JPH09134715A - Battery with explosion proof function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery of an enhanced reliability, which can positively maintain the current shut-off condition. SOLUTION: A battery concerned is composed of a battery case 1 of metal in cylindrical form having bottom, a power generating element 2 accommodated in the case 1, a lead 8 connected with one of the electrodes of this element 2, and a lid element A connected with the lead 8 and attached sealedly to the opening of the case 1 through an insulative outside gasket 7. The lid element A has an inner terminal plate 5, an insulator ring 6, a flexible intermediate pressure-sensitive plate 4, a ring-shaped PTC element 9, an outer terminal plate 3, an inside gasket 11, and a caulking ring 12, wherein a ring-shaped elastic member 10 is pinched in compressed condition between the pressure-sensitive plate 4 and terminal plate 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery having an explosion-proof function, and more particularly to a technique for a chargeable / dischargeable battery such as a lithium ion secondary battery.

[0002]

2. Description of the Related Art Conventionally, as an explosion-proof function of a lithium-ion secondary battery, for example, as disclosed in JP-A-2-288063, the temperature rise inside the battery is suppressed within the initial period to prevent ignition of the battery. In addition, it is known that gas is vented when the pressure inside the battery rises to prevent the battery from exploding. Such a battery sealing structure has a cylindrical battery case 21 and an electrode group 2 housed in the battery case 21 as shown in the sectional view of the main part of FIG.
6, a terminal plate 25 attached to the open end 21a of the battery case 21 via a sealing gasket 22 and having a gas vent hole 20 formed therein, and one end side attached to the electrode group 26 and the other end side via an explosion-proof mechanism. It is composed of a lead 28 electrically connected to the terminal plate 25.

The explosion-proof mechanism includes a metallic sealing plate 23 disposed below the terminal plate 25, a lead stripper 24 disposed below the sealing plate 23, the sealing plate 23 and the lead stripper 24. It is mainly composed of an intermediate fitting body 30 fitted in between. The sealing plate 23 has a disk-like shape and has a protrusion 23a protruding downward in the center thereof, and a thin portion 23b radially extending from the vicinity of the root of the protrusion 23a is formed on the upper surface of the sealing plate 23. The upper end 2 of the battery case 21 through the gasket 22 together with the plate 25
It is crimped and fixed to 1a. The lead stripper 24 is made of an insulating material and has a disk shape.
An insertion hole 24a into which the protrusion 23a of the sealing plate 23 is inserted is formed in the center thereof. Then, the intermediate fitting body 30
Is formed of an insulating material and has a disk shape, and is recessed and fitted between the stripper 24 and the sealing plate 23 to be integrally connected. The lead 28 having one end attached to the electrode group 26 has a lead stripper 24 at the other end.
Is connected by ultrasonic welding to the lower surface of the projection 23a and the lower surface of the projection 23a facing downward from the insertion hole 24a, and extends beyond the lower surface of the projection 23a.

In such an explosion-proof mechanism, as a pressure-sensitive shut-off function, for example, when overcharging or short-circuiting progresses and gas is generated / filled due to chemical change inside the battery and the battery internal pressure rises, the sealing plate 23 serves as a terminal plate. The lead 28 is pressed toward 25 and deformed upward, and the lead 28 welded to the lower surface of the protrusion 23a is separated from the sealing plate 23 at the welded portion to interrupt the current.

When the internal pressure of the battery further rises, the sealing plate 23 bulges upward, and when the pressure exceeds the set pressure, the thin portion 23b is broken and the gas is safely discharged from the gas vent hole of the external terminal plate. This is the internal pressure release function.

[0006]

When the internal pressure of the battery rises due to, for example, an overcharged state during charging, the sealing plate 23 is deformed upward, as described above, and the protrusion 23a and the lead 2 are formed.
The welded portion of 8 is peeled off, and the conductive path inside the battery is cut off. In this state, when the battery internal pressure further rises and the battery internal pressure decreases due to the operation of the internal pressure releasing function, the protrusion 23a of the sealing plate 23 moved upward returns to the original position and is connected to the lead 28, There was a problem that there is a possibility that it will be conducted again.

When the internal pressure of the battery rises very slowly, the sealing plate 23 and the lead 28 are welded to each other due to external vibration or the like even if the sealing plate 23 moves upward and the peeling occurs to interrupt the current. There may be a problem that the parts come into contact again to cause a hunting state in which a current flows or the current is cut off again.

As described above, when the conductive path inside the battery is re-conducted or becomes hunting while the internal pressure releasing function is working, metallic lithium is deposited in the form of needles, which is unlikely to dissolve, that is, dendrite is generated. It is possible that it will end up.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a battery having an explosion-proof function that can reliably maintain a current interruption state and has improved reliability.

[0010]

In order to achieve the above-mentioned object, a battery having an explosion-proof function of the present invention is a bottomed tubular metal battery case, a power generating element housed in the battery case, and a power generating element. A lead connected to one of the electrodes,
A battery comprising a lid element that is electrically connected to the lead and is attached to the opening of the battery case via an insulating outer gasket to close the opening, wherein the lid element has a gas vent hole. A formed metal internal terminal plate, an intermediate pressure-sensitive plate made of a flexible metal plate that is easily broken, and a gas vent hole formed above the intermediate pressure-sensitive plate and electrically connected to the intermediate pressure-sensitive plate. And a metal external terminal plate formed with, the tips of the leads are connected to the lower surface of the internal terminal plate, the intermediate pressure-sensitive plate is laminated above the internal terminal plate, and both members are The intermediate pressure-sensitive plate is locally fixed at the central portion so that it is electrically connected only at the fixed portion and an elastic member is interposed between these members in a compressed state. And the connection between the internal terminal board and The elastic member when the cross is to prevent the said intermediate sensitive plate thickness thereof is elastically restored increases the reconnection of the internal terminal plates.

Preferably, an insulating ring is sandwiched between the intermediate pressure sensitive plate and the internal terminal plate, and the intermediate pressure sensitive plate is electrically connected to the external terminal plate via a positive temperature coefficient resistance element. The entire laminate of the inner terminal plate, the insulating ring, the elastic member, the intermediate pressure sensitive plate, the positive temperature coefficient resistance element and the outer terminal plate is fitted into the inner periphery of the caulking ring via an inner gasket. It is integrated by crimping.

The elastic member is a sheet-shaped elastic body or a spring or plate-shaped spring.
Natural rubber, styrene butadiene rubber, butadiene rubber,
It is preferably made of at least one material selected from the group consisting of ethylene propylene rubber, nitrile rubber, silicon rubber, polyethylene terephthalate, polybutylene terephthalate, nylon, polyphenylene sulfide, or tetrafluoroethylene.

Further, the elastic member is a spring made of a spring-shaped or plate-shaped metal whose surface is at least partially insulated, and the metal is made of at least one of iron, stainless steel, nickel, and titanium. It is preferable that

In the battery having the explosion-proof function of the present invention as described above, since the elastic member is sandwiched between the intermediate pressure sensitive plate and the internal terminal plate in a compressed state, the internal pressure of the battery increases. If the central part of the intermediate pressure sensitive plate moves upward and the welding point peels off and the conductive path inside the battery is cut off,
Since the compressed state of the elastic member is released, the elastic member elastically returns to increase its thickness. This maintains the state in which the central portion of the intermediate pressure sensitive plate is separated from the upper surface of the internal terminal plate. Therefore, even if the battery internal pressure decreases, the intermediate pressure-sensitive plate and the internal terminal plate are prevented from coming into contact with each other again to be electrically connected, and the current cutoff state is reliably maintained.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 1 shows a main structure of a battery having an explosion-proof function according to a preferred embodiment of the present invention. The basic configuration of this battery is a cylindrical metal battery case 1 with a bottom.
An electric power generating element 2 housed in the battery case 1, an aluminum lead 8 connected to one electrode of the electric power generating element 2, and an outer polypropylene gasket electrically connected to the lead 8 and having an insulating property. And a lid element A that is hermetically attached to the opening of the battery case 1 via 7.

The lid element A comprises an aluminum inner terminal plate 5, a polypropylene insulating ring 6, a flexible aluminum intermediate pressure sensitive plate 4, a ring-shaped positive temperature coefficient resistance element,
That is, PTC (Positive Temperature Coefficient) element 9, external terminal board 3, polypropylene inner gasket 1
1 and a caulking ring 12 made of stainless steel, and in particular, a ring-shaped elastic member 10 which is a characteristic part of the present invention is interposed between the intermediate pressure sensitive plate 4 and the internal terminal plate 5 in a compressed state.

A plurality of gas vent holes 3a and 5a are formed in the external terminal plate 3 and the internal terminal plate 5, respectively, and the intermediate pressure-sensitive plate 4 is formed with a protrusion 4a and a thin portion 4b protruding downward in the central portion. ing.

The elastic member 10 is formed by punching a sheet-shaped elastic body made of styrene-butadiene rubber (SBR) into a ring shape, and the inner diameter of the elastic member 10 is the protrusion 4 a of the intermediate pressure-sensitive plate 4.
Is set to a size that can be inserted.

Explaining the procedure for assembling the lid element A, first,
After fitting the inner gasket 11 into the inner periphery of the crimp ring 12, the inner terminal plate 5 is fitted into the inner periphery of the inner gasket 11. Then, the insulating ring 6 and the ring-shaped elastic member 10 are placed at predetermined positions on the upper surface of the internal terminal plate 5. After that, the intermediate pressure-sensitive plate 4 is placed on the upper surfaces of the insulating ring 6 and the ring-shaped elastic member 10, and the protrusion 4a of the intermediate pressure-sensitive plate 4 is inserted into the inner peripheral side of the insulating ring 6. Next, the protrusion 4a of the intermediate pressure sensitive plate 4 and the upper surface of the internal terminal plate 5 are ultrasonically welded, resistance welded, or laser welded. At this time, the elastic member 10 is clamped between the intermediate pressure-sensitive plate 4 and the internal terminal plate 5 in a compressed state by pressing the lower end of the protrusion 4a of the intermediate pressure-sensitive plate 4 against the upper surface of the internal terminal plate 5. The strength of welding is set so that the welded portion is broken at a predetermined battery internal pressure, and the size and shape of the elastic member 10 are set in advance so that the elastic restoring force of the elastic member 10 is lower than the welding strength. After the welding is completed, the elastic member 10 is kept compressed and held between both members. Then, the PTC element 9 and the external terminal plate 3 are sequentially laminated on the upper surface of the intermediate pressure-sensitive plate 4, and the upper end portion of the caulking ring 12 is curled inward to form an integral lid element A.

One end of the lead 8 drawn out from the power generating element 2 is spot-welded to the central portion of the lower surface of the internal terminal plate 5 constituting the lid element A described above. Then, after the lid element A is fitted on the inner circumference of the outer gasket 7, the battery case 1
The opening portion is curled inward and caulked, and the outer gasket 7 is compressed to seal the battery case 1.

In the above structure, the intermediate pressure-sensitive plate 4 and the internal terminal plate 5 are connected to each other by the projection 4a of the intermediate pressure-sensitive plate 4, and the two members are electrically connected only at this connection portion, and the intermediate pressure-sensitive plate 4 and the intermediate pressure-sensitive plate 4 are connected. The external terminal board 3 is electrically connected via the PTC element 9.

When a gas having such a structure is used and gas is generated inside due to overcharge or the like, the gas pressure in the battery case 1 acts on the intermediate pressure sensitive plate 4 through the gas vent hole 5a of the internal terminal plate 5. If the battery pressure rises abnormally,
The intermediate pressure-sensitive plate 4 is deformed so as to bulge upward, the welding point between the protrusion 4a and the internal terminal plate 5 is separated, and the two members are separated from each other. As a result, the conductive path in the battery connected to the external terminal board 3 is cut off (pressure-sensitive cutoff function).

The elastic member 10 which is sandwiched between the intermediate pressure-sensitive plate 4 and the internal terminal plate 5 by compression is released from the compressed state due to the separation of the welding between the protrusion 4a and the internal terminal plate 5, and before compression. Expands and restores to the state of, and the wall thickness increases. Therefore, the protrusion 4 a of the intermediate pressure sensitive plate 4 maintains a state of being separated from the upper surface of the internal terminal plate 5.

Furthermore, the internal pressure of the battery rises and the intermediate pressure sensitive plate 4
When is further deformed, the thin portion 4b is finally broken, and the gas in the battery case 1 is released to the outside (internal pressure releasing function).

At this time, even if the internal pressure of the battery decreases, as described above, the elastic restoring force of the elastic member 10 causes the intermediate pressure sensitive plate 4 to move.
Since the protruding portion 4a maintains a state in which it is separated from the upper surface of the internal terminal plate 5, it is reliably prevented that both members come into contact with each other again and become conductive, and the current interruption state is reliably maintained.

When the battery temperature rises abnormally, the resistance value of the PTC element 9 inserted in the battery conductive path connected to the external terminal board 3 increases, and the charging or discharging current is narrowed down (temperature-sensitive cutoff). function).

The order of operation of the pressure-sensitive shutoff function and the temperature-sensitive shutoff function varies depending on the state of the battery, but the safety of the battery is ensured regardless of which function works first.

Further, if the PTC element 9 is eliminated and the external terminal board 3 is directly laminated on the intermediate pressure-sensitive plate 4, the explosion-proof function of the type without the temperature-sensing shut-off function is obtained, but the battery is abnormal. When the temperature rises, the internal pressure of the battery also rises above the level, so sufficient safety is secured.

It is preferable that the elastic member 10 has resistance to electrolytic solution and insulation, and in addition to the above-mentioned members,
Natural rubber, butadiene rubber, ethylene propylene rubber,
A sheet made of nitrile rubber or silicon rubber may be punched into a ring shape, or a spring or plate spring made of polyethylene terephthalate, polybutylene terephthalate, nylon, polyphenylene sulfide, tetrafluoroethylene, or the like may be used. In addition to these, a spring spring or a leaf spring made of metal such as iron, stainless steel, nickel, or titanium can be applied. In this case, the elastic member 10 is provided between the internal terminal plate 5 and the intermediate pressure sensitive plate 4.
In order to prevent electrical conduction through the, contact surface for one or both members, or the entire surface is coated with an epoxy resin that is chemically stable and has a large mechanical strength and good insulation. Insulate.

Although the inner gasket 11 and the outer gasket 7 are the only members that come into contact with the caulking ring 12, they are all insulative. Therefore, the caulking ring 12 is electrically insulated from the power generating element 2 and the external terminal 3. Therefore, the caulking ring 12
It is possible to reliably prevent the occurrence of corrosion due to the electrical cause of.

Therefore, the degree of freedom in selecting the material for the caulking ring 12 is increased, and stainless steel can be used as in the embodiment of the present application. For this reason, it is not necessary to use expensive precious metals such as gold and platinum or aluminum that does not have sufficient crimping force.

By using stainless for the caulking ring 12, the lid element A can be given sufficient strength. Therefore, even if a horizontal stress is applied when the battery case 1 is curled in the assembling process, it can sufficiently withstand. Therefore, this stress does not give harmful stress to the welded portion of the protrusion 4a of the intermediate pressure-sensitive plate 4 and the internal terminal plate 5, and the reliability of the pressure-sensitive shutoff function can be improved.

Further, the inner terminal plate 5, the insulating ring 6, the intermediate pressure sensitive plate 4, the PTC element 9, the outer terminal plate 3, and the elastic member 1 are provided.
0, the inner gasket 11, and the caulking ring 12 are fitted inside the caulking ring 12 and integrated as the lid element A. Therefore, the lid element A is assembled in advance, and when the battery is assembled, the lid element A is placed in the opening portion of the battery case 1 to form the outer gasket 7.
Assembling is improved because it is only necessary to mount it via the.

[0034]

As described above in detail, in the battery having the explosion-proof function of the present invention, the internal pressure of the battery rises and the welding point between the intermediate pressure-sensitive plate and the internal terminal plate is peeled off. When the pressure cutoff function is activated, the current cutoff state can be reliably maintained even if the battery internal pressure drops, and the reliability of the explosion proof function is improved.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of a main part of a conventional battery having an explosion-proof function.

[Explanation of symbols]

1 Battery Case 2 Power Generation Element 3 External Terminal Plate 3a Gas Venting Hole 4 Intermediate Pressure Sensing Plate 4a Projection 4b Thin Wall 5 Internal Terminal Board 5a Gas Venting Hole 6 Insulation Ring 7 Outer Gasket 8 Lead 9 PTC Element (Positive Temperature Coefficient Resistance Element) 10 elastic member 11 inner gasket 12 caulking ring

Claims (4)

[Claims] 1. A bottomed cylindrical metal battery case (1),
A power generating element (2) housed in the battery case (1),
The battery case (1) is connected to a lead (8) connected to one electrode of the power generating element (2) and an outer gasket (7) electrically connected to the lead (8) and having an insulating property. A lid element (A) which is attached to the opening portion of the battery and closes the opening portion, the lid element (A) is a metal internal terminal plate (5) in which a vent hole is formed, and the lid element (A) is broken. Intermediate pressure plate (4) made of a flexible metal plate
And a metal external terminal plate (3) having a gas vent hole formed above the intermediate pressure sensitive plate (4) in a state of being electrically connected to the intermediate pressure sensitive plate (4). ) Is connected to the lower surface of the internal terminal plate (5), the intermediate pressure-sensitive plate (4) is laminated above the internal terminal plate (5), and both members are connected to the intermediate pressure-sensitive plate (4). The central portion (4c) is locally fixed so that it is electrically connected only at the fixed portion and an elastic member (10) is interposed between these two members in a compressed state, When the connection between the pressure sensitive plate (4) and the internal terminal plate (5) is cut off, the elastic member (1)
0) is a battery having an explosion-proof function, which is elastically restored to increase its wall thickness to prevent reconnection between the intermediate pressure-sensitive plate (4) and the internal terminal plate (5). 2. An insulating ring (6) is sandwiched between the intermediate pressure sensitive plate (4) and the internal terminal plate (5), and the intermediate pressure sensitive plate (4) has a positive temperature coefficient resistance element (9). Is electrically connected to the external terminal board (3) through the internal terminal board (5), the insulating ring (6), and the elastic member (1).
0), the intermediate pressure sensitive plate (4), the positive temperature coefficient resistance element (9) and the outer terminal plate (3) are entirely laminated through the inner gasket (11) to the inner circumference of the caulking ring (12). The battery having an explosion-proof function according to claim 1, wherein the battery has an explosion-proof function and is integrated by being caulked. 3. The elastic member (10) is a sheet-shaped elastic body or a spring-shaped or plate-shaped spring, and is made of natural rubber, styrene-butadiene rubber, butadiene rubber, ethylene-propylene rubber, nitrile rubber, silicon rubber. , Polyethylene terephthalate, polybutylene terephthalate, nylon, polyphenylene sulfide,
Alternatively, the battery having an explosion-proof function according to claim 1 or 2, which is made of a material selected from at least one selected from the group consisting of tetrafluoroethylene. 4. The elastic member (10) is a spring made of a spring-shaped or plate-shaped metal whose surface is at least partially insulated, and the metal is one of iron, stainless steel, nickel, and titanium. The battery having an explosion-proof function according to claim 1, wherein the battery has at least one kind.