WO2011118359A1

WO2011118359A1 - Hermetic battery

Info

Publication number: WO2011118359A1
Application number: PCT/JP2011/054947
Authority: WO
Inventors: 渡辺　修; 森本　充
Original assignee: 日立マクセルエナジー株式会社
Priority date: 2010-03-26
Filing date: 2011-03-03
Publication date: 2011-09-29
Also published as: JP2013140672A

Abstract

In a hermetic battery with a current cutoff function, a structure is obtained that can reduce the variation in pressure values inside the battery in which current is cut off. The hermetic battery (1) comprises: a battery can (10) having a cylindrical shape with a bottom and housing an electrode body (40); a cleavage vent (22) disposed so as to cover the opening side of the battery can (10) and deformed and cleaved by the increase of pressure inside the battery can (10); and a cutoff vent (25) disposed on the battery-can inner side of the cleavage vent (22), electrically connected to the electrode body (40), and also joined with a part of the cleavage vent (22). The cutoff vent (25) is provided with a thin-walled portion (26) having a connection portion (27) joined with the cleavage vent (22). The thin-walled portion (26) has a trench portion (26b) formed so as to surround the connection portion (27), the trench portion (26b) reducing the shear strength of the thin-walled portion (26) compared with that of a welding portion (50).

Description

Sealed battery

The present invention relates to a sealed battery having a current interruption function.

Conventionally, a sealed battery including a bottomed cylindrical outer can and two metal members that are arranged so as to cover the opening of the outer can and are partially joined to each other is known. Such a sealed battery is generally configured so that when a gas is generated inside due to overcharge or the like, the current is cut off inside the battery by separating the two metal members by the pressure of the gas. ing. Specifically, for example, in a sealed battery disclosed in JP-A-5-343043, when a metal thin plate is welded to a safety valve made of a metal plate material and gas is generated inside the battery, the metal thin plate is The welded portion with the safety valve is configured to peel off.

By the way, in the case of the configuration disclosed in the above-mentioned JP-A-5-343043, the force at which the welded part is peeled changes depending on the welding conditions of the two metal members (safety valve, metal thin plate). Therefore, there is a possibility that the pressure value in the battery that interrupts the current inside the battery may vary.

Also, depending on the strength of the two metal members, there is a possibility that the metal parts may break at other locations (for example, a part of the metal thin plate) instead of the welded portions thereof. Therefore, also in this case, there is a possibility that the pressure value in the battery that interrupts the current inside the battery may vary.

An object of the present invention is to obtain a configuration capable of reducing variations in pressure values inside a battery in which a current is interrupted in a sealed battery having a current interrupting function.

A sealed battery according to an embodiment of the present invention is disposed so as to cover a bottomed cylindrical outer can in which an electrode body is housed and an opening side of the outer can, and responds to a pressure increase in the outer can. A cleavage plate that deforms and cleaves, and is disposed on the inside of the outer can of the cleavage plate so as to overlap with the cleavage plate in the thickness direction, and is electrically connected to the electrode body and one of the cleavage plates. A shielding plate that is also joined to the portion, and the shielding plate is provided with a thin-walled portion having a connecting portion to be joined to the cleavage plate, and the thin-walled portion includes the cleavage portion of the connecting portion. A groove portion that lowers the shear strength of the thin-walled portion is formed so as to surround the connecting portion as compared with the joint portion with the plate (first configuration).

With this configuration, even when gas is generated inside the sealed battery due to overcharge or the like, it is not separated at the joint between the cleavage plate and the shielding plate, but is broken at the groove formed in the thin portion of the shielding plate. To do. That is, since the shear strength around the groove portion of the shield plate is lower than the joint portion between the cleavage plate and the shield plate, the groove portion is ruptured regardless of the joining condition of the connection portion. Therefore, when the internal pressure of the sealed battery reaches a certain value, the current can be cut off in the sealed battery by separating the cleavage plate and the blocking plate.

In the first configuration, the thin portion is formed with a plurality of through-hole portions penetrating the thin-wall portion in the thickness direction, and the groove portion connects the plurality of through-hole portions to each other. It is preferable to be provided in the part (second configuration).

Therefore, when the pressure in the sealed battery is increased and the cleavage plate is deformed, the blocking plate is easily broken at the groove. That is, since the shear strength around the groove is further reduced by the through hole formed in the thin portion, the blocking plate is more reliably broken at the groove.

In the first or second configuration, the cleavage plate is formed with a bulging portion that bulges toward the thin portion of the blocking plate and contacts the connecting portion of the thin portion. It is preferable to be provided inside the bulging portion as viewed from the stacking direction of the cleavage plate and the blocking plate (third configuration).

By doing so, the cleavage plate can be reliably brought into contact with the connecting portion of the blocking plate, and the cleavage plate and the blocking plate can be more reliably joined at the connecting portion. Then, by providing the groove portion on the inner side of the bulging portion when viewed from the stacking direction of the cleavage plate and the blocking plate, the thin portion is pressed by the bulging portion when the cleavage plate and the blocking plate are brought into contact with each other. Even if it is deformed, it can be prevented from breaking at the groove. Further, by providing the groove portion on the inner side of the bulging portion as described above, the groove portion can be broken with a smaller force than when the groove portion is provided on the outer side of the bulging portion. After breaking at the groove, the length of the blocking plate attached to the cleavage plate side can be shortened. Thereby, according to the pressure rise inside the sealed battery, the breaker plate is more reliably broken at the groove, and after the breakage, a part of the breaker plate attached to the cleavage plate side and the remaining breaker plate Can be prevented from continuing to flow in the battery due to contact.

In any one of the first to third configurations, it is preferable that the connection portion is formed thinner than the other portions of the thin portion (fourth configuration). Thereby, since it becomes possible to make comparatively big thickness except a connection part of a thin part, it can prevent that it fractures | ruptures in thin parts other than a groove part. Since the connecting portion is formed thinner than the other portions so as to have an appropriate thickness that provides high bonding strength, the blocking plate can be more reliably bonded to the cleavage plate at the connecting portion.

In any one of the first to fourth configurations, it is preferable that the thin portion and the groove portion of the blocking plate are formed by coining (fifth configuration). Thereby, the shielding board which has a thin part and a groove part can be formed at low cost. In the case of the shielding plate formed by coining, work hardening occurs, and therefore, when stress concentrates on the work hardened portion, it tends to break. On the other hand, by applying the first to fourth configurations, the shielding plate is broken at the groove portion, so that variation in pressure inside the battery where the cleavage plate and the shielding plate are separated can be suppressed.

According to the sealed battery according to the embodiment of the present invention, the groove portion having a lower shear strength than the joining portion between the cleavage plate and the shielding plate is formed in the thin portion of the shielding plate joined to a part of the cleavage plate. Since it is provided so as to surround the connecting portion, it is possible to reduce variations in the pressure value inside the battery where the cleavage plate and the blocking plate are separated.

FIG. 1 is a perspective view showing a schematic configuration of a sealed battery sealing body according to an embodiment of the present invention. 2 is a cross-sectional view taken along line II-II in FIG. FIG. 3 is a bottom view of the blocking vent. 4 is a cross-sectional view taken along line IV-IV in FIG. FIG. 5 is an enlarged view showing a thin portion of the blocking vent. FIG. 6 is an enlarged cross-sectional view showing an enlarged welded portion between the blocking vent and the cleavage vent.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are denoted by the same reference numerals and description thereof will not be repeated.

(overall structure)
FIG. 1 is a diagram showing a schematic configuration of a sealed battery 1 according to an embodiment of the present invention. In the sealed battery 1, a sealing body 20 is attached to the opening side of a bottomed cylindrical battery can 10 (exterior can). Specifically, as shown in a cross-section in FIG. 2, the sealed battery 1 is disposed between the battery can 10, the sealing body 20, the opening end portion 11 a of the battery can 10, and the outer peripheral side of the sealing body 20. A gasket 30 and an electrode body 40 housed in a space formed by the battery can 10 and the sealing body 20 are provided. In the space formed between the battery can 10 and the sealing body 20, in addition to the electrode body 40, a nonaqueous electrolytic solution (not shown) is also enclosed.

The battery can 10 is made of a metal material such as a steel plate or stainless steel whose surface is nickel-plated, and is formed into a bottomed cylindrical shape by press molding. That is, the battery can 10 is formed by integrally forming a circular bottom portion (not shown) and a cylindrical peripheral wall portion 11. A negative electrode tab (not shown) extending from the electrode body 40 is connected to the bottom of the battery can 10. That is, in the present embodiment, the battery can 10 functions as a negative electrode terminal of the sealed battery 1. Note that the battery can 10 may be used as the positive electrode terminal.

The open end portion 11 a of the peripheral wall portion 11 of the battery can 10 is caulked to the sealing body 20 via the gasket 30. That is, in the state where the sealing body 20 and the gasket 30 are disposed inside the battery can 10, the open end 11 a of the battery can 10 is bent toward the inside of the battery can. Thereby, the sealing body 20 is fixed to the opening side of the battery can 10.

The sealing body 20 includes a terminal plate 21 as a positive electrode terminal, a cleavage vent 22 (a cleavage plate) that is deformed and cleaved in response to a rise in pressure inside the battery, and a cutoff vent 25 (functioning as a current cutoff mechanism together with the cleavage vent 22). A shielding plate). In the sealing body 20 in this embodiment, a resistance plate 23 whose resistance changes according to temperature is disposed between the terminal plate 21 and the cleavage vent 22. In the present embodiment, the terminal plate 21 functions as a positive electrode terminal. However, when the battery can 10 functions as a positive electrode terminal, the terminal plate 21 functions as a negative electrode terminal.

The terminal plate 21 is made of a material in which the surface of a rolled steel plate is nickel-plated, and is formed in a substantially hat shape having an annular flange 21a on the outer peripheral side. That is, a convex portion 21 b that bulges into a bottomed cylindrical shape toward the outside of the battery can 10 is formed at the center portion of the terminal plate 21. A plurality of gas discharge holes 21c are provided on the outer peripheral side of the convex portion 21b. In the present embodiment, as shown in FIG. 1, the gas discharge holes 21c are provided at a total of four locations at intervals of approximately 90 degrees in the circumferential direction on the outer peripheral side of the convex portion 21b.

As shown in FIG. 2, the cleavage vent 22 is a member made of aluminum and is formed in a substantially hat shape like the terminal plate 21. That is, the cleavage vent 22 includes a cleavage portion 22a that swells into a bottomed cylindrical shape, and a flange portion 22b that is positioned on the outer peripheral side of the cleavage portion 22a. The cleavage vent 22 is disposed in the battery can 10 in a reverse hat shape with respect to the terminal plate 21 so that the cleavage portion 22a bulges toward the inner side of the battery can 10.

In the cleavage portion 22a, a bulging portion 22c that bulges in the bulging direction of the cleavage portion 22a is formed at the center portion. Further, a groove portion 22d having a substantially V-shaped cross section is provided in an annular shape on the inner bottom surface of the cleavage portion 22a so as to surround the central bulge portion 22c. Further, four groove portions 22e having a substantially V-shaped cross section are provided on the bottom surface inside the cleavage portion 22a so as to extend in a cross shape from the annular groove portion 22d in plan view (not shown).

Thus, by providing the

groove portions

22d and 22e on the bottom surface of the cleavage portion 22a of the cleavage vent 22, when the internal pressure of the sealed battery 1 rises to a predetermined pressure (for example, the internal pressure is 2.5 MPa), The cleavage vent 22 is broken at the

groove portions

22d and 22e. As described above, by configuring the cleavage vent 22 to break at the

groove portions

22d and 22e according to the pressure inside the sealed battery 1, it is possible to prevent the battery can 10 from being ruptured due to an increase in pressure inside the battery.

The resistance plate 23 is formed by, for example, sandwiching a conductive polymer sheet between two metal electrode foils, and is configured such that the resistance increases as the temperature inside the battery rises. The resistance plate 23 is formed in an annular shape so as to be sandwiched between the flange portion 21 a of the terminal plate 21 and the flange portion 22 b of the cleavage vent 22. Thereby, when the temperature in the sealed battery 1 becomes equal to or higher than a predetermined value, the resistance plate 23 suppresses a current from flowing between the cleavage vent 22 and the terminal plate 21. On the other hand, when the temperature decreases, the resistance plate 23 decreases in resistance value and returns to the original conductive state.

With the resistance plate 23 sandwiched between the flange portion 21 a of the terminal plate 21 and the flange portion 22 b of the cleavage vent 22, the opening portions of the peripheral wall portion 11 of the battery can 10 are sandwiched between the

flange portions

21 a and 22 b and the resistance plate 23. The part 11a is caulked. Accordingly, the resistance plate 23 can be fixed to the opening side of the battery can 10 while being held between the terminal plate 21 and the cleavage vent 22.

The blocking vent 25 is a member made of aluminum and is formed in a bottomed cylindrical shape so as to cover the cleavage portion 22a of the cleavage vent 22. That is, the blocking vent 25 includes a circular bottom surface portion 25a and a peripheral wall portion 25b formed on the outer peripheral side of the bottom surface portion 25a. The opening end side of the peripheral wall portion 25b is held by the cylindrical cleaving portion 22a of the cleaving vent 22 by an annular holding member 24 made of an insulating material.

The holding member 24 is a member made of polybutylene terephthalate (PBT) or polypropylene (PP). Therefore, the holding member 24 can insulate the cleavage vent 22 and the blocking vent 25 except for the welded portion 50 described later.

As shown in FIG. 3, a plurality (six in this embodiment) of through holes 25 c are formed at equal intervals in the circumferential direction on the bottom surface portion 25 a of the blocking vent 25. These through holes 25c are gas vent holes through which gas generated by overcharging or the like in the battery can 10 passes. By providing these through holes 25 c, gas passes through the blocking vent 25 and pressure is applied to the cleavage portion 22 a of the cleavage vent 22.

Further, as will be described in detail later, a part of the bottom surface portion 25 a of the blocking vent 25 is welded (joined) to the cleavage portion 22 a of the cleavage vent 22. Further, a positive electrode tab 45 extending from the electrode body 40 is connected to the blocking vent 25 (see FIG. 2). That is, the electrode body 40, the blocking vent 25, and the cleavage vent 22 are electrically connected. As described above, when the internal pressure of the sealed battery 1 is increased and the cleavage portion 22a of the cleavage vent 22 is deformed, the cleavage portion 22a is separated from the cutoff vent 25, and the current in the sealed battery 1 is cut off. . That is, in this embodiment, the interruption vent 25 functions as a current interruption mechanism together with the cleavage vent 22.

The detailed configuration of the blocking vent 25 will be described later.

The gasket 30 is a substantially cylindrical member made of polybutylene terephthalate (PBT) or polypropylene (PP). The gasket 30 is provided with a step portion 31 at the center portion in the cylinder axis direction so that the diameter of the end portion on one side is larger than the diameter of the end portion on the other side. That is, the gasket 30 has a large-diameter portion 33, a small-diameter portion 32, and a step portion 31 positioned therebetween. The large diameter portion 33 has an inner diameter larger than the outer diameter of the sealing body 20 so that the sealing body 20 can be accommodated. The sealing body 20 is accommodated in the large diameter portion 33 of the gasket 30 so as to support the sealing body 20 by the step portion 31, and the opening end 10 a of the peripheral wall portion 10 of the battery can 10 is sealed together with the opening side of the large diameter portion 33. By caulking, the gasket 30 is sandwiched between the battery can 10 and the sealing body 20 as shown in FIG.

The electrode body 40 is wound in a spiral shape in a state where a sheet-like positive electrode and a negative electrode are laminated in the thickness direction via a separator, although not particularly illustrated. In the electrode body 40, the positive electrode has a positive electrode active material, while the negative electrode has a negative electrode active material, and is configured to be chargeable / dischargeable. Detailed configurations of the positive electrode, the negative electrode, and the separator are the same as those in the related art, and thus detailed description thereof is omitted. The positive electrode of the electrode body 40 is electrically connected to the blocking vent 25 via the positive electrode tab 45 on the opening end side of the battery can 10. On the other hand, the negative electrode of the electrode body 40 is electrically connected to the battery can 10 by a negative electrode tab (not shown) on the bottom side of the battery can 10.

Examples of the positive electrode active material used for the positive electrode include lithium cobalt oxide such as LiCoO ₂ , lithium manganese oxide such as LiMn ₂ O ₄ , lithium nickel oxide such as LiNiO ₂ , manganese dioxide, vanadium pentoxide, and chromium oxide. Metal oxides such as materials, and metal sulfides such as titanium disulfide and molybdenum disulfide are used.

On the other hand, the negative electrode active material used for the negative electrode may be any material that can dope and dedope lithium ions. For example, as a negative electrode active material, graphite, pyrolytic carbons, cokes, glassy carbons, organic polymer compound fired bodies, mesocarbon microbeads, carbon fibers, activated carbon and other carbon materials, Si, Sn, In, etc. It is preferable to use an alloy of Si, Sn, In or the like that can be charged and discharged at a low voltage close to Li.

(Blocking vent)
Below, the structure of the interruption | blocking vent 25 which functions as an electric current interruption | blocking mechanism with the cleavage vent 22 is demonstrated in detail using FIGS. 3 is a bottom view of the blocking vent 25, FIG. 4 is a sectional view taken along line IV-IV in FIG. 3, FIG. 5 is an enlarged view of a central portion of the bottom portion 25a of the blocking vent 25, and FIG. It is an expanded sectional view of the welding part 50 with the cleavage vent 22. FIG.

As shown in FIGS. 3 to 6, a thin portion 26 is provided at the center of the bottom surface (outer surface) of the bottom surface portion 25a. The thin portion 26 is formed by thinning the central portion of the bottom surface of the bottom surface portion 25a in a step shape. The thin portion 26 is formed in a circular shape in plan view. Further, a connection portion 27 formed to be thinner is provided at the central portion of the thin portion 26. The connecting portion 27 is formed in a circular shape in plan view, and is joined to the bulging portion 22c of the cleavage portion 22a of the cleavage vent 22 by YAG laser welding or the like, as shown in FIG. Thereby, the welding part 50 (joining part) is formed in the connection part 27 and the bulging part 22c.

As shown in FIGS. 3 and 5, a plurality of (three in this embodiment) through-hole portions 26 a are formed in the thin portion 26 so as to surround the connection portion 27. Each through-hole portion 26 a is an elongated hole formed in an arc shape with the connection portion 27 as the center, and is provided at the same position in the radial direction of the blocking vent 25 with respect to the connection portion 27. Furthermore, a plurality of groove portions 26b are formed in the thin portion 26 so as to surround the connection portion 27 and connect the plurality of through-hole portions 26a. Specifically, each groove 26b is formed in a substantially V-shaped cross section so that the width of the groove bottom is smaller than the groove width on the opening side. Moreover, each groove part 26b is formed so that it may mutually connect in the radial direction inner side part of the interruption | blocking vent 25 in the through-hole part 26a, as expanded and shown in FIG. Furthermore, each groove part 26b is formed so that the groove width on the opening side is smaller than the length in the short direction of the opening of the through hole part 26a.

In this way, by providing the groove portion 26b so as to connect the plurality of through-hole portions 26a, the shear strength of the groove bottom portion of the groove portion 26b is set to the welded portion 50 between the bulging portion 22c of the cleavage vent 22 and the connection portion 27. It can be made smaller than the shear strength. Therefore, when gas is generated in the sealed battery 1 due to overcharge or the like and the cleavage vent 22 is deformed to the terminal plate 21 side, the connection portion 27 welded to the cleavage vent 22 is connected to the terminal plate 21 side together with the cleavage vent 22. When it is pulled, the blocking vent 25 is broken at the groove 26b. That is, since the fracture is caused not by the welded portion 50 between the cleavage vent 22 and the blocking vent 25 but by the groove portion 26b of the blocking vent 25, the pressure inside the sealed battery 1 is not affected by the joining conditions such as welding. When reaching a certain value (for example, 1.4 MPa), the cleavage vent 22 and the blocking vent 25 can be separated.

Further, the blocking vent 25 having the above-described configuration is formed by coining. Therefore, the blocking vent 25 can be formed at a lower cost than the configuration using the metal foil. However, when the blocking vent 25 is formed by coining, work hardening occurs at the outer peripheral edge portion of the thin portion 26, and breakage tends to occur due to stress concentration. If it does so, dispersion | variation will arise in the force which the interruption | blocking vent 25 fractures | ruptures. On the other hand, by providing the groove part 26b as described above, the blocking vent 25 can be broken at the groove part 26b. Therefore, even when the blocking vent 25 is formed by coining, the cleavage vent 22 and the blocking vent 25 can be separated by the groove portion 26b when the internal pressure of the battery reaches a certain value.

Furthermore, as shown in FIG. 6, each groove portion 26 b is in plan view (in the state where the bulging portion 22 c of the cleavage vent 22 is pressed against the thin portion 26 of the interruption vent 25). , As viewed from the stacking direction), and is formed inside the bulging portion 22c.

In order to join the connecting portion 27 of the thin portion 26 of the blocking vent 25 and the bulging portion 22c of the cleavage vent 22 by YAG laser welding or the like, it is necessary to make the gap between the bulging portion 22c and the connecting portion 27 as small as possible. There is. For this purpose, it is necessary to press the bulging portion 22c against the thin-walled portion 26. However, if the groove portion 26b is formed outside the bulging portion 22c in a plan view, stress concentrates on the groove portion 26b and the There is a possibility of breaking at the groove 26b. On the other hand, by providing the groove portion 26b at the position as described above, when the bulging portion 22c is pressed against the thin portion 26, a large force is not applied to the groove portion 26b, thereby preventing the groove portion 26b from breaking. it can.

Further, by providing the groove 26b at the position as described above, the groove 26b is close to the connecting portion 27. Therefore, when the groove 26b breaks, the portion of the blocking vent 25 that adheres to the cleavage vent 22 side is removed. Can be small. As a result, it is possible to prevent a part of the blocking vent 25 attached to the cleavage vent 22 side from contacting the remaining part of the blocking vent 25 and causing a current to continue flowing in the sealed battery 1.

Furthermore, by providing the groove portion 26b at the position as described above, the blocking vent 25 can be broken at the groove portion 26b with a smaller force than when the groove portion is provided outside the bulging portion 22c in plan view. . That is, when the groove portion 26b is far from the connection portion 27, the distance of the groove portion 26b is increased correspondingly, and the shear strength of the groove bottom portion is also increased. However, by providing the groove portion 26b closer to the connection portion 27, it is small. Even with pressure, the blocking vent 25 can be more reliably broken by the groove 26b.

(Operation of cleavage vent and blocking vent)
Next, the operation of the cleavage vent 22 and the blocking vent 25 having the above-described configuration under high pressure conditions will be described below.

When an abnormality such as overcharge occurs in the sealed battery 1 and the pressure in the battery can 10 increases, the cleavage vent 22 is deformed to the terminal plate 21 side by the pressure. And if the pressure in the battery can 10 becomes 1.4 MPa, the interruption | blocking vent 25 will fracture | rupture in the groove part 26b, and this interruption | blocking vent 25 and the cleavage vent 22 will isolate | separate. As a result, no current flows between the blocking vent 25 and the cleavage vent 22, and no current flows in the sealed battery 1.

Further, when the pressure in the battery can 10 rises and the pressure in the battery can 10 reaches 2.5 MPa, the cleavage vent 22 breaks at the

groove portions

22d and 22e. Thereby, the cleavage vent 22 is cleaved, and the gas and the electrolyte in the battery can 10 are ejected from the hole formed in the cleavage vent 22 to the outside.

As described above, by operating the cleavage vent 22 and the shutoff vent 25, it is possible to cut off the current according to the pressure increase in the sealed battery 1, and to prevent the battery can 10 from being ruptured by the internal pressure.

(Effect of embodiment)
With the above configuration, since the groove portion 26b for lowering the shear strength than the welded portion 50 with the cleavage vent 22 is provided in the thin wall portion 26 of the interruption vent 25 so as to surround the connection portion 27, the interruption vent 25 is provided in the groove portion 26b. Can be broken. Therefore, the interruption vent 25 and the cleavage vent 22 can be separated by the groove 26b when the internal pressure in the battery can 10 reaches a predetermined value without being affected by the welding conditions of the welded portion 50 and the like. That is, with the above-described configuration, it is possible to reduce variations in the pressure value in the battery can 10 where the blocking vent 25 and the cleavage vent 22 are separated.

Further, as seen from the stacking direction of the blocking vent 25 and the cleavage vent 22, the groove portion 26 b is provided on the inner side of the bulging portion 22 c of the cleavage vent 22, so that the bulging portion 22 c is a thin-walled portion 26 of the blocking vent 25. It is possible to prevent the groove 26b from being broken when pressed against. In addition, with this configuration, when the groove 26b breaks, the length of a part of the blocking vent 25 attached to the cleavage vent 22 side can be relatively shortened. It is possible to prevent a short circuit due to contact between the portion and the remaining portion of the blocking vent 25. Furthermore, since the groove part 26b is formed at a position relatively close to the coupling part 27, the blocking vent 25 can be broken at the groove part 26b with a relatively small force.

Furthermore, the groove 26b is provided so as to connect a plurality of through holes 26a provided in the thin portion 26 of the blocking vent 25. Therefore, the shear strength of the groove bottom portion of the groove portion 26 b can be reduced as compared with the welded portion 50 between the blocking vent 25 and the cleavage vent 22. Therefore, the blocking vent 25 can be more reliably broken at the groove 26b.

(Other embodiments)
While the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

In the above embodiment, three through holes 26 a are formed in the thin portion 26 of the blocking vent 25. However, the number of the through holes 26a may be two or less or four or more as long as the blocking vent 25 is broken at the groove 26b when the cleavage vent 22 is deformed. May not be provided. When the through-hole portion is not provided, for example, by making the cross-sectional shape of the groove portion 26b easier to break, or by providing the groove portion 26b closer to the connecting portion 27, the groove portion 26b can be more easily broken. There is a need.

In the above-described embodiment, the cross-sectional shape of the groove 26b provided in the thin portion 26 of the blocking vent 25 is substantially V-shaped. However, other cross-sectional shapes may be used as long as the cross-sectional shape is broken at the groove 26b.

In the above-described embodiment, the groove portion 26b is provided on the bottom surface outside the blocking vent 25 (the inner surface of the battery can 10). However, the groove 26b may be provided on the bottom surface inside the blocking vent 25 (the surface on the side of the cleavage vent 22).

In the above embodiment, the connecting portion 27 of the blocking vent 25 and the bulging portion 22c of the cleavage vent 22 are joined by welding. However, any method other than welding may be used as long as the members can be joined together.

In the above embodiment, the resistance plate 23 is provided between the cleavage vent 22 and the terminal plate 21. However, the cleavage vent 22 and the terminal plate 21 may be brought into direct contact without providing the resistance plate 23.

The sealed battery according to the present invention can be used for a sealed battery having a current interruption function.

Claims

A bottomed cylindrical outer can in which an electrode body is stored;
A cleavage plate that is arranged so as to cover the opening side of the outer can, and is deformed and cleaved in response to a pressure increase in the outer can;
A blocking plate that is arranged on the inner side of the outer can of the cleavage plate so as to overlap the cleavage plate in the thickness direction, and is electrically connected to the electrode body and also joined to a part of the cleavage plate; With
The blocking plate is provided with a thin portion having a connection portion joined to the cleavage plate,
A sealed battery, wherein the thin-walled portion is formed with a groove portion that lowers the shear strength of the thin-walled portion so as to surround the connecting portion, rather than a joint portion of the connecting portion with the cleavage plate.
The sealed battery according to claim 1,
In the thin wall portion, a plurality of through-hole portions penetrating the thin wall portion in the thickness direction are formed,
The groove portion is a sealed battery provided in the thin portion so as to connect the plurality of through-hole portions.
The sealed battery according to claim 1 or 2,
The cleavage plate is formed with a bulging portion that bulges toward the thin portion of the blocking plate and contacts the connecting portion of the thin portion,
The said groove part is a sealed battery provided in the inner side rather than the said bulging part seeing from the lamination direction of the said cleavage plate and the interruption | blocking board.
The sealed battery according to any one of claims 1 to 3,
The said connection part is a sealed battery formed further thinly compared with the other part of the said thin part.
The sealed battery according to any one of claims 1 to 4,
The thin-walled portion and the groove portion of the blocking plate are sealed batteries formed by coining.