JPH11224658A - Current cut-off element and battery having current cut-off element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve operation accuracy and reliability of an explosion-proof safety mechanism and apply the mechanism to a rectangular battery. SOLUTION: A metal outside terminal 4, a metal combining ring 5, a pressure-sensitive rupture member 6, and a metal inside terminal 11 that has received an insulating spring 10 in its inside are stacked sequentially. The pressure-sensitive rupture member 6 is composed by superposing a diaphragm 7 having a pressure receiving part 7a protruded and a metal disc 9 having a small thickness part 9b formed interposing an insulating plate 8, and connecting electrically the disc 9 and the pressure receiving part 7a of the diaphragm 7 which come in contact with each other by means of welding. A current cut-off element 3 is formed by storing and fixing the composite member formed as above in a metal terminal case 14 through a gasket 13. Then, the current cut-off element 3 is welded to a sealing lid of a case. When the internal pressure of the case rises to a predetermined value, the small thickness part 9b of the disc 9 is ruptured by the deformation due to the swell of the diaphragm 9 and the preload on the disc 9 by the spring 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery explosion-proof safety mechanism for interrupting a current due to a rise in pressure in a battery.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing an explosion-proof mechanism for a cylindrical battery disclosed in Japanese Patent Application Laid-Open No. 9-7573.

This battery includes a cylindrical metal battery case 21 having a bottom, a power generating element (not shown) housed in the battery case 21, a lead tab 22 connected to one electrode of the power generating element, and A cover element for closing the opening of the battery case 21 electrically connected to the lead tab 22 is provided.

The lid element includes a metal terminal plate 23, an intermediate pressure-sensitive plate 25 made of a flexible metal plate, an insulating fixed plate 26, an upwardly projecting projection 27a and a base 27.
b and an insulating tubular gasket 2
8 is provided. The terminal plate 23 and the fixed plate 26 are formed with gas vent holes 23a and 26a, respectively, and the intermediate pressure-sensitive plate 25 is formed with a thin portion 25a so as to break at a predetermined internal pressure.

[0005] One electrode of the power generating element is connected to a conductive member 27 by a lead tab 22, and the conductive member 27 is connected to the intermediate pressure sensing plate 25 by welding at a welding point 27c on the upper surface of the projection 27a. The pressure plate 25 is connected to the terminal plate 23 via the temperature-sensitive resistance element 24.

In the cylindrical battery having the above structure, when gas is generated inside the battery due to overdischarge, overvoltage, or the like, the gas pressure in the battery case 21 is applied to the intermediate pressure sensitive plate 25 through the gas vent hole 26a of the fixed plate 26. Works. When the internal pressure rises abnormally, the intermediate pressure-sensitive plate 25 is deformed so as to expand outward, the welding at the welding point 27c of the conductive member 27 is peeled off, and the charge or discharge current path leading to the terminal plate 23 is cut off. The thin portion 25a of the pressure plate 25 breaks and gas is released from the gas vent hole 23a of the terminal plate 23.

[0007]

By the way, there are few prismatic batteries equipped with a current cut-off mechanism as seen in the above-mentioned cylindrical battery. Usually, a part of the battery case is damaged and the internal pressure is reduced. It was used as an explosion-proof measure by destroying the thin part when ascending.

[0008] The reason why it is difficult to equip the prismatic battery with the current interrupting mechanism is as follows due to the dimensional and structural restrictions due to the shape of the battery itself as follows.

That is, since the rectangular battery has a rectangular shape, the deformation of the outer case 21 with respect to the increase in the internal pressure is larger than that of the above-mentioned cylindrical battery, and the current cutoff mechanism operates without rupturing the outer case 21. To do so, the operating pressure must be set extremely low.

If the current interrupting mechanism of the cylindrical battery described above is used as a rectangular battery (for example, 11 mm long and 34 mm wide)
When applied to a half-inch size small rectangular battery having a bottom of
The area of 5 must be smaller than that of the cylindrical battery. In order to significantly deform the intermediate pressure-sensitive plate 25 with a small pressure-receiving area, it is necessary to make the plate thickness extremely thin,
By reducing the thickness, the weldability between the conductive member 27 for obtaining electrical contact and the intermediate pressure-sensitive plate 25 deteriorates. Further, after the current is cut off, the current path that has been cut off may re-contact due to some external impact or the like.

Furthermore, in the current interrupting mechanism inherent in the cylindrical battery, the welding strength at the welding point 27c is affected by the weldability of the welding point 27c and the variation in the diameter of the welding nugget. It was difficult to do.

The present invention has been made in view of the above-mentioned drawbacks of the conventional explosion-proof mechanism, and can reliably cut off the current path when the internal pressure of the battery reaches a predetermined pressure value. It is an object of the present invention to provide a current interrupting element with high operational accuracy and high reliability that can reliably prevent re-contact, and a battery having the current interrupting element.

[0013]

That is, in the present invention,
A diaphragm (7) composed of a metal outer terminal (4) having a pressure transfer hole (4a) for venting, a metal connection ring (5), and a metal plate having a pressure receiving portion (7a) protruding at the center. ) And a metal disk (9) having a pressure transmitting hole (9a) and a thin-walled portion (9b) formed in place are overlapped with a ring-shaped insulating plate (8) interposed therebetween, and the disks (9) that come into phase contact with each other And a pressure-sensitive rupture member (6) formed by electrically connecting the pressure-receiving portion (7a) of the diaphragm (7) to the pressure-receiving portion (7a) of the diaphragm (7), and a spring for preloading the welded portion of the disk (9) from the back side. (10) and a metal inner terminal (11) having a pressure transmitting hole (11a) and having the spring (10) contracted inside thereof in order, and superimposing these superposed members on an insulating gasket (13). ) To the metal terminal case (14) While paying, and constitutes a current cut-off device (3) is integrally secured polymerization member of caulking the interior openings of the terminal casing (14) on the inside.

Further, in the present invention, a cylindrical outer case (1) having a bottom, a power generating element housed in the outer case (1), and a lead tab (2) connected to one electrode of the power generating element. And attached to the opening of the outer case (1),
A battery is composed of the lead tab (2) and the current interrupting element (3) electrically connected.

In the battery constructed as described above, when the pressure in the outer case (1) rises to a predetermined value, the diaphragm (7) constituting the pressure-sensitive rupture member (6) swells, and this swelling occurs. Of the disk (9) by the displacement of the disk (9) by the spring and the preload on the disk (9) by the spring (10) acting to assist this.
b) is broken and the conductive path between the lead tab (2) and the outer terminal (4) is cut off.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing a main configuration of a prismatic battery equipped with an explosion-proof safety mechanism according to the present invention.
(A) is a plan view, (b) is a front sectional view, and (c) is a side sectional view.

The prismatic battery of the present invention has a metal outer case 1 (for example, a half-inch size-compatible square case having a bottom of 11 mm in length and 34 mm in width) having a bottomed rectangular cylindrical shape. A power generation element (not shown) composed of a positive electrode and a negative electrode is accommodated in 1.

A sealing lid 15 for sealing is laser-welded to the opening of the outer case 1, and a current interrupting element 3 as an explosion-proof safety mechanism according to the present invention is provided at the center of the sealing lid 15. It is mounted by welding as indicated by 16 in the figure. A thin metal lead tab 2 led from one electrode (for example, a positive electrode) of the power generating element is connected to the bottom of the current interrupting element 3 by welding.

FIG. 2 is a sectional view showing the internal structure of the current interrupting element 3. As shown in FIG. The current interrupting element 3 is a combination of a cylindrical metal outer terminal 4 (for example, a positive electrode terminal) having a pressure transmitting hole 4a for degassing in a proper position, a metal connecting ring 5, and a plurality of members described later. Pressure-sensitive rupture member 6 constituted by
And a metal spring 10 that has been subjected to insulation treatment, a cylindrical metal inner terminal 11 having a pressure transmission hole 11 a in place similarly to the outer terminal 4, and a metal reinforcing ring,
These members are sequentially laminated so that their peripheral portions are overlapped, and this polymer is housed in the same bowl-shaped metal terminal case 14 via a bowl-shaped insulating gasket 13.

The pressure-sensitive breaking member 6 is formed by laminating a diaphragm 7 and a disk 9 via a ring-shaped insulating plate 8. The diaphragm 7 is formed of a flexible thin metal plate, and has a truncated cone-shaped pressure receiving portion 7 at the center.
a is protrudingly provided. The disk 9 is a metal disk, and as shown in FIG. 4 (a), an elongated pressure transmitting hole 9a which surrounds a peripheral edge portion which comes into contact with the top surface of the pressure receiving portion 7a of the diaphragm 7 at the time of superposition. Are annularly connected in a row, and between the pressure transmission holes 9a and 9a is shown in FIG.
A thin wedge-shaped cut 9b having a predetermined shearing strength corresponding to a set current interruption pressure value is provided as shown in FIG.
It has been.

Next, the procedure for assembling the current interrupting element 3 will be described with reference to FIG. In this figure, the members for assembling are shown in a direction corresponding to the assembling work, and are turned upside down with respect to the current interrupting element 3 shown in FIGS.

At the time of assembly, first, the diaphragm 7, the insulating plate 8, and the disk 9 are overlapped to assemble the pressure-sensitive breaking member 6. At this time, the thin portion 9b of the disk 9 is superimposed on the pressure receiving portion 7a of the diaphragm 7 so as to be opposed, and the top surface of the contacting pressure receiving portion 7a and the disk 9 are electrically connected by welding.

Next, the gasket 13 is inserted through the opening of the terminal case 14, and the reduced diameter portions 13a, 14a of both members are fitted so as to overlap each other, and the inner wall of the terminal case 14 is covered with the insulating gasket 13. .

Next, the outer terminal 4 is inserted into the gasket 13, and its head 4 b is attached to the reduced diameter portion 1 of the terminal case 14.
4a, and the exposed portion is used as a load connection terminal (for example, a positive terminal).

Further, the connecting ring 5 is superimposed on the flange 4c of the outer terminal 4, the pressure-sensitive rupture member 6 is superimposed so that the diaphragm 7 is in contact with the connecting ring 5, and then the spring 1 is mounted on the cylinder.
In this case, the inner terminal 11 is overlapped with the inner terminal 11 (in this case, the spring 10 is pressed against the surface of the disk 9). Finally, the reinforcing ring 12 is overlapped on the flange portion of the inner terminal 11. After each member is housed, the opening side of the terminal case 14 is curled inward to integrally fix the interior overlapping member, and the assembly of the current interrupting element 3 is completed.

After welding the assembled current interrupting element 3 to the sealing lid 15, the head 11 of the inner terminal 11 of the current interrupting element 3
b, the lead tab 2 is connected by welding, and the sealing lid 15 is welded to the opening of the outer case 1 to seal the outer case 1.

Next, the operation of the explosion-proof safety mechanism by the current interrupting element 3 will be described with reference to FIGS.

In the cylindrical battery having the above-described structure, one of the electrodes (the positive electrode in the present embodiment) in the power generating element passes through the lead tab 2 led out therefrom and passes through the inner terminal 11, the disk 9, and the diaphragm. 7. Conduction is made to the outer terminal 4 by a current path formed by the connection ring 5.

When gas is generated inside the battery for some reason such as overcharging or overdischarging, the internal pressure of the battery gradually increases, and the pressure is increased by the pressure transmitting hole 11a of the inner terminal 11 and the pressure transmitting hole of the disk 9. Acts on the diaphragm 7 through 9a. Due to this gas pressure, the diaphragm 7 receives a force that tends to deform upward (toward the outer terminal 4 side) in the figure, and attempts to displace the disk 9 welded thereto upward. The disk 9 is pre-pressed upward from below by a spring 10. The internal pressure rises abnormally and the force of the diaphragm 7 pulling the disk 9 and the pre-load by the spring 10 combine to form a thin portion 9a of the disk 9. If the shear strength becomes higher, the thin portion 9a of the disk 9
And the current path (that is, the discharge current path or the charging current path) is completely interrupted. Since the spring 10 is insulated, it does not itself contribute to conduction between the inner terminal 11 and the disk 9.

As described above, in the present embodiment, the disk 9
Since the current path connecting the power generating element and the outer terminal 4 is cut off by breaking the thin portion 9a of the above, welding between the pressure receiving portion 7a of the diaphragm 7 and the disk 9 for obtaining electrical contact is a certain degree or more. It is not necessary to strictly control the accuracy of the welding strength. Therefore, even if the weldability and the weld nugget diameter vary to some extent, this does not directly affect the setting of the current cutoff pressure value (that is, the operating pressure of the explosion-proof safety mechanism).

Further, by prestressing the disk 9 in the gas pressure direction using the spring 10, even if the structure in which the pressure receiving area of the diaphragm 7 cannot be made large like the small rectangular battery shown in the present embodiment, it is low. The current can be interrupted by pressure, and the preload by the spring 10 acts in a direction to assist the deformation of the diaphragm 7 even after the disk 9 is broken. The inconvenience that the connection is made can be prevented.

As described above, the current interrupting pressure value can be adjusted by appropriately changing the spring strength regardless of the thickness of the thin portion 9b of the disk 9.

In this embodiment, the prismatic battery has been described. However, the shape is not limited to this, and it is of course applicable to a cylindrical battery.

FIG. 6 shows an embodiment of the present invention. In the case of a cylindrical battery, the terminal case 14 constituting the current interrupting element 3 can be replaced by beading of the outer case 1.

[0035]

As described above, according to the present invention,
When the current is interrupted, the thin portion of the disk is pre-pressed by the spring, so that the current can be interrupted at a low pressure even if the pressure receiving area of the diaphragm is small.

Further, the preload by the spring acts to assist the deformation of the diaphragm even after the disk is broken, and the current path once broken is electrically reconnected for some reason. Because of the prevention, the reliability of the current interruption mechanism is improved, and the safety of the battery is improved.

Further, since the breaking point of the current path is provided on a disk whose shear strength can be relatively easily controlled,
It is not affected by variations in welding to obtain electrical contact, variations in the diameter of the welding nugget, and the like, and a stable current interruption pressure can be always maintained, so that the operation accuracy of the explosion-proof safety mechanism is improved.

Further, in the present invention, the current interrupting element is applied not only to a cylindrical battery but also to a rectangular battery which cannot structurally increase the pressure receiving area of the diaphragm, thereby providing a prismatic type having an explosion-proof safety mechanism having a current interrupting function. The battery can be realized and has a remarkable effect on improving the reliability.

[Brief description of the drawings]

FIG. 1 is a diagram showing a main configuration of a prismatic battery equipped with an explosion-proof safety mechanism according to the present invention, wherein (a) is a plan view, (b) is a front sectional view, and (c) is a side sectional view.

FIG. 2 is a cross-sectional view showing the internal structure of the current interrupting device according to the present invention.

FIG. 3 is a cross-sectional view of the current interrupting element in a state where the explosion-proof safety mechanism according to the present invention has been activated.

FIG. 4 is a view showing a structure of a disk according to the present invention;
(A) is a plan view and (b) is a cross-sectional view.

FIG. 5 is a view showing a procedure for assembling the current interrupting element according to the present invention.

FIG. 6 is a cross-sectional view showing a main configuration of a cylindrical battery provided with an explosion-proof safety mechanism according to the present invention.

FIG. 7 is a sectional view of a main part of a cylindrical battery equipped with a conventional explosion-proof safety mechanism.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Outer case 2 Lead tab 3 Current cutoff element 4 Outer terminal 4a Pressure transmitting hole 5 Connecting ring 6 Pressure sensitive breaking member 7 Diaphragm 7a Pressure receiving part 8 Insulating plate 9 Disk 9a Pressure transmitting hole 9b Thin part 10 Spring 11 Inner terminal 11a Pressure transmitting hole 12 Reinforcing ring 13 Gasket  14 Terminal case

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Minoru Inagaki 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Inventor Hikaru Osuka 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Inside Electrochemical Co., Ltd.

Claims (2)

[Claims] 1. A metal plate having a metal outer terminal (4) having a pressure transmitting hole (4a) for degassing, a metal connecting ring (5), and a pressure receiving portion (7a) protruding at the center. A diaphragm (7) made of a metal and a metal disk (9) having a pressure transmitting hole (9a) and a thin portion (9b) formed in place are superimposed on each other with a ring-shaped insulating plate (8) interposed therebetween to make phase contact. A pressure-sensitive rupture member (6) formed by electrically connecting the disk (9) and a pressure receiving portion (7a) of the diaphragm (7) by welding; It has a spring (10) for preloading and a pressure transmitting hole (11a), and the spring (1) is provided inside.
0) is overlapped with a metal inner terminal (11) in order, and these superposed members are housed in a metal terminal case (14) via an insulating gasket (13). A current interrupting element, wherein an opening of a terminal case (14) is caulked inward to integrally fix the superposed member of the interior. 2. An outer case (1) having a bottomed cylindrical shape, a power generating element housed in the outer case (1), a lead tab (2) connected to one electrode of the power generating element, and the outer case. A battery comprising a current interrupting element (3) according to claim 1, which is mounted in an opening of a case (1) and electrically connected to the lead tab (2).