JPH0636209U - Sealed battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a sealed battery that is equipped with a safety valve device with good pressure responsiveness, protects the terminal on the device side from corrosion of the electrolyte when the safety valve is activated, and has excellent leak resistance. . [Structure] A metal sealing lid has a gas vent, the gas vent is closed with a heat-sealing film, and a metal body having a cutting edge on a surface facing the heat-sealing film is installed on the metal sealing lid. However, this safety valve mechanism is not installed inside the unipolar terminal.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a sealed battery as a power source for driving a portable device, and more particularly to an explosion-proof and safety structure against a rise in battery internal pressure and a rise in battery temperature at the time of short circuit or overcharging / discharging.

[0002]

[Prior art]

 In recent years, large currents and large outputs are required for batteries as power sources, such as laptop computers, portable information devices such as word processors, camera-integrated VTRs, AV devices such as LCD TVs, mobile communication devices such as mobile phones, etc. There is a wide variety of developing devices and there is a demand for batteries with higher energy density. Furthermore, as equipment becomes thinner and smaller, batteries must be thinner and smaller.

Then, in order to meet the demand, various new batteries have been proposed.

However, in order for a battery to be used stably for a long period of time, a battery caused by a reaction with a battery active material, an electrolyte or the like due to leakage of an electrolytic solution or intrusion of moisture in the air into the battery In order to prevent deterioration of performance, it is necessary to completely seal the battery in terms of both airtightness and liquid-tightness, and the sealing is extremely high.

Conventionally, in this type of battery, as shown in FIG. 2, a metal sealing lid (21) is sandwiched between an insulating packing (22) and an insulating packing (23) to insulate a rivet (24) that also serves as a unipolar terminal. Insert the packing washer (25) into the through hole (25), insert the current collecting washer (26) from below, pressurize the whole in the vertical direction, and expand the rivet leg tips to open the lid (27). Then, the lid and the outer can (28) also serving as another polar terminal are welded by laser welding or the like.

Further, as shown in FIG. 3, a hermetic structure using an insulating member (33) such as a glass seal or a ceramic seal is adopted, and an outer can (31) also serving as a unipolar terminal and a metal sealing lid (32). A structure is employed in which the other polarity terminal pins (34) are fixed through the insulating member (33) while being welded together by laser welding or the like.

However, this type of battery is exposed to a high temperature, an external short circuit or an internal short circuit due to deterioration of electrodes or separators, a change in shape, or a forced overcurrent discharge by an external power source causes a rapid temperature rise. In addition, when the secondary battery is overcharged due to excessive voltage, the electrolytic solution volatilizes or decomposes to generate gas, and this gas is trapped inside the battery. Since the internal pressure rises significantly, the outer can of the battery expands and deforms, damages the equipment that contains the battery, and sometimes the battery bursts, which is a serious safety issue.

Therefore, in order to prevent the battery from exploding, as shown in FIG. 4, a part of the bottom of the outer can (41) is made thin so that the thin portion (42) will rise when the battery internal pressure rises abnormally. There are things that try to have a structure that breaks. However, in this case, it is difficult to control the thickness of the thin-walled portion, it is difficult to set the operating pressure, and sufficient safety cannot be obtained.

The battery structure of FIG. 5 is a main part of a battery structure in which a rubber valve body is used as a safety valve. The metal sealing lid (51) is sandwiched by the insulating packing (52) and the insulating packing (53) from above and below, and the hollow rivet (54) is inserted into the through hole (55) of the insulating packing. 56) is inserted, and the whole is vertically pressed to expand and crimp the tip of the leg of the hollow rivet. Next, the rubber valve body (57) is placed on the seat of the hollow rivet, and the terminal cap (58) and the seat of the hollow rivet are spot-welded while pressure is applied from above with the cap (58) also serving as a unipolar terminal. The lid body (59) is obtained as described above. This structure can be equipped with a safety valve with particularly good pressure response.

However, since the safety valve is provided inside the unipolar terminal, when the safety valve is activated, the terminal on the device side that is in contact with the unipolar terminal / cap is exposed to the electrolytic solution ejected from the battery. This causes the terminal to be corroded. Further, there is a problem in the leak resistance characteristic that a gap is easily formed between the rubber valve body and the seat of the hollow rivet, and the electrolyte leaks through the gap.

[0011]

[Problems to be solved by the device]

 Therefore, it is an issue to provide a sealed battery that is equipped with a safety valve device with good pressure responsiveness, protects the terminal side of the device from corrosion of the electrolytic solution when the safety valve is activated, and has excellent leak resistance.

[0012]

[Means for Solving the Problems]

 An object of the present invention is to obtain a sealed battery having a safety mechanism capable of preventing the outer can from swelling or bursting, and has a metal sealing lid with a gas vent, and the gas vent is heat-melted. It is characterized in that a metal body, which is closed by an adhesive film and has a cutting edge on the surface facing the heat-sealing film, is installed on a metal sealing lid, and that this safety valve mechanism is not installed side by side in a unipolar terminal. .

[0013]

[Action]

 According to the battery of the present invention, since it has a safety valve having a good pressure response shown in FIG. 1, the battery is not ruptured due to an abnormal condition such as misuse and is excellent in safety. In addition, since the safety valve is not installed inside the unipolar terminal, even if the electrolyte squirts out of the battery when the safety valve is activated, it does not corrode the terminal on the device side. Since the vent hole is closed, it has excellent leak resistance.

[0014]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view of a main part of a sealed battery according to an embodiment. In FIG. 1, (1) is an outer can that also serves as a unipolar terminal, in which a power generating element (not shown) is incorporated.

The outer can (1) is made of a material having excellent conductivity, such as iron, and is drawn into a square shape by a press or the like. The surface of the outer can (1) is usually plated with nickel.

Further, in the present embodiment, the outer dimensions of this outer can (1) were 6.4 mm in thickness, 22.2 mm in width, 77.5 mm in height, and 0.4 mm in plate thickness. (2) is a metal sealing lid having a gas vent hole (3), which is pressed with iron having a plate thickness of 0.4 mm, is inserted inside the outer can (1), and is welded by laser welding. ing. Further, the gas vent hole (3) is closed by a heat sealing film (4). A metal body (5) having a cutting edge on the surface facing the heat-sealing film (4) is installed on the metal sealing lid by resistance welding. At this time, the distance between the tip of the cutting blade and the heat-sealing film was 0.20 mm. (6) is a rivet which also serves as a polar terminal. The metal sealing lid (2) is sandwiched between the insulating packing (7) and the insulating packing (8), and inserted into the through hole (9) of the insulating packing, and is collected from the bottom. An electric washer (10) is inserted, and the whole is vertically pressed to expand and crimp the rivet (6) leg tip. The material of the rivet (6), which also functions as the other polarity terminal, was stainless steel, the material of the current washer (10) was aluminum, and the insulating packings (7) and (8) were polypropylene resin.

Next, the relationship between the thickness of the heat-sealing film and the size of the gas vent hole was changed and the crack release pressure of the heat-sealing film was investigated. In this example, a polypropylene resin was used as the heat-sealing film, and the polypropylene resin was heat-sealed for adhesion to the metal sealing lid. The method for measuring the crack opening pressure of this heat-sealing film is shown below.

First, a rivet (6) also serving as a single-polarity terminal, an insulating packing (7), an insulating packing (8), a washer (10) for collecting electricity, and a heat-sealing film (4) without incorporating a power-generating element. After laser-welding the metal sealing lid (2) having the metal body (5) equipped with a cutting edge and the empty outer can (1), a thin copper tube is brazed with silver on the side of the outer can. Nitrogen gas was injected into the inside, and the pressure when the heat-sealing film was torn open was measured.

Table 1 shows the tear release pressure of the heat-sealing film when the diameter of the gas vent hole and the thickness of the heat-sealing film were changed in the examples of the present invention.

[0021]

[Table 1] From Table 1, when the diameter of the gas vent is 1.0 mm, the film thickness is 0.08 mm, and when the diameter of the gas vent is 1.5 mm, the film thickness is 0.120 mm to 0.150 mm. As a result, a safety valve that releases the cut at an appropriate working pressure was obtained.

As a comparative example, as shown in FIG. 5, in a conventional sealed battery, a thin copper tube was brazed with silver on the side surface of an outer can in which no power-generating element was incorporated, and nitrogen was applied to the inside, as in the case of the example. When gas was injected and the pressure at the time of breaking was measured, when the pressure reached 51.3 kg / cm ² , a laser welded portion between the outer can and the metal sealing lid was cracked and ruptured.

In this embodiment, polypropylene resin is used as the material of the heat-sealing film, but polyethylene resin may be used.

Further, in the present embodiment, the distance between the heat-sealing film and the tip of the cutting blade is set to 0.2 mm, but the tear release pressure of the heat-sealing film changes depending on the set value of this distance. That is, when the internal pressure of the battery rises, the heat-sealing film bends and the film is torn when it hits the tip of the cutting blade.However, the deflection amount of the film increases as the distance between the film and the tip of the cutting blade increases. It is necessary, and the pressure that causes the deflection must be increased, which causes a problem that the dissection pressure varies. Further, if the distance between the film and the tip of the cutting blade is too short, the film may be damaged by the cutting blade during manufacturing. With 0.2 mm shown in this example, there was no fluctuation in the cleavage release pressure, and good results were obtained without damaging the film even during battery production.

The film thickness also largely depends on the tear release pressure, but if the film is too thin, moisture in the atmosphere permeates this film and enters the inside of the battery, leading to deterioration of battery performance. It cannot be thinned. As shown in this example, when the film thickness is 0.08 mm or more, the permeation of moisture in the atmosphere is suppressed, and the battery performance is not deteriorated.

Further, in the sealing lid used in this embodiment, the metal sealing lid (2) is sandwiched between the insulating packing (7) and the insulating packing (8), and the rivet (5) also serving as another polar terminal is insulated. Insert into the through hole (9), insert the washer (10) for current collection from below, press the whole in the vertical direction, and use the one with the tip of the rivet (6) expanded and crimped. However, it may be adopted in a hermetic structure in which the other polar terminal is fixed through the through hole of the metal sealing lid by an insulating member such as glass or ceramic seal.

[0027]

[Effect of device]

 As is clear from the above explanation, according to the battery of the present invention, when the internal pressure of the battery rises, the heat-sealing film tears and the gas inside the battery is released to the outside, so there is no risk of the battery bursting. Excellent in safety. In addition, since it is not installed inside the unipolar terminal, even if the electrolyte squirts out of the battery when the safety valve is activated, it does not corrode the terminal on the device side. Since it closes the holes, it has excellent leak resistance and its industrial value is extremely large.

[Brief description of drawings]

FIG. 1 is a sectional view of a main part of a sealed battery according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a conventional sealed battery.

FIG. 3 is a cross-sectional view of a main part of a conventional sealed battery

FIG. 4 is a sectional view of a main part of a conventional sealed battery.

FIG. 5 is a sectional view of a main part of a conventional sealed battery.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Exterior can 2 Metal sealing lid 3 Gas venting hole 4 Heat sealing film 5 Metal body with cutting blade 6 Rivets that also serve as other polar terminals 7 Insulating packing 8 Insulating packing 9 Through hole 10 Current collecting washer 21 Metal sealing lid 22 Insulation Packing 23 Insulating packing 24 Rivets that also serve as one polarity terminal 25 Through hole 26 Washer for current collection 27 Lid body 28 Outer can 31 Outer can for one polarity terminal 32 Metal sealing lid 33 Insulation member 34 Other polarity terminal pin 41 Outer can 42 Thin portion 51 Metal sealing lid 52 Insulation packing 53 Insulation packing 54 Hollow rivet 55 Through hole 56 Current collecting washer 57 Rubber valve body 58 Terminal cap 59 Lid body 60 Other polar terminal and outer can

Claims (1)

[Scope of utility model registration request] 1. An outer can (1) and a metal sealing lid (2), wherein the outer can (1) contains a power-generating element and doubles as a unipolar terminal, and the metal sealing lid (2) is the outer can. A metal sealing lid which is welded and conductively fixed to the opening of (1), and has another polar terminal fixed to the through hole formed in the metal sealing lid (2) through an insulating member. A gas vent hole (3) is provided in the lid (2), and
The gas vent hole (3) is located in the gap between the other polarity terminal and the side end of the metal sealing lid, and the gas vent hole (3) is always closed by the heat sealing film (4). A sealed battery, wherein a metal body (5) having a cutting edge on a surface facing (4) is installed on a metal sealing lid (2).