not used outside the electrode plate group, the negative electrode plates on both end surfaces are always connected to the battery can. To be done. However, if it is attempted to achieve the connection between the negative electrode plate located inside the electrode plate group and the battery can by means other than the means for bending the negative electrode plate into a U-shape at the center (conventional example), the configuration of the present invention causes a manufacturing process. It is extremely effective while being small.

[0016]

As described above, the prismatic storage battery according to the present invention can be easily manufactured, and can have excellent impact resistance in terms of electrical connection between the negative electrode plate and the battery can. did it.

[Brief description of drawings]

FIG. 1 is a view showing a state in which an electrode plate group is housed in a battery can in a prismatic storage battery of the present invention.

FIG. 2 is an external view of a battery can used in this example.

FIG. 3 is an external view of a negative electrode plate used in this example.

FIG. 4 is an external view of a conventional negative electrode plate.

FIG. 5 is an external view of a conventional electrode plate group.

[Explanation of symbols]

1 is a negative electrode plate, 2 is a substrate exposed portion, 2a is a central substrate exposed portion, 3 is a positive electrode plate, 4 is a separator, 5 is a battery can, 6 is a rounded corner at the lower end of the negative electrode plate, and W ₁ is a negative electrode plate. Width, W ₂ is the inner size of the battery can corresponding to the width of the negative electrode plate.

Claims (2)

[Claims] 1. A prismatic storage battery in which a positive electrode plate and a negative electrode plate are stacked via a separator to form an electrode plate group, and the electrode plate group is inserted into a metal battery can. In the prismatic storage battery, the horizontal width of the negative electrode plate is the height direction of the negative electrode plate. A prismatic storage battery, characterized in that it is at least partially larger than the inner size of the battery can. 2. The width of the lower end of the negative electrode plate is less than or equal to the inner dimension of the battery can.
The prismatic storage battery according to claim 1, wherein the prismatic storage battery has a portion where the lateral width of the negative electrode plate is large.