JPH1186821A - Sealed-type battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an sealed-type battery with a structure to cut off a current- carrying circuit by abnormal increase in the inner pressure of the battery under an abnormal use of the battery. SOLUTION: At a center position of a seal cover bottom plate 6 arranged at an inner side of a battery of a seal cover plate 1, a lower current contact 5 is fixed and also pressurizing opening 6a is formed. At a center portion of a thin metal sheet 2 adjacent to the seal cover bottom plate 6, a convex part 2a is formed, and at a center position thereof an upper current contact 4 fitted is fixed attachable and detachable to/from the lower current contact 5. When an internal pressure is increased abnormally, the pressurizing opening 6a is broken and infiltrating battery internal pressure turns over the convex part 2a of the thin metal sheet 2 to separate the upper current contact 4 from the lower current contact 5. A current-carrying circuit is cut off by the separation of the upper current contact 4 and the lower current contact 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for processing an excessive internal pressure and shutting off an energizing circuit when a sealed battery, particularly a sealed battery having a high energy density, such as a lithium secondary battery, is abnormally used. The present invention relates to a sealed battery provided with a sealing plate structure that can be used.

[0002]

2. Description of the Related Art A sealed battery having a high energy density, such as a lithium secondary battery, generates abnormal gas inside the battery when a device or a charger using the battery fails or is improperly used. The internal pressure may rise abnormally.
A gas venting mechanism is provided for discharging the gas that has occurred abnormally in preparation for such abnormal use. In addition, since the non-aqueous electrolyte secondary battery involves an abnormal temperature rise, an energizing circuit interrupting structure for interrupting the energizing circuit prior to gas discharge is provided.

[0003] As a prior art of a sealed battery provided with the above-mentioned energizing circuit interruption structure, there are Japanese Patent Application Laid-Open Nos. Hei 5-335501, Hei 5-34043, Hei 8-306351, Hei 8-315798, Hei 9 JP-A-129195, JP-A-9-199105, and JP-A-9-199106 are known. The configurations disclosed in these documents are intended to peel off a welded portion between a metal plate deformed due to an abnormal increase in battery internal pressure and a member connected to a power generating element, or to form a thin-walled easily breakable metal plate under pressure deformation. The power supply circuit from the power generation element to the metal cap of the sealing plate is cut off.

[0004]

However, the peel strength of a portion joined by welding is affected by the welding strength and the strength of the members of the welded portion, and the breaking strength at which an easily breakable portion is broken is determined by the thickness of the thin portion. Since precision is required, it is difficult to control peeling or breaking strength to a constant precision, and there has been a problem that it is not possible to maintain a constant precision of interrupting an energizing circuit due to an increase in battery internal pressure. Further, when laser welding is used to limit the welding point to a minute portion, a minute hole may be generated, and the electrolyte may leak from the inside of the battery.

An object of the present invention is to provide a sealed battery in which an energizing circuit interrupting structure for interrupting an energizing circuit when the internal pressure of a battery abnormally rises is configured to operate accurately with respect to the internal pressure of the battery. .

[0006]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention is directed to a metal cap for forming an electrode portion of a sealing plate, wherein an end opening of a battery case accommodating a power generating element is hermetically sealed by a sealing plate. In a sealed battery having a structure in which a thin metal plate provided closer to the inside of the battery is deformed due to an increase in battery internal pressure, a current-carrying circuit from the power generation element to the metal cap is shut off, the sealing plate faces the inside of the battery. A sealing plate bottom plate to which a lower current contact electrically connected to the power generating element is fixed at a central position thereof; and a metal cap provided on the outside of the battery adjacent to the sealing plate bottom plate and electrically connected to the metal cap. A metal part having a bulging part gently bulging in the direction toward the inside of the battery formed at the center thereof, and an upper current contact removably fitted and connected to the lower current contact at the center thereof. Characterized by comprising a plate.

[0007] According to the above configuration, the lower current contact connected to the power generating element and the upper current contact fixed to the thin metal plate are electrically connected by the detachable fitting connection between the two. An energization circuit extending from the metal cap to the metal cap is formed. When the sealed battery provided with the sealing plate configured as described above is abnormally used and the battery internal pressure rises abnormally, the metal sheet is pressurized by the battery internal pressure, and the pressurized metal sheet is compressed by the bulging portion. The upper current contact fixed at the center position of the bulging portion is disengaged from the fitting by applying a pressure higher than the fitting strength at which the lower current contact is fitted, so that the bulging direction of the bulging portion is reversed. Reverse with contacts. The reversing operation of the bulge breaks the fitting connection between the upper current contact and the lower current contact, so that the current-carrying circuit from the lower current contact to the metal cap is interrupted, and becomes a source of an abnormal rise in battery internal pressure. The abnormal current flow was interrupted.

[0008] The sealing plate bottom plate in the above structure is formed so as to block the ventilation between the inside of the battery and the inside of the sealing plate, and breaks open when the pressure due to the battery internal pressure exceeds a predetermined value. It is possible to form a pressurized opening for ventilating between the inside and the inside of the sealing plate. With this configuration, the inside of the sealing plate and the inside of the battery are normally shielded, so that the electrolyte and the volatile components inside the battery do not enter the sealing plate, and the Corrosion and contamination of the components due to the components can be prevented. Since there is a fitting connection portion between the upper current contact and the lower current contact inside the sealing plate, these contaminations are not preferable in terms of electric conduction. Is prevented. In addition, this shielding structure allows the use of a material member that is susceptible to corrosion and contamination due to the components of the electrolyte, so that it is possible to widen the range of selection of components, and it is possible to use a more preferable material for each component. A member can be configured. Further, since the pressure opening is formed, when the internal pressure of the battery becomes equal to or higher than a predetermined value, the pressure opening is broken, the internal pressure of the battery reaches the metal sheet, and the upper portion is formed by the reversing operation of the bulging portion. It is possible to perform an interrupting operation of an energizing circuit that disconnects the fitting connection between the current contact and the lower current contact.

Further, the sealing plate bottom plate is formed by resin molding, and a thin-walled portion can be configured as a pressure opening. Since the bottom plate is an insulator, when a lower current contact is attached, the lower current contact is separately provided by an insulator. It is easy to insulate the contacts from other parts, and also as an insulating gasket that wraps the peripheral part to wrap the peripheral part of each member that constitutes the sealing plate, insulates it from the battery case, and hermetically seals it. Can also be used.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention.

FIG. 1 shows the structure of a sealing plate portion of a sealed battery according to an embodiment of the present invention as a sectional structure. The sealed battery has a bottomed cylindrical shape in which a power generation element is accommodated in a lower part (not shown). The upper opening of the battery case 10 formed in the above is sealed with a sealing plate 1. The sealing plate 1 includes a sealing plate bottom plate 6 to which a lower current contact 5 is fixed via a disk 7 at a center position from the inside of the battery and a central portion formed by bulging the center toward the inside of the battery. A thin metal plate 2 to which an upper current contact 4 removably fitted to a contact 5 is fixed, a PTC 3 which is a ring-shaped critical temperature resistor, and a metal cap 8 having a vent 8a are arranged in this order. The outer peripheral portion is laminated, and the laminated portion is insulated from the battery case 10 by the peripheral portion of the sealing plate bottom plate 6 and fixed to the battery case 10 by caulking. Since the lead 9 connected to the power generating element is joined to the disk 7, an energizing circuit is formed from the disk 7 to the lower current contact 5, the upper current contact 4, the thin metal plate 2, the PTC 3, and the metal cap 8. .

The metal sheet 2 is fixed by lamination around a disk shape as shown in the figure, and a bulging portion 2a which gently bulges toward the inside of the battery is formed at the center, and the bulging portion 2a is formed. The upper current contact 4 is fixed at a center position, and an easily breakable portion 2b is formed in a C shape in the middle of the bulging portion 2a. When this metal thin plate 2 is shown as a specific configuration example, an aluminum plate having a thickness of 0.15 mm is formed with a diameter of 12.7.
mm, and the bulging portion 2a has a C of 5.0 mm in diameter.
Forming a C-shaped thin part using the stamp of the mold shape,
This is referred to as an easily breakable portion 2b, and the upper current contact 4 is fixed to an opening provided at the center position of the bulging portion 2a.

Further, the sealing plate bottom plate 6 is formed by resin molding, and the lower current contact 5 is fixed together with the disk 7 in an opening formed at the center position, and is provided at one or a plurality of positions as shown in the figure. A thin-walled pressure opening 6a is formed.

The connection structure between the upper current contact 4 and the lower current contact 5 is formed as a detachable fitting structure as shown in FIG. As shown in an enlarged view in FIG.
The current circuit from the power generation element to the metal cap 8 is electrically connected by fitting the fitting portion 4a formed on the upper current contact 4 into the loosening portion 5a formed on the head of the lower current contact 5, It is formed by this energization connection.

Also, PTC (Positive Tem)
The property coefficient 3 is a well-known critical temperature resistor and has a negligible electric resistance value in a normal state. However, the temperature is raised to a predetermined temperature range (critical level) due to a rise in temperature caused by the flow of an excessive current. temperature)
Is a positive temperature coefficient resistance element in which the electric resistance value sharply increases when the resistance value exceeds.

The sealed battery provided with the sealing plate 1 having the above-described structure is caused by a gas or the like generated when a device using the sealed battery fails, or is improperly used or abnormally used, such as an external short circuit. An abnormal response operation corresponding to an abnormal increase in the internal pressure or an abnormal temperature increase will be described below with reference to FIGS.

As a case of abnormal use of a battery, a short circuit between the positive and negative electrodes due to a failure of a device using the battery, an overcharge due to a failure of the charger, an overload use ignoring the battery capacity, a positive or negative due to a deliberate or unexpected situation. Short-circuiting between the electrodes, over-discharging due to multiple series connection, reverse charging, and the like can be considered. In order to cope with such abnormal use, three types of abnormal response operations are performed.

First, in the first abnormal response operation, when an excessive current flows, the PTC 3 reaches a critical temperature in a short time due to the excessive current flowing, and its electric resistance increases. Is greatly reduced and the battery is prevented from being damaged due to external short circuit or misuse due to excessive current.

However, in the case of a lithium secondary battery, which is an example of a sealed battery, the PTC 3 is not charged when uncontrolled overcharge or reverse charge due to a failure of a charger or overdischarge in a large number of series connections. Even when the current does not reach the critical temperature, the internal pressure of the battery may increase beyond the safe capacity of the battery. That is, when such an abnormal current continues to flow, the battery temperature rises sharply while decomposing the electrolytic solution and the active material, and generates a large amount of gas or vapor. Therefore, when the battery internal pressure rises above a predetermined pressure, a second abnormality handling operation for interrupting the current supply circuit is started.

The state of each component of the sealing plate 1 shown in FIG. 1 is a normal state, and the internal pressure in the battery case 10 exceeds the breaking strength of the pressure opening 6 a formed in the sealing plate bottom plate 6. In this case, the pressurizing opening 6a formed thinly is broken open, and the internal pressure of the battery that has entered the sealing plate 1 from the opened pressurizing opening 6a is applied to the metal thin plate 2. Swelling portion 2 of metal sheet 2
a is pressed in a direction in which the swelling direction is reversed to the outside of the battery, and when the strength of the upper current contact 4 at the center thereof and the lower current contact 5 exceeds the fitting strength, the swelling portion 2a Invert as shown in FIG. By the reversing operation of the bulging portion 2a, the upper current contact 4 comes out of the lower current contact 5, and the fitting between them is released. The separation of the upper current contact 4 from the lower current contact 5 cuts off the energizing current circuit, so that the abnormal current causing the rise in the battery internal pressure is cut off, and the root of the battery internal pressure rise is eliminated.

However, even if the abnormal current is interrupted, the temperature does not instantaneously decrease, the generation of gas or steam does not subside instantaneously, and if the internal pressure of the battery continues to increase, the third
The abnormal response operation starts. That is, when a large amount of gas or vapor is generated and the internal pressure of the battery reaches a predetermined value set based on the breaking strength of the easily breakable portion 2b provided on the bulging portion 2a of the thin metal plate 2, the easily breakable portion 2b breaks. As a result, the central portion of the thin metal plate 2 is cleaved, and the gas or vapor filling the inside of the battery is discharged from the vent 8a of the metal cap 8 to the outside.

In the above configuration, the sealing plate bottom plate 6 is formed by resin molding and is also used to insulate between the sealing plate 1 and the battery case 10.
A configuration similar to that described above can be configured as shown in FIG.

In the structure of the sealing plate 1a shown in FIG. 4, a structure in which the lower electrode plate 11 made of metal such as aluminum, the gasket 13 and the insulating plate 12 perform the same operation as the sealing plate bottom plate 6 is employed. . A lower current contact 5 is fixed at a center position of the lower electrode plate 11, and a pressure opening 11a is formed which forms a thin portion by engraving and breaks from the thin portion when the battery internal pressure exceeds a predetermined value. I have. Since the lower electrode plate 11 is made of metal, the lower electrode plate 11 is insulated and laminated with the thin metal plate 2 by the insulating plate 12, and the laminated portion is insulated by the gasket 13 and caulked and fixed to the battery case 10.
When the lower electrode plate 11 is formed of an insulator,
It is not necessary to provide the insulating plate 12.

In the structure of the sealing plate 1 or 1a,
Since the energizing circuit is cut off by a detachable fitting structure between the upper current contact 4 and the lower current contact 5, by controlling this fitting strength to be constant, the current-carrying circuit connection by welding used in the prior art is performed. It is possible to eliminate the difficulty in controlling the accuracy of the welding strength and the breaking strength of the easily breakable portion.
Further, the configuration according to the present embodiment has remarkable features not realized in the related art.

That is, as shown in FIGS. 1 and 4, between the inside of the battery and the inside of the sealing plate 1 at normal times, the sealing plate bottom plate 6 is provided.
Alternatively, since it is configured to be completely shielded by the lower electrode plate 11, the fitting side of the thin metal plate 2, the upper current contact 4, and the lower current contact 5 formed of a metal material may have an electrolyte solution inside the battery or the like. It is not exposed to volatile components. It is natural that the members formed of these metal materials use materials which are not corroded by the electrolytic solution or deteriorated by contamination in the prior art, but it cannot be said that there is no change with time. In this configuration, the energization circuit is connected by the fitting contact structure, so it is necessary to shield the inside of the battery particularly to prevent connection failure due to contamination of the fitting contact portion. This has been achieved. Due to the shielding structure between the inside of the battery and the inside of the sealing plate 1, the range of choice of the constituent materials of the members is widened, and the temporal change in the breaking strength accuracy due to corrosion or contamination of the thin-walled portion to be broken at the time of abnormality. Etc. can also be prevented.

In the above embodiment, a cylindrical battery has been described, but a prismatic battery or a battery similar thereto may be similarly configured.

[0027]

As described above, according to the present invention, when the internal pressure of the battery rises abnormally due to abnormal use of the battery, the fitting between the upper current contact and the lower current contact is released and the current connection is cut off. Therefore, the current supply circuit of the excessive current, which has been the root of the abnormal increase of the battery internal pressure, is cut off. Since the interruption of this energizing circuit is performed by releasing the fitting connection between the upper current contact and the lower current contact, the accuracy of the interruption operation due to the internal pressure of the battery can be made constant. Also, since the inside of the battery and the inside of the sealing plate are shielded by the sealing plate bottom plate, not only can the contamination of the upper and lower current contacts due to the components of the electrolyte be prevented, but also the effects of corrosion and contamination by the electrolyte can be prevented. A material that is easy to use can be used, and the range of material selection can be expanded.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a sealing plate portion of a sealed battery according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which the state shown in FIG.

FIG. 3 is a sectional view showing a fitting connection structure between an upper current contact and a lower current contact.

FIG. 4 is a sectional view showing a modification of the sealing plate structure.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Sealing plate 2 Metal thin plate 2a Swelling part 3 PTC 4 Upper current contact 5 Lower current contact 6 Sealing plate bottom plate 6a, 11a Pressurizing opening 8 Metal cap 10 Battery case 11 Lower electrode plate (sealing plate bottom plate)

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kazuhiko Watanabe 1006 Kazuma Kadoma, Kadoma City, Osaka Inside Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] 1. An end opening of a battery case accommodating a power generating element is hermetically sealed by a sealing plate, and a thin metal plate provided closer to the inside of the battery from a metal cap forming an electrode portion of the sealing plate raises the internal pressure of the battery. By deforming by
In a sealed battery having a structure for interrupting an energizing circuit from a power generating element to a metal cap, a lower current contact provided at the center of the sealing plate facing the inside of the battery and electrically connected to the power generating element at a center position thereof. A fixed sealing plate bottom plate, and an electrical connection is made to the metal cap provided on the outside of the battery adjacent to the sealing plate bottom plate, and a bulging portion gently bulging inward of the battery is formed at the center. And a metal sheet to which an upper current contact detachably fitted and connected to the lower current contact is fixed at a center position thereof. 2. The sealing plate bottom plate is formed so as to block the ventilation between the inside of the battery and the inside of the sealing plate, and breaks open when the pressure due to the battery internal pressure becomes a predetermined value or more, and the inside of the battery is opened. 2. The sealed battery according to claim 1, wherein a pressurized opening is formed for ventilating the space between the sealing plate and the inside of the sealing plate. 3. The sealed battery according to claim 1, wherein the bottom plate of the sealing plate is formed by resin molding, and the thinned portion is formed as a pressure opening.