JPH09106803A - Battery safety device - Google Patents

Abstract

(57) Abstract: A battery safety device capable of preventing the battery case from exploding due to an increase in internal pressure. A power supply path of a safety device is a lead wire.
→ Terminal 17 of conductor case 6 → PTC plate 12a → annular terminal 12b → contact piece 15 → electrode lid 16 When gas is generated from the power generation element 2 and the pressure in the battery case 3 rises, the aluminum foil 8 expands due to the pressure in the battery case 3, and the spacer 10 is lifted. When the spacer 10 is raised, the spacer 10 pushes up the central portion of the disc spring 11 and reverses the disc spring 11. When the disc spring 11 is reversed, the disc spring 11 pushes up the contact piece 15 to separate the contact piece 15 from the annular terminal 12b and disconnect the energization path of the safety device 5. As a result, the current is cut off and the generation of gas from the power generation element 2 is suppressed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery safety device which prevents the battery case from exploding due to an increase in pressure in the battery case due to overcharge, short circuit or the like.

[0002]

2. Description of the Related Art In recent years, along with the widespread use of video cameras, headphone stereos, mobile phones, etc., there is an increasing demand for improving the heavy load characteristics of a secondary battery as a power source and increasing the energy density. As a secondary battery that satisfies this demand, a nickel-cadmium battery that has been conventionally used can be cited, but recently, a lithium battery has been attracting attention, and development and use of this lithium battery have been activated.

[0003]

The secondary battery of this type is
Generally, it has a sealed structure. Therefore, when gas is generated from the power generation element due to overcharge, short circuit, or the like, the pressure inside the battery case rises, which causes deterioration of battery performance. Furthermore, the battery case may explode, damaging surrounding equipment and damaging nearby persons.

Therefore, an object of the present invention is to provide a battery safety device capable of preventing the battery case from exploding due to an increase in internal pressure.

[0005]

In order to solve the above-mentioned problems, a safety device according to a first aspect of the present invention covers a hole of a battery case that hermetically seals a power generating element and seals the surface of the power generating element. A sealing sheet that faces the inside of the battery case through the hole, is arranged on the back surface side of the sealing sheet, and is disposed on the back surface side of the disk spring and the disc spring that is inverted by receiving the internal pressure of the battery case through this sealing sheet. , And switch means for switching in conjunction with the reversal of the disc spring.

That is, since the pressure inside the battery case is transmitted to the disc spring through the sealing sheet, when the pressure inside the battery case exceeds the allowable pressure due to overcharge or short circuit, the dish The spring is reversed, and the switch means is switched accordingly. Therefore, if the switch means is inserted in the energization path, when the pressure in the battery case exceeds the allowable pressure, the current can be cut off to avoid an overcurrent or short circuit condition.

Further, the safety device according to the second aspect of the present invention includes a sealing sheet which covers and seals the hole of the battery case for hermetically sealing the power generating element, the surface of which faces the inside of the battery case through the hole. The moving piece stacked on the back surface of the encapsulating sheet and the encapsulating sheet expands toward the outside of the battery case due to the internal pressure of the battery case, and when the moving piece moves, the moving piece interlocks with the moving piece. And switch means for switching.

Here, the pressure in the battery case is transmitted to the switch means through the sealing sheet and the moving piece, and the switch means is switched. Therefore, if this switch means is inserted in the energization path, the current can be shut off when the pressure in the battery case exceeds the allowable pressure.

The safety device according to a third aspect of the present invention includes a telescopic bellows container which covers the hole of the battery case for hermetically sealing the power generating element and seals the power generating element, and which projects inside the battery case. The moving piece arranged inside the bellows container, the disc spring that is superposed on the moving piece and expands toward the inside of the battery case, and the disc spring when the disk spring expands toward the inside of the battery case. Contact with each other, the bellows container contracts due to the internal pressure of the battery, the moving piece moves and presses the disc spring, and when the disc spring is reversed, at least one of the pair of terminals is separated from the disc spring. I have it.

The safety device according to the third aspect has a structure in which the pressure in the battery case is transmitted to the disc spring via the bellows container and the moving piece, and when the disc spring is reversed, at least the pair of terminals is at the same time. One of them is separated from the disc spring, and these terminals are separated from each other. Therefore, if the disc spring and each terminal are inserted in the energizing path, the current can be interrupted when the pressure in the battery case rises.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a secondary battery to which an embodiment of the safety device according to claim 1 is applied. In this secondary battery 1, the power generation element 2 is sealed in a battery case 3, and the safety device 5 is supported on the upper end of the battery case 3 by caulking with an insulator 4 interposed.

As shown in FIG. 2, the safety device 5 includes a gasket 7, an aluminum foil 8, a cylindrical body 9, a spacer 10, a disc spring 11, a PTC plate 12a, an annular terminal 12b, and an insulating material inside a conductor case 6. Put the seals 13 on top of each other, P
The electrode cover 1 in which the moving piece 14 is inserted into the holes of the TC plate 12a and the annular terminal 12b, and then the contact piece 15 is resistance-welded thereon.
6, the periphery of the conductor case 6 is caulked, and the periphery of the electrode lid 16 is sandwiched.

The PTC plate 12a is a positive temperature coefficient thermistor having a characteristic that it has a low resistance at room temperature, but the resistance increases sharply when the temperature exceeds a predetermined temperature. As will be described later, the safety is improved. It is provided for.

A hole 6a is formed in the bottom of the conductor case 6. The aluminum foil 8 faces the inside of the secondary battery 1 through the hole 6 a of the conductor case 6. Further, a terminal 17 is hung on the peripheral edge of the hole 6 a, and the terminal 17 is connected to the power generating element 2 through a lead wire 18.

The contact piece 15 of the electrode lid 16 has sufficient elasticity, and its tip is in contact with the annular terminal 12b.

The energizing path of the safety device 5 is the lead wire 1.
8 → terminal 17 of conductor case 6 → PTC plate 12a → annular terminal 12b → contact piece 15 → electrode lid 16.

In such a structure, when an overcharge or a short circuit occurs and an overcurrent flows, the PTC of the energizing path is
The plate 12a generates heat, the temperature of the PTC plate 12a rises, and the resistance of the PTC plate 12a becomes extremely large. As a result, the overcurrent is suppressed, the current becomes small, and the overcharge or short-circuit state is avoided.

Despite the suppression of overcurrent by the PTC plate 12a, when gas is generated from the power generating element 2 and the pressure in the battery case 3 rises, the aluminum foil 8 is transferred to the inside of the battery case 3 as shown in FIG. Swelled by the pressure of the spacer 1
0 rises. When the spacer 10 is lifted, the spacer 10 pushes up the central portion of the disc spring 11,
The disc spring 11 is reversed. When the disc spring 11 is reversed, the moving piece 14 pushes up the contact piece 15 to separate the contact piece 15 from the annular terminal 12b, and disconnects the energization path of the safety device 5. As a result, the current is cut off and the generation of gas from the power generation element 2 is suppressed.

Even though the current is cut off in this way,
When the pressure inside the battery case 3 continues to rise, the aluminum foil 8 is broken as shown in FIG. 4, and the gas inside the battery case 3 becomes
From the hole 11a of the disc spring 11 to the inside of the electrode lid 16, the light is emitted from the hole 16a of the electrode lid 16 to the outside. This prevents the battery case 3 from exploding.

That is, in this secondary battery 1, P
Due to the triple action of suppressing the overcurrent by the CT plate 12a, cutting the energization path by reversing the disc spring 11, and releasing the internal gas by breaking the aluminum foil 8, the secondary battery 1
The explosion-proof is done.

Instead of the aluminum foil 8, another type of metal foil or synthetic resin film may be applied alone, or a combination of these may be applied. Further, when a metal foil is applied, a resin film that prevents electrolytic corrosion of the metal foil may be applied.

FIG. 5 shows a secondary battery to which an embodiment of the safety device according to claim 2 is applied. In this secondary battery 21, a safety device 25 is provided on an inner lid 24 of a battery case 23 that seals the power generation element 22. The inner lid 24, together with the electrode lid 26, is supported on the upper end of the battery case 23 by caulking with an insulator 27 interposed.

The safety device 25 is as shown in FIG. 6, and the aluminum foil 29 and the annular plate 30 are overlapped and welded (or bonded) to the edge of the lower opening of the substantially cylindrical conductor case 28. )doing. The moving piece 31 and the insulating frame 32 are housed in the conductor case 28, the moving piece 31 is placed on the aluminum foil 29, and the moving piece 31 is arranged in the cavity 32 a of the insulating frame 32.

A conductive support 33 is provided in a protruding manner in the cavity 32a of the insulating frame 32, and the contact piece 34 is supported by the conductive support 33. The contact piece 34 is formed by punching out a conductive plate, and has a support portion 34a, a spring portion 34b, and a contact portion 34c. Here, since the left end of the spring portion 34b is fixed at a position above the support portion 34a, the contact portion 34c is biased downward, and the contact portion 34c is in contact with the terminal 35.

The terminal 35 is connected to the electrode lid 26 through a lead wire 36. The other terminal 37 is connected to the power generation element 22 through the lead wire 38, the conductor case 28, and the lead wire 39.

The energizing path of the safety device 25 is lead wire 39 → conductor case 28 → lead wire 38 → terminal 37 → conductive support 33 → contact piece 34 → terminal 35 → lead wire 36 → electrode cover 26. .

When gas is generated from the power generation element 22 and the pressure inside the battery case 23 rises, the aluminum foil 29 expands due to the pressure inside the battery case 23, and the moving piece 31 is lifted up, as shown in FIG. . When the moving piece 31 is lifted, the protrusion 31a of the moving piece 31 pushes up the contact piece 34, separates the contact piece 34 from the terminal 35, and disconnects the energization path of the safety device 25. As a result, the current is cut off and the generation of gas from the power generation element 22 is suppressed.

As the contact piece 34, various ones having the same function are manufactured, and an appropriate one may be selected from these.

Also in this safety device 25, similarly to the embodiment of the invention of claim 1, suppression of overcurrent by the PTC plate and release of internal gas due to destruction of the aluminum foil may be applied. .

FIG. 8 shows an embodiment of the safety device according to claim 3. The safety device 41 is applied instead of the safety device 25 of the secondary battery 21 shown in FIG. 5, and is provided on the inner lid 24 of the secondary battery 21.

In the safety device 41, the edge of the bellows container 43 and the annular plate 44 are overlapped and bonded to the edge of the lower opening of the substantially cylindrical conductor case 42. This bellows container 43
Is made of synthetic resin, has a bottom 43a, and is open on the upper side.

Inside the conductive case 42, there is a cylindrical body 42a.
, The moving piece 45 is put into the bellows container 43 through the cylindrical body 42a, and the disc spring 46 and the insulating frame 4 are placed thereon.
7 are sequentially stacked.

The disc spring 46 contacts the two terminals 48, 49 of the insulating frame 47 and energizes the terminals 48, 49. One terminal 48 is connected to the electrode lid 26 of the secondary battery 21 via a lead wire 50. The other terminal 49 is connected to the lead wire 51 and the conductor case 42.
And the lead wire 52, and is connected to the power generation element 22.

The energizing path of the safety device 41 is lead wire 52 → conductor case 42 → lead wire 51 → terminal 49 → disc spring 46 → terminal 48 → lead wire 50 → electrode lid 26.

Here, when the pressure inside the secondary battery 21 rises, the bellows container 43 shrinks and the moving piece 45 is lifted as shown in FIG. 9, and the disc spring 46 is caused by the convex portion 45a of the moving piece 45. The center of is pushed up and this disc spring 46
Is reversed and separated from the terminals 48 and 49. As a result,
The energization path of the safety device 41 is cut off, the current is cut off, and the generation of gas is suppressed.

The bellows container 43 is not limited to synthetic resin and may be made of other materials. Further, when the disc spring 46 is reversed, the disc spring 46 may be separated from at least one of the terminals 48 and 49.

Also in this safety device 41, similarly to the embodiment of the invention of claim 1, suppression of overcurrent by the PTC plate and release of internal gas by destruction of the aluminum foil may be applied.

By the way, in the safety device 41, the operation can be inspected by the following procedure without destroying the safety device 41.

First, it is checked whether or not the terminals 48 and 49 of the safety device 41 are electrically connected. If there is no continuity, it is a defective product.

Next, the bellows container 43 is pushed up and contracted, the moving piece 45 is lifted, and the disc spring 46 is reversed. At this time, if the terminals 48 and 49 are still electrically connected to each other, the product is defective.

After that, a thin rod (not shown) is inserted into the hole 47a of the insulating frame 47, and the thin rod
The center of the disc spring 46 is pushed down, and the disc spring 46 is inverted again to return to the original state. As a result, each terminal 48,
If the 49's are electrically connected again, the safety device 41 is determined to be non-defective.

The present invention is not limited to the above embodiments, but can be variously modified.
For example, the outer shape of the safety device may be a quadrangular prism, and the internal parts may be quadrangular. Further, it is possible to change the shape and arrangement of each terminal. Furthermore, as welding,
Resistance welding, ultrasonic welding, laser welding, or the like can be applied, or screw welding, resin molding, or the like may be applied instead of welding. Connection, fixing, sealing, etc. may be performed. In short, the present invention is not limited by the selection and application of the processing method.

[0044]

As described above, according to the present invention, when the pressure in the battery case rises, the energization path is cut off to avoid an overcurrent or short circuit state, so that the pressure rise is suppressed and the battery case is prevented. The explosion of can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a secondary battery to which an embodiment of the safety device according to claim 1 is applied.

FIG. 2 is a sectional view showing the safety device of FIG.

FIG. 3 is a view used for explaining the operation of the safety device of FIG.

FIG. 4 is a view used for explaining the operation of the safety device of FIG.

FIG. 5 is a sectional view showing a secondary battery to which an embodiment of the safety device according to claim 2 is applied.

6 is a sectional view showing the safety device of FIG.

FIG. 7 is a view used to explain the operation of the safety device of FIG.

FIG. 8 is a sectional view showing an embodiment of the safety device according to claim 3;

9 is a view used for explaining the operation of the safety device in FIG.

[Explanation of symbols]

 1,21 Secondary battery 2,22 Power generating element 3,23 Battery case 4,27 Insulator 5,25,41 Safety device 6,28,42 Conductor case 7 Gasket 8,29 Aluminum foil 9,42a Cylindrical body 10 Spacer 11 , 46 Disc spring 12a PTC plate 12b Annular terminal 13 Insulation seal 14, 31, 45 Moving piece 15, 34 Contact piece 16, 26 Electrode lid 17, 35, 37, 48, 49 Terminal 18, 36, 38, 39, 50, 51,52 Lead wire 32,47 Insulation frame 33 Conductive support 43 Bellows container

Claims (5)

[Claims] 1. A sealing sheet which covers a hole of a battery case that hermetically seals a power generation element, and a surface of which faces the inside of the battery case through the hole, and is arranged on the back surface side of the sealing sheet. A battery safety device comprising a disc spring that is inverted by receiving the internal pressure of the battery case through the sealing sheet, and a switch unit that is arranged on the back side of the disc spring and that switches in conjunction with the reversal of the disc spring. 2. A sealing sheet which covers a hole of a battery case that hermetically seals a power generating element, and a surface of which faces the inside of the battery case through the hole, and a moving piece which is superposed on the back surface of the sealing sheet. A battery safety device comprising: a sealing member that expands toward the outside of the battery case due to the internal pressure of the battery case and the moving piece moves; and a switch means that switches in conjunction with the movement of the moving piece. 3. An expandable and contractible bellows container that covers a hole of a battery case that hermetically seals a power generating element and projects inside the battery case; and a movable piece arranged in the bellows container. When the disc spring is overlaid on this moving piece and expands toward the inside of the battery case, and when the disc spring expands toward the inside of the battery case, the disc spring comes into contact with the bellows container due to the internal pressure of the battery. When contracted, the moving piece moves to press the disc spring,
A battery safety device comprising a pair of terminals, at least one of which is separated from the disc spring when the disc spring is reversed. 4. The battery safety device according to claim 1, further comprising a positive temperature coefficient thermistor, wherein the positive temperature coefficient thermistor is inserted in a current-carrying path of the battery. 5. The battery safety according to claim 1, further comprising a hole communicating from the inside to the outside of the battery case, the hole is closed by a thin film, and the thin film is broken by pressure in the battery case. apparatus.