JPH0877995A - Battery with explosion-proof safety device - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the operating accuracy and reliability of the explosion-proof safety device, and to improve the assemblability and mass productivity of batteries equipped with the explosion-proof safety device. [Structure] Metal caulking ring 1 with diaphragm 8
0, a temperature-sensitive resistance element ring 7 is superposed, and a lower washer 6, an insulating ring 5, a metal ring 4 with a movable piece, an upper washer 3, and a metal terminal 2 are sequentially superposed on the thermosensitive resistive element ring 7 and have a circular outer shape. The parts are stacked concentrically. All of these are fitted into the inner circumference of the ring-shaped sealing gasket 11 to form an integral lid element. The metal terminal 2 has a hat shape,
A gas vent hole 2a is formed. Metal ring with movable piece 4
In the center of the ring portion 4a, a cantilever strip-shaped movable piece 4b is integrally formed. The ring portion 4a does not contact the lower washer 6 below the insulating ring 5. The tip portion of the movable piece 4b is sandwiched between the lower washer 6 and the insulating ring 5 and comes into pressure contact with the lower washer 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery provided with an explosion-proof safety device, and more particularly to a technique for a battery having a high energy density such as a cylindrical lithium ion secondary battery.

[0002]

2. Description of the Related Art Explosion-proof safety devices integrated into a battery include a safety valve, a pressure-sensitive cutoff circuit, and a temperature-sensitive cutoff circuit. The safety valve operates when the pressure inside the battery case rises abnormally, and safely releases the gas inside the battery to the outside to prevent an explosion. The pressure-sensitive shutoff circuit operates when the pressure inside the battery case rises abnormally, shuts off the charging current or the discharging current inside the battery, and prevents the abnormal charging or the abnormal discharge from continuing. The temperature-sensitive cutoff circuit is responsive to an abnormal temperature rise in the battery, rapidly increases the internal resistance of the battery and throttles the charging or discharging current to prevent the abnormal charging or discharging from continuing.

Many of the recent cylindrical lithium ion secondary batteries are equipped with a safety valve and also with one or both of a pressure-sensitive cutoff circuit and a temperature-sensitive cutoff circuit, so that an abnormal state such as a short circuit or overcharge occurs. When it becomes, the shutoff circuit is activated to stop charging or discharging and the safety valve is also activated. What is extremely important in designing this type of battery is to realize a highly accurate and reliable explosion-proof safety device with a structure that is as compact as possible and highly mass-producible, and as a supplementary auxiliary function of the battery. To make the safety device very inexpensive.

A typical structure of a battery provided with a safety valve and a pressure-sensitive cutoff circuit is shown in Japanese Patent Laid-Open No. 288063.
This battery is basically composed of a bottomed cylindrical metal battery case, a power generating element housed in the battery case, and a lid element that closes the opening of the battery case.The safety valve and the pressure-sensitive cutoff circuit are covered by a lid. It is integrated into the element. The lid element includes an external terminal plate having a vent hole, an intermediate pressure sensitive plate made of a thin metal plate that is easily bent and easily broken, and a lead stripper. The pressure inside the battery case acts on the intermediate pressure-sensitive plate, and when the pressure increases, the intermediate pressure-sensitive plate bends outward, and when the pressure exceeds the set pressure, the intermediate pressure-sensitive plate breaks and gas is safely released from the gas vent hole of the external terminal. It This is the function of the safety valve. A lead plate connected to one electrode of the power generating element is welded to a central convex portion of the intermediate pressure sensitive plate through a small hole in the center of the insulating plate. When the internal pressure of the battery rises abnormally, the intermediate pressure sensitive plate is deformed so as to bulge outward. Since the position of the lead plate is regulated by the insulating plate, the welding between the lead plate and the intermediate pressure sensitive plate is released, and the charge or discharge current circuit connected to the external terminal is cut off. This is the function of the pressure-sensitive cutoff circuit.

[0005]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
In Japanese Patent No. 88063, an intermediate pressure-sensitive plate (safety valve), which is a component of a lid element, and an insulating plate are provisionally assembled by an intermediate fitting body to facilitate the ultrasonic welding process of the lead plate and the intermediate pressure-sensitive plate. It is designed to be more accurate and to facilitate the assembly of the lid element and its attachment to the battery case. However, it is completely insufficient in terms of mass productivity and assembly accuracy for the following reasons.

First, there is a problem that the process of welding the lead plate to the intermediate pressure sensitive plate and then assembling the lid element is extremely troublesome. That is, the lead plate connected to one electrode of the power generating element housed in the battery case is pulled out of the case, the lead plate and the intermediate pressure-sensitive plate temporarily assembled by the intermediate fitting body are welded together, and then, Overlay the external terminal plate on the upper surface of the intermediate pressure-sensitive plate connected to the power generation element with the lead plate, crimp the outer peripheral part of the intermediate pressure-sensitive plate to integrate it with the external terminal plate, and then attach the sealing gasket to these outer peripheries. become. This entire work is a very difficult process to handle, and it is difficult to improve mass productivity. Also,
The work itself of fitting the central convex portion of the intermediate pressure-sensitive plate into the small hole of the insulating plate and welding the lead plate to the convex portion through the small hole itself is troublesome, and it is difficult to improve accuracy. Furthermore, after welding the lead plate to the central convex portion of the intermediate pressure-sensitive plate, the outer peripheral portion of the intermediate pressure-sensitive plate is caulked to integrate the external terminal board.However, the mechanical stress in this caulking process is caused by the intermediate pressure-sensitive plate. It also acts on the lead plate welding point of, and the welding point may peel off. As a result, the welding strength eventually fluctuates, and the operating accuracy and reliability of the pressure-sensitive cutoff circuit deteriorate.

The present invention has been made in view of the above-mentioned conventional problems, and an object thereof is to improve the operation accuracy and reliability of the explosion-proof safety device, and to improve the assemblability and mass productivity of a battery equipped with the explosion-proof safety device. To raise.

[0008]

A battery provided with an explosion-proof safety device of the present invention comprises a cylindrical metal battery case having a bottom, a power generating element housed in the battery case, and an opening of the battery case. It consists of a sealing lid element. The lid element is
A circular metal terminal having a gas vent hole, a circular diaphragm at least the surface of which is insulative, and a metal caulking ring sandwiching the outer peripheral edge portion of this diaphragm from above and below,
A metal ring with a movable piece integrally having a movable piece in a cantilever state in the center of the ring portion, an insulating ring, and a ring-shaped sealing gasket, and the insulating ring on the metal caulking ring with the diaphragm. Are stacked, the metal ring with the movable piece is stacked on the insulating ring, the metal terminal is stacked on the metal ring with the movable piece, and the whole of them is fitted into the inner circumference of the sealing gasket to be integrated. And a ring portion of the metal ring with a movable piece contacts the insulating ring and does not contact the metal caulking ring, and a tip portion of the movable piece does not contact the metal caulking ring. It is connected. The tip of the lead plate connected to one electrode of the power generating element is welded to the lower surface of the metal caulking ring, and the integral lid element is fitted into the inner periphery of the opening of the battery case, The sealing gasket is compressed by crimping the opening portion of the inside, and the battery case is sealed.

Here, the tip of the movable piece may be sandwiched between the metal caulking ring and the insulating ring so as to be pressed against the metal caulking ring.
In this case, the insulating ring is made of a thermoplastic or heat-shrinkable material, and when the temperature rises, the clamping force of the movable piece sandwiched between the metal caulking ring and the insulating ring is reduced. It is desirable to configure

If necessary, another metal ring may be sandwiched between the metal terminal and the metal ring with a movable piece. Further, when the function of the temperature-sensitive cutoff circuit is added to the explosion-proof safety device, a positive temperature-sensitive resistor element ring and a second element are provided between the metal caulking ring and the insulating ring.
Only the metal ring or the temperature-sensitive resistance element ring is sandwiched, and the metal caulking ring is electrically connected to the movable piece via the temperature-sensitive resistance element ring or the second metal ring.

[0011]

The pressure in the battery case acts on the diaphragm, and when the pressure rises abnormally, the diaphragm deforms so as to bulge outward, and abuts on the movable piece arranged immediately above and pushes it up. When the movable piece is strongly pushed up, the tip of the movable piece connected to the metal crimp ring is disengaged, and the electrical connection between the tip and the metal crimp ring is broken. As a result, the charge / discharge path connected to the metal terminal is cut off (pressure-sensitive cutoff circuit). When the diaphragm is deformed further, it finally breaks and the gas in the case is safely released to the outside (safety valve). Further, in the case where the temperature sensitive resistance element ring is added, when the temperature of the battery abnormally rises, the resistance value of the temperature sensitive resistance element inserted in the charge / discharge path connected to the metal terminal increases, and the charge / discharge current is increased. Decrease (temperature-sensitive cutoff circuit).

[0012]

1 to 4 show the structure of a battery provided with an explosion-proof safety device (including a temperature-sensitive cutoff circuit) according to an embodiment of the present invention. The basic configuration of this battery includes a cylindrical metal battery case 1 having a bottom, a power generation element (not shown) housed in the battery case 1, and a lid element for sealing the opening of the battery case 1.

The lid element includes a metal terminal 2, an upper washer 3 corresponding to the other metal ring, and a metal ring 4 with a movable piece.
An insulating ring 5, a lower washer 6 corresponding to the second metal ring, a temperature-sensitive resistance element ring 7, and a diaphragm 8
A sealing sheet 9, a metal caulking ring 10, and a sealing gasket 11. The plan shapes of some of the components are shown in FIG.

The diaphragm 8 is circular and is made of a sheet material in which both surfaces of a metal sheet are laminated with an insulating film or an insulating sheet material. The outer peripheral edge of the diaphragm 8 is sandwiched between the metal caulking rings 10 from above and below. A seal sheet 9 is sandwiched between the metal caulking ring 10 and the diaphragm 8 to enhance the sealing performance between them.

A temperature sensitive resistance element ring 7 is laid on a metal caulking ring 10 having a diaphragm 8, a lower washer 6 is laid on it, an insulating ring 5 is laid on it, and a movable piece is attached on it. A metal ring 4 is stacked, an upper washer 3 is stacked on the metal ring 4, a metal terminal 2 is stacked on the metal ring 4, and parts having these circular outer shapes are stacked concentrically. These are ring-shaped sealing gaskets 1
It is fitted to the inner circumference of the unit 1 to form an integral lid element. The metal terminal 2 has a hat shape and is formed with a gas vent hole 2a.

As shown in FIG. 4, the metal ring with movable piece 4 is integrally formed with a strip-shaped movable piece 4b in a cantilever state at the center of the ring portion 4a. The movable piece 4b is sufficiently flexible. The metal ring 4 with a movable piece is superposed on the insulating ring 5, and the ring portion 4 a thereof is not in contact with the lower washer 6 below the insulating ring 5. However, the tip of the movable piece 4b is sandwiched between the lower washer 6 and the insulating ring 5 and is in pressure contact with the lower washer 6. Metal ring with movable piece 4
Is electrically connected to the lower washer 6 only at the tip portion of the movable piece 4b. The upper washer 3 is in contact with the ring portion 4a of the metal ring 4 with a movable piece, and the metal terminal 2 is in contact therewith. Metal caulking ring 10
→ The temperature sensitive resistance element ring 7 → the lower washer 6 → the tip of the movable piece 4b → the ring portion 4a → the upper washer 3 → the electrical path of the metal terminal 2 is formed.

After the lid element is integrated with the sealing gasket 11 as described above, the tip of the lead plate 12 connected to one electrode of the power generating element (not shown) is welded to the lower surface of the metal caulking ring 10. . Then, the integral lid element is fitted into the inner periphery of the opening of the battery case 1, and the opening of the battery case 1 is caulked inward to seal the gasket 11.
And the battery case 1 is sealed.

As shown in FIG. 2, the pressure in the battery case 1 acts on the diaphragm 8, and when the pressure rises abnormally, the diaphragm 8 is deformed so as to bulge outward, and the movable piece 4b arranged immediately above is deformed. Abut and push it up. When the movable piece 4b is strongly pushed up, the tip of the movable piece 4b sandwiched between the lower washer 6 and the insulating ring 5 comes off, and the electrical connection between the tip and the lower washer 6 is cut off.
As a result, the electric path connecting the metal terminal 2 and the lead plate 12 is cut off (pressure-sensitive cutoff circuit). When the diaphragm 8 is further deformed, it is finally broken and the gas in the case 1 is safely discharged to the outside (safety valve). When the battery temperature rises abnormally, the resistance value of the temperature-sensitive resistance element ring 7 increases, and the charging current or discharging current is decreased (temperature-sensitive cutoff circuit).

By the way, the insulating ring 5 is made of a polymer material such as thermoplastic or heat-shrinkable plastic, rubber or natural resin, which softens or contracts when the temperature of the battery rises. 5
The holding force of the movable piece 4b sandwiched between the lower washer 6 and the lower washer 6 is appropriately reduced. The easiness of detachment of the movable piece 4b at this portion, the easiness of bending of the diaphragm 8, the hole size of the metal caulking ring 10 or the lower washer 6,
The distance between the diaphragm 8 and the movable piece 4b is appropriately set, and the pressure-sensitive cutoff circuit is designed to operate at an appropriate point (operating pressure and temperature) when the internal pressure of the battery increases due to temperature increase.

The tip of the movable piece 4b is attached to the lower washer 6
The configuration for connection to the (or metal caulking ring 10) side is not limited to the above embodiment, and various means such as adhesion, soldering, ultrasonic welding, spot welding, etc. can be adopted.

[0021]

According to the present invention, the lid element incorporating the safety valve and the pressure-sensitive cutoff circuit (and also the temperature-sensitive cutoff circuit) is assembled as an independent component element, and immediately before the lid element is mounted in the battery case. The lead plate is welded to the lid element. Therefore, the whole assembling process becomes very simple and mass productivity is improved. Further, since the lid element is constructed by a very simple structure in which parts having a circular outer shape are laminated on the inner circumference of the ring-shaped sealing gasket, the assembly thereof is also very simple. Furthermore, since the structure is simple and there are no unstable elements, the operating characteristics of the safety valve and the pressure-sensitive cutoff circuit are stable, and the reliability is improved. Also, the space occupied by the explosion-proof safety device is small, and the proportion of reducing the effective space of the battery is small.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts of a battery including an explosion-proof safety device according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of essential parts in a state in which a safety device for a battery of the same as above is in operation.

FIG. 3 is an enlarged view of a main part of the same battery.

FIG. 4 is a plan view of constituent parts of a lid element in the same battery.

[Explanation of symbols]

 1 Battery Case 2 Metal Terminal 2a Gas Vent Hole 3 Upper Washer (Another Metal Ring) 4 Metal Ring with Movable Piece 4a Ring Part 4b Movable Piece 5 Insulation Ring 6 Lower Washer (Second Metal Ring) 7 Thermosensitive Element Ring 8 Diaphragm 9 Seal sheet 10 Metal caulking ring 11 Sealing gasket 12 Lead plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshiro Harada 5-311, Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (72) Inventor Masakazu Kitakata 5-13-11, Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd.

Claims (6)

[Claims] 1. A battery comprising a bottomed cylindrical metal battery case, a power generation element housed in the battery case, and a lid element for sealing an opening of the battery case, wherein the lid element is , A circular metal terminal having a vent hole, and a circular diaphragm having an insulating surface at least
It has a metal caulking ring that sandwiches the outer peripheral edge of this diaphragm from above and below, a metal ring with a movable piece that integrally has a cantilevered movable piece in the center of the ring part, an insulating ring, and a ring-shaped sealing gasket. , The insulating ring is stacked on the metal caulking ring with the diaphragm, the metal ring with a movable piece is stacked on the insulating ring, and the metal terminal is stacked on the metal ring with a movable piece. , The whole is fitted into the inner circumference of the sealing gasket to form the integral lid element, and the ring portion of the metal ring with a movable piece comes into contact with the insulating ring and the metal caulking ring. No, the tip of the movable piece is connected to the metal caulking ring, and is connected to one electrode of the power generating element. The leading end of the lead plate is welded to the lower surface of the metal caulking ring, the integral lid element is fitted into the inner periphery of the opening of the battery case, and the opening of the battery case is caulked inward. A battery equipped with an explosion-proof safety device, wherein a sealing gasket is compressed and the battery case is sealed. 2. The battery according to claim 1, wherein a tip portion of the movable piece is sandwiched between the metal caulking ring and the insulating ring and is in pressure contact with the metal caulking ring. Batteries with explosion-proof safety device. 3. The battery according to claim 2, wherein the insulating ring is made of a thermoplastic or heat-shrinkable material, and is sandwiched between the metal caulking ring and the insulating ring at a high temperature. A battery provided with an explosion-proof safety device characterized in that the gripping force of the movable piece is reduced. 4. The battery according to claim 1, 2, or 3, wherein another metal ring is sandwiched between the metal terminal and the metal ring with a movable piece. Batteries equipped with the characteristic explosion-proof safety device. 5. The battery according to claim 1, 2, 3, or 4, wherein a temperature sensitive resistance element ring having a positive characteristic is provided between the metal caulking ring and the insulating ring. A battery provided with an explosion-proof safety device, wherein the metal caulking ring is sandwiched and electrically connected to the movable piece via the temperature-sensitive resistance element ring. 6. The battery according to claim 1, claim 2, claim 3, claim 4, or claim 5, wherein the temperature sensing having a positive characteristic is provided between the metal caulking ring and the insulating ring. A resistance element ring and a second metal ring are sandwiched, and the metal caulking ring is electrically connected to the movable piece through the temperature sensitive resistance element ring and the second metal ring. Batteries with explosion-proof safety device.