JP3565580B2 - Battery with explosion-proof safety device and method of manufacturing the same - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a battery provided with an explosion-proof safety device and a method of manufacturing the same, and more particularly, to a technique for a high energy density battery such as a cylindrical lithium ion secondary battery.
[0002]
[Prior art]
Explosion-proof safety devices integrated into a battery include (1) a safety valve, (2) a pressure-sensitive cutoff circuit, and (3) 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 cut-off circuit operates when the pressure in the battery case rises abnormally, cuts off the charging current or the discharging current inside the battery, and prevents the abnormal charging or discharging from continuing. The temperature-sensitive shut-off circuit responds to an abnormal rise in the temperature inside the battery, sharply increases the internal resistance of the battery, reduces the charge current or discharge current, and prevents the abnormal charge or abnormal discharge from continuing.
[0003]
Many of the recent cylindrical lithium-ion rechargeable batteries have a safety valve and one or both of a pressure-sensitive shut-off circuit and a temperature-sensitive shut-off circuit, resulting in an abnormal state such as a short circuit or overcharge. At this time, it is designed such that the cutoff circuit is activated to stop the discharge and the safety valve is 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 and highly productive as possible. It is to make something.
[0004]
A typical structure of a battery provided with a safety valve and a pressure-sensitive shut-off circuit is disclosed in Japanese Patent Application Laid-Open No. 2-288063. This battery is basically composed of a bottomed cylindrical metal battery case, a power generation element housed in the battery case, and a lid element closing the opening of the battery case. Are integrated into the lid element. The lid element includes an external terminal plate having a gas vent hole, an intermediate pressure-sensitive plate made of a thin metal plate that is easily bent and broken, and an insulating plate called a lead stripper. The pressure in the battery case acts on the intermediate pressure-sensitive plate. 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 holes in the external terminal plate. Is done. This is the function of the safety valve. Further, a lead tab connected to one electrode of the power generating element is welded to a central convex portion of the intermediate pressure sensing plate through a small hole at 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 swell outward, but since the position of the lead tab is regulated by the insulating plate, welding between the lead tab and the intermediate pressure-sensitive plate is released, leading to the external terminal plate. The charging or discharging current circuit is interrupted. This is the function of the pressure-sensitive cutoff circuit.
[0005]
[Problems to be solved by the invention]
In the above-mentioned Japanese Patent Application Laid-Open No. 2-288063, the intermediate pressure-sensitive plate and the insulating plate, which are the components of the lid element, are temporarily assembled by an intermediate fitting body to facilitate the ultrasonic welding process of the lead tab and the intermediate pressure-sensitive plate. The precision is improved and the assembly of the lid element and the attachment to the battery case are facilitated. However, mass productivity and assembly accuracy are completely insufficient for the following reasons.
[0006]
First, there is a problem that the process of welding the lead tab to the intermediate pressure sensing plate and then assembling the lid element is extremely troublesome. That is, the lead tab connected to one electrode of the power generation element housed in the battery case is pulled out of the case, the lead tab is welded to the intermediate pressure sensing plate temporarily assembled with the intermediate fitting body, and then the lead tab is used. An external terminal plate is superimposed on the upper surface side of the intermediate pressure-sensitive plate connected to the battery case side, the outer peripheral portion of the intermediate pressure-sensitive plate is caulked and integrated with the external terminal plate, and a sealing gasket is mounted on the outer periphery thereof. . This entire operation is a very difficult process to handle, and it is difficult to improve mass productivity. Also, the work of fitting the central convex portion of the intermediate pressure-sensitive plate into the small hole of the insulating plate and welding the lead tab to the convex portion through the small hole itself is troublesome, and it is difficult to increase the accuracy. Furthermore, after the lead tab is welded to the central convex portion of the intermediate pressure-sensitive plate, the outer peripheral portion of the intermediate pressure-sensitive plate is crimped to integrate the external terminal plate. It also acts on the lead tab welding point, and the welding point may come off. As a result, the welding strength eventually varies, and the operation accuracy and reliability of the pressure-sensitive shut-off circuit decrease.
[0007]
The present invention has been made in view of the above-described conventional problems, and has as its object to improve the operation accuracy and reliability of an explosion-proof safety device and to improve the assemblability and mass productivity of a battery provided with the explosion-proof safety device. is there.
[0008]
[Means for Solving the Problems]
A battery provided with an explosion-proof safety device according to the present invention includes a bottomed cylindrical metal battery case, a power generation element housed in the battery case, and a lid element closing an opening of the battery case. The lid element has an external terminal plate, an intermediate pressure-sensitive plate, an internal terminal plate, an insulating ring, and a sealing gasket, and the external terminal plate and the internal terminal plate are made of a relatively large rigid metal plate. The outer shape is circular, and a gas vent hole is formed in the middle part. The middle pressure-sensitive plate is made of a thin metal plate that is easy to bend and breaks, and a short cylindrical part is continuous around the outer periphery of the disk part. It was manufactured in a shallow cup shape. The insulating ring is disposed in contact with the disk portion from the inner periphery of the cylindrical portion of the intermediate pressure-sensitive plate, the internal terminal plate is fitted into the inner periphery of the insulating ring, and the cylindrical portion of the intermediate pressure-sensitive plate is By being crimped inward, the intermediate pressure-sensitive plate and the internal terminal plate are integrated with an appropriate gap therebetween via the insulating ring, and a central portion of at least one of the intermediate pressure-sensitive plate and the internal terminal plate is provided. The intermediate pressure-sensitive plate, wherein the contact portion is locally welded, and the insulating ring and the internal terminal plate are integrated by the caulking; and The external terminal plate superimposed on the sealing gasket is fitted into the inner periphery of the ring-shaped sealing gasket to constitute the integral lid element. The tip of a lead tab connected to one electrode of the power generating element is welded to the lower surface of the internal terminal plate, and the integral lid element is fitted into the inner periphery of the opening of the battery case, and The opening gasket is compressed inward to compress the sealing gasket, thereby sealing the battery case.
[0009]
In the manufacturing method of the present invention, in manufacturing the battery, the insulating ring and the internal terminal plate are fitted on the inner periphery of the cylindrical portion of the intermediate pressure-sensitive plate, and then the cylindrical portion is swaged. The pressure-sensitive plate and the internal terminal plate are locally welded at the center thereof, and then the intermediate pressure-sensitive plate formed by integrating the insulating ring and the internal terminal plate and the external terminal plate are sealed inside the sealing gasket. The cover is fitted around and forms the integral lid element formed by superimposing the external terminal plate on the intermediate pressure-sensitive plate. Thereafter, the tip of the lead tab is welded to the lower surface of the internal terminal plate.
[0010]
When the function of a temperature-sensitive shut-off circuit is added to the explosion-proof safety device, the intermediate pressure-sensitive plate formed by integrating the insulating ring and the internal terminal plate, and a temperature-sensitive resistance having a positive characteristic formed in a donut plate shape. An element and the external terminal plate are fitted on the inner periphery of the sealing gasket so as to be sequentially overlapped with each other, and the integral lid element is formed by sandwiching the resistance element between the intermediate pressure-sensitive plate and the external terminal plate.
[0011]
[Action]
The pressure in the battery case acts on the intermediate pressure-sensitive plate through the gas vent hole of the internal terminal plate. When the internal pressure rises abnormally, the intermediate pressure-sensitive plate is deformed so as to expand outward, the welding point between the intermediate pressure-sensitive plate and the internal terminal plate is peeled off, and the charge or discharge current circuit connected to the external terminal plate is interrupted (the current pressure is reduced). Pressure cutoff circuit). When the intermediate pressure-sensitive plate is further deformed, it is eventually broken, and the gas in the case is safely released to the outside (safety valve). Further, in the case where the temperature-sensitive resistor is added, when the temperature of the battery abnormally rises, the resistance value of the temperature-sensitive resistor inserted in the charge or discharge current circuit connected to the external terminal plate increases, and the charge, Or, reduce the discharge current (temperature-sensitive shut-off circuit).
[0012]
【Example】
FIG. 1 shows the structure of a battery provided with an explosion-proof safety device (including a temperature-sensitive shut-off circuit) according to an embodiment of the present invention, and FIG. The basic configuration of this battery includes a bottomed cylindrical metal battery case 1, a power generation element 2 housed in the battery case 1, and a lid element that closes an opening of the battery case 1.
[0013]
The lid element has an external terminal plate 3, an intermediate pressure-sensitive plate 4, an internal terminal plate 5, an insulating ring 6, and a sealing gasket 7. The external terminal plate 3 and the internal terminal plate 5 are made of a relatively rigid metal plate, have a circular outer shape, and have a gas vent hole formed in an intermediate portion. The central portion of the external terminal plate 3 is convex upward, and the central portion of the internal terminal plate 5 is slightly convex downward.
[0014]
The intermediate pressure-sensitive plate 4 is made of a thin metal plate that is easily bent and easily broken, and as shown in FIG. 2, is manufactured in a shallow cup shape in which a short cylindrical portion 4b is continuously formed on the outer periphery of a disk portion 4a. The insulating ring 6 is made of a suitable elastic plastic, and is disposed in contact with the disk portion 4a from the inner periphery of the cylindrical portion 4b of the intermediate pressure sensing plate 4, as shown in FIG. The intermediate pressure-sensitive plate 4 and the internal terminal plate 5 are integrated via an insulating ring 6 with an appropriate gap therebetween by crimping the cylindrical portion 4a inward. A small convex portion 4c is formed in the middle pressure-sensitive plate 4 and the central portion, and the lower end of the convex portion 4c contacts the internal terminal plate 5, and the contact portion is locally welded.
[0015]
That is, as shown in FIG. 2A, the insulating ring 6 is fitted on the inner periphery of the cylindrical portion 4b of the intermediate pressure sensing plate 4, and then the inner terminal plate 5 is placed on the inner periphery of the insulating ring 6 as shown in FIG. Then, as shown in FIG. 2 (c), the cylindrical portion 4b is swaged, and then the intermediate pressure-sensitive plate 4 and the internal terminal plate 5 are locally welded (laser, ultrasonic, resistance) at the center thereof. In this welding process, both parts are completely positioned, and the intermediate pressure-sensitive plate 4 is already caulked before welding. Therefore, high-precision welding quality can be easily obtained.
[0016]
Thereafter, as shown in FIG. 1, the intermediate pressure-sensitive plate 4 in which the insulating ring 6 and the internal terminal plate 5 are integrated, the temperature-sensitive resistance element 9 having a positive characteristic formed in a donut plate shape, and the external terminal plate 3 are connected. The sealing gasket 7 is inserted into the inner periphery of the sealing gasket 7 so as to be overlapped in order to form an integral lid element in which the temperature-sensitive resistance element 9 is sandwiched between the intermediate pressure-sensitive plate 4 and the external terminal plate 3. Then, the tip of the lead tab 8 pulled out from the power generation element 2 housed in the battery case 1 is welded to the lower surface of the internal terminal plate 5. Thereafter, the integral lid element is fitted into the inner periphery of the opening of the battery case 1, and the case opening is caulked inward to compress the sealing gasket 7 to seal the case.
[0017]
One electrode of the power generating element 2 is connected to the internal terminal plate 5 by a lead tab 8, and the internal terminal plate 5 is connected to the intermediate pressure-sensitive plate 4 at the central welding point, and the intermediate pressure-sensitive plate 4 is connected via the temperature-sensitive resistance element 9. Connected to the external terminal plate 3. A load circuit is connected to the external terminal plate 3. Then, the pressure in the battery case 1 acts on the intermediate pressure sensing plate 4 through the gas vent hole of the internal terminal plate 5. When the internal pressure rises abnormally, the intermediate pressure-sensitive plate 4 is deformed so as to expand outward, the welding point between the intermediate pressure-sensitive plate 4 and the internal terminal plate 5 is peeled off, and the charge or discharge current circuit connected to the external terminal plate 3 is cut off. (Pressure-sensitive cutoff circuit). When the intermediate pressure-sensitive plate 4 is further deformed, it finally breaks, and the gas in the case 1 is safely released to the outside (safety valve). When the temperature of the battery rises abnormally, the resistance value of the temperature-sensitive resistance element 9 inserted in the charge or discharge current circuit connected to the external terminal plate 3 increases, and the charge or discharge current decreases (temperature-sensitive). Cutoff circuit). If the temperature-sensitive resistance element 9 is eliminated and the external terminal plate 3 is directly stacked on the intermediate pressure-sensitive plate 4, an explosion-proof safety device without a temperature-sensitive shut-off circuit can be obtained.
[0018]
【The invention's effect】
According to the present invention, the lid element incorporating the safety valve and the pressure-sensitive shut-off circuit (and also the temperature-sensitive cut-off circuit) is assembled as an independent component element, and the lead tab is attached to the lid element immediately before mounting the lid element on the battery case. To be welded. Therefore, the whole assembling process becomes very simple, and mass productivity is improved. In addition, the welding of the intermediate pressure sensing plate and the internal terminal plate, which are the main parts of the pressure sensing cutoff circuit, can be performed in an independent state, and the welding is performed after the positioning between the parts is completely performed. Is very simple and therefore the welding accuracy is improved. In addition, since the welding is performed after the intermediate pressure-sensitive plate is caulked, the caulking after the welding as in the related art prevents the welded portion from being peeled off. Further, the insulating ring absorbs mechanical stress even when the battery case is closed and swaged, so that harmful stress is not easily applied to the welding point. As a result, the welding strength is stabilized, and the operation characteristics of the pressure-sensitive cutoff circuit are stabilized.
[Brief description of the drawings]
FIG. 1 is a sectional view of a main part of a battery provided with an explosion-proof safety device according to an embodiment of the present invention.
FIG. 2 is a schematic view showing an assembling process of a main part of the battery.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Battery case 2 Power generation element 3 External terminal plate 4 Intermediate pressure sensing plate 4a Disk portion 4b Cylindrical portion 4c Convex portion 5 Internal terminal plate 6 Insulation ring 7 Sealing gasket 8 Lead tab 9 Temperature sensitive resistance element

Claims (4)

A battery comprising a bottomed cylindrical metal battery case, a power generation element housed in the battery case, and a lid element closing an opening of the battery case,
The lid element has an external terminal plate, an intermediate pressure-sensitive plate, an internal terminal plate, an insulating ring, and a sealing gasket, and the external terminal plate and the internal terminal plate are made of a relatively large rigid metal plate. The outer shape is circular, and a gas vent hole is formed in the middle part. The middle pressure-sensitive plate is made of a thin metal plate that is easy to bend and breaks, and a short cylindrical part is continuous around the outer periphery of the disk part. It was made into a shallow cup type
The insulating ring is disposed in contact with the disk portion from the inner periphery of the cylindrical portion of the intermediate pressure-sensitive plate, the internal terminal plate is fitted into the inner periphery of the insulating ring, and the cylindrical portion of the intermediate pressure-sensitive plate is By being crimped inward, the intermediate pressure-sensitive plate and the internal terminal plate are integrated with an appropriate gap therebetween via the insulating ring, and a central portion of at least one of the intermediate pressure-sensitive plate and the internal terminal plate is provided. The intermediate pressure-sensitive plate, wherein the contact portion is locally welded, and the insulating ring and the internal terminal plate are integrated by the caulking; and The external terminal plate superimposed on is fitted into the inner periphery of the ring-shaped sealing gasket to constitute the integral lid element,
The tip of a lead tab connected to one electrode of the power generating element is welded to the lower surface of the internal terminal plate, and the integral lid element is fitted into the inner periphery of the opening of the battery case, and A battery provided with an explosion-proof safety device, wherein the opening portion is crimped inward to compress the sealing gasket and seal the battery case. 2. The battery according to claim 1, wherein a temperature-sensitive resistance element having a positive characteristic formed in the shape of a donut plate is sandwiched between the intermediate pressure-sensitive plate and the external terminal plate, and the intermediate sense element is inserted through the resistance element. A battery provided with an explosion-proof safety device, wherein a pressure plate and the external terminal plate are electrically connected. In manufacturing the battery according to claim 1, the insulating ring and the internal terminal plate are fitted to the inner periphery of the cylindrical portion of the intermediate pressure-sensitive plate, and then the cylindrical portion is swaged. The internal terminal plate is locally welded at a central portion thereof, and then the intermediate pressure-sensitive plate formed by integrating the insulating ring and the internal terminal plate and the external terminal plate are fitted into the inner periphery of the sealing gasket. A battery comprising: forming the integral lid element by superposing the external terminal plate on the intermediate pressure-sensitive plate; and then welding a tip of the lead tab to a lower surface of the internal terminal plate. Manufacturing method. 4. The manufacturing method according to claim 3, wherein the insulating ring and the internal terminal plate are integrated with each other, the intermediate pressure-sensitive plate, a temperature-sensitive resistance element having a positive characteristic formed in a donut shape, and the external terminal plate. The sealing gasket is inserted into the inner periphery of the sealing gasket so as to be overlapped in order, and the integrated lid element is formed by sandwiching the resistance element between the intermediate pressure sensing plate and the external terminal plate. .

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