Sealed battery

Abstract

The purpose of the present disclosure is to provide a sealed battery that, although having a simplified and inexpensive structure, allows a current pathway to be more reliably blocked when a battery abnormality occurs. A sealed battery as an example of an embodiment is provided with an electrode body to which an electrode tab is connected, a closed-end cylindrical outer can which houses the electrode body, and a sealing body that seals an opening of the outer can. The sealing body includes a rupture disk. The rupture disk has a curved first thin-walled portion and a first valve portion surrounded by a straight-line portion connecting both ends of the first thin-walled portion. The first valve portion has a protruding section protruding toward the electrode body, the electrode tab is joined to a side surface of the protruding section, and at least a part of a joint surface between the electrode tab and the protruding section is disposed on a plane crossing the straight-line portion.

Description

[Technical field]

[0001] The present disclosure relates to sealed batteries. [Background technology]

[0002] Conventionally, sealed batteries equipped with a battery case including a cylindrical outer can with a bottom and a sealing body that closes the opening of the outer can have been widely known. For example, Patent Document 1 discloses a cylindrical sealed battery equipped with a sealing body made of a metal plate having a convex downward convex shape on the inside of the battery case. Patent Document 1 describes that when an abnormality occurs in the battery, the sealing body reverses and the welded part between the sealing body and the current collector breaks, thereby cutting off the current and ensuring safety. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-269904 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, with the development of high-energy density sealed batteries, safety in the event of an abnormality has become even more important, and battery designs that can reliably cut off the battery's current path in the event of an abnormality are required. However, at the same time, there is a strong demand for cheaper batteries, and it is essential to reduce costs by simplifying the structure and reducing the number of parts. [Means for solving the problem]

[0005] A sealed battery according to one embodiment of the present disclosure is a sealed battery comprising an electrode body to which an electrode tab is connected, a bottomed cylindrical outer can that houses the electrode body, and a sealing body that closes the opening of the outer can, wherein the sealing body includes a rupture plate, the rupture plate having a first valve portion surrounded by a curved first thin-walled portion and a straight portion connecting both ends of the first thin-walled portion, the first valve portion having a convex portion that protrudes toward the electrode body, the electrode tab is joined to a side surface of the convex portion, and at least a portion of the joining surface between the electrode tab and the convex portion is arranged in a plane that intersects the straight portion.

[0006] Another embodiment of the sealed battery of the present disclosure is a sealed battery comprising an electrode body to which an electrode tab is connected, a bottomed cylindrical outer can that houses the electrode body, and a sealing body that closes an opening of the outer can, wherein the sealing body includes a rupture plate and a connecting member interposed between the rupture plate and the electrode tab, the rupture plate has a first valve portion surrounded by a curved first thin-walled portion and a straight line portion connecting both ends of the first thin-walled portion, the first valve portion has a convex portion that protrudes toward the electrode body, the connecting member is joined to a side surface of the convex portion, the electrode tab is joined to a side surface of the connecting member, and at least a portion of at least one of a first bonding surface between the convex portion and the connecting member and a second bonding surface between the electrode tab and the connecting member is arranged in a plane that intersects the straight line portion. Effect of the Invention

[0007] According to the present disclosure, it is possible to provide a sealed battery that has a simplified and inexpensive structure while more reliably cutting off the current path in the event of an abnormality in the battery. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional view of a sealed battery according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a perspective view of a sealing body according to an embodiment, as viewed from the inner surface side. [Diagram 3] FIG. 3 is a bottom view of the sealing body according to one embodiment. [Figure 4]FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 5 is a diagram showing a state in which the valve part of the sealing body according to one embodiment is open. [Figure 6A] FIG. 6A is a cross-sectional view showing a modified example of the sealing body. [Figure 6B] FIG. 6B is a cross-sectional view showing a modified example of the sealing body. [Figure 7A] FIG. 7A is a diagram for explaining a method for manufacturing a sealed battery according to an embodiment. [Figure 7B] FIG. 7B is a diagram for explaining a method for manufacturing a sealed battery according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] An example of an embodiment of the present disclosure will be described in detail below. In the following, as an example of an embodiment of a sealed battery according to the present disclosure, a cylindrical battery 10 in which a wound electrode body 11 is housed in a bottomed cylindrical outer can 12 will be exemplified, but the battery may be a prismatic battery equipped with a bottomed rectangular tubular outer can. The electrode body may also be a laminated type in which a plurality of positive electrodes and a plurality of negative electrodes are alternately laminated with separators interposed therebetween. In this specification, for convenience of explanation, the sealing body 13 side of the battery case including the outer can 12 and the sealing body 13 will be described as the "upper" and the bottom side of the outer can 12 as the "lower".

[0010] Fig. 1 is a cross-sectional view of a cylindrical battery 10 according to an embodiment. As illustrated in Fig. 1, the cylindrical battery 10 is a cylindrical sealed battery including an electrode assembly 11 connected to an electrode tab, a bottomed cylindrical exterior can 12 that houses the electrode assembly 11, and a sealing body 13 that closes the opening of the exterior can 12. In this embodiment, a grooved portion 16 that protrudes inwardly from the upper end of the exterior can 12 is formed in the upper end of the exterior can 12, and the sealing body 13 is crimped and fixed to the upper end of the exterior can 12 via an insulating gasket 14. The exterior can 12 and the sealing body 13 are both made of metal and are insulated by the gasket 14.

[0011] The electrode body 11 has a wound structure in which a positive electrode and a negative electrode are wound in a spiral shape with a separator interposed therebetween. The positive electrode, the negative electrode, and the separator are all strip-shaped long bodies. A positive electrode tab 15 is connected to the positive electrode, and a negative electrode tab (not shown) is connected to the negative electrode by welding or the like. In this embodiment, the strip-shaped positive electrode tab 15 connected to the longitudinal center of the positive electrode extends from the upper end of the electrode body 11 and is connected to the sealing body 13. The negative electrode tab is connected to at least one of the winding start end and the winding end end of the negative electrode, for example, and is connected to the inner surface of the bottom of the outer can 12. In this case, the sealing body 13 serves as a positive electrode external terminal, and the outer can 12 serves as a negative electrode external terminal. It is also possible to connect the negative electrode tab to the sealing body 13 and connect the positive electrode tab 15 to the outer can 12.

[0012] The positive electrode has a positive electrode core and a positive electrode mixture layer formed on the surface of the positive electrode core. For the positive electrode core, a foil of a metal such as aluminum or an aluminum alloy that is stable in the potential range of the positive electrode, or a film with the metal disposed on the surface layer, can be used. The positive electrode mixture layer contains a positive electrode active material, a conductive agent such as acetylene black, and a binder such as polyvinylidene fluoride (PVdF), and is preferably formed on both sides of the positive electrode core except for the portion to which the positive electrode tab 15 is connected. For example, a lithium transition metal composite oxide is used as the positive electrode active material.

[0013] The negative electrode has a negative electrode core and a negative electrode mixture layer formed on the surface of the negative electrode core. For the negative electrode core, a foil of a metal such as copper or a copper alloy that is stable in the potential range of the negative electrode, or a film with the metal disposed on the surface layer, can be used. The negative electrode mixture layer contains a negative electrode active material and a binder such as styrene butadiene rubber (SBR), and is preferably formed on both sides of the negative electrode core except for the part to which the negative electrode tab is connected. For the negative electrode active material, for example, a carbon-based active material such as graphite, or a Si-based active material containing Si, can be used. Note that a current collecting structure in which the surface of the negative electrode core is in contact with the inner peripheral surface of the exterior can 12 without connecting a negative electrode tab to the negative electrode may be used.

[0014] An insulating plate 17 is disposed between the inner bottom surface of the outer can 12 and the electrode body 11, preventing electrical contact between the positive electrode of the electrode body 11 and the outer can 12. The negative electrode tab extends, for example, through a gap between the outer can 12 and the insulating plate 17 toward the bottom side of the outer can 12. In addition, an insulating spacer 18 is disposed between the sealing body 13 and the electrode body 11. The spacer 18 prevents electrical contact between the negative electrode of the electrode body 11 and the sealing body 13, and adjusts the distance between the electrode body 11 and the sealing body 13. As will be described in detail later, it is preferable that the positive electrode tab 15 is in a taut state without bending so that the current path is easily cut off when an abnormality occurs. The positive electrode tab 15 extends toward the sealing body 13 through a through hole 18a of the spacer 18.

[0015] The outer can 12 contains the electrode assembly 11 and an electrolyte. The electrolyte may be an aqueous electrolyte, but is preferably a non-aqueous electrolyte. The non-aqueous electrolyte includes, for example, a non-aqueous solvent and an electrolyte salt dissolved in the non-aqueous solvent. The non-aqueous solvent may be an ester, an ether, a nitrile, an amide, or a mixed solvent of two or more of these. The non-aqueous solvent may contain a halogen-substituted product in which at least a part of the hydrogen of these solvents is substituted with a halogen atom such as fluorine. The non-aqueous electrolyte is not limited to a liquid electrolyte, and may be a solid electrolyte. The electrolyte salt may be a lithium salt such as LiPF6.

[0016] 2 to 4, the configuration of sealing body 13 and the connection structure between sealing body 13 and positive electrode tab 15 will be described in detail below. Fig. 2 is a perspective view of sealing body 13 as viewed from the inner surface side, Fig. 3 is a bottom view of sealing body 13, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 3.

[0017] As illustrated in Fig. 2 to Fig. 4, the sealing body 13 includes a rupture plate 20 including a valve portion 24, a protrusion 22 protruding from the inner surface of the valve portion 24 toward the electrode body 11, and a connecting member 25 joined to the protrusion 22. The inner surface of the rupture plate 20 (valve portion 24) means the surface facing the electrode body 11. The rupture plate 20 is made of a single metal plate having a thin-walled portion 21 formed therein that breaks when the internal pressure of the battery reaches a predetermined pressure. An example of a suitable metal plate is an aluminum plate or an aluminum alloy plate mainly composed of aluminum.

[0018] The rupture plate 20 has a shape and dimensions that allow it to close the opening of the outer can 12. The rupture plate 20 is, for example, a disk that is a perfect circle when viewed from the bottom. In this embodiment, an annular groove is formed on the inner surface of the rupture plate 20, and the portion where the groove is formed is thinner than other portions and serves as a thin-walled portion 21 that breaks preferentially when the internal pressure of the battery increases. The thin-walled portion 21 has a diameter smaller than the diameter of the rupture plate 20 and is formed in a concentric shape (a perfect circle when viewed from the bottom) with the outer periphery of the rupture plate 20. The thin-walled portion 21 does not necessarily have to be formed in a perfect circle, but is preferably formed in an annular shape.

[0019] The thickness of the rupture plate 20 is not particularly limited, but is, for example, 0.3 mm to 2 mm in the portion other than the thin portion 21 and the protruding portion 22. The thickness of the thin portion 21 is, for example, 10% to 50% of the thickness of the valve portion 24. The thin portion 21 may be formed to have the same thickness over its entire length, but in this embodiment, the first thin portion 21A and the second thin portion 21B, each formed in an arc shape, are connected to form one annular shape. Both the first thin portion 21A and the second thin portion 21B are formed by grooves having a substantially V-shaped cross section, but the remaining thickness of the first thin portion 21A is smaller than the remaining thickness of the second thin portion 21B.

[0020] The portion of the rupture plate 20 surrounded by the thin wall portion 21 is the valve portion 24 that opens to the outside of the battery when the thin wall portion 21 breaks. The valve portion 24 opens when the internal pressure of the battery reaches a predetermined operating pressure (pressure at which the thin wall portion 21 breaks) due to an abnormality in the battery, and prevents the outer can 12 from bursting by discharging gas inside the battery. In this embodiment, the valve portion 24 is formed in a circular shape in bottom view on the portion of the rupture plate 20 excluding the peripheral portion. The valve portion 24 includes two valve portions (a first valve portion 24A and a second valve portion 24B). The thin wall portion 21 is preferably curved and continuous over the entire range, but a part of the thin wall portion 21 may be discontinuous as long as the operation of the valve portion 24 is not hindered. The first valve portion 24A and the second valve portion 24B shown in FIG. 3 have the same area in bottom view, but may have different areas.

[0021] The first valve portion 24A is a portion surrounded by the first thin portion 21A and a straight line α connecting both ends thereof, and is formed in a semicircular shape when viewed from the bottom. Similarly, the second valve portion 24B is a portion surrounded by the arc of the second thin portion 21B and a straight line α connecting both ends thereof, and is formed in a semicircular shape when viewed from the bottom. The first thin portion 21A and the second thin portion 21B may be formed in a curved shape when viewed from the bottom. The first thin portion 21A and the second thin portion 21B are preferably curved convexly toward the outer periphery of the rupture plate 20, and more preferably in an arc shape.

[0022] Since the remaining thickness of the first thin portion 21A is smaller than the remaining thickness of the second thin portion 21B, when the internal pressure of the battery reaches a predetermined pressure, the first valve portion 24A breaks preferentially over the second valve portion 24B. At this time, as shown in FIG. 5, the first valve portion 24A opens outward with the straight line α as the rotation axis. As will be described in detail later, the opening of the first valve portion 24A discharges gas and cuts off the connection between the sealing body 13, which also functions as a positive electrode external terminal, and the positive electrode tab 15, thereby interrupting the current path of the battery. In addition, in order to facilitate the rotation of the first valve portion 24A, a crease line or a shallow groove may be formed along the straight line α. The valve portion 24 can be composed of only the first valve portion 24A, but the gas discharge ability of the valve portion 24 can be increased by combining the first valve portion 24A with the second valve portion 24B. For this reason, it is preferable that the valve portion 24 has the second valve portion 24B in addition to the first valve portion 24A.

[0023] As described above, the protrusion 22 is a protrusion formed on the inner surface of the valve portion 24, and is formed in a circular ring shape along the peripheral edge of the valve portion 24. The protrusion 22 is a portion to which the connecting member 25 is fixed, and is formed with a protruding length that allows the connecting member 25 to be fixed by welding or the like and does not interfere with the electrode body 11. The protrusion 22 has, for example, a side surface along the vertical direction, and a first joint surface 26 with the connecting member 25 is formed on the side surface.

[0024] In this specification, the side surface of the convex portion 22 and the connecting member 25 means a surface facing in a direction intersecting the surface direction of the rupture plate 20, for example, a surface inclined at an angle of 45° or less with respect to the up-down direction perpendicular to the surface direction of the rupture plate 20.

[0025] The protrusion 22 has two slits 23 arranged in the radial direction of the rupture plate 20 at a position overlapping with a straight line α that is the rotation axis of the first valve portion 24A and separates the first valve portion 24A from the second valve portion 24B. The two slits 23 separate the protrusion 22 into a first portion formed in the first valve portion 24A and a second portion formed in the second valve portion 24B. This makes it easier for the first valve portion 24A to open so as to rotate around the straight line α as the rotation axis.

[0026] The connecting member 25 is a conductive member that electrically connects the positive electrode tab 15 and the valve portion 24, and a side surface of one end is joined to a side surface of the protruding portion 22, and a side surface of the other end is joined to the positive electrode tab 15. At least a part of at least one of the first joint surface 26 between the protruding portion 22 and the connecting member 25 and the second joint surface 27 between the positive electrode tab 15 and the connecting member 25 is disposed on a plane intersecting the straight line α. As a result, when the first thin-walled portion 21A opens so as to rotate around the straight line α as a rotation axis, a rotational shear force acts on at least one of the first joint surface 26 and the second joint surface 27. The first joint surface 26 and the second joint surface 27 are formed, for example, by laser welding.

[0027] In this embodiment, one end of the connecting member 25 is joined to a first portion of the protrusion 22 formed in the first valve portion 24A at a position farthest from the straight line α serving as the rotation axis. One end of the connecting member 25 has a curved shape so as to fit along the side surface of the protrusion 22 formed in an annular shape, and the first joint surface 26 is formed along the side surface of the protrusion 22. The center of the first joint surface 26 in the circumferential direction of the protrusion 22 is disposed on a plane that does not intersect with the rotation axis (straight line α) of the first valve portion 24A. Therefore, although a shear force acts in the vertical direction on the center of the first joint surface 26 when the first valve portion 24A opens, no rotational shear force acts on the center of the first joint surface 26.

[0028] On the other hand, both ends of the first joint surface 26 in the circumferential direction of the protrusion 22 are disposed on a plane intersecting the rotation axis of the first valve portion 24A. Therefore, a rotational shear force acts on both ends of the first joint surface 26 when the first valve portion 24A opens. That is, if at least a part of the first joint surface 26 is disposed on a plane intersecting the rotation axis of the first valve portion 24A, a rotational shear force acts on the first valve portion 24A when the first valve portion 24A opens.

[0029] In a bottom view, the connecting member 25 has a shape that gradually widens toward one end joined to the side surface of the protrusion 22. The other end of the connecting member 25 is thinner than the one end, and extends along the radial direction of the rupture plate 20 (valve portion 24) with the side surface of the one end joined along the side surface of the protrusion 22. The connecting member 25 extends from the vicinity of the first thin portion 21A of the first valve portion 24A to the vicinity of the rotation axis of the first valve portion 24A, and is joined to the sealing body 13 only at the first joining surface 26.

[0030] The positive electrode tab 15 is joined to the side surface of the other end of the connecting member 25. In this embodiment, the entire second joint surface 27 of the positive electrode tab 15 and the connecting member 25 is arranged on a plane that is approximately perpendicular to the rotation axis of the first valve portion 24A. Therefore, a large rotational shear force acts on the second joint surface 27 when the first valve portion 24A opens. As with the first joint surface 26, it is sufficient that at least a part of the second joint surface 27 is arranged on a plane that intersects with the rotation axis of the first valve portion 24A. However, it is preferable that the entire second joint surface 27 is arranged on a plane that intersects with the rotation axis of the first valve portion 24A, and it is more preferable that the entire second joint surface 27 is arranged on a plane that intersects with the rotation axis of the first valve portion 24A as in this embodiment.

[0031] Furthermore, the first joint surface 26 is formed in the vicinity of the first thin-walled portion 21A, but the second joint surface 27 is formed closer to the rotation axis of the first valve portion 24A than the first thin-walled portion 21A. The second joint surface 27 is formed, for example, with a constant width along the radial direction of the valve portion 24, from the center of the first valve portion 24A to the vicinity of the rotation axis of the first valve portion 24A (see FIG. 2). The connecting member 25 has a length such that the other end approaches the rotation axis of the first valve portion 24A but does not exceed the rotation axis in order to prevent interference with the second valve portion 24B.

[0032] As shown in Fig. 5, when the first valve portion 24A opens, a rotational shear force acts on a part of the first joint surface 26 between the convex portion 22 and the connecting member 25, but a rotational shear force acts on the entire second joint surface 27 arranged on a plane perpendicular to the rotation axis of the first valve portion 24A. Furthermore, when the first valve portion 24A opens outward with the straight line α as the rotation axis, a second type of lever is formed in which the rotation axis is the fulcrum, the first thin-walled portion 21A is the force point, and the second joint surface 27 is the action point in the cross-sectional view shown in Fig. 4, and a large force acts on the second joint surface 27. Therefore, the second joint surface 27 can be broken more easily than the first joint surface 26.

[0033] As described above, the cylindrical battery 10 having the above-mentioned configuration has a simplified and inexpensive structure, but when an abnormality occurs in the battery, the second joint surface 27 is easily disengaged with the opening of the first valve portion 24A, and the current path is more reliably cut off. For example, the second joint surface 27 formed by laser welding with a width of about 0.5 mm and a length of about 2.5 mm has a vertical welding strength of 30 N or more, but a torque strength of about 20 N·mm. Therefore, if a stress acts on a point 5 mm away from the second joint surface 27 in a direction that rotates the joint surface, the joint surface will break with a force of 4 N. In a conventional general sealed battery, a joint surface with an electrode tab is formed along the surface direction on the bottom surface of the sealing body. In order to apply a tensile stress in a vertical direction to the joint surface to break the joint surface, a force exceeding the welding strength of 30 N is required.

[0034] 6A and 6B are cross-sectional views showing modified examples (sealing bodies 13X and 13Y) of the sealing body 13. In the above-mentioned sealing body 13, annular convex portions 22 are formed on the inner surfaces of the first valve portion 24A and the second valve portion 24B, but in the sealing body 13X shown in FIG. 6A, an arc-shaped convex portion 22X is formed in a bottom view and has a width similar to that of one end portion of the connecting member 25. The convex portion 22X is formed only in the first valve portion 24A, and is gently curved along the first thin portion 21A formed in an arc shape. The convex portion 22X may be formed in a flat plate shape along the rotation axis of the first valve portion 24A.

[0035] 6B differs from the sealing body 13 in that it does not have a connecting member and the positive electrode tab 15 is directly joined to the side surface of the protruding portion 22Y. The side surface of the protruding portion 22Y is formed flat and is disposed on a plane perpendicular to the rotation axis of the first valve portion 24A. As a result, a large rotational shear force acts on the joint surface 27Y formed on the side surface of the protruding portion 22Y with the positive electrode tab 15 when the first thin-walled portion 21A breaks and the first valve portion 24A opens.

[0036] 7A and 7B are diagrams showing the manufacturing process of the cylindrical battery 10. As shown in FIG. 7A, the manufacturing process of the cylindrical battery 10 includes a step of joining the positive electrode tab 15 connected to the electrode body 11 to the sealing body 13. The positive electrode tab 15 is joined to the side surface of the other end of the connecting member 25 by laser welding or the like. One end of the connecting member 25 is joined to the side surface of the protruding portion 22 of the sealing body 13 by laser welding or the like. In addition, a ring-shaped gasket 14 is attached to the peripheral portion of the rupture plate 20 of the sealing body 13.

[0037] Next, as shown in Fig. 7B, with a spacer 18 inserted between the electrode body 11 and the sealing body 13, the electrode body 11 and the electrolyte are housed inside the outer can 12, and the sealing body 13 is placed inside the opening of the outer can 12 so that the sealing body 13 closes the opening at the top end of the outer can 12. In this state, the outer can 12 is crimped from the outside in the radial direction of the sealing body 13, whereby the opening of the outer can 12 is closed by the sealing body 13 via the gasket 14, and a cylindrical battery 10 as shown in Fig. 1 is obtained. An insulating plate 17 is placed between the electrode body 11 and the inner bottom surface of the outer can 12.

[0038] As described above, the spacer 18 prevents electrical contact between the negative electrode of the electrode body 11 and the sealing body 13, and adjusts the distance between the electrode body 11 and the sealing body 13 so that the positive electrode tab 15 is stretched taut without bending. If the positive electrode tab 15 is in an unbent state, the rotational shear force is not absorbed by the bent portion and is easily applied to the second joint surface 27 between the positive electrode tab 15 and the connecting member 25. [Explanation of symbols]

[0039] 10 cylindrical battery, 11 electrode body, 12 outer can, 13, 13X, 13Y sealing body, 14 gasket, 15 positive electrode tab, 16 grooved portion, 17 insulating plate, 18 spacer, 18a through hole, 20 rupture plate, 21 thin portion, 21A first thin portion, 21B second thin portion, 22, 22X, 22Y convex portion, 23 slit, 24 valve portion, 24A first valve portion, 24B second valve portion, 25 connecting member, 26 first joint surface, 27 second joint surface

Claims

1. A sealed battery comprising an electrode assembly to which an electrode tab is connected, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing body that closes an opening of the outer can, The sealing body includes a rupture plate, The rupture plate has an annular thin-walled portion formed of a curved first thin-walled portion and a curved second thin-walled portion connected to both ends of the first thin-walled portion, and has a first valve portion surrounded by straight line portions connecting the first thin-walled portion and both ends of the first thin-walled portion, a remaining thickness of the first thin-walled portion is smaller than a remaining thickness of the second thin-walled portion, the first valve portion has a protrusion protruding toward the electrode body and opens outward about the linear portion as a rotation axis; The electrode tab is joined to a side surface of the protrusion, At least a part of a joint surface between the electrode tab and the protrusion is disposed on a plane intersecting the straight portion.

2. A sealed battery comprising an electrode assembly to which an electrode tab is connected, a cylindrical outer can with a bottom that houses the electrode assembly, and a sealing body that closes an opening of the outer can, The sealing body includes a rupture plate and a connecting member interposed between the rupture plate and the electrode tab, The rupture plate has an annular thin-walled portion formed of a curved first thin-walled portion and a curved second thin-walled portion connected to both ends of the first thin-walled portion, and has a first valve portion surrounded by straight line portions connecting the first thin-walled portion and both ends of the first thin-walled portion, a remaining thickness of the first thin-walled portion is smaller than a remaining thickness of the second thin-walled portion, the first valve portion has a protrusion protruding toward the electrode body and opens outward about the linear portion as a rotation axis; The connecting member is joined to a side surface of the protrusion, The electrode tab is joined to a side surface of the connecting member, A sealed battery, wherein at least a portion of at least one of a first joint surface between the convex portion and the connecting member and a second joint surface between the electrode tab and the connecting member is disposed on a plane intersecting the straight portion.

3. The sealed battery according to claim 1 , wherein the joining surfaces are disposed in a plane perpendicular to the straight line.

4. The sealed battery according to claim 2 , wherein at least one of the first joining surface and the second joining surface is disposed on a plane perpendicular to the straight line.

5. The sealed battery according to any one of claims 1 to 4, wherein the first thin portion has a convex curved shape toward the outer periphery of the rupture plate.

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