JP2003187859A - Prismatic battery and method of manufacturing the same - Google Patents

Abstract

(57) [Problem] To provide a prismatic battery which solves the problem of a rectangular battery lacking in the sealing performance of a sealing portion and obtains the same sealing performance as a cylindrical battery, and a method of manufacturing the same. SOLUTION: A sealing plate 2 is formed by caulking an annular portion 9b of a lid plate 9 to be laser-welded to an open end of an outer can 1 formed in a cylindrical shape having a substantially square cross section and having a bottom through a gasket 8. It is attached. Since the circular sealing plate 2 can be caulked and fixed by the circular annular portion 9b, the structure becomes the same as the sealing structure of the cylindrical battery, and a rectangular battery having the same sealing performance as the cylindrical battery can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prismatic battery having a substantially rectangular cross section and a method for manufacturing the prismatic battery.

[0002]

2. Description of the Related Art As portable electronic devices have become smaller and more sophisticated, batteries, which are power sources thereof, have been required to have smaller size and higher capacity. The form of the battery can be roughly classified into a cylindrical type and a square type, and the cylindrical type is widely used because it is excellent in productivity and cost can be reduced. However, since the cross-sectional shape is circular,
Dead space becomes large when a plurality is arranged,
Prevents device miniaturization. On the other hand, the prismatic battery has less dead space even when a plurality of prismatic batteries are arranged, and is suitable for downsizing of equipment. However, the prismatic battery has a problem that the sealing property of the sealing portion is lower than that of the cylindrical battery, and the reliability after long-term storage or long-term use is poor. The deterioration of the hermeticity causes leakage of the electrolytic solution, which not only deteriorates the storage characteristics and life characteristics of the battery but also relates to safety, and therefore improvement is desired.

FIG. 7 is a sectional view of a cylindrical alkaline storage battery, in which a positive electrode plate 55 and a negative electrode plate 56 are wound with a separator 57 in a bottomed cylindrical outer can 51. The group is housed together with the electrolytic solution, and the open end of the outer can 51 is sealed by the sealing plate 52. An annular groove portion 51a is formed on the opening end side of the outer can 51 so as to be convex inward, and a sealing plate 52 having a gasket 58 attached to the periphery thereof is arranged on the internal convex portion formed by the annular groove portion 51a. Then, the gasket 58 is compressed by the crimping process of bending the open end of the outer can 51 inward, and the open end of the outer can 51 is sealed. Since the gasket 58 is compressed to about 50 to 90% by volume by caulking, the repulsive elastic force of the gasket 58 improves the airtightness of the battery. Moreover, the gasket 58 electrically insulates between the outer can 51 forming the negative electrode terminal and the sealing plate 52 forming the positive electrode terminal. Further, the sealing plate 52 has an explosion-proof structure, and when a gas is generated in the outer can 51 to cause an abnormal increase in the internal pressure in the event of an abnormality such as a short circuit or overcharge, a synthetic material disposed in the terminal cap 54 is provided. The rubber valve body 53 is prevented from deforming and releasing gas to the outside from a discharge port (not shown) to prevent the battery from bursting.

FIG. 8 shows the exterior of a prismatic alkaline storage battery, and FIG.
Shows the cross section. As shown in FIG. 8, in an outer can 61 that is formed in a square tubular shape with a bottom and has an opening end side expanded,
An electrode plate group 73 in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween is housed together with an electrolytic solution, a gasket 68 and a sealing plate 62 are arranged in the expanded portion of the outer can 61, and the outer can 61 is opened. The gasket 68 is compressed by the crimping process of bending the ends inward, and the outer can 61 is sealed by the sealing plate 62. The valve body 63 is arranged in the terminal cap 64 of the sealing plate 62 to form an explosion-proof structure when the internal pressure rises abnormally.

[0005]

In the case of a prismatic battery, when the open end is caulked to seal the outer can 61,
As shown in FIG. 8, there is a problem in that the sealing performance is deteriorated in the straight portion 61c, and the corner portion 61d is subject to a shrinkage or a distortion to reduce the sealing performance of the battery. Further, when the side surface of the outer can 61 bulges outward when the internal pressure temporarily rises due to rapid charging or the like, a gap is generated in the straight portion 61c having a low sealing property, and the hermeticity is impaired.

In order to prevent the above-mentioned deterioration of the hermeticity, Japanese Patent Application Laid-Open No. 8-195203 discloses a structure in which a bridge plate for reinforcing the outer can is provided. However, even if the bridge plate is provided, the hermeticity does not reach that of the cylindrical battery, and the internal space of the battery is reduced by the bridge plate, which leads to a decrease in the capacity density of the battery.

The present invention was devised in view of the problems of the prismatic battery according to the prior art, and a prismatic battery in which the hermeticity of the prismatic battery is improved to a level equivalent to that of a cylindrical battery and its manufacture. To provide a method.

[0008]

In order to achieve the above object, the first invention of the present application is such that a power generating element is housed in a metal outer can formed in a bottomed cylindrical shape having a substantially quadrangular cross section. A rectangular battery in which an open end of an outer can is sealed by a lid plate formed in an outer shape corresponding to a cross-sectional shape of the outer can, wherein a circular opening formed in the center of the lid plate has an external It is characterized in that a circular sealing plate having a connection terminal is caulked and fixed via a gasket.

According to the above construction, since the circular sealing plate can be caulked and fixed to the circular opening through the gasket, the caulking sealing is ensured over the entire circumference, and the cylindrical battery is a prismatic battery. It is possible to obtain the same hermeticity.

In the above structure, the lid plate has an outer shape corresponding to the cross-sectional shape of the outer can, and a lid having a circular opening formed in the center thereof, and a peripheral edge of the opening to the inside or the outside of the outer can. It can be configured by providing an annular portion extending in a cylindrical shape, and the sealing plate can be caulked and fixed by the annular portion.

In the above structure, the periphery of the lid plate is laser-welded to the opening end of the outer can to seal the opening end of the outer can, and the sealing plate is fixed in a circular shape by caulking to improve the sealing property. The state can be maintained by welding the lid, and laser welding is a suitable means for welding.

Further, the annular portion of the lid plate is formed toward the inside of the outer can, and the caulking fixing portion of the sealing plate is located inside the outer can, so that the prismatic battery has a reduced height. The annular portion of the lid plate is formed toward the outside of the outer can, and the caulking fixing portion of the sealing plate is located outside the outer can. Therefore, the battery capacity can be increased.

Further, in the method for manufacturing a prismatic battery according to the second aspect of the present invention, the power generating element is housed in a metal outer can that is formed in a bottomed tubular shape having a substantially quadrangular cross section. A circular sealing plate is caulked and fixed to the opening of the lid formed in an outer shape corresponding to the cross-sectional shape and having a circular opening at the center, and the lid is attached to the opening end of the outer can. It is characterized in that the outer can is hermetically sealed by welding the periphery of the.

According to the above method of manufacturing the prismatic battery, the circular sealing plate is caulked and fixed to the circular opening formed in the lid through the gasket, so that the sealing plate is insulated from the lid. It is possible to manufacture a prismatic battery that has a reliable sealing property and by welding the lid body to the open end of the outer can has a sealing property equivalent to that of the cylindrical battery.

In the above manufacturing method, a ridge portion is formed toward the center on the circumference of an annular portion extending in a cylindrical shape from the peripheral edge of the opening formed in the lid plate, and the ridge portion is formed on the ridge portion. By arranging a circular sealing plate through a gasket and bending the end of the annular part inward to caulk and fix the sealing plate, the same caulking sealing structure as the cylindrical battery is obtained, and the lid body is packaged. By laser welding to the can, a rectangular battery can be obtained with the same sealing performance as a cylindrical battery.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.
The embodiments described below are examples of embodying the present invention and do not limit the technical scope of the present invention.

FIG. 1 shows the external appearance of the prismatic battery according to this embodiment, which is constructed as a nickel-hydrogen storage battery. The outer can 1 of this prismatic battery is formed into a bottomed cylinder having a square cross section with arcs at its corners, and an opening end thereof is fitted with a sealing plate 2 provided with a terminal cap 4 serving as a positive electrode terminal. It is sealed by the cover plate 9 formed.

As shown in FIG. 2 as a sectional view, the outer can 1
An electrode plate group 13 in which a positive electrode plate and a negative electrode plate are wound via a separator is housed together with an electrolytic solution, a negative electrode current collector 11 is arranged below the electrode plate group 13, and a positive electrode plate is provided above the electrode plate group 13. Current collector 1
0 is set. The electrode plate group 13 is fixed in the outer can 1 by an insulating plate 14. The open end of the outer can 1 is sealed by laser welding the periphery of a lid plate 9 having a sealing plate 2 attached to the center thereof to the outer can 1. The positive electrode plates constituting the electrode plate group 13 are connected to the positive electrode current collector 10, and the positive electrode lead 12 connected to the positive electrode current collector 10 is connected to the sealing plate 2 to provide a terminal cap provided on the sealing plate 2. 4 is a positive electrode terminal of the battery. Also, the electrode plate group 13
The negative electrode plate constituting the battery is connected to the negative electrode current collector 11, and the negative electrode current collector 11 is connected to the inner surface of the outer can 1 so that the outer can 1 serves as the negative electrode terminal of the battery.

The sealing plate 2 is attached by caulking to a cover plate 9 formed as shown in FIG. Lid plate 9
Is provided with a lid portion 9a formed in an outer diameter shape corresponding to the cross-sectional shape of the outer can 1, and an annular portion 9b in which the center of the lid portion 9a is circularly extended toward the inner side of the outer can 1. Formed,
The sealing plate 2 is arranged in the annular portion 9b via the gasket 8, and the gasket 8 is compressed by the crimping process of bending the opening end of the annular portion 9b inward, and the sealing plate 2 is attached to the lid plate 9. A valve port 2a communicating with the inside of the outer can 1 is formed in the center of the sealing plate 2, and is normally sealed by a valve body 3 arranged in a terminal cap 4, but gas is generated due to a short circuit or overcharge. When the pressure inside the outer can 1 rises abnormally and the abnormal internal pressure reaches the valve body 3 through the valve opening 2a, the valve body 3 made of synthetic rubber is deformed to remove the gas from the valve opening 2a. It is discharged to the outside from an exhaust hole (not shown) provided in the terminal cap. The explosion-proof structure of the valve element 3 prevents the battery from bursting when an abnormal internal pressure occurs.

In the prismatic battery having the above structure, since the sealing plate 2 is attached by crimping the circular annular portion 9b, a sealing state equivalent to that of the cylindrical battery can be obtained, which is a problem of the prismatic battery. The deterioration of the hermeticity at the straight part and the corner part, which was present, is solved.

Next, a method of manufacturing the prismatic battery having the above structure will be described with reference to FIG. Incidentally, S shown in FIG.
1, S2 ... are step numbers indicating the manufacturing procedure,
It matches the number added to the text.

First, an annular groove 9c which is convex inward is formed on the annular portion 9b forming the cover plate 9 by using a grooved roller (S1). The annular groove portion 9c can be easily formed by pressing the grooved roller against the outer peripheral surface of the annular portion 9b while rotating the cover plate 9. Next, the sealing plate 2 is placed on the convex portion formed in the ring shape by the annular groove 9c in the annular portion 9b via the gasket 8 (S
2) Then, the sealing plate 2 is attached to the cover plate 9 by crimping in which the open end of the annular portion 9b is bent inward (S3).

The electrode plate group 13 is formed by winding a positive electrode plate and a negative electrode plate with a separator interposed therebetween and forming a prismatic shape corresponding to the inner shape of the outer can 1. The positive electrode plate was prepared by filling a foam metal porous body with a paste containing nickel hydroxide as an active material and additives such as a conductive agent and a CMC aqueous solution, followed by a drying step, a rolling step, and a cutting step. A strip-shaped non-sintered nickel positive electrode plate, the negative electrode plate was formed by applying a paste prepared by kneading a hydrogen storage alloy together with a binder onto a punching metal core material, and then performing a drying process, a rolling process, and a cutting process. It was used as an occlusion alloy electrode. Electrode plate group 13 formed in this way
The negative electrode current collector 11 is arranged on the lower side and the positive electrode current collector 10 is arranged on the upper side, and the positive electrode lead 12 is welded to the positive electrode current collector 10 and housed in the outer can 1 (S4).

Next, the positive electrode lead 12 drawn from the inside of the outer can 1 is welded to the sealing plate 2 attached to the lid plate 9 in the step S3, and the electrode plate group 13 of the outer can 1 is welded.
The insulating plate 14 is pushed into the upper part, and the cover plate 9 is attached to the opening end of the outer can 1.
Are fixed by laser welding (S5).

Next, a predetermined amount of electrolytic solution is injected into the outer can 1 through a valve opening 2a formed in the center of the sealing plate 2, and the valve opening 2 is opened.
The valve body 3 is placed on a, and the terminal cap 4 is welded to the sealing plate 2 to seal the outer can 1 (S6) to form a prismatic nickel-hydrogen storage battery (S7). Complete by discharging.

With respect to the prismatic battery manufactured by the above procedure, the result of verifying the hermeticity by comparison with the prismatic battery having the conventional structure shown in FIG. 9 and the cylindrical battery will be described below. Both are constructed as nickel-hydrogen storage batteries having a nominal voltage of 1.2V.

100 prismatic batteries according to the present invention, 100 prismatic batteries having a conventional structure as a comparative example, and 100 conventional cylinder batteries were prepared and left at high temperature under the following conditions. Perform a storage test to verify the leak rate of each battery.

After the remaining capacity of each battery was completely discharged, a discharge capacity of 120 was obtained by applying a current equivalent to 1C.
A cycle of charging an amount of electricity of 1% and discharging with a current equivalent to 1 C until the battery voltage reached 0.8 V was repeated 100 times in a normal temperature atmosphere, and then left in a charged state in an atmosphere of 80 ° C. for 20 days. . The liquid leakage generation rate obtained by this high temperature storage test is shown in Table 1.

[0029]

[Table 1] As shown in Table 1, no leakage occurred in the prismatic battery according to the present invention even after the high temperature storage test.
It exhibits the same level of liquid leakage resistance as a cylindrical battery. On the other hand, in the conventional rectangular battery as a comparative example, 8 out of 100
It was confirmed that liquid leaked to each piece and that liquid was leaking from the caulking seal part. From this verification result, since the prismatic battery using the sealing structure of the present invention has excellent sealing performance, the electrolyte does not leak even after long-term use or long-term storage, and the reliability is equivalent to that of the cylindrical battery. A prismatic battery with is realized.

In the structure of the prismatic battery described above, the lid plate 9 is formed by separately forming the lid portion 9a and the annular portion 9b as shown in FIG. 5, and integrating them by welding. You can also do it.

Further, as shown in FIG. 3, if the annular portion 9b of the cover plate 9 is configured to face upward, the total height of the battery increases, but the volume occupied by the sealing plate 2 in the outer can 1 decreases. The volume of the electrode plate group 13 can be increased, and the battery capacity can be increased.

In the above embodiment, the nickel-hydrogen storage battery is used as an example. However, the same effect can be obtained regardless of whether the battery is a primary battery or a secondary battery.

[0033]

As described above, according to the present invention, the deterioration of the hermeticity of the sealing portion, which was a problem of the prismatic battery, is improved, and the hermeticity equivalent to that of the cylindrical battery is obtained, so that long-term storage It is possible to provide a prismatic battery having high reliability without leakage of the electrolyte even after long-term use.

[Brief description of drawings]

FIG. 1 is a perspective view showing the external appearance of a prismatic battery according to an embodiment.

FIG. 2 is a sectional view of the same battery.

FIG. 3 is a sectional view showing a modified example of the same battery.

FIG. 4 is a perspective view showing a configuration of a cover plate.

FIG. 5 is a perspective view showing another configuration of the cover plate.

FIG. 6 is a process diagram showing a manufacturing procedure of a prismatic battery.

FIG. 7 is a cross-sectional view showing the configuration of a cylindrical battery.

FIG. 8 is an exploded perspective view showing the configuration of a conventional prismatic battery.

FIG. 9 is a cross-sectional view of the same prismatic battery.

[Explanation of symbols]

1 exterior can 2 Seal plate 8 gasket 9 Lid plate 9a lid 9b Ring part 13 electrode group

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Masahiko Kato             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Boki Yoshihiro             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5H011 AA13 BB03 CC06 DD13 DD15                       FF02 GG02                 5H028 AA01

Claims (8)

[Claims] 1. A power generating element is housed in a metal outer can, which is formed into a bottomed tubular shape having a substantially quadrangular cross section, and an open end of the outer can has an outer shape corresponding to the cross section of the outer can. A rectangular battery sealed with a lid plate, wherein a circular opening plate formed with an external connection terminal is caulked and fixed to a circular opening formed in the center of the lid plate through a gasket. A prismatic battery characterized in that 2. The lid plate has an outer shape corresponding to the cross-sectional shape of the outer can and having a circular opening formed in the center thereof,
The prismatic battery according to claim 1, further comprising: an annular portion that extends from the peripheral edge of the opening to the inside or outside of the outer can in a cylindrical shape. 3. The prismatic battery according to claim 1, wherein the opening end of the outer can is sealed by laser welding the periphery of the lid plate to the opening end of the outer can. 4. The prismatic battery according to claim 1, wherein the annular portion of the lid plate is formed toward the inside of the outer can, and the caulking fixing portion of the sealing plate is located inside the outer can. 5. The prismatic battery according to claim 1, wherein the annular portion of the lid plate is formed toward the outside of the outer can, and the caulking fixing portion of the sealing plate is located outside the outer can. 6. A power generating element is housed in a metal outer can, which is formed in the shape of a bottomed cylinder having a substantially quadrangular cross section, is formed in an outer shape corresponding to the cross section of the outer can, and has a circular opening in the center. A circular sealing plate is caulked and fixed to the opening of the lid in which the portion is formed via a gasket, and the periphery of the lid is welded to the opening end of the outer can to seal the inside of the outer can. And a method for manufacturing a prismatic battery. 7. A ridge portion directed toward the center is formed on the circumference of an annular portion extending in a cylindrical shape from the peripheral edge of the opening formed in the lid plate, and a gasket is provided on the ridge portion. 7. The method for manufacturing a prismatic battery according to claim 6, wherein a circular sealing plate is arranged, and an end portion of the annular portion is bent inward to fix the sealing plate by caulking. 8. The method for manufacturing a prismatic battery according to claim 5, wherein the opening end of the outer can and the lid plate are welded by laser welding.