JPH0883600A - Safety device for secondary battery and non-aqueous electrolyte secondary battery with safety device - Google Patents

Abstract

(57) [Summary] (Correction) [Purpose] The current cutoff operation is performed in response to the pressure increase in the battery, and the gas generated inside is discharged when the pressure in the battery exceeds a specified value. A battery lid 20 having an exhaust hole 20a and forming one electrode, and a rupture plate 22 that is deformed and ruptured according to gas pressure generated inside the battery to communicate with the exhaust hole 20a of the battery lid 20, The holder 24 for holding the same is provided with a hollow portion 24a which is adjacent to the rupture plate 22 and communicates with the inside of the battery, and one end of which is opposed to the rupture portion of the rupture plate 22 via the hollow portion 24a. A conductive elastic body 26 whose end is connected to the electrode lead 14a inside the battery is provided, and the conductive elastic body 26 elastically deforms due to a pressure increase change inside the battery, so that the electrode lead 14a inside the battery and the battery lid 20 are electrically connected. Safety device for secondary battery that cuts off the connection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for a secondary battery and a non-aqueous electrolyte secondary battery provided with the safety device, and more particularly to performing a current interruption operation in response to a pressure increase in the battery,
A safety device for a secondary battery and a non-aqueous electrolyte secondary device with a safety device that can prevent damage or rupture of the battery by discharging the gas generated inside when the pressure inside the battery exceeds a specified value. It concerns batteries.

[0002]

2. Description of the Related Art In recent years, miniaturization and portability of electronic devices have been rapidly progressing. Therefore, in this type of miniaturized electronic device, the secondary battery used as a power source,
It is required to have a small size and a high energy density. For this reason, a wide variety of secondary batteries are currently being researched and developed and put into practical use.

However, this type of secondary battery is
When the battery is ruptured due to gas generated in the battery during overcharging or overdischarging, or when the battery is thrown into a fire,
Expansion of the gas inside may cause an explosion or the like.

For example, in recent years, a substance capable of being doped or dedoped with lithium ions such as lithium, a lithium alloy, or a carbon material has been used as a negative electrode, while a lithium complex oxide such as a lithium cobalt complex oxide has been used as a positive electrode. It is known that the non-aqueous electrolyte secondary battery used has a high battery voltage, a high energy density, little self-discharge, and is excellent in cycle characteristics.
However, in this type of secondary battery, heat is generated during overcharge, and there is a risk of overheating. Further, during the overcharge, for example, lithium carbonate (Li ₂ CO ₃ ) contained in the positive electrode material is electrochemically decomposed to generate carbon dioxide gas (CO ₂ ).

Therefore, in the research and development of the secondary battery, the most important issue to be studied at present is to secure the safety.

From such a viewpoint, at present, as a means for ensuring the safety of the secondary battery, the pressure of the generated gas is used when the pressure reaches a predetermined value or more due to the generation of gas inside the battery. There have been proposed various safety valves that operate in accordance with the above, current cutoff means, and the like.

For example, as the safety valve, an elastic body such as synthetic rubber is used to open and close an exhaust hole provided in a battery cell, or a closing plate pressed against the exhaust hole by using spring elasticity. A method is adopted in which the gas generated inside is released to the outside by configuring the opening and closing.

As the current interruption means, the positive electrode lead is arranged so as to be electrically connected to the battery lid through the current interruption thin plate, and the current interruption thin plate is provided when the pressure inside the battery rises. There is proposed a structure in which a current is cut off by being pushed up and deformed, and by this deformation, the positive electrode lead is cut while leaving a portion welded to the thin plate for cutting off a current, leaving a portion (JP-A-5-242913). Issue).

[0009]

However, in the above-mentioned conventional secondary battery having the safety valve, the gas generated inside the battery can be discharged to the outside to prevent the battery from being damaged. Since there is no current interruption means, there is a problem that the overheat prevention at the time of overcharging is not achieved and the battery burns out. Further, in the one having the current interruption means as described above, by pushing up the current interruption thin plate due to the gas generation inside the battery and cutting it, the current can be interrupted and the charging can be stopped, When the pressure inside the battery returns to the specified normal pressure,
Since the cut current thin plate cannot be restored to its original state, there is a problem that charging cannot be continued again.

Therefore, an object of the present invention is to interrupt the current by temporarily interrupting the current in response to a pressure increase generated inside the battery during charging, etc., and when the pressure inside the battery returns to normal. The current cutoff can be restored and charging can be continued, and moreover, only the discharge of gas to the outside is smoothed against the pressure rise that occurs suddenly inside the battery when overcharging or overdischarging or throwing into fire. It is to provide a safety device for a secondary battery that can be achieved and a non-aqueous electrolyte secondary battery with a safety device.

[0011]

In order to achieve the above object, a safety device for a secondary battery according to the present invention is provided with a battery lid having an exhaust hole and forming one electrode, and a gas pressure generated inside the battery. A hollow portion formed of a rupture plate that is deformed and ruptured accordingly to communicate with the exhaust hole of the battery lid, and a holding member that holds the rupture plate, the holding member being adjacent to the rupture plate and communicating with the inside of the battery. A conductive elastic body is provided, one end of which is opposed to the rupture portion of the rupture plate through the hollow portion and the other end of which is connected to an electrode lead inside the battery. It is characterized in that the body is elastically deformed to interrupt the electrical connection between the electrode lead inside the battery and the battery lid.

In the secondary battery safety device, the rupture plate is made of a conductive material, and the rupture plate is held by a cage made of an insulating material having a hollow portion, and one end of the hollow portion is ruptured. A bottom plate made of a conductive material, which is opposed to the ruptured portion of the plate and has a through hole communicating with the inside of the battery at the other end and is connected to the electrode lead inside the battery, is arranged in the hollow portion of the cage. A conductive elastic body that is in contact with each of the rupture plate and the bottom plate may be housed and arranged, and the conductive elastic body may be compressed and deformed and separated from the rupture plate due to a change in pressure inside the battery.

In this case, the conductive elastic body may have a shape selected from a spherical shape, a prismatic shape, a cylindrical shape, a bellows shape or a diaphragm shape.

In the safety device for a secondary battery, the rupture plate is made of a conductive material, and a conductive spacer held by a guide member is arranged adjacent to the rupture plate to form a space portion, A through hole is provided in the guide member and the conductive spacer to connect the space and the inside of the battery, and the conductive rod is inserted into the through hole via an elastic body having an elastic force in the axial direction. It is also possible to make a part contact the conductive spacer and connect the other end base part to an electrode lead inside the battery so that the conductive rod is elastically displaced and separated from the conductive spacer due to a pressure increase change inside the battery. it can.

Further, the above-mentioned non-aqueous electrolyte secondary battery with a safety device comprises a non-aqueous electrolyte secondary battery comprising a lithium composite oxide positive electrode, a carbon material negative electrode, and a non-aqueous electrolyte. The electrode lead of one electrode is connected to the bottom plate of the safety device for the secondary battery described above, the electrode lead of the other electrode is connected to the battery can, and the safety device for the secondary battery is necked with the opening of the battery can. It can be configured such that it is housed and arranged via an insulating gasket between the above-mentioned parts.

As an alternative, it comprises a non-aqueous electrolyte secondary battery provided with a positive electrode of a lithium composite oxide, a negative electrode of a carbon material, and a non-aqueous electrolyte, and the electrode lead of the one electrode is for the secondary battery described above. The safety device is connected to the other end of the conductive rod, the electrode lead of the other electrode is connected to the battery can, and the safety device for the secondary battery is an insulating gasket between the opening and the necking part of the battery can. It is also possible to adopt a configuration in which it is housed and arranged via the.

[0017]

According to the present invention, when the inside of the battery is at a normal pressure, the conductive elastic body is in a state where one of the electrode leads inside the battery and the battery lid are electrically connected to each other. When the pressure rises due to the generation of gas inside the battery, the conductive elastic body housed in the hollow portion of the holding member is compressed and deformed to reduce its volume, and the conductive elastic body is separated from the rupture portion to separate the battery lid. The conduction is released and the current is cut off (charging is interrupted). After that, when the inside of the battery returns to a normal pressure, the conductive elastic body is restored to the initial state (volume), the electrode lead and the battery lid are electrically connected to each other, and the charging can be continued.

When the pressure inside the battery reaches a predetermined value or more due to the generation of gas during overcharging, overdischarging, or when the secondary battery is thrown into a fire, the rupture plate ruptures and the battery is destroyed. Gas is rapidly discharged to the outside of the battery from the exhaust hole of the lid,
It is possible to prevent damage or explosion of the secondary battery.

[0019]

EXAMPLES Examples of a safety device for a secondary battery and a non-aqueous electrolyte secondary battery with a safety device according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 shows an embodiment of a non-aqueous electrolyte secondary battery with a safety device according to the present invention. In this embodiment, the secondary battery is provided via an electrode group 12 made of a non-aqueous electrolyte housed inside a battery can 10 made of a carbonaceous material serving as a negative electrode, and a positive electrode lead 14 a of these electrode groups 12. And a safety device portion 18 including the positive electrode 16. Reference numeral 14b indicates a negative electrode lead of the electrode group 12, and the negative electrode lead 14b is directly connected to the battery can 10.

The safety device section 18 includes a required number of exhaust holes 20a.
A battery lid 20 provided as the positive electrode 16 on the uppermost part of the battery can 10, a rupturable plate 22 made of a conductive material and arranged in contact with the inner surface of the battery lid 20, and a lower portion of the rupturable plate 22. A cage 24 made of an insulating material having a hollow portion 24a attached to the cage, a conductive elastic body 26 housed in the hollow portion 24a of the cage 24 so as to come into contact with the rupturable plate 22, and the hollow A bottom plate 28 made of a conductive material having a required number of through holes 28a for contacting and holding the conductive elastic body 26 in the portion 24a and allowing the atmosphere inside the battery to enter and leave the hollow portion 24a; An insulating gasket 30 formed so as to enclose the outer peripheral edge portions of the battery lid 20 and the rupture plate 22 between the upper opening portion of the battery can 10 and the necking portion 10a in order to maintain the airtightness inside the battery. It is constructed from.

However, the battery lid 20 has an exhaust hole 20a for exhausting gas generated inside the battery,
It is preferable that one to three exhaust holes 20a be provided.

Further, the rupture plate 22 is made of a flexible conductive material such as pure aluminum, and it is preferable to provide a required number of grooves 22a at appropriate places in order to facilitate the rupture. The burst plate 22 may have a plate thickness of about 0.3 mm to 0.5 mm and a groove 22a depth of 0.1 mm when the burst pressure is about 10 atm. Although preferable, it is needless to say that the plate thickness, the groove depth, the shape, the number, and the like can be appropriately selected and set as necessary.

Further, the cage 24 is made of an insulating material such as polyethylene or polypropylene. Since the retainer 24 is placed in contact with the rupture plate 22, it needs to have a shape that matches the shape of the rupture plate 22. The shape of the hollow portion 24a is the conductive elastic body 26.
It is configured according to the shape of.

Therefore, the conductive elastic body 26 may be made of rubber in which a conductive filler is appropriately mixed. In this case, graphite whiskers, graphite, carbon, metal fibers or the like can be used as the conductive filler. Further, the conductive elastic body 26 has a spherical shape,
It is possible to appropriately select and use a prismatic column, a columnar column, a hollow body of these, or a structure having a structure that contracts in volume by an external pressure such as a bellows shape or a diaphragm shape.
Further, the conductive elastic body 26 is not limited to rubber, and any material can be suitably applied as long as the volume can be contracted and restored by external pressure or internal pressure.

The bottom plate 28 connects the electrode group 12 and the battery lid 20 via the conductive elastic body 26 to the positive electrode lead 14a.
Since it is necessary to connect via an aluminum plate, it is made of a conductive material such as an aluminum plate.

The insulating gasket 30 is made of a resin material, such as polyethylene or polypropylene, which insulates the positive electrode from the negative electrode and has a sealing function and flexibility and elasticity. Moreover, this gasket 3
0 has a washer shape, for example, so as to hold the outer peripheral edge portions of the battery lid 20 and the rupture plate 22 and to expose the head portion of the battery lid 20 and fix one end portion of the retainer 24. It is suitable.

Next, the operation of the safety device section 18 of the non-aqueous electrolyte secondary battery of the present embodiment having the above-mentioned structure will be described in detail below.

FIG. 2 shows a first operating state of the safety device section 18 in the non-aqueous electrolyte secondary battery shown in FIG. As shown in FIG. 1, the conductive elastic body 10 usually has a rupturable plate 22.
It is in contact with both the bottom plate 28 and the bottom plate 28, and holds the battery in a conducting state during discharging or charging. Therefore, for example, when gas is generated inside the battery due to overcharging or overheating, the pressure inside the battery rises and the pressure inside the hollow portion 24a of the retainer 24 communicating with the bottom plate 28 through the through hole 28a also rises. To do. In this case, the conductive elastic body 26 accommodated in the hollow portion 24a is
The volume is reduced by the isotropic pressure of the gas. Therefore, the conductive elastic body 26 is separated from both the rupture plate 22 and the bottom plate 28 by the volume reduction, and the current is cut off.
As a result, the battery can be prevented from being damaged and further damaged due to the generation of gas. If the pressure drops in this state, the conductive elastic body 26 quickly returns to the state shown in FIG.

FIG. 3 shows a second operating state of the safety device portion 18 in the non-aqueous electrolyte secondary battery shown in FIG. In the state shown in FIG. 3, more than the state shown in FIG.
This is the case when a high gas pressure is generated inside the battery. That is, in this case, the rupturable plate 22 causes plastic deformation toward the upper side of the battery due to the gas pressure. When the pressure is further increased, the rupture plate 22 starts to rupture from the groove 22a provided on the rupture plate 22, and finally a hole is opened in the rupture plate 22 so that gas can be discharged to the outside of the battery. This avoids battery explosion. In this case, the conductive elastic body 26 blocks the contact due to the plastic deformation and the rupture of the rupture plate 22 and blocks the current. After that, the conductive elastic body 2
No. 6 is immediately restored to the initial volume by discharging the gas to the outside of the battery, but the plastic deformation of the rupture plate 22 does not return, so that the rupture plate 22 cannot come into contact with it, so that the current is cut off inside the battery. Maintain a good condition.

FIG. 4 shows another embodiment of the non-aqueous electrolyte secondary battery provided with the safety device for a secondary battery according to the present invention. For convenience of explanation, the same components as those of the embodiment shown in FIGS. 1 to 3 will be designated by the same reference numerals and detailed description thereof will be omitted.

That is, in the embodiment shown in FIG. 4, in the safety device portion 18 of the above embodiment, a required space portion 31 is formed with respect to the inner surface portion of the rupture plate 22 in place of the retainer 24 and the bottom plate 28. The conductive spacer 34 held by the guide member 32 is arranged. In this case, the guide member 32 is made of an insulating material, and the through holes 32a, 3 are formed in the central portion of the guide member 32 so as to pass through together with the conductive spacers 34.
4a are provided respectively. However, the through holes 32a, 3
The one end portion side of the conductive rod 36 is inserted into 4a. That is, the conductive rod 36 has a shaft portion 36a having a required length,
One end thereof is inserted through the guide member 32 and the through holes 32a, 34a of the conductive spacer 34, and a flange portion 36b capable of making an inner surface contact with the conductive spacer 34 is formed at the tip portion thereof, and the other end portion thereof is provided with the electrode group 12. Forming a base portion 36c for conducting connection with the positive electrode lead 14a.

Further, in this embodiment, instead of the conductive elastic body 26 of the above-mentioned embodiment, the shaft portion 3 of the above-mentioned conductive rod 36 is used.
6a, between the base portion 36c and the guide member 32, an elastic body 38 such as a coil spring having a compressive elasticity is arranged on the outer periphery of the shaft portion 36a along the axial direction thereof, and the conductive rod is provided. The tip flange portion 36b of 36 is configured to elastically contact the conductive spacer 34. The other structure is almost the same as that of the above embodiment.

The operation of the safety device portion 18 in this embodiment thus constructed is such that the conductive rod 36 is displaced into the space portion 31 against the elasticity of the elastic body 38 when the pressure inside the battery rises. , The end flange portion 36b of the conductive rod 36
Is separated from the conductive spacer 34, the current is instantaneously cut off, and the conductive rod 36 is immediately returned to the original state.
Further, when a high gas pressure is generated inside the battery, in addition to the above operation, the rupture plate 22 starts to tear from the groove 22a provided on the rupture plate 22 and finally a hole is opened in the rupture plate 22. The gas can be discharged to the outside of the battery.

Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it goes without saying that various design changes can be made without departing from the spirit of the present invention. is there. For example, in the above-described embodiment, the battery lid 20 is configured as the positive electrode terminal portion and the battery can 10 is configured as the negative electrode terminal portion, but the battery lid 20 is configured as the negative electrode terminal portion and the battery can 1.
Even if 0 is set as the positive electrode terminal portion, the same effect can be obtained.

[0036]

As described above, the safety device for a secondary battery according to the present invention is deformed in accordance with the battery lid having the exhaust hole and forming one electrode, and the gas pressure generated inside the battery. A rupture plate that ruptures and communicates with the exhaust hole of the battery lid, and a holding member that holds the rupture plate, the holding member is provided with a hollow portion that communicates with the inside of the battery, and one end is provided through the hollow portion. A conductive elastic body is provided that faces the ruptured portion of the rupturable plate and has the other end connected to an electrode lead inside the battery, and the conductive elastic body is elastically deformed by a change in pressure inside the battery to cause an electrode inside the battery. By configuring so that the electrical connection between the lead and the battery lid is cut off, when the pressure rises due to the generation of gas inside the battery during charging, the conductive elastic body housed in the hollow portion of the holding member. Is compressed and deformed And the volume reduced, and separated the burst portion is released conduction the battery cover, current is interrupted (charging interruption).

After that, when the inside of the battery returns to a normal pressure, the conductive elastic body is restored to the initial state (volume), the electrode lead and the battery lid are electrically connected to each other, and the charging can be continued. .

When the pressure inside the battery reaches a predetermined value or more due to the generation of gas during overcharging, overdischarging, or when the secondary battery is thrown into a fire, the rupture plate bursts and the battery Gas is rapidly discharged to the outside of the battery from the exhaust hole of the lid,
It is possible to prevent damage or explosion of the secondary battery.

Further, in the safety device having the above structure, in the non-aqueous electrolyte secondary battery including the positive electrode of the lithium composite oxide, the negative electrode of the carbon material, and the non-aqueous electrolyte, the electrode lead of the one electrode is Connected to the lead connection portion of the safety device, the electrode lead of the other electrode is connected to the battery can,
By accommodating and disposing the safety device between the opening of the battery can and the necking via the insulating gasket, the non-aqueous electrolyte secondary battery having the above-mentioned safety characteristics can be easily obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of essential parts showing an embodiment of a non-aqueous electrolyte secondary battery provided with a safety device for a secondary battery according to the present invention.

FIG. 2 is a cross-sectional view of essential parts showing an operating state of the non-aqueous electrolyte secondary battery with a safety device shown in FIG.

FIG. 3 is a cross-sectional view of essential parts showing another operating state of the non-aqueous electrolyte secondary battery with a safety device shown in FIG. 1.

FIG. 4 is a cross-sectional view of essential parts showing another embodiment of the non-aqueous electrolyte secondary battery provided with the safety device for a secondary battery according to the present invention.

[Explanation of symbols]

 10 battery can 10a necking part 12 electrode group 14a positive electrode lead 14b negative electrode lead 16 positive electrode 18 safety device part 20 battery lid 20a exhaust hole 22 rupture plate 22a groove 24 retainer 24a hollow part 26 conductive elastic body 28 bottom plate 28a through hole 30 insulation Gasket 31 Space part 32 Guide member 32a Through hole 34 Conductive spacer 34a Through hole 36 Conductive rod 36a Shaft part 36b Tip flange part 36c Base part 38 Elastic body

Claims (6)

[Claims] 1. A battery lid having an exhaust hole and forming one electrode, and a rupture plate that is deformed and ruptured according to a gas pressure generated inside the battery to communicate with the exhaust hole of the battery lid.
A holding member for holding the rupturable plate, the holding member is provided with a hollow portion adjacent to the rupturable plate and communicating with the inside of the battery, and one end is opposed to the ruptured portion of the rupturable plate through the hollow portion. In addition, a conductive elastic body that connects the other end to an electrode lead inside the battery is provided, and the conductive elastic body is elastically deformed due to a pressure increase change inside the battery, so that the electrode lead inside the battery and the battery lid are electrically connected. A safety device for a secondary battery, which is configured to shut off the battery. 2. The rupture plate is made of a conductive material, and the rupture plate is held by a cage made of an insulating material having a hollow portion, and one end of the hollow portion is opposed to the rupture portion of the rupture plate, A bottom plate made of a conductive material that has a through hole communicating with the inside of the battery and is connected to the electrode lead inside the battery is arranged opposite to the other end, and contacts the rupture plate and the bottom plate inside the hollow portion of the cage. 2. The safety device for a secondary battery according to claim 1, wherein a conductive elastic body is housed and arranged, and the conductive elastic body is compressed and deformed by a change in pressure inside the battery to separate from the rupture plate. 3. The safety device for a secondary battery according to claim 2, wherein the conductive elastic body has a shape selected from a spherical shape, a prismatic shape, a cylindrical shape, a bellows shape, or a diaphragm shape. 4. The rupturable plate is made of a conductive material, a conductive spacer held by a guide member is arranged adjacent to the rupturable plate to form a space, and a through hole is provided in the guide member and the conductive spacer. The space portion and the inside of the battery are communicated with each other, the conductive rod is inserted into the through hole through an elastic body having an elastic force in the axial direction, and one end flange portion of the conductive rod is brought into contact with the conductive spacer, and other 2. The safety device for a secondary battery according to claim 1, wherein the end base is connected to an electrode lead inside the battery, and the conductive rod is elastically displaced by the change in pressure inside the battery to separate from the conductive spacer. 5. A secondary battery according to claim 2, comprising a non-aqueous electrolyte secondary battery comprising a lithium composite oxide positive electrode, a carbon material negative electrode, and a non-aqueous electrolyte. Connected to the bottom plate of the battery safety device, the electrode lead of the other electrode is connected to the battery can, the secondary battery safety device through the insulating gasket between the opening of the battery can and the necking portion. A non-aqueous electrolyte secondary battery with a safety device that is stored and arranged. 6. A secondary battery according to claim 4, comprising a non-aqueous electrolyte secondary battery comprising a lithium composite oxide positive electrode, a carbon material negative electrode, and a non-aqueous electrolyte. Connect to the other end of the conductive rod of the battery safety device, connect the electrode lead of the other electrode to the battery can, and insulate the secondary battery safety device between the opening of the battery can and the necking portion. A non-aqueous electrolyte secondary battery with a safety device, which is stored and arranged via a gas-permeable gasket.