JPH11111244A - Sealed storage battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a safety valve that can control an operating pressure to break a thin portion by adjusting thickness and length of the thin portion formed inside an exterior can. SOLUTION: This sealed storage battery comprises an exterior can 10 of a cylindrical shape with a bottom, a generating element (electrode body) arranged inside the exterior can 10, and a sealing lid 30 that seals an opening part of the exterior can 10. A thin portion 11 is provided at a caulking part with the sealing lid 30 near the upper opening part of the exterior can 10. The generating element is contained in thus formed exterior can 10, and then the sealing lid 30 is arranged at the opening of the exterior can 10 through an insulating gasket 40 to assemble a nickel-cadmium storage battery by caulking an end edge of the opening of the exterior can 10 toward inside of it to seal the battery. Thereby, if a gas pressure inside the battery increases, the thin portion 11 deforms or is broken to release the gas to outside the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a battery case comprising a bottomed cylindrical outer can and a sealing lid having a safety valve while closing an opening of the outer can. The present invention relates to a sealed storage battery in which a battery element is housed and the upper part of an outer can is caulked and sealed with a sealing lid, and more particularly to an improvement in the safety valve structure.

[0002]

2. Description of the Related Art Generally, nickel-cadmium storage batteries,
A sealed storage battery such as a nickel-hydride storage battery generates a large amount of gas inside the battery when overcharged or overdischarged. Therefore, this type of sealed storage battery is provided with a gas discharge valve (safety valve) for discharging the gas out of the battery when the internal pressure of the battery rises abnormally due to the generation of gas. The gas discharge valve is generally of a return type that discharges gas to the outside of the battery when the inside of the battery reaches a predetermined pressure, and then closes when the gas pressure decreases. As the return type gas discharge valve, there are a method of urging the elastic valve element disposed on the upper surface of the gas vent hole with a spring and a method of urging the gas vent hole with a rubber elastic valve.

By the way, this kind of gas discharge valve 6 is shown in FIG.
As shown in the figure, the opening of the outer can 1 is disposed between the lid 4 of the sealing lid 3 and the positive electrode cap 5 which are hermetically sealed via the insulating gasket 2, and gas is generated at the time of overcharging or overdischarging. Then, the gas discharge valve 6 is pushed upward, and through the gas vent hole 4 a provided in the lid 4, the positive electrode cap 5
Is configured to be discharged out of the battery through an exhaust hole 5a provided at the bottom of the battery.

[0004] The battery provided with the gas discharge valve 6 operates at a constant pressure when the internal pressure of the battery increases.
Operates to discharge the gas inside the battery to the outside of the battery. However, when the battery is used in an abnormal state such as overcharge or overdischarge, the internal pressure of the battery rises and the inside of the battery is overheated at the same time, and organic polymers such as separators built in the battery are used. In some cases, the hot melt may melt, and this melt may block the gas vent hole 4a and the exhaust hole 5a, and the gas in the battery may not be discharged, which may impair safety.

To solve this problem, a thin-walled safety valve having a structure in which a thin-walled portion is provided in a part of an outer can of a cylindrical battery sealed by a hermetic seal, and the thin-walled portion is destroyed when the internal pressure of the battery increases, is disclosed in US Pat. No. 4,175,1
No.66 has been proposed. FIG.
(Note that FIG. 6A is a front view of the outer can, and FIG.
(B) is a view showing a half portion of the AA cross section), as shown in FIG. 3, the outer can 7 is formed into a square shape, and a thin portion is formed by thinning a part of the ridge other than the sealing portion of the outer can 7 It is possible to provide a thin break safety valve 8 having a structure in which the thin portion 8 is broken when the internal pressure of the battery rises.
No. 09 gazette.

[0006]

However, in the thin-wall fracture safety valve having the structure proposed in U.S. Pat. No. 4,175,166, the deformation of the thin-wall portion is small when the pressure in the battery is increased. It is difficult to accurately control the operating pressure of the battery, and the internal pressure of the battery rises abnormally, causing a problem of lack of reliability. On the other hand, in the thin-wall fracture safety valve having the structure proposed in Japanese Utility Model Laid-Open No. 5-90809, a thin-wall fracture safety valve is provided on the ridge of the outer can. Since it is difficult to form the fuel cell uniformly, the operating pressure of the safety valve of each battery varies, which also causes a problem that it is difficult to accurately control the operating pressure of the safety valve, resulting in a lack of reliability. In view of the above, the present invention has been made in view of the above problems, and a thin portion is easily formed by forming a thin portion at an appropriate position of an outer can and adjusting the thickness and length of the thin portion. It is an object of the present invention to obtain a safety valve capable of controlling the operating pressure to be applied.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a battery case comprising a bottomed cylindrical outer can and a sealing lid which closes an opening of the outer can and has a safety valve. A sealed storage battery containing at least a power generating element composed of a positive / negative electrode plate and sealing the upper part of the outer can by caulking with a sealing lid. It is characterized in that it is provided with a thin portion in which the thickness of a portion to be caulked is formed thinner than the thickness of the other portion.

As described above, the thin portion formed on the outer can is formed as a portion for caulking the sealing lid, and by adjusting the thickness of the thin portion or the length of the thin portion, the operating pressure at which the thin portion is easily broken can be reduced. Since the pressure can be controlled, the pressure at which the gas generated in the battery due to the deformation or breakage of the thin portion due to the increase of the battery internal pressure is released to the outside of the battery is small.

The thin portion is deformed and broken by the gas pressure generated in the battery when the safety valve does not operate normally, so that the safety valve and the thin portion provide double safety. And the gas generated in the battery can be reliably discharged to the outside of the battery. In addition, by setting the gas pressure at which the thin portion is deformed and destroyed to be higher than the gas pressure at which the safety valve normally operates, it is possible to reliably prevent the internal pressure of the battery from increasing even if the safety valve does not operate for some reason.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the present invention using nickel-
FIG. 2 is a diagram schematically illustrating an outer can of the sealed storage battery according to the present embodiment applied to a cadmium storage battery. FIG. 2 is a diagram illustrating a state in which a sealing lid is attached to the outer can of FIG. 1 and sealed, and FIG. It is a figure which shows the state in which the battery internal pressure rose and the thin part was destroyed. The nickel-cadmium storage battery according to the present embodiment includes a bottomed cylindrical outer can 10 in which nickel is plated on iron,
A power generation element (electrode body) 20 disposed in the outer can 10
And a lid 30 for sealing the opening of the outer can 10.

A thin portion 11 is provided in a portion of the cylindrical outer can 10 which is caulked with the sealing lid 30 near the upper opening 10a. Here, the outer diameter of the outer can 10 is 22 mm, the height is 44 mm, the thickness is 0.4 mm, the length of the thin portion 11 is 10 mm from the upper end of the opening 10a, and the thickness is 0.1 mm. It is formed by processing. The thin portion 11 may be thinner on the inside of the outer can 10 or thinner on the outer side of the outer can 10. The number of the thin portions 11 is not limited to two, and may be appropriately provided.

The power generation element 20 (see FIG. 3) is housed in the outer can 10 thus formed. The power generation element 20
The same as the sintered nickel positive electrode manufactured by forming a nickel sintered porous body on the surface of a punching metal and then filling the sintered porous body with a positive electrode active material mainly composed of nickel hydroxide by a chemical impregnation method. And a sintered cadmium negative electrode manufactured by filling a negative electrode active material mainly composed of cadmium hydroxide into a nickel sintered porous body by a chemical impregnation method, and the nickel positive electrode and the cadmium negative electrode are separated by a separator. It is wound with intervening.

Next, after a negative electrode current collector (not shown) welded to the cadmium negative electrode is spot-welded (not shown) to the inner bottom surface of the outer can 10, a positive electrode current collector lead extending from the positive electrode current collector is provided. The vicinity of the tip of the plate is spot-welded to the bottom surface of the sealing lid 30. After welding the positive electrode current collecting lead plate and the sealing lid 30 in this manner, the sealing lid 30 is disposed in the opening 10a of the outer can 10 via the insulating gasket 40, and the opening edge of the outer can 10 is caulked inward. Then, the battery is sealed and a nickel-cadmium storage battery is assembled. Thereby, as shown in FIG. 2, the thin portion 11 comes to be folded on the upper surface of the sealing lid 30.

Here, the sealing lid 30 includes a lid 31 having a circular downward protruding portion formed on the bottom surface, a positive electrode cap 32, a spring and a valve plate interposed between the lid 31 and the positive electrode cap 32. A gas vent hole 34 is formed in the center of the lid 31. An exhaust hole 35 is formed in the bottom of the positive electrode cap 32.

Next, the exhaust operation of the nickel-cadmium storage battery of this embodiment will be described. First, the exhaust hole 3
When the valve body 33 operates normally with the valve 5 not closed, gas is generated inside the battery due to overcharging or overdischarging, and the gas pressure inside the battery increases to a predetermined gas pressure (for example, When the pressure reaches 20 kgf / cm ² ), the valve body 33 is pushed upward by this gas pressure.
Then, gas flows into the sealing lid 30 from the gas vent hole 34 of the sealing lid 30.

The gas flowing into the sealing lid 30 is
Through the exhaust hole 35 provided at the bottom of the battery. When the gas generated in the battery is released to the outside of the battery and the pressure in the battery decreases, the valve body 33 closes the gas vent hole 34 by its urging force, so that the inside of the battery is closed again.

Here, for some reason, the valve body 33 does not operate normally, or the exhaust hole 35 is closed, and the gas pressure inside the battery rises to a pressure higher than the predetermined gas pressure (for example, When the pressure reaches 50 kgf / cm ² ), the pressure causes the thin portion 11 provided on the outer can to be deformed or broken, and as shown in FIG. Will be released. Therefore, the battery can be prevented from being ruptured due to an abnormal increase in battery internal pressure, and the safety of the battery can be ensured.

Modification In the above embodiment, the present invention has been described with reference to a cylindrical storage battery. However, the present invention can be applied to a rectangular storage battery. FIG. 4 is a view showing a state in which a sealing lid is attached to a rectangular outer can of this modification in which the present invention is applied to a rectangular storage battery, and the rectangular outer can is sealed. The prismatic nickel-cadmium storage battery according to the present modified example includes a bottomed rectangular cylindrical outer can 50 in which iron is plated with nickel, a power generation element (electrode body) disposed in the outer can 50, and an outer can 50. And a sealing lid 70 for hermetically closing the opening.

A thin-walled portion 51 is provided in a portion of the bottomed rectangular cylindrical outer can 50 that is caulked with the sealing lid 70 near the upper opening. Here, the outer dimension of the outer can 50 is 16
mm, the depth is 8 mm, the height is 40 mm, the thickness is 0.25 mm, the length of the thin portion 51 is 10 mm from the upper end of the opening, and the thickness is formed to be 0.1 mm. doing. The thin portion 51 may be thinner on the inside of the outer can 50 or thinner on the outer side of the outer can 50. The number of the thin portions 51 is not limited to one, and may be appropriately provided.

A power generating element (electrode body) is housed in the outer can 10 formed as described above. The electrode body is formed by forming a nickel sintered porous body on the surface of an electrode core made of punched metal, and then filling the nickel sintered porous body with an active material mainly composed of nickel hydroxide by a chemical impregnation method. A sintered nickel positive electrode plate, and a sintered cadmium negative electrode plate similarly manufactured by filling an active material mainly composed of cadmium hydroxide into the nickel sintered porous body by a chemical impregnation method. The positive electrode plate is included in the separator, and the nickel positive electrode plate and the cadmium negative electrode plate included in the separator are alternately laminated to form an electrode body. Note that a cadmium negative electrode plate is disposed at both ends of the electrode body.

Next, after the cadmium negative electrode is electrically connected to the inner surface of the outer can 50, the vicinity of the front end of the positive current collector lead plate extending from the positive current collector is spot-welded to the bottom surface of the sealing lid 70. After welding the positive electrode current collecting lead plate and the sealing lid 70 in this manner, the sealing lid 70 is attached to the opening of the outer can 50 via the insulating gasket 80, and the opening edge of the outer can 50 is crimped inward. Thus, the battery is sealed and a prismatic nickel-cadmium storage battery is assembled. Thereby, as shown in FIG. 4, the thin portion 51 is folded on the upper surface of the sealing lid 70.

Here, similarly to the sealing lid 30 of the above embodiment, the sealing lid 70 has a lid 71 having a downwardly projecting portion formed on the bottom surface, a positive electrode cap 72, and a gap between the lid 71 and the positive electrode cap 72. And a valve body (not shown) composed of a valve plate, and a gas vent hole (not shown) is formed in the center of the lid 71. An exhaust hole (not shown) is formed at the bottom of the positive electrode cap 72. Note that the exhaust operation of the prismatic nickel-cadmium storage battery of the present modified example is the same as the exhaust operation of the cylindrical nickel-cadmium storage battery of the above-described embodiment, and thus detailed description thereof will be omitted. In addition,
In the prismatic nickel-cadmium storage battery according to the present modification, the operating pressure of the valve disposed in the sealing lid 70 is 10 k.
gf / cm ² , and the thin portion 5 of the outer can 50
The working pressure of No. 1 is set to 30 kgf / cm ² .

Using ten rectangular nickel-cadmium storage batteries of the present modified example, these positive and negative terminals (positive cap 72
An overcharge test was conducted in which a charging current of 10 A was applied between the battery and the bottom of the outer can 50), and the number of destruction or deformation of the thin portion 51 when the internal pressure of the battery became 30 kgf / cm ² was observed. The result was as shown in the figure. On the other hand, as a nickel-cadmium storage battery of a comparative example, ten square nickel-cadmium storage batteries as shown in FIG.
An overcharge test was conducted in which a charging current of 10 A was applied between the positive and negative terminals of each of these ten square nickel-cadmium storage batteries, and the number of destruction or deformation of the thin portion 8 when the battery internal pressure reached 30 kgf / cm ² Table 1
The result was as shown in the figure. The overcharge test was performed with the safety valve closed and the safety valve not operating.

[0024]

[Table 1]

As is evident from Table 1, it is confirmed that the prismatic nickel-cadmium storage battery of the present modification has a larger number of destruction or deformation of the thin portion than the prismatic nickel-cadmium storage battery of the comparative example. .

As described above, in the present invention, since the thin portion 11 (51) is provided at a portion that is caulked to the sealing lid 30 (70), the thickness and length of the thin portion 11 (51) are adjusted. By doing so, the thin portion 11 (5
It becomes possible to control the operating pressure that destroys 1). For this reason, the thin portion 11
(51) is deformed or destroyed, and the gas generated in the battery is released outside the battery.

The thin portion 11 (51) is
If the safety valve disposed in (70) does not operate normally, it is deformed and broken by the gas pressure generated in the battery, so that the safety valve and the thin portion 11 (5)
With 1), safety can be provided twice, and gas generated in the battery can be reliably discharged to the outside of the battery. In addition, the gas pressure at which the thin portion 11 (51) is deformed and broken is made higher than the gas pressure at which the safety valve disposed in the sealing lid 30 (70) normally operates, so that the safety valve operates for some reason. Without this, an increase in battery internal pressure can be reliably prevented.

The nickel-cadmium storage batteries of the above-described embodiment and the modified example use sintered electrodes for both the positive electrode and the negative electrode. However, when experiments are performed using batteries using non-sintered electrodes such as a paste type. Also obtained similar results.

[Brief description of the drawings]

FIG. 1 is a view schematically showing an outer can of a sealed storage battery according to an embodiment of the present invention.

FIG. 2 is a view showing a state in which a sealing lid is attached to the outer can of FIG. 1 and hermetically sealed;

FIG. 3 is a diagram showing a state in which a thin portion is destroyed due to an increase in battery internal pressure.

FIG. 4 is a view showing a state in which a sealing lid is attached to an outer can of a modification and hermetically sealed.

FIG. 5 is a diagram showing a conventional sealed storage battery.

FIG. 6 is a diagram showing a sealed storage battery in which a thin portion is provided in a conventional outer can.

[Explanation of symbols]

10: exterior can (negative electrode external terminal), 11: thin part, 20:
Power generating element (electrode body), 30: sealing lid, 40: insulating gasket, 31: lid, 32: positive electrode cap (positive electrode external terminal), 33: valve, 34: gas vent hole, 35: exhaust hole,
50: outer can (negative electrode external terminal), 51: thin part, 70:
Sealing lid, 80 ... insulating gasket

Claims (3)

[Claims] 1. A power generation element comprising at least a positive and negative electrode plate is housed in a battery case comprising a bottomed cylindrical outer can and a sealing lid having a safety valve while closing an opening of the outer can. A sealed storage battery in which the upper part of the outer can is caulked and sealed to the sealing lid, and the thickness of a part of the part caulked to the sealing lid on the upper part of the outer can is made larger than the thickness of other parts. A sealed storage battery comprising a thin portion formed thinly. 2. The hermetic mold according to claim 1, wherein the thin portion is configured to be deformed and destroyed by gas pressure generated in the battery when the safety valve does not operate normally. Storage battery. 3. The sealed storage battery according to claim 1, wherein a gas pressure at which the thin portion is deformed and broken is higher than a gas pressure at which the safety valve operates normally.