JP2002093382A - Storage battery and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a storage battery with improved sealing property between a metal can and a packing, with the type of the storage battery sealed by calking. SOLUTION: With the storage battery which has a group of electrodes 1 mounted consisting of an anode plate 1a, a cathode plate 1b and a separator 1c, a opening sealing body 3 is fitted inside an opening end part 2b of a metal can 2 with electrolyte solution injected through a circular packing 4, and an outer periphery edge of the opening sealing body 3 is calked and fixed with an opening edge part 2b of the metal can 2 to seal an opening part 2a of the metal can 2, a plurality of grooves 5 extending along the direction orthogonal to an opening direction of the metal can are formed at a part corresponding to the packing 4 on the inside face of the opening edge part 2b of the metal can 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sealed storage battery and a method for manufacturing the same.

[0002]

2. Description of the Related Art In this type of storage battery, the opening of a metal can is sealed with a sealing body. The sealing method includes a laser between the metal can and the sealing body depending on the shape of the battery. -It is roughly classified into a method of welding by irradiation of light or the like, and a method of caulking and closing the sealing body at the opening end of the metal can. The sealing method by welding has a problem in that a considerable investment is required for capital investment, fine control of the welding state is required, the welding time is relatively long, and the production cost is high. On the other hand, the crimping method has the advantages that the equipment cost is low and that it can be processed relatively easily. In general, this method is frequently used.

A storage battery according to this crimping prevention method is shown in FIG.
As shown in FIG. 3, a positive electrode plate 101a, a negative electrode plate 101b, and a separator 101 are placed in a metal can 102 into which an electrolytic solution is injected.
c, and a sealing body 103 is provided in the opening end 102a of the metal can 102 via an annular packing 104, and the opening end 102a is packed against the outer peripheral edge of the sealing body 103. , And the opening end 102a of the metal can 102 is brought into close contact with the sealing body 103 via the packing 104,
This seals the opening 102b of the metal can 102.

In this sealing method, it is necessary to prevent liquid leakage from a boundary surface existing between the open end 102a of the metal can 102, the sealing body 103 and the packing 104.
In general, a metal can is applied to the inner surface of the open end 102a of the metal can 102, the peripheral portion of the sealing body 103, and the inner and outer surfaces of the packing 104, with a sealant mainly composed of pitch or tar being applied. The caulking process of 102 is performed.

[0005]

As described above, in the storage battery sealed by caulking, at the boundary surface between the sealing body 103 and the packing 104, the edge portions 103a, 103a above and below the peripheral edge of the sealing body 103 are packed. Because it digs into the inner surface of 104, both 103, 104
Contact pressure is relatively large. However, the inner surface of the open end 102a of the metal can 102 and the outer surface of the packing 104 are in a curved surface contact state, the contact pressure is relatively small, and there is a possibility that the leakage of the electrolytic solution may proceed from this portion.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a storage battery of a type sealed by caulking, in which the sealing property between a metal can and a packing can be improved. .

[0007]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a locally high contact pressure has been found between the opening end of the metal can and the packing (interface). Even if it cannot be obtained, the sealing function is strengthened by forming a plurality of grooves along the direction perpendicular to the opening direction on the inner surface of the opening end of the metal can to increase the contact area at the interface between them. They have found out what can be done and have completed the present invention.

That is, according to the present invention, an electrode group comprising a positive electrode plate, a negative electrode plate and a separator is loaded, and a sealing body is provided via an annular packing in an opening end of a metal can into which an electrolytic solution has been injected. In the storage battery in which the outer peripheral edge of the sealing body is crimped at the open end of the metal can and the opening of the metal can is sealed, a portion of the inner surface of the open end of the metal can that corresponds to packing is provided with a metal can. According to a storage battery, a plurality of grooves extending along a direction perpendicular to the opening direction are formed.

According to this invention, since the plurality of grooves extending along the direction perpendicular to the opening direction are formed on the inner surface of the open end of the metal can, the packing end is formed at the open end of the metal can via packing. In the state where the sealing body is caulked, the contact surface between the entire outer surface of the packing and the inner surface of the open end of the metal can becomes large. That is, since the creepage distance at the interface between the two is long, the sealing property is improved, and the leakage of the electrolyte is effectively prevented.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a partially cutaway front view showing an example of a storage battery of the present invention in a state before sealing.
Referring to FIG. 1, the storage battery includes an electrode group 1, a metal can 2, a sealing body 3, a packing 4, and an electrolyte (not shown).

The electrode group 1 comprises a positive electrode plate 1a mainly composed of a nickel hydroxide mixture, a negative electrode plate 1b mainly composed of a hydrogen storage alloy, and a separator made of a polypropylene non-woven fabric interposed between the two electrodes 1a and 1b. -Metal can 2
Is loaded inside. The metal can 2 is made of, for example, an iron-made bottomed cylinder and also serves as a negative electrode terminal. On the inner surface of the upper part of the metal can 2, an annular projection 9A for placing packing is provided.
Is formed, and an electrolyte is injected into the inside of the electrode group 1 in a loaded state.

The sealing body 3 is for closing the opening 2a of the metal can 2 and is formed, for example, in a circular shape in plan view and disposed in the opening end 2b.
Is caulked at the opening end 2b of the opening, and constitutes a positive electrode terminal in a sealed state. The packing 4 is formed in an annular shape having an L-shaped cross section with, for example, a synthetic resin such as nylon, and the sealing body 3 is fitted therein.

On the inner surface of the open end 2b of the metal can 2, a sealant such as a pitch is applied to a portion corresponding to the outer surface of the packing 4. As shown in FIG. 2, a portion of the inner surface of the opening end 2b of the metal can 2 facing the packing 4 extends in a direction perpendicular to the opening direction of the metal can 2 (ie, in the circumferential direction). A plurality of grooves 5 are formed. As shown in FIG. 3, the upper end of the annular canister 9A of the metal can 2, that is, the open end 2b is curled inward in the radial direction as shown in FIG. I have.

In such a configuration, in a state where the sealing body 3 is caulked by the opening end 2b of the metal can 2,
The upper and lower edge portions 3a, 3a of the peripheral portion of the sealing body 3 bite into the inner surface of the packing 4, and locally a large contact pressure is generated between the two, and the liquid tightness of this portion is sufficiently ensured. . Further, a plurality of grooves 5 extending along the circumferential direction is formed in a portion of the inner surface of the open end 2b of the metal can 2 corresponding to the packing 4, so that the entire outer surface of the packing 4 and the metal can 2 are formed. The contact area with the inner surface of the opening end portion 2b of the opening becomes large, that is, the creeping distance with respect to the electrolytic solution at the interface between the two ends 4 and 2b increases, and the liquid tightness at this portion is also ensured. That is, in the above configuration, even if a large contact pressure cannot be locally obtained between the packing 4 and the open end 2b of the metal can 2, the sealing property with respect to the electrolytic solution can be enhanced.

Next, a method of manufacturing the storage battery having the above configuration will be described. First, a cylindrical metal can 2 is prepared, and a plurality of grooves are provided at appropriate intervals from the open end of the metal can 2 by using a lathe or the like on a packing facing portion on the inner surface of the open end 2b of the metal can 2. 5 is formed by cutting. At this time, burrs are generated on the inner surface of the metal can 2 by the above-mentioned cutting process. If the burrs are uniform over the entire circumference of the metal can 2, the burrs may be used for cutting into the packing 4. However, in most cases, the burrs are not uniform and may be damaged when the battery group 1 is loaded. Therefore, it is usually preferable to remove the burrs with a sandpaper or the like.

On the inner surface of the metal can 2, a rust-preventing plating layer, for example, a nickel plating layer (not shown) is formed. Since the plating layer may be peeled off during the formation of the groove 5, the groove 5 is formed on the metal can 2 before the plating layer is formed, and then the plating layer is formed. Is desirable. Thereby, the rust prevention function can be maintained. After forming the groove 5 in this manner, the electrode group 1 is placed in the metal can 2.
The annular projection 9A is formed on the inner surface of the metal can 2 by forming an annular recess 9 by drawing on the upper outer surface of the metal can 2 in this state.

Next, after injecting the electrolytic solution into the metal can 2, a sealing body 3 is provided together with the packing 4 in the upper end 2b of the metal can 2, and the sealing body 3 and the positive electrode plate 1a of the electrode group 1 are provided. And are electrically connected. Then, after applying a sealant such as a pitch to the outer peripheral surface of the packing 4, the opening end 2b of the metal can 2 is bent inward in the radial direction to hold the packing 4 on the peripheral edge of the sealing body 3. Then, the sealing body 3 is caulked and the opening 2a of the metal can 2 is sealed. At this time, the compression ratio of the packing 4 depends on the edge portion 3 of the sealing body 3.
In a and 3a, it is preferable to set 25 ± 2%.

According to such a manufacturing method, the packing opposing portion on the inner surface of the opening end is 0.2 mm from the opening end.
Approximately 20 grooves 5 each having a depth dimension (“A” in FIG. 2) of 0.05 mm and a width dimension (“B” in FIG. 2) of 0.1 mm were cut and formed. Can 2 (inner diameter 2 mm, wall thickness 0.3
5 mm) and a storage battery (comparative example) using a metal can having a conventional configuration in which the grooves 5 were not formed by cutting, are referred to as heat shock by the following method. A leak test was performed.

That is, at -40 ° C. for 1 hour and at 80 ° C. for 1 hour.
The time was set to one cycle, and this cycle was repeated 32 cycles, and the state of leakage of the electrolytic solution was examined by a rapid temperature change in a state where the discharged storage battery was placed with the positive electrode terminal facing upward in the atmosphere. As a result, in the storage battery of the comparative example, liquid leakage at the sealing portion was confirmed in 8 out of 100 inspections. However, in the storage battery of the above example, liquid leakage was found in all of the 100 inspections. Was not recognized. From this test result, it can be seen that the configuration of the present invention can greatly improve the leakage resistance of the storage battery.

[0020]

As described above, according to the present invention, a plurality of extending extending along the direction perpendicular to the opening direction of the metal can is provided on the inner surface of the opening end of the metal can for caulking the sealing body through packing. The formation of the groove increases the contact area between the entire outer surface of the packing and the inner surface of the open end of the metal can in the caulking-prevented state, so that the interface between the open end of the metal can and the packing is increased. As the creepage distance with respect to the electrolytic solution increases, leakage of the electrolytic solution can be effectively prevented.

When a plating layer is formed on the inner surface of the metal can, the rust on the inner surface of the metal can is prevented and the durability can be improved. However, prior to the formation of the plating layer,
By forming the above-mentioned grooves, there is no possibility of peeling of the plating layer during the processing of the grooves, and it is possible to reliably improve the durability by the plating layer.

[Brief description of the drawings]

FIG. 1 is a partially cutaway front view showing an example of a storage battery of the present invention before sealing.

FIG. 2 is an enlarged view showing a portion II in FIG.

FIG. 3 is a sectional view of a main part showing the storage battery in a state after sealing.

FIG. 4 is a sectional view of a main part showing a conventional storage battery.

[Explanation of symbols]

 Reference Signs List 1 electrode group 1a positive electrode plate 1b negative electrode plate 1c separator 2 metal can 2a opening 2b opening end 3 sealing body 4 packing 5 groove

Claims (3)

[Claims] 1. An electrode group comprising a positive electrode plate, a negative electrode plate and a separator is loaded, and a sealing body is provided through an annular packing in an opening end of a metal can into which an electrolytic solution has been injected. In a storage battery in which the outer peripheral edge of the sealing body is crimped to seal the opening of the metal can, a portion corresponding to packing on the inner surface of the opening end of the metal can is orthogonal to the opening direction of the metal can. A plurality of grooves extending along a direction of the storage battery. 2. The storage battery according to claim 1, further comprising a plating layer on an inner surface of the metal can. 3. A method of manufacturing a storage battery according to claim 2, wherein grooves are formed prior to forming the plating layer.