JP2574427Y2 - Battery safety device - Google Patents

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 applied to a cylindrical lithium battery or the like, and more particularly, to a safety device for preventing a battery from exploding or ignited even in the case of misuse or any accident. Regarding improvement.

[0002]

2. Description of the Related Art A lithium battery, particularly a spiral lithium battery in which a positive electrode and a negative electrode are spirally wound with a separator interposed therebetween, has a feature that a large load current can be taken out. On the other hand, the battery heats up due to misuse or unexpected trouble of the equipment used, resulting in an abnormally high temperature, and the pressure inside the battery case may become abnormally high, causing an explosion or ignition. Therefore, various countermeasures have conventionally been taken to enhance the safety of the lithium battery even if there is a misuse or trouble in the equipment used.

For example, JP-A-2-112151 discloses the following battery safety device. That is, a spiral-type lithium battery in which a spiral-type power generating element of a lithium battery is housed in a bottomed cylindrical metal battery case, and a lid member is attached to an open end of the battery case via a plastic sealing gasket. In
A safety device is incorporated in the lid member or the inner bottom of the battery case. This safety device has both the function of a pressure-sensitive switch that shuts off the internal current of the battery when the internal pressure of the battery increases, and the function of a safety valve that releases gas in the battery to the outside when the internal pressure of the battery further increases. That is, when the safety device is incorporated in the lid member, the lid member incorporates a diaphragm that deforms so as to expand outward as the battery internal pressure increases, and when the amount of deformation of the diaphragm increases to some extent, A lead plate connecting one pole of the power generating element and the terminal plate of the lid member is broken to cut off a current path, and a thin portion of the diaphragm is cut to release gas inside the battery. I have. When the safety device is provided at the inner bottom of the battery case, the bottom surface of the battery case is formed so as to expand outward as the internal pressure of the battery increases, and the amount of deformation of the bottom surface is increased. When the power supply element becomes large to some extent, the lead plate connecting one pole and the bottom surface of the power generating element is broken to cut off the current path, and at the same time, the thin portion on the bottom surface is opened to release gas inside the battery. I have.

[0004]

However, in the above-described conventional safety device, the cover member for sealing the battery case or the inner bottom of the battery case has both the function of the pressure-sensitive switch and the function of the safety valve. Therefore, there is a problem that the configuration becomes very complicated, the number of parts is large, and assembly is troublesome. In addition, the function of the pressure-sensitive switch is realized in the initial stage of the deformation of the same diaphragm and functions as a safety valve in the final stage of the deformation.However, the operation accuracy and reliability of both of these functions are improved. The design was very troublesome, and it was inevitable that the operating characteristics of the pressure-sensitive switch, such as too early or too late, or too early or too late as a safety valve, would vary between products.

The present invention has been made in view of the above-mentioned conventional problems. The purpose of the invention is to realize a function as a pressure-sensitive switch and a function as a safety valve with a simple configuration that is easy to assemble, and to achieve both functions. It is an object of the present invention to provide a battery safety device in which operating characteristics, performance, and reliability can be individually and appropriately set.

[0006]

According to the present invention, a pressure-sensitive switch member is mounted on the inner bottom of a cylindrical metal case having a bottom, and a lid member is mounted on an open end of the battery case to seal the case. Was equipped with a safety valve. In particular, the pressure-sensitive switch member is connected to a fixed pedestal made of an insulator fixed to the peripheral surface of the battery case and one pole of a power generation element in the case, and a central projection penetrates a central hole of the fixed pedestal. Have been
The tip comprises a contact member electrically connected to a central inner bottom surface of the case deformed by the internal pressure of the case.

[0007]

The function of the pressure-sensitive switch is realized by the above-mentioned pressure-sensitive switch member. That is, when the internal pressure of the battery case increases, the pressure also deforms the bottom surface of the case so as to expand outward. When the amount of deformation increases to some extent, the contact member and the case bottom are separated, and the discharge current path of the battery is cut off.

[0008]

FIG. 1 shows a lithium battery having a spiral electrode structure provided with a safety device according to an embodiment of the present invention. Reference numeral 1 denotes a bottomed cylindrical metal battery case, which also serves as a negative electrode terminal as described below. A pressure-sensitive switch member including a fixed base 10 and a contact member 11 is mounted on the inner bottom of the battery case 1, the power generating element 5 is housed together with the organic electrolyte, and the open end of the case 1 is connected to the positive terminal plate 7. And a diaphragm 8 and a sealing gasket 6 made of plastic. The power generating element 5 includes a separator 2, a lithium negative electrode 3, and a positive electrode 4 each formed in a sheet shape, and these are overlapped so that the separator 2 is sandwiched between the lithium negative electrode 3 and the positive electrode 4, thereby forming a spiral shape. It is wound.

The fixed base 10 of the pressure-sensitive switch member is a relatively thick disk made of alumina and has a hole 10a formed in the center. The fixed pedestal 10 is fitted to the inner periphery of the battery case 1 and is arranged at the bottom, and the outer periphery thereof is fixed to the inner periphery of the case 1. The contact member 11 is formed of a metal disk, and has a central protruding portion 11a protruding downward at a central portion thereof.
Are formed by drawing or the like. The contact member 11 is disposed on the fixed pedestal 10, and its central convex portion 11 a penetrates through the central hole 10 a of the fixed pedestal 10 and projects downward.

A lead plate (not shown) derived from the lithium negative electrode 3 of the power generating element 5 is joined to the contact member 11 by welding or the like, and the lithium negative electrode 3 and the contact member 1 are joined together.
1 is electrically connected. And the contact member 11
Is electrically connected to the bottom surface of the battery case 1, whereby the lithium negative electrode 3 and the battery case 1 are electrically connected. This electrical connection may be by using a joint such as welding, or simply by metal-to-metal contact. In terms of connection reliability, for example, resistance welding is more preferable. Thereby, the battery case 1 functions as a negative electrode terminal.

On the other hand, a central portion of the terminal plate 7 of the lid member is formed to protrude outward, and a diaphragm 8 is combined inside the terminal plate 7 to be integrated. The diaphragm 8 is made of metal, and the diaphragm 8 and a lead plate 9 derived from the positive electrode 4 of the power generating element 5 are joined by welding or the like,
The diaphragm 8 and the terminal plate 7 integrated with the diaphragm 8 are electrically connected to the positive electrode 4. Therefore, the terminal plate 7 functions as a positive electrode terminal plate. A gas vent hole 7b is formed in the top surface of the central convex portion of the terminal plate 7.
Is formed downward. Cutting blade 7a
Is opposed to the upper surface of the diaphragm 8 applied to the lower surface of the terminal plate 7.

In the above configuration, when the pressure inside the battery becomes abnormally high, the diaphragm 8 of the lid member expands outward by receiving the pressure, and a force acts to expand the bottom surface of the battery case 1 outward. . When the bottom surface of the battery case 1 bulges outward to some extent, the central convex portion 11a of the contact member 11 and the inner bottom surface of the battery case 1 are separated from each other, thereby interrupting the discharge current path of the battery. This is the function of the pressure-sensitive switch.

When the deformation of the diaphragm 8 increases to a certain degree or more, the diaphragm 8 comes into pressure contact with the cutting blade 7a,
The diaphragm 8 is broken starting from the pressure contact. Then, the gas in the battery case 1 is safely released to the outside through the gas vent hole 7b. This is the function of the safety valve.

As described above, the pressure-sensitive switch and the safety valve are realized by completely different structures. The operating characteristics of the pressure-sensitive switch depend on the degree to which the bottom surface of the case 1 bends with respect to the battery internal pressure. In order to appropriately set this characteristic, for example, as shown in FIG. 2, a linear thin portion 1a concentric with the outer diameter is formed on the bottom surface of the battery case 1 so that the central portion of the bottom surface of the case 1 It can be configured to be deformed by an appropriate pressure and to be separated from the central convex portion 11a of the contact member 11.

[0015]

As described in detail above, according to the present invention, the function as a pressure-sensitive switch that shuts off the discharge current path of the battery when the battery internal pressure rises abnormally and the internal function when the battery internal pressure rises abnormally The functions of the safety valves for releasing the gas are realized by independent and simple configurations, so that the respective components are not complicated and the assembly is easy. In addition, the operating characteristics of the pressure-sensitive switch and the operating characteristics of the safety valve can be designed and adjusted independently, so that the operating accuracy and reliability of both functional parts can be increased, and variations between products Can also be kept very small.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a cylindrical lithium battery provided with a safety device according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part showing another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Battery case 5 Power generation element 6 Sealing gasket 7 Terminal plate 8 Diaphragm 10 Fixed pedestal 10a Center hole 11 Contact member 11a Center convex part

──────────────────────────────────────────────────続 き Continuing on the front page (72) Yoshiro Harada, Inventor 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Hideaki Nakura 5-36-11, Shimbashi, Minato-ku, Tokyo (56) References JP-A-2-112151 (JP, A) JP-A-2-207450 (JP, A) JP-A-3-69857 (JP, U) (58) Field (Int.Cl. ⁶ , DB name) H01M 2/34 H01M 2/12

Claims (2)

(57) [Scope of request for utility model registration] 1. A pressure-sensitive switch member mounted on the inner bottom of a bottomed cylindrical metal battery case, and a lid member mounted on an open end of the case via a sealing gasket to seal the case. Wherein the pressure-sensitive switch member has a fixed base made of an insulator fixed to a peripheral surface of the case;
Connected to one pole of the power generating element in the case, the central convex portion penetrates the central hole of the fixed base, and the tip is electrically connected to the central inner bottom surface of the case deformed by the internal pressure of the case. And a cover member provided with a safety valve operated by the internal pressure of the case. 2. The battery safety device according to claim 1, wherein a thin portion is provided on a bottom surface of the case so that the bottom surface is easily deformed by an internal pressure of the case.