JP2006066269A - Sealed-type storage battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealed-type storage battery, in which generation of a large electric current at short circuit is prevented and in which safety is improved by providing a sealed body with a PTC element and by arranging a pressure valve at a prescribed position, without reducing the volume inside the exterior can. <P>SOLUTION: The sealed body 10 is constituted of a bottom plate 11 for sealing the opening part of the sheath can 18, a cathode cap 12 which serves as a cathode terminal and which forms a space part that houses the pressure valve in its interior, an insulating ring 13, an elastic valve 14 in which a steel plate 14a is provided to the upper face, a spring 15, and a PTC element ring 16 arranged on a flange 12a of the cathode cap 12. Then, a protruding part 11b for positioning the elastic valve 14 for sealing an exhaust port 11a formed at the center part of the bottom plate 11 is formed so as to protrude from the bottom plate 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention insulates an electrode group in which a positive electrode and a negative electrode are wound via a separator, an outer can that houses the electrode group and also serves as a terminal of one electrode, and an opening of the outer can The present invention relates to a sealed storage battery that also serves as a terminal of the other electrode that is sealed through a gasket and includes a sealing body that incorporates a pressure valve, and particularly relates to a sealed storage battery that includes a PTC element in the sealing body.

  Generally, a sealed storage battery such as a nickel-hydrogen storage battery or a nickel-cadmium storage battery has an operating voltage of about 1.2 V at the time of discharge. Therefore, in a so-called AA size or AAA size battery, a manganese dry battery or an alkaline primary battery is used. It may be used for interchangeability of AA type or AA type such as (alkaline battery). However, when the battery is misused, such as external short circuit or reverse insertion, manganese batteries and alkaline batteries have low output characteristics, so that a large current does not flow. However, the sealed storage battery as described above has a problem in that a large current can be discharged, so a short circuit current is large, and heat generation or burning due to a large current occurs.

  In order to prevent this kind of heat generation and burning due to a large current, in a lithium ion battery, when the temperature rises, the resistance value increases and a PTC (Positive Temperature Coefficient) element that suppresses the large current or the large current is cut off. A breaker is built in. For example, Patent Document 1 proposes that a PTC element is arranged at the bottom of an outer can that also serves as a positive electrode terminal. However, when the PTC element is disposed at the bottom of the outer can, the entire length becomes longer by the thickness of the PTC element, or the PTC element is exposed to the outside, which causes a problem that the PTC element is detached. Therefore, for example, Patent Document 2 has proposed that a PTC element is disposed in a sealing body having a valve body.

  A sealing body incorporating such a PTC element has a structure as shown in FIG. 3, for example. The sealing body 30 shown in FIG. 3 includes a stainless steel positive electrode cap 31 formed in a cap shape and a stainless steel bottom plate 34 formed in a dish shape. The positive electrode cap 31 includes a convex portion 32 that bulges toward the outside of the battery and a flat flange portion 33 that forms the bottom side of the convex portion 32, and a plurality of gas vents are formed at the corners of the convex portion 32. A hole 32a is provided. On the other hand, the bottom plate 34 includes a recess 35 that bulges toward the inside of the battery and a flat flange portion 36 that forms the bottom side of the recess 35, and a gas vent hole 35 a is provided at a corner of the recess 35. It has been.

  Housed in the positive electrode cap 31 and the bottom plate 34 is a power derivation plate 37 that is deformed when the gas pressure inside the battery rises and exceeds a predetermined pressure. The power lead-out plate 37 includes a concave portion 37a and a flange portion 37b, and is made of an aluminum foil. The lowest portion of the concave portion 37a is disposed in contact with the upper surface of the concave portion 35 of the bottom plate 34, and the flange portion 37b is sandwiched between the flange portion 33 of the positive electrode cap 31 and the flange portion 36 of the bottom plate 34. Yes. The positive electrode cap 31 and the bottom plate 34 are sealed in a liquid-tight manner by a sealing body insulating gasket 39 made of polypropylene (PP).

A PTC (Positive Temperature Coefficient) element 38 is disposed on the upper part of the flange portion 37b. When an overcurrent flows in the battery and an abnormal heat generation occurs, the resistance value of the PTC element 38 increases and the overcurrent is increased. Decrease. Then, when the gas pressure inside the battery rises and exceeds a predetermined pressure, the recess 37a of the power lead-out plate 37 is deformed, so that the contact between the power lead-out plate 37 and the recess 35 of the bottom plate 34 is cut off and an overcurrent or short circuit occurs. The current is interrupted.
JP-A-2-207450 Japanese Patent No. 3143176

  Incidentally, in an alkaline storage battery using a sealing body that does not contain a PTC element, as shown in FIG. 4, the thickness of the outer periphery of the sealing body 40 (the portion that is caulked to the outer can 47 via the insulating gasket 46) is reduced. Therefore, the battery capacity is increased as much as possible to increase the discharge capacity. That is, the sealing body 40 shown in FIG. 4 includes a positive electrode cap 41 made of a nickel-plated steel plate formed in a cap shape and a bottom plate 42 made of a nickel-plated steel plate formed in a dish shape, which are welded. It is integrated.

  In this case, an exhaust port 42 a is formed at the center of the bottom plate 42, and a flange portion 42 b is formed at the outer periphery of the bottom plate 42. A pressure valve including a valve plate 43 and a spring 45 is disposed in a space formed by the positive electrode cap 41 and the bottom plate 42. A nickel-plated steel plate 44 is disposed between the valve plate 43 and the spring 45. The flange portion 42 b of the bottom plate 42 is sandwiched by an insulating gasket 46 made of polypropylene (PP), and this insulating gasket 46 is disposed on the throttle portion 47 a formed on the upper portion of the outer can 47. The upper portion 47b is caulked to be liquid-tight.

  However, when the PTC element 38 is built in the sealing body 30, as shown in FIG. 3, the flange portion 36 of the bottom plate 34, the insulating gasket 39, the PTC element 38, the flange portion 33 of the positive electrode cap 31, and the caulking portion of the bottom plate 34. A six-layer structure in which 36a is laminated is obtained. For this reason, the thickness of the outer peripheral part of the sealing body (the part caulked to the outer can through the insulating gasket) is increased. As a result, since the volume in which the electrode group is accommodated is reduced, there is a problem in that the battery capacity must be sacrificed when the sealing body incorporating the PTC element is used.

  Also, unlike lithium-based secondary batteries, alkaline storage batteries are equipped with non-destructive resettable gas discharge valves (pressure valves). Therefore, if functional parts such as PTC elements are placed inside the sealing body, they can be used in daily use. The PTC element may be deteriorated by the alkali mist that is finely discharged, and it has been difficult to integrate the PTC element and the sealing body. Further, when the return-type gas discharge valve (pressure valve) is disposed in the sealed body having the PTC element as described above, an exhaust port is formed at the center of the bottom plate, and a predetermined position above the exhaust port is formed. It is necessary to be able to arrange the pressure valve in the. However, when the sealing body is formed without the pressure valve being disposed at a predetermined position above the exhaust port, there arises a problem that the sealing performance is deteriorated.

  Therefore, the present invention was made to solve the above problems, and without reducing the volume in the outer can, the PTC element is provided in the sealing body in a form suitable for an alkaline storage battery, An object of the present invention is to provide a sealed storage battery in which a pressure valve (reset type gas discharge valve) is arranged at a predetermined position to prevent generation of a large current at the time of a short circuit and to improve safety.

  In order to achieve the above object, a sealing body used in a sealed storage battery according to the present invention includes a cap portion formed with a flange and a bottom plate for sealing an opening of an outer can, and the cap portion and the bottom plate. And form a valve chamber for accommodating the pressure valve. And the protrusion part for positioning the pressure valve which seals the exhaust port formed in the center part of the baseplate is integrally formed with this baseplate so that it may protrude toward a valve chamber from a baseplate. In this way, when the protrusion for positioning the pressure valve is formed, the pressure valve can be easily arranged at a predetermined position above the exhaust port. It becomes possible to improve the sealing performance of the battery.

  In this case, it is desirable that the protrusion is an annular protrusion that covers the periphery of the exhaust port in an annular shape because it is easy to position the pressure valve. In addition, if the projection for positioning the pressure valve is formed at a position facing the side wall of the cap part of the bottom plate, when the seal is manufactured, the pressure valve rides on the projection and is assembled. In addition, since the cap part is pushed up and the overall height of the sealing body is increased, it is possible to easily sort out assembly defects. Thereby, the reliability with respect to the sealing performance of this type of sealing body is improved. In addition, if the wall of the protrusion on the side where the pressure valve is arranged is formed so as to rise substantially vertically from the top surface of the bottom plate, the pressure valve can be easily placed at a predetermined position without riding on the protrusion. become able to. Further, it is desirable that the pressure valve is composed of an elastic valve and a spring for applying an urging force to the elastic valve because the pressure valve is simple and easy to manufacture.

  If a ring-shaped PTC (Positive Temperature Coefficient) element is arranged on the upper surface of the flange of the cap portion, the PTC element can be isolated outside the valve chamber. As a result, it is possible to prevent the electrolytic solution from adhering to the PTC element, so that the deterioration of the PTC element can be prevented beforehand. In addition, since the PTC element is disposed adjacent to the valve chamber, the temperature in the valve chamber can be monitored with high accuracy.

  Further, if the PTC element is caulked to the upper surface of the flange of the cap portion by the folded portion formed on the outer peripheral portion of the bottom plate, it is not necessary to arrange the PTC element on the outermost peripheral portion of the bottom plate. It is possible to reduce the thickness of the caulking portion when it is attached to the opening of the can. As a result, the volume inside the outer can is not reduced, and it is possible to attach a sealing body equipped with a PTC element, which prevents the generation of a large current at the time of a short circuit and improves the safety. A storage battery can be provided.

  An embodiment in which the present invention is applied to a nickel-hydrogen storage battery will be described below with reference to FIGS. FIG. 1 is a cross-sectional view schematically showing the main part of the nickel-hydrogen storage battery according to the present invention, and FIG. 1 (a) shows the main part in a state where the sealing body is attached to the opening of the outer can. FIG. 1B is a cross-sectional view illustrating a part of the portion A in FIG. FIG. 2 is an exploded sectional view showing parts of the sealing body of FIG.

1. Sealing body As shown in FIGS. 1 and 2, the sealing body 10 of the present invention includes a bottom plate 11 that seals the opening of the outer can 18 and a space portion (a positive terminal and a pressure valve accommodated therein). A positive electrode cap 12 that forms a valve chamber), an insulating ring 13 that electrically insulates between the bottom plate 11 and the positive electrode cap 12, an elastic valve 14 having a nickel-plated steel plate 14a on its upper surface, and the elastic valve 14 A spring 15 for applying an urging force and a PTC element ring 16 disposed on the flange 12a of the positive electrode cap 12 are configured. An insulating gasket 17 is attached to the outer periphery of the sealing body 10 so as to seal the opening of the outer can 18.

  The bottom plate 11 is formed in a dish shape from a nickel-plated steel plate, and an exhaust port 11a is formed in the center of the dish shape. An annular projection 11b for arranging the elastic valve 14 at a predetermined position is formed around the exhaust port 11a so as to protrude upward from the bottom plate 11. In this case, the annular protrusion 11b is formed at a position corresponding to the lower part of the side wall of the positive electrode cap 12, and the wall surface of the annular protrusion 11b on the side where the elastic valve 14 is disposed (exhaust port 11a side) , A rising surface 11c rising from the bottom plate 11 in a substantially vertical direction is formed. This makes it difficult for the elastic valve 14 to ride on the annular protrusion 11b, so that the elastic valve 14 can be easily disposed at a predetermined position above the exhaust port 11a.

  Here, the bottom plate 11 is formed substantially flat. This is because the bottom plate 35, 42 shown in FIGS. 3 and 4 has a concave shape at the center. In particular, in the bottom plate 42 shown in FIG. 4, the central recess houses the valve plate 43. Because it is a space, the internal volume of the battery decreases as the center is recessed. However, in the present invention, since the elastic valve 14 can be positioned by the annular protrusion 11b, the shape of the bottom plate 11 can be made flat. As a result, the internal volume of the battery can be increased only by that amount.

  The height of the annular protrusion 11b (the height from the upper surface of the bottom plate 11) is 0.3 mm. The rising surface 11c is formed so that the angle (θ) between the rising surface 11c formed on the wall surface of the annular protrusion 11b and the upper surface of the bottom plate 11 is 90 to 110 °. In addition, a locking recess 11d is formed in the lower portion of the bottom plate 11 corresponding to the annular projection 11b, which serves as a locking portion for a jig when the annular projection 11b is formed.

  Further, a DI processed portion (thin portion) 11e subjected to DI processing is formed on the outer peripheral portion from the dish-shaped end portion of the bottom plate 11 to the outermost end, and is half the thickness of the dish-shaped portion of the bottom plate 11 Thinned to be thick. A folded portion 11f is formed at about 1/3 of the thinned portion by DI processing, and a PTC element ring 16 to be described later is provided on the inner peripheral side of the folded portion 11f. A caulking portion 11g that is caulked to the upper surface of the flange 12a of the positive electrode cap 12 is formed.

  The positive electrode cap 12 is formed of a nickel-plated steel plate, the center portion swells in a cap shape, and a flange 12a is formed on the outer peripheral portion serving as the bottom side. The diameter of the flange 12a of the positive electrode cap 12 is formed to be slightly shorter than the dish-shaped end portion of the bottom plate 11. An exhaust port (not shown) is formed on the side wall of the positive electrode cap 12.

  The insulating ring 13 is formed in a ring shape from polypropylene (PP), has a diameter arranged between the dish-shaped end portions of the bottom plate 11, and has a positioning annular projection 11 b formed on the bottom plate 11. An opening having a diameter slightly larger than the outer diameter is formed. Further, a rising portion 13 a is formed on the peripheral edge of the end portion of the insulating ring 13. Thereby, even if the flange 12a formed on the outer periphery of the positive electrode cap 12 is disposed on the insulating ring 13, it is possible to prevent the flange portion 12 and the folded portion 11f formed on the bottom plate 11 from contacting each other. Become. As a result, when the PTC element ring 16 is later disposed on the flange portion 12 of the positive electrode cap 12, the positive electrode cap 12 passes through the folded portion 11f, the caulking portion 11g, the PTC element ring 16 and the flange 12a formed on the bottom plate 11. A discharge current starts to flow.

  The thickness of the insulating ring 13 is 0.4 mm so as to be higher than the height 0.3 mm of the annular protrusion 11b. This is because if the thickness of the insulating ring 13 is lower than the annular protrusion 11b, the tip of the annular protrusion 11b comes into contact with the positive electrode cap 12, and a circuit through which a current flows in the PTC element ring 16 as described later is formed. This is because the positive electrode cap 12 cannot be mounted horizontally with respect to the bottom plate 11. In this case, for example, by forming the inner peripheral side of the insulating ring 13 so as to approach the elastic valve 14, it is possible to make the annular protrusion 11b unnecessary by combining the role of the annular protrusion 11b.

However, if the insulating ring 13 is too close to the elastic valve 14, when the PTC element ring 16 trips and generates heat, the insulating ring 13 is softened or melted by the heat. As a result, it is conceivable that the resin of the insulating ring 13 sticks to the elastic valve 14 and hinders the valve operation. For this reason, the insulating ring 13 cannot be used as the annular protrusion 11b, and the annular protrusion 11b is provided and arranged on the outer peripheral side of the annular protrusion 11b.
Further, when the PTC element ring 16 trips and generates heat, the insulating ring 13 softens the insulating ring 13, so that the insulating ring 13 elastically receives the expansion stress caused by the heat generated by the PTC element ring 16. You can have it.

  The elastic valve 14 is made of ethylene propylene rubber (EPDM), and the elastic valve 14 is arranged so as to close the exhaust port 11 a formed in the dish-shaped center portion of the bottom plate 11. A nickel plated steel plate 14a is disposed on the upper surface of the elastic valve 14, and a spring 15 for applying a biasing force to the nickel plated steel plate 14a is disposed on the nickel plated steel plate 14a. As a result, when the inside of the battery is pressurized to a predetermined pressure or higher, the elastic valve 14 is pushed up against the urging force of the spring 15 and the gas is discharged from the exhaust port (not shown) of the positive electrode cap 12. The pressure in the battery is reduced.

  The PTC element ring 16 is a PTC (Positive Temperature Coefficient) element made of a conductive polymer material having a positive temperature characteristic, and has a product name “Polyswitch” (manufactured by Raychem) whose resistance value increases as the temperature rises. It is a commercially available device, has a cut-off current characteristic of 3 A or less at room temperature, 1 A or less at 60 ° C., and a withstand voltage characteristic that can withstand 1000 times or more of charge and discharge with a current of 5 A applied at a voltage of 15 V. The minute leakage current that flows after the current interruption is 0.5 A or less.

  The inner peripheral wall surface of the PTC element ring 16 is covered with an olefin resin film to prevent deterioration due to adhesion of alkali mist or the like. In this case, an olefin is formed in the gap between the inner peripheral wall surface of the PTC element ring 16 and the outer peripheral surface of the side wall of the positive electrode cap 12, and the gap between the end portion of the caulking portion 11 g of the bottom plate 11 and the outer peripheral surface of the side wall of the positive electrode cap 12. You may make it fill with resin. In this way, if these gaps are closed with an olefin resin, current does not flow to the PTC element ring 16 when a conductive foreign matter or the like is caught in these gaps (bypassing the PTC element ring 16). Forming a circuit to be performed) can be prevented in advance.

  An opening having a diameter slightly larger than the diameter of the bulging portion of the positive electrode cap 12 is formed at the center of the PTC element ring 16, and is disposed on the upper surface of the flange 12 a of the positive electrode cap 12. As a result, a discharge current flows to the positive electrode cap 12 through the folded portion 11f, the caulking portion 11g, the PTC element ring 16 and the flange 12a formed on the bottom plate 11. The operating region of the PTC element ring 16 is set to 3 A or less at normal temperature (25 ° C.) and 1 A at high temperature (60 ° C.).

2. Next, a method for assembling the sealing body 10 configured as described above will be described below. First, a bottom plate 11 is prepared in which an exhaust port 11a is formed in a dish-shaped central portion, and an annular protrusion 11b for arranging an elastic valve 14 is formed at a predetermined position above the exhaust port 11a. Next, DI processing is performed on the outer peripheral side from the dish-shaped end portion of the bottom plate 11 toward the outermost end, so that the thickness is reduced to half the thickness of the dish-shaped portion of the bottom plate 11. Part (thin wall part) 11e was formed. Thereafter, the DI processed portion 11e was bent into an L shape so that the sealing body 10 had a predetermined diameter, thereby forming a bent portion (see the dotted line in FIG. 2).

  Next, after the insulating ring 13 having the rising portion 13a formed on the peripheral edge of the end plate is disposed in the dish-shaped portion of the bottom plate 11, the elastic valve 14 is closed so as to close the exhaust port 11a formed in the dish-shaped center portion of the bottom plate 11. Arranged. Next, after the spring 15 was disposed on the nickel-plated steel plate 14 a disposed on the upper surface of the elastic valve 14, the flange 12 a of the positive electrode cap 12 was disposed on the insulating ring 13. Subsequently, the PTC element ring 16 was disposed on the flange 12a, and the folded portion 11f was formed by folding the folded portion of the bottom plate 11 inward.

  Thereafter, a crimped portion 11g is formed by caulking the tip of the DI processed portion (thin portion) 11e toward the flange 12a side of the positive electrode cap 12, and the PTC element ring 16 is fixed to the upper surface of the flange 12a of the positive electrode cap 12. did. As a result, the elastic valve 14 is given a biasing force by the spring 15, the exhaust port 11 a is closed by the elastic valve 14, and the sealing body 10 is formed.

3. Nickel-hydrogen storage battery Next, an example of manufacturing a nickel-hydrogen storage battery using the sealing body 10 manufactured as described above will be described below. First, a nickel sintered porous body is formed on the surface of an electrode plate core made of punching metal, and then the nickel sintered porous body is filled with an active material mainly composed of nickel hydroxide by a chemical impregnation method. Produced. On the other hand, the surface of an electrode plate core made of foamed nickel was filled with a paste-like negative electrode active material made of a hydrogen storage alloy, dried, and then rolled to a predetermined thickness to produce a hydrogen storage alloy negative electrode plate.

  A spiral electrode group was fabricated by winding a separator between the nickel positive electrode plate and the hydrogen storage alloy negative electrode plate in a spiral shape. The end of the electrode plate core of the nickel positive electrode plate is exposed at the upper end surface of the spiral electrode group, and the end of the electrode plate core of the hydrogen storage alloy negative electrode plate is exposed at the lower end surface. . The core exposed at the upper end surface of the spiral electrode group and the positive electrode current collector were welded, and the core exposed at the lower end surface and the negative electrode current collector were welded. A positive electrode lead is provided to extend from the end of the positive electrode current collector, and the end of the positive electrode lead is welded to the lower end surface of the sealing body after an insulating gasket is fitted.

  Next, after the spiral electrode group is housed in a bottomed cylindrical outer can 18 in which nickel is plated on iron (the outer surface of the bottom surface becomes a negative electrode external terminal) 18, the negative electrode current collector is placed on the inner bottom surface of the outer can 18. Spot welded. Thereafter, the upper outer peripheral surface of the outer can 18 is grooved 18a, the positive lead extending from the positive current collector is bent vertically, and the end of the positive lead is connected to the bottom plate 11 of the sealing body 10. Resistance welded. Next, an alkaline electrolyte made of a 30% by mass potassium hydroxide (KOH) aqueous solution was injected into the outer can 18.

  Next, an insulating gasket 17 made of polypropylene (PP) was attached to the folded portion 11f of the bottom plate 11 serving as the flange portion of the sealing body 10, and then the positive electrode lead was bent to place the sealing body 10 in the opening of the outer can. Thereafter, the opening edge 18b of the outer can 18 was caulked inward to seal the opening and sealed. Thereby, a nickel-hydrogen storage battery having a nominal capacity of 1.7 Ah was produced.

  In the above-described embodiment, an example in which the present invention is applied to a nickel-hydrogen storage battery has been described. However, the present invention is not limited to a nickel-hydrogen storage battery, and other sealed devices such as a nickel-cadmium storage battery and a lithium ion battery. It is clear that the present invention can be applied to a storage battery of a shape.

It is sectional drawing which shows typically the principal part of the sealed storage battery of this invention, FIG.1 (a) is sectional drawing which shows the principal part in the state which mounted | wore the opening of the exterior can, and FIG. FIG. 2B is an enlarged cross-sectional view illustrating a part of the portion A in FIG. It is sectional drawing which decomposes | disassembles and shows the components of the sealing body of FIG. It is sectional drawing which shows the sealing body provided with the PTC element of the prior art example. It is sectional drawing which shows the sealing body which is not provided with the PTC element of a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Sealing body, 11 ... Bottom plate, 11a ... Exhaust port, 11b ... Annular projection part, 11c ... Rising surface of an annular projection part, 11d ... Concave part for latching, 11e ... DI process part (thin wall part), 11f ... Folding part , 11g ... crimping part, 12 ... positive electrode cap, 12a ... flange, 13 ... insulating ring, 13a ... rising part, 14 ... elastic valve, 14a ... nickel plated steel plate, 15 ... spring, 16 ... PTC element ring, 17 ... insulating gasket , 18 ... Exterior can

Claims (6)

An electrode group in which a positive electrode and a negative electrode are wound through a separator, an outer can having an opening that accommodates the electrode group and also serves as a terminal of one electrode, and an opening of the outer can through an insulating gasket A sealed storage battery having a sealing body that also serves as a terminal of the other electrode to be sealed and has a built-in pressure valve,
The sealing body includes a cap portion formed with a flange, and a bottom plate that seals the opening, and forms a valve chamber that houses the pressure valve with the cap portion and the bottom plate.
A protrusion for positioning the pressure valve sealing the exhaust port formed at the center of the bottom plate is formed integrally with the bottom plate so as to protrude from the bottom plate toward the valve chamber. A sealed storage battery characterized by.   The sealed storage battery according to claim 1, wherein the protrusion is an annular protrusion that annularly covers the periphery of the exhaust port.   3. The sealed storage battery according to claim 1, wherein the protruding portion is formed at a position facing the side wall of the cap portion of the bottom plate.   4. The hermetically sealed type according to claim 1, wherein a wall surface of the protrusion on the side where the pressure valve is disposed is formed so as to rise substantially vertically from an upper surface of the bottom plate. Storage battery.   5. The sealed storage battery according to claim 1, wherein the pressure valve includes an elastic valve and a spring that applies a biasing force to the elastic valve. A ring-shaped PTC (Positive Temperature Coefficient) element is disposed on an upper surface of the flange of the cap part, and the PTC element is fixed by a folded part formed on an outer peripheral part of the bottom plate. The sealed storage battery according to any one of claims 1 to 5.

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