A sealing body for cylindrical storage batteries, and a cylindrical storage battery using the sealing body.

Abstract

A sealing body (11) of the present invention comprises a first cover plate (11a) fixed to a cylindrical storage battery (2), a second cover plate (11b) that forms a containment space (S) between itself and the first cover plate, and an elastic valving element (11c) which is disposed inside the containment space and compressed between the first and second cover plates. The first cover plate includes an annular, hollow disk-shaped base portion (11e) around an axis line x, an annular first sidewall portion (11g) extending downward from the base portion, and a bottom wall portion (11i) connected to the first sidewall portion. The first sidewall portion has first through-holes (11l) that pass through the first sidewall portion in a direction approaching the axis line. The second cover plate has communicating holes (11d) joining the containment space with an external space. The valving element is disposed between the first through-holes and the communicating holes in the direction of fluid flow.

Description

Technical Field

[0001] The present invention relates to a sealing body for a cylindrical battery and a cylindrical battery using the sealing body.

Background Art

[0002] Conventionally, a secondary battery provided with a safety valve for discharging gas filled in the battery when the internal pressure of the battery rises due to overcharging is known. For example, the secondary battery described in Patent Document 1 accommodates a power generation element in a battery case formed in a bottomed cylindrical shape, and fixes a sealing plate to the opening end side of the battery case by caulking through an outer gasket, so that the opening end of the battery case is sealed.

[0003] In the secondary battery described in Patent Document 1, the sealing plate is configured by arranging a sealing bottom plate, a lower metal thin plate, an upper metal thin plate, a PTC element, a substrate support plate, and a circuit board in this order from the inside of the battery. The lower metal thin plate and the upper metal thin plate have a function as a discharge valve for gas generated in the battery. That is, when the internal pressure of the battery abnormally rises due to gas generated by decomposition of the electrolytic solution accompanying abnormal use, the internal pressure of the battery reaches the lower metal thin plate from the opening formed in the sealing bottom plate, and the lower metal thin plate and the upper metal thin plate are deformed to the outside of the battery. Then, when the lower metal thin plate and the upper metal thin plate break, there is no longer anything to shield between the inside of the battery and the inside of the sealing plate, so the gas is discharged to the outside through the discharge holes formed in the substrate support plate.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Incidentally, in recent years, the demand for nickel-metal hydride batteries has been increasing due to reasons such as their high capacity and cleanliness. To achieve high capacity in nickel-metal hydride batteries, the number of turns in the spiral electrode group is sometimes increased to increase the surface area between the positive and negative electrodes. However, increasing the number of turns in the spiral electrode group makes it easier for the negative and positive electrodes to come into direct contact, and the resulting abnormal heat generation can cause the contents of the battery case (e.g., separators) to melt. These melted contents are usually released to the outside along with the gas.

[0006] However, in the secondary battery described in Patent Document 1, the opening is formed in the sealing bottom plate facing vertically (parallel to the battery axis), so there was a risk that a large amount of molten contents could flow into the opening and cause it to become blocked. In particular, since there is more contents (e.g., excess separator) in the inner circumference region of the vortex electrode group, a particularly large amount of contents could flow into the opening formed in the center of the sealing bottom plate, potentially causing it to become blocked. If the opening is blocked by molten contents in this way, the gas filled by the charge-discharge cycle cannot be released, and consequently the increased internal pressure cannot be reduced, which could lead to the battery rupturing or other problems.

[0007] The present invention has been made in view of these problems, and its objective is to provide a sealing body for a cylindrical storage battery that suppresses blockage by the contents of the battery and improves the safety of the battery, and a cylindrical storage battery using the sealing body. [Means for solving the problem]

[0008] To achieve the above objective, the sealing body is a sealing body for a cylindrical storage battery, comprising: a first cover plate fixed to the cylindrical storage battery; a second cover plate fixed to the upper surface of the first cover plate and forming a housing space between itself and the first cover plate; and an elastic valve body compressed between the first cover plate and the second cover plate and disposed inside the housing space, wherein the first cover plate comprises a hollow disc-shaped base portion formed annularly around the axis of the cylindrical storage battery, and extending downward from the inner peripheral edge of the base portion, The valve comprises a first side wall portion formed in an annular shape around an axis and a bottom wall portion connected to the lower edge of the first side wall portion, wherein the first side wall portion includes at least one first through hole penetrating between the outer and inner circumferential surfaces of the first side wall portion in a direction toward the axis, the second cover plate includes a communication hole in at least a part of the second cover plate that connects the housing space and the external space, and the valve body is disposed between the first through hole and the communication hole in the direction of fluid flow.

[0009] In a sealing body according to one aspect of the present invention, the first through hole is formed perpendicular to the axis.

[0010] In a sealing body according to one aspect of the present invention, the bottom wall portion is formed in the shape of a hollow disc formed annularly around the axis, the first cover plate includes a second side wall portion extending upward from the inner circumferential edge of the bottom wall portion and formed annularly around the axis, and a top wall portion connected to the upper edge of the second side wall portion, the second side wall portion includes at least one second through hole penetrating between the outer circumferential surface and the inner circumferential surface of the second side wall portion in a direction toward the axis, and the valve body is disposed between the second through hole and the communication hole in the direction of fluid flow.

[0011] In a sealing body according to one aspect of the present invention, the second through hole is formed perpendicular to the axis.

[0012] Furthermore, the cylindrical storage battery according to the present invention is characterized by comprising: a spiral electrode group formed by overlapping a strip-shaped positive electrode plate, a strip-shaped negative electrode plate, and a strip-shaped separator disposed between the positive electrode plate and the negative electrode plate; a conductive outer casing having a closed cylindrical shape with an opening on one side, which houses the spiral electrode group together with an electrolyte; a positive electrode terminal electrically connected to the positive electrode plate; and a sealing body fixed to the outer casing so as to close the opening of the outer casing. [Effects of the Invention]

[0013] According to the sealing body and cylindrical storage battery of the present invention, the first side wall portion includes at least one first through-hole that penetrates between the outer and inner circumferential surfaces of the first side wall portion in a direction toward the axis, the second cover plate includes a communication hole in at least a part of the second cover plate that connects the housing space and the external space, and the valve body is disposed between the first through-hole and the communication hole in the direction of fluid flow. Thus, the first through-hole of the sealing body is provided at a position away from the axis of the cylindrical storage battery, that is, at a position away from the central region of the cylindrical storage battery, and is formed in a direction toward the axis, that is, non-parallel to the axis. For this reason, even if the contents of the swirl electrode group (e.g., separator, etc.) melt due to abnormal heat generation caused by a short circuit in the storage battery, it is possible to avoid the first through-hole being blocked by the contents. In particular, the first through-hole is positioned away from the inner circumferential region of the spiral electrode group, where molten contents tend to concentrate. Therefore, even if the contents melt in the inner circumferential region of the spiral electrode group where more contents (e.g., excess separator) are present, the first through-hole can be prevented from being blocked by the contents. As a result, even if abnormal heat generation occurs due to a short circuit, the molten contents can be discharged to the outside space through the first through-hole, the containment space, and the communication hole, and consequently, the gas inside the battery can be discharged to the outside space. Thus, incidents such as battery rupture can be avoided, and the safety of the battery can be improved. [Brief explanation of the drawing]

[0014] [Figure 1] This is a cross-sectional view of a sealing body for a cylindrical storage battery according to one embodiment. [Figure 2] Figure 1 is a bottom view of the sealing body, seen from below. [Figure 3] Figure 1 is a side view of the sealing body as seen from the direction of arrow A. [Figure 4] Figure 1 is a cross-sectional view of a cylindrical storage battery with the sealing body attached. [Modes for carrying out the invention]

[0015] The following describes an embodiment of a sealing body 11 for a nickel-metal hydride secondary battery 2 (hereinafter also simply referred to as "battery 2") as a sealing body for a cylindrical storage battery according to one embodiment, and an embodiment of the battery 2 to which the sealing body 11 is attached. In this embodiment, an AA-sized cylindrical battery 2 is described, but the size of battery 2 is not limited to this, and other sizes such as AAA size may also be used. Furthermore, the cylindrical storage battery may be any battery that uses an alkaline solution as the electrolyte, such as a nickel-cadmium storage battery.

[0016] Figure 1 is a cross-sectional view of a sealing body 11 for a nickel-metal hydride secondary battery 2 (cylindrical storage battery) according to one embodiment. Figure 2 is a bottom view of the sealing body 11 of Figure 1, viewed from below. Figure 3 is a side view of the sealing body 11 of Figure 1, viewed from direction A. Figure 4 is a cross-sectional view of the battery 2 to which the sealing body 11 of Figure 1 is attached. For the sake of explanation, as shown in Figure 4, along the axis x of the cylindrical outer casing 10, the direction of arrow a is considered the upper side and the direction of arrow b is considered the lower side. Here, the upper side means the side of the battery 2 to which the sealing body 11 is provided, and the lower side means the side of the battery 2 to which the bottom wall 35 is provided, which is the opposite side of the upper side. Also, in the direction perpendicular to the axis x (hereinafter also referred to as the "radial direction"), the direction away from the axis x is considered the outer circumference (direction of arrow c), and the direction toward the axis x is considered the inner circumference (direction of arrow d).

[0017] As shown in FIG. 4, the battery 2 includes an outer can 10 having a bottomed cylindrical shape with an upper side (in the direction of arrow a) open. The outer can 10 of the battery 2 has an annular cylindrical shape around an axis x extending in the vertical direction. The outer can 10 has conductivity, and a bottom wall 35 provided on the lower side (in the direction of arrow b) functions as a negative electrode terminal. A sealing body 11 is fixed to the opening of the outer can 10, and the sealing body 11 is used to seal the outer can 10 of the battery 2.

[0018] As shown in FIGS. 1 to 3, the sealing body 11 includes a first cover plate 11a, a second cover plate 11b, and an elastic valve body 11c.

[0019] The first cover plate 11a is a conductive member integrally formed including a base portion 11e, a first side wall portion 11g, and a bottom wall portion 11i, and is configured with the same or substantially the same plate thickness as a whole. The base portion 11e of the first cover plate 11a is a hollow disk-shaped portion formed in an annular shape around the axis x of the battery 2. The first cover plate 11a includes a fixed portion 11v which is a plate-shaped portion extending further in the outer peripheral direction from the outer peripheral side end portion of the base portion 11e. The fixed portion 11v is formed in an annular shape around the axis x.

[0020] The first side wall portion 11g of the first cover plate 11a extends downward from the inner peripheral side edge portion 11f of the base portion 11e and is formed in an annular shape around the axis x. The first side wall portion 11g includes at least one first through hole 11l penetrating in the direction toward the axis x between the outer peripheral side surface 11j and the inner peripheral side surface 11k of the first side wall portion 11g. Specifically, the first through hole 11l is formed in a direction perpendicular to the axis x. Also, as shown in FIG. 2, four first through holes 11l are formed in the first side wall portion 11g at equal intervals (90° intervals).

[0021] The bottom wall portion 11i of the first cover plate 11a is connected to the lower edge portion 11h of the first side wall portion 11g. The bottom wall portion 11i is formed in a hollow disk shape that is annularly formed around the axis x. And the first cover plate 11a includes a second side wall portion 11n that extends upward from the inner peripheral edge portion 11m of the bottom wall portion 11i and is annularly formed around the axis x, and a ceiling wall portion 11p that is connected to the upper edge portion 11o of the second side wall portion 11n.

[0022] As shown in FIGS. 1 to 3, the second side wall portion 11n includes at least one second through hole 11s that penetrates in the direction of the axis x between the outer peripheral side surface 11q and the inner peripheral side surface 11r of the second side wall portion 11n. Specifically, the second through hole 11s is formed in a direction perpendicular to the axis x. Also, as shown in FIG. 2, four second through holes 11s are formed in the second side wall portion 11n at equal intervals (90° intervals). Each of the second through holes 11s is arranged in alignment with each of the first through holes 11l in the radial direction.

[0023] As shown in FIG. 1, the second cover plate 11b is a conductive member integrally formed including a hollow disk-shaped flange portion which is annularly formed around the axis x of the battery 2, a connection portion 11u that extends upward from the inner peripheral edge portion of the flange portion 11w and is annularly formed around the axis x, and a pressing portion 11t that is connected to the upper edge portion of the connection portion 11u, and is configured with the same or substantially the same plate thickness as a whole.

[0024] The second cover plate 11b is fixed to the upper surface of the base portion 11e of the first cover plate 11a at the flange portion 11w, forming a housing space S between it and the first cover plate 11a. The second cover plate 11b is a metal member and is electrically connected to the metal first cover plate 11a. The second cover plate 11b includes a communication hole 11d in at least a portion of the second cover plate 11b that connects the housing space S to the external space. Specifically, the communication hole 11d is formed penetrating the connection portion 11u of the second cover plate 11b between its outer and inner circumferential surfaces in a direction toward the axis x. More specifically, the communication hole 11d is formed perpendicular to the axis x. Furthermore, four communication holes 11d are formed in the connection portion 11u at equal intervals (90° intervals).

[0025] As shown in Figure 1, the valve body 11c is made of rubber and is compressed between the first cover plate 11a and the second cover plate 11b, and is disposed inside the containment space S. Specifically, the valve body 11c is positioned in contact with the upper surface of the base portion 11e and the upper surface of the ceiling wall portion 11p, and is pressed against the base portion 11e and the ceiling wall portion 11p by the pressing portion 11t of the second cover plate 11b. As shown in Figures 1 and 4, the valve body 11c is disposed between the first through hole 11l and the communication hole 11d in the direction of fluid flow. Alternatively, the valve body 11c may be disposed between the second through hole 11s and the communication hole 11d in the direction of fluid flow. The direction of fluid flow refers to the direction from the inside of the outer casing 10 toward the external space of the battery 2, and means the direction of flow of the molten contents and gas.

[0026] As shown in Figure 4, a first lid plate 11a and a ring-shaped insulating packing 12 surrounding the first lid plate 11a are arranged inside the opening of the outer can 10. The insulating packing 12 is fixed to the opening edge 37 of the outer can 10 by crimping the edge 37 of the outer can 10. In other words, the first lid plate 11a and the insulating packing 12 work together to airtightly close the opening of the outer can 10.

[0027] Under normal conditions, the first through-hole 11l and the second through-hole 11s are airtightly closed by the valve body 11c, blocking communication with the communication hole 11d of the second cover plate 11b. However, if gas is generated inside the outer casing 10 and the pressure of the gas increases, the valve body 11c is compressed upward by the gas pressure, opening the first through-hole 11l and the second through-hole 11s. As a result, gas is released from inside the outer casing 10 to the outside through the first through-hole 11l, the second through-hole 11s, and the communication hole 11d of the second cover plate 11b. In other words, the first through-hole 11l, the second through-hole 11s, the communication hole 11d of the second cover plate 11b, and the valve body 11c form a safety valve for the battery 2.

[0028] As shown in Figure 4, the outer casing 10 houses a spiral electrode group 22. This spiral electrode group 22 is formed by overlapping strip-shaped positive electrode plates 24, negative electrode plates 26, and separators 28. The spiral electrode group 22 is formed in a spiral shape with the separator 28 sandwiched between the positive electrode plate 24 and the negative electrode plate 26. In other words, the positive electrode plate 24 and the negative electrode plate 26 are overlapped via the separator 28.

[0029] Inside the outer can 10, a positive electrode lead 30 is positioned between the upper end of the spiral electrode group 22 and the first cover plate 11a. Specifically, one end of the positive electrode lead 30 is connected to the positive electrode plate 24, and the other end is connected to the first cover plate 11a. Therefore, the second cover plate 11b and the positive electrode plate 24 are electrically connected to each other via the positive electrode lead 30 and the first cover plate 11a. A circular upper insulating member 32 is positioned between the first cover plate 11a and the spiral electrode group 22, and the positive electrode lead 30 extends through a slit 39 provided in the upper insulating member 32. A circular lower insulating member 34 is also positioned between the spiral electrode group 22 and the bottom wall 35 of the outer can 10.

[0030] Furthermore, a predetermined amount of alkaline electrolyte (not shown) is injected into the outer can 10. This alkaline electrolyte impregnates the vortex electrode group 22 and promotes the electrochemical reaction (charge-discharge reaction) during charging and discharging between the positive electrode plate 24 and the negative electrode plate 26. It is preferable to use an aqueous solution containing at least one of KOH, NaOH, and LiOH as a solute for this alkaline electrolyte.

[0031] For example, the material used for the separator 28 may be a nonwoven fabric made of polyamide fibers to which hydrophilic functional groups have been added, or a nonwoven fabric made of polyolefin fibers such as polyethylene or polypropylene to which hydrophilic functional groups have been added.

[0032] The positive electrode plate 24 comprises a conductive positive electrode substrate having a porous structure and a positive electrode mixture held within the pores of the positive electrode substrate. For example, a sheet of foamed nickel can be used as such a positive electrode substrate. The positive electrode mixture comprises positive electrode active material particles and a binder. Positive electrode additives may also be added to the positive electrode mixture as needed.

[0033] The negative electrode plate 26 comprises a metal negative electrode core and a negative electrode mixture layer containing a negative electrode active substance supported on the negative electrode core, and is overall in the shape of a strip. The negative electrode core is conductive. The negative electrode mixture layer is formed on both sides of the negative electrode core. The negative electrode mixture layer is formed of a negative electrode mixture containing a negative electrode active substance. The negative electrode mixture is not only filled into the through-holes of the negative electrode core, but is also supported in layers on both sides of the negative electrode core to form a negative electrode mixture layer. The negative electrode mixture includes hydrogen-absorbing alloy particles capable of absorbing and releasing hydrogen as a negative electrode active material, a conductive agent, a binder, and a negative electrode auxiliary agent.

[0034] The positive electrode plate 24 and the negative electrode plate 26 are wound in a spiral shape with a separator 28 in between to form a spiral electrode group 22. The spiral electrode group 22 thus obtained is housed in an outer casing 10. Subsequently, a predetermined amount of alkaline electrolyte is injected into the outer casing 10. After that, the outer casing 10 containing the spiral electrode group 22 and the alkaline electrolyte is sealed with a sealing body 11 equipped with a first lid plate 11a, and a battery 2 according to one embodiment is obtained. The battery 2 is subjected to an initial activation treatment and made ready for use.

[0035] Next, the operation and effects of the sealing body 11 and battery 2 according to one embodiment will be described. As described above, according to the sealing body 11 and battery 2 according to one embodiment, the first side wall portion 11g includes at least one first through hole 11l that penetrates between the outer peripheral surface 11j and the inner peripheral surface 11k of the first side wall portion 11g in the direction toward the axis x, the second cover plate 11b includes a communication hole 11d in at least a part of the second cover plate 11b that connects the housing space S and the external space, and the valve body 11c is disposed between the first through hole 11l and the communication hole 11d in the direction of fluid flow. Thus, the first through hole 11l of the sealing body 11 is provided at a position away from the axis x of the battery 2, that is, at a position away from the central region of the battery 2, and is formed in the direction toward the axis x, that is, non-parallel to the axis x. Therefore, even if the contents of the spiral electrode group 22 (e.g., separator 28) melt due to abnormal heat generation caused by a short circuit within the battery 2, it is possible to avoid the first through-hole 11l being blocked by the melted contents. In particular, since the first through-hole 11l is located away from the inner circumferential region of the spiral electrode group where melted contents tend to concentrate, it is possible to avoid the first through-hole 11l being blocked by the melted contents even if the contents melt in the inner circumferential region of the spiral electrode group 22 where more contents (e.g., excess separator 28) are present. Therefore, even if abnormal heat generation occurs due to a short circuit, the melted contents can be discharged to the outside space through the first through-hole 11l, the containment space S, and the communication hole 11d, and consequently, the gas inside the battery 2 can be discharged to the outside space. Thus, it is possible to avoid situations such as the battery 2 rupturing, and the safety of the battery 2 can be improved.

[0036] Furthermore, according to the sealing body 11 and battery 2 of one embodiment, the first through-hole 11l is formed perpendicular to the axis x. Thus, the first through-hole 11l does not open in the direction in which the swirl electrode group 22 is arranged within the battery 2, i.e., downward (arrow b direction). Therefore, it is possible to avoid a situation in which a large amount of molten contents flows into the first through-hole 11l, and to avoid a situation in which the first through-hole 11l is blocked by the contents. Therefore, even if abnormal heat generation occurs due to a short circuit, the molten contents can be discharged to the outside space through the first through-hole 11l, the containment space S, and the communication hole 11d, and consequently, the gas inside the battery 2 can be discharged to the outside space.

[0037] Furthermore, according to the sealing body 11 and battery 2 according to one embodiment, the second side wall portion 11n includes at least one second through-hole 11s that penetrates between the outer peripheral surface 11q and the inner peripheral surface 11r of the second side wall portion 11n in a direction toward the axis x. The valve body 11c is disposed between the second through-hole 11s and the communication hole 11d in the direction of fluid flow. Thus, the second through-hole 11s of the sealing body 11 is provided at a position away from the axis x of the battery 2, that is, away from the central region of the battery 2, and is formed in a direction toward the axis x, that is, non-parallel to the axis x. Therefore, even if the contents of the swirl electrode group 22 (e.g., separator 28, etc.) melt due to abnormal heat generation caused by a short circuit in the battery 2, it is possible to avoid the second through-hole 11s being blocked by the contents. Furthermore, since the sealing body 11 has a second through-hole 11s in addition to the first through-hole 11l, even if the contents melt in the inner circumferential region of the vortex electrode group 22 where more contents (e.g., excess separator 28) are present, the contents can be dispersed into both the first through-hole 11l and the second through-hole 11s and discharged into the outside space. Therefore, even if abnormal heat generation occurs due to a short circuit, the melted contents can be discharged into the outside space through the first through-hole 11l, the second through-hole 11s, the containment space S, and the communication hole 11d, and consequently, the gas inside the battery 2 can be discharged into the outside space.

[0038] Furthermore, according to the sealing body 11 and battery 2 of one embodiment, the second through-hole 11s is formed perpendicular to the axis x. Thus, the second through-hole 11s does not open in the direction in which the swirl electrode group 22 inside the battery 2 is arranged, i.e., downward (arrow b direction). Therefore, it is possible to avoid a situation in which a large amount of molten contents flow into the second through-hole 11s, and to avoid a situation in which the second through-hole 11s is blocked by the contents. Therefore, even if abnormal heat generation occurs due to a short circuit, the molten contents can be discharged to the outside space through the second through-hole 11s, the containment space S, and the communication hole 11d, and consequently, the gas inside the battery 2 can be discharged to the outside space.

[0039] [Examples] To evaluate the performance of battery 2 according to one embodiment, a cylindrical storage battery with a height of 50 mm and an outer diameter of 14 mm was manufactured. In this embodiment, a sealing body 11 (having four first through holes 11l and four second through holes 11s) as shown in Figures 1 to 3 was prepared, and battery 2 as shown in Figure 4 was manufactured with this sealing body 11 attached. In contrast, as a comparative example, a sealing body was prepared with only one hole formed in the center of the base portion that penetrates the base portion vertically, and a battery was manufactured with this sealing body attached. Therefore, in the comparative example battery, only through holes parallel to the axis x are formed, and no holes penetrating in the direction toward the axis x are formed, as in the sealing body 11 of this embodiment. The comparative example battery is identical in configuration to battery 2 of this embodiment except for the configuration of the sealing body. Ten cells each of battery 2 of this embodiment and battery of the comparative example were manufactured, and a burner test was performed to attempt to reproduce the state in which heat was generated inside the battery. The burner test is a test specified in the UL standard (UL2054:2004 Clause 22), so a detailed explanation of its method will be omitted. As a result, in battery 2 according to this embodiment, there were zero cases of rupture and zero cases of deformation. Therefore, it was confirmed that in battery 2 of this embodiment, even when heat was generated inside the battery, the molten contents were discharged into the outside space, and consequently, the gas inside battery 2 was also discharged into the outside space. In contrast, in the battery according to the comparative example, there were zero cases of rupture, but deformation was found in 4 out of 10 cells. Therefore, it was confirmed that in the battery according to the comparative example, when heat was generated inside the battery, the gas inside the battery was not properly discharged into the outside space.

[0040] Although preferred embodiments of the present invention have been described above, the present invention is not limited to the sealing body 11 and nickel-metal hydride secondary battery 2 according to the above embodiments, but includes all aspects included in the concept and claims of the present invention, and each component may be selectively combined as appropriate. Furthermore, the shape, material, arrangement, size, etc. of each component in the above embodiments may be appropriately changed depending on the specific embodiment of the present invention.

[0041] For example, in the above embodiment, a configuration was described in which the bottom wall portion 11i of the first lid plate 11a is formed in the shape of a hollow circular disc. However, the bottom wall portion 11i may be formed without, for example, a through hole penetrating in the vertical direction. In this case, the first lid plate 11a does not have a second side wall portion 11n and a top wall portion 11p, and is generally formed in the shape of a cup that is recessed downwards.

[0042] Furthermore, in the above embodiment, an embodiment was described in which the first through hole 11l, the second through hole 11s, and the communication hole 11d are formed perpendicular to the axis x. However, the first through hole 11l, the second through hole 11s, and the communication hole 11d may be formed at an angle to the axis x, for example. Also, in the above embodiment, an embodiment was described in which four first through holes 11l, two through holes 11s, and communication holes 11d are formed at equal angles (90°) in the first side wall portion 11g, the second side wall portion 11n, and the connecting portion 11u, respectively. However, the number and position of the first side wall portion 11g, the second side wall portion 11n, and the connecting portion 11u are not limited thereto and may be changed as appropriate.

[0043] Furthermore, in the above embodiment, an arrangement was described in which each of the second through holes 11s is aligned with each of the first through holes 11l in the radial direction. However, the positional relationship between the second through holes 11s and the first through holes 11l is not limited to this, and for example, the second through holes 11s and the first through holes 11l may be formed offset from each other in the radial direction.

[0044] Furthermore, in the above embodiment, the valve body 11c is described as being made of rubber and being compressed and disposed in the housing space S. However, the form of the valve body 11c is not limited to this, and for example, a compression spring may be attached to the second cover plate 11b, and an iron plate and a rubber plate may be attached to the tip of the compression spring. Since such a valve body configuration is well known, a detailed explanation will be omitted. [Explanation of Symbols]

[0045] 2. Nickel-metal hydride rechargeable battery (cylindrical storage battery) 10 outer cans 11 Sealing body 11a 1st cover plate 11b 2nd cover plate 11c valve body 11d Communication hole 11e Base 11f Inner edge of the base 11g 1st side wall part 11h Lower edge of the first side wall 11i Bottom wall 11j Outer peripheral side of the first side wall 11k Inner circumferential surface of the first side wall 11l 1st through hole 11m Inner periphery edge of the bottom wall 11n 2nd side wall part 11o Upper edge of the second side wall 11p Ceiling and wall section 11q Outer peripheral side of the second side wall 11r Inner circumferential surface of the second side wall 11s 2nd through hole 22 Spiral electrode group 24 Positive plate 26 Negative plate 28 Separator a. Upper side b Lower side c Outer side d Inner side S Containment space x-axis

Claims

1. A sealing body for cylindrical storage batteries, A first cover plate fixed to the cylindrical storage battery, A second cover plate is fixed to the upper surface of the first cover plate and forms a storage space between itself and the first cover plate, It comprises an elastic valve body that is compressed between the first cover plate and the second cover plate and disposed inside the containment space, The first cover plate includes a flat base portion formed annularly around the axis of the cylindrical storage battery and in close contact with the end of the second cover plate; a first side wall portion extending downward from the inner circumferential edge of the base portion and formed annularly around the axis; a flat bottom wall portion connected to the lower edge of the first side wall portion and extending inward from the lower edge and formed annularly around the axis; a second side wall portion extending upward from the inner circumferential edge of the bottom wall portion and formed annularly around the axis; and a top wall portion connected to the upper edge of the second side wall portion. The first side wall portion includes at least one first through hole that penetrates between the outer and inner circumferential surfaces of the first side wall portion in a direction toward the axis, The second side wall portion includes at least one second through-hole that penetrates between the outer and inner circumferential surfaces of the second side wall portion in a direction toward the axis, The second cover plate includes, at least a portion of the second cover plate, a communication hole that connects the containment space and the external space. The sealing body is characterized in that the valve body is arranged to close both the space between the first through-hole and the communication hole and the space between the second through-hole and the communication hole in the direction of fluid flow.

2. The sealing body according to claim 1, wherein the first through hole is formed perpendicular to the axis.

3. The sealing body according to claim 1 or 2, wherein the second through hole is formed perpendicular to the axis.

4. A spiral electrode group formed by overlapping a strip-shaped positive electrode plate, a strip-shaped negative electrode plate, and a strip-shaped separator placed between the positive and negative electrode plates, The vortex electrode group is housed together with the electrolyte in a conductive outer casing that has a bottomed cylindrical shape with an opening on one side, The positive electrode plate and the positive electrode terminals electrically connected, A cylindrical storage battery comprising a sealing body according to any one of claims 1 to 3, the sealing body being fixed to the outer can so as to close the opening of the outer can.

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