JPH07226196A - Battery explosion-proof device - Google Patents

Abstract

PURPOSE:To actuate a device in a comparatively low pressure area with simple constitution to flow a charging-discharging current by coating an electrode terminal with an electric conductor cutoff plate deformed by a cleavage of a cleavage film by an increase in internal pressure as well as to fix the end part to an airtight wall. CONSTITUTION:A small hole 36 formed in a prescribed position of an upper surface 35a of an enclosing can 35 on which a positive electrode terminal 32 of a battery 30 is arranged, is coated with a cleavage film 31, and sealing in the battery 30 is kept. The sides of a cutoff plate 33 are adhered and fixed to side walls 34a and 34b of an airtight box body 34 composed of an insulating material sealed and fixed to an upper surface of the battery 30, and a sealed space 37 is formed, and an exhaust hole 38 is arranged on a side wall above the cutoff plate 33. The cutoff plate 33 is composed of flexible conductor foil, and is connected to the terminal 32 by resistance welding or the like, and since one end is connected to an external electrode terminal 39 by an aluminium lead 40, a charging-discharging current is flowed. In such constitution, since an electric current is cut off by a comparatively low pressure increase in the battery, a temperature rise by overcharge or the like is restrained in its early stages.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery explosion-proof device suitable for use in sealed secondary batteries such as lithium batteries and carbon lithium batteries.

[0002]

2. Description of the Related Art Generally, in a sealed type secondary battery such as a lithium battery or a carbon lithium battery, there is a problem that the outer can is remarkably deformed due to an increase in pressure under a high temperature condition and ruptured in an abnormal condition such as overcharge.

Therefore, conventionally, an explosion-proof device as shown in FIG. 4, for example, has been provided in order to prevent the above-mentioned pressure rise and rupture of the battery. As shown in FIG. 4, a battery provided with this conventional explosion-proof device has a cylindrical outer can 1 in which a power generating element is housed, a gasket 2 provided on the inner periphery of the upper end of the outer can 1, and this gasket. 2, an explosion-proof valve 3 also serving as an intermediate casing press-fitted and supported, a stripper 4 installed in contact with the lower surface of the explosion-proof valve 3, and a closing lid 5 for closing the outer can 1. The gasket 2, the explosion-proof valve 3, and the closing lid 5 are caulked and attached to the outer can 1.

In the outer can 1, a negative electrode material (for example, a metallic lithium foil) and a positive electrode material (for example, a positive electrode substrate coated with molybdenum sulfide) are sandwiched with a separator in which an electrolytic solution is impregnated, and placed on a core 21. A power generator 6 formed by winding in a tubular shape is housed as a power generating element, and a sheet-shaped insulating plate 7 is formed on the upper portion of the power generator 6. An insertion hole 10 for inserting a lead terminal 9 extending from the lead plate 8 is formed at the center of the insulating plate 7.

The lead terminal 9 is attached to a positive electrode material which is bent from the lead plate 8 and wound in a tubular shape. The lead plate 8 is connected to a lower surface of a projection 3a of the explosion-proof valve 3 described below facing downward from an insertion hole 11 of the stripper 4 by a method such as ultrasonic welding. At this time, the lead plate 8 is
The state is such that the lower surface of the stripper 4 and the projection 3a of the explosion-proof valve 3 are bridged.

An explosion-proof valve 3 is provided on the upper surface of the gasket 2. The explosion-proof valve 3 is made of aluminum, nickel or an alloy thereof, and is inserted inside the rising portion 13 provided on the gasket 2. Further, the explosion-proof valve 3 has a step portion 14 slightly inward of the inside of the gasket 2, and a protruding portion 3b protruding downward from a portion hanging down from the step portion 14. Further, it has a protrusion 3a protruding downward from the raised portion 3b in the central portion, and further, between the raised portion 3b and the protrusion 3a, a thin wall formed on the upper surface thereof by a radial groove from the vicinity of the root of the protrusion 3a. It has a part 15.

The stripper 4 installed below the explosion-proof valve 3 is made of an insulating material such as plastic and has an insertion hole 11 into the center of which the projection 3a of the explosion-proof valve 3 is inserted. The conductive film 16 is deposited. When the protrusion 3a of the explosion-proof valve 3 is inserted into the insertion hole 11, the conductive film 16 contacts the lower part of the root of the protrusion 3a and the lower surface of the raised part 3b.

The lower surface of the stripper 4 and the projection 3a
The lead plate 8 is welded to the lower surface of the protrusion 3a so as to bridge the lower surface of the protrusion 3a. Furthermore, the outside of the step portion of the explosion-proof valve 3 is the flat portion 3
c, and the surface of the flat portion 3c and the closing lid 5
The flat terminals contact each other to electrically connect the lead terminal 9, the lead plate 8, the explosion-proof valve 3 and the closing lid 5.

According to the configuration of FIG. 4 described above, for example, when the overcharged state progresses, a gas is generated and filled by the chemical reaction of the power generating element, and the pressure in the battery starts to rise due to the filling of the gas. Explosion-proof valve 3 is deformed by rising, and explosion-proof valve 3
The protrusion 3a is pressed in the pressure direction, that is, in the direction of the closing lid 5, and moves upward. That is, the upward movement of the protrusion 3a causes the lead plate 8 welded to the lower surface of the protrusion 3a to peel or break at this welded portion,
When the pressure is released and the charging current is cut off, it is possible to prevent the battery from igniting and bursting.

[0010]

However, as shown in FIG. 4, in the conventional battery explosion-proof device, the explosion-proof valve 3 is crimped to the outer can 1, and against the pressure of the explosion-proof valve 3 that can be stored in the outer can 1. The area of the surface will be limited. Since this area determines the pressure when the explosion-proof valve 3 is opened, for example, when the surface area of the outer can 1 against the pressure becomes small, the surface area of the explosion-proof valve 3 that can be housed in the outer can 1 with respect to the pressure similarly. The pressure becomes smaller, and a larger pressure is required to deform the explosion-proof valve 3 in the pressure direction to break the current and cut off the current.

For example, in the case of a prismatic sealed battery or the like, the area of the explosion-proof valve 3 that can be housed in a quadrangle due to its geometrical restrictions is the same as the area of the quadrangle of the rectangular parallelepiped outer can. The area is smaller than the area of the explosion-proof valve 3 that can be housed in a cylindrical outer can, and the pressure for cleaving increases.

Further, due to the mechanical effect based on the geometrical characteristics, the pressure increases until the explosion-proof valve 3 is opened, and the deformation of the outer can in the pressure direction easily progresses. For this reason, not only the appearance of the battery is impaired, but also in the equipment used, the battery cannot be taken out.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a battery explosion-proof device which has a simple structure and can be operated in a relatively low pressure region.

[0014]

The battery explosion-proof device of the present invention is, for example, as shown in FIGS. 1 and 2, a cleavage film 31 that is cleaved by an increase in the internal pressure of the battery 30, and a pressure released by the cleavage of the cleavage film 31. And an airtight wall 34 to which an end portion of the blocking plate 33 is fixed, the blocking plate 33 being made of a conductive material and attached to the electrode terminal 32 of the battery 30. The charging / discharging battery of the battery 30 is caused to flow through the blocking plate 33, and when the internal pressure of the battery 30 reaches a predetermined pressure, the cleavage film 31 is split and the blocking plate 33 is deformed by this pressure. The blocking plate 33 is peeled off from the electrode terminal 32 to interrupt the current and release the internal pressure of the battery 30.

[0015]

According to the present invention, when the pressure in the battery 30 begins to rise due to overcharge or short circuit, the cleavage film 31 is cleaved in the pressure direction and the space surrounded by the blocking plate 33 and the airtight wall 34 is formed. 2 increases, the blocking plate 33 is deformed in the pressure direction as shown in FIG. 2, and the blocking plate 33 is separated from the electrode terminal 32 or the blocking plate 33 breaks to block the current and release the internal pressure.

That is, by suppressing the temperature rise due to overcharge or short circuit current of the battery 30 in the initial stage, the battery 30
By suppressing the smoke generation, ignition and rupture, and by making the area of the blocking plate 33 sufficiently large, the current breaking pressure is reduced, and the deformation of the outer can 35 due to the pressure increase can be prevented in the low pressure region.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the battery explosion-proof device of the present invention will be described below with reference to the drawings. In FIGS. 1 and 2, reference numeral 30 denotes a battery composed of, for example, an 8 mm × 34 mm × 48 mm prismatic lithium-ion battery (700 mAh), and the battery 3 is provided at the center of an upper surface 35 a of an outer can 35 of the battery 30.
Although not shown, the negative electrode terminal 32 is provided on the lower surface of the outer can 35 of the battery 30.

In this example, the upper surface 35 of the battery 30
A small hole 36 having a diameter of 2.5 mm is formed at a predetermined position of a, and a soft copper foil having a thickness of, for example, 10 μm is used as a cleavage film 31 in the small hole 36 by a method such as laser welding to deposit the battery 30.
Make sure the inside is kept sealed.

Further, in the present embodiment, the airtight box 34, which has the same bottom shape as the upper surface 35a and is made of an insulating material such as synthetic resin, is hermetically fixed on the upper surface of the battery 30.

One side of the rectangular blocking plate 33 facing each other is adhered and fixed to the side walls 34a and 34b of the airtight box 34 facing each other, and the other side of the blocking plate 33 is freely moved. Do as you can. In this case, the upper surface 35a of the battery 30 and the blocking plate 33
The side wall of the airtight box 34 forms a closed space 37.

As the blocking plate 33, 6 mm × 34 mm
Made of iron, aluminum, nickel, or an alloy thereof, and made of a flexible conductor foil, and the central portion of the blocking plate 33 is connected to the positive electrode terminal 32 of the battery 30 by a technique such as resistance welding. I will do it.

An exhaust hole 38 is formed at a predetermined position above one or the other blocking plate 33 of the other side wall of the airtight box 34, and an external electrode terminal 39 is provided on the upper surface of the airtight box 34. . The external electrode terminal 39 is electrically connected to the blocking plate 33 via the aluminum lead 40. In this case, the external electrode terminal 39 is electrically connected to the positive electrode terminal 32 of the battery 30 via the aluminum lead 40 and the blocking plate 33. In this case, the charging / discharging current of the battery 30 is made to flow through the external electrode terminal 39.

In the present example constructed as described above, 20
As a result of performing an overcharge test with V and 2A, it was as shown in FIG. 2 and FIG. That is, as the charging progresses, the battery voltage rises as shown in the curve a as shown in FIG. 3, and the battery temperature rises as shown in the curve b as well.

Therefore, the pressure inside the outer can 35 rises as shown by the curve c, the cleavage film 31 is cleaved, and the pressure in the airtight space 37 surrounded by the blocking plate 33 and the side wall of the airtight box 34 rises. As the pressure increases, as shown in FIG.
The connection portion between the blocking plate 33 and the electrode terminal 32 is pressed in the pressure direction, that is, in the direction opposite to the battery 30, and moves upward.

By the upward movement of this connecting portion, the blocking plate 33 is broken at this connecting portion, the charging current is blocked as shown by the curve c, and this blocking plate 33 moves to the position of the exhaust hole 38. By exhausting the gas in the airtight space 37, the pressure in the outer can 35 is released.

In FIG. 3, the breaking point of the charging current is formed after the cleavage of the cleavage film 31, and then the temperature in the battery 30 is lowered to prevent abnormalities such as ignition and rupture of the battery 30.

As described above, according to this example, the blocking plate 33
As compared with the conventional battery explosion-proof device, the pressure inside the outer can 35 can be released and the current can be interrupted before the low pressure, that is, the deformation of the outer can 35 becomes significant. It is possible to prevent ignition and explosion.

Even if an external short circuit occurs due to the misuse of the battery 30, this function and effect suppress the temperature rise due to the short circuit current and the accompanying pressure rise in the outer can 35 at the initial stage, and the outer can 35 is significantly deformed. It is possible to prevent the battery itself from catching fire and bursting.

When the pressure in the outer can 35 of the battery 30 rises due to the battery 30 being left at a high temperature, the cleavage pressure of the cleavage film 31 shown in FIG. The pressure will be released into the atmosphere.

The present invention is not limited to the above-described embodiment, but a projection may be formed in the central portion of the blocking plate 33 and the projection may be welded to the electrode terminal 32. Further, the present invention is not limited to the above-described embodiments, and it goes without saying that various other configurations can be adopted without departing from the gist of the present invention.

[0031]

According to the present invention, by suppressing the temperature rise due to overcharge or short circuit current of the battery in the initial stage,
By suppressing smoke, ignition, and rupture of the battery and by making the area of the blocking plate sufficiently large, there is an advantage that the current breaking pressure is reduced and the deformation of the outer can due to the pressure increase can be prevented in a low pressure region.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of a battery explosion-proof device of the present invention.

FIG. 2 is a sectional view showing an example of a main part of the present invention.

FIG. 3 is a diagram for explaining the present invention.

FIG. 4 is a cross-sectional view showing an example of a conventional battery explosion-proof device.

[Explanation of symbols]

 30 Battery 31 Cleavage Membrane 32 Electrode Terminal 33 Blocking Plate 34 Airtight Box 35 Exterior Can 36 Small Hole 37 Airtight Space 38 Exhaust Hole 39 External Electrode Terminal 40 Aluminum Lead

Claims (1)

[Claims] 1. A cleaving film that cleaves when the internal pressure of the battery rises, and a conductor that is deformed in the pressure direction by the pressure released by the cleaving of the cleaving film and is attached to the electrode terminal of the battery. A blocking plate and an airtight wall to which an end of the blocking plate is fixed, the charging and discharging current of the battery is made to flow through the blocking plate, and when the internal pressure of the battery reaches a predetermined pressure, A battery explosion-proof device, characterized in that the cleaving film is cleaved, the blocking plate is deformed by pressure, the blocking plate is peeled off from the electrode terminal to block the current, and the internal pressure of the battery is released. .