JPH0760673B2 - Sealed storage battery - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a sealed lead-acid battery such as a sealed lead-acid battery or a sealed alkaline battery, and more particularly to a thin sealed battery.

2. Description of the Related Art In recent years, as portable devices have become lighter, thinner, shorter, and smaller, there has been an increasing demand for thinner storage batteries used as their power sources. In response to these demands, a thin battery using a synthetic resin sheet as a battery case has been developed. Regarding the safety and reliability of these storage batteries, the following storage battery functions are required.

The battery should not be deformed or exploded by the gas generated during charging and discharging of the storage battery.

To suppress heat generation due to absorption reaction of oxygen gas generated from the positive electrode during charging at the negative electrode.

This is because the absorption reaction of the storage battery is promoted in the portable device where the ambient temperature is likely to rise, and the temperature of the storage battery rises, the current also increases, and heat escape may occur.

To release hydrogen gas generated from the negative electrode as soon as possible.

This is because hydrogen gas is not absorbed in the storage battery and is easily accumulated in the battery, and if a large amount of hydrogen gas is accumulated, there is a risk of explosion if a fire point should occur.

This is to prevent outside air from entering the storage battery.

This is because when outside air (especially oxygen gas) enters the storage battery, oxidation of the negative electrode (a phenomenon equivalent to discharging) occurs and the performance of the storage battery is significantly deteriorated.

Due to these problems, the safety valve must have a valve closing pressure as low as possible and ensure airtightness during depressurization.

Conventionally, as shown in FIG. 2, an anode plate 1, a separator 2,
In the sealed lead-acid battery in which the electrode plate group 11 including the negative electrode plate 3 is covered with the sheet 6 made of synthetic resin, the periphery of the sheet 6 is joined by leaving the unjoined portion 7 in a part of the sheet 6 (peripheral joining portion 5 ),
The unjoined portion 7 was faced in parallel with almost no gap, and this portion was used as a safety valve. Further, a synthetic resin reinforcing material 8 is attached and fixed to one side or both sides of the safety valve portion outside the seat 6 to prevent deterioration of the safety valve portion. [Hereinafter, referred to as (conventional product 1)] In Japanese Patent Laid-Open No. 63-174265, as shown in FIG.
The electrode plate group 11 is arranged between two sheets 6 made of synthetic resin to join the peripheral portions (peripheral joint portion 5), and the peripheral portion of the small hole 4 provided on one sheet 6 is connected to the other sheet 6. Was discontinuously joined (discontinuous joint 12) to form a safety valve. [Hereinafter, referred to as (conventional product 2)] Problems to be Solved by the Invention In conventional product 1 of the conventional sealed lead-acid battery, a heat seal or an impulse seal is used as a method for producing a joint, but the unjoined part is used. In order to form 7, the heat sealer and the impulse sealer needed a structure for forming the unbonded portion 7. Furthermore, a new material called the synthetic resin reinforcing material 8 is required, and the number of man-hours for attaching it by heat welding or an adhesive is also required, which causes a problem in production efficiency.
Further, although the safety valve is prevented from being deteriorated by attaching the synthetic resin reinforcing material 8, the opening pressure of the safety valve is high from the initial stage. If silicone oil is applied to this,
There is a problem that the valve opening pressure becomes higher.

In addition, the valve opening pressure of the conventional product 2 is low, but the battery case becomes thinner as the storage battery becomes thinner.
A safety valve having a lower opening pressure is desired. That is,
Since the small holes 4 are present only in the one sheet 6, only one sheet 6 is opened when the gas is discharged, and further, since the sheet 6 is present in the portion facing the small holes 4,
Silicone oil also accumulates in the small holes 4 and gas discharge is suppressed, resulting in a high valve opening pressure. In addition, the silicone oil accumulated in the small holes 4 easily closes the gas discharge path up to the small holes 4, and the valve opens at a high internal pressure, so that more gas remains in the battery. There is a fear. Further, after the two sheets 6 are joined together, a half-cut is made when the small holes 4 are formed in only one of the sheets 6, or one sheet 6 having the small holes 4 previously formed is joined to the other sheet having no small holes 4. There is also a possibility of problems in production efficiency such as accurate alignment at the time.

Means for Solving the Problems According to the present invention, an electrode plate group is disposed between two airtight sheets and the periphery of the airtight sheet is joined, and the two airtight portions are inside the peripheral joint portion. Is a sealed battery, wherein the safety sheets are joined discontinuously, and a safety valve portion is formed in a portion surrounded by the discontinuous joint portion and the peripheral joint portion, wherein the safety valve portion is The airtight sheet has a through hole communicating from the outer surface of the other airtight sheet to the outer surface of the other airtight sheet, and has oil between the inner surfaces of the two airtight sheets around the through hole. The periphery of each through hole of the airtight sheet is adhered by the oil, and each through hole passes through the gaps other than the discontinuous joints on the inner surfaces of the two airtight sheets to form the electrode plate group. It is characterized by being in communication with the part . The airtight sheet is a single or composite sheet of film-shaped synthetic resin or metal foil.

Operation The present invention provides a sealed battery cell with a safety valve part having a hole penetrating from the front side to the back side of the airtight sheet by pressing the space around the electrode plate group, as shown in FIG. As shown in Fig. 5 (1), two sheets 6 are normally in close contact with each other.
Are separated by the rise in the internal pressure of the battery due to the gas generation, and the silicone oil 13 existing between the two sheets 6 is pushed up [Fig. 5 (2)], and when the gas reaches the lower end of the through hole 9, the gas becomes In this case, since the product of the present invention is the through hole 9, the sheet 6 around the hole is easily opened, and since the through hole 9 part becomes a space, the silicone oil 13 is discharged. The gas does not stay and is easily discharged [Fig. 5 (3)].

On the other hand, in the case of the conventional product 2 shown in FIG. 3, the valve opening as shown in FIG. 6 is performed by the two sheets 6 [Fig. When separated, the silicone oil 13 existing between the two sheets 6 is pushed up [Fig. 6 (2)], and when reaching the lower end of the small hole 4, the gas is discharged in one direction only. However, as shown in FIG. 6 (3), since the small hole 4 exists only in one sheet 6, only one sheet 6 is opened when the gas is discharged. Since the seat 6 is present in the portion facing the nozzle 4, the silicone oil 13 is retained in the small holes 4 as well, gas discharge is suppressed, and as a result, the valve opening pressure becomes high. In addition, the silicone oil 13 accumulated in the small holes 4 easily closes the gas discharge path up to the small holes 4 and closes the valve at a high internal pressure, so that more gas remains in the battery. . In order to verify these phenomena, FIG. 7 shows the measurement results of the valve operating pressure of the manufactured products equivalent to the conventional products 1 and 2 and the product of the present invention. clearly,
The product of the present invention has the lowest valve opening pressure and exhibits excellent characteristics.

Next, FIG. 8 shows the measurement result of the valve opening pressure when the diameter of the small hole 4 of the conventional product 2 is increased. As a result, the valve opening pressure is small
It turned out to be almost independent of the diameter. This means that the valve opening pressure is determined by the pressure when the gas is discharged at the lower end of the small hole 4, and is independent of the size of the small hole 4 diameter. Therefore, even if the diameter of the small holes 4 on only one side is increased, the gas discharge flow rate does not change, and as a result, it is better to increase the number of small holes 4 in order to shorten the discharge time. When the number of small holes 4 is increased, it is conceivable that problems may occur in workability, accuracy of valve opening pressure, and reliability during pressure reduction.

Example An example of the present invention will be described.

As shown in FIG. 1, the electrode plate group 11 is sandwiched between two sheets 6 made of an airtight synthetic resin film having a thickness of 100 μm, and the peripheral joint portion 5 and the two discontinuous portions which are not continuous with the peripheral joint portion 5 are provided. The joint portion 12 is provided by heat welding. At this time the discontinuous joint 12
Has a distance of 5 mm from the peripheral joint 5 and a distance of 10 mm between the two discontinuous joints 12. 2 through holes 9
A through hole having a diameter of 1 mm was provided at a position 3 mm from the peripheral joint 5 in the middle of the two discontinuous joints 12, and silicone oil was applied between the two peripheral sheets to form a safety valve portion.

The lead-acid battery thus produced (hereinafter referred to as the "invention product") and conventional products 1 and 50 were manufactured in a quantity of 50, and the valve-opening pressure and airtightness at a reduced pressure of 0 to -250 mmHg were measured.

The results are shown in Table 1. In addition, valve opening pressure and seat (battery case)
FIG. 9 shows the relationship between the deformation amounts of.

As can be seen from Table 1, the product of the present invention has a valve opening pressure of 13 to 17
It was mmHg, and the airtight leak at the time of depressurization was 0. In contrast, the conventional product 1 had a high valve opening pressure of 63 to 79 mmHg. Conventional product 2
Has a valve opening pressure of 23 to 29 mmHg, which is higher than that of the product of the present invention.
An airtight leak occurred. It is considered that the cause of the airtight leak is due to the deformation of the sheet 6 around the small holes 4 at the time of production as shown in FIG.

In producing the safety valve portion of Conventional Product 2, two methods were considered. One is a method of joining the two sheets 6 and then providing the small holes 4 in only one sheet 6,
A half-cutting method is required to cut off only one of the two thin sheets 6. However, for this purpose, the half-cutting side sheet 6 needs to have a release film as the outermost layer, and the release film must have heat resistance during heat welding. If the sheet 6 is a laminated sheet, the adhesive strength of the laminating agent of the release film needs to be weaker than that of the main body sheet 6. Therefore, in the case of half-cutting, the release film is required, and a step of peeling off the film after cutting is required, which causes a problem in production efficiency. The other one is a method in which a small hole 4 is provided in advance in one sheet 6 by using a drill or a punching jig, and then the other sheet 6 is joined. In this case, there arises a problem that the positions of the small holes 4 are displaced. For example, when the small hole 4 is displaced from the normal position between the discontinuous joints 12 by 1 mm in the direction of a in FIG. Raised. On the contrary, the small holes 4 are oriented in the direction of the peripheral joint portion 9 [3rd
The valve opening pressure increased to 39 mmHg when it was deviated by 1 mm in the direction (b) in Fig. 1). This is because when the small holes 4 are close to the electrode plate group 11, it becomes difficult for the two sheets 6 to come into contact with each other due to the group thickness, and when they are separated, it becomes difficult for the two sheets 6 to come off. Therefore, the position of the small hole 4 influences the valve opening pressure of the safety valve and the airtightness at the time of pressure reduction, and therefore it is necessary to fix the position very accurately.

In addition, regardless of the method of the conventional product 2, when the small hole 4 is provided in the sheet 6, deformation due to burrs and slack is likely to occur, and as a sectional view taken along the line DD ′ of FIG. 4 (1) showing this case. Since a gap is formed between the seats 6 around the small holes 4 as shown in FIG. 4 (2), reliability such as airtight leakage is impaired as a safety valve.

On the other hand, in the product of the present invention, since the through hole 9 may be provided after the two sheets 6 are joined together, the production can be performed accurately and easily.

As described above, the product of the present invention has a lower valve opening pressure of the safety valve than the conventional product, and can be said to be an excellent safety valve in ensuring airtightness during depressurization. In addition, in terms of manufacturing man-hours, the product of the present invention can be performed in the smallest number.

Effects of the Invention As described above, the present invention simply provides a sealed battery with a highly reliable safety valve that satisfies a predetermined (low valve opening pressure) opening pressure level as compared with conventional products, In addition, it is judged that it has high industrial value in terms of production efficiency.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention (product of the present invention) (1).
(2) A main part front view, (2) A main part sectional view taken along the line AA ', and FIG. 2 shows a conventional sealed lead-acid battery (conventional product 1) (1) Main part front view, (2) FIG. 3 is a sectional view of a main part taken along the line BB ′, FIG. 3 is a front view of the main part of a conventional sealed lead-acid battery (conventional product 2), and (2) A view taken along the line CC ′. Partial cross-sectional views, FIG. 4 shows a case where the conventional product 2 is deformed around the small holes (1) A front view of the main parts, (2) A cross-sectional view of the main parts taken along the line D-D ′, Fig. 5 shows (1) Fig. 1A- in normal condition of the product of the present invention.
A sectional view of the valve portion taken along the line A ', (2) A sectional view of the valve portion taken along the line AA' in Fig. 1 in the case where the internal pressure increases due to gas generation,
(3) FIG. 1 is a sectional view of the valve portion taken along the line AA ′ in FIG. 1 at the time of gas discharge, and FIG. 6 is (1) FIG.
Sectional view of the valve section taken along the line C ′, (2) Sectional view of the valve section taken along the line CC ′ of FIG. 3 when the internal pressure increases due to gas generation,
(3) FIG. 3 is a sectional view of the valve portion taken along the line CC ′ of FIG. 3 at the time of discharging gas, FIG. 7 is a curve diagram showing the measurement results of the valve operating pressures of the product of the present invention and the conventional products 1 and 2, and FIG. FIG. 9 is a curve diagram showing the measurement result of the valve opening pressure when the diameter of the small hole is changed in the conventional product 2, and FIG. 9 shows the relationship between the valve opening pressure and the deformation amount of the seat (battery case). It is a curve figure. 1 is an anode plate, 2 is a separator, 3 is a cathode plate, 4 is a small hole,
5 is a peripheral joint, 6 is a sheet, 7 is a non-joint, 8 is a synthetic resin reinforcing material, 9 is a through hole, 10 is a terminal, 11 is an electrode plate group, 12 is a discontinuous joint, 13 is silicone oil .

Front page continuation (72) Inventor Yasuo Wada 2-1-1, Nishishinjuku, Shinjuku-ku, Tokyo Shinshinto Electric Co., Ltd. (72) Inventor Tsutomu Ogata 1-1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Japan Telegraph and Telephone Co., Ltd. Michiko Sakai (56) Reference JP-A 63-174265 (JP, A) ) JP-A-62-272457 (JP, A)

Claims (1)

[Claims] 1. An electrode plate group is arranged between two airtight sheets, and the periphery of the airtight sheet is joined, and the two airtight sheets are discontinuous inside the peripheral joint portion. A sealed battery having a safety valve portion formed in a portion surrounded by the discontinuous joint portion and the peripheral joint portion, wherein the safety valve portion is one of the airtight sheets. A through hole communicating from the outer surface to the outer surface of the other airtight sheet, and having oil between the inner surfaces of the two airtight sheets around the through hole, each of the two airtight sheets The periphery of the through hole is adhered to by the oil, and each through hole is
A sealed battery which is communicated with a portion of the electrode plate group through a gap other than a discontinuous joint on the inner surface of a sheet of airtight sheet.