JPH08171898A - Rectangular electrochemical element equipped with explosion-proof safety device and its manufacture - Google Patents

Abstract

PURPOSE: To improve safety by providing a pressure sensitive current shut off mechanism in the explosion-proof safety device of a rectangular electrochemical element. CONSTITUTION: A boss portion 1a is formed in the center of a sealing plate 1, and a vent hole 7a is formed in the centers of an internal terminal plate 3 and an external terminal plate 7. Cylindrical portions 5a are continuously set on the periphery of a flexible, breakable, and thin disc portion 5b so as to form a pressure sensitive plate 5. The internal terminal plate 3 and the pressure sensitive plate 5 are successively press-fitted/stacked inside a sealing gasket 2, the sealing gasket 2 is press-fitted into the boss portion 1a of the sealing plate 1, the pressure-sensitive plate 5 and the internal terminal plate 3 are welded at a protrusion 5c. and the tip of a lead tab 12 is welded to the lower face side of the internal terminal plate 3. The external terminal plate 7 is placed on the opening ridge portion of the sealing gasket 2, a retaining plate 9 is welded to the sealing plate 1, and the periphery of the sealing plate 1 and the opening inner periphery of a case 10 is welded so as to seal the case 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a prismatic electrochemical device having an explosion-proof safety device and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, as an explosion-proof safety device integrally incorporated in a prismatic electrochemical element, for example, FIG.
There is an explosion-proof safety device for prismatic batteries shown in (b). In this explosion-proof safety device, a cover plate 21 is fixed to the open end of the prismatic battery case 20, and a rivet-type terminal 25 is fixed to a central opening of the cover plate 21 via a sealing gasket 22. There is. This rivet-type terminal 25 has a lead tab 2
4 is connected to one end thereof and is electrically connected to one electrode of the power generating element 23 connected to the other end of the lead tab 24. Further, the cover plate 21 is formed with a thin gas vent valve 21b in which a groove portion 21a is formed, and the gas vent valve 21b has an abnormal rise in pressure in the case 20 due to misuse such as overcharging or short circuit. At that time, the groove 21a is broken and the gas is safely discharged to the outside to prevent the explosion.

[0003]

However, in the prismatic electrochemical device provided with the explosion-proof safety device of FIGS. 4 (a) and 4 (b) described above, the increase of the internal pressure is suppressed by breaking the groove 21a. However, the current continues to flow through the conductive path from the power generating element 23 to the rivet-shaped terminal 25.
Therefore, it is conceivable that a chemical reaction such as an electrode reaction of the power generation element progresses, the temperature continues to rise accordingly, and finally ignition occurs.

The present invention has been made in view of the above problems, and an object thereof is to provide a prismatic electrochemical device having an explosion-proof safety device with improved safety by providing a pressure-sensitive current interruption mechanism in the explosion-proof safety device of a square electrochemical element. An object is to provide an element and a manufacturing method thereof.

[0005]

In order to achieve the above object, in an electrochemical device provided with an explosion-proof safety device of the present invention, a bottomed rectangular case, an electrochemical element housed in this case, and A rectangular electrochemical element comprising a lid element with a rectangular opening closed, the lid element having a sealing plate, a sealing gasket, an internal terminal plate, a pressure sensitive plate, and an external terminal plate, The sealing plate is a metal plate having a boss portion projecting downward in the center thereof, and the boss portion is continuous with a flange portion extending inward from its projecting end, and the sealing gasket is a cylindrical resin. The inner terminal plate and the outer terminal plate are circular metal plates having a relatively large rigidity with a gas vent hole formed in the center thereof, and the pressure-sensitive plate is a thin circular plate portion that is easily bent and easily broken. The cylindrical part is continuous on the outer circumference, The internal terminal plate, the pressure-sensitive plate, and the external terminal plate are fitted in the boss portion of the sealing plate through the sealing gasket in a state of being sequentially laminated from below, and the cylindrical portion of the pressure-sensitive plate is The upper end surface is pressed against the lower surface of the external terminal plate, and the pressure sensitive plate and the internal terminal plate are brought into contact with each other only at a convex portion formed in the central portion of the pressure sensitive plate and the contact portion is locally closely adhered. By this, the lid element is integrally formed, the tip of the lead tab connected to one electrode of the electrochemical element is connected to the lower surface of the internal terminal plate, and the opening of the case and the sealing plate are airtight. The case is hermetically sealed by being fitted to.

[0006] Preferably, the outer peripheral portion of the pressure sensitive plate is closely fitted and airtightly fitted to the sealing gasket while being press-fitted into the inner peripheral portion of the sealing gasket, and the outer peripheral portion of the sealing gasket is of the sealing plate. The boss portion may be closely fitted and airtightly fitted in the inner peripheral portion of the boss portion, and the outer periphery of the sealing plate and the inner periphery of the opening of the case may be welded and airtightly joined. desirable.

Further, in the manufacturing method of the present invention, in manufacturing a rectangular electrochemical element having an explosion-proof safety device, the internal terminal plate and the pressure-sensitive plate are sequentially press-fitted and laminated inside the sealing gasket. A sealing gasket is press-fitted inside the boss portion of the sealing plate, the pressure sensitive plate and the internal terminal plate are locally welded at the convex portions thereof, and the tip of the lead tab is welded to the lower surface side of the internal terminal plate. Then, the external terminal plate is placed on the opening edge of the sealing gasket, the pressing plate is welded to the sealing plate, and the outer periphery of the sealing plate and the inner periphery of the opening of the case are welded.

[0008]

The pressure in the case acts on the pressure sensitive plate through the gas vent hole of the internal terminal plate. When the internal pressure rises abnormally, the pressure sensitive plate is deformed so as to bulge outward, the contact portion between the pressure sensitive plate and the internal terminal plate is separated, and the current path connecting to the external terminal plate is cut off. When the pressure-sensitive plate is further deformed, the pressure-sensitive plate is finally broken and the gas in the case is safely released to the outside.

[0009]

FIG. 1 shows the structure of an electrochemical device equipped with an explosion-proof safety device (including a pressure-sensitive cutoff mechanism) according to an embodiment of the present invention.
It is shown in a longitudinal sectional view of the main part of (a) and a plan view of (b). The basic configuration of this electrochemical element is composed of a bottomed cylindrical metal electrochemical element case 10, an electrochemical element 11 housed in the case 10, and a lid element that closes the opening of the case 10.

This lid element includes a metal sealing plate 1, a resin sealing gasket 2, a metal internal terminal plate 3, a resin first insulating ring 4, a metal pressure sensitive plate 5, and a metal sealing plate. The cylinder 6 includes a metal external terminal plate 7, a second insulating ring 8 made of resin, and a metal holding plate 9.

The sealing plate 1 has a rectangular outer peripheral shape that substantially matches the shape of the opening of the case 10, and has a boss portion 1a protruding downward in the center thereof. The boss portion 1a has a flange portion 1b extending inwardly from its protruding end.
Are continuous.

The sealing gasket 2 has a cylindrical portion 2a continuous to the outer periphery of a flange portion 2b extending inward. The internal terminal board 3 is a disk having a relatively large rigidity and a plurality of gas vent holes 3a formed in the center thereof.

In the pressure-sensitive plate 5, a cylindrical portion 5a is continuous with the outer periphery of a thin disk portion 5b which is easily bent and easily broken. A small convex portion 5c is formed in the central portion of the disc portion 5b. Further, as shown in the plan views of FIGS. 2A and 2B, the disk portion 5b has a gas discharge groove 5d cut out.

The sealing cylinder 6 is a cylinder having a relatively large rigidity. The external terminal board 7 is a disk having a relatively large rigidity,
The center is convex upward and a gas vent hole 7a is formed. The holding plate 9 has a circular hole 9a formed in the center thereof.

The procedure for assembling the above-described electrochemical device component will be described below.

First, the outer periphery of the sealing cylinder 6 is press-fitted into the inner peripheral portion of the cylindrical portion 5a of the pressure sensitive plate 5. The inner terminal plate 3, the first insulating ring 4 and the pressure sensitive plate 5 are sequentially press-fitted and laminated on the inner peripheral portion of the sealing gasket 2. At this time, the pressure-sensitive plate 5 maintains an appropriate gap with the internal terminal plate 3 via the first insulating ring 4, and the pressure-sensitive plate 5 and the pressure-sensitive plate 5 are brought into contact with each other only at the convex portion 5c and the contact portion is locally adhered. Has been done.

The outer peripheral portion of the thus-assembled sealing gasket 2 is press-fitted into the inner peripheral portion of the boss portion 1a of the sealing plate 1 to be airtightly fitted.

Next, the electrochemical element 11 in which one end of the lead tab is connected to one electrode of the lead tab is inserted into the case 10, and the electrolytic solution is injected.

Next, the pressure sensitive plate 5 and the internal terminal plate 3 are connected to the convex portion 5
Resistance welding is locally performed at c and the tip of the lead tab 12 is resistance welded to the lower surface side of the internal terminal plate 3.

Next, the external terminal plate 7 is placed on the upper end surfaces of the sealing cylinder 6 and the cylindrical portion 5a of the pressure sensitive plate 5, and the holding plate 9 is inserted from its circular hole 9a to the convex central portion of the external terminal plate 7. After mounting on the external terminal board 7 via the second insulating ring 8 at the projecting position, the pressing board 9 and the sealing board 1 are welded to form an integral lid element. At this time, the sealing gasket 2, the pressure sensitive plate 5, and the boss portion 1a of the sealing plate 1 are sandwiched so as to be airtight at their respective contact surfaces.

Then, the outer peripheral edge of the sealing plate 1 and the inner peripheral edge of the opening of the case 10 are laser-welded and airtightly joined to each other, whereby the opening of the case 10 is sealed by the integrated lid element.

The operation of the above-described structure will be described.

One electrode of the electrochemical element 11 is connected to the internal terminal plate 3 by the lead tab 12, the internal terminal plate 3 is connected to the pressure-sensitive plate 5 at the central welding point, and the pressure-sensitive plate 5 is connected to the external terminal at its upper end surface. It is connected to the lower surface of the plate 7. A load circuit is connected to this external terminal board 7. And
The pressure in the case 10 acts on the pressure sensitive plate 5 through the gas vent hole 3 a of the internal terminal plate 3.

When the internal pressure rises abnormally, as shown in FIG.
As shown in (b), the circular plate portion 5b of the pressure sensitive plate 5 is deformed so as to bulge outward, the welding point between the convex portion 5c and the internal terminal plate 3 is peeled off, and the current path connecting to the external terminal plate 7 is cut off. (Pressure-sensitive current interruption mechanism). When the disk portion 5b is further deformed, it finally breaks, and the gas in the case 1 is safely released to the outside (safety valve). That is, the disc portion 5 of the pressure sensitive plate 5
b serves as both a pressure-sensitive current cutoff mechanism and a safety valve.

The materials and dimensions of each of the above-mentioned components are set in consideration of various factors such as desired pressure-sensitive current interruption characteristics, degassing characteristics, strength, and assemblability.

Further, the shape of the gas discharge groove 5d of the pressure sensitive plate 5 is not limited to the shape shown in FIGS. 2 (a) and 2 (b), but may be formed according to a desired breaking characteristic.

Furthermore, the pressure sensitive plate 5 and the sealing cylinder 6 may be integrated by extending the inner peripheral surface of the cylindrical portion 5a of the pressure sensitive plate 5 inward to increase the thickness thereof. in this case,
The assembly process is simplified.

Furthermore, when connecting the pressure-sensitive plate 5 and the internal terminal plate 3, it is sufficient to make contact with the convex portion formed in the central portion of either one of them, and not the disc portion 5b but the internal terminal plate 3 You may provide the convex part which protrudes outward in the center part.

The present invention can be applied to various electrochemical devices such as high energy density batteries such as lithium ion secondary batteries and electric double layer capacitors.

[0030]

According to the present invention, when the internal pressure rises abnormally, the current path from the electrochemical element to the external terminal plate is cut off, so that gas generation due to the flow of current can be prevented and safety is improved.

[Brief description of drawings]

FIG. 1 shows a prismatic electrochemical device provided with an explosion-proof safety device according to an embodiment of the present invention, (a) is a longitudinal sectional view of a main part,
(B) is a plan view.

FIG. 2 is a plan view of a pressure sensitive plate according to an embodiment of the present invention.

FIG. 3 is a longitudinal sectional view of an essential part showing an explosion-proof operation of a rectangular electrochemical device provided with an explosion-proof safety device according to an embodiment of the present invention, (a) showing a state where a current path is cut off, (b). Shows the state of gas release.

FIG. 4 shows a prismatic battery equipped with a conventional explosion-proof safety device,
(A) is a plan view and (b) is a longitudinal cross-sectional view of a main part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Sealing plate 5c Convex part 1a Boss part 5d Gas release groove 1b Flange part 6 Sealing cylinder 2 Sealing gasket 7 External terminal plate 2a Cylindrical part 7a Gas vent hole 2b Flange part 8 Second insulating ring 3 Internal terminal plate 9 Holding plate 3a Gas vent hole 9a Circular hole 4 First insulating ring 10 Electrochemical element case 5 Pressure sensitive plate 11 Electrochemical element 5a Cylindrical part 12 Lead tab 5
b Disk part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuhiro Nakamura 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Inventor Kazuo Takada 5-36-11 Shinbashi, Minato-ku, Tokyo Fuji Electrochemical Co., Ltd.

Claims (3)

[Claims] 1. A bottomed rectangular case 10 and this case 1
A rectangular electrochemical element comprising an electrochemical element 11 housed in 0 and a lid element that closes a rectangular opening of the case 10, the lid element including a sealing plate 1 and a sealing gasket 2.
The inner terminal plate 3, the pressure sensitive plate 5, and the outer terminal plate 7, and the sealing plate 1 has a boss portion 1a protruding downward in the center thereof.
The boss portion 1a is a metal plate formed with a continuous flange portion 1b extending inward from its protruding end, the sealing gasket 2 is a cylindrical resin, and the inner terminal plate 3 and the external The terminal plate 7 is a circular metal plate having a relatively large rigidity in which gas vent holes 3a and 7a are formed in the center thereof, and the pressure sensitive plate 5 is a cylinder around the outer circumference of a thin disk portion 5b which is easily bent and easily broken. The portion 5a is continuous, and the inner terminal plate 3, the pressure sensitive plate 5, and the outer terminal plate 7 are sequentially laminated from below, and the boss portion of the sealing plate 1 is inserted through the sealing gasket 2. It is fitted inside, the upper end surface of the cylindrical portion 5a of the pressure sensitive plate 5 is pressed against the lower surface of the external terminal plate 7, and is formed in the central portion of at least one of the pressure sensitive plate 5 and the internal terminal plate 3. Both contact only at the convex portion 5c, and the contact portion is locally adhered. By this, the lid element is integrally formed, the tip of the lead tab 12 connected to one electrode of the electrochemical element 11 is connected to the lower surface of the internal terminal plate 3, and the opening of the case 10 and the sealing A prismatic electrochemical element provided with an explosion-proof safety device, characterized in that the case 10 is sealed by hermetically fitting with the plate 1. 2. The sealing gasket 2 with the outer peripheral portion of the pressure sensitive plate 5 being press-fitted into the inner peripheral portion of the sealing gasket 2.
And the outer peripheral portion of the sealing gasket 2 is press-fitted into the inner peripheral portion of the boss portion 1a of the sealing plate 1 so that the outer peripheral portion of the sealing gasket 2 is tightly fitted to the boss portion 1a. The prismatic electrochemical device with an explosion-proof safety device according to claim 1, wherein the outer periphery of the sealing plate 1 and the inner periphery of the opening of the case 10 are welded and airtightly joined. 3. In manufacturing a prismatic electrochemical device equipped with the explosion-proof safety device according to claim 1, the internal terminal plate 3 and the pressure sensitive plate 5 are provided inside the sealing gasket 2.
Then, the sealing gasket 2 assembled in this manner is press-fitted into the boss portion 1a of the sealing plate 1, and the pressure sensitive plate 5 and the internal terminal plate 3 are projected into the convex portion 5c.
And the tip of the lead tab 12 is welded to the lower surface side of the internal terminal board 3 to locally weld the external terminal board 7
Is placed on the opening edge of the sealing gasket 2, the pressing plate 9 is welded to the sealing plate 1, and the outer periphery of the sealing plate 1 and the inner periphery of the opening of the case 10 are welded. Of manufacturing a square electrochemical device with an explosion-proof safety device.