JPH09237620A - Sealed battery and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate hazardousness of a burst or the like of a battery due to a rise of its internal pressure, by stably maintaining a valve operating pressure over a long period even when a valve unit is thin in its thickness, so that the battery can follow up even to changing of its internal pressure according to a rapid temperature rise, in a safety valve device formed into a thin type for the sealed battery. SOLUTION: As an elastic valve unit 7 for a safety valve device, after mixing an olefin system resin or the like with an ethylene propylene rubber material (EPDM), the EPDM crosslinkaged is used simultaneously with molding in a prescribed shape, the material, setting its thickness to 1.0mm or more, is compressed 10 to 50% in a thickness direction, to be arranged in a valve chamber 6, so that forming into a thin type is made capable of the safety valve device. A valve operating pressure is decreased against a rise of internal pressure according to a rapid temperature rise of a battery, so as to make exhaust power follow up, high safety and reliability are obtained as the battery.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sealed battery having improved safety as a battery, and more specifically, a safety valve device for sealing a battery container is made thinner, and a gas which is abnormally generated in the battery at high temperature is exhausted. It is about improving abilities.

[0002]

2. Description of the Related Art In recent years, with the spread of various portable devices, batteries,
In particular, rechargeable secondary batteries are widely used. Conventionally, lead storage batteries and nickel-cadmium storage batteries have been used as batteries used in these devices, but nickel-hydrogen storage batteries and lithium secondary batteries have been newly added.

Among these rechargeable batteries, in batteries using an aqueous electrolyte such as a lead storage battery, a nickel-cadmium storage battery and a nickel-hydrogen storage battery, the gas generated inside the battery is produced by the so-called Neumann method. By consuming on the opposite electrode, the battery can be sealed.

On the other hand, in a battery using a non-aqueous electrolyte such as a lithium secondary battery, gas cannot be lost inside the battery, and therefore, overcharging and overdischarging have been avoided to achieve hermetic sealing.

However, failure of the charger, misuse of the battery,
When an abnormal situation occurs due to an external short circuit or the like, the internal pressure of the battery may rise abnormally and lead to rupture. In order to prevent the battery from bursting, the secondary battery is usually equipped with a safety valve device so that the gas generated inside the battery is released to the outside when the internal pressure of the battery exceeds a preset value.

Hereinafter, a sealed battery having a safety valve device will be described. FIG. 4 is an example of a vertical cross-sectional view of an upper portion of a general sealed battery. In FIG. 4, a metal case 1 which is a battery container is a metal dish having a gas vent hole 2a formed in the center through a gasket 3 which plays a role of electrical insulation and airtightness in the upper part of the case 1. The sealing plate 2 is fixed by crimping. Although not shown in detail in the inside of the case 1, a power generating element 4 including an electrode plate group in which a positive electrode plate and a negative electrode plate are superposed on each other via a separator and spirally wound, and an alkaline electrolyte are provided. It is stored. Further, on the upper side of the dish-shaped sealing plate 2, there is integrally provided a cap-shaped positive electrode terminal 5 which is also used for constituting a safety valve device. The positive electrode terminal 5 has a cap shape having a flange portion, and a gas exhaust port 5 is provided in a part thereof.
a is formed. A valve chamber 6 is formed in a space surrounded by the positive electrode terminal 5 and the sealing plate 2, and an elastic valve body 7 is housed in the valve chamber 6 in a compressed state. The elastic valve body 7 is generally one that utilizes the elasticity of a metal spring or rubber.

In the sealed battery having the above structure, when the internal pressure of the battery rises due to an excessive inflow of charging current due to a failure of the charger or an over-discharging accompanied by the reversal of polarity, The gas in the high pressure state is supplied to the gas vent 2a.
Acts on the elastic valve element and pushes it up, and the elastic valve element is discharged to the outside from the gas exhaust port 5a of the positive electrode terminal 5.

Normally, the above-mentioned safety valve device used is set so that gas is released to the outside when the internal pressure of the battery reaches 10 kg / cm ² or more. Therefore, when overcharging is performed to such an extent that abrupt gas generation does not occur, the internal pressure of the battery increases as the gas absorption capacity of the negative electrode decreases. At this time, even if the gas inside the battery is released to the outside, there is no problem, and if the charging is stopped and the internal pressure of the battery drops, the safety valve device returns to its original shape and becomes usable again. Further, the rated allowable pressure of the safety valve may be increased to about 20 kg / cm ² in order to enable rapid charging. To set the rated allowable pressure,
This is performed by increasing the hardness of the elastic body forming the valve body or increasing the compression rate of the valve body.

[0009]

With respect to the safety valve device having the structure and function as described above, it has been demanded to increase the capacity of the battery due to the increase in power consumption accompanying the multifunctionalization of the equipment in which the battery is used in recent years. Therefore, the safety valve device is required to be thin as one of means for increasing the capacity. When the safety valve device is made thin, the internal volume of the battery is substantially increased, and the capacity of the power generation element 4 shown in FIG. 4 is increased by that amount, so that the capacity of the battery can be increased. FIG. 5 shows an example of an upper vertical cross-sectional view of a sealed battery in which the safety valve device is thinned.

In FIG. 5, an opening of a metal case 1 which is a battery container accommodating a power generating element has a low height and a thin safety valve device via a gasket 3 which plays a role of electrical insulation and airtightness. It is sealed with.

The thin safety valve device has a shallow plate-like sealing plate 2.
And a short cap-shaped positive electrode terminal 5 welded to the central portion of the upper surface thereof, and a valve chamber 6 of low height provided between them.
It is composed of a thin elastic valve body 7 housed inside in a compressed state.

However, by making the safety valve device thin in this way, when a current more than a set value flows into the battery and an abnormality occurs in the gas, the compressed elastic valve element in the valve chamber is pressurized with the gas. However, since the valve chamber does not have a sufficient margin space and the amount of deformation is small, the discharge rate from the gas exhaust port cannot keep up with the gas generation rate inside the battery. Therefore, the internal pressure of the battery rises sharply, leading to rupture. In addition, even if the temperature inside the battery rises, the elastic rubber valve body thermally expands to fill the valve chamber with less space, and the original valve body operating function (exhaust function) cannot be maintained. Leading to.

In this regard, in Japanese Patent Laid-Open No. 41204/1993, the melting point of at least one of the packing material and the safety valve body is set to 270 ° C. or less in order to ensure safety when the battery is thrown into a fire. Is described. However, the invention described in this publication does not intend to make the safety valve device thin.

As the elastic valve body material, natural rubber, SB
R rubber and ethylene propylene rubber have been proposed. Of these, ethylene-propylene rubber is the most excellent, but it gradually loses rubber elasticity mainly due to oxidation. Since the valve operating pressure of the safety valve device is lowered due to the change of rubber elasticity with time, it is difficult to set the valve operating pressure for ensuring long-term reliability such as prevention of leakage of electrolyte.

According to the present invention, the elastic valve body material is improved so that the valve body and the safety valve device can be made thinner, and the reliability that the valve operating pressure can be stably maintained for a long period of time is ensured.
It can follow changes in internal pressure that accompany a sudden temperature rise in the battery,
It is an object of the present invention to provide a sealed battery that can solve safety problems such as rupture caused by an increase in internal pressure.

[0016]

In order to achieve the above object, in the present invention, at least one selected from an olefin resin, a styrene resin, an amide resin and a fluorine resin is used as an elastic valve body of a safety valve device. A resin (hereinafter referred to as RESIN) of a type and an ethylene propylene rubber raw material (hereinafter referred to as EPDM) were mixed, and then molded and crosslinked at the same time.

Therefore, the elastic valve body of the present invention basically has a structure in which RESIN having a softening temperature lower than that of EPDM is incorporated therein. In this case RESI
The amount of N mixed in is preferably 5 to 30% by weight with respect to EPDM.

With such a composition, 100 to 1
The valve operating pressure of the safety valve device at a high temperature of 20 ° C. is set to be 60 to 20% of that at a normal temperature.

In order to obtain a stable rated allowable pressure of the thin safety valve device, the elastic valve element has a thickness of 1.0 mm or more,
It is arranged in the valve chamber space of the safety valve device after being compressed by 10 to 50% in the thickness direction.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The elastic valve body of the present invention as defined in claim 1 comprises a hard phase (RESIN phase) having thermoplasticity and a soft phase (EPDM phase) imparting elasticity. Therefore, when a large current of a set value or more flows in the battery, which causes the battery temperature to rise and an abnormal gas to occur, the hard phase is softened, and the operating pressure of the elastic valve body decreases. The gas discharge rate from the gas outlet is substantially increased. Since the gas discharge rate follows the internal gas generation rate, it is possible to prevent the battery internal pressure from rising and prevent the battery from bursting.

Since EPDM, after being mixed with RESIN, is molded into a predetermined shape as a valve body and simultaneously crosslinked, the crosslinked structure of ethylene propylene rubber is maintained even if RESIN is softened at high temperature. This ethylene propylene rubber prevents excessive reduction of valve operating pressure,
After the valve is actuated, the gas exhaust port is closed again and the outside air does not flow into the battery. This makes it possible to prevent ignition due to inflow of air or oxygen from the outside into the battery, particularly in nickel-hydrogen storage batteries and lithium secondary batteries.

Further, the elastic valve body is made of RESIN and EPDM.
Since it is a mixture with, it is difficult for oxygen molecules to permeate from the surface of the elastic valve body to the inside, and the destruction of the cross-linked structure of ethylene propylene rubber due to oxidative deterioration is suppressed, stabilizing the valve operating pressure for a long time, that is, reliability. Can be secured.

The invention according to claim 3 is the E of RESIN
It defines the mixing ratio for PDM. RES
If the mixing ratio of IN is 5% by weight or more, EPD after mixing
When the safety valve device is configured as an elastic valve body by bridging M,
Even if a large current exceeding the set value flows in the battery and the battery temperature rises and gas abnormalities occur, the hard phase is softened by heat, and the operating pressure as the elastic valve body decreases, The gas discharge rate from the gas outlet is substantially increased. Since the gas discharge rate follows the internal gas generation rate, it is possible to prevent the battery internal pressure from rising and prevent the battery from bursting. Furthermore, due to the effect of RESIN to suppress the oxidation of ethylene propylene rubber, it is possible to prevent a decrease in valve operating pressure in a normal operating temperature range.

On the other hand, when the mixing ratio is 30% by weight or more, when EPDM is crosslinked after mixing and a safety valve device is constructed as an elastic valve body, when a large current more than a set value flows into the battery and the battery temperature rises. A large amount of hard phase is softened by heat and the valve operating pressure is excessively lowered, and the gas exhaust port is opened after the valve is operated. Therefore, in nickel-hydrogen storage batteries, etc., they are ignited by the inflow of air or oxygen into the battery from the outside.
Therefore, the mixing amount of RESIN is 5 with respect to EPDM.
-30% by weight is desirable.

The invention according to claim 8 defines an elastic valve body. The thickness of the valve body varies depending on various battery sizes, but if the thickness is 1.0 mm or more, the valve body composition described above causes a rapid temperature rise when the battery is abnormally used. Exhaust gas can be handled even when the internal pressure of the battery rises, and the safety valve device can be made thin.

Further, when the compression ratio of the elastic valve body in the thickness direction is set to less than 10%, the sealing property (closure property) of the safety valve device cannot be secured. That is, the battery electrolyte leaks. Further, when the compression rate of the elastic valve body is increased to 50% or more, the elastic limit of rubber is exceeded, so that the function as an elastic body is impaired and the exhausting ability of the safety valve device is lost. Therefore, the compression rate of the elastic valve body is preferably 10 to 50%.

[0027]

Embodiments of the present invention will be described below with reference to FIG. FIG. 5 is a vertical cross-sectional view of an upper portion of a sealed battery in which the safety valve device is thinned. The structure is such that the sealing plate 2 is provided with a cap-shaped positive electrode terminal 5 which is also used for forming a safety valve device. The positive electrode terminal 5 has a cap shape, and a gas exhaust port 5a is formed in a part thereof. A valve chamber 6 is formed in a space surrounded by the positive electrode terminal 5 and the sealing plate 2, and an elastic valve body 7 is arranged in the valve chamber 6 in a compressed state.

(Example 1) A thin safety valve device shown in FIG. 5 was constructed, and the mixing ratio of RESIN and EPDM of the valve body 7 was examined.

RESIN was mixed with EPDM at a ratio of 30% by weight, 15% by weight and 5% by weight, and a vulcanizing agent was added thereto to form a valve body, and at the same time, at a temperature of about 180 ° C. Resilient valve bodies that were crosslinked by heating for 5 minutes were prepared. Using these valve elements, safety valve devices A, B and C which are made thin are constructed. Note that polypropylene, which is an olefin resin, was used as the RESIN component.

As a comparative example, RESIN was mixed in a proportion of 50% by weight with respect to EPDM, molded into a valve body shape, and at the same time, a safety valve device D using a crosslinked elastic valve body was used.
As a conventional example, a safety valve device E using an elastic valve element made only from EPDM was constructed. In addition, the above A ~
The elastic valve bodies of E all had a thickness of 2.0 mm and a compression rate of 30% when the safety valve device was constructed. When the thickness of the elastic valve element used in the conventional safety valve device is 4.0 mm, the valve element thickness is reduced by 50%.

Using the safety valve devices A to C of the present invention, A size sealed nickel-metal hydride storage batteries having a nominal capacity of 1600 mAh were produced, and these batteries were designated as batteries a, b and c, respectively.

Using the safety valve device D of the comparative example and the safety valve device E of the conventional example, sealed nickel-metal hydride storage batteries similar to those described above were produced and designated as batteries d and e, respectively. Above a to e
(Table 1) shows the results of performing a burst test on the assumption that control failure of the charger was carried out by continuous overcharging at a current of 8 A (corresponding to 5 C).

[0033]

[Table 1]

From Table 1, no rupture or ignition was found in the batteries a, b and c according to the present invention. On the other hand, in the battery d of the comparative example, 11 out of 50 cells
The cell ignited. This is because the resin phase in the valve body softens due to the rise of the battery temperature in the overcharged state, and since the amount of polypropylene that is RESIN is large, the valve operating pressure drops excessively, and the gas exhausted from the cap even after the valve operates. It is considered that the mouth was opened and the outside air flowed into the battery. In the battery e of the conventional example, 48 cells out of 50 cells burst. This is because the EPDM forming the valve body thermally expands due to the increase in the battery temperature and the battery internal pressure in the overcharged state and almost completely fills the valve chamber, and the exhaust function is deteriorated. Therefore, the safety valve device is made thin. Therefore, it is considered that it occurred more significantly.

In order to confirm the above results, the valve operating pressure maintenance rate (ratio when the initial value is 100) accompanying the temperature rise of the safety valve devices A to E of the batteries a to e was measured next. The result is shown in FIG.

From FIG. 1, safety valve devices A and B according to the present invention are shown.
The valve operating pressure in C and C begins to decrease in proportion to the amount of resin mixed in the valve body from around 100 ° C. due to the softening of the resin phase in the valve body due to the temperature rise, and the valve operating pressure at room temperature of 60 to The temperature decreases to 20%, and at a temperature higher than 20%, the closing function of the elastic valve body is maintained by the crosslinked EPDM, and the valve operating pressure is maintained almost constant. Therefore, the valve element is more likely to be plastically deformed and the exhaust function is improved as much as the maintenance rate of the valve operating pressure due to the temperature increase is reduced. as a result,
As shown in (Table 1), it shows high safety in batteries.

On the other hand, in the safety valve device D of the comparative example, the softening of the resin phase in the valve body due to the temperature rise causes the valve operating pressure to be excessively reduced, and the elastic valve body does not exhibit the function of closing the valve. Confirms the results in. Further, in the safety valve device E of the conventional example, the valve operating pressure is increased, which indicates that the EPDM is thermally expanded and the exhaust function is decreased due to the temperature increase, which corroborates the result of the battery in (Table 1).

From the above results, the present invention can provide a safety valve device which can be thinned and which ensures high safety in a battery.

(Embodiment 2) A to A shown in the above Embodiment 1
Using 5 kinds of safety valve devices of E, the heat deterioration resistance of the elastic valve body was examined. Atmosphere temperature 6
The valve working pressure was measured after storing for a certain period in an environment of 5 ° C. The relationship between the storage period and the valve operating pressure maintenance rate is shown in FIG. As a measure of the long-term reliability of the valve operating pressure of the safety valve device, the valve operating pressure maintenance rate was set at 85% or more. From FIG. 2, as compared with the conventional safety valve device E using only EPDM, the safety valve devices A, B, C and RESIN and EPDM which are mixed and molded into a valve body shape and at the same time use a crosslinked elastic valve body are provided. The degree of deterioration of D due to heat is small. At the same time, RESIN EPDM
It can also be seen that long-term heat resistance is improved by increasing the mixing ratio with respect to. Therefore, when the mixing ratio of RESIN to EPDM is 5% by weight or more, it is clear that the reduction of the valve operating pressure can be prevented by the oxidation inhibiting effect of EPDM, and a safety valve device with high long-term reliability can be provided.

Example 3 The kind of resin which is the RESIN component that constitutes the elastic valve body together with the EPDM was examined.

Polypropylene, polystyrene, and polyamide 6 were used as resin components and mixed with EPDM at a mixing ratio of 15% by weight, respectively, and molded into a valve body shape, and at the same time, crosslinked to produce an elastic valve body, Safety valve devices F, G, and H that are made thin by using these valve bodies are configured.

Further, as a conventional example, a safety valve device E using an elastic valve body made only from EPDM was prepared. The elastic valve bodies all had a thickness of 2.0 mm, and the compression ratio in the thickness direction was 30% when the safety valve device was constructed. When the thickness of the elastic valve element used in the conventional safety valve device is 4.0 mm, the valve element thickness is reduced by 50%.

Using the safety valve devices F to H of the present invention, A size sealed nickel-metal hydride storage batteries having a nominal capacity of 1600 mAh were produced and designated as batteries f, g and h, respectively. A battery e using the safety valve device E was also prepared as a conventional example. Each of the four types of batteries e to h described above was manufactured in 50 cells, and a burst test assuming a control failure of the charger was conducted at 8A.
The results of carrying out continuous overcharge at a current (corresponding to 5C) are shown in (Table 2).

[0044]

[Table 2]

From Table 2, no rupture or ignition was found in the batteries f, g and h according to the present invention. On the other hand, in the battery e of the conventional example, 48 out of 50 cells
The cell burst. This is because the EPDM in the safety valve device thermally expands due to the rise of the battery temperature and the battery internal pressure in the overcharged state, and the exhaust function of the battery internal pressure is lowered.

In order to confirm the above results, the battery e
The maintenance rate of the valve operating pressure (the ratio when the initial value is 100) with the temperature rise of the safety valve devices E to H was measured.
The result is shown in FIG.

As shown in FIG. 3, the valve operating pressure in the safety valve devices F, G and H according to the present invention starts to decrease from around 100 ° C. due to the softening of the resin phase in the valve body due to the temperature rise, and the valve operating at the normal operating temperature. The pressure drops to 50-40%,
At a temperature higher than that, the closing function of the elastic valve body is maintained by the crosslinked EPDM, and the valve operating pressure is kept almost constant. Therefore, the valve element is more likely to be plastically deformed and the exhaust function is improved as much as the maintenance factor of the valve operating pressure due to the temperature increase is reduced. As a result, as shown in (Table 2), the battery shows high safety. The safety valve device E of the conventional example
Shows that the EPDM thermally expands due to the temperature rise and the exhaust function is lowered, and thus the valve operating pressure rises.
It corroborates the results with the batteries in (Table 2).

(Example 4) The thickness of the elastic valve element constituting the safety valve device was examined.

Polypropylene was used as a RESIN component, mixed with EPDM at a mixing ratio of 15% by weight, and molded into a predetermined valve body shape, and at the same time, a cross-linking treatment was carried out to produce an elastic valve body. The thickness of the valve body was 1.0 mm, 2.0 mm, and 3.0 mm when molded into the valve body shape.
Safety valve devices I, J, and K of the present invention using these valve bodies were made thin.

As a comparative example, the safety valve device L was constructed by using an elastic valve element having the same elastic valve element composition as described above and a valve element thickness of 0.7 mm.

All the elastic valve elements had a compression ratio of 30% in the thickness direction when forming a safety valve device. Using the above safety valve devices I, J, K and L, a nominal capacity of 160
A sealed size nickel-metal hydride storage battery of 0 mAh of A size was produced and designated as batteries i, j, k and l, respectively.

Fifty cells each of the four types of batteries i to l were prepared and subjected to a burst test in which a control failure of the charger was assumed.
The results of carrying out continuous overcharge at a current of A (corresponding to 5C) are shown in (Table 3).

[0053]

[Table 3]

From Table 3, no rupture or ignition was observed in the batteries i, j and k according to the present invention. On the other hand, in the battery 1 of the comparative example, 21 cells out of 50 cells burst. This is because the amount of deformation of the elastic valve element in the safety valve device is small with respect to the increase in battery temperature and battery internal pressure in the overcharged state.
It is considered that this is because the exhaust function of the internal pressure of the battery deteriorated.

The thickness of the elastic valve element of the safety valve device varies depending on various battery sizes.
If the thickness is 0 mm or more, it is possible to provide a safety valve device that ensures high safety in batteries.

(Embodiment 5) The compressibility of the elastic valve element constituting the safety valve device when it was installed in the valve chamber was examined. Using polypropylene as the RESIN component, E
An elastic valve body was prepared by mixing the PDM with a mixing ratio of 15% by weight, molding the mixture into a predetermined valve body shape, and simultaneously performing a crosslinking treatment. When molding into a valve body shape, the thickness of the valve body is 2.
0 mm. When constructing a thin safety valve device using this valve body, the compression ratio in the thickness direction is 10%, 30%,
50%, and these were designated as safety valve devices M, N and O.

As a comparative example, the composition and shape of the elastic valve body are the same as those described above, and the safety valve device P using the elastic valve body whose compression rate in the thickness direction is 5% and the composition and shape of the elastic valve body are shown. In the same manner as described above, the safety valve devices Q each using an elastic valve body having a compression rate in the thickness direction of 55% were configured.

Using the safety valve devices M to Q, the nominal capacity 1
A sealed size nickel-metal hydride storage battery of A size of 600 mAh was prepared and used as batteries m, n, o, p and q, respectively.

Fifty types of batteries of the above-mentioned m to q were produced for each 50 cells, and a burst test was conducted assuming a control failure of the charger.
The results of continuous overcharging with a current of A (corresponding to 5C) are shown in (Table 4).

[0060]

[Table 4]

From Table 4, the batteries m, n, o according to the present invention are shown.
In the battery p of Comparative Example, neither rupture nor ignition was observed. However, in the battery q of the comparative example, all 50 cells burst. It is considered that this is because the compression rate of the valve element in the safety valve device exceeded the elastic limit with the rise of the battery temperature and the battery internal pressure in the overcharged state, and the function as the elastic body was lost.

Next, the above-mentioned 5 kinds of batteries of m to q were prepared for each 50 cells, and the results of evaluating the storage stability of the battery under the high temperature and high humidity to low temperature and low humidity environment according to MIL-STD-202F were evaluated ( It shows in Table 5).

[0063]

[Table 5]

From Table 5 the batteries m, n, o according to the present invention
No abnormality was found in the battery q of Comparative Example. However, in the battery p of the comparative example, 31 cells out of 50 cells leaked. This is because the compression rate when arranging the valve body in the safety valve device is lowered, so the safety valve device is hermetically closed (closed).
Could not be secured, and it is considered that leakage occurred.

[0065]

As described above, according to the present invention, the safety valve device can be made thinner, and the valve operating pressure can be stably maintained for a long period of time to ensure reliability. Further, exhaust can be dealt with even when the internal pressure of the battery rises due to a rapid temperature rise such as when the battery is abnormally used, and a sealed battery having high safety can be provided.

[Brief description of drawings]

FIG. 1 is a graph showing experimental results for confirming the effects in Example 1 of the present invention.

FIG. 2 is a graph showing a long-term reliability evaluation result of the valve operating pressure of the safety valve device according to the second embodiment of the present invention.

FIG. 3 is a graph showing an experimental result for confirming the effect in Example 3 of the present invention.

FIG. 4 is a vertical sectional view showing an example of a safety valve device for a sealed battery.

FIG. 5 is a vertical cross-sectional view showing an example of a safety valve device having a thin sealed battery.

[Explanation of symbols]

 1 case 2 sealing plate 2a gas vent hole 3 gasket 5 positive electrode terminal 5a gas exhaust port 6 valve chamber 7 elastic valve body

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Suzuki, 1006 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Toshihisa Hiroshima, 1006, Kadoma, Kadoma City, Osaka Matsushita Electric Industrial

Claims (7)

[Claims] 1. A battery container accommodating a power generating element and a safety valve device for sealing an opening of the battery container, the safety valve device having a plate-like sealing plate having a gas vent hole in a central portion thereof, and the sealing plate. The elastic valve body is disposed above and closes the gas vent hole, and a cap-shaped terminal that locates the valve body in a space forming a valve chamber. The elastic valve body is made of an olefin resin, At least one resin selected from a styrene resin, an amide resin, and a fluorine resin and an ethylene propylene rubber raw material are mixed, and then molded into a predetermined shape and simultaneously crosslinked. Type battery. 2. The elastic valve body comprises an ethylene propylene rubber raw material containing at least one resin selected from an olefin resin, a styrene resin, an amide resin and a fluorine resin having a softening temperature lower than that. The sealed battery according to claim 1, which is incorporated in the inside thereof. 3. The mixing amount of at least one resin selected from olefin resin, styrene resin, amide resin and fluorine resin in the elastic valve body is 5 to 30 relative to ethylene propylene rubber. The sealed battery according to claim 1 or 2, which has a weight percentage. 4. A battery container accommodating a power generating element, and a safety valve device for sealing an opening of the battery container, the safety valve device having a plate-like sealing plate having a gas vent hole in a central portion, and the sealing plate. The elastic valve body is disposed above and closes the gas vent hole, and a cap-shaped terminal that locates the valve body in a space forming a valve chamber. At least one resin selected from the group consisting of resin series, amide series resin, and fluorine series resin and ethylene propylene rubber raw material are mixed and then molded into a predetermined shape and simultaneously cross-linked. Olefin resin, styrene resin,
At least one resin selected from amide-based resins and fluorine-based resins is incorporated therein, and the valve operating pressure is substantially reduced when the battery becomes hot due to plastic deformation due to heating. A sealed battery characterized by: 5. The safety valve device according to claim 5, wherein the valve operating pressure at a temperature of 100 to 120 ° C. is 60% of the valve operating pressure at room temperature.
The sealed battery according to claim 4, wherein the sealed battery is reduced to 20%. 6. A battery container accommodating a power generating element, and a safety valve device for sealing an opening of the battery container, the safety valve device having a plate-like sealing plate having a gas vent hole in a central portion, and the sealing plate. The elastic valve body is disposed above and closes the gas vent hole, and a cap-shaped terminal that locates the valve body in a space forming a valve chamber.
It has a thickness of 0 mm or more and 10 in the thickness direction.
A method for manufacturing a hermetically sealed battery, characterized in that it is compressed by -50% and placed in a valve chamber space. 7. The method for producing a hermetically sealed battery according to claim 6, wherein the elastic valve body is obtained by mixing 5 to 30% by weight of polypropylene in a raw material of ethylene propylene rubber and molding the mixture into a predetermined shape and simultaneously crosslinking the same.