JPH07107836B2 - Explosion-proof battery - Google Patents

Description

TECHNICAL FIELD The present invention relates to an explosion-proof battery having a sealing body provided with an explosion-proof device.

[Conventional technology]

For example, in a cylindrical lithium battery using an organic electrolyte, when an unexpected accident such as the occurrence of an internal short circuit occurs in the battery, gas is generated inside the battery, and the pressure inside the battery is about to rise abnormally, The flexible thin plate bends upward and contacts the cutting edge to destroy it, thereby discharging the gas inside the battery to the outside of the battery and using an explosion-proof device to prevent sudden explosion of the battery, so-called battery explosion. Provision is made (for example, Japanese Utility Model Publication No. 59-15398).

The inventors of the present invention have conducted extensive research on an explosion-proof battery having such an explosion-proof device provided in a sealing body, and have so far developed a battery as shown in FIG.

In the battery shown in FIG. 4, the peripheral edge of the flexible thin plate 40 that closes the gas vent hole 11 of the sealing plate 10 and the annular packing 30 are sandwiched between the flange-shaped peripheral edge portion 22 of the terminal plate 20 and the sealing plate 10. However, when an unexpected accident occurs inside the battery, gas is generated, and the pressure inside the battery rises, the central portion of the flexible thin plate 40 bends upward and is installed on the terminal plate 20, as shown in FIG. The explosion-proof device operates by contacting the cutting edge 24 and being destroyed, and the gas inside the battery is discharged from the gas exhaust hole 23 of the terminal plate 20 to the outside of the battery through the gas vent hole 11 of the sealing plate 10. To prevent the battery from bursting.

[Problems to be Solved by the Invention]

However, in the batteries so far, the operating pressure of the explosion-proof device is set to be almost constant regardless of the temperature, and the explosion-proof device is activated if the pressure inside the battery rises at normal temperature or high temperature.

In addition, in an organic electrolyte-based lithium battery that uses lithium as a negative electrode active material and an organic electrolyte as an electrolyte, from the viewpoint of safety, it is more likely that an explosion-proof device will be used than an explosion-proof battery that uses an aqueous electrolyte such as an alkaline battery. Normal operating temperature range (generally below 60 ° C) because the operating pressure is set quite low
Due to the temperature change inside the battery, the pressure inside the battery temporarily rises, the explosion-proof device operates, and the battery function is lost, or the electrolyte leaked by the operation of the explosion-proof device damages the equipment using the battery. The problem occurs.

In the present invention, as described above, the conventional explosion-proof battery is operated by the explosion-proof device due to a temporary pressure increase due to the temperature change within the normal operating temperature range, the battery function is lost, or the battery leaks due to the leaked electrolyte. It solves the problem that the equipment used is damaged, and the explosion-proof device does not operate with a temporary pressure increase within the normal operating temperature range, and the battery active material causes a pressure increase due to temperature rise such as internal short circuit. It is an object of the present invention to provide an explosion-proof battery capable of preventing the battery from bursting by operating the explosion-proof device against a continuous increase in pressure that continues until it disappears.

[Means for Solving the Problems]

The means for achieving the above object will be described with reference to FIG. 1 corresponding to the embodiment of the present invention.
By disposing the annular thermal deformation member 50 in the space above the flexible thin plate 40 in the space 60 formed by the main body 21 of the terminal board 20, the operating pressure of the explosion-proof device can be changed depending on the temperature. It is the one.

[Action]

As described above, if the annular heat-deformable member 50 is arranged in the space 60 formed by the sealing plate 10 and the main body portion 21 of the terminal plate 20 above the flexible thin plate 40, normal use is possible. When the pressure rises within the temperature range, as shown in FIG. 2, the fulcrum when the flexible thin plate 40 bends upward becomes the inner peripheral end of the annular thermal deformation member 50, and the flexible thin plate 40 bends. The diameter of the hollow part is an annular thermal deformation member
Regulated by 50. As a result, since the diameter of the flexible portion of the flexible thin plate 40 becomes small, unless there is a large pressure increase, the flexible thin plate 40 does not bend to the extent that it contacts the cutting edge 24, and the operating pressure of the explosion-proof device is reduced. Becomes higher. Therefore,
The operation of the explosion-proof device due to a temporary pressure increase within the normal operating temperature range is prevented. On the other hand, in the continuous pressure increase itself accompanied by the temperature rise, when the temperature rises up to near the melting point of the ring-shaped heat deformable member 50, the ring-shaped heat deformable member 50 is deformed by heat, so that it is shown in FIG. As described above, the fulcrum when the flexible thin plate 40 bends upward is the bending point of the boundary between the main body portion 21 of the terminal plate 20 and the brim-shaped peripheral portion 22, and the bending of the flexible thin plate 40 is the terminal plate 20. As a result, the diameter of the flexible portion of the flexible thin plate 40 becomes larger than that in the case of a temporary pressure increase within the normal operating temperature range. As a result, the flexible thin plate 40 will bend to the extent that it contacts the cutting edge 24 at a pressure lower than the pressure increase within the normal operating temperature range, and the explosion-proof device will operate at a pressure within the range where safety can be secured. Come to do. As the material of the annular heat-deformable member 50 as described above, a heat-deformable material having a melting point of 90 to 130 ° C., particularly polyethylene, ethylene-vinyl acetate resin, or the like having a melting point of 90 to 130 ° C. is used because of its ease of molding. It is preferable to use a plastic synthetic resin.

〔Example〕

FIG. 1 is an enlarged sectional view showing an embodiment of the explosion-proof battery of the present invention. In the figure, reference numeral 1 is a sealing body provided with an explosion-proof device, and this sealing body 1 is composed of a sealing plate 11 having a gas vent hole 11 formed therein, a main body portion 21 and a flange-shaped peripheral portion 22.
Cap-shaped terminal board with gas exhaust hole 23 and cutting edge 24 in 21
20 and annular packing 30 to be placed on the periphery of the sealing plate 10.
A peripheral edge portion is disposed on the annular packing 30, and the flexible edge is clamped by the flange-shaped peripheral edge portion 22 of the terminal plate 20 and the sealing plate 10 together with the annular packing 30 by caulking the bent edge 12 of the sealing plate 10. A heat-deformable thin plate 40, and an annular heat-deformable member 50 is arranged at a portion above the flexible thin plate 40 in the space 60 formed by the sealing plate 10 and the main body portion 21 of the terminal plate 20. .

Although the sealing plate 10 has a shallow container shape,
The opening edge is bent inward when the sealing body 1 is assembled, and the bent edge 12 is caulked to make a terminal plate.
The flange-shaped peripheral portion 22 of 20 is pressed to make the sealing body 1 air-tight and liquid-tight. The terminal plate 20 is composed of a body having a body portion 21 and a brim-shaped peripheral portion 22 and having a low height. The body portion 21 is provided with a cutting edge 24 and a gas exhaust hole 23.
Is composed of an upper plate portion and a peripheral wall portion, and the cutting blade 24 partially cuts into the upper plate portion of the main body portion 21 of the terminal plate 20 and bends the portion from the tip side to the inner side (lower side in the drawing). The hole formed in the upper plate portion of the main body portion 21 by the formation of the cutting edge 24 serves as a gas exhaust hole 23. The brim-shaped peripheral edge portion 22 of the terminal plate 20 is bent obliquely upward, and in the present embodiment, the tip end portion is bent substantially horizontally. The inner diameter of the annular packing 30 is formed larger than the outer diameter of the main body portion 21 of the terminal plate 20,
The terminal plate 20 is sealed radially outward from the main body portion 21. The peripheral edge of the flexible thin plate 40 is sandwiched between the collar-shaped peripheral edge 22 of the terminal body 20 and the sealing plate together with the annular packing 30, but the central portion of the flexible thin plate 40 is provided with the gas passage of the sealing body 10 in normal times. The pores 11 are closed. The ring-shaped heat-deformable member 50 is formed of, for example, polyethylene, and as described above, the flexible thin plate 40 is resistant to a temporary pressure increase that occurs within the normal operating temperature range.
By controlling the diameter of the flexible part of the explosion-proof device to prevent malfunction,
Further, when there is a pressure increase that causes a temperature rise such as the occurrence of an internal short circuit of the battery, when the temperature rise approaches the melting point of the annular heat deformable member 50, the heat deformable member 50 may be thermally deformed. The flexible portion of the flexible thin plate (40) is enlarged so that the explosion-proof device operates at a low pressure within a range where safety can be ensured. The inner diameter of the annular heat-deformation member 50 is formed to be larger than the inner diameter of the upper side so that thermal deformation is likely to occur when the internal pressure rises accompanying temperature rise.

The assembling of the sealing body 1 is performed as follows.

First, the annular packing 30 is arranged on the bottom peripheral edge of the container-shaped sealing plate 10 whose opening edge is not bent inward, and the peripheral edge is placed on the annular packing 30. The flexible thin plate 40 is placed in the sealing plate 10. Next, an annular thermal deformation member 50 is arranged on the flexible thin plate 40,
A terminal plate (20) is arranged from above, the opening edge of the sealing plate (10) is bent inward, and the bent edge (12) is caulked to form a flexible thin plate (40).
Of the terminal plate 20 and the ring-shaped packing 30 on the brim-shaped peripheral portion of the terminal plate 20.
The assembly of the sealing body 1 is completed by sandwiching the sealing plate 22 with the sealing plate 10.

Then, the sealing body 1 assembled as described above is attached to the opening of the battery case 2 in which the power generating element 3 has been filled in advance through the insulating packing 4 to produce an explosion-proof battery. That is, in the battery case 2, the power generating element 3, that is, the positive electrode active material, the negative electrode active material, the electrolytic solution,
Insulate the sealing body 1 by loading a separator or the like in a state suitable for causing a battery reaction when necessary, and then forming a constriction near the opening end of the battery case 2 for supporting the lower peripheral edge of the sealing body 1. Battery case 2 with packing 4
After that, the opening edge of the battery case 2 is tightened inward to close the opening of the battery case 2. As a result, this battery is kept in a sealed state in normal times. The power generation element 3 may have a publicly known configuration, and a representative example thereof is an organic electrolyte-based power generation element, for example, a negative electrode plate in which lithium is used as a negative electrode active material and the plate-like material is pressure-bonded to a current collector. And a positive electrode plate in which a positive electrode mixture containing manganese dioxide as a positive electrode active material (a positive electrode mixture prepared by mixing the above manganese dioxide, graphite, and a fluororesin-based binder) is held by a current collector with a separator interposed A spirally wound electrode and a mixed solvent of, for example, propylene carbonate and 1,2-dimethoxyethane, with 1 mol of lithium perchlorate.
/ l Examples include those that are composed of dissolved organic electrolytes.

Then, when a temporary pressure rise occurs in this battery within the normal operating temperature range, the flexible thin plate 40 bends upward,
The fulcrum of the flexible portion at that time is the inner peripheral end of the annular thermal deformation member 50, as shown in FIG. 2, and the diameter of the flexible portion of the flexible thin plate 40 is reduced. That is, the diameter of the flexible portion of the flexible thin plate 40 is regulated by the annular thermal deformation member 50, and the flexible thin plate 40
The diameter of the flexible portion of the is reduced. As a result, the flexible thin plate 40
Is hard to bend, and unless a large pressure rise occurs, the flexible thin plate 40 does not bend enough to contact the cutting edge 24, and the explosion-proof device is used for a temporary pressure rise that occurs within the normal operating temperature range. Does not work, the battery is kept in a sealed state, and the function as a battery is maintained. However, if there is a large temperature rise such as the occurrence of an internal short circuit inside the battery, and a continuous pressure rise such that the internal pressure of the battery rises until the battery active material is exhausted, the temperature rise will increase. When the melting point of the heat-deformable member 50 approaches, the heat-deformable member 50 undergoes heat deformation, and the fulcrum of the flexible portion of the flexible thin plate 40 is, as shown in FIG. It becomes a bending point of the boundary between the brim-shaped peripheral portion 22 and the flange-shaped peripheral portion 22, and the diameter of the flexible portion of the flexible thin plate 40 is regulated by the terminal plate 20, so that it is temporary within the normal operating temperature range. It becomes larger than the case of pressure increase. As a result, the flexible thin plate 40 cuts the blade with a lower pressure than in the case of a temporary pressure increase that occurs within the normal operating temperature range.
Bends against 24 and activates explosion protection.

Thus, in this battery, the operating pressure of the explosion-proof device varies depending on the temperature, and the explosion-proof device does not operate due to a temporary pressure increase caused by a temperature change within the normal operating temperature range, and so-called malfunction is prevented. , The occurrence of internal short circuit, etc.
When a continuous pressure increase accompanied by a temperature rise occurs, which causes the battery to burst if the explosion-proof device does not operate, the explosion-proof device operates at a low pressure to prevent the battery from bursting and ensure safety.

FIG. 6 shows the operating state of the explosion-proof device of the sealing body used in the battery of the present invention and the conventional sealing body used in the battery as shown in FIG. That is, FIG. 6 shows the temperature on the horizontal axis and the operating pressure of the explosion-proof device on the vertical axis, and shows the relationship between the operating pressure and the temperature of the explosion-proof device for both sealing bodies.

In the operation test of the above explosion-proof device, the sealing body was attached to the opening of the container-shaped test jig, and the temperature was set to 20 ° C, 60 ° C, 80 ° C, 100 ° C, 110 ° C.
C., 120.degree. C., 130.degree. C., 140.degree. C. and 150.degree. C. were changed, and argon gas was supplied to the test jig from the bottom side, and the operating pressure of the explosion-proof device for the sealing body was examined. As a member of the sealing body 1, the sealing plate 10 has a thickness of 0.3 mm of a stainless steel plate (SUS
(430 plates) molded into a shallow container, the annular packing 30 is made of polypropylene, the flexible thin plate 40 is a 0.015 mm thick titanium plate, and the annular heat-deformable member 50 is polyethylene (melting point). The terminal plate 20 is formed of a rolled steel plate (SPC plate) having a thickness of 0.3 mm, the surface of which is nickel-plated.

As shown in FIG. 6, in the case of the sealing body used in the conventional battery (conventional product), the operating pressure of the explosion-proof device is constant at about 6 kg / cm ² regardless of the temperature. In the case of the seal used, the operating pressure of the explosion-proof device is high when the temperature is low, and the operating pressure of the explosion-proof device is about 6k when the temperature is high.
The value is as low as g / cm ^2, which is the same as the case of the sealing body (conventional product) used for conventional batteries. Therefore, in the sealing body used for the battery of the present invention, the operating pressure of the explosion-proof device changes depending on the temperature, the operating pressure of the explosion-proof device is high while the temperature is low, and the operating pressure of the explosion-proof device is low at high temperature, so that the battery is normally used. The explosion-proof device does not operate with a temporary pressure increase that occurs within the temperature range, and when a continuous pressure increase with a large temperature increase occurs, the explosion-proof device operates at a low pressure to ensure safety.

〔The invention's effect〕

As described above, in the present invention, the sealing plate 10 and the terminal plate 20
By disposing the annular thermal deformation member 50 in a portion of the space 60 formed by the main body portion 21 and above the flexible thin plate 40, the operating pressure of the explosion-proof device can be changed depending on the temperature, and The temporary explosion in the normal operating temperature range does not activate the explosion proof device, preventing the so-called malfunction of the explosion proof device, while the explosion proof device is safe when a continuous pressure increase accompanying temperature rise occurs. It was possible to prevent the battery from bursting by operating at a low pressure within the range that can be secured and to ensure safety.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view showing an embodiment of the explosion-proof battery of the present invention. FIG. 2 is an enlarged cross-sectional view of an essential part showing a state in which the flexible thin plate is bent in the normal operating temperature range of the battery shown in FIG. 1, and FIG. FIG. 7 is an enlarged cross-sectional view of a main part showing a state in which the flexible thin plate in FIG. FIG. 4 is an enlarged sectional view of an essential part showing a conventional explosion-proof battery, and FIG. 5 is an enlarged sectional view of an essential part of the conventional battery shown in FIG. 4 in an operating state. FIG. 6 is a diagram showing the relationship between the operating pressure and temperature of the explosion-proof device of the sealing body used in the battery of the present invention and the conventional sealing body used in the battery. 1 ... Sealing body, 2 ... Battery case, 3 ... Power generation element, 4
...... Insulating packing, 10 ...... Seal plate, 11 ...... Gas vent, 12 ...... Bend edge, 20 ...... Terminal plate, 21 ...... Main body part, 22
…… Brim edge, 23 …… Gas exhaust hole, 24 …… Cut blade, 30…
… Annular packing, 40… Flexible thin plate, 50… Annular heat deformation member, 60… Space

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Tomio Kitamura 1-88, Tora, Ibaraki-shi, Osaka Prefecture Hitachi Maxell Co., Ltd. (72) Inventor Osamu Kajii 1-1-88, Tora, Ibaraki-shi, Osaka Hitachi Maxel Co., Ltd. (56) Bibliography Sho 60-20282 (JP, Y2)

Claims (2)

[Claims] 1. An explosion-proof battery in which a sealing body 1 equipped with an explosion-proof device is attached to an opening of a battery case 2 containing a power-generating element 3 through an insulating packing 4, the sealing body 1 being a gas. A gas exhaust hole 23 and a cutting edge 24 are formed in the main body portion 21 and are composed of a sealing plate 10 having a ventilation hole 11 formed therein, a main body portion 21 and a flange-shaped peripheral portion 22.
The cap-shaped terminal plate 20 provided with, the annular packing 30 arranged on the peripheral portion of the sealing plate 10, the peripheral portion is arranged on the annular packing 30 by caulking the bent edge 12 of the sealing plate 10. A flange-shaped peripheral portion of the terminal board 20 together with the annular packing 30.
A flexible thin plate 40 sandwiched between 22 and the sealing plate 10 is provided, and the sealing body 1 has a main body portion of the sealing plate 10 and the terminal plate 20.
An annular thermal deformation member 50 is arranged in a space 60 formed by 21 and above the flexible thin plate 40, and the annular thermal deformation member 50 can change the operating pressure of the explosion-proof device depending on the temperature. Explosion-proof battery characterized by doing so. 2. An explosion-proof battery according to claim 1, wherein the melting point of the annular heat-deformable member 50 is 90 to 130 ° C.