JP2978754B2 - Explosion-proof battery - 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 having an explosion-proof function, and more particularly to a technique for a battery having a high energy density such as a lithium ion secondary battery.

[0002]

2. Description of the Related Art High energy density batteries generally have an explosion-proof function, which includes an internal pressure releasing function, a pressure-sensitive shut-off function, and a temperature-sensitive shut-off function. The internal pressure release function releases gas from the battery to the outside when the pressure inside the battery case rises abnormally to prevent an explosion.The pressure-sensitive shut-off function charges when the pressure inside the battery case rises abnormally. The current or discharge current is interrupted inside the battery to prevent abnormal charging or discharging from continuing, and the temperature-sensitive shut-off function responds to an abnormal rise in temperature inside the battery and reduces the internal resistance of the battery. The charge current or discharge current is narrowed by rapidly rising to prevent the abnormal charging or discharging from continuing.

Many high-energy density lithium ion secondary batteries have an internal pressure release function and a temperature-sensitive shut-off function in addition to a pressure-sensitive shut-off function. , The pressure-sensitive shutoff function is activated to stop charging or discharging, and the internal pressure release function is activated. It is extremely important in designing this type of battery that high-precision, highly reliable explosion-proof functions are realized with a structure that is as compact and mass-producible as possible. It is to make things.

[0004] A typical structure of a battery having an internal pressure releasing function and a pressure-sensitive shut-off function is disclosed in Japanese Patent Application Laid-Open No. 2-288063. This battery is basically composed of a cylindrical metal battery case with a bottom, a power generation element housed in the battery case, and a lid element that closes the opening of the battery case. A blocking function is provided on the lid element. The lid element includes an external terminal plate having a gas vent hole, an intermediate pressure-sensitive plate made of a thin metal plate that is easily bent and broken, and an insulating plate called a lead stripper. The pressure in the battery case acts on the intermediate pressure-sensitive plate, and when the pressure increases, the intermediate pressure-sensitive plate bends outward, and when the pressure exceeds a set pressure, the intermediate pressure-sensitive plate is broken, and gas is released from the gas vent hole of the external terminal plate. .
This is the internal pressure release function.

Further, a lead tab connected to one electrode of the power generating element is welded to a central projection of the intermediate pressure sensing plate through a small hole at the center of the insulating plate. Since the pressure sensitive plate is deformed so as to swell outward, welding of the lead tab to the intermediate pressure sensitive plate is peeled off, and the conductive path leading to the external terminal plate is cut off. This is the pressure-sensitive cutoff function.

In the above-mentioned Japanese Patent Application Laid-Open No. 2-288063, an intermediate pressure-sensitive plate and an insulating plate, which are components of a lid element, are temporarily assembled by an intermediate fitting, and an ultrasonic welding process of the lead tab and the intermediate pressure-sensitive plate is performed. Is easier and more accurate,
In addition, it is devised to facilitate assembly of the lid element and attachment to the battery case. However, mass productivity and assembly accuracy are completely insufficient for the following reasons.

First, there is a problem that the process of welding the lead tab to the intermediate pressure sensing plate and then assembling the lid element is extremely troublesome. That is, the lead tab connected to one electrode of the power generating element housed in the battery case is pulled out of the case, the lead tab is welded to the intermediate pressure sensing plate temporarily assembled with the intermediate fitting body, and then the lead tab is used. An external terminal plate is superimposed on the upper surface of the intermediate pressure-sensitive plate connected to the battery case side, the outer peripheral portion of the intermediate pressure-sensitive plate is caulked to be integrated with the external terminal plate, and a sealing gasket is attached to the outer periphery of these. . This entire operation is a very difficult process to handle, and it is difficult to improve mass productivity.

Also, the work of fitting the central projection of the intermediate pressure-sensitive plate into the small hole of the insulating plate and welding the lead tab to the projection through the small hole is troublesome, and it is difficult to increase the precision. Furthermore, after the lead tab is welded to the central projection of the intermediate pressure-sensitive plate, the outer peripheral portion of the intermediate pressure-sensitive plate is crimped to integrate the external terminal plate. It also acts on the lead tab welding point, and the welding point may come off. Therefore, the welding strength eventually varies.

Further, since the lead tab is generally a ribbon-shaped plate having a width of about 3 mm and has flexibility, when the internal pressure of the battery rises and the intermediate pressure-sensitive plate is deformed, the lead tab becomes smaller with the intermediate fitting body. There is a case where it is dragged into the hole and cannot be reliably separated at a predetermined internal pressure.

As described above, problems such as a decrease in the operation accuracy and reliability of the pressure-sensitive cutoff function occur.

In order to solve such a problem, Japanese Patent Application Laid-Open No. 5-34043 discloses a battery having an explosion-proof function.
In the battery having the explosion-proof function disclosed in Japanese Patent No. 288063, a metal plate is provided in place of the insulating plate, and the metal plate does not have a small hole for welding the lead tab and has only a gas vent hole. A central projection of the intermediate pressure-sensitive plate is welded to the center of the upper surface of the metal plate, and a lead tab is welded to the lower surface thereof. Also, when the welding strength between the central projection of the intermediate pressure-sensitive plate and the metal plate is set to a predetermined value, and the internal pressure of the battery rises and the intermediate pressure-sensitive plate swells to the side opposite to the power generating element and is deformed. In addition, the central projection of the intermediate pressure-sensitive plate and the metal plate are separated according to the set welding strength, so that a conductive path leading to the external terminal plate is cut off.

With the above arrangement, as described above, the step of welding the lead tab to the intermediate pressure-sensitive plate and then assembling the lid element, or inserting the central projection of the intermediate pressure-sensitive plate into the small hole of the insulating plate and projecting through the small hole. The work of welding the lead tab to the part can be eliminated, and the operation accuracy and reliability of the pressure-sensitive shut-off function are improved.

[0013]

However, the batteries having the explosion-proof function as described above have not been satisfactory in terms of the operational accuracy and reliability of the pressure-sensitive shut-off function. That is, in blocking the conductive path leading to the external terminal plate when the internal pressure of the battery rises, the separation between the central projection of the intermediate pressure sensing plate and the metal plate depends on the set welding strength. However, it is very difficult to precisely set the welding strength so as to cut off the conductive path with high accuracy for a predetermined battery internal pressure, and as a result, in the battery having the explosion-proof function as described above, the operation accuracy is not high. Variations cannot be suppressed and sufficient reliability cannot be obtained.

As described above, the welding operation itself while controlling the welding strength so that the welded portion is peeled off at a predetermined internal pressure of the battery is complicated and poor in reproducibility. In order to increase the accuracy, the assembly speed must be reduced, and mass productivity must be sacrificed.

The present invention has been made in view of the above-mentioned conventional problems, and has as its object to provide a battery having an explosion-proof function that enhances the operation accuracy and reliability of the explosion-proof function and also enhances the assemblability and mass productivity. Is to do.

[0016]

In order to achieve the above object, according to the present invention, a bottomed cylindrical battery case, a power generation element housed in the battery case, and one electrode of the power generation element are connected. A battery comprising a lead tab and a lid element which is electrically connected to the lead tab and closes an opening of the battery case, wherein the lid element is relatively rigid and has a relatively large metal terminal plate, and is easily bent and broken. An intermediate pressure-sensitive plate made of a metal plate, an insulating fixing plate, a conductive member consisting of a protrusion and a base protruding upward, and an insulating tubular gasket; and the terminal plate and the fixing plate. A gas vent hole is formed, and the conductive member has the upper surface of the protrusion exposed on the upper surface side of the fixing plate and the lower surface of the base exposed on the lower surface side of the fixing plate. The gas on the inner circumference The fixed plate is fitted into the inner periphery of the gasket, the intermediate pressure-sensitive plate and the terminal plate are laminated on the fixed plate, and the conductive member and the intermediate pressure-sensitive plate are connected to each other by the conductive member. The two protruding portions are connected to each other, and both are electrically connected only at a contact portion including the connection portion, the leading end of the lead tab is connected to the base portion of the conductive member, and the opening portion of the battery case is inside. By being caulked, the gasket is compressed, the battery case is sealed with the lid element, and the conductive member is formed by the intermediate pressure-sensitive plate that swells outward when the inside of the battery case reaches a predetermined internal pressure. The conductive path between the lead tab and the terminal plate is cut off by breaking the periphery of the connecting portion of the projection.

Further, the fixing plate and the gasket may be formed as a single component to form a gasket plate.

Preferably, the conductive member is embedded in the fixed plate and integrated.

Preferably, a retaining ring is provided on the outer periphery of the gasket, and a peripheral portion of a lower end of the gasket is pressed against the fixing plate by the retaining ring.

More preferably, the projecting portion of the conductive member is formed in a cylindrical shape, or is formed by bending a rectangular plate into a projecting shape.

It is preferable that the material of the fixing plate is plastic having a deflection temperature under load of 200 ° C. or more.

Here, the deflection temperature under load is defined as ASTM (Am
erican Society for Testing and Materials) Standard A
It indicates the temperature at which a predetermined amount of deflection occurs under a load of 1.82 MPa, which is defined by STM D648.

The pressure in the battery case acts on the intermediate pressure-sensitive plate through a gas vent hole of the fixed plate or the gasket plate. When the internal pressure rises abnormally, the intermediate pressure-sensitive plate is deformed so as to expand outward, and the deformed intermediate pressure-sensitive plate breaks the periphery of the connection portion of the protrusion of the conductive member, so that the lead tab and the terminal plate are broken. Is interrupted (pressure-sensitive shut-off function). When the intermediate pressure sensing plate is further deformed, it is eventually broken, and the gas in the battery case is released to the outside (internal pressure releasing function).

In order to cut off the conductive path between the lead tab and the terminal plate, a structure is adopted in which the periphery of the connecting portion of the projection of the conductive member is broken without separating the welding point between the members. In addition, it is not necessary to set the connection strength with high precision, and it is sufficient to simply perform a strong welding.
That is, since the cutoff accuracy depends only on the material and dimensions of the conductive member, it is not necessary to perform high-precision control of the connection strength at the time of manufacture only by defining these at the time of design, and the cutoff accuracy of the conductive path with respect to the internal pressure. Can be easily set. Therefore, the conduction path can be cut off with high accuracy with respect to an increase in the internal pressure. In addition, since the connection strength does not need to be high precision, assembly becomes easy.

In the case where the fixing plate and the gasket are formed as one component to form the gasket plate, the number of components can be reduced.

When a retaining ring is provided on the outer periphery of the gasket, the lower peripheral portion of the gasket is pressed against the fixing plate by the retaining ring, so that the fixing plate is securely held by the gasket. Therefore, even if an unexpected external vibration or impact is applied, the fixing plate can be reliably prevented from coming off or damaging the connecting portion of the conductive member, so that the operation of blocking the conductive path against the increase in the internal pressure can be performed more reliably.

In the case where the projecting portion of the conductive member is formed by bending a rectangular plate into a projecting shape, it is only necessary to bend the rectangular plate in forming the conductive member, so that the processing is simple. Become.

The material of the fixed plate is subjected to a load deflection temperature of 200 ° C.
In the case of using the above-mentioned plastic, it is possible to reliably prevent the fixing plate from softening even if the battery internal temperature abnormally rises to 100 ° C., for example, due to overcharging in a high-temperature atmosphere.

Accordingly, when the predetermined pressure of the conductive path is reached in a high-temperature atmosphere, the fixing plate is softened and the intermediate pressure-sensitive plate is deformed outwardly together with the conductive member welded thereto. It is possible to reliably prevent the accuracy of the pressure-sensitive shut-off function from being reduced due to the following of the fixed plate.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an essential structure of a battery having an explosion-proof function including a temperature-sensitive shut-off function according to a first embodiment of the present invention.
Shown in The basic configuration of this battery is as follows: a bottomed cylindrical metal battery case 1; a power generating element (not shown) housed in the battery case 1; a lead tab 2 connected to one electrode of the power generating element; A lid element electrically connected to the lead tab 2 and closing the opening of the battery case 1.

The cover element includes a metal terminal plate 3 having relatively large rigidity, a temperature-sensitive resistance element (PCT element) 4 having a positive characteristic formed in a ring shape, and an intermediate pressure-sensitive plate 5 made of a flexible metal plate. And an insulating fixing plate 6 and a protruding portion 7 protruding upward.
a and a base (flange) 7b, and an insulating tubular gasket 8. The terminal plate 3 and the fixing plate 6 are formed with gas vent holes 3a and 6a, respectively, and the intermediate pressure sensing plate 5 is formed with a thin portion 5a so as to break at a predetermined internal pressure. The conductive member 7 is composed of a projection 7a having the center of a circular plate protruding in a truncated cone shape and a base 7b formed of the outer periphery thereof. As shown in FIGS. 3 and 4, the conductive member 7 is embedded in the fixed plate 6 by insert molding. Integrated. The upper surface of the protrusion 7a is exposed on the upper surface side of the fixed plate 6, and the lower surface of the base 7b is exposed on the lower surface side of the fixed plate 6.

The gasket 8 includes a fixed plate 6 and an intermediate pressure-sensitive plate 5.
And step portions 8a and 8b for mounting the respective components are formed.

The procedure for assembling these lid elements into the opening of the battery case 1 will be described. First, the conductive member 7 embedded in the fixing plate 6 and the intermediate pressure-sensitive plate 5 are ultrasonically welded in advance.

At this time, the upper surface of the projecting portion 7a of the conductive member 7 is locally welded to the center of the lower surface of the intermediate pressure-sensitive plate 5, and the welding strength of the welding point 7 is maintained even if the intermediate pressure-sensitive plate 5 is deformed.
It is set to be sufficiently strong so that it does not peel at c.

On the other hand, a gasket 8 is fitted into the upper surface of the stepped portion 1a which has been previously reduced in diameter by beading into the opening of the battery case 1.

Then, the lead tab 2 is ultrasonically welded to the lower surface of the base 7b of the conductive member 7, and the fixing plate 6 is fitted on the inner peripheral surface of the gasket 8 so as to be pressed against the upper surface of the step 8a. The intermediate pressure-sensitive plate 5 is fitted so as to be pressed against the upper surface of the portion 8b.

Next, the temperature-sensitive resistance element 4 and the terminal plate 3 are sequentially fitted on the inner peripheral surface of the gasket 8, and finally, the gasket 8 is compressed by caulking the opening of the battery case 1 inward. Seal 1

When caulking the opening of the battery case 1, a force is not applied in the radial direction but only in the direction of the central axis of the cylinder. As a result, no harmful stress is applied to the welding point 7c between the intermediate pressure-sensitive plate 5 and the conductive member 7, the welding strength is stabilized, and the operation characteristics of the pressure-sensitive shut-off function are stabilized.

One electrode of the power generating element is connected to the conductive member 7 by the lead tab 2, and the conductive member 7 is connected to the intermediate pressure-sensitive plate 5 at the welding point 7c on the upper surface of the projection 7a.
Is connected to the terminal plate 3 via the temperature-sensitive resistance element 4.
A load circuit is connected to the terminal plate 3.

In using the battery having the above configuration,
When gas is generated inside due to overdischarge, overcharge, or the like, the gas pressure in the battery case 1 acts on the intermediate pressure-sensitive plate 5 through the gas vent hole 6 a of the fixed plate 6. If the internal pressure rises abnormally,
As shown in FIG. 2, the intermediate pressure-sensitive plate 5 is deformed so as to expand outward, and the periphery of the conductive member 7 around the welding point 7c is broken.
As a result, the charging or discharging current circuit connected to the terminal plate 3 is cut off (pressure-sensitive cut-off function).

When the intermediate pressure-sensitive plate 5 is further deformed, the thin portion 5a is eventually broken, and the gas in the battery case 1 is released to the outside (internal pressure releasing function). When a large current flows due to a short circuit in an external circuit connected to the battery and the temperature of the battery rises abnormally, the temperature-sensitive resistance element 4 inserted in the charging or discharging current circuit connected to the terminal plate 3 Increase the resistance value of the battery and decrease the charge or discharge current (temperature-sensitive shut-off function).

If the temperature-sensitive resistor element 4 is eliminated and the terminal plate 3 is directly stacked on the intermediate pressure-sensitive plate 5, an explosion-proof function having no temperature-sensitive shut-off function can be obtained.

When the conductive path between the lead tab 2 and the terminal plate 3 is cut off, the welding point 7c between the intermediate pressure sensing plate 5 and the conductive member 7 is not peeled off, but the periphery of the conductive member 7 around the welding point 7c is broken. Because of this configuration, it is not necessary to set the welding strength with high precision, and it is sufficient to simply perform welding. That is, since the breaking accuracy depends only on the material and the size and shape of the conductive member, it is not necessary to perform high-precision control of the welding strength at the time of manufacturing only by defining these at the time of design, and the breaking accuracy of the conductive path with respect to the internal pressure is easily improved. Can be set with high reliability. Therefore, the conduction path can be cut off with high accuracy with respect to an increase in the internal pressure, whereby the reliability of the pressure-sensitive cut-off function is improved and the safety is improved. Further, since it is not necessary to make the welding strength high, assembly is facilitated and mass productivity is improved.

Here, in order to confirm the shut-off characteristic of the pressure-sensitive shut-off function of the battery according to the present embodiment, the above-mentioned conventional Japanese Patent Application Laid-Open No. Hei 5
The breaking operation pressure with respect to the internal pressure of the battery was measured by comparing the battery of the present invention with that of this example as a comparative example.

In measuring the working pressure, a thermostat, a pressurizing pump, and a tester are prepared as working pressure measuring devices. The constant temperature bath has a measuring battery inserted therein and keeps its internal temperature, that is, the temperature of the fixed plate 6, at a constant level, and the pressurizing pump keeps the inside of the battery at a predetermined pressure. A pipe extends from this pressurizing pump,
Pressure can be applied to the inside of the battery through this pipe. The pipe is provided with a pressure gauge so that the pressure applied through the pipe can be measured. In addition, the tester connects each of the measuring terminals extending from the tester to the terminal plate 3 and the conductive member 7 of the measuring battery, and monitors the conduction state between the two to thereby determine the welding point 7c of the conductive member 7. This is for confirming whether or not the periphery has been broken and the conductive path has been interrupted.

Specifically, 50 batteries were prepared for each of the present embodiment and the comparative example. For measurement, a hole having a diameter of 3 mm was formed in the bottom of the battery case, and a pipe capable of introducing a predetermined gas pressure was used. Insert into the hole from the outside and use an O-ring to prevent gas leakage, and use a caulking jig to maintain the airtightness between the pipe and the case hole. Then, the number of broken conductive members for each internal pressure value of these batteries, that is, the number of interrupted conductive paths in the batteries was examined.

As a result, as shown in Table 1, in the comparative example of the related art, the breaking operation pressure was 6 to ² around the 14 to 15 kgf / cm ^2.
Whereas the varied over a wide range of 5 kgf / cm ^2, in the present embodiment is accommodated in a narrow range of 12~17Kgf / cm ² with 14~15Kgf / cm ² to more than 60% is concentrated, the It was confirmed that the pressure-sensitive shut-off function of the batteries of Examples was highly accurate and extremely excellent. The intermediate pressure plate 5
When the internal pressure reaches about 30 kgf / cm ² , the thin portion 5 a is broken.

[0048]

[Table 1] Here, the material of the fixing plate 6 will be described. This material is used in order to prevent the battery from being stored in an environment of about 80 ° C or to be exposed to a high temperature of about 100 ° C for a relatively short period of time without substantially impairing its function. In order to satisfy conditions such as being placed on a part that comes in contact with liquid and not easily deformed even when some external force is applied such as during assembly, heat resistant materials such as polybutylene terephthalate, polyphenylene sulfide, or polytetrafluoroethylene are used. It is possible to use a thermoplastic resin having excellent rigidity and excellent electrolytic solution resistance and having high rigidity, or a thermosetting resin such as a phenyl resin such as Bakelite or an epoxy resin.

Further, as the material of the fixing plate 6, it is particularly desirable to use a plastic having a deflection temperature under load of 200 ° C. or more in addition to the above-mentioned conditions. Specific examples include polybutylene terephthalate containing 30% by weight of glass fiber, polyphenylene sulfide containing 40% by weight of glass fiber, and liquid crystal polymer containing 30% by weight of glass fiber.

The reason why such a material is used for the fixing plate 6 is that, for example, when the battery is overcharged in a high-temperature atmosphere, even if the battery internal temperature rises abnormally and reaches 100 ° C., for example, the fixing plate 6 This is for surely preventing softening. That is, when the battery internal temperature rises abnormally and the battery internal pressure rises abnormally and reaches the cutoff pressure of the predetermined conductive path, if the fixing plate 6 is softened, the intermediate pressure-sensitive plate 5 moves outward. The fixing plate 6 follows the deformation of the fixing plate 6 together with the conductive member 7 welded thereto, and flexes outward. Therefore, at the predetermined cutoff pressure, the periphery of the conductive member 7 around the welding point 7c does not break, so that the conductive path cannot be cut off. Then, when the internal pressure further abnormally rises, the conductive path can be finally cut off, and there is a possibility that an error occurs in the cutoff pressure of the conductive path and the accuracy of the pressure-sensitive cutoff function is reduced.

Therefore, as described above, by using plastic having a deflection temperature under load of 200 ° C. or more as the material of the fixing plate 6, the above-mentioned possibility can be eliminated, and erroneous operations such as overcharging in a severe temperature environment can be avoided. Even for use, it is possible to realize a reliable cutoff characteristic of the conductive path against an increase in internal pressure.

Here, in order to confirm the effectiveness of using a plastic material having a deflection temperature under load of 200 ° C. or more as a material of the fixing plate 6, as shown in Table 2, the fixing plates 6 having different deflection temperatures under load were used. For the battery of this example using, the operating pressure of the current interruption function was examined while changing the temperature.

[0053]

[Table 2] Specifically, fixation plates of five types of materials are prepared, and polypropylene and polypropylene terephthalate having a deflection temperature under load of less than 200 ° C. (these materials are injection molded.)
(Easy and inexpensive), polybutylene terephthalate containing 30% by weight of glass fiber having a deflection temperature under load of 200 ° C. or more, polyphenylene sulfide containing 40% by weight of glass fiber, and liquid crystal polymer containing 30% by weight of glass fiber were used.

As the measuring battery for measuring the operating pressure, in the battery of the configuration of the present embodiment, the power generating element is not accommodated, and the lid element is kept attached to the opening thereof. In addition, a battery case 1 in which an insertion hole having a diameter of 3 mm is formed in the bottom portion is used.

Then, ten measuring batteries each having the fixed plate 6 of each material incorporated therein were prepared, and the above-mentioned working pressure measuring device was used to prepare 20 ° C., 45 ° C., 60 ° C., 10 ° C.
The breaking operation pressure of the conductive path was measured in the atmosphere at each temperature of 0 ° C. For details, place the battery for measurement in the thermostat,
A pipe extending from the pressurizing pump is inserted into the insertion hole at the bottom of the battery case 1 in an airtight state. Then, each measurement terminal from the tester is connected to the terminal of the battery and the conductive member 7, respectively. In this state, the inside of the thermostat was maintained at each of the above-mentioned ambient temperatures, and the internal pressure of the battery was increased. At this time, since the inside of the measurement battery is in an empty state in which the power generation element is not housed, the temperature of the fixed plate 6 incorporated in the measurement battery is changed to the atmosphere inside the thermostat after a predetermined time has elapsed. It will be the same as the temperature.

As a result, as shown in Table 2, at an ambient temperature of 20 ° C., the conductive path was interrupted when the internal pressure of the battery incorporating all five types of fixing plates was 14 or 15 kg / cm ² on average. In particular, when the deflection temperature under load of the present invention was 200 ° C. or higher, all the shut-off operating pressures were 14 kg / cm ² and the standard deviation thereof was 1.1 or 1.2, exhibiting excellent characteristics. The shut-off operating pressure is 14 to
A range of 18 kg / cm ² is desirable.

In a battery incorporating a polypropylene fixing plate having a deflection temperature under load of less than 200 ° C. at an ambient temperature of 45 ° C., the shut-off operating pressure is 20 kg / cm.
^{In addition to 2} exceeding 18 kg / cm ² , the standard deviation is 5.2 and the variation is large. For a battery incorporating a fixing plate made of polybutylene terephthalate having a deflection temperature under load of less than 200 ° C., the shut-off operating pressure is 18 Kg / cm ² , which is the upper limit of the desirable range, but the standard deviation is 5.0 and its variation. Is getting bigger. On the other hand, with respect to the load deflection temperature of the present invention of 200 ° C. or more, the shut-off operating pressure is 14 or 15 kg / cm ² and the standard deviation thereof does not vary from 1.0 to 1.2. It showed very good properties.

At an ambient temperature of 60 ° C., in the battery incorporating the fixing plate having a deflection temperature under load of less than 200 ° C., the conduction path was not interrupted. This is because the fixed plate softens at approximately 60 ° C. and the intermediate pressure-sensitive plate 5
It is conceivable that the fixing plate 6 was bent outward along with the conductive member 7 welded to the outwardly deforming movement. On the other hand, when the deflection temperature under load of the present invention is 200 ° C. or more, the shut-off operating pressure is 14 or 15 Kg / cm ² and the standard deviation thereof does not vary from 1.0 to 1.3. It showed very good properties.

Further, at an ambient temperature of 100 ° C., the deflection temperature under load is 200 ° C., as in the case of 60 ° C.
In the battery incorporating the smaller fixing plate, the conduction path was not interrupted. On the other hand, when the deflection temperature under load of the present invention is 200 ° C. or more, the shut-off operating pressure falls within a desirable range of 14 to 18 kg / cm ² and the standard deviation thereof varies to 2.2 or less. There were no very good characteristics. In particular, in the case of polyphenylene sulfide containing 40% by weight of glass fiber, the cut-off operating pressure is operated at a low value of 14 kg / cm ^2, and its standard deviation is almost not varied to 1.3, so that it is extremely excellent. The characteristics were shown.

Therefore, when the material of the fixing plate is plastic having a deflection temperature under load of 200 ° C. or more, it is possible to realize a reliable cutoff characteristic of the conductive path without variation even when the internal pressure is abnormally increased in a high temperature atmosphere.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6 (a) and 6 (b). This differs from the first embodiment described above in the following points. That is, a retaining ring 9 is provided as a separate member, and this is fitted around the lower end of the gasket 8 so that the lower peripheral portion of the gasket 8 is
Is pressed against the fixing plate 6.

In the battery of this embodiment, the components constituting the lid element operate in the same manner as in the first embodiment, and thus have the same explosion-proof function. However, they receive unexpected external vibrations and shocks. Even if the fixing plate 6 comes off the gasket 8 or the conductive member 7
Can be reliably prevented from damaging the welding point 7c, so that the operation of interrupting the conductive path with respect to an increase in the internal pressure can be performed more reliably.

The cross-sectional shape of the holding ring 9 is substantially L-shaped as shown in FIG. 5, or a projection 8c is formed by projecting the lower outer end of the gasket 8 outward as shown in FIG. 6 to fit the retaining ring 9 having a rectangular cross section.
As shown in (b), a fitting projection 8d is formed on the outer periphery of the lower outer end of the gasket 8, and a groove 9a fitted to the fitting projection 8d is formed in the holding ring 9 so that the two fit together. Various modifications are possible.

In this embodiment, as shown in FIG.
The gasket 8 is provided with an inwardly projecting portion 8e so as to sandwich the peripheral edge of the fixing plate 6 up and down so that the fixing plate 6 can be held more firmly. At this time, the protrusion 7a of the conductive member 7 is protruded toward the opening of the battery case 1 by the thickness of the protrusion 8e, and is welded to the intermediate pressure-sensitive plate 5.

In the present embodiment, the center of the fixing plate 6 is opened, and the conductive member 7 is inserted and fitted therein. However, the present invention is not limited to this, and as in the first embodiment shown in FIG. Alternatively, the conductive member 7 may be embedded in the fixing plate 6 by insert molding and integrated therewith.

Next, a third embodiment of the present invention will be described with reference to FIG. This differs from the first embodiment described above in the following points. That is, the gasket plate 10 is formed by integrating the fixing plate 6 and the gasket 8 of the first embodiment into one piece. With this configuration, the number of parts can be reduced, the assemblability can be improved, and the cost can be reduced.

In the battery of this embodiment, the components constituting the lid element operate in the same manner as in the first embodiment, and thus have the same explosion-proof function. To confirm this, the cutoff operating pressure with respect to the internal pressure was measured as in the case of the first embodiment described above.

As a result, as shown in Table 3, in the comparative example of the related art, the breaking operation pressure was 6 to ² around 14 to 15 kgf / cm ^2.
Whereas the varied over a wide range of 5 kgf / cm ^2, and falls within a narrow range of 12~17Kgf / cm ² with more than 50% in 14~15Kgf / cm ² is concentrated in this embodiment, It was confirmed that the pressure-sensitive shut-off function of the battery of this example was highly accurate and extremely excellent. As in the first embodiment, when the internal pressure of the intermediate pressure sensing plate 5 reaches about 30 kgf / cm ² , the thin portion 5 a is broken.

[0069]

[Table 3] The first to third embodiments of the present invention have been described above. Instead of the conductive member 7 in these embodiments, as shown in FIGS. The conductive member 7 formed with 7a may be used. In this case, since it is only necessary to bend a rectangular plate when forming the conductive member 7, the processing is simplified, the mass productivity is improved, and the cost of this component can be reduced.

In addition to the above, conductive members 7 of various sizes and shapes and materials can be applied. For example, as shown in FIG.
A protrusion 7 d may be formed on the upper surface of the protrusion 7 a of the rectangular plate 7, and the tip of the protrusion 7 d may be used as a welding point 7 c with the intermediate pressure-sensitive plate 5.

Also in the above case, the welding point 7c is sufficiently firmly welded so that the welding point 7c between the intermediate pressure sensing plate 5 and the conductive member 7 is peeled off when the internal pressure rises and the conductive path is cut off. In this configuration, the periphery (7d) of the conductive member 7 around the welding point 7c is broken.

The present invention is not limited to the cylindrical battery as in the first to third embodiments described above, but can be applied to a rectangular lithium secondary battery or the like by making the planar outer shape of each component of the lid element rectangular. By making each of these parts rectangular, it is easy to perform molding, and the yield is improved and the cost is reduced.

[0073]

As described above in detail, in the battery having the explosion-proof function of the present invention, the connection strength can be controlled with high accuracy during the production by simply determining the material and dimensions of the conductive member at the time of design. And it is possible to easily and accurately set the cutoff accuracy of the conductive path with respect to the internal pressure. Therefore, the conduction path can be cut off with high accuracy against an increase in the internal pressure, and the reliability of the pressure-sensitive cut-off function is improved, and the safety is improved. In addition, since it is not necessary to make the connection strength high, assembly is easy and mass productivity is improved.

When the fixing plate and the gasket are formed as one component to form the gasket plate, the number of components can be reduced, so that the assemblability can be improved and the cost can be reduced.

When the retaining ring is provided on the outer periphery of the gasket, it is possible to prevent the fixing plate from coming off or damaging the connecting portion of the conductive member even if an unexpected external vibration or impact is applied. The operation of blocking the conductive path can be performed more reliably, the reliability of the pressure-sensitive blocking function is improved, and the safety is further improved.

When the protruding portion of the conductive member is formed by bending a rectangular plate into a protruding shape, the processing is simplified, the mass productivity is improved, and the cost can be reduced.

The material of the fixing plate is subjected to a load deflection temperature of 200 ° C.
When the above plastic is used, it is possible to reliably prevent the fixing plate from softening even when the battery internal temperature rises abnormally and reaches 100 ° C., for example. For this reason, even in a severe environment such as overcharging in a high-temperature atmosphere, it is possible to realize a reliable cutoff characteristic of a conductive path that does not vary even when the internal pressure is abnormally increased.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a battery having an explosion-proof function according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of a main part showing a state in which a pressure-sensitive shut-off function operates in the battery of FIG.

FIG. 3 is a plan view of a fixing plate in which a conductive member according to a first embodiment of the present invention is embedded.

FIG. 4 is a cross-sectional view taken along the line IV-O-IV of the fixing plate of FIG. 3;

FIG. 5 is a sectional view of a main part of a battery having an explosion-proof function according to a second embodiment of the present invention.

FIG. 6 is a longitudinal sectional view of a main part of a retaining ring fitted to a gasket according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a main part of a battery having an explosion-proof function according to a third embodiment of the present invention.

FIG. 8 is a perspective view showing another embodiment of the conductive member of the present invention.

9 is a plan view showing a state where the conductive member of FIG. 8 is fitted or embedded in a fixing plate.

FIG. 10 is a sectional view showing another embodiment of the conductive member of the present invention and a fixing plate welded thereto.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 battery case 2 lead tab 3 terminal plate 4 temperature-sensitive resistance element 5 intermediate pressure-sensitive plate 6 fixing plate 7 conductive member 7 a protrusion 7 b base 7 c welded portion (connection portion) 8 gasket 9 retaining ring 10 gasket plate

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takuji Ogawa 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Masahiro Tamai 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. (72) Keiji Fukuhara, Inventor 5-36-11 Shimbashi, Minato-ku, Tokyo Inside Fuji Electric Chemical Co., Ltd. Masatake Nishio, 5-36-11, Shimbashi, Minato-ku, Tokyo No. Fuji Electric Chemical Co., Ltd. (72) Tomoya Murata Inventor 5-36-11 Shimbashi, Minato-ku, Tokyo Fuji Electric Chemical Co., Ltd. (56) References JP-A-7-192712 (JP, A) Kaihei 6-231743 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01M 2 / 12,2 / 34

Claims (6)

(57) [Claims] 1. A battery case (1) having a bottomed cylindrical shape, a power generating element housed in the battery case (1), a lead tab (2) connected to one electrode of the power generating element, and the lead tab. A battery element comprising a cover element electrically connected to (2) and closing an opening of the battery case (1), wherein the cover element comprises a relatively rigid metal terminal plate (3); Intermediate pressure-sensitive plate (5) made of a metal plate that easily bends and breaks
And an insulating fixing plate (6), and a protruding portion (7
a) a conductive member (7) comprising a) and a base (7b), and an insulating tubular gasket (8);
And the fixing plate (6) has a gas vent hole,
In the conductive member (7), the upper surface of the projection (7a) is exposed on the upper surface of the fixing plate (6), and the lower surface of the base (7b) is exposed on the lower surface of the fixing plate (6). Case (1)
The gasket (8) is fitted into the inner periphery of the opening of the gasket (8), the fixing plate (6) is fitted into the inner periphery of the gasket (8), and the intermediate pressure-sensitive plate (5) is placed on the fixing plate (6). ) And a terminal plate (3) are laminated, and the conductive member (7) and the intermediate pressure-sensitive plate (5) are connected to each other by the protrusion (7a) of the conductive member (7) and the connection portion is formed. Only the contact portion including (7c) is conductive, the leading end of the lead tab (2) is connected to the base (7b) of the conductive member (7), and the opening of the battery case (1). Is caulked inward, whereby the gasket (8) is compressed and the battery case (1) is sealed with the lid element. When the inside of the battery case (1) reaches a predetermined internal pressure, it becomes outward. The bulged intermediate pressure-sensitive plate (5) surrounds the connection (7c) of the projection (7a) of the conductive member (7). There battery having explosion-proof features, characterized by comprising as conductive path of the lead tab and (2) the terminal plate (3) is interrupted by breaking. 2. A battery case (1) having a bottomed cylindrical shape, a power generating element housed in the battery case (1), a lead tab (2) connected to one electrode of the power generating element, and the lead tab. A battery element comprising a cover element electrically connected to (2) and closing an opening of the battery case (1), wherein the cover element comprises a relatively rigid metal terminal plate (3); Intermediate pressure-sensitive plate (5) made of a metal plate that easily bends and breaks
And a conductive member (7) consisting of a protrusion (7a) and a base (7b) projecting upward, and an insulating gasket plate (10) having an outer peripheral end erected upward. The plate (3) and the gasket plate (10) are provided with gas vent holes, and the conductive member (7) is provided with the gasket plate (1).
0), the upper surface of the projection (7a) is exposed on the upper surface side, and the lower surface of the base (7b) is exposed on the lower surface side of the gasket plate (10), and the gasket plate (10) is connected to the battery case (1). The intermediate pressure-sensitive plate (5) and the terminal plate (3) are laminated on the gasket plate (10), and the conductive member (7) and the intermediate pressure-sensitive plate (5) are laminated on the gasket plate (10). ) Means the connecting portion (7c) of the projection (7a) of the conductive member (7).
And the two are electrically connected only at a contact portion including the connection portion, and the leading end of the lead tab (2) is connected to the base (7b) of the conductive member (7); By caulking the opening of (1) inward, the outer peripheral end of the gasket plate (10) is compressed, and the battery case (1) is sealed with the lid element. The periphery of the connection (7c) of the projection (7a) of the conductive member (7) is broken by the intermediate pressure-sensitive plate (5) bulged outward when the inside reaches a predetermined internal pressure. A battery having an explosion-proof function, wherein a conductive path between a lead tab (2) and a terminal plate (3) is cut off. 3. The fixing device according to claim 1, wherein the conductive member is provided on the fixing plate.
The battery having an explosion-proof function according to claim 1, wherein the battery is embedded and integrated in the battery. 4. A holding ring (9) is provided on the outer periphery of the gasket (8), and a lower peripheral portion of the gasket (8) is pressed against the fixing plate (6) by the holding ring (9). The battery having an explosion-proof function according to claim 1 or 3. 5. The projection (7a) of the conductive member (7).
The battery having an explosion-proof function according to any one of claims 1 to 4, wherein the battery is formed in a cylindrical shape or a rectangular plate is bent in a protruding shape. 6. The battery having an explosion-proof function according to claim 1, wherein the material of the fixing plate (6) is a plastic having a deflection temperature under load of 200 ° C. or higher.