JP2970340B2 - Explosion-proof sealing plate for sealed batteries - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an explosion-proof sealing plate used for sealing a battery having a high energy density such as a sealed battery, particularly a lithium secondary battery.

[0002]

2. Description of the Related Art In recent years, portable and cordless electronic devices such as AV devices and personal computers have been rapidly advanced, and various types of high-capacity alkaline storage batteries or lithium secondary batteries have been used as power sources for driving these devices. Non-aqueous secondary batteries such as those described above have high expectations as sealed batteries having high energy density and excellent load characteristics. However, in sealed batteries, due to failure of equipment including the charger or misuse, gas is abnormally generated in the battery and the internal pressure becomes excessive,
The battery could explode or damage the equipment used. Therefore, in general, when the battery internal pressure exceeds the set value,
An explosion-proof safety device is added to prevent gas explosion by discharging gas. Generally, a return-type explosion-proof sealing plate in which a valve hole provided in an inner lid plate of a sealing plate is pressed and closed with an elastic valve body and opened and closed at a predetermined pressure, or an inner lid plate provided with a thin portion (For example, Japanese Utility Model Application Laid-Open No. 59-61465), or as shown in FIG. 16, a thin pierceable metal diaphragm (Japanese Utility Model Application Laid-Open No. 54-137734), or a laminate sheet of metal and synthetic resin (real When the internal pressure of the battery rises above a predetermined level, the thin plate-shaped valve body 42a is bent as shown by a dotted line 42b. Then, a non-returnable explosion-proof sealing plate is used, which is broken by the blade projection 43 to discharge gas. Both are used in a sealed alkaline storage battery system, and the latter is mainly used in a non-aqueous secondary battery system in which an organic solvent is required for an electrolyte and high sealing performance is required.

However, when the above-described sealed secondary battery having a high energy density is used, if the battery is charged / discharged or excessively short-circuited with an excessive voltage / current due to the trouble of the above-described equipment, the energy density is reduced. In these high batteries, the temperature rises sharply and gas is likely to be generated in large quantities,
Even when the explosion-proof sealing plate is provided, the generated gas or electrolyte vapor cannot be exhausted completely, which may lead to battery rupture. Among the above high energy density batteries, non-aqueous secondary batteries, in particular, a carbon material or lithium for the negative electrode, a lithium-containing metal oxide (eg, LiCoO ₂ ) or a metal oxide for the positive electrode, and an organic A lithium secondary battery using a solvent has such a large danger, and the sealing portion may be damaged or the battery may be ruptured due to overcharge, excessive current charge, external short circuit, or the like.

As one of measures against the above problem, as seen in a cylindrical lithium primary battery used as a power supply for driving a camera or the like, a sealing plate or a sealing body of a battery provided with the above-mentioned thin valve element is provided. For example, Japanese Utility Model Laid-Open No. 4-46359,
As disclosed in U.S. Pat. No. 4,855,195 or Japanese Patent Application Laid-Open No. 2-207450 (U.S. Pat. No. 4,971,867), a thin ring-shaped or flat PTC element (PTC element) is disclosed.
C = abbreviation of Positive Temperature Coefficient) between the external terminal plate and the cover plate. This PTC
The element is a positive temperature coefficient resistance element whose electrical resistance value increases by orders of magnitude when exceeding a predetermined temperature range due to the flow of a current equal to or greater than a set value, for example, from Raychem under the product name of `` Polyswitch '' Some are commercially available.

When the PTC element is built in as described above,
For example, when applied to a battery having a diameter of 14 to 17 mm, the PTC
When a large current of about 2.5 to 4 amperes (hereinafter referred to as A) or more flows, the PTC element reaches an operating temperature in a short time and the resistance value increases, depending on the configuration conditions of the element. Is greatly reduced and maintained at about 50 to 200 mA. Therefore, remarkable damage to the battery due to an external short circuit or erroneous use with an excessive current can be prevented. However, in the above-mentioned lithium secondary battery, when an operation such as overcharge without control due to a charger failure or the like, reverse charge, multiple series overdischarge, or the like is performed, the current value is equal to or less than the operating current of the PTC element. Also, the safety valve current exceeds the allowable current, the internal pressure of the battery rises, and the break valve often operates.However, if the current continues to flow through the battery, the decomposition of the electrolyte and the active material may occur. In many cases, the battery temperature rises sharply, resulting in ignition or explosive damage. Even if a safety mechanism in which a PTC element is added to a break valve is installed, this problem remains. As described above, in order to prevent a phenomenon that an excessive amount of gas or vapor is generated due to an abnormal reaction caused by continuing unsuitable power supply to the battery and the battery is destroyed, the battery internal pressure is detected and the power supply is performed. It is a reliable means to completely cut off the current, and several proposals have been made for a battery or an electrolytic capacitor having a similar structure to a battery.
Next, an example is shown.

US Pat. No. 4,992,344 or 4,937,153
In the case of a double-sealed battery such as an alkaline manganese dry battery, an external terminal plate is contacted and fixed to the bottom of the inner can containing the power generating element with an outer case or the like to conduct electricity. When a large amount of gas is generated inside the inner can by energization or the like and the bottom surface of the inner can expands and deforms outward, the contact with the external terminal plate is cut off and the current is interrupted. This is to prevent battery damage and the like. In the double can sealing method, a ring-shaped inverting spring contact piece whose outer peripheral edge is always warped upward is inserted between the external terminal plate and the inner can bottom to make contact conduction, and the inner can bottom expands. When it is deformed, the pushing-up pressure causes the reversing spring contact piece to be reversed and the contact to be broken, thereby interrupting the current (US Pat. No. 4,028,478).

As shown in US Pat. Nos. 3,617,386 and 5,026,615, an insulating and flexible diaphragm (resin) having a contact terminal at the center (one electrode lead plate is connected to the back side). The battery container is sealed by a sealing body) and a cap-shaped external terminal plate disposed so as to form a space outside thereof, and an elastic metal contact with both ends warped outward in the space. A structure in which a plate (switch spring) is inserted so that the contact terminal and the external terminal plate are always in contact with each other, or the above-mentioned structure has a contact terminal in the center as a diaphragm and a current collector for one electrode. It is made of a thin metal plate that also serves as a structure, and an annular insulating ring is provided outside thereof. When the gas pressure in the battery rises, the diaphragm expands and deforms outward and the elastic metal Flat contact plate Deformed, there is a proposal to cut off the current turned down the contact conduction.

In addition, in the lithium-sulfur oxide primary battery, in addition to a reset valve mechanism for exhausting gas at a predetermined pressure inside the sealing body, a conductive tube disposed at the center of the electrode group and connected to the positive electrode cap terminal. The lower end is brought into contact with a positive electrode lead contact provided insulated on the inner surface of the bottom plate of the battery container to form a conduction circuit, and when the pressure inside the battery rises abnormally, the bottom plate of the battery container expands and deforms outward, and Separate the contact part,
Some interrupt the conducting circuit (US Pat. No. 3,939,011).
issue). As a method different from the above, a pin-shaped lever (projection)
An elastic metal diaphragm provided at the center of the outer surface side is used as an inner lid, and an upper surface thereof is covered with an external terminal plate provided with a hole through which the lever is provided to form a sealing body. When using a battery that has been used, use a battery holder equipped with an external switch such as a micro switch as the battery holder of the device or charger. If the pressure inside the battery rises due to abnormal energization, the diaphragm expands outward. At the same time, the pin-shaped lever protrudes from the outer surface of the external terminal board,
There is a plan to turn on the external switch to cut off the current (US Pat. No. 3,622,397).

On the other hand, in an electrolytic capacitor as well, as a means for preventing rupture damage due to abnormal gas generation during energization, the lead pieces of both electrodes connected to the external terminals provided on the sealing lid are bent outward by an increase in internal pressure. A method has been proposed in which a current is cut off by the tension of a sealing lid to be cut off.

In one embodiment, the other end of the terminal rod, one end of which is fixed to an external terminal provided insulated on the sealing lid, is led out through a through hole of a rigid blocking plate fixed in the battery container. ,
A structure in which a lead plate of a capacitor element is fixed to the end by welding or the like, or a weak point is provided by, for example, thinning a middle part of the terminal rod, and a flange is formed at the end that is led out through the blocking plate. A structure in which the lead plate is fixed to the flange portion, or a terminal plate in which internal terminals are provided on an insulating plate of a rigid material is fixed on the capacitor element, and the external terminal and the internal terminal of the sealing lid are notched. When the gas pressure inside the capacitor rises due to energization and the sealing lid bends outward and deforms, In response to the tension of the sealing lid and the cutting action of the blocking plate, the terminal bar and the lead plate are peeled off, or the weak portion of the terminal bar breaks and interrupts the current, and the latter breaks the metal foil lead plate. Cut off current A shall (Japanese Utility Model 49-105852
JP, JP-A-49-110253, JP-A-47-11336, etc.).

In another embodiment, the capacitor case is formed as a double case including an outer case provided with an external terminal and an inner case having a bottom to prevent the appearance of the capacitor from being deformed when the internal pressure rises. In a metal inner case having a bottom surface, or a plug-shaped valve body that moves with gas pressure by closing a hole provided in the bottom surface, A space portion is formed by covering an inner case made of an insulating material with a bridge piece and a lead piece fixed in an inverted state, and when gas pressure is generated in the space portion, utilizing the deformation of the bottom surface of the inner case. The lead of the capacitor element welded to the inner surface of the inner case is broken by tension, or the valve element is moved by gas pressure to break the bridging lead, and the electric circuit between the capacitor element and the external terminal is broken. There is a proposal to cut off the (Japanese Utility Model 57-2
No. 6835).

In recent years, in order to prevent ignition or explosion that occurs when an overcharge or short circuit occurs in a sealed secondary battery, especially a lithium secondary battery, a safety device that operates and shuts off current when the battery pressure increases. However, JP-A-2-112151, JP-A-2-88063, (US Pat. No. 4,943,497)
And so on. This is the above-mentioned actual opening 49-105852
This is similar to the mechanism shown in Japanese Patent Application Laid-Open Publication No. H10-15064, in which a safety valve also serving as an inner lid is used instead of a sealing lid, and a lead blocking stripper corresponding to a blocking plate is used. FIG.
FIG. 18A is a side sectional view of the embodiment before the current interruption operation, and FIG. 18B is a state after the operation. FIG. 18A shows the structure. Reference numeral 82 denotes a metal safety valve also serving as an inner lid that is deformed outward due to an increase in battery internal pressure, and reference numeral 84 denotes a lead cut-off mounted in contact with the safety valve via an insulator 83. Stripper 86 is a cap-shaped external terminal plate provided with an exhaust hole 86a, and a lead plate 87 derived from the positive electrode plate.
Is welded to the tip of the projection 82a of the safety valve, which is inserted into the hole 85 of the stripping stripper. The positive electrode lead plate 87 is connected to the stripper 84.
And the projection 82a of the safety valve is bridged. When the gas pressure in the battery exceeds a predetermined value due to current supply such as overcharging, a tensile stress is generated in the welded portion together with the deformation of the safety valve. However, the positive electrode lead plate 87 is blocked by the stripper 84, and the stripper 84 shown in FIG. As shown in ()), the protrusion of the safety valve peels or breaks and comes off, so that the current is interrupted. Regarding this safety device, an assembling workability is improved by using a resin-made intermediate fitting body and mounting the safety valve and the stripper by concave and convex fitting (Japanese Patent Laid-Open No. 2-288063). Also, a plurality of ventilation holes are provided in the stripper, and a circular arc and a linear thin portion extending outward from the end of the arc are provided on the surface of the safety valve to improve safety (Japanese Utility Model Laid-Open No. 4-426262). Improvements have also been proposed.

[0013]

The use of a safety device provided with the above-described current interruption mechanism, which cannot be solved by a conventional safety device comprising a break valve or a PTC element and a break valve, requires continuous overcharging, It is possible to solve the problem of battery rupture and ignition caused by reverse charging or the like. However, when the above-described various current interrupting mechanisms are applied to a small, small-diameter sealed secondary battery requiring a high energy density, particularly a lithium secondary battery or the like, and an attempt is made to use the same in a small electronic device or the like. In addition, the external terminal plate or the like on the battery head is deformed, the space efficiency of the shutoff mechanism is poor, and the battery energy density is reduced. In addition, reliability tends to decrease, such as an increase in circuit resistance due to incomplete contact, instability, or disconnection due to a drop impact during use. Also,
There have been problems such as the production stability of the shut-off mechanism, in particular, the quality of the assembly tends to deteriorate during mass production of batteries.

The double can-sealing type disclosed in US Pat. Nos. 4,992,344 and 4,028,478, which are the first examples of the conventional current interrupting mechanism, has poor volumetric efficiency and lower energy density. In addition, when the size is reduced, the contact resistance and the operating state are likely to be unstable due to problems in processing accuracy and the like. In the following U.S. Pat.Nos. 5,026,615 and 3,617,386, a switch system using a warped elastic metal contact plate and a diaphragm, when applied to a small-diameter battery, the assembly process becomes complicated, and the assembly workability is reduced, and Resistance tends to be unstable. In addition, the volume occupancy of the sealing portion accommodating the blocking mechanism tends to increase. U.S. Pat.No. 3,939,011 discloses a method in which a lower end of a conductive tube connected to a cap terminal is brought into contact with a positive lead contact provided on a bottom surface of a battery container, and thus is affected by battery assembly accuracy. Contact failure or fluctuations in the cutoff operating pressure are likely to occur. Further, when an external impact is applied to the bottom surface of the battery container or the like, there is a problem that a shut-off operation or a failure occurs, or the bottom surface of the battery expands and becomes large when shutting off.

Since the conventional proposal described above is a contact conduction type, the contact resistance value is liable to fluctuate due to the influence of the accuracy at the time of assembly and the storage environment, and the charge / discharge characteristics during normal use are reduced. Therefore, it was unsuitable for batteries requiring high energy density. As a structure different from each of the above examples, a method of operating an external switch by movement of a pin-shaped lever on the battery side, described in U.S. Patent No. 3,622,397,
Although the battery configuration is simplified, it does not function except for a dedicated battery holder provided with a switch, and poses a practical problem since danger remains.

[0016] Shokai Shokai 49, a proposal for improvement of electrolytic capacitors
As described above, since the terminal rod or the metal foil lead plate is peeled or broken by the bending tension of the sealing lid due to the internal pressure as described above, the conduction failure does not occur due to the change in contact resistance. It has been difficult to employ a small high-energy-density battery because the lid is swollen and the outer shape becomes large, the dimension in the height direction becomes large, and the volume efficiency is reduced. Further, Japanese Utility Model Laid-Open No. 57-26835 discloses a double-container type with no deformation of the sealing lid, but the volume efficiency is greatly reduced, so that the practicality is poor.

As shown in the above-mentioned Japanese Patent Application Laid-Open No. 2-112151 and its improvement, as shown in FIG. 18, a positive electrode lead plate 87, which is broken or peeled off when the internal pressure of the battery rises, is parallel to the safety valve 82 and is flat. As a result, the safety device occupies a relatively small area as compared with the above-described modified example of the electrolytic capacitor, and the bending deformation of the external terminal plate during operation of the safety device (see FIG. 18B) is also eliminated. ing. As described above, in this safety device, the positive electrode lead plate 87 is welded to the projection 82a of the safety valve, and the current interruption operating pressure when the internal pressure of the battery rises is the same as the rupture and peel strength of the welded portion and the lid plate. It is determined by the correlation with the tensile stress of the safety valve, and the fluctuation of the welding strength is a large factor of the operating pressure. Therefore, the welding strength and the strength (thickness, material) of the lead plate are desirably set to a constant value, and cannot be too large to ensure safety. However, when the battery is sealed using the safety device as a sealing plate, the positive electrode lead plate is
It is bent and pushed into the open end of the battery container via the insulating gasket, and is fastened and fixed by bending the open end of the container. At this time, the bending stress generated in the lead plate was applied as tension and pressing force to the welded portion, thereby reducing the welding strength and fluctuating the operating pressure, and the welded portion was likely to come off.

When this safety device (sealing plate) is applied to a battery using an electrolyte mainly composed of a low flash point organic solvent, such as the above-mentioned lithium secondary battery, it is necessary to prevent accidental ignition of the electrolyte. As is usually the case with a non-aqueous battery of this type, it is necessary to first perform the welding connection between the projection of the safety valve and the lead plate, and then perform the sealing process through an electrolyte injection step. However, the tensile force and the pressing force applied to the welded portion for this purpose are due to the bending stress of the lead and the mechanical stress received from the battery holding and transporting device in the liquid injection process is added. As described above, even if the welding connection strength is set to a constant value, the fluctuation in the current interruption operating pressure tends to increase, and the occurrence rate of non-conducting batteries due to detachment of the weld in the assembled batteries tends to increase. Further, there is a case where the current is easily cut off by a drop, vibration, or the like during use of the battery. As a measure for improving the above-mentioned problem in the process of the safety device, as shown in FIGS. 19A and 19B, an aluminum valve drawn out from a central hole 94b of an aluminum lead cut-off stripper 94. Instead of the lead plate, a low-strength auxiliary terminal plate 95 made of aluminum foil (having a thickness of about 0.1 mm) having a diameter larger than that of the hole 94b is spot-welded to the tip of the projection 92a of the body.
6. A positive electrode lead plate 97 made of aluminum is placed on the upper surface of the auxiliary terminal plate as shown in the figure, and at the positions of points a and b on the auxiliary terminal plate surface on the outer peripheral side of the diameter of the hole, There is a method in which a lead plate, an auxiliary terminal plate, and a stripper are welded and connected by a laser, a spot welding machine, or the like.

In the figure, 93 is an intermediate fitting made of a soft resin for supporting the stripper, and 94a is a gas vent hole provided in the stripper. In this manner, in the battery assembling step, if each welding state is appropriate, mechanical stress such as lead plate bending stress can be prevented from directly exerting on the spot welding portion 96 of the valve body projection. However, at the time of mass production of the battery, the material, surface condition, and welding machine conditions of each part fluctuate, and it is difficult to reliably and integrally weld the three parts at points a and b. That is, when the welding conditions are weak, the welding between the auxiliary terminal plate and the stripper becomes incomplete, the auxiliary terminal plate is separated from this portion during battery assembly, and the auxiliary terminal plate is lifted up. Suffering from direct stress. If the welding conditions are too strong, holes will be formed in the positive electrode lead plate, and the welding strength will be reduced, and the lead plate will easily come off. Thus, a,
The three-part integrated welding at point b was insufficient in improvement effect, for example, welding unevenness was likely to occur during mass production, and conduction failure occurred during battery assembly or during use of the battery.

As described above, as an explosion-proof safety function including overcharging and reverse charging of a high-energy-density sealed battery such as a lithium secondary battery and explosion-proof safety, the internal pressure of the battery is increased by a sealing body. It is effective to provide a current interrupt mechanism that operates by
There have been problems such as deformation of the battery outer shape and reduction of volumetric efficiency (reduction of energy density).

In addition, there are many problems such as a change in voltage due to poor contact during use of the battery, or a decrease in the strength of the welded joint at the time of battery assembly. was there.

The present invention solves such a problem, and incorporates an explosion-proof mechanism such as a current cut-off mechanism, which operates when an internal pressure of a battery is abnormally increased due to overcharge or the like, into a sealing plate, and functions as a single sealing plate. This eliminates the effects of mechanical stress during battery assembly, facilitates mass production, and is suitable for sealed batteries such as lithium secondary batteries. Excellent operational stability of the mechanism,
An object of the present invention is to provide an explosion-proof sealing plate for a sealed battery.

[0023]

In order to solve these problems, an explosion-proof sealing plate according to the present invention is provided with a metal explosion-proof valve body (internal pressure of a battery) which is countered via an insulating ring or an insulating inner gasket. A thin valve body which is deformed outwardly as it rises, and an inner terminal plate / or a protruding terminal cover plate / or a protruding dish-shaped cover plate are provided near the center of each surface by ultrasonic welding or the like. An explosion-proof function, such as a current interrupting mechanism formed electrically by a welded portion, is incorporated in the sealing plate.

The sealing plate includes: (1) an external terminal plate 5, an explosion-proof valve body 1, an inner terminal plate 3 having a vent hole, and an intervening member interposed between the explosion-proof valve body and the peripheral edge of the inner terminal plate. The insulating ring 2 and the lead mounting cover plate 4 having a ventilation hole are stacked and accommodated in an insulating gasket 6, and the explosion-proof valve body and the projection 3a provided near the center of the inner terminal plate are combined. Are electrically connected by the welding portion S to form a current interrupting mechanism.

(2) The external terminal plate 5 and the explosion-proof valve body 1 are
An inner gasket 12 having a substantially L-shaped cross section and stacked in the insulating inner gasket 12 and having an inner terminal plate 3 having a ventilation hole on the bottom outer peripheral surface side of the inner gasket is raised to the ventilation hole and the periphery. The explosion-proof valve body and the inner terminal plate are housed in the dish-shaped lid plate 14 having the portion 14b, and the rising portion of the dish-shaped lid plate is bent inward to be integrally fastened. Are electrically connected by the welding portion S to form a current interrupting mechanism.

(3) An external terminal plate 5, an explosion-proof valve body 1, and a protruding terminal cover plate 3 having a vent and having a protruding portion 34a.
4, the explosion-proof valve body and the insulating ring 32 interposed between the peripheral edges of the protruding terminal cover plate are stacked and accommodated in the insulating gasket 6. The projections are electrically connected to each other by the welds S to form a current interrupting mechanism.

(4) The outer terminal plate 5 and the explosion-proof valve element 1 are connected to each other by an inner gasket
The stacking in the inside, the vent and the rising portion 44c
And housed in a protruding dish-shaped lid plate 44 having a protruding portion 44a formed in the vicinity of the center of the bottom surface. The rising portion of the protruded dish-shaped lid plate is bent inward to be integrally fastened. The explosion-proof valve body and the protruding portion of the protruding dish-shaped lid plate are electrically connected by a welding portion S to form a current interrupting mechanism.

(5) In the sealing plate configuration of the above items (1) to (4), a thick plate is provided between the explosion-proof valve body and the inner terminal plate / or the protruding terminal cover plate / or the protruding dish-shaped cover plate. A current interrupting mechanism is formed by being electrically connected by a welded portion S, which is welded with metal foils 52, 62, etc., having smaller strength and mechanical strength than the explosion-proof valve body.

(6) In the mode of the above item (5), the explosion-proof valve body 1 and the inner terminal plate 3/3 having a small hole 3c near the center are provided.
Or the protruding terminal cover plate 34 / or the protruding dish-shaped cover plate 4
4, a metal foil 52 larger than the diameter of the small hole is interposed, and the metal foil and the inner terminal plate and the like are fixed Sa by welding or bonding on the outer peripheral side of the small hole, and the metal The foil and the explosion-proof valve body are directly welded through the small holes to form a welded portion S and are electrically connected.

(7) In the sealing plate embodiment of the above items (1) to (4), when forming the current interrupting mechanism, ultrasonic welding is applied as a means for forming the welded portion S, and the welding strength is determined by the explosion proof. Make it smaller than the breaking strength of the valve body.

When an aluminum material is used as the component to be welded, preferably, an aluminum alloy to which magnesium and / or manganese is added is used as one or both of the material of the members, or the mechanical strength is higher than that of the aluminum material. However, a composite metal material having a large and corrosion-resistant metal as a base material and a thin layer of an aluminum material provided on the surface is used.

An inner terminal plate, a protruding terminal cover plate, or a protruding dish-shaped cover plate having a deformation strength near the center portion larger than a deformation strength of the pressure receiving surface portion of the explosion-proof valve body is used.

The height of each protruding portion provided on the inner terminal plate or the protruding terminal cover plate or the protruding dish-shaped cover plate is made lower than the bottom thickness of the insulating ring or the inner gasket, and the explosion-proof valve body is used when welding. Is bent to the side of each projection and welded.

(8) A conductive sealant is interposed between the inner terminal plate described in the above items (1) and (2) and the contact surface of the lead mounting lid plate or the dish-shaped lid plate by coating or the like. .

(9) A thin portion is provided on a part of the pressure receiving surface excluding the welded portion of the explosion-proof valve body or the thin metal plate valve body by press working, cutting, or the like.

(10) Between the external terminal plate and the explosion-proof valve body,
A ring-shaped PTC element is arranged.

[0037]

By using the explosion-proof sealing plate having such a configuration, when the battery is in an abnormal use state such as overcharge, reverse charge, external short circuit or the like, and the internal pressure of the battery rises and reaches a predetermined pressure, the explosion-proof valve is closed. The explosion-proof valve body is peeled from the welded part with the inner terminal plate or the protruding terminal cover plate or the protruding dish-shaped cover plate due to the stress that the body is deformed outward (external terminal side), or the metal foil body is broken The electrical connection is cut off. This current interruption operation can prevent a sudden rise in temperature, rupture, or explosion of the battery due to energization without deforming the appearance of the battery or lowering the volumetric efficiency.

Further, by providing a current blocking function inside the explosion-proof sealing plate, the connection between the lead plate derived from the electrode and the explosion-proof sealing plate can be strengthened by welding or the like. Problems such as defective assembly during assembling can be solved.

Further, when forming the welded portion, a specific metal material is used as a constituent material of the explosion-proof valve body and the like, and ultrasonic welding or the like prevents troubles such as poor connection during use of the battery. When the battery internal pressure reaches a predetermined value, the explosion-proof valve body is peeled off, and the current interruption operation can be reliably performed.

As described above, by using the explosion-proof sealing plate of the present invention, a sealed battery with high safety and reliability can be produced.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A specific embodiment of the present invention will be described below with reference to the drawings.

Example 1 FIGS. 1, 2 and 3 are views showing an explosion-proof sealing plate for a sealed battery according to a first embodiment of the present invention. The explosion-proof sealing plate 9 has a flexible thin metal explosion-proof valve body 1, an insulating ring 2, an inner terminal plate 3 having a vent 3b in the center provided with a projection 3a, and a metal through-hole. It is composed of a lead mounting lid plate 4 having pores 4a, a metal external terminal plate 5, and an insulating gasket 6. The explosion-proof valve body 1 is located above the inner terminal plate 3 via the insulating ring 2, and is welded to the upper surface of the projection 3a of the inner terminal plate 3 near the center thereof by ultrasonic welding, resistance welding, laser welding, or the like. Thus, a welded portion S is formed and electrically connected.

Next, the operation of the explosion-proof sealing plate of the first embodiment for interrupting the current in response to an increase in the internal pressure of the battery will be described with reference to FIG.
Description will be made with reference to (A) and (B).

The explosion-proof sealing plate is welded to the surface of the lead mounting cover plate 4 on the lower surface side with a lead plate 7 derived from one of the electrode plates 10 and is connected to the electrode group by an electrolytic solution. Is inserted inside the opening of the battery case 8, the upper end of the battery case 8 is caulked and fastened as shown to seal the battery.

When this battery generates gas, steam, etc. due to improper energization such as overcharge, short circuit or reverse charge, and the internal pressure of the battery rises, the internal pressure of the battery is increased by the lead mounting cover plate and the internal terminal plate. Is applied to the inside of the explosion-proof valve body 1 through the ventilation holes 4a and 3b provided in the airbag. The explosion-proof valve body 1 is fixed by caulking its outer peripheral portion by a battery case 8 via an insulating gasket 6, and when the battery internal pressure reaches a predetermined value, as shown in FIG. The central portion bulges upward, the welded portion S is peeled off by the deformation stress at that time, the connection with the inner terminal plate 3 is released, and the current is cut off.

(Embodiment 2) FIGS. 4, 5 and 6 show a second embodiment of the present invention. The same external terminal plate 5 and explosion-proof valve body 1 as described above are stacked and mounted in an insulating inner gasket 12 made of a resin such as polypropylene in a substantially L-shaped annular shape, and the bottom portion of the inner gasket. An inner terminal plate 3 having a vent 3b is provided on the outer peripheral surface, and the inner terminal plate 3 (FIG. 4) is provided near the center of the explosion-proof valve body 1.
In (A), the projection 3a is welded to the upper surface by ultrasonic welding or the like to form a welded portion S, and the two are electrically connected.

After these are placed and accommodated in a metal dish-shaped cover plate 14 having a vent hole 14a and a rising portion 14b on the periphery, the rising portion 14b of the dish-shaped cover plate is bent inward and crimped. The explosion-proof sealing plate 11 is formed by forming the portion 14c and fastening it together. An example of a method of connecting the above explosion-proof valve body and the inner terminal plate by ultrasonic welding is shown in FIG.

The bottom surface of the inner terminal plate 3 is fixed to a fixing stand (anvil) A.
v, and the explosion-proof valve body 1 housed in the inner gasket 12 is mounted thereon and connected to the ultrasonic vibrator.
The weight of the tip of the explosion-proof Hq is adjusted, pressed against the vicinity of the center of the explosion-proof valve body, and ultrasonic vibration (for example, 40 KHz) is applied, thereby welding the surfaces of the explosion-proof valve body and the inner terminal plate by frictional heat. Then, a welded portion S is formed.

Next, an example in which the explosion-proof sealing plate 11 of this configuration is applied to a cylindrical lithium secondary battery will be described with reference to FIG. As for the constituent materials of the explosion-proof sealing plate, when connected to the negative electrode plate, the same as when connecting to the positive and negative electrodes of an alkaline storage battery, nickel, a steel plate with a nickel layer on the surface, stainless steel, etc. Applicable without care. However, when connected to the positive electrode plate, a high potential is applied and there is a high possibility of corrosion by the electrolytic solution. Therefore, it is necessary to use aluminum, titanium, ferrite-based specific stainless steel with good corrosion resistance, etc. In order to avoid an increase in resistance, at least the explosion-proof valve body and the inner terminal plate (or including a protruding terminal cover plate described later) are preferably made of a metal material mainly made of aluminum or aluminum alloy which is advantageous in terms of conductivity. Is used. The dish-shaped lid plate is similar to the material of the positive electrode lead plate or has good weldability. For example, in the case of an aluminum-based lead plate, an aluminum-based or metal plate having an aluminum layer on the surface is suitable. As the external terminal plate, a steel plate or a stainless steel surface-treated with nickel or the like is used.

The battery is composed of a positive electrode plate 17 made of a lithium composite oxide powder (such as lithium cobalt oxide), a graphite powder, a binder, etc., and applied to an aluminum foil substrate.
a, paste such as graphite powder, binder, etc.
An electrode plate group 17 in which a negative electrode plate 17c coated on a substrate such as a copper foil (or a lithium foil adhered to the substrate) is wound via a separator 17b such as a microporous polyethylene film.
Together with the lower insulating plate 16 in a metal battery case 15 also serving as a negative electrode terminal, and the tip of a positive electrode lead plate (aluminum) 18 led out through the upper insulating plate 19 is
The surface of the dish-shaped lid plate (made of aluminum) 14 of the explosion-proof sealing plate 11 inserted in the insulating gasket 6 is fixed by welding by spot welding or laser welding.

Next, the inorganic solute was made of ethylene carbonate,
After injecting a predetermined amount of a non-aqueous electrolyte dissolved in propylene carbonate or another single or composite organic solvent, the positive electrode lead plate was bent, and the explosion-proof sealing plate 11 was provided near the opening end of the battery case. 15a, and then crimp the open end of the battery case inward and tighten (1).
5b) to obtain a sealed battery.

Embodiment 3 Embodiments 1 and 2 above
5A, aluminum powder or silver powder is dispersed in a resin solution such as acrylic resin between the inner terminal plate 3 and the dish-shaped lid plate 14 or the lead mounting lid plate, as shown by 14e in FIG. The explosion-proof sealing plate is formed by coating and applying the conductive sealing agent thus obtained. As a result, even if a material having a large surface contact resistance such as stainless steel is used as the metal component material, the contact surface resistance value can be reduced, and the voltage drop loss during high-rate discharge can be reduced. Further, there is an effect that the sealing property of the metal-to-metal contact portion between the inner terminal plate and the lead attachment cover plate in the first embodiment is improved, and the liquid leakage resistance of the battery is further improved.

(Embodiment 4) FIG. 7 shows Embodiment 3 of the present invention.
3 is a diagram showing a side cross section of the explosion-proof sealing plate 31 of FIG. This embodiment is different from the first embodiment in that the inner terminal plate 3 and the lead mounting cover plate are replaced with a vent hole 34b and a protruding portion 34a as shown in the drawing.
Is used. An insulating ring interposed between the protruding terminal cover plate 34 and the explosion-proof valve body 1 is provided on the upper and lower surfaces indicated by 32 with a polyolefin-based heat-sensitive adhesive (hot melt adhesive). After the three members are integrated by thermocompression bonding or the like, a welded portion S is formed. Thereby, the airtightness between the protruding terminal cover plate 34 and the peripheral edge of the explosion-proof valve body 1 can be completely equalized, and the airtight liquid-tightness as a sealing plate can be further improved.
This embodiment is suitable for a battery having a relatively small diameter.

(Embodiment 5) FIG. 8 shows an embodiment 4 of the present invention.
3 is a diagram showing a side cross section of the explosion-proof sealing plate 41 of FIG. This is to replace the inner terminal plate 3 and the dish-shaped lid plate 14 shown in Embodiment 2 by integrating them, and to replace the two members with the ventilation holes 4.
4b and a protruding dish-shaped lid plate 44 having a rising portion 44c on the periphery and a protruding portion 44a formed near the center of the bottom surface as shown in the figure. When the explosion-proof sealing plate of this embodiment is applied, for example, in a small battery having a diameter of 15 mm or less,
Although no special consideration is required for the material of the protruding dish-shaped lid plate, when the outer diameter is large, a material having a higher rigidity or a metal material having an increased thickness compared to the dish-shaped lid plate of Example 2 is used. It is preferred to apply.

This is to prevent a change in the current cutoff pressure due to, for example, bending at the center portion during swaging.

In the constructions of Examples 1 to 5 described above, the explosion-proof valve body 1, the inner terminal plate 3, the protruding terminal cover plate 34,
Alternatively, as described in the second embodiment, various metal materials can be used as the metal material for forming the welded portion S such as a protruding dish-shaped lid plate. Which is connected, battery voltage, current cutoff set pressure,
The material and thickness are determined in consideration of the welding method and the like. In a sealed alkaline battery system, a metal material having a stable welding property such as a steel plate having a thin nickel layer on its surface, a nickel thin plate, and a nickel-based alloy thin plate can be used.

As described in the second embodiment, the sealed non-aqueous secondary battery such as a lithium-based non-aqueous battery in which the present invention exhibits a remarkable effect is used for reasons such as corrosion resistance, reduction of electric resistance, and stability of welding. Aluminum-based metal materials are easy to use, and a combination of specific aluminum alloy materials is preferable as described later.

In each of the embodiments described above, the explosion-proof valve body and the inner terminal plate or the protruding terminal cover plate or the protruding dish-shaped cover plate are connected when the internal pressure of the battery rises to a predetermined value or more. This is a method in which the connection by the welded portion S is released. Therefore, it is necessary to surely peel off the welded portion before the damage prevention including the minute hole occurs in the explosion-proof valve body 1. Therefore, welding conditions are set so that the welding strength of the welding portion S is smaller than the breakage strength of the explosion-proof valve body 1. When the aluminum material described in the second embodiment is used, ultrasonic welding, pressure welding by pressurization, etc. can be applied. Is preferably formed by ultrasonic welding.

Further, in order to ensure that the current is interrupted, the inner terminal plate 3 or the protruding portion having a larger deformation strength around the central portion than the deformation strength of the pressure receiving surface portion receiving the internal pressure of the explosion-proof valve body 1 is required. Protruding terminal cover plate 3 with high peripheral deformation strength
4. A protruding dish-shaped lid plate 44 may be used. Accordingly, when the internal pressure of the battery increases, the internal terminal plate and the like can withstand the deformation stress and maintain the original shape, so that the current interruption pressure can be stabilized. Specifically, the strength of the inner terminal plate and the like is set to approximately 1.5 times or more the explosion-proof valve body as a guide.
In the case of the inner terminal plate, a material having a large thickness and strength is preferable, and in the case of a protruding terminal cover plate, the deformation strength of the peripheral edge thereof, including the influence of the molding shape of the projection, is less than the strength of the explosion-proof valve body. A material that is 1.5 to 2 times or more is used.

Further, in the constitutions of the above-mentioned Examples 1 to 5, as in the case of the above-mentioned sealed type lithium secondary battery or the like, the explosion-proof valve body 1 and the inner terminal plate 3 or the protruding terminal cover plate 3 are provided.
When an aluminum-based material is used as the material of the projection-shaped cover plate 4 or the projection-shaped cover plate 44, if the ultrasonic welding method is employed as shown in FIG. Peeling can be reliably performed, and the current interruption operation can be stably performed.

If the aluminum material to be used is selected according to the set values of the current cutoff pressure and the breaking pressure at the time of abnormal overpressure of the explosion-proof valve body, the assembly construction of the explosion-proof sealing plate is further facilitated.
When the breaking pressure of the explosion-proof valve is set to 20-30 kgf / cm ² or more and the current cutoff pressure is set to a high operating pressure such as 15 kgf / cm ² or more, pure aluminum (JIS 1000 series) generally used as foil and thin plate material A1050, AIN
30 or the like is applicable. However, the current cutoff pressure varies depending on the battery system to be applied and its constituent conditions, and is 10 to 1
5 kgf / cm ² still may require a 5 kgf / cm ² before and after the low-pressure setting. In this case, the adjustment is difficult with pure aluminum material, and the shutoff pressure fluctuation tends to increase. The correspondence is shown below.

(Embodiment 6) The explosion-proof valve body used in the above Embodiments 1 to 5 and the inner terminal plate or the protruding terminal cover plate or the protruding dish-shaped cover plate are formed on at least one side to be welded. Aluminum alloy to which magnesium or manganese or both are added, such as Al-Mg alloy (A5005, A50
52 etc.) or A3003, A320 of Al-Mn type
3. A3004, A3105, A containing Al and Mn
An alloy thin plate or foil such as 5454 is used. However, the amount of added magnesium is preferably selected from the range of about 0.5 to 3% (for an excessively added product, the welded portion may become brittle with time). The alloy to which magnesium or manganese has been added can adjust the welding strength in a wide range by ultrasonic welding, so that even if the current interrupting pressure is reduced, the alloy can be stably peeled under pressure. When it is set to about 3 to 5 kgf / cm ² , the above alloy material is preferably used for both constituent materials.

Instead of the aluminum alloy, a composite metal material is used in which a thin layer of an aluminum material is provided on the surface of a corrosion-resistant base material such as a stainless steel plate by the Crat method or the like.

When the above is applied to the inner terminal plate, the protruding terminal cover plate, etc., the strength against deformation can be increased.

(Embodiment 7) FIGS. 9 and 11 show the fifth embodiment of the present invention and the structure of the sealing plate of the first to fifth embodiments.
Between the explosion-proof valve body 1 and the inner terminal plate 3 or the protruding terminal cover plate 34 or the protruding dish-shaped cover plate 44, the thickness and the mechanical strength (rigidity, hardness) are smaller than those of the explosion-proof valve body. Metal foil 5
The welded portion S is formed with 2, 62, 63 and 64 interposed. Taking an example in which an aluminum-based material is used as each component, the thickness of the metal foil body is about 0.1 to 0.5 times the thickness of the explosion-proof valve body, and the mechanical strength (tensile strength) Etc.) are used. As an example, the explosion-proof valve body is A3003 or A1N3 with a thickness of 0.15 mm.
0, and A having a thickness of 0.05 mm as foil bodies 52, 62, etc.
A semi-rigid or annealed material such as 1050 or A1N30 is used. The inner terminal plate 3 has a thickness of 0.25 to 0.5 mm.
A3003, A5005, A5052, etc. were used. In the example of FIG. 9, as shown in FIG. 9A, an aluminum foil 52 is spot-welded to the center of the inner terminal plate 3 and the explosion-proof valve body 1 fitted in the inner gasket 12 shown in FIG. The welding portion S is formed by ultrasonic welding. FIG.
The example 1 is a metal foil body shown in (A) 62 provided with an arc-shaped notch 62a in (B) 62, a metal foil body provided with a large notch 63a and a notch 63b in (C) 63,
The notch 64b as small as (D) and the arc-shaped thin portion 6
Using a member 64 provided with 4a or the like, it is fixed to the back surface of the explosion-proof valve body 1 with a conductive adhesive or brazing or the like, assembled, and welded to form a welded portion S.

(Embodiment 8) FIG. 10 shows an embodiment of the sixth aspect of the present invention, in which the configuration of the seventh embodiment can be applied to a lower current interruption pressure. As shown in (A), the vent 3b and the small hole 3c (1.
(About 5 to 5 mm) around the small hole peripheral portion 3d of the inner terminal plate 3
Then, as in the seventh embodiment, an aluminum foil of about 0.05 mm is used as the metal foil 52, and is fixed by spot welding, laser welding, ultrasonic welding, or a conductive adhesive.
After that, the explosion-proof valve body 1 and the foil body 52 are welded by ultrasonic welding or the like through the small diameter 3c of the inner terminal plate as shown in FIG.
Are formed and connected. In addition to the inner terminal board,
In the case of using the protruded terminal cover plate 34 and the protruded dish-shaped cover plate, the same can be achieved by providing appropriate small holes. In this embodiment, the current interruption operation is performed by peeling or breaking the metal foil body, so that the thickness of the metal foil body and the mechanical strength can be selected to stabilize even at a low pressure of ^{3 to 5} kgf / cm ^2. Current interruption.

If the explosion-proof sealing plate of each embodiment described above is properly used depending on the shape and size of the battery, a more stable effect can be obtained. That is, the one using the cover plate having no rising portion on the periphery such as the first and fourth embodiments is used for a battery having a relatively small diameter and a small size, and the dish-shaped cover having the rising portion on the periphery such as the second and fifth embodiments. The method of caulking and assembling using a plate is suitable for a large-diameter or elliptical battery because each member is fixed in the sealing plate and the overall strength can be maintained.

In the above embodiments, if the explosion-proof valve body 1 is made of a thin and soft material, the internal pressure fluctuates when the battery internal pressure rises and the welded portion peels off. As shown in the cross-sectional view of FIG. 12, the height d of the projection 3a of the inner terminal plate 3 is set to the thickness of the insulating ring 2 in order to prevent incomplete connection with the inner terminal plate. D
2, the explosion-proof valve body 1 is bent toward the protruding portion during welding to form a welded portion S. The same configuration is used in other examples using the protruded terminal cover plate 34, the protruded dish-shaped cover plate 44, and the inner gasket 12.

In the second embodiment, the inner terminal plate 3
When the thickness of the inner gasket is thin, a configuration may be used in which the projection is not provided as shown in FIG. 13 and a slightly upward warpage is provided. If the explosion-proof valve body is bent and welded as shown in the drawing,
The same effect as described above can be obtained.

The explosion-proof valve body 1 used in the present invention has a function of preventing a battery explosion due to internal pressure being partially broken when the battery is thrown into a fire or abnormally heated, in addition to the current interruption function. However, the formation of the welded portion S tends to increase the breaking operation pressure.
Therefore, when the battery sealing strength is low, 1 in FIGS.
a, or 1b in FIGS. 4 and 5, it is preferable to provide an arc-shaped thin portion by machining or the like to lower the breaking pressure of the explosion-proof valve body. The operation state is indicated by 1x in FIG.

Further, FIG. 14, FIG. 7, FIG.
If a ring-shaped PTC element such as “Polyswitch” (trade name) manufactured by Raychem Co. is inserted between the external terminal plate 5 and the explosion-proof valve body 1 at 72 in FIG. Can operate immediately when an external short circuit or excessive current is applied, and the safety of the battery can be ensured before the current cut-off function is activated, so that the battery can be used economically.

Next, the sealed lithium secondary battery (AA type, 3.7 V, 550 mAh) shown in Example 2 of the present invention was manufactured in the same manner as in Example 2 of the present invention (FIG. 4). A battery according to the present invention sealed using an explosion-proof sealing plate 11 made of a metal material (aluminum alloy) and a conventional battery sealed using an explosion-proof sealing plate (laminate sheet valve) shown in FIG. In a room at about 25 ° C., continuous charging (5 each) was performed with a current of 1 A (ampere).
5 and FIG. As can be seen from both figures, this battery begins to generate heat and the battery internal pressure suddenly increases when the amount of charged electricity exceeds 100% of the nominal capacity, and when it exceeds 200%, the battery internal pressure becomes 15 to 20 kgf / cm ^2. Reach At this time, the thin valve body 42a of the conventional explosion-proof sealing plate is broken (vented), and the generated gas is exhausted. However, the charging was continued, and when the battery temperature reached 100 to 120 ° C., a sudden abnormal reaction occurred, and the battery exploded (marked by X in FIG. 17).
However, in the battery equipped with the explosion-proof sealing plate of the present invention, as shown in the drawing, when the battery internal pressure is 15 kgf / cm ² , the current cutoff function is activated, the current is cut off, and both the temperature rise and the gas generation are stopped. The safety of the battery is ensured.

When the explosion-proof sealing plate was assembled and the state of occurrence of defects during battery production was examined, it was found that the explosion-proof sealing plate of the present invention was employed, the one shown in FIG. 19, the current interruption operating pressure and the reference value were set to about 12 kgf / cm ² , and 2000 pieces of each were assembled, assembled into a battery, and a drop test was performed from a height of 1 m. Then, disconnection occurred in four cells, but none of the cells of the present invention was disconnected. Further, an overcharge test was performed while measuring the battery internal pressure for each of the 20 cells after the test. As a result, 9.5 to 14 kgf / cm ² , 7 to
At 19 kgf / cm ² , it was 8 to 17 kgf / cm ² .

In the above-described lithium secondary battery system, the set value of the current cut-off operating pressure differs depending on the prescription and the structural conditions of the battery, and high accuracy is often required. Examples of the present invention, in addition to those described above, those of Example 8,
And the above-mentioned conventional example,
Assuming that the reference value is 6.5 kgf / cm ² , 1000 pieces are assembled,
The battery was assembled, 30 cells were withdrawn, and the current interruption operating pressure was examined by overcharging.

As a result, in the case of the present invention, 4.7 was obtained.
９9.5 Kgf / cm ² , 5.8-7.5 K in the case of Example 8
a gf / cm ^2, the conventional example of what, 1.5~13Kgf / cm
^{As the} width increased to ² , the number of disconnections exceeded 10%. In the case of the conventional example, it is more stable but insufficient.

Further, in the explosion-proof sealing plate of the present invention, the explosion-proof valve body is provided with a thin portion to adjust the breaking pressure,
By incorporating the element in the sealing plate, safety against abnormal heating such as when it is thrown into a fire other than energization, and safe and reusable battery when excessive current flows due to short circuit etc. be able to. In addition, since the explosion-proof sealing plate of the present invention incorporates all of the explosion-proof safety functions such as a current cutoff function and a rupture valve and a PTC element in the sealing plate, the road condition and the lower limit operating pressure are measured before the battery is assembled. Therefore, it is possible to provide a more accurate explosion-proof sealing plate.

[0077]

By using the sealed explosion-proof sealing plate of the present invention, it is possible to reliably and effectively prevent abnormal heat generation and ignition rupture of the battery when the battery is abnormally energized such as overcharging, reverse charging and short circuit. It is possible to obtain a highly reliable sealed battery in which the quality at the time of production is stable, the malfunction does not easily occur even when an impact such as a vibration drop is applied, and the like.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an explosion-proof sealing plate for a sealed battery according to a first embodiment of the present invention.

FIG. 2A is an exploded perspective view of the sealing plate according to the first embodiment of the present invention, and FIG.

FIG. 3A is an explanatory diagram of an operation state of a battery using the explosion-proof sealing plate of the first embodiment. FIG. 3B is an explanatory diagram after the operation.

FIG. 4A is a cross-sectional view of a configuration of an explosion-proof sealing plate according to a second embodiment of the present invention. FIG.

FIG. 5A is a perspective view showing a configuration of an explosion-proof sealing plate according to a second embodiment. FIG.

FIG. 6 is a sectional view of a lithium secondary battery sealed with an explosion-proof sealing plate of Example 2.

FIG. 7 is a sectional view of an explosion-proof sealing plate according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of an explosion-proof sealing plate according to a fifth embodiment of the present invention.

FIG. 9 (A) is a view showing a configuration of an explosion-proof sealing plate according to another configuration method of Examples 1 to 5 of the present invention.

10A is an assembly view showing an explosion-proof sealing plate according to another configuration of the seventh embodiment of the present invention. FIG.

11A is a cross-sectional view of a sealing plate according to another embodiment of the first to fifth embodiments of the present invention. FIG. 11B is an assembly view of an explosion-proof valve body. FIG. 11C is a view showing a metal foil body. Figure showing

FIG. 12 is a diagram showing the configuration conditions in the explosion-proof sealing plates of Examples 1 to 5 of the present invention.

FIG. 13 is a cross-sectional view showing another example of an explosion-proof sealing plate according to the second embodiment of the present invention.

FIG. 14 is a cross-sectional view of a PTC element incorporated in an explosion-proof sealing plate according to a second embodiment of the present invention.

FIG. 15 is a characteristic diagram when a sealed battery using the explosion-proof sealing plate of the present invention is continuously overcharged.

FIG. 16 is a sectional view showing an example of a conventional explosion-proof sealing plate.

FIG. 17 is a characteristic diagram when a sealed battery using a conventional sealing plate is continuously overcharged.

18A is a cross-sectional view of a conventional battery using an explosion-proof sealing plate having a current interrupting function. FIG. 18B is a cross-sectional view of a main part showing the same operation state.

FIG. 19 (A) is a cross-sectional view showing an improvement plan of a conventional explosion-proof sealing plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Explosion-proof valve 2 Insulation ring 3 Inner terminal plate 4 Lead mounting cover plate 5 External terminal plate 6 Insulating gasket 7 Lead plate 8 Battery case 9 Explosion-proof sealing plate 11 Explosion-proof sealing plate 12 Inner gasket 14 Plate shape Lid plate 15 Battery case 17 Electrode group 18 Lead plate 21 Explosion-proof sealing plate 23 Inner terminal plate 31 Explosion-proof sealing plate 32 Insulating ring 34 Protruding terminal cover plate 35 Sealant 41 Explosion-proof sealing plate 44 Lid plate 52 Metal foil body 61 Explosion-proof sealing plate 62 Metal foil body 63 Metal foil body 64 Metal foil body 71 Explosion-proof sealing plate 72 PCT element 1a Thin part 1b Thin part 3a Projection part 3b Vent hole 3c Small hole 4a Vent hole 5a Exhaust hole 14a ventilation hole 23b ventilation hole 34a projection 34b ventilation hole 44a projection 44b ventilation hole 63b cut 64a thin portion d center projection height d2 insulating ring thickness Sa Wearing portion S welded portion

──────────────────────────────────────────────────の Continued on the front page (72) Inventor Yukimasa Niwa 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Yasushi Hirakawa 1006 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (58) Field surveyed (Int.Cl. ⁶ , DB name) H01M 2 / 12,2 / 04 H01M 2 / 06,2 / 34

Claims (15)

(57) [Claims] An electrode plate group comprising a positive electrode plate, a negative electrode plate, and a separator, and a sealing plate for sealing a battery case containing an electrolyte. The sealing plate is made of a metal external terminal plate 5 and a battery internal pressure. Metal explosion-proof valve body 1 that deforms outward as it rises
And an inner terminal plate 3 made of metal and having a ventilation hole 3a, and an insulating ring 2 interposed between the explosion-proof valve body and the peripheral edge of the inner terminal plate.
And a lead mounting cover plate 4 made of metal and having a ventilation hole 4a.
The inner terminal plate 3 is electrically connected to the explosion-proof valve body by a welded portion S between the protrusion 3a provided near the center of the inner terminal plate 3 and the explosion-proof valve body 1. Connected, when the battery internal pressure exceeds a predetermined value, the explosion-proof valve body is peeled off by the stress deformed outward, so that the electrical connection between the inner terminal plate and the explosion-proof valve body is cut off. An explosion-proof sealing plate for sealed batteries. 2. A terminal member such as a metal external terminal plate 5;
An explosion-proof valve body 1 made of metal, which is deformed outward with an increase in battery internal pressure, is connected to an insulating inner gasket 1 having a substantially L-shaped cross section.
2, inner terminal plates 3, 23 made of metal and having ventilation holes are arranged on the bottom outer peripheral surface side of the inner gasket,
This is accommodated in a metal dish-shaped lid plate 14 having a vent hole 14a and a rising portion 14b on the periphery, and the rising portion of the dish-shaped lid plate is bent inward to be integrally fastened to the battery. The inner terminal plate has a welded portion S with an explosion-proof valve body near its center.
Is electrically connected to the explosion-proof valve body, but when the internal pressure of the battery exceeds a predetermined value, the welded portion is peeled off by the deformation stress of the explosion-proof valve body, and the electric connection between the inner terminal plate and the explosion-proof valve body. An explosion-proof sealing plate for a sealed battery, wherein the explosion-proof sealing plate is configured so as to cut off the electrical connection. 3. The conductive sealant according to claim 1, wherein a conductive sealant is interposed between the contact surfaces of the metal inner terminal plates 3 and 23 and the lead mounting cover plate 4 or the dish-shaped cover plate 14. Sealing plate for sealed batteries. 4. A terminal member such as a metal external terminal plate 5;
A metal explosion-proof valve body 1 that deforms outward with an increase in battery internal pressure, a metal protruding terminal cover plate 34 having a vent hole 34b and a protruding portion 34a formed near the center, and the explosion-proof valve Insulating ring 3 interposed between the body and the peripheral edge of the protruding terminal cover plate
2 and are housed in the insulating gasket 6. The protruding terminal cover plate 34 is electrically connected to the explosion-proof valve body by a welded portion S between the protrusion 34 a and the explosion-proof valve body 1. When the battery internal pressure exceeds a predetermined value, the welded portion is peeled off by the deformation stress of the explosion-proof valve body, and the electrical connection between the protruding terminal cover plate and the explosion-proof valve body is cut off. Characteristic explosion-proof sealing plate for sealed batteries. 5. A terminal member such as a metal external terminal plate 5;
The metal explosion-proof valve body 1 that is deformed outward with an increase in battery internal pressure is stacked in an insulating inner gasket 12,
This is accommodated in a metallic protruding dish-shaped lid plate 44 having a vent hole 44b and a raised portion 44c on the periphery and having a protruding portion 44a formed near the center of the bottom surface. 44c is a battery sealing plate that is bent inward and fastened together, wherein the protruding dish-shaped lid plate 44 is formed by a welded portion S between the protruding portion 44a and the explosion-proof valve body. Is electrically connected to
When the battery internal pressure exceeds a predetermined value, the welded portion is peeled off by the deformation stress of the explosion-proof valve body, and the electrical connection between the protruding dish-shaped lid plate and the explosion-proof valve body is cut off. Explosion-proof sealing plate for sealed batteries. 6. A welding method in which a metal explosion-proof valve body 1 and a metal inner terminal plate 3, 23 / or a protruding terminal cover plate 34 / or a protruding dish-shaped cover plate 44 are formed by ultrasonic welding. Part S
Wherein the welding strength is smaller than the breaking strength of the explosion-proof valve body.
6. The explosion-proof sealing plate for a sealed battery according to any one of 4 and 5. 7. An aluminum alloy to which magnesium and / or manganese is added is used as a material of at least one of the constituent materials such as an explosion-proof valve body and an inner terminal plate connected by the welding portion S. Explosion-proof sealing plate for sealed batteries. 8. A material for at least one of the explosion-proof valve body and the inner terminal plate connected by the welded portion S, which has a higher mechanical strength such as tensile strength than an aluminum material and an electrolytic solution. 7. The explosion-proof sealing plate for a sealed battery according to claim 6, wherein a thin layer of aluminum or an aluminum alloy is provided on the welding surface side or on both surfaces of a corrosion-resistant metal having a property as a base material. 9. A battery sealing plate having a built-in function of interrupting an energizing current by a deformation stress of an explosion-proof valve body deforming outward with an increase in battery internal pressure. External terminal plate 5, explosion-proof valve body 1, inner terminal plates 3, 2
3 and lead mounting cover plate 4 / or protruding terminal cover plate 3
4, a sealing plate which is stacked with insulating rings 2 and 32 interposed between the peripheral edges of the explosion-proof valve body and the inner terminal plate and / or the protruding terminal cover plate and accommodated in an insulating gasket 6. The outer terminal plate 5 and the explosion-proof valve body 1 are stacked in an insulating inner gasket 12 and the inner terminal plates 3 and 23 are arranged on the outer peripheral side of the bottom of the inner gasket. An inner gasket which is housed in the dish-shaped lid plate 14 provided with the outer terminal plate 14b or the external terminal plate and the explosion-proof valve body, etc., is provided with a rising portion 44c on the peripheral edge, and a projection 44a is formed near the center of the bottom surface. Protruding dish-shaped lid plate 4
4 is a sealing plate that is formed by bending a rising portion of each lid plate inward and integrally tightening the lid plate, the explosion-proof valve body, the inner terminal plate and / or the protruding terminal cover. The plate and / or the protruding dish-shaped lid plate are electrically connected to each other by a welded portion S or the like formed with metal foils 52 and 62 having a thickness and a mechanical strength smaller than the explosion-proof valve body interposed therebetween. When the battery internal pressure exceeds a predetermined value, the explosion-proof valve body is deformed outward, so that the metal foil body is broken, peeled or the explosion-proof valve body is peeled off, and the electrical connection is cut off. An explosion-proof sealing plate for a sealed battery. 10. An inner terminal plate having a small hole 3c near the center.
10. The explosion-proof sealing plate for a sealed battery according to claim 9, wherein a protruded terminal cover plate or a protruded dish-shaped cover plate is used. 11. The explosion-proof sealing plate for a sealed battery according to claim 1, wherein an inner terminal plate having a thickness and strength greater than that of the explosion-proof valve body is used. 12. The protruding terminal cover plate 34 in which the deformation strength of the periphery of the protrusion is larger than the deformation strength of the pressure receiving surface of the explosion-proof valve body 1.
The explosion-proof sealing plate for a sealed battery according to any one of claims 4 to 10, wherein a protruding dish-shaped lid plate (44) is used. 13. An inner terminal plate 3 and / or a protruding terminal cover plate 34.
The height of each projection of the protruding dish-shaped cover plate 44 is made lower than the thickness of the insulating rings 2 and 32 or the bottom of the inner gasket 12, and the explosion-proof valve body 1 and each of the projections are welded. 13. The explosion-proof sealing plate for a sealed battery according to any one of claims 1 to 12, wherein the explosion-proof valve body is bent and welded to each projection. 14. The explosion-proof valve body 1 wherein mechanically thin portions 1a and 1b are provided on a part of the pressure receiving surface except for a welded portion.
The explosion-proof sealing plate for a sealed battery according to any one of the above. 15. The explosion-proof sealing plate for a sealed battery according to claim 1, wherein a ring-shaped PTC element 72 is arranged between the external terminal plate 5 and the explosion-proof valve body 1.