Safety valve, exterior body, and battery

Abstract

This safety valve (530) includes: a central portion (531) formed in a rectangular shape in a recess (520f) of an exterior body (lid 520); one end portion (532) that is continuous with the central portion (531) in the recess portion (520f) and formed in a semicircular shape on the side of one end (531p) of the central portion (531) along a first direction (longitudinal direction X); and another end portion (533) that is continuous with the central portion (531) in the recess portion (520f) and formed in a semicircular shape on the side of another end (531q) of the central portion (531) along the first direction. A first groove (531a) and a second groove (531b) of the safety valve (530) are formed in a linear shape, a third groove (532c) and a fourth groove (533d) are formed in an arc shape, and the thickness of the first groove (531a) is greater than the thickness of the second groove (531b), the third groove (532c), and the fourth groove (533d).

Description

Safety valve, exterior body and battery

[0001] The present invention relates to a safety valve, an exterior body, and a battery.

[0002] Safety valves for batteries have been known for some time (see, for example, Patent Documents 1 to 3). The safety valve is provided in the battery housing. The safety valve ruptures toward the outside of the battery when the internal pressure of the battery reaches a predetermined value.

[0003] Japanese Patent Application Laid-Open No. 2004-111155 Japanese Patent Application Laid-Open No. 2000-285892 Japanese Patent No. 4716538

[0004] There is a need for a safety valve that can be sufficiently ruptured under a predetermined pressure while remaining in the exterior case, as well as an exterior case and a battery having such a safety valve.

[0005] The safety valve of the present invention is a safety valve provided in a battery having a charging / discharging unit and an exterior body that houses the charging / discharging unit and extends along a first direction. The exterior body includes a recess that includes: a first inner edge that is linearly formed along the first direction on one side of a second direction intersecting the first direction; a second inner edge that is linearly formed along the first direction on the other side of the second direction and faces the first inner edge along the second direction; a third inner edge that is arc-shaped and connected to the first and second inner edges; and a fourth inner edge that is arc-shaped and faces the third inner edge along the first direction. The safety valve has a central portion formed in a rectangular shape in the recess of the exterior body, a first end portion connected to the central portion in the recess and formed in a semicircular shape on one end side of the central portion along the first direction, and a second end portion connected to the central portion in the recess and formed in a semicircular shape on the other end side of the central portion along the first direction. The central portion, the first end portion, and the second end portion are thinner than the exterior body. The central portion includes a first groove formed in a concave shape adjacent to the first inner edge and a second groove formed in a concave shape adjacent to the second inner edge. The first end portion includes a third groove formed in a concave shape adjacent to the third inner edge and connected to the first and second grooves. The second end portion includes a fourth groove formed in a concave shape adjacent to the fourth inner edge and connected to the first and second grooves. The first and second grooves are formed in a linear shape. The third and fourth grooves are formed in an arc shape. The thickness of the first groove is greater than the thicknesses of the second groove, the third groove, and the fourth groove.

[0006] The present invention provides an exterior housing that houses a charge / discharge device and extends along a first direction. The exterior housing includes a recess and a safety valve. The recess includes a first inner edge that is linearly formed along the first direction on one side of a second direction intersecting the first direction, a second inner edge that is linearly formed along the first direction on the other side of the second direction and faces the first inner edge along the second direction, a third inner edge that is connected to the first inner edge and the second inner edge and formed in an arc shape, and a fourth inner edge that faces the third inner edge along the first direction and faces the third inner edge along the first direction and is connected to the first inner edge and the second inner edge and formed in an arc shape. The safety valve includes a central portion that is rectangular in the recess of the exterior housing, one end portion that is connected to the central portion in the recess and formed in a semicircular shape on one end side of the central portion along the first direction, and a second end portion that is connected to the central portion in the recess and formed in a semicircular shape on the other end side of the central portion along the first direction. The central portion, the one end portion, and the other end portion are thinner than the exterior body. The central portion includes a first groove formed concavely adjacent to the first inner edge and a second groove formed concavely adjacent to the second inner edge. The one end portion includes a third groove connected to the first groove and the second groove and formed concavely adjacent to the third inner edge. The other end portion includes a fourth groove connected to the first groove and the second groove and formed concavely adjacent to the fourth inner edge. The first groove and the second groove are formed linearly. The third groove and the fourth groove are formed arc-shaped. The thickness of the first groove is thicker than the thicknesses of the second groove, the third groove, and the fourth groove.

[0007] The battery of the present invention includes a charging / discharging unit, an exterior body that houses the charging / discharging unit and extends along a first direction, and a safety valve provided in the exterior body. The exterior body includes a recess. The recess includes: a first inner edge that is linearly formed along the first direction on one side of a second direction that intersects the first direction; a second inner edge that is linearly formed along the first direction on the other side of the second direction and faces the first inner edge along the second direction; a third inner edge that is arc-shaped and connected to the first and second inner edges; and a fourth inner edge that is arc-shaped and faces the third inner edge along the first direction and faces the third inner edge along the first direction. The safety valve includes a central portion formed in a rectangular shape in the recess of the exterior body, a first end portion connected to the central portion in the recess and formed in an arc shape on one end side of the central portion along the first direction, and a second end portion connected to the central portion in the recess and formed in an arc shape on the other end side of the central portion along the first direction. The central portion, the first end portion, and the second end portion are thinner than the exterior body. The central portion includes a first groove formed in a concave shape adjacent to the first inner edge and a second groove formed in a concave shape adjacent to the second inner edge. The first end portion includes a third groove formed in a concave shape adjacent to the third inner edge and connected to the first groove and the second groove. The other end portion includes a fourth groove formed in a concave shape adjacent to the third inner edge and connected to the first groove and the second groove. The length of the central portion along the first direction is 1 mm or more, and the length of the central portion is 0.5 to 3 times the diameter of the one end and the other end. The thickness of the second groove, the third groove, and the fourth groove is 0.2 to 0.7 times the thickness of the first groove.

[0008] It is possible to obtain a safety valve that can be sufficiently ruptured under a predetermined pressure while remaining in the exterior body, as well as an exterior body and a battery that include the safety valve.

[0009] 12 is a perspective view showing a battery 1 according to an embodiment; a perspective view showing, in cross section, components around the negative terminal 420 of the battery 1; a side view showing the components of FIG. 2; a perspective view showing, in cross section, components around the positive terminal 410 of the battery 1; a side view showing the components of FIG. 4; a perspective view showing a partially exploded view of the battery 1; a perspective view showing a charging / discharging body 100 of the battery 1; a side view showing, in cross section, a portion of the charging / discharging body 100 of FIG. 7; a side view showing, in cross section, a portion of a charging / discharging body 1100 of a modified example; an exploded perspective view showing components around the negative terminal 420 of the battery 1; an exploded perspective view showing components around the positive terminal 410 of the battery 1; an exploded perspective view showing components around the safety valve 530 and sealing plug 540 of the battery 1; a top view showing the safety valve 530 and lid 520 of FIG. 12. 17 is a perspective view showing a cross section of the safety valve 530 and the lid 520 of FIG. 13 taken along the longitudinal direction X. A perspective view showing region 15 of FIG. 14. A perspective view showing region 16 of FIG. 14. A perspective view showing a cross section of the safety valve 530 and the lid 520 of FIG. 13 taken along the lateral direction Y. A perspective view showing region 18 of FIG. 17. A perspective view showing region 19 of FIG. 17. A schematic view showing the relationship between the rupture pressure: P of the safety valve 530 and the thickness: t of the second groove 531b, the third groove 532b, and the fourth groove 533d of the safety valve 530. A schematic view showing the relationship between the force applied to the first groove 531a of the safety valve 530 and the elongation of the first groove 531a of the safety valve 530. A graph showing the results of simulating the displacement region and displacement amount of the second groove 531b of the safety valve 530 under conditions 1 to 9 in Table 1. 1. A graph showing the results of a simulation of the maximum value of the displacement region of the second groove 531b of the safety valve 530 under conditions 1 to 9 in Table 1. Photographs showing the results of an experiment under condition 14 in Table 2. Simulation images under condition 14 in Table 2. Photographs showing the results of an experiment under condition 16 in Table 2. Simulation images under condition 16 in Table 2. A perspective view showing a cross section of a safety valve 810 and a lid 520 according to a first modified example of the embodiment. A perspective view showing a cross section of a safety valve 820 and a lid 520 according to a second modified example of the embodiment. A perspective view showing a cross section of a safety valve 830 and a lid 520 according to a third modified example of the embodiment. A perspective view showing a cross section of a safety valve 840 and a lid 520 according to a fourth modified example of the embodiment. A perspective view showing a cross section of a safety valve 850 and a lid 520 according to a fifth modified example of the embodiment. A perspective view showing a cross section of a safety valve 860 and a lid 520 according to a sixth modified example of the embodiment.

[0010] Embodiments of the present invention will be described with reference to the drawings. To facilitate understanding of each embodiment, the size and proportions of components may be exaggerated in each drawing. The same reference numerals are used for the same components in each drawing. In each drawing, the longitudinal direction X, lateral direction Y, and height direction Z of the battery 1 are indicated by arrows. In each drawing, the longitudinal direction X, lateral direction Y, and height direction Z of the battery 1 indicate the relative positional relationship within the same drawing. That is, if the battery 1 is rotated 180 degrees and placed with the top and bottom sides reversed, or if the battery 1 is rotated 90 degrees and placed with the top side facing sideways, the longitudinal direction X, lateral direction Y, and height direction Z of the battery 1 will change.

[0011] (Configuration of Battery 1 of the Embodiment) The configuration of the battery 1 will be described with reference to FIGS. 1 to 19. FIG.

[0012] FIG. 1 is a perspective view showing a battery 1 according to an embodiment. FIG. 2 is a perspective view showing a cross section of components around the negative terminal 420 of the battery 1. FIG. 3 is a side view showing the components of FIG. 2. FIG. 4 is a perspective view showing a cross section of components around the positive terminal 410 of the battery 1. FIG. 5 is a side view showing the components of FIG. 4. FIG. 6 is a perspective view showing a partially exploded view of the battery 1. FIG. 7 is a perspective view showing a charging / discharging body 100 of the battery 1. FIG. 8 is a side view showing a cross section of a portion of the charging / discharging body 100 of FIG. 7. FIG. 9 is a side view showing a cross section of a portion of a charging / discharging body 1100 according to a modified example. FIG. 10 is an exploded perspective view showing components around the negative terminal 420 of the battery 1.

[0013] FIG. 11 is an exploded perspective view showing components around the positive terminal 410 of the battery 1. FIG. 12 is an exploded perspective view showing components around the safety valve 530 and sealing plug 540 of the battery 1. FIG. 13 is a top view showing the safety valve 530 and lid 520 of FIG. 12. FIG. 14 is a perspective view showing the safety valve 530 and lid 520 of FIG. 13 in cross section along the longitudinal direction X. FIG. 15 is a perspective view showing region 15 of FIG. 14. FIG. 16 is a perspective view showing region 16 of FIG. 14. FIG. 17 is a perspective view showing the safety valve 530 and lid 520 of FIG. 13 in cross section along the lateral direction Y. FIG. 18 is a perspective view showing region 18 of FIG. 17. FIG. 19 is a perspective view showing region 19 of FIG. 17.

[0014] The battery 1 includes a charging / discharging body 100 that charges and discharges electricity, a current collector 200 connected to the charging / discharging body 100, a current interrupting body 300 connected to the current collector 200, and an electrode terminal 400 connected to the current collector 200 or the current interrupting body 300. The battery 1 also includes a housing 500 in which the components of the battery 1 are housed or attached, an insulator 600 that insulates the components of the battery 1 from the housing 500, and a sealing body 700 that seals the components of the battery 1 from the housing 500.

[0015] The charge / discharge unit 100 charges and discharges electricity. The charge / discharge unit 100 shown in Figures 2 to 8 includes a positive electrode 110, a negative electrode 120, a separator 130, and an electrolyte 140. The charge / discharge unit 100 is configured by winding components, in which the positive electrode 110, the separator 130, the negative electrode 120, and the separator 130 are stacked in this order, into a rectangular parallelepiped shape. The charge / discharge unit 100 may be configured by winding or stacking.

[0016] The positive electrode 110 includes a long positive electrode current collecting layer 111 and a positive electrode active material layer 112 bonded to both sides of the positive electrode current collecting layer 111. The positive electrode current collecting layer 111 includes a current collecting portion 111a and a positive electrode tab 111b. The positive electrode active material layer 112 is bonded to the current collecting portion 111a. As shown in FIG. 8 , the positive electrode active material layer 112 faces, for example, the entire region along the short side direction of the current collecting portion 111a. The positive electrode tab 111b protrudes in the short side direction of the current collecting portion 111a from a side edge 111c along the longitudinal direction of the current collecting portion 111a. The positive electrode tab 111b is formed integrally with the current collecting portion 111a. A plurality of positive electrode tabs 111b are formed on one current collecting portion 111a. The positive electrode 110 may have a configuration in which a positive electrode active material layer 112 is bonded to only one surface of a positive electrode current collecting layer 111. The positive electrode current collecting layer 111 is formed of, for example, aluminum or an aluminum alloy. The positive electrode active material layer 112 contains a positive electrode active material formed of a lithium-containing composite oxide, a binder, a conductive additive, and the like. The lithium-containing composite oxide contains, for example, a metal element such as nickel (Ni), cobalt (Co), or manganese (Mn), and lithium (Li).

[0017] The negative electrode 120 includes a long negative electrode current collecting layer 121 and a negative electrode active material layer 122 bonded to both sides of the negative electrode current collecting layer 121. The negative electrode current collecting layer 121 includes a current collecting portion 121a and a negative electrode tab 121b. As shown in FIG. 8 , the current collecting portion 121a of the negative electrode 120 has a width along the short side greater than that of the current collecting portion 111a of the positive electrode 110. Both ends of the current collecting portion 111a of the positive electrode 110 along the short side are located within the range along the short side of the current collecting portion 121a of the negative electrode 120, with a separator 130 interposed therebetween. The negative electrode active material layer 122 is bonded to the current collecting portion 121a. The negative electrode active material layer 122 faces, for example, the entire area along the short side of the current collecting portion 121a. The negative electrode tab 121b protrudes in the widthwise direction of the current collecting portion 121a from a side edge 121c along the longitudinal direction of the current collecting portion 121a. When stacked with the positive electrode 110 via the separator 130, the negative electrode tab 121b protrudes in the same direction as the positive electrode tab 111b of the positive electrode 110. When stacked with the positive electrode 110 via the separator 130, the negative electrode tab 121b is separated from the positive electrode tab 111b of the positive electrode 110. The negative electrode tab 121b is formed integrally with the current collecting portion 121a. A plurality of negative electrode tabs 121b are formed on one current collecting portion 121a. The negative electrode 120 may be configured such that the negative electrode active material layer 122 is bonded to only one surface of the negative electrode current collecting layer 121. The negative electrode current collecting layer 121 is formed of, for example, copper or a copper alloy. The negative electrode active material layer 122 contains a negative electrode active material made of a carbon-based material, a binder, a conductive additive, etc. The carbon-based material is, for example, graphite.

[0018] The separator 130 allows lithium ions to pass through while insulating the positive electrode 110 and the negative electrode 120. The separator 130 is formed in an elongated shape. As shown in FIG. 8 , the separator 130 has a width along its short side greater than the current collector 111a of the positive electrode 110 and the current collector 121a of the negative electrode 120. Both ends of the current collector 111a of the positive electrode 110 along the short side are located within the range along the short side of the separator 130, and both ends of the current collector 121a of the negative electrode 120 along the short side are located within the range along the short side of the separator 130. The separator 130 is made of a porous material. Polyethylene (PE) or polypropylene (PP) is used for the separator 130. An insulating member may be used instead of the separator 130. The insulating member may be provided on the positive electrode 110 on the side facing the negative electrode 120. The insulating member may be provided on the side facing the positive electrode 110 on the negative electrode 120. The insulating member may be heat resistant. In such a configuration, the separator 130 is not essential.

[0019] The electrolyte 140 allows lithium ions to circulate between the positive electrode 110 and the negative electrode 120. The electrolyte 140 is also called an electrolytic solution. The electrolyte 140 contains a solvent and a solute. The electrolyte 140 may contain an additive. The solvent contains, for example, an organic solvent. The organic solvent is, for example, a carbonate ester such as ethylene carbonate. The solute contains, for example, a lithium salt. The lithium salt is, for example, lithium hexafluorophosphate (LiPF ６ ) is used.

[0020] A charging / discharging body 1100, which is a modified example of the charging / discharging body 100, will be described with reference to FIG. 9 . The configuration of the positive electrode 1110 of the charging / discharging body 1100 is different from the configuration of the positive electrode 110 of the charging / discharging body 100. In the configuration of the charging / discharging body 1100, the same components as those of the charging / discharging body 100 are given the same reference numerals, and their description will be omitted. The positive electrode active material layer 1112 of the charging / discharging body 1100 faces the current collecting part 111a except for both ends along the short side. The heat-resistant insulating layer 1113 of the charging / discharging body 1100 is joined to both ends along the short side of the current collecting part 111a and to the base end portion of the positive electrode tab 111b.

[0021] The current collector 200 is connected to the charge / discharge element 100. The current collector 200 is also called a current collector plate. The current collector 200 shown in Figures 2 to 5, 10, and 11 includes a positive electrode current collector plate 210 and a negative electrode current collector plate 220.

[0022] The positive current collector plate 210 electrically connects the positive electrode tab 111b of the charge / discharge unit 100 to the positive electrode terminal 410 via the current interrupter 300. The positive current collector plate 210 includes a first base portion 210a in the shape of a rectangular parallelepiped plate, a second base portion 210b in the shape of a rectangular parallelepiped plate, and a connecting portion 210c that connects the first base portion 210a and the second base portion 210b in a stepped manner with different heights. A recess 210d is formed on the upper surface of the second base portion 210b, which reduces the thickness of the second base portion 210b. A fragile portion 210e is formed in the center of the recess 210d, which is a ring-shaped depression that partially weakens the recess 210d. The positive current collector plate 210 is made of, for example, aluminum or an aluminum alloy.

[0023] The negative electrode current collector 220 electrically connects the negative electrode tab 121b of the charge / discharge body 100 to the negative electrode terminal 420. The negative electrode current collector 220 includes a rectangular parallelepiped base 220a and an insertion hole 220b penetrating the base 220a. The insertion hole 220b of the negative electrode current collector 220 is inserted into the insertion hole 220b of the negative electrode current collector 220. The negative electrode current collector 220 is formed of, for example, copper or a copper alloy.

[0024] When the internal pressure of the battery 1 is within a predetermined value, the current interrupter 300 remains joined to the positive current collector 210, maintaining the current path between the current collector 200 and the positive terminal 410. On the other hand, when the internal pressure of the battery 1 rises above a predetermined value, the current interrupter 300 separates from the positive current collector 210, thereby opening the current path between the current collector 200 and the positive terminal 410 and interrupting the current path between the current collector 200 and the positive terminal 410. The current interrupter 300 is also referred to as a current interrupting device (CID). The current interrupter 300 is not an essential component of the battery 1. The current interrupter 300 shown in FIGS. 4, 5, and 11 includes a diaphragm 310, a conductive member 320, and a pair of supports 330.

[0025] The diaphragm 310 includes a curved cylindrical main body 310a, a disk-shaped first joint 310b provided at the tip end of the main body 310a, and a ring-shaped second joint 310c provided at the base end of the main body 310a. The first joint 310b is joined to the recess 210d of the positive current collector 210. The second joint 310c is joined to the conductive member 320. When the internal pressure of the battery 1 exceeds a predetermined value, the first joint 310b of the diaphragm 310, together with the recess 210d of the positive current collector 210, deforms toward the outside of the battery 1 and ruptures. As a result, the diaphragm 310 separates from the positive current collector 210. This interrupts the current path between the current collector 200 and the positive terminal 410. The diaphragm 310 is formed of, for example, aluminum or an aluminum alloy.

[0026] The conductive member 320 is formed in a cylindrical shape. The conductive member 320 includes a disk-shaped base 320a and an insertion hole 320b that opens in the center of the base 320a. The positive electrode side insulating plate 620 is joined to the upper surface of the conductive member 320. The second joint portion 310c of the diaphragm 310 is joined to the outer edge of the lower surface of the conductive member 320. The conductive member 320 is formed of, for example, aluminum or an aluminum alloy.

[0027] The support base 330 includes a rectangular parallelepiped main body 330a extending in the short direction of the battery 1, and leg portions 330b extending downward from both longitudinal sides of the main body 330a. One support base 330 is provided on each end of the diaphragm 310 along the longitudinal direction of the battery 1. The main body 330a is attached to the positive electrode side insulating plate 620. The leg portions 330b are attached to the second base portion 210b of the positive electrode current collector plate 210. The support base 330 is formed, for example, from insulating resin.

[0028] The plug 340 is provided in the through-hole 410d of the positive terminal 410. The plug 340 detaches from the through-hole 410d when the internal pressure of the battery 1 increases. Specifically, when the diaphragm 310 deforms toward the outside of the battery 1 and the pressure in the space between the diaphragm 310 and the positive terminal 410 increases, the plug 340 is expelled from the through-hole 410d of the positive terminal 410 toward the outside of the battery. The plug 340 is made of resin and is molded into the through-hole 410d of the positive terminal 410.

[0029] The electrode terminal 400 is connected to the current collector 200 or the current interrupter 300. The electrode terminal 400 shown in Figures 1 to 6, 10, and 11 includes a positive electrode terminal 410 and a negative electrode terminal 420.

[0030] The positive electrode terminal 410 is connected to the conductive member 320 of the current interrupter 300, as shown in Fig. 5, for example. As shown in Figs. 4, 5, and 11, the positive electrode terminal 410 includes a rectangular plate-shaped base 410a, a cylindrical insertion portion 410b that protrudes downward in Fig. 4 from the base 410a, and a cylindrical joint portion 410c that protrudes downward in Fig. 4 from the outer periphery of the base 410a. The positive electrode terminal 410 includes a penetration portion 410d that penetrates the base 410a and the insertion portion 410b. The base 410a is in contact with the base 720a of the positive electrode-side second gasket 720. The insertion portion 410b is inserted into the insertion hole 720b of the positive electrode-side second gasket 720, the positive electrode insertion hole 520c of the lid 520, the insertion hole 620b of the positive electrode-side insulating plate 620, and the insertion hole 320b of the conductive member 320. As shown in FIGS. 5 and 11 , the joint portion 410c protrudes downward from the insertion hole 320b of the conductive member 320 and is expanded radially outward to be joined to the conductive member 320. That is, the joint portion 410c is crimped to the conductive member 320. Furthermore, the joint portion 410c is welded to the conductive member 320. The plug 340 of the current interrupter 300 is inserted into the through portion 410d. In this configuration, the bus bar joined to the positive electrode terminal 410 is provided with a through hole that prevents interference with the plug 340. Alternatively, in such a configuration, the bus bar joined to the positive terminal 410 is positioned to prevent interference with the plug 340. On the other hand, if the battery 1 is not provided with a current interrupter 300, there is no need to provide the through-hole 410d in the positive terminal 410. In other words, if the battery 1 is not provided with a current interrupter 300, the bus bar joined to the positive terminal 410 does not need to have a through-hole. The positive terminal 410 is formed, for example, from aluminum or an aluminum alloy.

[0031] The negative electrode terminal 420 is connected to the negative electrode current collector plate 220, as shown in Fig. 3, for example. As shown in Figs. 3 and 10, the negative electrode terminal 420 includes a rectangular parallelepiped base portion 420a, a cylindrical insertion portion 420b protruding downward in Fig. 3 from the base portion 420a, and a cylindrical joint portion 420c protruding downward in Fig. 3 from the outer periphery of the base portion 420a. The base portion 420a is in contact with a base portion 740a of the negative electrode side second gasket 740. The insertion portion 420b is inserted into the insertion hole 740b of the negative electrode side second gasket 740, the negative electrode insertion hole 520d of the lid 520, the insertion hole 630b of the negative electrode side insulating plate 630, and the insertion hole 220b of the negative electrode current collector plate 220. 3 and 10 , the joint portion 420c protrudes downward from the insertion hole 220b of the negative current collector plate 220 and is expanded radially outward to be joined to the negative current collector plate 220. That is, the joint portion 420c is crimped to the negative current collector plate 220. Furthermore, the joint portion 420c is welded to the negative current collector plate 220. The negative terminal 420 is formed of, for example, copper or a copper alloy.

[0032] The components of the battery 1 are housed or attached in the housing 500. The housing 500 shown in Figures 1 to 6 and 10 to 19 includes a container 510, a lid 520, a safety valve 530, and a sealing plug 540.

[0033] (Configuration of Container 510 (Exterior Body) of the Embodiment) The configuration of the container 510 (exterior body) of the embodiment will be described with reference to FIGS. 2, 4, and 6. FIG.

[0034] The container 510 is an exterior body. As shown in FIGS. 2 and 4 , the container 510 accommodates the charge / discharge unit 100 and the like together with the lid 520. As shown in FIG. 6 , the container 510 extends along the longitudinal direction X (first direction). The container 510 is formed in a rectangular parallelepiped shape. As shown in FIG. 6 , the container 510 includes an opening 510 a and a storage portion 510 b. As shown in FIG. 6 , the opening 510 a opens at the upper end of the container 510 along the longitudinal direction X and the lateral direction Y. The storage portion 510 b is recessed in the container 510 downward in the height direction Z from the opening 510 a. The container 510 is made of, for example, aluminum or an aluminum alloy. A safety valve 530 may be provided in the container 510.

[0035] (Configuration of the Lid 520 (Exterior Body) of the Embodiment) The configuration of the lid 520 (exterior body) of the embodiment will be described with reference to FIGS. 2 to 6 and 10 to 13. FIG.

[0036] The lid 520 is an exterior body. As shown in FIGS. 2 and 4 , the lid 520 accommodates the charge / discharge unit 100 and the like together with the container 510. As shown in FIG. 6 , the lid 520 extends along the longitudinal direction X. The lid 520 seals the opening 510a of the container 510 shown in FIG. 6 . The lid 520 is formed in a rectangular shape along the longitudinal direction X. As shown in FIGS. 10 to 12 , the lid 520 includes a positive electrode insertion hole 520c, a negative electrode insertion hole 520d, a liquid injection insertion hole 520e, and a recess 520f. The lid 520 is made of, for example, aluminum or an aluminum alloy.

[0037] As shown in Fig. 11 , the positive electrode insertion hole 520c is formed on one end side of the lid 520 in the longitudinal direction X. The positive electrode insertion hole 520c is a circular through-hole. The positive electrode insertion hole 520c penetrates from the front surface 520a to the back surface 520b of the lid 520 along the height direction Z. As shown in Fig. 5 , the insertion portion 410b of the positive electrode terminal 410 and the first positive electrode-side gasket 710 of the sealing body 700 are inserted into the positive electrode insertion hole 520c.

[0038] As shown in FIG. 10 , the negative electrode insertion hole 520d is formed on the other end side along the longitudinal direction X of the lid 520. The negative electrode insertion hole 520d faces the positive electrode insertion hole 520c along the longitudinal direction X of the lid 520. The negative electrode insertion hole 520d is a circular through-hole. The negative electrode insertion hole 520d penetrates from the front surface 520a to the back surface 520b of the lid 520 along the height direction Z. As shown in FIG. 3 , the insertion portion 420b of the negative electrode terminal 420 and the negative electrode-side first gasket 730 of the sealing body 700 are inserted into the negative electrode insertion hole 520d.

[0039] As shown in Fig. 12, the liquid injection insertion hole 520e is formed in the lid 520. The liquid injection insertion hole 520e is formed along the longitudinal direction X of the lid 520, between the positive electrode insertion hole 520c and the negative electrode insertion hole 520d. The liquid injection insertion hole 520e is a circular through-hole. The liquid injection insertion hole 520e penetrates from the front surface 520a to the back surface 520b of the lid 520 along the height direction Z. An insertion portion 540b of a sealing plug 540 is inserted into and welded to the negative electrode insertion hole 520d.

[0040] As shown in Figures 1 and 12, the recess 520f is formed in the center of the lid 520 in the longitudinal direction X. As shown in Figures 14 and 17, the recess 520f is recessed from the front surface 520a and the back surface 520b of the lid 520. As shown in Figures 13 to 19, the recess 520f has a first inner edge 520f1, a second inner edge 520f2, a third inner edge 520f3, and a fourth inner edge 520f4.

[0041] The first inner edge 520f1 is formed linearly along the longitudinal direction X (first direction) on one side of the lateral direction Y (second direction) of the recess 520f. The lateral direction Y is a direction intersecting the longitudinal direction X. In the embodiment, the lateral direction Y is a direction perpendicular to the longitudinal direction X. The first inner edge 520f1 is formed in a rectangular shape in the recess 520f extending along the longitudinal direction X and the height direction Z. The first inner edge 520f1 is formed relatively elongated along the longitudinal direction X.

[0042] The second inner edge 520f2 is formed linearly along the longitudinal direction X (first direction) on the other side of the recess 520f in the lateral direction Y. The second inner edge 520f2 faces the first inner edge 520f1 along the lateral direction Y in the recess 520f. The second inner edge 520f2 is formed in a rectangular shape extending along the longitudinal direction X and the height direction Z in the recess 520f. The second inner edge 520f2 is formed relatively elongated along the longitudinal direction X.

[0043] The third inner edge 520f3 is continuous with the first inner edge 520f1 and the second inner edge 520f2 in the recess 520f. The third inner edge 520f3 is formed in an arc shape along the short-side direction Y. The third inner edge 520f3 is formed in a curved rectangular shape along the short-side direction Y and the height direction Z. The third inner edge 520f3 is formed to be relatively elongated along the short-side direction Y.

[0044] The fourth inner edge 520f4 faces the third inner edge 520f3 in the longitudinal direction X in the recess 520f. The fourth inner edge 520f4 is continuous with the first inner edge 520f1 and the second inner edge 520f2 in the recess 520f. The fourth inner edge 520f4 is formed in an arc shape along the short-side direction Y. The fourth inner edge 520f4 is formed in a curved rectangular shape along the short-side direction Y and the height direction Z. The fourth inner edge 520f4 is formed to be relatively elongated along the short-side direction Y.

[0045] (Configuration of Safety Valve 530 of the Embodiment) The configuration of the safety valve 530 of the embodiment will be described with reference to FIGS. 12 to 19. FIG.

[0046] The safety valve 530 ruptures outward from the battery 1 when the internal pressure of the battery 1 reaches a predetermined value, thereby reducing or equalizing the internal pressure of the battery 1 to atmospheric pressure. The safety valve 530 corresponds to a rupture valve. As shown in FIG. 12 , the safety valve 530 is provided on the lid 520. The safety valve 530 is formed integrally with the lid 520. That is, like the lid 520, the safety valve 530 is made of, for example, aluminum or an aluminum alloy. The safety valve 530 may be formed together with an outer frame that supports the safety valve 530 in an annular shape, and the outer frame may be inserted and joined into a through-hole formed in the safety valve 530. The safety valve 530 may be inserted and joined into a through-hole formed in the lid 520. The safety valve 530 may also be provided on the container 510.

[0047] As shown in Fig. 13 , the safety valve 530 includes a central portion 531, one end portion 532, and the other end portion 533. As shown in Figs. 14 to 19 , the central portion 531, the one end portion 532, and the other end portion 533 are convexly curved in a direction away from the charge / discharge body 100. The direction away from the charge / discharge body 100 is upward in the height direction Z shown in Fig. 12 . The one end portion 532 and the other end portion 533 are formed in a symmetrical shape along the longitudinal direction X with respect to the central portion 531.

[0048] As shown in Fig. 13, the central portion 531 is formed in a rectangular shape in the recess 520f of the lid 520. The length d of the central portion 531 along the longitudinal direction X from one end 531p to the other end 531q is set to 1 mm or more. By setting it in this manner, the safety valve 530 is provided with a rectangular portion in addition to a pair of arc-shaped portions. As shown in Figs. 14 and 17, the central portion 531 extends along the longitudinal direction X and the lateral direction Y inside the recess 520f.

[0049] As shown in Figures 17 and 19, the central portion 531 includes a first groove 531a formed in a straight line. The first groove 531a is a recess with a rectangular cross section that opens to the front side of the lid 520. The first groove 531a is adjacent to the first inner edge 520f1 of the lid 520 in the central portion 531. The first groove 531a is formed in a recessed shape along the first inner edge 520f1 of the lid 520, spaced apart from the first inner edge 520f1. The recessed portion of the first groove 531a is exposed to the outside of the battery 1.

[0050] As shown in Figures 17 and 18, the central portion 531 includes a second groove 531b formed in a straight line. The second groove 531b is a recess with a rectangular cross section that opens to the front side of the lid 520. The second groove 531b is adjacent to the second inner edge 520f2 of the lid 520 in the central portion 531. The second groove 531b is formed in a recessed shape along the second inner edge 520f2 of the lid 520, spaced apart from the second inner edge 520f2. The recessed portion of the second groove 531b is exposed to the outside of the battery 1.

[0051] As shown in Fig. 13, the one end 532 is continuous with one end 531p of the central portion 531 in the recess 520f of the lid 520. The one end 532 is formed in an arc shape on the side of the one end 531p of the central portion 531 along the longitudinal direction X. The one end 532 is formed in a semicircular shape with a diameter φ. As shown in Figs. 14 and 17, the one end 532 extends along the longitudinal direction X and the lateral direction Y inside the recess 520f.

[0052] As shown in FIGS. 14 and 15 , the one end 532 includes a third groove 532c formed in an arc shape. The third groove 532c is a recess with a rectangular cross section that opens to the front side of the lid 520. The third groove 532c is continuous with the first groove 531a and the second groove 531b. The third groove 532c is adjacent to the third inner edge 520f3 of the lid 520 at the one end 532. The third groove 532c is formed in a recessed shape along the third inner edge 520f3 of the lid 520 at the one end 532, spaced apart from the third inner edge 520f3. The recessed portion of the third groove 532c is exposed to the outside of the battery 1.

[0053] As shown in Fig. 13, the other end 533 is continuous with the other end 531q of the central portion 531 in the recess 520f of the lid 520. The other end 533 is formed in an arc shape on the side of the other end 531q of the central portion 531 along the longitudinal direction X. The other end 533 is formed in a semicircular shape with a diameter φ. As shown in Fig. 14, the other end 533 extends along the longitudinal direction X and the lateral direction Y inside the recess 520f.

[0054] As shown in FIGS. 14 and 16 , the other end 533 includes a fourth groove 533d formed in an arc shape. The fourth groove 533d is a recessed portion with a rectangular cross section that opens to the front side of the lid 520. The fourth groove 533d is continuous with the first groove 531a and the second groove 531b. The fourth groove 533d is adjacent to the fourth inner edge 520f4 of the lid 520 at the other end 533. The fourth groove 533d is formed in a recessed shape along the fourth inner edge 520f4 of the lid 520 at the other end 533, spaced apart from the fourth inner edge 520f4. The recessed portion of the fourth groove 533d is exposed to the outside of the battery 1.

[0055] As shown in FIG. 14 , the safety valve 530 has a central portion 531, one end portion 532, and the other end portion 533 formed in a thin plate shape along the longitudinal direction X and the lateral direction Y. The central portion 531, one end portion 532, and the other end portion 533 are recessed from the front surface 520 a side and the back surface 520 b side of the lid 520 along the height direction Z. That is, the central portion 531, one end portion 532, and the other end portion 533 are thinner than the lid 520. The central portion 531, one end portion 532, and the other end portion 533 have the same thickness along the height direction Z. As shown in FIG. 14 , the length of the central portion 531, one end portion 532, and the other end portion 533 recessed from the front surface 520 a side of the lid 520 is relatively longer than the length of the central portion 531, one end portion 532, and the other end portion 533 recessed from the back surface 520 b side of the lid 520.

[0056] In the safety valve 530, the thickness of the first groove 531a is greater than the thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d. The first groove 531a has a uniform thickness from one end, which is the boundary with the third groove 532c, to the other end, which is the boundary with the fourth groove 533d. The second groove 531b, the third groove 532c, and the fourth groove 533d have a uniform thickness from the end of the third groove 532c, which is the boundary with the first groove 531a, to the end of the fourth groove 533d, which is the boundary with the first groove 531a. Here, the groove thickness refers to the thickness of the bottom of the concave groove. In other words, the groove thickness corresponds to the dimension in the height direction Z from the bottom of the groove to the back surface of the safety valve 530. In the safety valve 530, the thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d are set to be 0.2 times or more and 0.7 times or less the thickness of the first groove 531a. The thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d are, for example, 80 μm or 120 μm. The thickness of the first groove 531a is, for example, 200 μm.

[0057] As shown in Fig. 6, the sealing plug 540 seals the liquid injection insertion hole 520e of the lid 520. The sealing plug 540 is formed in a cylindrical shape. As shown in Fig. 12, the sealing plug 540 includes a head portion 540a having a relatively large outer diameter and an insertion portion 540b that is continuous with the head portion 540a and has a relatively small outer diameter. The head portion 540a of the sealing plug 540 is welded to the lid 520. The insertion portion 540b is inserted into the liquid injection insertion hole 520e. The sealing plug 540 is formed of, for example, aluminum or an aluminum alloy.

[0058] The insulator 600 insulates the components of the battery 1 from the housing 500. The insulator 600 shown in Figures 2 to 5, 10 and 11 includes an insulating cover 610, a positive electrode side insulating plate 620, and a negative electrode side insulating plate 630.

[0059] The insulating cover 610 covers the charging / discharging unit 100. The insulating cover 610 exposes one side 100a of the charging / discharging unit 100 to the outside and covers the rest of the charging / discharging unit 100 except for the side 100a. The insulating cover 610 is formed, for example, in a pentahedral shape and folded into a box shape. The insulating cover 610 is formed, for example, from polypropylene.

[0060] The positive electrode side insulating plate 620 insulates the positive electrode current collector plate 210 and the conductive member 320 from the lid 520. The positive electrode side insulating plate 620 includes a rectangular parallelepiped base 620a, an insertion hole 620b penetrating the base 620a, and a protrusion 620c annularly extending from the side edge of the base 620a and protruding in a direction away from the surrounding lid 520. The positive electrode side insulating plate 620 accommodates the positive electrode current collector plate 210, the conductive member 320, and the like in a space defined by the base 620a and the protrusion 620c. The insertion portion 410b of the positive electrode terminal 410 is inserted into the insertion hole 620b. The positive electrode side insulating plate 620 is formed, for example, from insulating resin.

[0061] The negative electrode side insulating plate 630 insulates the negative electrode current collector plate 220 from the lid 520. The negative electrode side insulating plate 630 includes a rectangular parallelepiped base 630a, an insertion hole 630b penetrating the base 630a, and a protrusion 630c that annularly protrudes from the side edge of the base 630a in a direction away from the surrounding lid 520. The negative electrode side insulating plate 630 accommodates the negative electrode current collector plate 220 in a space defined by the base 630a and the protrusion 630c. The insertion portion 420b of the negative electrode terminal 420 is inserted into the insertion hole 630b. The negative electrode side insulating plate 630 is formed, for example, from insulating resin.

[0062] The sealing body 700 seals the components of the battery 1 and the housing 500. The sealing body 700 shown in Figures 2 to 5, 10, and 11 includes a positive electrode side first gasket 710, a positive electrode side second gasket 720, a negative electrode side first gasket 730, and a negative electrode side second gasket 740.

[0063] The positive electrode side first gasket 710 seals the positive electrode current collector plate 210 and the lid 520, thereby sealing the housing 500. The positive electrode side first gasket 710 is formed in a cylindrical shape. As shown in FIG. 11 , the positive electrode side first gasket 710 includes a first insertion portion 710a having a relatively large outer diameter, a second insertion portion 710b continuous with the first insertion portion 710a and having a relatively small outer diameter, and an insertion hole 710c passing through the first insertion portion 710a and the second insertion portion 710b. As shown in FIG. 5 , the positive electrode side first gasket 710 is provided between the positive electrode terminal 410 and the positive electrode current collector plate 210. The first insertion portion 710a is inserted into the insertion hole 620b of the positive electrode side insulating plate 620 shown in FIG. 11 . The second insertion portion 710b is inserted into the positive electrode insertion hole 520c of the lid 520 and the insertion hole 720b of the positive electrode-side second gasket 720 shown in Fig. 11. The insertion portion 410b of the positive electrode terminal 410 shown in Fig. 11 is inserted into the insertion hole 710c. The positive electrode-side first gasket 710 is formed, for example, from rubber that is insulating and elastic.

[0064] The positive electrode side second gasket 720 seals the positive electrode terminal 410 and the lid 520. As shown in FIG. 11 , the positive electrode side second gasket 720 includes a rectangular parallelepiped plate-shaped base 720a, an insertion hole 720b penetrating the base 720a, and a protrusion 720c that annularly protrudes from the side edge of the base 720a in a direction away from the surrounding lid 520. The positive electrode side second gasket 720 accommodates the positive electrode terminal 410 in a space defined by the base 720a and the protrusion 720c. The insertion portion 410b of the positive electrode terminal 410 is inserted into the insertion hole 720b. The positive electrode side second gasket 720 is formed, for example, from an insulating resin.

[0065] The negative electrode side first gasket 730 seals the negative electrode current collector plate 220 and the lid 520, thereby sealing the housing 500. The negative electrode side first gasket 730 is formed in a cylindrical shape. As shown in FIG. 10 , the negative electrode side first gasket 730 includes a first insertion portion 730a having a relatively large outer diameter, a second insertion portion 730b continuous with the first insertion portion 730a and having a relatively small outer diameter, and an insertion hole 730c penetrating the first insertion portion 730a and the second insertion portion 730b. As shown in FIG. 3 , the negative electrode side first gasket 730 is provided between the second member 422 of the negative electrode terminal 420 and the negative electrode current collector plate 220. The first insertion portion 730a is inserted into the insertion hole 630b of the negative electrode side insulating plate 630 shown in FIG. 10 . The second insertion portion 730b is inserted into the negative electrode insertion hole 520d of the lid 520 and the insertion hole 740b of the negative electrode-side second gasket 740 shown in Fig. 10. The main body portion 421b of the first member 421 of the negative electrode terminal 420 shown in Fig. 10 is inserted into the insertion hole 730c. The negative electrode-side first gasket 730 is formed, for example, from rubber that is insulating and elastic.

[0066] The negative electrode side second gasket 740 seals the negative electrode terminal 420 and the lid 520. As shown in FIG. 10 , the negative electrode side second gasket 740 includes a rectangular parallelepiped plate-shaped base 740a, an insertion hole 740b penetrating the base 740a, and a protrusion 740c that annularly protrudes from the side edge of the base 740a in a direction away from the surrounding lid 520. The negative electrode side second gasket 740 accommodates the negative electrode terminal 420 in a space defined by the base 740a and the protrusion 740c. The insertion portion 420b of the negative electrode terminal 420 is inserted into the insertion hole 740b. The negative electrode side second gasket 740 is formed, for example, from an insulating resin.

[0067] (Basis of Simulation of Safety Valve 530 of the Embodiment) The basis of the simulation of the safety valve 530 of the embodiment will be described with reference to Equations 1 to 6, FIGS. 20 and 21. FIG.

[0068] Fig. 20 is a schematic diagram showing the relationship between the rupture pressure: P of safety valve 530 and the thickness: t of second groove 531b, third groove 532b, and fourth groove 533d of safety valve 530. Fig. 21 is a schematic diagram showing the relationship between the force applied to first groove 531a of safety valve 530 and the elongation of first groove 531a of safety valve 530.

[0069] The simulation of the safety valve 530 of the embodiment was carried out based on the following calculation formula.

[0070]

[0071] In equation 1, S represents the area of ​​the safety valve 530. The safety valve 530 is curved convexly along the height direction Z toward the side away from the charging / discharging body 100. In equation 1, the area of ​​the safety valve 530 is approximated to the area in a plane formed by the longitudinal direction X and the lateral direction Y. In equation 1, the area of ​​the safety valve 530 is the sum of the area of ​​the central portion 531, the area of ​​one end portion 532, and the area of ​​the other end portion 533. The central portion 531 is rectangular. The area of ​​the central portion 531 is expressed by d×2r. That is, the area of ​​the central portion 531 is expressed by d×Φ. The one end portion 532 and the other end portion 533 are each semicircular. The area of ​​the one end portion 532 and the area of ​​the other end portion 533 are each expressed by (π×r ２That is, the area of ​​one end 532 and the area of ​​the other end 533 are expressed by (π×(Φ / 2) ２ ) / 2. As a result, the area of ​​the safety valve 530 is expressed as d×Φ+π×(Φ / 2) ２ is expressed by

[0072]

[0073] In Equation 2, F represents the force acting on the safety valve 530 immediately before it ruptures due to the internal pressure of the battery 1 received from the charging / discharging body 100 side. F is defined by S × P. P is the rupture pressure of the safety valve 530 shown in FIG. 20. P is defined by α × t. That is, F = S × α × t. α is a first coefficient. α is a value that reflects the rigidity of the groove that ruptures the safety valve 530. t is the thickness of the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530.

[0074]

[0075] F' in Equation 3 represents the force exerted on the safety valve 530 immediately after rupture due to the internal pressure of the battery 1 received from the charging / discharging unit 100. F' is defined as β × F. β is a second coefficient. β is a predetermined value reflecting the state in which the safety valve 530 receives pressure from the charging / discharging unit 100 when the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 are separated from the recess 520f of the lid 520 and the first groove 531a remains in the recess 520f of the lid 520. When only the first groove 531a remains in the lid 520, the safety valve 530 receives the internal pressure of the battery 1 from the charging / discharging unit 100 through the area represented by S in Equation 1. β is a value less than 1 and greater than 0.

[0076]

[0077] In Equation 4, σ represents the shear force acting on the first groove 531a of the safety valve 530 due to the internal pressure of the battery 1 received from the charging / discharging unit 100 side. σ is defined by F' / (t'×d). t' is the thickness of the first groove 531a that remains in the recess 520f of the lid 520 when the safety valve 530 is torn open. d is the length of the first groove 531a along the longitudinal direction X.

[0078]

[0079] Equation 5 expresses the conditions under which the safety valve 530 remains on the lid 520 and the conditions under which the safety valve 530 stands up from the lid 520. The minimum value σ of the plastic deformation of the safety valve 530 ｍｉｎ is defined by the elastic limit × 0.7 shown in FIG. 21. The condition for plastic deformation of the safety valve 530 is σ ｍｉｎ The condition under which the safety valve 530 stands up from the lid 520 corresponds to the condition under which the first groove 531a of the safety valve 530 is plastically deformed in the recess 520f of the lid 520. The maximum value of the shear force of the safety valve 530, σ ｍａｘ is defined by the tensile stress×0.7 shown in FIG. 21. The condition for the safety valve 530 to remain in the lid 520, that is, the condition for the safety valve 530 not to come off the lid 520, is σ<σ ｍａｘ The condition under which the safety valve 530 remains in the lid 520 corresponds to the condition under which the first groove 531 a of the safety valve 530 is not sheared off from the recess 520 f of the lid 520 .

[0080]

[0081] Based on Equation 5, Equation 6 expresses the condition under which the safety valve 530 remains in the lid 520 and the condition under which the safety valve 530 rises from the lid 520, based on the ratio t / t'. Equation 6 is obtained by multiplying each formula in Equation 5 by d / (β×S×α).

[0082] (Verification 1 of the Safety Valve 530 of the Embodiment) Verification 1 of the safety valve 530 of the embodiment will be described with reference to Table 1, FIGS. 22 and 23. FIG.

[0083] Table 1 shows the verification conditions, verification parameters, verification method, and verification results of the simulation regarding the rupture of the safety valve 530.

[0084]

[0085] Fig. 22 is a graph showing the results of simulating the displacement range and displacement amount of the second groove 531b of the safety valve 530 under conditions 1 to 9 in Table 1. Fig. 23 is a graph showing the results of simulating the maximum value of the displacement range of the second groove 531b of the safety valve 530 under conditions 1 to 9 in Table 1.

[0086] The horizontal axis of Fig. 22 represents the length d [mm] of the portion of the second groove 531b in the central portion 531 of the safety valve 530. The vertical axis of Fig. 22 represents the amount of displacement [mm] of the portion of the second groove 531b in the height direction Z in the central portion 531 of the safety valve 530. The amount of displacement of the portion of the second groove 531b in the height direction Z is the length of deformation of the portion of the second groove 531b upward in the height direction Z as a result of the safety valve 530 being subjected to pressure.

[0087] In Table 1, the region in which the safety valve 530 begins to rupture is the region in which the displacement of the second groove 531b of the safety valve 530 is greatest. When the safety valve 530 is subjected to a predetermined pressure, rupture begins, starting from the region in which the displacement of the second groove 531b is greatest. The narrower the region in which the safety valve 530 begins to rupture, the more likely it is that the rupture initiation position will be stable in the center of the second groove 531b and that the position will be determined. As a result, the safety valve 530 is more likely to rupture as specified. On the other hand, the wider the region in which the safety valve 530 begins to rupture, the more likely it is that the rupture initiation position will deviate from the center of the second groove 531b and the position will be unstable. In other words, the wider the region in which the safety valve 530 begins to rupture, the more difficult it is to determine the position in the second groove 531b where rupture begins. In this case, it becomes more difficult for the safety valve 530 to rupture as specified, and there is a risk of the safety valve 530 rupturing partially.

[0088] In the simulation, the outer shape of the safety valve 530 was designed using 3D CAD software, and then the deformation of the safety valve 530 was analyzed using predetermined stress analysis software.

[0089] Under verification condition 1, as shown in Table 1, the length d1 of the central portion 531 is 7 mm, and the diameter φ of the one end 532 and the other end 533 is 14 mm. The diameter φ is determined by assuming that the one end 532 and the other end 533 are semicircular. The ratio of the length d divided by the diameter φ is defined as ratio 1. The ratio 1 under verification condition 1 is 0.5 (7 mm / 14 mm). Under verification condition 1, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 is smallest at both ends of the second groove 531b (0 mm and 7 mm on the horizontal axis) and largest at the center of the second groove 531b (3.5 mm on the horizontal axis). The displacement of the second groove 531b of the safety valve 530 is largest at the center of the second groove 531b (3.5 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 7 mm on the horizontal axis). 22 , under verification condition 1, the region in the second groove 531b where the amount of displacement is greatest is located at the center of the second groove 531b and is an extremely narrow region along the longitudinal direction X. That is, the region in the second groove 531b where the amount of displacement is greatest is configured as a point at the center of the second groove 531b. The region in the second groove 531b where the amount of displacement is greatest corresponds to the region with a pointed upper end in the inverted U-shaped graph for verification condition 1.

[0090] In the embodiment, the extremely narrow region is a region where the displacement amount of the second groove 531b is, for example, within ±1 mm from the center of the second groove 531b along the longitudinal direction X, when the region where the displacement amount of the second groove 531b is the largest is defined as a region where the displacement amount of the second groove 531b is, for example, in the top few percent or more. Defining such a region is one example in the embodiment.

[0091] Under verification condition 1, when pressure exceeding a predetermined value is applied to the safety valve 530, the center of the second groove 531b in the central portion 531 becomes the starting point of rupture, and the rupture of the safety valve 530 progresses evenly and quickly toward both ends of the second groove 531b. That is, the rupture starts from an extremely narrow region in the center of the second groove 531b in the central portion 531, and progresses evenly and quickly toward both ends of the second groove 531b. Furthermore, under verification condition 1, the rupture of the safety valve 530 progresses evenly and quickly from both ends of the central portion 531 toward the third groove 532c of one end portion 532 and the fourth groove 533d of the other end portion 533.

[0092] Under verification condition 2, as shown in Table 1, the length d1 of the central portion 531 was 10.5 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 2 was 0.75 (10.5 mm / 14 mm). Under verification condition 2, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (5.25 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 10.5 mm on the horizontal axis). Under verification condition 2, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was an extremely narrow region along the longitudinal direction X. The region of the second groove 531b with the greatest displacement corresponds to the region with the pointed upper end in the inverted U-shaped graph for verification condition 2.

[0093] Under verification condition 2, when pressure exceeding a predetermined value is applied to safety valve 530, the opening of safety valve 530 starts from an extremely narrow region in the center of second groove 531b in central portion 531, and the opening of safety valve 530 progresses evenly and quickly toward both ends of second groove 531b. Furthermore, under verification condition 2, the opening of safety valve 530 progresses evenly and quickly from both ends of central portion 531 toward third groove 532c at one end 532 and fourth groove 533d at the other end 533.

[0094] Under verification condition 3, as shown in Table 1, the length d1 of the central portion 531 was 14 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 3 was 1.0 (14 mm / 14 mm). Under verification condition 3, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (7 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 14 mm on the horizontal axis). Under verification condition 3, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was an extremely narrow region along the longitudinal direction X. The region of the second groove 531b with the greatest displacement corresponds to the region with the pointed upper end in the inverted U-shaped graph for verification condition 3.

[0095] Under verification condition 3, when pressure exceeding a predetermined value is applied to safety valve 530, the opening of safety valve 530 starts from an extremely narrow region in the center of second groove 531b in central portion 531, and the opening of safety valve 530 progresses evenly and quickly toward both ends of second groove 531b. Furthermore, under verification condition 3, the opening of safety valve 530 progresses evenly and quickly from both ends of central portion 531 toward third groove 532c at one end 532 and fourth groove 533d at the other end 533.

[0096] Under verification condition 4, as shown in Table 1, the length d1 of the central portion 531 was 21 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 4 was 1.5 (21 mm / 14 mm). Under verification condition 4, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (10.5 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 21 mm on the horizontal axis). Under verification condition 4, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was a narrow region along the longitudinal direction X. The region of the second groove 531b with the greatest displacement corresponds to the slightly pointed region at the top of the inverted U-shaped graph for verification condition 4.

[0097] In the embodiment, the narrow region is a region where the displacement amount of the second groove 531b is, for example, within ±2 mm from the center of the second groove 531b along the longitudinal direction X, when the region where the displacement amount of the second groove 531b is the largest is defined as a region where the displacement amount of the second groove 531b is, for example, in the top few percent or more. Defining such a region is one example in the embodiment.

[0098] Under verification condition 4, when pressure exceeding a predetermined value is applied to the safety valve 530, the opening of the safety valve 530 starts from a narrow central region of the second groove 531b in the central portion 531, and progresses toward both ends of the second groove 531b. Furthermore, under verification condition 4, the opening of the safety valve 530 progresses from both ends of the central portion 531 toward the third groove 532c in one end portion 532 and the fourth groove 533d in the other end portion 533.

[0099] Under verification condition 5, as shown in Table 1, the length d1 of the central portion 531 was 28 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 5 was 2.0 (28 mm / 14 mm). Under verification condition 5, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (14 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 28 mm on the horizontal axis). Under verification condition 5, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was a narrow region along the longitudinal direction X. The region of the second groove 531b with the greatest displacement corresponds to the slightly pointed region at the top of the inverted U-shaped graph for verification condition 5.

[0100] Under verification condition 5, when pressure exceeding a predetermined value is applied to safety valve 530, the opening of safety valve 530 starts from a narrow central region of second groove 531b in central portion 531, and progresses toward both ends of second groove 531b. Furthermore, under verification condition 5, the opening of safety valve 530 progresses from both ends of central portion 531 toward third groove 532c at one end 532 and fourth groove 533d at the other end 533.

[0101] Under verification condition 6, as shown in Table 1, the length d1 of the central portion 531 is 35 mm, and the diameter φ of the one end 532 and the other end 533 is 14 mm. The ratio 1 under verification condition 6 is 2.5 (35 mm / 14 mm). Under verification condition 6, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 is greatest at the center of the second groove 531b (17.5 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 35 mm on the horizontal axis). Under verification condition 6, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement is located at the center of the second groove 531b and is a slightly wide region along the longitudinal direction X. The region of the second groove 531b with the greatest displacement corresponds to the slightly flat region at the top of the inverted U-shaped graph for verification condition 6.

[0102] In the embodiment, the somewhat flat region at the upper end refers to a region where the displacement amount of the second groove 531b is within, for example, ±10 mm from the center of the second groove 531b along the longitudinal direction X, when the region where the displacement amount of the second groove 531b is the largest is defined as a region where the displacement amount of the second groove 531b is in the top few percent or more. Defining such a region is one example in the embodiment.

[0103] Under verification condition 6, when pressure exceeding a predetermined value is applied to the safety valve 530, an arbitrary position in a somewhat wide area in the center of the second groove 531b in the central portion 531 becomes the starting point of rupture, and the rupture of the safety valve 530 progresses toward both ends of the second groove 531b. In other words, under verification condition 6, the rupture does not necessarily start from the center of the second groove 531b, but a portion away from the center of the second groove 531b becomes the starting point of rupture, and the rupture of the safety valve 530 may progress unevenly toward both ends of the second groove 531b. Furthermore, under verification condition 6, the rupture of the safety valve 530 progresses from both ends of the central portion 531 toward the third groove 532c of one end portion 532 and the fourth groove 533d of the other end portion 533. There is a possibility that the tearing of the second groove 531b in the central portion 531 will be completed before the tearing of the third groove 532c in the one end portion 532 and the fourth groove 533d in the other end portion 533 begins.

[0104] Under verification condition 7, as shown in Table 1, the length d1 of the central portion 531 was 42 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 7 was 3.0 (42 mm / 14 mm). Under verification condition 7, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (21.0 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 42 mm on the horizontal axis). Under verification condition 7, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was a slightly wide region along the longitudinal direction X. The region of the second groove 531b with the greatest displacement corresponds to the slightly flat region at the top of the inverted U-shaped graph for verification condition 7.

[0105] Under verification condition 7, when pressure exceeding a predetermined value is applied to the safety valve 530, an arbitrary position in a somewhat wide area in the center of the second groove 531b in the central portion 531 becomes the starting point of rupture, and the rupture of the safety valve 530 progresses toward both ends of the second groove 531b. In other words, under verification condition 7, the rupture does not necessarily start from the center of the second groove 531b, but a portion away from the center of the second groove 531b becomes the starting point of rupture, and the rupture of the safety valve 530 may progress unevenly toward both ends of the second groove 531b. Furthermore, under verification condition 7, the rupture of the safety valve 530 progresses from both ends of the central portion 531 toward the third groove 532c of one end portion 532 and the fourth groove 533d of the other end portion 533. There is a possibility that the tearing of the second groove 531b in the central portion 531 will be completed before the tearing of the third groove 532c in the one end portion 532 and the fourth groove 533d in the other end portion 533 begins.

[0106] Under verification condition 8, as shown in Table 1, the length d1 of the central portion 531 was 56 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 8 was 4.0 (56 mm / 14 mm). Under verification condition 8, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (28 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 56 mm on the horizontal axis). Under verification condition 8, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was a wide region along the longitudinal direction X. This wide region corresponds to a linear region, not a dotted region. The region of the second groove 531b with the greatest displacement corresponds to the flat region at the top of the inverted U-shaped graph under verification condition 8.

[0107] In the embodiment, the flat region at the upper end is a region where the displacement amount in the second groove 531b exceeds, for example, ±10 mm from the center of the second groove 531b along the longitudinal direction X, when the region where the displacement amount in the second groove 531b is the largest is defined as a region where the displacement amount in the second groove 531b is in the top few percent or more. Defining such a region is one example in the embodiment.

[0108] Under verification condition 8, when pressure exceeding a predetermined value is applied to the safety valve 530, an arbitrary position in a wide central region of the second groove 531b in the central portion 531 becomes the starting point of rupture, and the rupture of the safety valve 530 progresses toward both ends of the second groove 531b. In other words, under verification condition 8, the rupture does not necessarily start from the center of the second groove 531b, but rather a portion far away from the center of the second groove 531b becomes the starting point of rupture, and the rupture of the safety valve 530 may progress quite unevenly toward both ends of the second groove 531b. Furthermore, under verification condition 8, the rupture of the safety valve 530 progresses from both ends of the central portion 531 toward the third groove 532c of one end 532 and the fourth groove 533d of the other end 533. It is highly likely that the tearing of the second groove 531b in the central portion 531 will be completed before the tearing of the third groove 532c in the one end portion 532 and the fourth groove 533d in the other end portion 533 begins.

[0109] Under verification condition 9, as shown in Table 1, the length d1 of the central portion 531 was 70 mm, and the diameter φ of the one end 532 and the other end 533 was 14 mm. The ratio 1 under verification condition 9 was 5.0 (70 mm / 14 mm). Under verification condition 9, as shown in FIG. 22 , the displacement of the second groove 531b of the safety valve 530 was greatest at the center of the second groove 531b (35 mm on the horizontal axis) and smallest at both ends of the second groove 531b (0 mm and 70 mm on the horizontal axis). Under verification condition 9, as shown in FIG. 22 , the region of the second groove 531b with the greatest displacement was located at the center of the second groove 531b and was a wide region along the longitudinal direction X. This wide region corresponds to a linear region, not a dotted region. The region of the second groove 531b with the greatest displacement corresponds to the flat region at the top of the inverted U-shaped graph under verification condition 9.

[0110] Under verification condition 9, when pressure exceeding a predetermined value is applied to the safety valve 530, an arbitrary position in a wide central region of the second groove 531b in the central portion 531 becomes the starting point of rupture, and the rupture of the safety valve 530 progresses toward both ends of the second groove 531b. In other words, under verification condition 9, the rupture does not necessarily start from the center of the second groove 531b, but a portion far away from the center of the second groove 531b becomes the starting point of rupture, and the rupture of the safety valve 530 may progress quite unevenly toward both ends of the second groove 531b. Furthermore, under verification condition 9, the rupture of the safety valve 530 progresses from both ends of the central portion 531 toward the third groove 532c of one end 532 and the fourth groove 533d of the other end 533. It is highly likely that the tearing of the second groove 531b in the central portion 531 will be completed before the tearing of the third groove 532c in the one end portion 532 and the fourth groove 533d in the other end portion 533 begins.

[0111] Under verification conditions 1 to 9, the ratio 1 of length d / diameter Φ was varied from 0.5 to 5.0. The length d was determined as the length of the second groove 531b in the central portion 531 of the safety valve 530. The diameter Φ was determined as the diameter of the semicircular end portion 532 and the semicircular end portion 533. As shown in FIG. 23 , as the ratio 1 increased from 0.5 to 5.0, the displacement of the second groove 531b in the central portion 531 of the safety valve 530 along the height direction Z increased. The increase in the displacement of the second groove 531b saturated when the ratio 1 was approximately 3.0.

[0112] (Verification 2 of the Safety Valve 530 of the Embodiment) Verification 2 of the safety valve 530 of the embodiment will be described with reference to Table 2 and FIGS. 24 to 27.

[0113] Table 2 shows the verification conditions, verification parameters, verification method, and verification results of the simulation experiment regarding the residual property and upright property of the safety valve 530.

[0114]

[0115] In Table 2, the residual property of the safety valve 530 refers to whether or not the first groove 531a remains in the recess 520f of the lid 520 when the safety valve 530 is torn open. When the safety valve 530 is torn open, it is preferable to suppress or prevent interference between the safety valve 530 and surrounding components. Therefore, it is preferable that the safety valve 530 does not come off the lid 520 when the safety valve 530 is torn open.

[0116] In Table 2, the ability of the safety valve 530 to stand up refers to the ability of the safety valve 530 to bend sufficiently and stand up from the recess 520f of the lid 520 when the safety valve 530 is torn open. If the safety valve 530 is able to bend sufficiently and stand up when the safety valve 530 is torn open, the pressure inside the battery 1 can be quickly reduced.

[0117] In Table 2, there is a trade-off between the residual capacity and the stand-up ability of the safety valve 530. The better the residual capacity of the safety valve 530, the worse the stand-up ability of the safety valve 530. The better the stand-up ability of the safety valve 530, the worse the residual capacity of the safety valve 530.

[0118] Fig. 24 is a photograph showing the experimental results under condition 14 in Table 2. Fig. 25 is a simulation image under condition 14 in Table 2. Fig. 26 is a photograph showing the experimental results under condition 16 in Table 2. Fig. 27 is a simulation image under condition 16 in Table 2.

[0119] In the simulation, the outer shape of the safety valve 530 was designed using 3D CAD software, and then the deformation of the safety valve 530 was analyzed using predetermined stress analysis software.

[0120] Regarding the residual property of the safety valve 530, as shown in Equations 5 and 6 and FIG. 21, the maximum value σ of the shear force in the first groove 531a of the safety valve 530 is ｍａｘ is defined and evaluated by the tensile stress × 0.7 shown in Fig. 21. In the embodiment, the maximum value σmax of the shear force of the safety valve 530, that is, the limit condition for the safety valve 530 to remain in the lid 520, corresponds to t / t' = 0.7. If t / t' exceeds 0.7, the safety valve 530 does not remain in the lid 520 and becomes detached from the lid 520.

[0121] Regarding the uprightness of the safety valve 530, as shown in Equations 5 and 6 and FIG. 21, the minimum value σ of plastic deformation in the first groove 531a of the safety valve 530 is ｍｉｎ is defined as the elastic limit × 0.7 shown in Fig. 21 and evaluated. In this embodiment, the limit condition for the safety valve 530 to rise from the lid 520 corresponds to t / t' = 0.2. If t / t' is less than 0.2, the safety valve 530 will not rise from the lid 520.

[0122] The residual property and rising property of the safety valve 530 are evaluated by calculation based on the formulas 5 and 6, as well as by taking into consideration the experimental results and simulation results.

[0123] Under verification condition 11, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in one end portion 532, and the fourth groove 533d in the other end portion 533 is 20 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio of the thickness t divided by the thickness t' is defined as ratio 2. Ratio 2 under verification condition 11 is 0.1 (20 μm / 200 μm).

[0124] Regarding the residual nature of the safety valves 530 under verification condition 11, it was suggested that when all safety valves 530 were ruptured, the first groove 531a remained in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 remained in the lid 520 was that the ratio 2 was very small, at 0.1. When the second grooves 531b and the like, each having a thickness of 200 μm, were ruptured, the first groove 531a did not rupture, following the second grooves 531b and the like. This was because the rigidity of the first groove 531a in the safety valve 530 was sufficiently higher than the rigidity of the second grooves 531b and the like.

[0125] Regarding the standing ability of the safety valves 530 under verification condition 11, it was suggested that none of the safety valves 530 stood up when ruptured. The first groove 531a having a thickness of 200 μm does not rupture without following the second groove 531b, etc., when the second groove 531b, etc., having a thickness of 20 μm, is in a ruptured state, and is also very resistant to deformation. This is because the rigidity of the first groove 531a in the safety valve 530 is sufficiently higher than the rigidity of the second groove 531b, etc.

[0126] Under verification condition 12, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in one end portion 532, and the fourth groove 533d in the other end portion 533 is 40 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 12 is 0.2 (40 μm / 200 μm).

[0127] Regarding the residual nature of the safety valves 530 under verification condition 12, it was suggested that when all safety valves 530 were ruptured, the first groove 531a remained in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 remained in the lid 520 was that the ratio 2 was very small, at 0.2. When the second grooves 531b and the like, each having a thickness of 40 μm, were ruptured, the first groove 531a, which was 200 μm thick, did not rupture, following the second grooves 531b and the like. This was because the rigidity of the first groove 531a in the safety valve 530 was sufficiently higher than the rigidity of the second grooves 531b and the like.

[0128] Regarding the standing ability of the safety valve 530 under verification condition 12, it was suggested that a safety valve 530 that was about half erected slightly when ruptured. The term "about half erected safety valve 530" was determined by taking into consideration the ratio t / t' and the experimental results under verification conditions 14 and 16. The first groove 531a, which is 200 μm thick, does not rupture following the second groove 531b, etc., which is 40 μm thick, and is also difficult to deform. This is because the rigidity of the first groove 531a in the safety valve 530 is sufficiently higher than the rigidity of the second groove 531b, etc.

[0129] Under verification condition 13, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in the one end portion 532, and the fourth groove 533d in the other end portion 533 is 60 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 13 is 0.3 (60 μm / 200 μm).

[0130] Regarding the residual nature of the safety valves 530 under verification condition 13, it was suggested that when all safety valves 530 were ruptured, the first groove 531a remained in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 remained in the lid 520 was that the ratio 2 was small, at 0.3. When the second grooves 531b and the like, each having a thickness of 60 μm, were ruptured, the first groove 531a, which was 200 μm thick, did not rupture, following the second grooves 531b and the like. This was because the rigidity of the first groove 531a in the safety valve 530 was sufficiently higher than the rigidity of the second grooves 531b and the like.

[0131] Regarding the ability of the safety valve 530 to stand up under the verification condition 13, it was suggested that most of the safety valves 530 stand up when ruptured. When the second grooves 531b and the like having a thickness of 60 μm are ruptured, the first groove 531a having a thickness of 200 μm does not rupture without following the second grooves 531b and the like, but does deform.

[0132] Under verification condition 14, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in one end portion 532, and the fourth groove 533d in the other end portion 533 is 80 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 14 is 0.4 (80 μm / 200 μm).

[0133] Regarding the residual nature of the safety valves 530 under verification condition 14, it was suggested that when all safety valves 530 were ruptured, the first groove 531a remained in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 remained in the lid 520 was that the ratio 2 was small, at 0.4. When the second grooves 531b and the like, each having a thickness of 80 μm, were ruptured, the first groove 531a, which was 200 μm thick, did not rupture, following the second grooves 531b and the like. This was because the rigidity of the first groove 531a in the safety valve 530 was higher than the rigidity of the second grooves 531b and the like.

[0134] Regarding the standing ability of the safety valves 530 under the verification condition 14, it was suggested that all the safety valves 530 stood up sufficiently when ruptured. When the second grooves 531b and the like having a thickness of 80 μm are ruptured, the first grooves 531a having a thickness of 200 μm do not rupture without following the second grooves 531b and the like, but are sufficiently deformed.

[0135] FIG. 24 shows photographs of the experimental results under verification condition 14 in Table 2. The experiment was conducted a total of five times. The experiment was conducted by attaching a pressure vessel to the back surface 520b of the lid 520 and injecting water into the vessel to apply pressure to the safety valve 530. FIG. 25 shows a simulation image under condition 14 in Table 2. The simulation image shows the state immediately before the safety valve 530 bursts open.

[0136] Under verification condition 15, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in one end portion 532, and the fourth groove 533d in the other end portion 533 is 100 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 15 is 0.5 (100 μm / 200 μm).

[0137] Regarding the residual nature of the safety valves 530 under verification condition 15, it was suggested that when all safety valves 530 were ruptured, the first groove 531a remained in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 remained in the lid 520 was that the ratio 2 was small, at 0.5. When the second grooves 531b and the like, each having a thickness of 100 μm, were ruptured, the first groove 531a, which was 200 μm thick, did not rupture, following the second grooves 531b and the like. This was because the rigidity of the first groove 531a in the safety valve 530 was higher than the rigidity of the second grooves 531b and the like.

[0138] Regarding the standing ability of the safety valves 530 under the verification condition 15, it was suggested that all the safety valves 530 stood up sufficiently when ruptured. When the second grooves 531b and the like having a thickness of 100 μm are ruptured, the first grooves 531a having a thickness of 200 μm do not rupture without following the second grooves 531b and the like, but are sufficiently deformed.

[0139] Under verification condition 16, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in one end portion 532, and the fourth groove 533d in the other end portion 533 is 120 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 16 is 0.6 (120 μm / 200 μm).

[0140] Regarding the residual nature of the safety valve 530 under verification condition 16, it was suggested that in most cases of the safety valve 530, when it bursts, the first groove 531a remains in the recess 520f of the lid 520. The reason why the burst safety valve 530 remains in the lid 520 is that the ratio 2 is 0.6, which is a certain value exceeding half, 0.5. The first groove 531a, which is 200 μm thick, is unlikely to burst following the second groove 531b, etc., when the second groove 531b, etc., which is 120 μm thick, has burst. This is because the rigidity of the first groove 531a in the safety valve 530 is higher than the rigidity of the second groove 531b, etc.

[0141] Regarding the standing ability of the safety valves 530 under the verification condition 16, it was suggested that all the safety valves 530 stood up sufficiently when ruptured. When the second grooves 531b and the like having a thickness of 120 μm are ruptured, the first grooves 531a having a thickness of 200 μm do not rupture much without following the second grooves 531b and the like, but are sufficiently deformed.

[0142] FIG. 26 shows photographs of the experimental results under verification condition 16 in Table 2. The experiment was conducted a total of five times. The experiment was conducted by attaching a pressure vessel to the back surface 520b of the lid 520 and injecting water into the vessel to apply pressure to the safety valve 530. FIG. 27 shows a simulation image under condition 14 in Table 2. The simulation image shows the state immediately before the safety valve 530 bursts open.

[0143] Under verification condition 17, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in the one end portion 532, and the fourth groove 533d in the other end portion 533 is 140 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 17 is 0.7 (140 μm / 200 μm).

[0144] Regarding the residual nature of the safety valve 530 under verification condition 17, it was suggested that in approximately half of the safety valves 530, when they ruptured, the first groove 531a remained in the recess 520f of the lid 520. The reason why the ruptured safety valve 530 separates from the lid 520 is because the ratio 2 is high at 0.7. When the second grooves 531b and the like, each having a thickness of 140 μm, are ruptured, the first groove 531a, which is 200 μm thick, is likely to rupture following the second grooves 531b and the like. This is because the rigidity of the first groove 531a in the safety valve 530 is similar to the rigidity of the second grooves 531b and the like.

[0145] Regarding the standing ability of the safety valves 530 under the verification condition 17, it was suggested that all the safety valves 530 stood up sufficiently when ruptured. When the second grooves 531b and the like, each having a thickness of 140 μm, were ruptured, the first grooves 531a, each having a thickness of 200 μm, were ruptured about halfway along with the second grooves 531b, and were sufficiently deformed.

[0146] Under verification condition 18, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in the one end portion 532, and the fourth groove 533d in the other end portion 533 is 150 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 18 is 0.75 (150 μm / 200 μm).

[0147] Regarding the residual nature of the safety valves 530 under verification condition 18, it was suggested that when all safety valves 530 were ruptured, the first groove 531a did not remain in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 separated from the lid 520 was because the ratio 2 was high at 0.75. When the second grooves 531b and other grooves, each 150 μm thick, were ruptured, the first groove 531a, which was 200 μm thick, was likely to rupture following the second grooves 531b and other grooves. This was because the rigidity of the first groove 531a in the safety valve 530 was similar to the rigidity of the second grooves 531b and other grooves.

[0148] Regarding the standing ability of the safety valves 530 under the verification condition 18, it was suggested that all the safety valves 530 stood up sufficiently when ruptured. When the second grooves 531b and the like having a thickness of 150 μm were ruptured, the first grooves 531a having a thickness of 200 μm were ruptured and deformed sufficiently, following the second grooves 531b.

[0149] Under verification condition 19, as shown in Table 2, the thickness t of the second groove 531b in the central portion 531 of the safety valve 530, the third groove 532c in the one end portion 532, and the fourth groove 533d in the other end portion 533 is 175 μm. The thickness t' of the first groove 531a in the central portion 531 of the safety valve 530 is 200 μm. The ratio 2 under verification condition 19 is approximately 0.88 (175 μm / 200 μm).

[0150] Regarding the residual nature of the safety valves 530 under verification condition 19, it was suggested that when all safety valves 530 were ruptured, the first groove 531a did not remain in the recess 520f of the lid 520. The reason why the ruptured safety valves 530 separated from the lid 520 was because the ratio 2 was very high at 0.88. When the second grooves 531b and other grooves, each 175 μm thick, were ruptured, the first groove 531a, which was 200 μm thick, was very likely to rupture following the second grooves 531b and other grooves. This was because the rigidity of the first groove 531a in the safety valve 530 was very similar to the rigidity of the second grooves 531b and other grooves.

[0151] Regarding the standing ability of the safety valves 530 under the verification condition 19, it was suggested that all the safety valves 530 stood up sufficiently when ruptured. When the second grooves 531b and the like having a thickness of 175 μm were ruptured, the first grooves 531a having a thickness of 200 μm were ruptured and deformed sufficiently, following the second grooves 531b.

[0152] (Effects of the Safety Valve 530 and Battery 1 of the Embodiment) The effects of the safety valve 530 and battery 1 of the embodiment will be described with reference to Tables 1 and 2 and FIGS. 12 to 19. FIG.

[0153] (1) The safety valve 530 is formed with a linear first groove 531a, a linear second groove 531b, an arc-shaped third groove 532c, and an arc-shaped fourth groove 533d. The thickness of the first groove 531a is greater than the thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d. In other words, the first groove 531a is a thick-walled portion, and the second groove 531b, the third groove 532c, and the fourth groove 533d are thin-walled portions. With this configuration, rupture can be initiated from the second groove 531b, which is a linear thin-walled portion. The rupture of the safety valve 530 starts from the second groove 531b and progresses to the third groove 532c and the fourth groove 533d, and is likely to stop or be stopped at the end of the thick-walled portion of the first groove 531a.

[0154] Here, for example, if the center of the first groove 531a is thick-walled and both ends of the first groove 531a are thin-walled, there is a risk that the safety valve 530 may detach from the lid 520. Furthermore, for example, if at least a portion of the arc-shaped third groove 532c or fourth groove 533d is thick-walled, there is a risk that a sufficiently wide opening area may not be secured after rupture. In contrast, in the embodiment, the first groove 531a of the safety valve 530 is thick-walled throughout, and the third groove 532c and the fourth groove 533d do not have thick-walled portions. This makes it possible to obtain a safety valve 530 that can be sufficiently ruptured under a predetermined pressure while remaining in the exterior body, as well as a lid (exterior body) 520 and a battery 1 including the safety valve 530.

[0155] (2) The length d of the central portion 531 of the safety valve 530 along the longitudinal direction X (first direction) is 1 mm or more. The length d of the central portion 531 of the safety valve 530 is 0.5 to 3 times the diameter φ of the one end portion 532 and the other end portion 533. The thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 are 0.2 to 0.7 times the thickness of the first groove 531a.

[0156] (15) to (18) The battery 1 includes a charging / discharging unit 100, a lid 520 (exterior body) that houses the charging / discharging unit 100 and extends along the longitudinal direction X (first direction), and a safety valve 530 provided on the lid 520. The safety valve 530 may be provided on the container 510.

[0157] According to this configuration, the length d of the central portion 531 of the safety valve 530 along the longitudinal direction X (first direction) is set to 1 mm or more. That is, the length d of one end 531p and the other end 531q of the central portion 531 along the longitudinal direction X is set to 1 mm or more. By setting it in this manner, the safety valve 530 is provided with a rectangular portion in addition to the pair of semicircular portions. The safety valve 530 is ruptured starting from the rectangular portion.

[0158] Furthermore, with this configuration, the length d of the central portion 531 of the safety valve 530 is set to be 0.5 times or more and 3 times or less the diameter φ of the one end 532 and the other end 533. By setting the length d in this manner, as explained with reference to Table 1 and FIGS. 20 and 21 , the region in which the safety valve 530 begins to rupture can be kept within a certain range. When the safety valve 530 is subjected to a predetermined pressure, rupture begins from the region in the second groove 531b where the amount of displacement is greatest. The narrower the rupture initiation region of the safety valve 530, the more likely it is that the rupture initiation position will be stable and determined in the center of the second groove 531b. As a result, the safety valve 530 is more likely to rupture according to specifications.

[0159] Furthermore, with this configuration, the thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 are set to be 0.2 times or more and 0.7 times or less the thickness of the first groove 531a. By setting the thicknesses in this manner, as described with reference to Table 2 and Figures 22 to 25, the safety valve 530 can achieve both residuality and uprightness, which are in a trade-off relationship. The residuality of the safety valve 530 refers to whether or not the first groove 531a remains in the recess 520f of the lid 520 when the safety valve 530 ruptures. It is preferable to suppress or prevent interference between the safety valve 530 and surrounding components when the safety valve 530 ruptures. The uprightness of the safety valve 530 refers to whether or not the safety valve 530 bends sufficiently and uprights from the recess 520f of the lid 520 when the safety valve 530 ruptures. If the safety valve 530 bends sufficiently and stands upright when it is torn open, the pressure inside the battery 1 can be quickly reduced.

[0160] Therefore, the safety valve 530 of the battery 1 can be sufficiently ruptured by a predetermined pressure while remaining in the lid 520 .

[0161] (3) The second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 have the same thickness.

[0162] With this configuration, when a predetermined pressure is applied to the safety valve 530, the pressure can be applied evenly to the second groove 531b, the third groove 532c, and the fourth groove 533d, thereby allowing the safety valve 530 to be opened properly.

[0163] (4) The one end 532 and the other end 533 of the safety valve 530 are formed symmetrically with respect to the central portion 531 .

[0164] With this configuration, when a predetermined pressure is applied to the safety valve 530, the pressure can be applied evenly to the second groove 531b, the third groove 532c, and the fourth groove 533d, thereby allowing the safety valve 530 to be opened properly.

[0165] (5) The length d of the central portion 531 of the safety valve 530 is 0.5 times or more and less than 1 time the diameter φ of the one end 532 and the other end 533 .

[0166] According to this configuration, it is preferable to apply the safety valve 530 to a relatively high-capacity BEV-type battery 1. Compared to an HEV-type battery 1, a BEV-type battery 1 often has a length along the short side direction Y that is relatively shorter than the length along the long side direction X. That is, the aspect ratio of the safety valve 530 between the long side direction X and the short side direction Y is set to be relatively small in accordance with the shapes of the lid 520 and the container 510.

[0167] (6) The length d of the central portion 531 of the safety valve 530 is equal to or greater than 1 time and equal to or less than 3 times the diameter φ of the one end portion 532 and the other end portion 533 .

[0168] According to this configuration, it is preferable to apply the safety valve 530 to a relatively high-output (relatively low-capacity) HEV-type battery 1. Compared to a BEV-type battery 1, the length of an HEV-type battery 1 is often longer in the short direction Y than in the long direction X. That is, the aspect ratio of the safety valve 530 between the long direction X and the short direction Y is set relatively large in accordance with the shapes of the lid 520 and the container 510.

[0169] (7) The thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 are 0.3 times or more and 0.6 times or less the thickness of the first groove 531a.

[0170] With this configuration, the uprightness of the safety valve 530 shown in Table 2 can be further improved compared to when the thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 are set to be 0.2 times or more and less than 0.3 times the thickness of the first groove 531a. Also, the remaining durability of the safety valve 530 shown in Table 2 can be further improved compared to when the thicknesses of the second groove 531b, the third groove 532c, and the fourth groove 533d of the safety valve 530 are set to be more than 0.6 times and less than 0.7 times the thickness of the first groove 531a.

[0171] (9) The central portion 531 , one end portion 532 , and the other end portion 533 of the safety valve 530 are all curved convexly in a direction away from the charge / discharge body 100 .

[0172] With this configuration, when the safety valve 530 receives a predetermined pressure from the charging / discharging unit 100, the central portion 531, one end portion 532, and the other end portion 533 are likely to deform and rupture in a direction away from the charging / discharging unit 100, based on the convexly curved portion. The direction away from the charging / discharging unit 100 is the direction away from the battery 1.

[0173] (14) The central portion 531, one end portion 532, and the other end portion 533 of the safety valve 530 are integrally formed with the lid 520 (exterior body).

[0174] (19) The safety valve 530 is formed integrally with the lid 520 (exterior body).

[0175] According to this configuration, the safety valve 530 can be formed more easily than when the safety valve 530 and the lid 520 are formed separately.

[0176] In the safety valve 530, the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d are provided on the side farther from the charge / discharge body 100. The first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d are visible from the outside of the battery 1. The first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d are not visible from the charge / discharge body 100 side. Because the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d are formed in a thin groove shape, they may be visible as traces from the charge / discharge body 100 side.

[0177] With this configuration, when the safety valve 530 is formed by, for example, press-molding the lid 520, the material in the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d is likely to migrate away from the charging / discharging unit 100, i.e., to the outside of the battery 1. In other words, the safety valve 530 can suppress or prevent the material in the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d from migrating toward the side closer to the charging / discharging unit 100, i.e., to the inside of the battery 1. If the material in the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d migrates toward the side closer to the charging / discharging unit 100, the safety valve 530 may bulge convexly toward the charging / discharging unit 100.

[0178] (Safety Valve 810 of Modified Example 1 of the Embodiment) The safety valve 810 will be described with reference to FIG.

[0179] FIG. 28 is a perspective view showing a cross section of a safety valve 810 and a lid 520 according to the first modification of the embodiment.

[0180] (8) The central portion 811, one end portion 812, and the other end portion 813 of the safety valve 810 are at least partially convexly curved in a direction away from the charging / discharging body 100. In the first modified example of the embodiment, only a portion of the central portion 811 of the safety valve 810 is convexly curved in a direction away from the charging / discharging body 100. Only the entire central portion 811 may be configured to be convexly curved in a direction away from the charging / discharging body 100. The entire central portion 811, a portion of the one end portion 812, and a portion of the other end portion 813 may be configured to be convexly curved in a direction away from the charging / discharging body 100.

[0181] With this configuration, when the safety valve 530 receives a predetermined pressure from the side of the charging / discharging body 100, the central portion 531, one end portion 532, and the other end portion 533 deform and break in a direction away from the charging / discharging body 100, with the central portion 531 as the reference point.

[0182] (Safety Valve 820 of Modified Example 2 of the Embodiment) The safety valve 820 will be described with reference to FIG.

[0183] FIG. 29 is a perspective view showing a cross section of a safety valve 820 and a lid 520 according to the second modification of the embodiment.

[0184] (11) The central portion 821, one end portion 822, and the other end portion 823 of the safety valve 820 have an inner region that is annularly convexly curved and located farther from the charging / discharging body 100 than the outer region that is annularly convexly curved and located farther from the charging / discharging body 100. In the safety valve 820, the annular portion 820m that constitutes the convexly curved portion annularly surrounds the central portion 821, the one end portion 822, and the other end portion 823. In the safety valve 820, the annular portion 820m is located more inward than the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d. In the safety valve 820, the region 820s that is inward from the annular portion 820m is located higher in the height direction Z than the region 820t that is outward from the annular portion 820m. The central portion 821, one end portion 822, and the other end portion 823 of the safety valve 820 may include a portion where the region 820s is located farther from the charge / discharge body 100 than the region 820t.

[0185] With this configuration, when the safety valve 530 receives a predetermined pressure from the charging / discharging body 100 side, the central portion 531, one end portion 532 and the other end portion 533 deform and split in a direction away from the charging / discharging body 100, based on the region 820s inside the annular portion 820m.

[0186] (Safety Valve 830 of Modified Example 3 of the Embodiment) The safety valve 830 will be described with reference to FIG.

[0187] FIG. 30 is a perspective view showing a cross section of a safety valve 830 and a lid 520 according to the third modification of the embodiment.

[0188] (10) The central portion 831, one end portion 832, and the other end portion 833 of the safety valve 830 are annularly convexly curved in a direction away from the charging / discharging unit 100. In the safety valve 830, the annular portion 830m constituting the convexly curved portion annularly surrounds the areas of the central portion 831, one end portion 832, and the other end portion 833. In the safety valve 830, the annular portion 830m is located more inward than the first groove 531a, the second groove 531b, the third groove 532c, and the fourth groove 533d. It is sufficient that the central portion 831, the one end portion 832, and the other end portion 833 of the safety valve 830 include annularly convexly curved portions in a direction away from the charging / discharging unit 100.

[0189] With this configuration, when the safety valve 530 receives a predetermined pressure from the charging / discharging body 100 side, the central portion 531, one end portion 532 and the other end portion 533 deform and break apart in a direction away from the charging / discharging body 100, based on the annular portion 830m.

[0190] (Safety Valve 840 of Modified Example 4 of the Embodiment) The safety valve 840 will be described with reference to FIG.

[0191] FIG. 31 is a perspective view showing a cross section of a safety valve 840 and a lid 520 according to the fourth modification of the embodiment.

[0192] (12) In the safety valve 840, at least the first groove 531e is provided on the side farther from the charge / discharge body 100 and is formed in a trapezoidal shape that becomes relatively smaller toward the bottom. The first groove 531e is visible from the outside of the battery 1. The first groove 531e is not visible from the charge / discharge body 100 side. Because the first groove 531e is formed in a thin groove shape, it may be visible as a trace from the charge / discharge body 100 side. The first groove 531e only needs to include a portion formed in a trapezoidal shape with the top surface larger than the bottom surface. In other words, the first groove 531e does not need to be formed in a trapezoidal shape entirely. The second groove 531b, the third groove 532c, and the fourth groove 533d may also be provided on the side farther from the charge / discharge body 100 and may be formed in a trapezoidal shape that becomes relatively smaller toward the bottom surface.

[0193] With this configuration, when safety valve 840 is ruptured and the portion of first groove 531e of safety valve 840 is deformed toward the side farther from charging / discharging body 100, central portion 841 of safety valve 840 is less likely to interfere with the portion facing it across first groove 531e. In other words, central portion 841 of safety valve 840 can rise sufficiently, starting from first groove 531e.

[0194] (Safety Valve 850 of Modified Example 5 of the Embodiment) The safety valve 850 will be described with reference to FIG.

[0195] FIG. 32 is a perspective view showing a cross section of a safety valve 850 and a lid 520 according to the fifth modification of the embodiment.

[0196] (13) In the safety valve 850, at least the first groove 531f is provided on the side farther from the charging / discharging body 100 and is formed in a V-shape that narrows relatively toward the bottom. The first groove 531f is visible from the outside of the battery 1. The first groove 531f is not visible from the charging / discharging body 100 side. Because the first groove 531f is formed thinly in a groove shape, it may be visible as a trace from the charging / discharging body 100 side. The first groove 531f only needs to include a V-shaped portion whose top surface is larger than its bottom surface. In other words, the first groove 531f does not need to be formed in a V-shape entirely. The second groove 531b, the third groove 532c, and the fourth groove 533d may also be provided on the side farther from the charging / discharging body 100 and may be formed in a V-shape that narrows relatively toward the bottom surface.

[0197] With this configuration, when safety valve 850 is ruptured and the portion of first groove 531f of safety valve 850 is deformed toward the side farther from charging / discharging body 100, central portion 851 of safety valve 850 is less likely to interfere with the portion facing it via first groove 531f. In other words, central portion 851 of safety valve 850 can rise sufficiently, starting from first groove 531f.

[0198] (Safety Valve 860 of Modified Example 6 of the Embodiment) The safety valve 860 will be described with reference to FIG.

[0199] FIG. 33 is a perspective view showing a cross section of a safety valve 860 and a lid 520 according to the sixth modification of the embodiment.

[0200] In the safety valve 860, the first groove 531g, the second groove 531b, the third groove 532c, and the fourth groove 533d are provided on the side closer to the charging / discharging body 100. For example, in the central portion 861 of the safety valve 860, as shown in FIG. 33 , the first groove 531g is provided on the side closer to the charging / discharging body 100. The first groove 531g, the second groove 531b, the third groove 532c, and the fourth groove 533d are visible from the side of the charging / discharging body 100. The first groove 531g, the second groove 531b, the third groove 532c, and the fourth groove 533d are not visible from the outside of the battery 1. Because the first groove 531g, the second groove 531b, the third groove 532c, and the fourth groove 533d are formed in a thin groove shape, they may be visible as traces from the outside of the battery 1.

[0201] As described above, the safety valve 860 can be applied to a configuration in which the first groove 531g, the second groove 531b, the third groove 532c, and the fourth groove 533d are provided on the side closer to the charge / discharge body 100.

[0202] (Battery of Other Embodiments) The battery of the present invention is not limited to the configuration of the battery described in the embodiments, and can be configured appropriately based on the content described in the claims.

[0203] The embodiments are described in detail or simply to make the present invention easier to understand, and do not necessarily include all of the components described, or may include components not shown. Also, some of the components of the embodiments may be deleted, replaced with components of other embodiments, or combined with components of other embodiments.

[0204] The battery of the present invention is not limited to lithium-ion batteries. The battery of the present invention can be applied to, for example, nickel-metal hydride batteries and lead-acid batteries. The battery of the present invention is not limited to secondary batteries. The battery of the present invention can be applied to primary batteries. The charge / discharge body of the battery of the present invention is not limited to a wound type charge / discharge body in which a positive electrode, a separator, and a negative electrode, each formed in a long shape, are bundled and wound. The charge / discharge body of the battery of the present invention can also be a stacked type in which multiple rectangular positive electrodes, separators, and negative electrodes are alternately stacked on top of each other. The charge / discharge body of the battery of the present invention can also be a stacked type in which multiple relatively short positive electrodes and multiple negative electrodes are alternately arranged facing each other with the separator interposed between them, around a single long separator. In such a charge / discharge body, the separator is folded and stacked, so that the positive electrode and the negative electrode face each other with the separator interposed between them. The battery of the present invention is not limited to a configuration in which one charge / discharge body is provided. The battery of the present invention can be applied to a configuration in which two or more charge / discharge bodies are provided. The battery of the present invention is not limited to a configuration in which the charge / discharge body is sealed by a container and a lid. The battery of the present invention can be applied to a configuration in which the charge / discharge element is sealed with a laminate film.

[0205] REFERENCE SIGNS LIST 1 Battery, 100 Charge / discharge body, 110 Positive electrode, 111 Positive electrode current collecting layer, 112 Positive electrode active material layer, 120 Negative electrode, 121 Negative electrode current collecting layer, 122 Negative electrode active material layer, 130 Separator, 140 Electrolyte, 200 Current collector, 210 Positive electrode current collecting plate, 220 Negative electrode current collecting plate, 300 Current interrupter, 310 Diaphragm, 310a Main body, 310b First joint, 310c Second joint, 320 Conductive member, 330 Support, 340 Plug, 400 Electrode terminal, 410 Positive electrode terminal, 420 Negative electrode terminal, 421 First member, 422 Second member, 500 Housing 510 Container (exterior body), 520 lid (exterior body), 520a surface, 520b back surface, 520c positive electrode insertion hole, 520d negative electrode insertion hole, 520e liquid injection insertion hole, 520f recess, 520f1 first inner edge, 520f2 second inner edge, 520f3 third inner edge, 520f4 fourth inner edge, 530 safety valve, 531 central portion, 531a first groove, 531b second groove, 531e first groove, 531f first groove, 531g first groove, 531p one end, 531q other end, 532 one end, 532c third groove, 533 other end, 533d fourth groove, 540 sealing plug, 600 Insulator, 610 insulating cover, 620 positive electrode side insulating plate, 630 negative electrode side insulating plate, 700 sealing body, 710 positive electrode side first gasket, 720 positive electrode side second gasket, 730 negative electrode side first gasket, 740 negative electrode side second gasket, 810 safety valve, 811 central portion, 812 one end portion, 813 other end portion, 820 safety valve, 820m annular portion, 820s region, 820t region, 821 central portion, 822 one end portion, 823 other end portion, 830 safety valve, 830m annular portion, 831 central portion, 832 one end portion, 833 other end portion, 840 safety valve, 841 central portion, 850 safety valve 851 central portion, 860 safety valve, 861 central portion, X longitudinal direction (first direction), Y lateral direction (second direction),Z: Height direction.

Claims

1. A safety valve provided in a battery having: a charging / discharging unit; and an exterior body that houses the charging / discharging unit and extends along a first direction, wherein the exterior body includes a recess having: a first inner edge formed linearly along the first direction on one side of a second direction intersecting the first direction; a second inner edge formed linearly along the first direction on the other side of the second direction and facing the first inner edge along the second direction; a third inner edge connected to the first inner edge and the second inner edge and formed in an arc shape; and a fourth inner edge facing the third inner edge along the first direction and connected to the first inner edge and the second inner edge and formed in an arc shape; and a second end portion connected to the central portion in the recess and formed in a semicircular shape on the other end side of the central portion along the first direction, wherein the central portion, the one end portion and the other end portion are thinner than the exterior body, the central portion includes a first groove adjacent to the first inner edge and formed in a concave shape, and a second groove adjacent to the second inner edge and formed in a concave shape, the one end portion includes a third groove connected to the first groove and the second groove and formed in a concave shape adjacent to the third inner edge, the other end portion includes a fourth groove connected to the first groove and the second groove and formed in a concave shape adjacent to the fourth inner edge, the first groove and the second groove are formed in a straight line, the third groove and the fourth groove are formed in an arc shape, and a thickness of the first groove is thicker than a thickness of the second groove, the third groove and the fourth groove.

2. The safety valve according to claim 1, wherein the length of said central portion along said first direction is 0.5 to 3 times the diameter of said one end and said other end, and the thicknesses of said second groove, said third groove and said fourth groove are 0.2 to 0.7 times the thickness of said first groove.

3. The safety valve according to claim 1, wherein the second groove, the third groove and the fourth groove have the same thickness.

4. The safety valve according to claim 1, wherein the one end and the other end are formed symmetrically with respect to the central portion.

5. The safety valve according to claim 2, wherein the length of the central portion is 0.5 or more and less than 1 time the diameter of the one end and the other end.

6. The safety valve according to claim 2, wherein the length of the central portion is at least 1 time and at most 3 times the diameter of the one end and the other end.

7. The safety valve according to claim 2, wherein the thicknesses of the second groove, the third groove and the fourth groove are 0.3 times or more and 0.6 times or less the thickness of the first groove.

8. The safety valve according to claim 1, wherein the central portion, the one end portion and the other end portion are at least partially convexly curved in a direction away from the charge / discharge body.

9. The safety valve according to claim 1, wherein the central portion, the one end portion and the other end portion are all curved in a convex shape in a direction away from the charge / discharge body.

10. The safety valve according to claim 1, wherein the central portion, the one end portion and the other end portion include a portion that is annularly and convexly curved in a direction away from the charge / discharge body.

11. A safety valve as described in claim 10, wherein the central portion, the one end portion and the other end portion include a portion in which an annular, convexly curved inner region is located farther from the charge / discharge body than an annular, convexly curved outer region.

12. The safety valve according to claim 1, wherein at least the first groove is provided on a side farther from the charge / discharge body and includes a portion formed in a trapezoidal shape that becomes relatively smaller toward the bottom surface.

13. The safety valve according to claim 1, wherein at least the first groove is provided on a side farther from the charge / discharge body and includes a portion formed in a V-shape that becomes relatively smaller toward the bottom surface.

14. The safety valve according to claim 1, wherein the central portion, the one end portion and the other end portion are integrally formed with the exterior body.

15. An exterior body that houses a charge / discharge unit and extends along a first direction, the exterior body including a recess and a safety valve, the recess having: a first inner edge formed linearly along the first direction on one side of a second direction intersecting the first direction; a second inner edge formed linearly along the first direction on the other side of the second direction and facing the first inner edge along the second direction; a third inner edge connected to the first inner edge and the second inner edge and formed in an arc shape; and a fourth inner edge facing the third inner edge along the first direction and connected to the first inner edge and the second inner edge and formed in an arc shape, the safety valve having: a central portion formed in a rectangular shape in the recess of the exterior body; one end portion connected to the central portion in the recess and formed in a semicircular shape on one end side of the central portion along the first direction; and a second end portion connected to the central portion in the recess and formed in a semicircular shape on the other end side of the central portion along the first direction. an outer casing including: the central portion, the one end portion, and the other end portion are thinner than the outer casing; the central portion includes a first groove adjacent to the first inner edge and formed in a concave shape, and a second groove adjacent to the second inner edge and formed in a concave shape; the one end portion includes a third groove connected to the first groove and the second groove and formed in a concave shape adjacent to the third inner edge; and the other end portion includes a fourth groove connected to the first groove and the second groove and formed in a concave shape adjacent to the fourth inner edge; the first groove and the second groove are formed in a straight line; the third groove and the fourth groove are formed in an arc shape; and a thickness of the first groove is thicker than a thickness of the second groove, the third groove, and the fourth groove.

16. The exterior body described in claim 15, wherein the length of the central portion along the first direction is 0.5 to 3 times the diameter of the one end and the other end, and the thicknesses of the second groove, the third groove, and the fourth groove are 0.2 to 0.7 times the thickness of the first groove.

17. A device comprising: a charge / discharge unit; an exterior body that houses the charge / discharge unit and extends along a first direction; and a safety valve provided on the exterior body, wherein the exterior body includes a recess, wherein the recess has: a first inner edge formed linearly along the first direction on one side of a second direction intersecting the first direction; a second inner edge formed linearly along the first direction on the other side of the second direction and facing the first inner edge along the second direction; a third inner edge that is connected to the first inner edge and the second inner edge and formed in an arc shape; and a fourth inner edge that faces the third inner edge along the first direction and is connected to the first inner edge and the second inner edge and formed in an arc shape, wherein the safety valve has: a central portion formed in a rectangular shape in the recess of the exterior body; one end portion that is connected to the central portion in the recess and formed in a semicircular shape on one end side of the central portion along the first direction; a second end portion connected to the central portion at the recess and formed in a semicircular shape on the other end side of the central portion along the first direction, the central portion, the one end portion and the other end portion being thinner than the exterior body, the central portion including a first groove adjacent to the first inner edge and formed in a concave shape, and a second groove adjacent to the second inner edge and formed in a concave shape, the one end portion including a third groove connected to the first groove and the second groove and formed in a concave shape adjacent to the third inner edge, the other end portion including a fourth groove connected to the first groove and the second groove and formed in a concave shape adjacent to the fourth inner edge, the first groove and the second groove being formed in a straight line, the third groove and the fourth groove being formed in an arc shape, and a thickness of the first groove being thicker than a thickness of the second groove, the third groove and the fourth groove.

18. The battery described in claim 17, wherein the length of the central portion along the first direction is 0.5 to 3 times the diameter of the one end and the other end, and the thicknesses of the second groove, the third groove, and the fourth groove are 0.2 to 0.7 times the thickness of the first groove.

19. The battery according to claim 17, wherein the safety valve is formed integrally with the exterior body.

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