JPH06215747A - Explosion-proof sealing plate for sealed battery - Google Patents

Abstract

PURPOSE:To prevent the rupture of a battery, by deforming an explosion-proof valve body to be separated from an inner terminal board for interrupting current when battery internal pressure is increased, due to overcharge, reverse charge, and a short circuit, to reach given pressure. CONSTITUTION:An explosion-proof sealing plate 9 is welded and connected to a lead plate 7, introduced from the one-side electrode plate of an electrode plate groove 10, on the surface of a lead fitted lid plate 4, and is calked by a battery case 8 to be sealed after an electrolyte is injected. When battery internal pressure is increased due to overcharge, a short circuit, and reverse charge in a battery, the internal pressure is applied to the inside of an explosion- proof valve body 1 through air vent holes 4a and an inner terminal board 3. In the main body 1, since an outer peripheral part is calked to be fixed to the case 8 via an insulating gasket 6, when the internal pressure reaches a given value, the middle part is swollen upward, a fused part S is separated due to deformation stress, and connection with the inner terminal board 3 is released to interrupt current. Consequently, the rupture of the battery can be prevented.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In recent years, portable and cordless electronic equipment such as AV equipment and personal computers have been rapidly developed, and various alkaline storage batteries having high capacity or lithium secondary batteries have been used as power sources for driving these equipment. There are great expectations for non-aqueous secondary batteries represented by the above as sealed batteries with high energy density and excellent load characteristics. However, due to the failure of the device including the charger or the misuse of the sealed battery, the gas inside the battery becomes abnormal and the internal pressure becomes excessive.
The battery may 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 the inner cover plate of the sealing plate is pressed and closed by an elastic valve body and opened and closed at a predetermined pressure, or an inner cover plate having a thin portion is used. (For example, Japanese Utility Model Publication No. 59-61465), or as shown in FIG. 16, a thin pierceable metal diaphragm (Japanese Utility Model Publication No. 54-137734) or a laminated sheet of metal and synthetic resin (actual When a thin plate-shaped valve element 42a (for example, Japanese Patent Publication No. 59-15398) is integrated with a cap-shaped external terminal lid and the battery internal pressure rises above a predetermined level, the thin plate-shaped valve element bends as shown by a dotted line 42b. However, a non-return type explosion-proof sealing plate is used, which is broken by the blade projection 43 and discharges gas. Both are mainly 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 used as an electrolytic solution and high sealing performance is required.

However, when the above-mentioned sealed type secondary battery having a high energy density is used, if the device is troubled as described above and is charged / discharged by an excessive voltage / current or is externally short-circuited, the energy density of the battery is reduced. In these high batteries, the temperature rises rapidly and a large amount of gas is easily generated.
Even if the above-mentioned explosion-proof sealing plate is provided, the generated gas, electrolyte vapor or the like cannot be exhausted completely, leading to battery rupture. Among the above high energy density batteries, a non-aqueous secondary battery, in particular, a carbon material or lithium or the like is used for the negative electrode, a lithium-containing metal oxide (for example, LiCoO ₂ ) or a metal oxide or the like is used for the positive electrode, and the organic solution is used as the electrolytic solution. A lithium secondary battery using a solvent has such a great risk that the sealing portion may be damaged or the battery may be ruptured due to overcharge, overcurrent charge, external short circuit, or the like.

As one of the countermeasures against the above-mentioned problems, as seen in a cylindrical lithium primary battery used as a driving power source for a camera or the like, a sealing plate or a sealing body of a battery provided with the above-mentioned thin plate valve body is provided. , For example, Japanese Utility Model Publication No. 4-46359,
As disclosed in U.S. Pat. No. 4,855,195 or a conventional example of JP-A-2-207450 (US Pat. No. 4,971,867), a thin ring-shaped or flat-shaped PTC element (PT
C = abbreviation of Positive Temperature Coefficient), there is a method of mounting between the external terminal plate and the cover plate. This PTC
The element is a resistance element with a positive temperature coefficient in which the electric resistance value increases by an order of magnitude when it exceeds a predetermined temperature range due to the flow of current more than a set value, for example, from the trade name "Polyswitch" by Raychem. Some are commercially available.

When the PTC element is built in as described above,
For example, when applied to a battery with a diameter of 14 to 17 mm, PTC
Depending on the configuration conditions of the element, when a large current of about 2.5 to 4 amperes (hereinafter referred to as A) flows, the PTC element reaches the operating temperature in a short time, the resistance value increases, and the conduction current increases. Is significantly reduced and maintained at about 50 to 200 mA. Therefore, it is possible to prevent the battery from being significantly damaged due to an external short circuit or a misuse with an excessive current. However, in the above lithium secondary battery, when an uncontrolled overcharge due to a charger failure or the like, reverse charge, or multiple series overdischarge is performed, the current value is less than the operating current of the PTC element. In many cases, the safe internal current of the battery is exceeded, and the pressure inside the battery rises, causing the break valve to operate.However, if current continues to flow in the battery, the electrolyte and active material may be decomposed. There are many cases where the battery temperature rises sharply to cause ignition or explosive damage, and even if a safety mechanism in which a PTC element is added to the break valve is attached, this problem remains. In order to prevent the phenomenon that an excessive amount of gas or vapor is generated and the battery is destroyed due to an abnormal reaction caused by continuing the improper energization to the battery in this way, the internal pressure of the battery should be detected and the current should be turned on. It is a reliable means to completely cut off the electric current, and some proposals have been made for a battery or an electrolytic capacitor having a similar structure to the battery.
An example is shown below.

US Pat. No. 4,992,344 or 4,937,153
In the double can sealing type battery such as alkaline manganese dry battery, the external terminal plate is contacted and fixed to the bottom of the inner can containing the power generating element by an outer case etc. to conduct electricity. When a large amount of gas is generated inside the inner can due to energization and the bottom of the inner can expands and deforms outward, the contact with the external terminal plate is cut off and the current is cut off. This is to prevent damage to the battery. Further, in the above double can closure method, a ring-shaped reversing spring contact piece whose outer peripheral edge is warped upward is always inserted between the external terminal plate and the bottom surface of the inner can for contact conduction, and the bottom surface of the inner can expands. When deformed, the push-up pressure reverses the reversal spring contact piece to break the contact, and there is a plan to interrupt the current (US Pat. No. 4,028,478).

Further, as seen in US Pat. Nos. 3,617,386 and 5,026,615, an insulating and flexible diaphragm (resin) having a contact terminal (connecting one electrode lead plate on the back side) in the central portion (resin) (Sealing body) and a cap-shaped external terminal plate arranged so as to form a space on the outside thereof to seal the battery container, and at the same time, elastic metal contact with both ends outwardly warped to the space. A structure in which a plate (switch spring) is inserted so that the contact terminal and the external terminal plate are constantly in contact with each other, or in the structure described above, the diaphragm has a contact terminal at the center and a collector for one electrode is provided. It also has a structure in which an annular insulating ring is arranged on the outside of a metal thin plate that also serves as the elastic metal when the gas pressure inside the battery rises and the diaphragm expands and deforms outward. Contact plate is flat 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 resettable valve mechanism for exhausting gas at a predetermined pressure inside the sealing body, a conductive tube disposed at the center of the electrode plate group and connected to the positive electrode cap terminal. The lower end is brought into contact with a positive electrode lead contact insulated from the bottom plate inner surface of the battery container to form a conduction circuit, and when the battery internal pressure rises abnormally, the battery container bottom plate expands and deforms outward, Separate the contact parts,
Some interrupt the conduction circuit (US Pat. No. 3,939,011
issue). As a method different from the above, a pin-shaped lever (projection)
There is one that uses a diaphragm made of an elastic metal with a central part on the outer surface side as an inner lid and covers the upper surface with an external terminal plate provided with a hole through which the lever penetrates to form a sealing body. When using a battery, the battery holder of the device or charger that has an external switch such as a micro switch at its terminal is used, and if the battery internal pressure 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 press the external switch to activate it and cut off the energizing current (US Pat. No. 3,622,397).

On the other hand, also in the electrolytic capacitor, the lead pieces of both electrodes connected to the external terminals provided on the sealing lid are curved and deformed outward by the increase of the internal pressure as a means for preventing the burst damage due to the generation of abnormal gas during energization. There has been proposed a method of cutting the energizing current by cutting with the tension of the sealing lid.

In one form, the other end of a terminal rod, one end of which is fixed to an external terminal which is insulated from the sealing lid, is led out through a through hole of a blocking plate made of a rigid material fixed in the battery container. ,
A weak point is provided by a structure in which the lead plate of the capacitor element is fixed to the tip by welding or the like, or a part of the middle of the terminal rod is thinned, and a flange is provided at the tip led out through the blocking plate. A structure in which the lead plate is fixed to this flange, or a terminal plate provided with an internal terminal on a rigid insulating plate is fixed on the capacitor element, and a cutout is provided between the external terminal and the internal terminal of the sealing lid. For example, there is a metal foil lead plate with weak points formed on each terminal that is fixedly connected by welding, etc.When the gas pressure inside the capacitor rises due to energization and the sealing lid bends outward, 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 separated, or the weak point of the terminal bar breaks to cut off the current, and the latter breaks the metal foil lead plate. Cut off current A shall (Japanese Utility Model 49-105852
Gazette, Japanese Utility Model Publication No. 49-110253, Japanese Utility Model Publication No. 47-11336, etc.).

In another form, the capacitor container is a double case consisting of an outer case provided with external terminals and an inner case with a bottom to prevent external deformation of the capacitor when the internal pressure rises. A metal inner case having a bottom surface on one end face of the capacitor element whose periphery is filled with resin, or a plug-like valve body that closes a hole provided on the bottom surface and moves by gas pressure, and the upper surface thereof. When a gas pressure is generated in the space by covering the inner case made of an insulating material with the lead piece fixed by bridging in an inverted state, the deformation of the bottom surface of the inner case is utilized. , The capacitor element lead piece 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 piece, and the electrical circuit between the capacitor element and the external terminal is broken. There is a proposal to cut off the (Japanese Utility Model 57-2
6835 publication).

[0012] Recently, in order to prevent ignition and explosion that may occur when overcharging or short-circuiting of sealed secondary batteries, especially lithium secondary batteries, a safety device that operates when the internal pressure of the battery rises and shuts off the current. However, JP-A-2-112151, JP-A-2-288063, (US Pat. No. 4,943,497)
Have been proposed. This is the actual exploitation mentioned above 49-105852
The mechanism is similar to the mechanism disclosed in Japanese Patent Publication No. JP-A-2003-138, and instead of the sealing lid, a safety valve that also serves as an inner lid is used, and a lead blocking stripper corresponding to a blocking plate is used. FIG.
18A is a side sectional view of the embodiment before showing the current interruption operation and FIG. 18B shows the state after the operation. As shown in FIG. 18 (A), 82 is a metal safety valve that also functions as an inner lid that deforms outward when the internal pressure of the battery rises, and 84 is a lead cutoff attached to the safety valve via an insulator 83. Stripper 86 is a cap-shaped external terminal plate provided with an exhaust hole 86a, and is a lead plate 87 led out 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 lead blocking stripper. The positive electrode lead plate 87 is the stripper 84.
The lower surface and the projection 82a of the safety valve are bridged. When the gas pressure inside the battery exceeds a predetermined value due to energization such as overcharging, tensile stress is generated in the welded portion as the safety valve is deformed, but the positive electrode lead plate 87 is blocked by the stripper 84, and the positive electrode lead plate 87 is blocked by the stripper 84, as shown in FIG. As shown in (), the safety valve is peeled off or broken off from the projection and the energized current is cut off. Regarding this safety device, an intermediate fitting body made of resin is used, and the safety valve and the stripper are attached by concave and convex fitting to improve the assembly workability (JP-A-2-288063). Further, the stripper is provided with a plurality of ventilation holes, and the surface of the safety valve is provided with a circular arc and a linear thin portion extending outward from the end thereof to improve safety (Japanese Utility Model Publication No. 424262). The improvement plan of is also proposed.

[0013]

If the safety device provided with the above-mentioned current cut-off mechanism is used, continuous overcharging, which cannot be solved by the conventional safety device including the break valve or the PTC element and the break valve, It is possible to solve the problem of battery rupture and ignition caused by reverse charging and the like. However, when the various current interruption mechanisms described above are applied to a small-sized, small-diameter sealed secondary battery that requires high energy density, especially a lithium secondary battery, and it is used in a small electronic device, etc. The external terminal plate of the battery head is deformed, the space efficiency of the blocking mechanism is poor, and the battery energy density is reduced. In addition, reliability is likely to be lowered due to increased circuit resistance due to imperfect contact, destabilization, or disconnection due to drop impact during use. Also,
There were problems such as the production stability of the shutoff mechanism, especially the one in which the assembly quality is likely to deteriorate during mass production of batteries.

The double can closure system shown in US Pat. Nos. 4,992,344 and 4,028,478, which are the first examples of conventional current interrupting mechanisms, have poor volume efficiency and low energy density. Further, when the size is reduced, the contact resistance and the operating state are likely to become unstable due to problems in processing accuracy. A switch method using a warped elastic metal contact plate and a diaphragm, such as the following U.S. Pat.Nos. 5,026,615 and 3,617,386, when applied to a battery with a small diameter, complicates the assembling process and lowers the assembling workability. Resistance tends to be unstable. In addition, the volume occupancy rate of the sealing portion that houses the blocking mechanism tends to increase. The one shown in U.S. Pat.No. 3,939,011 is a method in which the lower end of the conductive tube connected to the cap terminal is brought into contact with the positive electrode lead contact provided on the bottom surface of the battery container, so that it is affected by the accuracy of battery assembly. It is easy to cause poor contact or fluctuation of the breaking operating pressure. In addition, there is a problem that the bottom surface of the battery container or the like is subject to an external impact and causes a failure, or the bottom surface of the battery expands and becomes large at the time of disconnection.

Since the above-mentioned conventional proposals are of the contact conduction type, the contact resistance value is apt to fluctuate under the influence of the accuracy at the time of assembly and the storage environment, and the charge / discharge characteristics in normal use are deteriorated. Therefore, it was unsuitable for batteries requiring high energy density. As a structure different from each of the above examples, the method described in U.S. Pat.No. 3,622,397, which operates the external switch by the movement of the pin lever on the battery side,
Although the battery configuration is simple, it is practically problematic because it does not function except for a dedicated battery holder provided with a switch and remains dangerous.

An actual improvement plan for electrolytic capacitors: Shokai Sho 49
As described in the above-mentioned Japanese Patent Publication No. 105852, since the terminal rod or the metal foil lead plate is peeled off or broken by the bending tension of the sealing lid due to the internal pressure, the conduction failure due to the fluctuation of the contact resistance does not occur. It has been difficult to employ it in a small high energy density battery because the lid is swollen and the outer shape is large, and the dimension in the height direction is large to reduce the volumetric efficiency. Further, the one disclosed in Japanese Utility Model Laid-Open No. 57-26835 is a double-container type in which the sealing lid is not deformed, but the volumetric efficiency is significantly lowered, and therefore it is not practical.

As shown in FIG. 18, the 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 shown in FIG. The safety device occupies a relatively small area as compared with the improved electrolytic capacitor described above, and the curved deformation of the external terminal plate when the safety device is activated (see FIG. 18B) is 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 cutoff operating pressure when the internal pressure of the battery rises serves as the breaking and peeling strength of the welded portion and the cover plate. It is determined by the correlation with the tensile stress of the safety valve, and the fluctuation of the welding strength becomes a large fluctuation factor of the working pressure. Therefore, it is desirable that the welding strength and the strength (thickness, material) of the lead plate be constant, and they cannot be increased so much for ensuring safety. Therefore, when the battery is hermetically closed by using the safety device as a sealing plate, the positive electrode lead plate may have 1 to 2
It is diffracted, pushed into the open end of the battery container through the insulating gasket, and fixed by being bent at the open end of the container. At this time, the bending stress generated in the lead plate is applied to the welded portion as a tensile force and a pressing force, which lowers the welding strength and fluctuates the working pressure, and the welded portion is easily detached.

When this safety device (sealing plate) is applied to a battery using an electrolytic solution mainly composed of a low flash point organic solvent such as the lithium secondary battery, in order to prevent the accidental ignition of the electrolytic solution. As is usually carried out in this type of non-aqueous battery, it is necessary to weld the projection of the safety valve and the lead plate first, and then perform the electrolytic solution injection step to perform the sealing process. However, because of this, the tensile force and pressing force applied to the welded portion are due to the lead bending stress, and further the battery holding in the liquid injection step, and the mechanical stress received from the transfer device, etc. is added, As described above, even if the welding connection strength is set to a constant value, the fluctuation of the current interruption operating pressure becomes large, and the occurrence rate of the non-conducting battery due to the detachment of the welded portion in the assembled battery tends to increase. Further, there are some cases where the current is easily cut off even if the battery is dropped or vibrated during use. As a measure for improving the problems in the process of the safety device, as shown in FIGS. 19 (A) and 19 (B), an aluminum valve led out from a central hole 94b of an aluminum lead blocking stripper 94 is used. In place of the lead plate, a low strength auxiliary terminal plate 95 made of aluminum foil (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 9
Then, a positive electrode lead plate 97 made of aluminum is placed on the upper surface of the auxiliary terminal plate as shown in the drawing, and the positive electrode lead plate 97 made of aluminum is placed on the auxiliary terminal plate surface on the outer peripheral side of the diameter of the hole at points a and b. There is a method of welding and connecting the lead plate, the auxiliary terminal plate, and the stripper with 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. This makes it possible to prevent mechanical stress such as bending stress of the lead plate from directly acting on the spot-welded portion 96 of the valve body projection if the respective welding states are appropriate in the battery assembly process. However, when the battery is mass-produced, the materials, surface conditions, and welding machine conditions of each component fluctuate, and it is difficult to reliably and integrally weld the three components at points a and b. That is, when the welding conditions become weak, the welding between the auxiliary terminal plate and the stripper becomes incomplete, and the auxiliary terminal plate is lifted by peeling off from this part during battery assembly, and the spot welded portion of the valve disc projection is a machine such as a lead plate bent. Receive direct stress. If the welding conditions are too strong, holes are formed in the positive electrode lead plate, the welding strength is reduced, and the lead plate is likely to come off. Thus, the a,
The three-part integrated welding at point b was not sufficiently effective in improving, for example, uneven welding was likely to occur during mass production, and conduction failure occurred during battery assembly or during battery use.

As described above, as an explosion-proof safety function including overcharge of a high energy density sealed battery such as a lithium secondary battery, rupture of the battery due to reverse charging, ignition, etc. It is effective to provide a current interruption mechanism that operates by
There are problems that the outer shape of the battery is deformed, volumetric efficiency is reduced (energy density is reduced), and the like.

In addition, the voltage changes due to poor contact during use of the battery, or the strength of the welded joint decreases during battery assembly, which makes the breaking mechanism unstable and lowers battery reliability. was there.

The present invention is intended to solve such a problem, and an explosion-proof mechanism such as a current interrupting mechanism, which is activated when the internal pressure of the battery is abnormally increased due to overcharge or the like, is incorporated in the sealing plate, and the sealing plate functions independently. By removing the influence of mechanical stress at the time of battery assembly, mass production is facilitated, and in a form suitable for sealed batteries such as lithium secondary batteries, it can withstand shock such as vibration and drop, and is explosion-proof. Excellent in operational stability of the mechanism,
An object is to provide an explosion-proof sealing plate for a sealed battery.

[0023]

In order to solve these problems, the explosion-proof sealing plate of the present invention is provided with a metal explosion-proof valve body (battery internal pressure) which is counter-electroded via an insulating ring or an insulating inner gasket. A thin plate valve body that deforms outward as the temperature rises and an inner terminal plate / or a protruding terminal cover plate / or a protruding plate-like cover plate are provided by ultrasonic welding or the like near the center of each surface. In addition, an explosion-proof function such as a current interrupting mechanism formed by being electrically connected by the welded portion is incorporated in the sealing plate.

The configuration of the sealing plate is as follows: (1) The external terminal plate 5, the explosion-proof valve body 1, the inner terminal plate 3 having a ventilation hole, and the interposing between the explosion-proof valve body and the peripheral edge of the inner terminal plate. The insulating ring 2 and the lead mounting lid plate 4 having a ventilation hole are stacked and housed in the insulating gasket 6, and the explosion-proof valve body and the protrusion 3a provided near the center of the inner terminal plate are arranged. , And electrically connected by the welded portion S to form a current interruption mechanism.

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

(3) External terminal plate 5, explosion-proof valve body 1, and projection terminal cover plate 3 having a vent hole and formed with a projection 34a.
4 and the insulating ring 32 interposed between the explosion-proof valve body and the protruding terminal cover plate are housed in the insulating gasket 6 by stacking them together. The protruding portion is electrically connected by the welding portion S to form a current interruption mechanism.

(4) The outer terminal plate 5 and the explosion-proof valve body 1 are made of an insulating inner gasket 12 having a substantially L-shaped cross section.
Stacked inside, vent hole and rising part 44c
Is housed in a protruding plate-shaped lid plate 44 having a protrusion 44a formed near the center of the bottom surface, and the rising portion of the protruding plate-shaped lid plate is bent inward to be integrally fastened. The explosion-proof valve body and the protruding portion of the plate-like lid plate with protrusions are electrically connected by the welding portion S to form a current cutoff mechanism.

(5) In the structure of the sealing plate according to the above items (1) to (4), a thickness is provided between the explosion-proof valve body and the inner terminal plate / or the protruding terminal cover plate / or the protruding plate-like cover plate. The metal foil bodies 52, 62, which have a lower mechanical strength and a smaller mechanical strength than the explosion-proof valve body, are welded to each other, and are electrically connected by the welded portion S to form a current cutoff mechanism.

(6) In the aspect of the above item (5), the explosion-proof valve body 1 and the inner terminal plate 3 / having a small hole 3c provided near the center thereof
Alternatively, the protruding terminal cover plate 34 / or the protruding dish-like cover plate 4
4, a metal foil body 52 larger than the diameter of the small hole is interposed, and the metal foil body and the inner terminal plate and the like are fixed Sa by welding or adhesion on the outer peripheral side of the small hole, and the metal is 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 mode of the above items (1) to (4), ultrasonic welding is applied as a means for forming the welded portion S when the current interrupting mechanism is constructed, and the welding strength is the explosion-proof. It should be smaller than the breaking strength of the disc.

When an aluminum material is used as the constituent member to be welded, an aluminum alloy containing magnesium and / or manganese is preferably used as the material of one or both members, or the mechanical strength is higher than that of the aluminum material. A composite metal material having a large thickness and a 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-like cover plate is used in which the deformation strength near the center is greater than the deformation strength of the pressure receiving surface of the explosion-proof valve body.

The height of each protrusion provided on the inner terminal plate, the protruding terminal cover plate, or the protruding plate-like cover plate is made lower than the thickness of the bottom of the insulating ring or the inner gasket so that the explosion-proof valve body can be used for welding. Bend each side of the protrusion and weld.

(8) A conductive sealing agent is interposed between the inner terminal plate shown in the above (1) and (2) and the contact surface of the lead mounting cover plate or the dish-shaped cover plate by coating or the like. .

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

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

[0037]

By using the explosion-proof sealing plate having such a structure, when the battery is in an abnormal use state such as overcharge, reverse charge, external short circuit, etc., and the internal pressure of the battery rises to reach a predetermined pressure, the explosion-proof valve is opened. Due to the stress that the body deforms outward (external terminal side), the explosion-proof valve body is peeled off or the metal foil body is ruptured from the welded part with the inner terminal plate or the protruding terminal cover plate or the protruding plate-like cover plate. Then, the electrical connection is cut off by peeling. By this current interruption operation, it is possible to prevent a rapid temperature rise, rupture, and explosion of the battery due to energization without causing a deformation of the appearance of the battery or a decrease in volumetric efficiency.

Further, by providing the inside of the explosion-proof sealing plate with a current blocking function, it is possible to strengthen the connection between the lead plate led out from the electrode and the explosion-proof sealing plate by welding or the like. It is possible to solve problems such as defective assembly during assembly.

Furthermore, 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 is performed, so that troubles such as connection failure do not occur during use of the battery. When the battery internal pressure reaches a predetermined value, the explosion-proof valve body can be peeled off, and the current cutoff operation can be reliably performed.

As described above, by applying the explosion-proof sealing plate of the present invention, it is possible to produce a sealed battery with high safety and reliability.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1, 2 and 3 are views showing an explosion-proof sealing plate for a sealed battery according to the first aspect of the present invention. The explosion-proof sealing plate 9 is made of a flexible thin metal explosion-proof valve body 1, an insulating ring 2, an inner terminal plate 3 made of metal having a protrusion 3a in the center and having a ventilation hole 3b, and made of metal. 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 on the upper side of 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 its center by ultrasonic welding, resistance welding, laser welding or the like. Then, the welded portion S is formed and electrically connected.

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

The explosion-proof sealing plate is welded and connected to the surface of the lead mounting lid plate 4 on the lower surface side with the lead plate 7 derived from one of the electrode plates of the electrode plate group 10, and the electrolyte solution is connected to the electrode plate group. After the injection, the battery case 8 is mounted inside the opening, and the upper end of the battery case 8 is caulked and tightened as shown to seal the battery.

When gas, vapor, etc. are generated in this battery due to improper energization such as overcharging, short-circuiting or reverse charging, and the battery internal pressure rises, the battery internal pressure is increased by the lead mounting lid plate and the inner terminal plate. It is applied to the inside of the explosion-proof valve body 1 through the vent holes 4a and 3b provided in the. Since the outer peripheral portion of the explosion-proof valve body 1 is crimped and fixed by the battery case 8 via the insulating gasket 6, when the battery internal pressure reaches a predetermined value, as shown in FIG. 3 (B). The central portion bulges upward, and the welded portion S is peeled off due to the deformation stress at that time, the connection with the inner terminal plate 3 is released, and the energizing current is cut off.

(Embodiment 2) FIG. 4, FIG. 5 and FIG. 6 are views showing the configuration mode 2 of the present invention. The same external terminal plate 5 and explosion-proof valve body 1 as those described above are stacked and placed in an insulating inner gasket 12 formed by molding a resin such as polypropylene in an approximately L-shape in an annular shape and at the bottom of the inner gasket. An inner terminal plate 3 having a ventilation hole 3b is arranged on the outer peripheral surface, and the inner terminal plate 3 (see FIG. 4) is provided near the center of the explosion-proof valve body 1.
In (A), the protrusion 3a is welded to the upper surface of the protrusion 3a by ultrasonic welding or the like to form a welded portion S, and both are electrically connected.

After these are placed and housed in a metal dish-shaped lid plate 14 having a ventilation hole 14a and a rising portion 14b at the periphery, the rising portion 14b of the dish-shaped lid plate is bent and caulked inward. The explosion-proof sealing plate 11 is formed by forming the portion 14c and fastening them together. FIG. 5B shows an example of a method of connecting the explosion-proof valve body and the inner terminal plate by ultrasonic welding.

The bottom surface of the inner terminal plate 3 is fixed to the fixing base (anvil) A.
The explosion-proof valve body 1 placed on the v plate and housed in the inner gasket 12 is placed thereon and connected to an ultrasonic transducer.
By adjusting the load at the tip of the Hq valve and pressing it near the center of the explosion-proof valve body, and applying ultrasonic vibration (for example, 40 KHz), welding is performed by frictional heat on each surface of the explosion-proof valve body and the inner terminal plate. Then, the welded portion S is formed.

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

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

Next, the inorganic solute is replaced with ethylene carbonate,
An annular rib provided with the explosion-proof sealing plate 11 near the open end of the battery case after injecting a predetermined amount of non-aqueous electrolyte solution dissolved in propylene carbonate or other single or composite organic solvent, and bending the positive electrode lead plate. 15a, and then crimp the open end of the battery case inward (1
By doing 5b), a sealed battery is obtained.

(Third Embodiment) The above-mentioned first and second embodiments.
5, the aluminum powder or the silver powder is dispersed in a resin solution such as an acrylic resin between the inner terminal plate 3 and the dish-shaped cover plate 14 or the lead mounting cover plate, as shown by 14e in FIG. 5 (A). The explosion-proof sealing plate is formed by interposing the conductive sealing agent described above by coating. As a result, even if a material having a large surface contact resistance such as stainless steel is used as the material of the metal parts, the contact surface resistance value can be reduced, and the voltage drop loss at the time of high rate discharge can be reduced. Further, there is an effect that the sealing property of the metal contact portion between the inner terminal plate and the lead mounting lid plate in Example 1 is enhanced, and the liquid leakage resistance of the battery is further improved.

(Embodiment 4) FIG. 7 shows a third embodiment of the present invention.
It is a figure which shows the side cross section of the explosion-proof sealing plate 31 of FIG. In this embodiment, instead of the inner terminal plate 3 and the lead mounting cover plate in the first embodiment, as shown in the drawing, the ventilation hole 34b and the protruding portion 34a are provided.
In this embodiment, a protrusion-type terminal cover plate 34 provided with is used as an insulating ring interposed between the protrusion-type terminal cover plate 34 and the explosion-proof valve body 1, and a polyolefin-based heat-sensitive adhesive (hot melt adhesive A material provided with an adhesive layer 32a is used, and after the three members are integrated by thermocompression bonding or the like, the welded portion S is formed. As a result, the airtightness between the protruding terminal cover plate 34 and the peripheral edge of the explosion-proof valve body 1 can be completely made, and the airtightness and liquid leakage resistance as the sealing plate can be further improved.
This embodiment is suitable for a battery having a relatively small diameter.

(Embodiment 5) FIG. 8 shows a fourth embodiment of the present invention.
It is a figure which shows the side cross section of the explosion-proof sealing plate 41 of FIG. This is to integrally replace the inner terminal plate 3 and the dish-shaped cover plate 14 shown in the second embodiment. Instead of the both members, the ventilation hole 4 is provided.
4b and a rising portion 44c on the periphery, and a protruding plate-shaped lid plate 44 having a protruding portion 44a formed near the center of the bottom surface as shown in the figure is used. When the explosion-proof sealing plate of this aspect is applied, for example, for a small battery having a diameter of 15 mm or less,
No particular consideration is given to the material of the plate-like lid plate with protrusions, but when the outer diameter is large, a material with greater rigidity or a metal material with an increased thickness compared to the plate-like lid plate of Example 2 is used. It is preferably applied.

This is to prevent fluctuations in the current cutoff pressure due to bending of the central portion during caulking and assembling.

In the configuration modes 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, various metal materials can be used as the metal material forming the welded portion S such as the protruding plate-like lid plate as described in the second embodiment. Which is connected, battery voltage, current cutoff set pressure,
Determine the material and thickness in consideration of the welding method. In the sealed alkaline battery system, a metal material having stable weldability such as a steel plate having a nickel thin layer on its surface, a nickel thin plate, or a nickel alloy thin plate can be used.

In the sealed non-aqueous secondary battery such as a lithium type battery in which the present invention exerts a remarkable effect, as described in Example 2, the corrosion resistance, the reduction of the electric resistance value, the stability of the welding and the like are caused. The aluminum-based metal material is easy to use, and a combination of specific aluminum alloy materials is preferable, as will be 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 plate-like cover plate are used when the internal pressure of the battery rises above a predetermined value. This is a method of releasing the connection by the welded portion S. Therefore, it is necessary to surely separate the welded portion before the explosion-proof valve body 1 is damaged or damaged including fine holes. Therefore, the welding condition is set so that the welding strength of the welding portion S is smaller than the damage strength of the explosion-proof valve body 1. When the aluminum material described in the second embodiment is used, ultrasonic welding, pressure welding by pressure, or the like can be applied, but a welded portion that reliably peels with stable strength including matching with the current cutoff pressure. Ultrasonic welding is preferred for forming the.

Further, in order to surely cut off the electric current, the inner terminal plate 3 or the projecting portion having a greater 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. Projected terminal cover plate 3 with a large peripheral edge deformation strength
4. It is preferable to use the protruding plate-shaped lid plate 44. As a result, when the internal pressure of the battery rises, the inner terminal plate and the like 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 or the like is set to be approximately 1.5 times or more that of the explosion-proof valve body.
In the case of an inner terminal plate, a material that is large in both thickness and strength is preferable, and in the case of a terminal plate with protrusions, the deformation strength of its periphery, including the influence of the molding shape of the protrusions, is the strength of the explosion-proof valve body. A material that is 1.5 to 2 times or more is used.

Furthermore, in the configuration modes of Examples 1 to 5 described above, the explosion-proof valve body 1 and the inner terminal plate 3 or the protruding terminal cover plate 3 are used as in the case of the above-mentioned sealed lithium secondary battery.
4 or when the aluminum base material is used as the material of the protruding plate-like lid plate 44, if the ultrasonic welding method as shown in FIG. It is possible to reliably peel off and stably perform the current interruption operation.

If the aluminum material to be used is selected according to the set values of the current cutoff pressure and the rupture pressure at the time of abnormal overpressure of the explosion-proof valve body, the assembly construction of the explosion-proof sealing plate becomes easier.
When the explosion-proof valve has a breaking pressure of 20 to 30 Kgf / cm ² or higher and a current breaking pressure of 15 Kgf / cm ² or higher, such as a high operating pressure, a pure aluminum system (JIS 1000 series) that is generally used as a foil or thin plate material. A1050, AIN
30 etc. are applicable. However, the current cutoff pressure varies depending on the applied battery system and its configuration 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, it becomes difficult to adjust with a pure aluminum material, and the breaking pressure fluctuation tends to increase. The correspondence is shown below.

(Embodiment 6) As a constituent material of the explosion-proof valve body used in the above-mentioned Embodiments 1 to 5 and the inner terminal plate, the protruding terminal cover plate or the protruding dish-like cover plate, at least one side to be welded Aluminum alloy added with magnesium or manganese, or both, for example, Al-Mg alloy (A5005, A50
52) or Al-Mn-based A3003, A320
3, A3004, A3105, A containing Al, Mn
The alloy thin plate or foil such as 5454 is used. However, the amount of magnesium added is preferably selected from the range of about 0.5 to 3% (in the case of an excessively added product, the welded part may be embrittled with time). Since the welding strength of the alloy to which magnesium or manganese is added can be adjusted over a wide range by ultrasonic welding, stable pressure peeling can be performed even if the current cutoff pressure is lowered. When it is set to about 3 to 5 Kgf / cm ² , it is advisable to use the above alloy material for both the constituent materials.

Instead of the above-mentioned aluminum alloy, a composite metal material in which a thin layer of an aluminum material is provided on the surface of a corrosion resistant substrate such as a stainless steel plate by the Clatt method is used.

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 sealing plate constructions of the first to fifth embodiments.
Between the explosion-proof valve body 1 and the inner terminal plate 3, the protruding terminal cover plate 34, or the protruding dish-like cover plate 44, the thickness and mechanical strength (rigidity, hardness) are smaller than those of the explosion-proof valve body. Metal foil body 5
The welded portion S is formed with 2, 62, 63 and 64 interposed. Taking an example of using an aluminum-based material as each constituent material, the thickness of the metal foil body is about 0.1 to 0.5 times the thickness of the explosion-proof valve body and has a mechanical strength (tensile strength). Etc.) are the same or less. As an example, the explosion-proof valve body has a thickness of 0.15 mm A3003 or A1N3.
0, and a foil body 52, 62, etc., with a thickness of 0.05 mm A
A semi-hard or smooth material such as 1050 or A1N30 is used. The inner terminal board 3 etc. 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, the aluminum foil body 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. Then, the welded portion S is formed by ultrasonic welding. Figure 1
The first example is a metal foil body shown in (A) 62 having an arcuate cutout portion 62a in (B) 62, a large foil cutout portion 63a and a cutout 63b in (C) 63,
The small cutout portion 64b and the arc-shaped thin portion 6 as shown in FIG.
4 is provided with 64a and the like, and is adhered Sa to the back surface of the explosion-proof valve body 1 by a conductive adhesive or brazing to assemble, and welded to form the welded portion S.

(Embodiment 8) FIG. 10 shows an embodiment of the sixth aspect of the present invention, in which the embodiment 7 can be applied to a lower current breaking pressure. As shown in (A), the vent holes 3b and the small holes 3c (1.
3d of the small hole peripheral edge of the inner terminal plate 3 provided with about 5 to 5 mm)
As in the case of the seventh embodiment, an aluminum foil having a thickness of about 0.05 mm is used as the metal foil body 52, and is fixed by spot welding, laser welding, ultrasonic welding, or a conductive adhesive.
After a, as shown in (B), the explosion-proof valve body 1 and the foil body 52 are welded to each other by ultrasonic welding or the like through the small diameter 3c of the inner terminal plate.
Are formed and connected. In addition to the inner terminal board,
Even when the protruding terminal cover plate 34 and the protruding dish-shaped cover plate are used, the same operation can be performed by providing appropriate small holes. In this mode, since the metal foil body is peeled off or broken and the current interruption operation is performed, by selecting the thickness and mechanical strength of the metal foil body, it is possible to stabilize even at a low pressure of ^{3 to 5} Kgf / cm ^2. Current can be cut off.

Further stable effects can be obtained by properly using the explosion-proof sealing plate of each embodiment described above according to the shape and size of the battery. That is, the one using the lid plate having no rising portion on the peripheral edge of the first and fourth embodiments is a battery having a relatively small diameter and small size, and the dish-like lid having the rising portion on the peripheral edge of the second and fifth embodiments. The caulking and assembling method using a plate is suitable for a battery having a large diameter or an elliptical shape because each member is fixed in the sealing plate and the overall strength can be maintained.

Further, in the construction of each of the above-mentioned modes, when the explosion-proof valve body 1 is made of a thin and soft material, when the internal pressure of the battery rises and the welded portion is peeled off, it becomes wavy due to the internal pressure fluctuation. In order to prevent incomplete disconnection from the inner terminal plate, the height d of the protrusion 3a of the inner terminal plate 3 is set to the thickness of the insulating ring 2 as shown in the sectional view of FIG. D
Lower than 2, the explosion-proof valve body 1 is bent toward the protrusion when welding to form the welded portion S. The same configuration is also applied to other examples using the protruding terminal cover plate 34, the protruding dish-like cover plate 44, and the inner gasket 12.

In the second embodiment, the inner terminal plate 3 is
When the inner gasket has a small wall thickness, it may be configured such that a protrusion is not provided as shown in FIG. 13 and a warp is provided slightly upward. If the explosion-proof valve body is bent and welded as shown in FIG.
The same effect as described above can be obtained.

Further, the explosion-proof valve body 1 used in the present invention has not only the function of shutting off the current, but also the function of preventing the battery from exploding by being partially broken by the internal pressure when the battery is put in a fire or abnormally heated. However, by forming the welded portion S, the breaking working pressure tends to increase.
Therefore, when the battery sealing strength is low,
As shown in a or 1b of FIGS. 4 and 5, it is preferable to adjust the breaking pressure of the explosion-proof valve body to be low by providing a thin-walled portion such as an arc by machining. The operating condition is indicated by 1x in FIG.

Furthermore, FIG. 14, FIG. 7, FIG.
By inserting a ring-shaped PTC element such as "PolySwitch" (trade name) manufactured by Raychem Co., Ltd., as shown at 72 in (A), between the external terminal plate 5 and the explosion-proof valve body 1, a battery can be obtained. The battery can be economically used because it operates immediately when an external short circuit or an excessive current is applied to ensure the safety of the battery before the operation of the current interruption function.

Next, the sealed lithium secondary battery (AA type, 3.7V, 550 mAh) shown in Example 2 of the present invention was used in Example 6 in the mode of Example 2 (FIG. 4) of the present invention. The battery according to the present invention sealed by using the explosion-proof sealing plate 11 having the metal material structure (aluminum alloy) and the conventional battery sealed by using the explosion-proof sealing plate (laminate sheet valve body) shown in FIG. Continuous charging (5 each) at a current of 1A (ampere) was performed in a room at about 25 ° C.
5 and FIG. As can be seen from both figures, when the amount of electricity charged in this battery exceeds 100% of the nominal capacity, heat generation and the battery internal pressure start to rise rapidly, and when it exceeds 200%, the battery internal pressure is 15 to 20 Kgf / cm ² Reach At this point, in the conventional explosion-proof sealing plate, the thin valve element 42a is broken (vented), and the generated gas is exhausted. However, charging continued, and when the battery temperature reached 100 to 120 ° C., a sudden abnormal reaction occurred and the battery exploded (marked with a cross in FIG. 17).
However, in the battery equipped with the explosion-proof sealing plate of the present invention, as shown in the figure, when the battery internal pressure is 15 Kgf / cm ² , the current interruption function is activated to cut off the current, and the temperature rise and the gas generation are stopped. , The safety of the battery is secured.

Further, the state of occurrence of defects during assembly of the explosion-proof sealing plate and battery production was examined, and the case where the explosion-proof sealing plate of the present invention was adopted and the conventional explosion-proof sealing plate shown in FIG. With respect to the one shown in FIG. 19, 2000 pieces each were assembled and assembled in a battery with a current cutoff operating pressure / reference value of about 12 Kgf / cm ² , and a drop test from a height of 1 m was carried out. In the case of 4 cells, disconnection occurred, but in the case of the present invention, there was no disconnection. Further, an overcharge test was carried out for each 20 cells of the battery after the test while measuring the battery internal pressure. As a result, is 9.5 to 14 Kgf / cm ² , and 7 to
At 19 Kgf / cm ² , it was 8 to 17 Kgf / cm ² .

In the lithium secondary battery system described above, the set value of the current cutoff operating pressure varies depending on the prescription of the battery, the constitutional conditions, etc., and in many cases, high accuracy is required. In addition to the above-mentioned examples of the present invention, those of Example 8,
And the above-mentioned conventional example, the current cutoff operating pressure
Assembling 1000 pieces each with a standard value of 6.5 Kgf / cm ² .
Assembled as a battery, each 30 cells were taken out, and the current cutoff operating pressure was examined by overcharging.

As a result, in the case of the present invention, 4.7
˜9.5 Kgf / cm ² , 5.8 to 7.5 K in the case of Example 8.
gf / cm ² , the conventional example is 1.5 to 13 Kgf / cm
^The width was widened to ² and the number of breaks exceeded 10%. The conventional example 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, or the PTC is used.
By incorporating the element in the sealing plate, safety against abnormal heating such as being thrown into fire other than energization, and making the battery safe and reusable when excessive current flows due to short circuit etc. be able to. Further, since the explosion-proof sealing plate of the present invention has all the current blocking function and the explosion-proof safety functions such as the rupture valve and the PTC element incorporated in the sealing plate, the road condition and the lower limit working pressure are measured before the battery is assembled. Therefore, it is possible to provide a more accurate explosion-proof sealing plate.

[0077]

EFFECTS OF THE INVENTION 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 burst of the battery at the time of abnormal current flow such as overcharge, reverse charge and short circuit of the battery. It is possible to obtain a highly reliable sealed battery whose quality at the time of production is stable and which does not easily cause malfunction even when shock such as vibration and drop is applied.

[Brief description of drawings]

FIG. 1 is a 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. FIG.

FIG. 3 (A) is an explanatory view of an operating state of a battery using the explosion-proof sealing plate of Example 1 (B) is an explanatory view after the same operation

FIG. 4 (A) is a sectional view of the structure of the explosion-proof sealing plate according to the second embodiment of the present invention.

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

FIG. 6 is a cross-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 Example 4 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. 9A is a view showing the structure of the explosion-proof sealing plate according to another structure method of Examples 1 to 5 of the invention. FIG. 9B is the same sectional view.

FIG. 10 (A) is an assembly view showing an explosion-proof sealing plate according to another construction method of embodiment 7 of the present invention (B) same sectional view

11A is a cross-sectional view of a sealing plate according to another configuration method of Examples 1 to 5 of the present invention. FIG. 11B is an assembly diagram of an explosion-proof valve body. FIG. 11C is a diagram showing a metal foil body. Showing

FIG. 12 is a view showing constitutional conditions in the explosion-proof sealing plate of Examples 1 to 5 of the present invention.

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

FIG. 14 is a sectional view of a PTC element incorporated in the explosion-proof sealing plate according to the 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.

FIG. 18 (A) is a cross-sectional view of a battery using a conventional explosion-proof sealing plate having a current interruption function, and (B) is a cross-sectional view of essential parts showing the same operating state.

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

[Explanation of symbols]

 1 Explosion-proof valve body 2 Insulation ring 3 Inner terminal plate 4 Lead mounting lid plate 5 External terminal plate 6 Insulation gasket 7 Lead plate 8 Battery case 9 Explosion-proof sealing plate 11 Explosion-proof sealing plate 12 Inner gasket 14 Plate-shaped Lid plate 15 Battery case 17 Electrode plate group 18 Lead plate 21 Explosion-proof sealing plate 23 Inner terminal plate 31 Explosion-proof sealing plate 32 Insulation ring 34 Protruding terminal lid plate 35 Sealant 41 Explosion-proof sealing plate 44 Protruding dish-like 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 portion 1b Thin portion 3a Projection portion 3b Vent hole 3c Small hole 4a Vent hole 5a Exhaust hole 14a Vent hole 23b Vent hole 34a Projection part 34b Vent hole 44a Projection part 44b Vent hole 63b Notch 64a Thin part d Central projection height d2 Insulation ring thickness Sa Wearing portion S welded portion

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yukimasa Niwa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (72) Inventor, Mamoru Iida 1006 Kadoma, Kadoma City, Osaka Matsushita Electric Industrial Co., Ltd. 72) Inventor Yasushi Hirakawa 1006 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (15)

[Claims] 1. An electrode group consisting of a positive electrode plate, a negative electrode plate and a separator, and a sealing plate for sealing a battery case containing an electrolytic solution. The sealing plate is made of a metal external terminal plate 5 and a battery internal pressure. Explosion-proof valve body 1 made of metal that deforms outward as it rises
And an inner terminal plate 3 made of metal and having a vent 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 lid plate 4 made of metal and having a vent hole 4a
Are stacked and housed in an insulating gasket 6, and the inner terminal plate 3 is electrically connected to the explosion-proof valve body by a welding portion S between the protrusion 3a provided near the center of the inner terminal plate 3 and the explosion-proof valve body 1. When the battery internal pressure exceeds a predetermined value, the explosion-proof valve body is deformed outward so that the welded portion is peeled off and the electrical connection between the inner terminal plate and the explosion-proof valve body is cut off. An explosion-proof sealing plate for hermetically sealed batteries, characterized in that 2. A terminal member such as a metal external terminal board 5,
An explosion-proof valve body 1 made of metal, which is deformed outwardly as the internal pressure of the battery rises, is provided with an insulating inner gasket 1 having a substantially L-shaped cross section.
2, and the inner terminal plates 3 and 23 made of metal and having ventilation holes are arranged on the outer peripheral surface side of the bottom portion of the inner gasket,
This is housed in a metal dish-shaped lid plate 14 having a vent hole 14a and a rising portion 14b at the periphery, and the rising portion of the dish-shaped lid plate is bent inward and tightened integrally. The inner terminal plate is a plate, and the welded portion S with the explosion-proof valve body is provided near the center thereof.
However, when the battery internal pressure exceeds a predetermined value, the welded portion is peeled off due to the deformation stress of the explosion-proof valve body, so that the internal terminal plate and the explosion-proof valve body are electrically connected. An explosion-proof sealing plate for a sealed battery, characterized in that it is configured to cut off a physical connection. 3. The conductive sealant is interposed between the contact surfaces of the metal inner terminal plates 3 and 23 and the lead attachment cover plate 4 or the dish-like cover plate 14 according to claim 1 or 2. Sealing plate for sealed batteries. 4. A terminal member such as a metallic external terminal board 5,
Explosion-proof valve body 1 made of metal, which deforms outwardly as the internal pressure of the battery rises, metal projection terminal cover plate 34 having a vent hole 34b and a projection 34a formed near the center, and the explosion-proof valve. Insulation ring 3 interposed between the body and the peripheral edge of the protruding terminal cover plate
2 is stacked and housed in an insulating gasket 6, and the protruding terminal cover plate 34 is electrically connected to the explosion-proof valve body by a welded portion S between the protrusion 34a and the explosion-proof valve body 1. When the battery internal pressure exceeds a predetermined value, the welding portion is peeled off due to 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. Explosion-proof sealing plate for sealed batteries. 5. A terminal member such as a metallic external terminal board 5,
The explosion-proof valve body 1 made of metal, which is deformed outward as the internal pressure of the battery rises, is stacked in the insulating inner gasket 12,
This is housed in a metal projection plate-shaped lid plate 44 having a ventilation hole 44b and a rising portion 44c at the periphery and having a projection portion 44a formed near the center of the bottom surface, and the rising portion of the projection plate-shaped lid plate. 44C is a battery sealing plate in which 44c is bent inward and is integrally fastened, and the protruding plate-like lid plate 44 has an explosion-proof valve body by a welded portion S between the protrusion 44a and the explosion-proof valve body. Electrically connected to
When the battery internal pressure exceeds a predetermined value, the welded portion is peeled off due to the deformation stress of the explosion-proof valve body, and the electrical connection between the plate-shaped lid plate with projection 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 plate-like cover plate 44 are formed by ultrasonic welding. Department S
And the welding strength is smaller than the breaking strength of the explosion-proof valve body.
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 on at least one side of each constituent material such as an explosion-proof valve body and an inner terminal plate connected by a welded portion S. Explosion-proof sealing plate for sealed batteries. 8. A material for at least one of the components such as the explosion-proof valve body and the inner terminal plate, which are connected by the welded portion S, has a mechanical strength such as a tensile strength larger than that of an aluminum material and an electrolytic solution resistant. The explosion-proof sealing plate for a hermetically sealed battery according to claim 6, wherein a corrosion-resistant metal having heat resistance is used as a base material and a thin layer of aluminum or an aluminum alloy is provided on both sides of the welding surface. 9. A battery sealing plate having a built-in function of interrupting an energization current due to a deformation stress of an explosion-proof valve body that is deformed outward with an increase in battery internal pressure, the configuration of which is (1) 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) and a sealing plate which is housed in an insulating gasket (6) by stacking the insulating ring (2, 32) interposed between the explosion-proof valve body and the inner terminal plate / or the protruding terminal cover plate on the periphery. The outer terminal plate 5 and the explosion-proof valve body 1 are stacked in an insulative inner gasket 12, and the inner terminal plates 3 and 23 are arranged on the bottom outer peripheral surface side of the inner gasket. An inner gasket, which is housed in a dish-shaped lid plate 14 provided with 14b or is stacked with the external terminal plate and the explosion-proof valve body, is provided with a rising portion 44c at the periphery and a protrusion 44a is formed near the center of the bottom surface. Plated lid plate with protrusion 4
4 is a sealing plate that is housed in a housing 4, and the rising portions of the respective cover plates are bent inward and integrally fastened, and the explosion-proof valve body and the inner terminal plate / or the protruding terminal cover are provided. It is electrically connected to the plate and / or the plate-like lid plate having a projection by a welded portion S formed by interposing metal foil bodies 52 and 62 having a thickness and mechanical strength smaller than that of the explosion-proof valve body therebetween. When the internal pressure of the battery exceeds a predetermined value, the metal foil body is broken or peeled or the explosion-proof valve body is peeled off by the stress that the explosion-proof valve body is deformed outward, so that the electrical connection is cut off. An explosion-proof sealing plate for sealed batteries, which is characterized in that 10. An inner terminal plate having a small hole 3c near the center thereof.
Alternatively, the explosion-proof sealing plate for a hermetically sealed battery according to claim 9, wherein a projecting terminal cover plate / or a projecting dish-like cover plate is used. 11. The explosion-proof sealing plate for a hermetically sealed battery according to claim 1, wherein the inner terminal plate is thicker and stronger than the explosion-proof valve body. 12. The protruding terminal cover plate 34, wherein the deformation strength of the periphery of the protrusion is larger than that of the pressure receiving surface of the explosion-proof valve body 1.
Alternatively, the explosion-proof sealing plate for a hermetically sealed battery according to any one of claims 4 to 10, which uses a protruding plate-shaped cover plate 44. 13. The inner terminal plate 3 and / or the protruding terminal cover plate 34.
/ Or the height of each protrusion of the protruding plate-like lid plate 44 is made lower than the thickness of the bottom of the insulating ring 2, 32 or the inner gasket 12 to weld the explosion-proof valve body 1 and each protrusion. At this time, 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 side. 14. The thin wall portions 1a and 1b are mechanically provided on part of the pressure receiving surface of the explosion-proof valve body 1 excluding the welded portion.
An explosion-proof sealing plate for a sealed battery according to any one of 1. 15. The explosion-proof sealing plate for a hermetically 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.