JPH01319249A - Sealed type cell - Google Patents

Abstract

PURPOSE:To prevent the breakage of the equipment using a sealed type cell by forming a projection protruded outward on the bottom wall of a call case, providing a through hole releasing the internal gas of a cell on the side wall portion of the projection, and forming the through hole smaller than a gas blowout area. CONSTITUTION:When the internal pressure of a cell 4 becomes the preset value or above, a recess section 15a is reversed, notch lines formed on the outer periphery of the recess section 15a are ruptured to form a gas blowout area. The gas blown out through the gas blowout area flows to a free space surrounded by the inner wall of a projection 10 then is released to the outside of the cell little by little via a through hole 13 provided on a side wall portion 12. When the internal gas is released, the reaction force of the released gas is fed to the center direction of the cell, thus no large force is applied in the longitudinal direction of the cell. The cell is prevented from jumping out from the equipment. The through hole 13 is formed smaller than the gas blowout area, thus little content of the cell is released when the internal gas blows out.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is characterized by an explosion-proof plate having a concave portion projecting toward the inside of the battery case fixed to the inside of the bottom wall of the battery case, thereby reducing the internal pressure of the battery. The present invention relates to a sealed battery in which, when the pressure exceeds a predetermined value, the recess is reversed and the scored lines formed on the outer periphery of the recess are broken to form a gas blowout area to reduce the pressure inside the battery.

In the above-mentioned sealed battery, gas is generated inside the battery due to application of overvoltage or short circuit, and the internal pressure of the battery becomes abnormally high, which may destroy the battery case. In order to prevent this, battery cases of sealed batteries have conventionally been provided with an explosion-proof structure.

As such an explosion-proof structure, Japanese Patent Application Laid-Open No. 61-203348
The explanation will be based on the aerosol can shown in FIG. 6. A truncated conical recess 22 is formed in the center of the bottom wall 21 a of the aerosol can 21 and is integrally formed with the aerosol can 21 and protrudes inward from the aerosol can 21 . This recessed portion 22 is formed by a side wall portion 22a and a top portion 22b.
An arcuate notch line 23 is formed in a part of the boundary between the two parts. This scored line 23 forms a blowout area 24 that can be broken and separated. Then, when the pressure inside the aerosol can 21 reaches a predetermined pressure, the ζ side wall portion 22a is warped in the opposite direction, and then the scored line 23 is broken, as shown in FIG. After this, as shown in FIG.
is completely opened and internal gas etc. are released to the outside.

, 0 <"' to do i" However, when the above conventional explosion-proof structure is applied to a sealed battery, when the internal gas is released, the top portion 22b is notched '1tiA.
It rotates around the part where 17 is not formed until it becomes substantially perpendicular to the bottom wall 2ta. As a result, parts of devices that use sealed batteries may be damaged. Further, since the internal gas flows out in the vertically downward direction, a reaction force is generated in the vertically upward direction.

Therefore, the battery may fly out of the battery holder due to the gas release reaction force, and the device may be damaged.

Furthermore, since the blowout area 24 is large, a large amount of not only internal gas but also the contents of the battery is released, which poses a problem such as the risk of damaging the device.

In addition, Special Publication No. 60-200456, Utility Model Publication No. 58-1
Explosion-proof structures have also been proposed in Japanese Utility Model Publication No. 7332, Japanese Utility Model Publication No. 58-26460, and Japanese Utility Model Publication No. 62-25885, but they have the same problems as above.

Therefore, the present invention was made in consideration of the above-mentioned problems, and an object of the present invention is to provide a sealed battery that can dramatically improve performance by preventing damage to equipment in which the sealed battery is used. It is something.

Means of the Invention In order to achieve the above-mentioned object, the present invention includes an explosion-proof plate having a recessed portion protruding toward the inside of the battery case, which is formed on the bottom wall of the battery case so as to protect the inside of the battery. When the pressure exceeds a predetermined value, the recess is reversed and the scored line formed on a part of the outer periphery of the recess is broken, forming a gas blowout area and releasing the internal gas of the battery to the outside. In a sealed battery, a convex portion protruding toward the outside of the battery case is formed at a position facing the concave portion on the outside of the bottom wall of the battery case, and a side wall portion 2 of the convex portion is provided with a convex portion of the battery when the internal gas is released. It is characterized in that a plurality of through holes are provided for releasing internal gas, and the through holes are formed to be smaller than the gas blowing area.

With the above configuration, when the internal pressure of the battery exceeds a predetermined value, the recess is reversed and the scored line formed on the outer periphery of the recess is broken, creating a gas blowout area. is formed. Then, the gas blown out from the gas blowing region flows into a free space surrounded by the inner wall of the convex portion, and then is discharged to the outside of the battery in equal amounts from a plurality of through holes provided in the side wall portion.

At this time, the reaction forces of the released gases mutually move toward the center of the battery, so that little force is applied in the longitudinal direction of the battery. Therefore, it is possible to prevent the battery from flying out from the device.

In addition, since the through hole is formed smaller than the gas blowing area, the contents of the battery are only slightly released when internal gas is released.

Furthermore, when the internal gas is released, the recess rotates slightly around the area where the score line is not formed, and then part of it hits the inner wall of the convex part and does not rotate any further, so that the recess rotates slightly in the longitudinal direction of the battery. The length of the line does not increase.

In addition, since the explosion-proof plate is not exposed, it is possible to prevent the explosion-proof plate from being damaged.

Disaster - Joichi ■ The first embodiment of the present invention is based on FIGS. 1 to 5.
This will be explained below.

As shown in FIG. 1, an electrode group 4 consisting of a positive electrode 1, a negative electrode 2, and a separator 3 is housed in a stainless steel battery case 5. Further, a disk-shaped metal lid 6 is fixed to the opening edge of the battery case 5 by laser welding, thereby sealing the inside of the battery. An insulating backing 7 is inserted through the center of the metal lid 6, and a shaft portion of a terminal 8 fixed with a washer 9 is inserted into the insertion hole of the insulating backing 7.

On the other hand, a convex projection 14 is formed on the bottom wall of the battery case 5, and a stainless steel explosion-proof plate 15 is ring-welded to the projection 14. The explosion-proof plate 15 includes a recessed portion 15a that is formed to protrude under the battery's own power and functions similarly to a disc spring, and this recessed portion 1.
5a and a flange 15b provided on the outer periphery of the flange 5a, and a score line 17 is formed at a part of the boundary between the recessed part 15a and the flange 15b, as shown in FIG. The deformation pressure of the recessed portion 15a is set to approximately 20 to 30 kgf/-, and when this set pressure is reached, the recessed portion 15a is reversed and the scored line 17 is break. This forms a gas blowing region 18 that blows out the internal gas of the battery. Furthermore, a truncated conical protrusion 10 is provided on the bottom wall of the battery case 5 and is integrally formed with the metal case 5 and protrudes outward from the battery. This convex portion 10 is composed of a side wall portion 12 and a top portion 11, and the side wall portion 12 has the above-mentioned scored line 1 as shown in FIG.
Through-holes 13 are formed through which internal gas is released when 7 is broken. These through holes 13 are formed to be smaller than the gas blowing area.

With the above configuration, when the internal pressure of the battery exceeds a predetermined value and a gas blowout area is formed, the gas blown out from this gas blowout area flows into the free space formed by the inner wall of the convex portion 10. After that, equal amounts are discharged to the outside of the battery through two through holes 13 provided in the side wall portion 12.

(Experiment 1) Here, a sealed battery with a conventional structure (the above-mentioned Japanese Patent Application Laid-open No. 61-20
The distance traveled by the battery when internal gas was released was investigated for the sealed battery of the present invention (having a pressure relief device having the structure shown in No. 3348) and the sealed battery of the present invention, and the results are shown in Table 1 below.

As for the test conditions, both batteries were placed on a hot plate heated to about 300° C. and stood still in a horizontal state, and the distance traveled by the batteries before and after internal gas was released was measured. The battery model used was CR173353E (diameter: 17 mm - height: 33.5 mm), and five samples were used each.

Table 1 As shown in Table 1 above, conventional sealed batteries have an average travel distance of 23 CIm (maximum 38cm5 minimum 19cm
), whereas in the sealed battery of the present invention, the moving distance is 4 C1l (maximum 8 cm, minimum 1 cai) on average, and it is recognized that the moving distance is much smaller than the conventional one. This is considered to be due to the following reasons.

That is, when the internal gas flows out from the through holes 13, 13 when internal gas is released, the internal gas (arrow A in Figure 3) is divided to the left and right, so the reaction force of the internal gas outflow (arrow A in Figure 3) Symbol B) is caused by the fact that the reaction force is concentrated at the center of the battery and does not act much in the longitudinal direction of the battery.

(Experiment 2) Next, the weights of the battery contents discharged when internal gas was released from the conventional sealed battery and the sealed battery of the present invention were investigated, and the results are shown in Table 2 below.

The test conditions were 24V direct application (constant voltage charging). In addition, the same battery type as in Experiment 1 was used, and five samples were used each.

Note to Table 2, the discharge weight is the weight of the solid material (eg, positive electrode active material).

As shown in Table 2 above, conventional sealed batteries have an average discharge weight of 2.1g (i large 3.7g, fi small 1.2g)
On the other hand, in the sealed battery of the present invention, the average discharge weight is 0.8 g (i size 1.4 g, minimum 0.2 g), which is significantly reduced compared to the conventional battery. It is recognized that This is the through hole 13 that releases the internal gas of the battery.
- This is because the diameter of the explosion-proof plate 15 is smaller than the fracture diameter of the explosion-proof plate 15.

(Experiment 3) In a sealed battery with a conventional structure and a sealed battery of the present invention,
The amount of change in shape of the battery in the longitudinal direction when internal gas was released was investigated, and the results are shown in Table 3 below.

The test conditions and battery type were the same as in the first experimental example. In addition, three samples were used each.

[Margin below]

Table 3 As shown in Table 3 above, the amount of shape change in the conventional sealed battery is 4.1° on average, whereas the amount of shape change in the sealed battery of the present invention is 0° on average. 2 am, and it is recognized that the amount of shape change is significantly reduced compared to the conventional one. This is because when the internal gas is released, the recessed part 15a of the explosion-proof plate 15 rotates slightly around the part where the notch line 17 is not formed, and then a part of it comes into contact with the inner wall of the convex part 10. This is due to not moving.

In the above embodiment, the battery case 5 and the protrusion 10 are integrally formed, but the structure is not limited to this. For example, as shown in FIG. 5, the battery case 5 and the protrusion 10 are integrally formed. Of course, it is also possible to have a structure in which these are formed separately and welded together after the battery is completed.

Although the explosion-proof plate 15 is made of ordinary stainless steel material, it should be made easier to set the operating pressure (preferably 5US3
It is desirable to use a low-carbon flexible stainless steel material such as 04L, 5US3L6L, or 5US317L.

Further, the fixing of the explosion-proof plate 15 is not limited to ring welding (the same effect can be achieved by laser welding as well. In this case, it is not necessary to form the projection 14).

In addition, the number of through holes 13 is not limited to two, and may be three or more. In this case, the gas release pressure per hole is reduced, so the above effect can be achieved. It is possible to show off your eyebrows.

[As described above, in the case of the sealed battery of the present invention, when internal gas is released, the reaction force of the released gas is directed toward the center of the battery, so an excess force is applied in the longitudinal direction of the battery. Never,
Therefore, it is possible to prevent the battery from flying out from the device.

Further, since the through hole is formed smaller than the gas blowing area, the contents of the battery are only slightly released when the internal gas is blown out.

Furthermore, when the internal gas is ejected, the recess rotates slightly around the area where the score line is not formed, and then a part of it hits the inner wall of the convex part and does not rotate any further, so the longitudinal direction of the battery The length in the direction does not increase.

In addition, since the explosion-proof plate is not exposed, it is possible to prevent the explosion-proof plate from being damaged.

For these reasons, it is possible to prevent damage to equipment, etc. in which the sealed battery is used, and the performance of the sealed battery can be dramatically improved.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing the internal structure of the sealed battery of the present invention;
Fig. 2 is an explanatory diagram showing the flow of internal gas when internal gas is ejected, Fig. 3 is an explanatory diagram showing the reaction force of the emitted gas when internal gas is released, Fig. 4 is an enlarged sectional view of the explosion-proof plate, and Fig. 5 The figure is a sectional view showing another embodiment, FIG. 6 is a partial sectional view showing a conventional pressure relief device, and FIGS. 7 and 8 are explanatory diagrams showing the operating state of the conventional pressure relief device. 5...Battery case, 10...Convex portion, 12...Side wall portion, 13...Through hole, 15...Explosion proof plate, 15a...
・Concave part, 17...notch line. Patent applicant: Sanyo Electric Co., Ltd.

Claims (1)

[Claims] (1) An explosion-proof plate is formed on the bottom wall of the battery case, and has a recess that protrudes toward the inside of the battery case. In a sealed battery in which a scored line formed on a part of the outer periphery of the battery case is broken to form a gas blowout area to release the internal gas of the battery to the outside, A convex portion protruding toward the outside of the battery case is formed at the position, and a plurality of through holes are provided in the side wall portion of the convex portion through which the internal gas of the battery is discharged when the internal gas is discharged, and the through holes are used as the gas outlet. A sealed battery characterized by being smaller than the area.