Battery and battery pack

Abstract

This battery comprises a charging / discharging body, an exterior body, an electrode terminal, and a sealing body. The electrode terminal includes a connection terminal (321) electrically connected to the charging / discharging body, and an external terminal (322) having an insertion hole (322a) into which the connection terminal (321) is inserted. The external terminal (322) includes a first member (322x) laser-bonded to the connection terminal (321), and a second member (322y) solid-phase bonded to the first member (322x). The connection terminal (321) includes a head part (321a) inserted into the insertion hole (322a) of the external terminal (322). The sealing body includes a seal part (flange part (632)) sandwiched between the head part (321a) of the connection terminal (321) and the exterior body (lid (420)). The diameter of an annular laser bonding part (323) where the inner edge of the insertion hole (322a) of the external terminal (322) and the outer edge of the head part (321a) of the connection terminal (321) are laser-bonded is greater than the maximum diameter of a portion of the seal part (flange part (632)) in contact with the head part (321a).

Description

Battery and Battery Pack

[0001] The present invention relates to a battery and a battery pack.

[0002] Conventionally, an electrode terminal formed by solid-phase bonding of two or more members has been known (see, for example, Patent Document 1).

[0003] Japanese Unexamined Patent Application Publication No. 2016-207510

[0004] When a second member is solid-phase bonded to a first member and another member is further laser-bonded to the second member to form an electrode terminal, there is a demand for a battery and a battery pack capable of suppressing damage to the laser-bonded portion.

[0005] The battery includes a charge / discharge body, an exterior body that houses the charge / discharge body, an electrode terminal that penetrates the exterior body and is electrically connected to the charge / discharge body, and a sealing body that seals while insulating between the exterior body and the electrode terminal. The electrode terminal includes a first metal, a connection terminal electrically connected to the charge / discharge body, and an external terminal having an insertion hole into which the connection terminal is inserted and that contacts the outer edge of the connection terminal. The external terminal includes the first metal, a first member laser-bonded to the connection terminal, a second metal having a material different from the first metal, and a second member laminated on and solid-phase bonded to the first member. The connection terminal includes a head inserted into the insertion hole of the external terminal and an insertion portion that protrudes from the head toward the charge / discharge body and penetrates a through-hole of the exterior body. The sealing body includes a seal portion sandwiched between the head of the connection terminal and the exterior body. A laser-bonded portion where the inner edge of the insertion hole of the external terminal and the outer edge of the head of the connection terminal are laser-bonded is formed in an annular shape along the inner edge of the insertion hole. The diameter of the annular laser-bonded portion is larger than the maximum diameter of the portion that contacts the head in the seal portion.

[0006] The battery pack has the battery and a bus bar joined to the electrode terminal.

[0007] According to the present invention, a battery and a battery pack capable of suppressing damage to the laser-bonded portion can be obtained.

[0008] A perspective view showing the battery pack 1 of the first embodiment. A perspective view of the battery pack 1 of Figure 1, with the gas duct 61 removed. A top view of the battery pack 1 of Figure 1, with the busbar holder 34 removed. A perspective view showing a plurality of batteries 10 and a holding unit 20, with some of the components of the holding unit 20 disassembled in the width direction Y and the stacking direction X. A perspective view from Figure 4, with the first side plate 26P, the second side plate 26Q and the fastening bolt 27 removed, and the components of the battery 10 and the holding unit 20 disassembled in the stacking direction X. A perspective view showing the busbar unit 30, the voltage detection unit 40 and the temperature measurement unit 50. A perspective view showing the battery 10 of the first embodiment. A perspective view showing a cross-sectional view of the components around the negative terminal 320 of the battery 10. A side view showing the components of Figure 8. A perspective view showing a cross-sectional view of the components around the positive terminal 310 of the battery 10. A side view showing the components of Figure 10. A perspective view showing a partially disassembled battery 10. A perspective view showing the charge / discharge body 100 of battery 10. A side view showing a cross-section of a part of the charge / discharge body 100 of Figure 13. A side view showing a cross-section of a part of the charge / discharge body 700 of a modified example. A perspective view showing a disassembled view of the components around the negative electrode terminal 320 of battery 10. A perspective view showing a disassembled view of the components around the opening valve 430 and sealing plug 440 of battery 10. A perspective view showing a disassembled view of the components around the positive electrode terminal 310 of battery 10. A side view showing a cross-section of the negative electrode terminal 320 and its surrounding components of the first embodiment. A side view showing an enlarged view of region F20 of Figure 19. A side view showing an enlarged view of region F21 of Figure 20. A side view showing an enlarged cross-section of the negative electrode terminal 1120 and its surrounding components of modified example 1 of the first embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1220 and its surrounding components of modified example 2 of the first embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1320 and its surrounding components in the second embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1420 and its surrounding components in the third embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1520 and its surrounding components in the fourth embodiment.

[0009] Embodiments for carrying out the present invention will be described with reference to the drawings. In order to facilitate understanding of each embodiment, the size and proportions of the components may be exaggerated in each drawing. In each drawing, the same reference numerals are assigned to the same components. In each drawing, the stacking direction X, width direction Y, and height direction Z of the battery pack 1 are indicated by arrows. However, in each drawing, the stacking direction X, width direction Y, and height direction Z of the battery pack 1 indicate the relative positional relationship within the same drawing. That is, if the battery pack 1 is rotated 180 degrees and the top and bottom surfaces are reversed, or if the battery pack 1 is rotated 90 degrees and the top surface is positioned as the side surface, the stacking direction X, width direction Y, and height direction Z of the battery pack 1 will change. In each drawing, the threads on the outer surface of the fastening bolts and the grooves on the inner surface of the insert nuts are omitted from the illustration. In each drawing, the longitudinal direction A, the short direction B, and the height direction Z of the battery 10 are indicated by arrows. In each drawing, the longitudinal direction A, the short direction B, and the height direction Z of the battery 10 indicate the relative positional relationship within the same drawing. That is, if the battery 10 is rotated 180 degrees and its top and bottom surfaces are reversed, or if the battery 10 is rotated 90 degrees and its top surface becomes the side surface, the longitudinal direction A, the short direction B, and the height direction Z of the battery 10 will change.

[0010] (Configuration of the battery pack 1 in the first embodiment) The configuration of the battery pack 1 in the first embodiment will be described with reference to Figures 1 to 22.

[0011] Figure 1 is a perspective view showing a battery pack 1 of the first embodiment. Figure 2 is a perspective view of the battery pack 1 of Figure 1, with the gas duct 61 removed. Figure 3 is a top view of the battery pack 1 of Figure 1, with the busbar holder 34 removed. Figure 4 is a perspective view showing a plurality of batteries 10 and a holding unit 20, with some of the components of the holding unit 20 disassembled in the width direction Y and the stacking direction X. Figure 5 is a perspective view showing the first side plate 26P, the second side plate 26Q and the fastening bolts 27 removed from Figure 4, and with the components of the batteries 10 and the holding unit 20 disassembled in the stacking direction X. Figure 6 is a perspective view showing a busbar unit 30, a voltage detection unit 40 and a temperature measurement unit 50.

[0012] Figure 7 is a perspective view showing a battery 10 of the first embodiment. Figure 8 is a perspective view showing a cross-sectional view of the components around the negative electrode terminal 320 of the battery 10. Figure 9 is a side view showing the components of Figure 8. Figure 10 is a perspective view showing a cross-sectional view of the components around the positive electrode terminal 310 of the battery 10. Figure 11 is a side view showing the components of Figure 10. Figure 12 is a perspective view showing the battery 10 partially disassembled. Figure 13 is a perspective view showing the charge / discharge body 100 of the battery 10. Figure 14 is a side view showing a cross-sectional view of a part of the charge / discharge body 100 of Figure 13. Figure 15 is a side view showing a cross-sectional view of a part of a modified charge / discharge body 100. Figure 16 is a perspective view showing a disassembled view of the components around the negative electrode terminal 320 of the battery 10. Figure 17 is a perspective view showing a disassembled view of the components around the opening valve 430 and sealing plug 440 of the battery 10. Figure 18 is a perspective view showing the components around the positive terminal 310 of the battery 10 in an exploded view.

[0013] (Configuration of battery pack 1) Battery pack 1 is configured, for example, as a power source to operate a motor for driving a vehicle. Battery pack 1 may also be configured, for example, as a power source to operate electrical equipment mounted on the vehicle.

[0014] As shown in Figure 1, the battery pack 1 includes a plurality of batteries 10, a holding unit 20 for holding the plurality of batteries 10, and a busbar unit 30 for electrically connecting the plurality of batteries 10. The battery pack 1 also includes a voltage detection unit 40 for detecting the voltage of the batteries 10, a temperature measuring unit 50 for measuring the temperature of the batteries 10, and a gas exhaust unit 60 for exhausting gases emitted from the batteries 10. The components included in the battery pack 1 will be described below.

[0015] (Configuration of Battery 10 in Battery Pack 1) The configuration of Battery 10 will be explained with reference to Figures 1 to 5 and Figures 7 to 18.

[0016] (Configuration of Battery 10) The batteries 10 shown in Figures 1 to 5 are stacked along the stacking direction X via a holding unit 20. As shown in Figure 3, for example, 20 batteries 10 are stacked. The batteries 10 are composed of, for example, lithium-ion secondary batteries.

[0017] As shown in Figure 5, the battery 10 is formed in a rectangular shape. A positive electrode terminal 310 and a negative electrode terminal 320 are provided on the upper surface 10a of the battery 10 along the stacking direction X. In Figure 5, the upper surface 10a corresponds to the top surface of the battery 10. The upper surface 10a is formed in a rectangular shape. The length of the upper surface 10a along the width direction Y of the battery 10 is longer than the length of the upper surface 10 along the stacking direction X of the battery 10. The upper surface 10a faces the busbar unit 30 shown in Figure 1. The two side surfaces 10b of the battery 10 along the stacking direction X face the upper surface 10a perpendicularly. The side surfaces 10b are formed in a rectangular shape. The length of the side surfaces 10b along the height direction Z of the battery 10 is longer than the length of the side surfaces 10b along the stacking direction X of the battery 10. The two main surfaces 10c of the battery 10 facing the stacking direction X are in contact with the cell spacers 22 of the holding unit 20, etc.

[0018] The battery 10 includes a charge / discharge unit 100 for charging and discharging electricity, a current collector 200 connected to the charge / discharge unit 100, electrode terminals 300 connected to the current collector 200, an outer casing 400 in which the components of the battery 10 are housed or attached, an insulator 500 that insulates the components of the battery 10 from the outer casing 400, and a sealant 600 that seals the components of the battery 10 from the outer casing 400.

[0019] (Configuration of the charge / discharge unit 100 of the battery 10) The charge / discharge unit 100 charges and discharges electricity. The charge / discharge unit 100 shown in Figures 8 to 14 includes a positive electrode 110, a negative electrode 120, a separator 130, and an electrolyte 140. The charge / discharge unit 100 is constructed by winding components, in which the positive electrode 110, separator 130, negative electrode 120, and separator 130 are stacked in that order, into a rectangular shape. The charge / discharge unit 100 may be constructed by winding or by stacking.

[0020] The positive electrode 110 includes a long positive electrode current collector layer 111 and a positive electrode active material layer 112 bonded to both sides of the positive electrode current collector layer 111. The positive electrode current collector layer 111 includes a current collector portion 111a and a positive electrode tab 111b. The positive electrode active material layer 112 is bonded to the current collector portion 111a. As shown in Figure 14, the positive electrode active material layer 112 faces, for example, the entire area along the short direction of the current collector portion 111a. The positive electrode tab 111b protrudes from the side edge 111c along the longitudinal direction of the current collector portion 111a in the short direction of the current collector portion 111a. The positive electrode tab 111b is formed integrally with the current collector portion 111a. Multiple positive electrode tabs 111b are formed on one current collector portion 111a. The positive electrode 110 may be configured such that a positive electrode active material layer 112 is bonded to only one side of the positive electrode current collector layer 111. The positive electrode current collector 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 composed of a lithium-containing composite oxide, a binder, and a conductive additive. Examples of lithium-containing composite oxides include metallic elements such as nickel (Ni), cobalt (Co), and manganese (Mn), and lithium (Li).

[0021] The negative electrode 120 includes a long negative electrode current collector layer 121 and a negative electrode active material layer 122 bonded to both sides of the negative electrode current collector layer 121. The negative electrode current collector layer 121 includes a current collector portion 121a and a negative electrode tab 121b. As shown in Figure 14, the current collector portion 121a of the negative electrode 120 is wider in the short direction compared to the current collector portion 111a of the positive electrode 110. The ends of the current collector portion 111a of the positive electrode 110 are located within the range of the current collector portion 121a of the negative electrode 120 in the short direction, via a separator 130. The negative electrode active material layer 122 is bonded to the current collector portion 121a. The negative electrode active material layer 122 faces, for example, the entire area of ​​the current collector portion 121a in the short direction. The negative electrode tab 121b protrudes from the side edge 121c along the longitudinal direction of the current collector 121a in the short direction of the current collector 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 collector 121a. Multiple negative electrode tabs 121b are formed on one current collector 121a. The negative electrode 120 may be configured by joining the negative electrode active material layer 122 to only one side of the negative electrode current collector layer 121. The negative electrode current collector 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 composed of carbon-based materials, a binder, and a conductive additive. For example, graphite is used as the carbon-based material.

[0022] The separator 130 insulates the positive electrode 110 and the negative electrode 120 while allowing lithium ions to pass through. The separator 130 is formed in a long, rectangular shape. As shown in Figure 14, the separator 130 has a longer width in the shorter direction compared to the current collector portion 111a of the positive electrode 110 and the current collector portion 121a of the negative electrode 120. Both ends of the current collector portion 111a of the positive electrode 110 and both ends of the current collector portion 121a of the negative electrode 120 are located within the range of the separator 130 in the shorter direction. The separator 130 is made of a porous material. Polyethylene (PE) or polypropylene (PP) are used for the separator 130. An insulating material may be used instead of the separator 130. The insulating member may be provided on the side of the positive electrode 110 facing the negative electrode 120. The insulating member may also be provided on the side of the negative electrode 120 facing the positive electrode 110. The insulating member may be made of a heat-resistant material. In such a configuration, the separator 130 is not essential.

[0023] The electrolyte 140 facilitates the flow of lithium ions between the positive electrode 110 and the negative electrode 120. The electrolyte 140 is also called an electrolyte solution. The electrolyte 140 contains a solvent and a solute. The electrolyte 140 may also contain additives. The solvent may include, for example, an organic solvent. For example, a carbonate ester such as ethylene carbonate is used as the organic solvent. The solute may include, for example, a lithium salt. For example, lithium hexafluoride phosphate (LiPF) is used as the lithium salt. ６ ) is used.

[0024] A modified example of the charge / discharge body 100, the charge / discharge body 700, will be described with reference to Figure 15. The configuration of the positive electrode 710 of the charge / discharge body 700 differs from the configuration of the positive electrode 110 of the charge / discharge body 100. In the configuration of the charge / discharge body 700, the same reference numerals are used for components that are the same as those in the charge / discharge body 100, and their explanation is omitted. The positive electrode active material layer 711 of the charge / discharge body 700 faces the portion of the current collector 111a excluding both ends along the short direction. The heat-resistant insulating layer 712 of the charge / discharge body 700 is joined to both ends along the short direction of the current collector 111a and to the base end portion of the positive electrode tab 111b.

[0025] (Configuration of the current collector 200 of the battery 10) The current collector 200 is connected to the charge / discharge unit 100. The current collector 200 is also called a current collector plate. The current collector 200 shown in Figures 8 to 11, 16 and 18 includes a positive electrode current collector plate 210 and a negative electrode current collector plate 220.

[0026] The positive electrode current collector plate 210 provides electrical contact between the positive electrode tab 111b of the charge / discharge body 100 and the positive electrode terminal 310. The positive electrode current collector plate 210 includes a rectangular plate-shaped base portion 210a and an insertion hole 210b that penetrates the base portion 210a. The insertion portion 310b of the positive electrode terminal 310 is inserted into the insertion hole 210b of the positive electrode current collector plate 210. The positive electrode current collector plate 210 is formed of, for example, aluminum or an aluminum alloy.

[0027] The negative electrode current collector plate 220 provides electrical contact between the negative electrode tab 121b of the charge / discharge body 100 and the negative electrode terminal 320. The negative electrode current collector plate 220 includes a rectangular plate-shaped base portion 220a and an insertion hole 220b that penetrates the base portion 220a. The insertion portion 320b of the negative electrode terminal 320 is inserted into the insertion hole 220b of the negative electrode current collector plate 220. The negative electrode current collector plate 220 is formed of, for example, copper or a copper alloy.

[0028] (Configuration of the electrode terminals 300 of the battery 10) The electrode terminals 300 are connected to the current collector 200. The electrode terminals 300 shown in Figures 7 to 12, 16, and 18 include a positive electrode terminal 310 and a negative electrode terminal 320.

[0029] The positive electrode terminal 310 is connected to the positive electrode current collector plate 210, for example, as shown in Figure 11. As shown in Figures 10, 11, and 18, the positive electrode terminal 310 includes a rectangular plate-shaped base portion 310a, a cylindrical insertion portion 310b protruding downward from the base portion 310a in Figure 10, and a cylindrical joint portion 310c protruding downward from the outer circumference of the insertion portion 310b in Figure 10. The base portion 310a is in contact with the base portion 620a of the positive electrode side second gasket 620. The insertion portion 310b is inserted into the insertion hole 620b of the positive electrode side second gasket 620, the positive electrode side insertion hole 420a of the cover 420, the insertion hole 520b of the positive electrode side insulating plate 520, and the insertion hole 210b of the positive electrode current collector plate 210. As shown in Figures 11 and 18, the joint portion 310c protrudes downward from the insertion hole 210b of the positive electrode current collector plate 210 and is expanded radially outward to join with the positive electrode current collector plate 210. In other words, the joint portion 310c is crimped to the positive electrode current collector plate 210. Furthermore, the joint portion 310c is welded to the positive electrode current collector plate 210. The positive electrode terminal 310 is formed of, for example, aluminum or an aluminum alloy.

[0030] (Configuration of the negative electrode terminal 320 (electrode terminal)) The configuration of the negative electrode terminal 320 will be described with reference to Figures 8, 9, 16, 19, and 20. Figure 19 is a cross-sectional side view of the negative electrode terminal 320 of the first embodiment and its surrounding components. Figure 20 is an enlarged view of region F20 in Figure 19. The negative electrode terminal 320 corresponds to the electrode terminal.

[0031] The negative electrode terminal 320 is connected to the negative electrode current collector plate 220, for example, as shown in Figure 9. The negative electrode terminal 320 includes a rectangular plate-shaped base portion 320a, a cylindrical insertion portion 320b protruding downward from the base portion 320a in Figure 9, and a cylindrical joint portion 320c protruding downward from the outer circumference of the insertion portion 320b in Figure 9. The base portion 320a is in contact with the base portion 640a of the negative electrode side second gasket 640. The insertion portion 320b is inserted into the insertion hole 640b of the negative electrode side second gasket 640, the negative electrode side insertion hole 420b of the cover 420, the insertion hole 530b of the negative electrode side insulating plate 530, and the insertion hole 220b of the negative electrode current collector plate 220. As shown in Figures 9 and 16, the joint portion 320c protrudes downward from the insertion hole 220b of the negative electrode current collector plate 220 and is expanded radially outward to join with the negative electrode current collector plate 220. In other words, the joint portion 320c is crimped to the negative electrode current collector plate 220. Furthermore, the joint portion 320c is welded to the negative electrode current collector plate 220.

[0032] The negative terminal 320 includes a connection terminal 321 and an external terminal 322. The details of the configuration of the negative terminal 320 will be described below, mainly with reference to Figure 20. The lower part of Figure 20 shows an enlarged view of region F20 in Figure 19. The upper part of Figure 20 shows a partially enlarged view including the laser joint 323 of the connection terminal 321 and the external terminal 322. The external terminal 322 includes a first member 322x and a second member 322y. The first member 322x of the connection terminal 321 and the external terminal 322 is formed of, for example, copper or a copper alloy. The second member 322y of the external terminal 322 is formed of, for example, aluminum or an aluminum alloy.

[0033] At the external terminal 322, the first member 322x and the second member 322y are joined by solid-state bonding. Solid-state bonding includes pressure welding, diffusion bonding, friction welding, and ultrasonic bonding. In this embodiment, as an example, solid-state bonding by pressure welding is applied. Pressure welding includes hot pressure welding and room temperature (cold) pressure welding. In hot pressure welding, the first member 322x and the second member 322y are heated and joined by pressing them against each other with relatively high pressure. In room temperature pressure welding, the first member 322x and the second member 322y are joined by pressing them against each other with relatively high pressure.

[0034] The joining surface 322z between the first member 322x and the second member 322y has a surface perpendicular to the height direction Z of the battery 10 and a surface parallel to the height direction Z of the battery 10.

[0035] As shown in Figures 8, 9, and 16, the external terminal 322 is formed in the shape of a rectangular flat plate. The external terminal 322 in this embodiment is formed from a so-called inlay-type clad material. The clad material used as the external terminal 322 is formed by solid-state bonding of the first member 322x and the second member 322y, with the first member 322x being embedded in a recess formed in the second member 322y, which is a rectangular flat plate made of an aluminum-based material. In this embodiment, an example in which the external terminal 322 is formed from an inlay-type clad material is described, but the external terminal 322 may also be formed from an edgelay-type clad material. In this case, the copper-based material is embedded in a recess formed in the corner of the rectangular flat plate made of an aluminum-based material and solid-state bonded.

[0036] As shown in Figure 20, the external terminal 322 has an insertion hole 322a that penetrates through the battery 10 in the height direction Z. The connection terminal 321 is inserted into the insertion hole 322a. The external terminal 322 consists of a first member 322x and a second member 322y stacked in the height direction Z, at least around the insertion hole 322a. Around the insertion hole 322a, the second member 322y is located further away from the charge / discharge body 100 than the first member 322x.

[0037] The insertion hole 322a includes a circular large-diameter hole 322a1 and a circular small-diameter hole 322a2 with a smaller inner diameter than the large-diameter hole 322a1. The large-diameter hole 322a1 is located on the busbar 32 side (upper side in Figure 20). The small-diameter hole 322a2 is located on the lid 420 side (lower side in Figure 20). The large-diameter hole 322a1 and the small-diameter hole 322a2 are arranged concentrically. A stepped surface 322a3, which is a surface perpendicular to the height direction Z, is formed between the large-diameter hole 322a1 and the small-diameter hole 322a2.

[0038] The end face of the external terminal 322 on the busbar 32 side has a terminal surface 322b that contacts the busbar 32 (see Figure 19). The end face of the external terminal 322 on the busbar 32 side corresponds to the end face of the second member 322y of the external terminal 322 on the busbar 32 side. The end face of the external terminal 322 on the busbar 32 side is the end face of the external terminal 322 in the height direction Z (upper end face and lower end face in Figure 20) that is opposite to the side on which the charge / discharge body 100 is located.

[0039] The connection terminal 321 includes a head portion 321a that forms part of the base portion 320a. The connection terminal 321 also includes the insertion portion 320b and the joining portion 320c described above. The insertion portion 320b protrudes from the head portion 321a toward the charge / discharge body 100 and passes through the negative electrode side insertion hole (through hole) 420b of the cover 420.

[0040] As shown in Figures 8 and 16, the head portion 321a is formed in a generally disc shape. As shown in Figure 20, the head portion 321a is inserted into the insertion hole 322a of the external terminal 322. The end face of the head portion 321a on the busbar 32 side, i.e., the end face 321a1 of the connection terminal 321 on the busbar 32 side, is located on the lid 420 side (lower side in Figure 20) than the terminal face 322b of the external terminal 322. The end face 321a1 of the connection terminal 321 on the busbar 32 side is the end face of the connection terminal 321 on the opposite side from the side where the charge / discharge body 100 is located, out of the end faces in the height direction Z of the connection terminal 321 (upper and lower end faces in Figure 20).

[0041] The head portion 321a includes a large-diameter portion 321a2 inserted into the large-diameter hole 322a1 and a small-diameter portion 321a3 inserted into the small-diameter hole 322a2. The large-diameter portion 321a2 and the small-diameter portion 321a3 are arranged concentrically. The outer diameter of the small-diameter portion 321a3 is smaller than the outer diameter of the large-diameter portion 321a2. A stepped surface 321a4, which is a surface orthogonal to the height direction Z, is formed between the large-diameter portion 321a2 and the small-diameter portion 321a3.

[0042] Fitting concave portions 322a4 and fitting convex portions 321a5, which are fitting portions that fit with and contact each other, are provided on the inner peripheral surface of the insertion hole 322a of the external terminal 322 and the outer peripheral surface of the head portion 321a of the connection terminal 321, respectively.

[0043] The large-diameter portion 321a2 of the head portion 321a of the connection terminal 321 includes a fitting convex portion 321a5 that protrudes outward in the radial direction of the connection terminal 321. In other words, the outer peripheral portion of the large-diameter portion 321a2 is formed as the fitting convex portion 321a5. The large-diameter hole 322a1 of the insertion hole 322a of the external terminal 322 includes a fitting concave portion 322a4 that depresses outward in the radial direction of the insertion hole 322a. In other words, the outer peripheral portion of the large-diameter hole 322a1 is formed as the fitting concave portion 322a4.

[0044] The fitting concave portion 322a4 of the external terminal 322 is a concave portion that depresses facing the outer peripheral surface of the head portion 321a of the connection terminal 321. The fitting convex portion 321a5 of the connection terminal 321 is a convex portion that protrudes toward the external terminal 322. The fitting convex portion 321a5 and the fitting concave portion 322a4 are in contact with each other at least in the stacking direction (height direction Z) of the first member 322x and the second member 322y. That is, the stepped surface 322a3 of the fitting concave portion 322a4 and the stepped surface 321a4 of the fitting convex portion 321a5 are in contact with each other.

[0045] Thereby, the positions of the external terminal 322 and the connection terminal 321 in the height direction Z are defined. Therefore, the fitting convex portion 321a5 and the fitting concave portion 322a4 can be used for positioning the external terminal 322 and the connection terminal 321 in the height direction Z.

[0046] The negative electrode terminal 320 is formed before being attached to the lid 420 together with other members. By forming an insertion hole 322a in an inlay type or edge ray type rectangular flat plate-shaped clad material, an external terminal 322 is formed. The fitting recess 322a4 is provided in the second member 322y of the external terminal 322. Therefore, both the insertion hole 322a and the fitting recess 322a4 can be formed by hole machining such as cold forging or press working, so the manufacturability is good. Note that the external terminal 322 may be formed by solid-phase bonding the first member 322x and the second member 322y in which the insertion hole 322a is formed in advance.

[0047] The connection terminal 321 is inserted into the insertion hole 322a of the external terminal 322 from above in FIG. 20. By the stepped surface 321a4 of the fitting convex portion 321a5 contacting the stepped surface 322a3 of the fitting recess 322a4, the positioning of the external terminal 322 and the connection terminal 321 is performed. By the positioning, the lower surface of the outer peripheral portion of the head 321a of the connection terminal 321 and the lower surface of the external terminal 322 are flush. The inner joint portion 321a6 of the connection terminal 321 and the outer joint portion 322a5 of the external terminal 322 are abutted. The inner joint portion 321a6 corresponds to the lower end portion of the outer peripheral portion of the head 321a of the connection terminal 321. The outer joint portion 322a5 corresponds to the opening edge portion on the lower end side of the insertion hole 322a of the external terminal 322.

[0048] A laser is irradiated from below in FIG. 20 toward the boundary surface between the inner joint portion 321a6 and the outer joint portion 322a5, and the external terminal 322 and the connection terminal 321 are laser-bonded. Note that in the laser bonding process, the arrangement relationship between the connection terminal 321 and the external terminal 322 is upside down from that in FIG. 20. Thereby, the laser bonding portion 323 is formed in a portion including the contact interface between the small-diameter hole 322a2 of the external terminal 322 and the small-diameter portion 321a3 of the connection terminal 321. That is, the laser bonding portion 323 is formed in an annular shape along the inner edge of the insertion hole 322a. The outer joint portion 322a5 and the inner joint portion 321a6 are integrated by laser bonding. Thereby, the external terminal 322 and the connection terminal 321 are integrated, and the negative electrode terminal 320 is formed. Thereafter, the negative electrode terminal 320 is attached to the lid 420 together with other members.

[0049] The end face 321a1 of the connection terminal 321 is located closer to the charge / discharge body 100 than the opening end face of the insertion hole 322a on the busbar 32 side. Therefore, a downwardly recessed circular recess 320d is formed on the upper surface of the negative electrode terminal 320. The bottom surface of the recess 320d is formed by the end face 321a1 of the connection terminal 321, and the side surface of the recess is formed by the inner circumferential surface of the insertion hole 322a of the external terminal 322. The end face 321a1 of the connection terminal 321 is located closer to the charge / discharge body 100 than the terminal surface 322b of the external terminal 322. Therefore, when welding the busbar 32 to the negative electrode terminal 320, interference between the connection terminal 321 and the busbar 32 is prevented. This allows the busbar 32 and the external terminal 322 to be overlapped and welded with the busbar 32 in contact with the terminal surface 322b of the external terminal 322.

[0050] Of the joining surfaces 322z between the first member 322x and the second member 322y, the surface perpendicular to the height direction Z is located to the side of the small-diameter portion 321a3 of the connecting terminal 321. Of the external terminals 322, the member that is laser-bonded to the connecting terminal 321 is the first member 322x, which contains the same type of metal as the connecting terminal 321. The outer edge of the small-diameter portion 321a3 of the head 321a of the connecting terminal 321 is in contact with the inner edge of the small-diameter hole 322a2 of the external terminal 322.

[0051] The inner edge of the insertion hole 322a of the external terminal 322 and the outer edge of the head 321a of the connecting terminal 321 are laser-bonded, thereby forming an annular laser-bonded portion 323 along the inner edge of the insertion hole 322a. The dimension (depth) of the laser-bonded portion 323 in the height direction Z is shorter than the thickness of the first member 322x.

[0052] A disc-shaped pressing projection 321d is formed on the lower surface of the head portion 321a, projecting downward in Figure 20. The outer diameter of the pressing projection 321d is larger than the outer diameter of the insertion portion 320b and smaller than the outer diameter of the small diameter portion 321a3. The pressing projection 321d presses the negative electrode side first gasket 630 downward in Figure 20.

[0053] The negative electrode terminal 320 is crimped to the negative electrode current collector plate 220 with the negative electrode side first gasket 630 elastically deformed. The connection terminal 321 is electrically connected to the charge / discharge element 100 of the battery 10 via the negative electrode current collector plate 220.

[0054] (Configuration of the battery 10's casing 400) The casing 400 houses or mounts the components of the battery 10. The casing 400 shown in Figures 7 to 12 and Figures 16 to 18 includes a container 410, a lid 420, a detachable valve 430, and a sealing plug 440.

[0055] The container 410 houses the charge / discharge unit 100, etc. The container 410 is made of a rectangular metal can. The container 410 includes an opening 410a that opens along the longitudinal direction and a housing portion 410b that is connected to the opening 410a. The container 410 is made of, for example, aluminum or an aluminum alloy.

[0056] The lid 420 seals the opening 410a of the container 410. The container 410 is formed from a long, plate-shaped metal sheet. The lid 420 has a positive electrode side insertion hole 420a, which is a circular through-hole, at one end in the longitudinal direction A. The insertion portion 310b of the positive electrode terminal 310 and the positive electrode side first gasket 610 of the sealing body 600 are inserted into the positive electrode side insertion hole 420a. The lid 420 has a negative electrode side insertion hole 420b, which is a circular through-hole, at the other end in the longitudinal direction A. The insertion portion 320b of the negative electrode terminal 320 and the negative electrode side first gasket 630 of the sealing body 600 are inserted into the negative electrode side insertion hole 420b.

[0057] As shown in Figure 16, a circular recess 421 is formed on the upper surface of the lid 420, surrounding the negative electrode side insertion hole 420b. An annular pressing projection 422 is formed in the recess 421, projecting upward from the bottom surface of the recess 421. The circular recess 421, the annular pressing projection 422, and the negative electrode side insertion hole 420b are arranged concentrically. The recess 421 and the pressing projection 422 are formed by press-forming a flat plate-shaped member. As shown in Figure 20, the upper end surface of the pressing projection 422 is located on the busbar 32 side (i.e., above) the upper surface of the lid 420 against which the negative electrode side second gasket 640 abuts.

[0058] As shown in Figure 17, the lid 420 has a liquid injection insertion hole 420c formed by a circular through-hole between the positive electrode side insertion hole 420a and the negative electrode side insertion hole 420b. The insertion portion 440b of the sealing plug 440 is inserted into the liquid injection insertion hole 420c. The lid 420 is welded to the container 410. The lid 420 is made of, for example, aluminum or an aluminum alloy.

[0059] The cleavage valve 430 is provided on the lid 420, as shown in Figure 17. When the internal pressure of the battery 10 reaches a predetermined value, the cleavage valve 430 cleaves outward from the battery, allowing the internal pressure of the battery 10 to become atmospheric pressure. The cleavage valve 430 is formed, for example, in a circular shape. The cleavage valve 430 is formed to be thinner than the lid 420. The cleavage valve 430 has a groove that serves as a reference for cleavage. The cleavage valve 430 is formed integrally with the lid 420. The cleavage valve 430 may be formed separately from the lid 420 and then welded in an annular manner to a through hole provided in the lid 420.

[0060] As shown in Figure 12, the sealing plug 440 seals the liquid injection hole 420c of the lid 420. The sealing plug 440 is formed in a cylindrical shape. As shown in Figure 17, the sealing plug 440 includes a head 440a with a relatively large outer diameter and an insertion portion 440b that is continuous with the head 440a and has a relatively smaller outer diameter. The head 440a of the sealing plug 440 is welded to the lid 420. The insertion portion 440b is inserted into the liquid injection hole 420c. The sealing plug 440 is formed of, for example, aluminum or an aluminum alloy.

[0061] (Configuration of the insulator 500 of the battery 10) The insulator 500 insulates the components of the battery 10 from the outer casing 400. The insulator 500 shown in Figures 8 to 11, 16 and 18 includes an insulating cover 510, a positive electrode side insulating plate 520 and a negative electrode side insulating plate 530.

[0062] The insulating cover 510 covers the charge / discharge element 100. The insulating cover 510 exposes one side 100a of the charge / discharge element 100 to the outside, while covering the rest of the charge / discharge element 100. The insulating cover 510 is formed, for example, in a pentahedral shape and is constructed by folding into a box shape. The insulating cover 510 is made of, for example, polypropylene.

[0063] The positive electrode side insulating plate 520 insulates the positive electrode current collector plate 210 from the lid 420. The positive electrode side insulating plate 520 includes a rectangular plate-shaped base portion 520a, an insertion hole 520b that penetrates the base portion 520a, and a protrusion 520c that surrounds the side edge of the base portion 520a in an annular shape and protrudes away from the lid 420. The positive electrode current collector plate 210 is housed in the space formed by the base portion 520a and the protrusion 520c of the positive electrode side insulating plate 520. The insertion portion 310b of the positive electrode terminal 310 is inserted into the insertion hole 520b. The positive electrode side insulating plate 520 is formed of, for example, an insulating resin.

[0064] The negative electrode side insulating plate 530 is provided between the negative electrode current collector plate 220 and the lid 420. The negative electrode side insulating plate 530 insulates the negative electrode current collector plate 220 from the lid 420. The negative electrode side insulating plate 530 includes a rectangular plate-shaped base portion 530a, an insertion hole 530b that penetrates the base portion 530a, and a protrusion 530c that surrounds the side edge of the base portion 530a in an annular shape and protrudes away from the lid 420. The negative electrode current collector plate 220 is housed in the space formed by the base portion 530a and the protrusion 530c of the negative electrode side insulating plate 530. The insertion portion 320b of the negative electrode terminal 320 and the cylindrical portion 631 of the negative electrode side first gasket 630 are inserted into the insertion hole 530b. The negative electrode side insulating plate 530 is formed of, for example, an insulating resin.

[0065] As shown in Figure 20, the insertion hole 530b of the negative electrode side insulating plate 530 includes a large-diameter hole 530b1 into which the lower end of the cylindrical portion 631 of the negative electrode side first gasket 630 is inserted, and a small-diameter hole 530b2 into which the insertion portion 320b of the connection terminal 321 is inserted. The inner diameter of the large-diameter hole 530b1 is larger than the outer diameter of the cylindrical portion 631 of the negative electrode side first gasket 630. The inner diameter of the small-diameter hole 530b2 is smaller than the inner diameter of the large-diameter hole 530b1, and larger than the outer diameter of the insertion portion 320b of the connection terminal 321. A stepped surface 530b3, which is a surface perpendicular to the height direction Z, is formed between the large-diameter hole 530b1 and the small-diameter hole 530b2. The stepped surface 530b3 faces the lower end surface of the cylindrical portion 631 of the negative electrode side first gasket 630 in the height direction Z.

[0066] In this configuration, an annular projection 530d is formed so as to protrude radially inward from the inner circumferential surface of the large-diameter hole 530b1. Therefore, in this embodiment, the creepage distance between the cover 420 and the negative electrode current collector plate 220 can be increased compared to when the projection 530d is not formed. As a result, short circuits between the cover 420 and the negative electrode current collector plate 220 can be effectively suppressed.

[0067] A gap is formed between the inner circumferential surface of the large-diameter hole 530b1 of the negative electrode side insulating plate 530 and the outer circumferential surface of the cylindrical portion 631 of the negative electrode side first gasket 630. A gap is formed between the stepped surface 530b3 of the negative electrode side insulating plate 530 and the lower end surface of the cylindrical portion 631 of the negative electrode side first gasket 630. A gap is formed between the inner circumferential surface of the small-diameter hole 530b2 of the negative electrode side insulating plate 530 and the outer circumferential surface of the insertion portion 320b of the connection terminal 321.

[0068] (Configuration of the encapsulant 600 of the battery 10) The encapsulant 600 seals the components of the battery 10 and the outer casing 400. The encapsulant 600 shown in Figures 8 to 11, 16 and 18 includes a positive electrode side first gasket 610, a positive electrode side second gasket 620, a negative electrode side first gasket 630 and a negative electrode side second gasket 640.

[0069] The positive electrode side first gasket 610 seals the positive electrode current collector plate 210 and the cover 420, thereby sealing the outer casing 400. The positive electrode side first gasket 610 is formed in a cylindrical shape. As shown in Figure 18, the positive electrode side first gasket 610 includes a first insertion portion 610a with a relatively large outer diameter, a second insertion portion 610b that is continuous with the first insertion portion 610a and has a relatively smaller outer diameter, and an insertion hole 610c that penetrates the first insertion portion 610a and the second insertion portion 610b. As shown in Figure 11, the positive electrode side first gasket 610 is provided between the positive electrode terminal 310 and the positive electrode current collector plate 210. The first insertion portion 610a is inserted into the insertion hole 520b of the positive electrode side insulating plate 520 shown in Figure 18. The second insertion portion 610b is inserted into the positive electrode side insertion hole 420a of the lid 420 shown in Figure 18 and the insertion hole 620b of the positive electrode side second gasket 620. The insertion portion 310b of the positive electrode terminal 310 shown in Figure 18 is inserted into the insertion hole 610c. The positive electrode side first gasket 610 is formed of, for example, rubber that has insulating and elastic properties.

[0070] The positive electrode side second gasket 620 insulates and seals the positive electrode terminal 310 from the lid 420. As shown in Figure 18, the positive electrode side second gasket 620 includes a rectangular plate-shaped base portion 620a, an insertion hole 620b that penetrates the base portion 620a, and a protrusion 620c that surrounds the side edge of the base portion 620a in an annular shape and protrudes away from the lid 420. The positive electrode terminal 310 is housed in the space formed by the base portion 620a and the protrusion 620c of the positive electrode side second gasket 620. The insertion portion 310b of the positive electrode terminal 310 is inserted into the insertion hole 620b. The positive electrode side second gasket 620 is formed of, for example, an insulating resin.

[0071] As shown in Figures 19 to 21, the negative electrode side first gasket 630 is positioned between the lid 420 and the connection terminal 321 that penetrates the lid 420. The negative electrode side first gasket 630 seals the outer casing 400 by insulating and sealing the space between the lid 420 and the negative electrode terminal 320. The negative electrode side first gasket 630 is formed of, for example, rubber that has insulating and elastic properties. The negative electrode side first gasket 630 is pressed by the lid 420 and the negative electrode terminal 320, and fills the gap between the two members by elastic deformation. The negative electrode side first gasket 630 has a lower modulus of elasticity and is more easily deformed than the negative electrode side second gasket 640 and the negative electrode side insulating plate 530.

[0072] The negative electrode side first gasket 630 includes a cylindrical tubular portion 631 and an annular flange portion 632 provided at one end of the tubular portion 631. The negative electrode side first gasket 630 has an insertion hole 630c formed therethrough in the height direction Z. The flange portion 632 protrudes radially outward from the tubular portion 631. The tubular portion 631 protrudes toward the charge / discharge body 100 from the flange portion 632 and is inserted into the negative electrode side insertion hole 420b. The tubular portion 631 is positioned in the gap between the insertion portion 320b of the connection terminal 321 and the negative electrode side insertion hole 420b of the lid 420. The insertion portion 320b of the connection terminal 321 is inserted into the insertion hole 630c, and the tubular portion 631 is inserted into the negative electrode side insertion hole 420b of the lid 420. The inner circumferential surface of the insertion hole 630c of the cylindrical portion 631 is in close contact with the outer circumferential surface of the insertion portion 320b of the connection terminal 321. A gap is formed between the outer circumferential surface of the cylindrical portion 631 and the inner circumferential surface of the negative electrode side insertion hole 420b of the lid 420.

[0073] The flange portion 632 is positioned between the head portion 321a of the connecting terminal 321 and the recess 421 of the lid 420. The flange portion 632 includes a small-diameter portion 632a that contacts the lower surface of the head portion 321a of the connecting terminal 321 and the pressing projection 321d, and a large-diameter portion 632b that contacts the bottom surface of the recess 421 of the lid 420 and the pressing projection 422. The small-diameter portion 632a and the large-diameter portion 632b are formed concentrically. The outer diameter of the small-diameter portion 632a is smaller than the outer diameter of the large-diameter portion 632b.

[0074] The small-diameter portion 632a of the flange 632 is pressed downward by the pressing projection 321d of the connection terminal 321 described above, and is elastically deformed in Figures 20 and 21. In Figures 20 and 21, the outer shape of the small-diameter portion 632a before elastic deformation is shown by the dashed line DL1. The large-diameter portion 632b of the flange 632 is pressed upward by the pressing projection 422 of the cover 420 described above, and is elastically deformed in Figures 20 and 21. In Figures 20 and 21, the outer shape of the large-diameter portion 632b before elastic deformation is shown by the dashed line DL2. In this way, the flange 632 is pressed in the height direction Z (up and down direction in the illustration) by the connection terminal 321 and the cover 420. As a result, the flange portion 632 and the lower surface of the head portion 321a and the pressing projection 321d of the connecting terminal 321 are in close contact, and the flange portion 632 and the bottom surface of the recess 421 and the pressing projection 422 of the lid 420 are in close contact. Consequently, the space between the lid 420 and the negative terminal 320 is properly sealed. In this way, the flange portion 632 is sandwiched between the head portion 321a of the connecting terminal 321 and the lid 420, and functions as a sealing portion.

[0075] The negative electrode side second gasket 640 insulates and seals the space between the negative electrode terminal 320 and the cover 420. The negative electrode side second gasket 640 is formed of, for example, an insulating resin. As shown in Figure 16, the negative electrode side second gasket 640 includes a rectangular plate-shaped base portion 640a, an insertion hole 640b that penetrates the base portion 640a, and a protrusion 640c that surrounds the side edge of the base portion 640a in an annular shape and protrudes away from the cover 420. The base portion 320a of the negative electrode terminal 320 is housed in the space formed by the base portion 640a and the protrusion 640c of the negative electrode side second gasket 640. The flange portion 632 of the negative electrode side first gasket 630, which is attached to the insertion portion 320b of the negative electrode terminal 320, is inserted into the insertion hole 640b.

[0076] As shown in Figure 20, an annular recess 641 is formed on the upper surface of the base 640a of the negative electrode side second gasket 640. The recess 641 is a gap that suppresses interference caused by deformation or movement of the connection terminal 321 and the external terminal 322 in the height direction Z.

[0077] As described above, the negative electrode side second gasket 640 is provided with an annular recess 641. Therefore, in this embodiment, the contact area between the negative electrode side second gasket 640 and the negative electrode terminal 320 can be reduced compared to the case where the recess 641 is not provided. As a result, when the negative electrode side second gasket 640 and the negative electrode side first gasket 630 are sandwiched between the base 320a of the negative electrode terminal 320 and the cover 420, the reaction force acting from the negative electrode side second gasket 640 to the base 320a of the negative electrode terminal 320 can be reduced.

[0078] Furthermore, if a recess with an opening on the radially inward side is provided instead of the recess 641 having an inner side surface 641b, there is a risk that if condensation water enters the recess from the outside, the condensation water may reach the recess 421 of the lid 420 through the insertion hole 640b. In this embodiment, the negative electrode side second gasket 640 is in contact with the base 320a of the negative electrode terminal 320 radially inward from the inner side surface 641b. Therefore, even if condensation water enters the recess 641, it is possible to prevent the condensation water from reaching the insertion hole 640b.

[0079] The insertion hole 640b of the negative electrode side second gasket 640 includes a circular large-diameter hole 640b1 and a circular small-diameter hole 640b2 with a smaller inner diameter than the large-diameter hole 640b1. The large-diameter portion 632b of the flange portion 632 of the negative electrode side first gasket 630 is inserted into the large-diameter hole 640b1 of the negative electrode side second gasket 640. The small-diameter portion 632a of the flange portion 632 of the negative electrode side first gasket 630 is inserted into the small-diameter hole 640b2 of the negative electrode side second gasket 640. A gap is formed between the inner circumferential surface of the large-diameter hole 640b1 of the negative electrode side second gasket 640 and the outer circumferential surface of the large-diameter portion 632b of the flange portion 632 of the negative electrode side first gasket 630. A gap is formed between the inner circumferential surface of the small-diameter hole 640b2 of the negative electrode side second gasket 640 and the outer circumferential surface of the small-diameter portion 632a of the flange portion 632 of the negative electrode side first gasket 630.

[0080] As described above, the negative electrode side second gasket 640 has a large diameter hole 640b1 and a small diameter hole 640b2. Therefore, a stepped portion is formed in the insertion hole 640b of the negative electrode side second gasket 640. Also, as described above, the flange portion 632 of the negative electrode side first gasket 630 has a small diameter portion 632a and a large diameter portion 632b. Therefore, a stepped portion is formed on the outer circumferential surface of the flange portion 632 of the negative electrode side first gasket 630. Thus, in this embodiment, stepped portions are formed on the negative electrode side first gasket 630 and the negative electrode side second gasket 640 so as to face each other. Therefore, in this embodiment, the creepage distance between the lid 420 and the base portion 320a of the negative electrode terminal 320 can be increased compared to when no stepped portion is formed. As a result, short circuits between the lid 420 and the negative electrode terminal 320 can be effectively suppressed.

[0081] The negative electrode side first gasket 630 described above is elastically deformed as it is sandwiched between the connection terminal 321 and the cover 420. The negative electrode side second gasket 640 is also sandwiched between the connection terminal 321 and the cover 420, but it hardly undergoes any elastic deformation. For this reason, when the components such as the negative electrode terminal 320 are mounted on the cover 420, the elastic reaction force acting from the negative electrode side second gasket 640 to the negative electrode terminal 320 is smaller than the elastic reaction force acting from the negative electrode side first gasket 630 to the negative electrode terminal 320.

[0082] The negative electrode side first gasket 630 is sandwiched between the negative electrode terminal 320 and the cover 420 and undergoes elastic deformation. This ensures proper sealing between the negative electrode terminal 320 and the cover 420. In this embodiment, as shown in Figure 19, the diameter φD of the annular laser joint portion 323 is larger than the diameter φd of the small diameter portion 632a of the flange portion 632 (φD > φd). The diameter (diameter) φD of the laser joint portion 323 corresponds to the diameter of the small diameter hole 322a2 of the insertion hole 322a, that is, the diameter of the small diameter portion 321a3 of the head 321a. The diameter (diameter) φd of the small diameter portion 632a corresponds to the maximum diameter of the portion of the flange portion 632 that is in contact with the head 321a of the connecting terminal 321.

[0083] When the negative electrode terminal 320 is crimped to the negative electrode current collector plate 220 and assembled to the cover 420, an upward elastic reaction force acts on the base 320a of the negative electrode terminal 320 (the head 321a of the connection terminal 321) from the flange 632 of the negative electrode side first gasket 630. Here, if the diameter φD of the laser joint 323 is smaller than the diameter φd of the small diameter portion 632a of the flange 632, the elastic reaction force of the negative electrode side first gasket 630 will also act on the external terminal 322. Since the connection terminal 321 is fixed to the negative electrode current collector plate 220, when an upward force (elastic reaction force of the negative electrode side first gasket 630) acts on the external terminal 322, shear stress is generated in the laser joint 323.

[0084] In contrast, in this embodiment, as described above, the diameter φD of the laser joint portion 323 is larger than the diameter φd of the small diameter portion 632a of the flange portion 632. Therefore, the elastic reaction force of the negative electrode side first gasket 630 acts only on the connection terminal 321. As a result, it is possible to prevent shear stress caused by the elastic reaction force of the negative electrode side first gasket 630 from occurring in the laser joint portion 323.

[0085] Furthermore, it is more preferable that the distance (shortest distance) from the central axis of the insertion hole 322a of the external terminal 322 to the inner edge of the annular laser joint portion 323 is greater than the radius (φd / 2) of the small diameter portion 632a of the flange portion 632 of the negative electrode side first gasket 630. In this configuration, the small diameter portion 632a does not come into contact with the laser joint portion 323. This prevents the elastic reaction force from directly acting on the laser joint portion 323.

[0086] (Configuration of the holding unit 20 of the battery pack 1) The holding unit 20 holds a plurality of batteries 10, as shown in Figures 1 to 5. The holding unit 20 includes a first end spacer 21P, a cell spacer 22, and a second end spacer 21Q, as shown in Figure 5. The holding unit 20 also includes a first end block 23P, a second end block 23Q, an insulating member 24, and an insert nut 25. The holding unit 20 also includes a first side plate 26P, a second side plate 26Q, and fastening bolts 27, as shown in Figure 4. The configuration included in the holding unit 20 will be described below.

[0087] The first end spacer 21P is provided between the first end block 23P and the battery 10, as shown in Figure 5. The first end spacer 21P is in contact with the first battery 10 located at one end of the 20 stacked batteries 10. This battery 10 corresponds to the battery 10 located at the left end in Figure 3. The first end spacer 21P insulates the first end block 23P from the battery 10. The first end spacer 21P covers each side of the first end block 23P and the battery 10 along the width direction Y. The first end spacer 21P covers a portion of the side 10b of the battery 10 along the stacking direction X. The thickness of the first end spacer 21P along the stacking direction X is sufficiently thinner than the thickness of the battery 10 along the stacking direction X. The first end spacer 21P is made of an insulating material.

[0088] As shown in Figure 5, the cell spacer 22 is provided between adjacent batteries 10. The cell spacer 22 holds and insulates the adjacent batteries 10. The cell spacer 22 covers a portion of each main surface 10c along the width direction Y of the adjacent batteries 10 and a portion of each side surface 10b along the stacking direction X of the adjacent batteries 10. The thickness of the cell spacer 22 along the stacking direction X is sufficiently thinner than the thickness of the batteries 10 along the stacking direction X. The cell spacer 22 is made of an insulating material.

[0089] The second end spacer 21Q is located between the battery 10 and the second end block 23Q, as shown in Figure 5. The second end spacer 21Q is in contact with the 20th battery 10, which is located at the other end of the stacked 20 batteries 10. This battery 10 corresponds to the battery 10 located at the right end in Figure 3. The second end spacer 21Q insulates the battery 10 from the second end block 23Q. The second end spacer 21Q covers each side of the first end block 23P and the battery 10 along the width direction Y. The second end spacer 21Q covers a portion of the side 10b of the battery 10 along the stacking direction X. The thickness of the second end spacer 21Q along the stacking direction X is sufficiently thinner than the thickness of the battery 10 along the stacking direction X. The second end spacer 21Q is made of an insulating material.

[0090] As shown in Figure 5, the first end block 23P is stacked with the first battery 10 located at one end of the stacked 20 batteries 10, via a first end spacer 21P. The first end block 23P extends along the width direction Y, which intersects the stacking direction X of the batteries 10. The first end block 23P is adjacent to the battery 10 located at the end along the stacking direction X and supports the battery 10. The first end block 23P is formed in a rectangular parallelepiped shape extending in the width direction Y. Fastening bolts 27 are screwed into a plurality of screw holes 23Pa formed on the side surface of the first end block 23P along the width direction Y, as shown in Figure 4. As shown in Figure 1, the first end block 23P is fixed to the first side plate 26P by fastening bolts 27. Similarly, the first end block 23P is fixed to the second side plate 26Q by fastening bolts 27. The first end block 23P has insertion holes 23Pc for inserting bolts, etc., for fixing the battery pack 1. The first end block 23P is formed of, for example, metal or resin.

[0091] As shown in Figure 5, the second end block 23Q is stacked with the 20th battery 10 located at the other end of the stacked 20 batteries 10, via a second end spacer 21Q. The second end block 23Q extends along the width direction Y of the battery 10. The second end block 23Q is adjacent to the battery 10 located at the end along the stacking direction X and supports the battery 10. The second end block 23Q is formed in a rectangular parallelepiped shape extending in the width direction Y. Fastening bolts 27 are screwed into a plurality of screw holes formed on the side surface of the second end block 23Q along the width direction Y, as shown in Figure 4. As shown in Figure 1, the second end block 23Q is fixed to the first side plate 26P by fastening bolts 27. Similarly, the second end block 23Q is fixed to the second side plate 26Q by fastening bolts 27. The second end block 23Q has an insertion hole 23Qc formed therein for inserting bolts, etc., for fixing the battery pack 1. The second end block 23Q is formed of, for example, metal or resin.

[0092] As shown in Figure 5, the insulating member 24 is inserted into the first end block 23P. The insulating member 24 is also inserted into the second end block 23Q. The insulating member 24 is formed, for example, in a rectangular shape. The insulating member 24 is made of an insulating material.

[0093] The insulating member 24 may have the following configuration. That is, the insulating member 24 may be molded integrally with the first end spacer 21P, or it may be molded separately from the first end spacer 21P and then joined to the first end spacer 21P. In such cases, the first end block 23P is provided with a recess on the surface facing the first end spacer 21P for accommodating the insulating member 24 along the stacking direction X. Similarly, the insulating member 24 may be molded integrally with the second end spacer 21Q, or it may be molded separately from the second end spacer 21Q and then joined to the second end spacer 21Q. In such cases, the second end block 23Q is provided with a recess on the surface facing the second end spacer 21Q for accommodating the insulating member 24 along the stacking direction X.

[0094] As shown in Figure 4, the insert nut 25 is embedded in a recess formed on the upper surface of the insulating member 24. The fastening bolt is secured to the insert nut 25, for example, via a busbar that is electrically connected to an external control device.

[0095] As shown in Figure 1, the first side plate 26P is positioned along the stacking direction X of the stacked batteries 10, and at one end of the batteries 10 in the width direction Y. The first side plate 26P holds the batteries 10 along the stacking direction X. Both ends of the first side plate 26P that extend along the stacking direction X are bent toward the width direction Y. As shown in Figure 4, fastening bolts 27 are inserted into a plurality of insertion holes 26Pa formed on the side surface of the first side plate 26P along the width direction Y. As shown in Figure 1, the first side plate 26P is fixed to the first end block 23P and the second end block 23Q by fastening bolts 27.

[0096] As shown in Figure 1, the second side plate 26Q is positioned along the stacking direction X of the stacked batteries 10, and at the other end of the batteries 10 in the width direction Y. The second side plate 26Q holds the batteries 10 along the stacking direction X. Both ends of the second side plate 26Q extending along the stacking direction X are bent toward the width direction Y. As shown in Figure 4, fastening bolts 27 are inserted into a plurality of insertion holes 26Qa formed on the side surface of the second side plate 26Q along the width direction Y. As shown in Figure 1, the second side plate 26Q is fixed to the first end block 23P and the second end block 23Q by fastening bolts 27.

[0097] As shown in Figure 3, the fastening bolts 27 fasten the first side plate 26P to the first end block 23P, and the first side plate 26P to the second end block 23Q. Also, as shown in Figure 3, the fastening bolts 27 fasten the second side plate 26Q to the first end block 23P, and the second side plate 26Q to the second end block 23Q.

[0098] (Configuration of the busbar unit 30 of the battery pack 1) The busbar unit 30 shown in Figures 1, 3, and 6 electrically connects multiple batteries 10. As shown in Figure 6, the busbar unit 30 includes a first end busbar 31, multiple busbars 32, a second end busbar 33, and a busbar holder 34. The configuration included in the busbar unit 30 will be described below.

[0099] As shown in Figure 3, the first end busbar 31 is joined to the positive terminal 310 of the battery 10 closest to the first end block 23P among the 20 stacked batteries 10. As shown in Figure 6, the first end busbar 31 includes a plate-shaped first joint portion 31a, a plate-shaped second joint portion 31b, a curved connecting portion 31c, and an insertion hole 31d. The first joint portion 31a is joined to a busbar that is electrically connected to an external control device. The second joint portion 31b is joined to the positive terminal 310 of the battery 10. The connecting portion 31c connects the first joint portion 31a and the second joint portion 31b. The insertion hole 31d is formed in the first joint portion 31a. A fastening bolt is inserted into the insertion hole 31d. The first joint portion 31a and the busbar that is electrically connected to the external control device are joined by the fastening bolt. The first end busbar 31 is made of, for example, aluminum. If the first end busbar 31 is formed of a clad material, for example, the first joint portion 31a is formed of copper and the second joint portion 31b is formed of aluminum. If the negative terminal 320 of the battery 10 is converted from copper to aluminum, the first end busbar 31 may be configured such that the first joint portion 31a and the second joint portion 31b are integrally formed of aluminum.

[0100] As shown in Figure 3, the busbar 32 electrically connects one adjacent battery 10 to another battery 10 along the stacking direction X. As shown in Figure 3, the busbar 32 is joined to the positive terminal 310 of one adjacent battery 10 along the stacking direction X and to the negative terminal 320 of the other adjacent battery 10 along the stacking direction X. As shown in Figure 6, the busbar 32 includes a plate-shaped first joint portion 32a, a plate-shaped second joint portion 32b, and a curved connecting portion 32c. The first joint portion 32a is joined to the negative terminal 320 of one adjacent battery 10. The second joint portion 32b is joined to the positive terminal 310 of the other adjacent battery 10. The connecting portion 32c connects the first joint portion 32a and the second joint portion 32b. The busbar 32 is formed from, for example, a clad material of copper and aluminum, copper, or aluminum. If the busbar 32 is formed of a clad material, for example, the first joint portion 32a is made of copper and the second joint portion 32b is made of aluminum. If the negative terminal 320 of the battery 10 is converted from copper to aluminum, the busbar 32 may be configured such that the first joint portion 32a, the second joint portion 32b, and the connecting portion 32c are integrally formed from aluminum.

[0101] As shown in Figure 3, the second end busbar 33 is joined to the negative terminal 320 of the battery 10 closest to the second end block 23Q among the 20 stacked batteries 10. As shown in Figure 6, the second end busbar 33 includes a plate-shaped first joint portion 33a, a plate-shaped second joint portion 33b, a curved connecting portion 33c, and an insertion hole 33d. The first joint portion 33a is joined to the negative terminal 320 of the battery 10. The second joint portion 33b is joined to a busbar that is electrically connected to an external control device. The connecting portion 33c connects the first joint portion 33a and the second joint portion 33b. The insertion hole 33d is formed in the second joint portion 33b. A fastening bolt is inserted into the insertion hole 33d. The second joint portion 33b and the busbar that is electrically connected to the external control device are joined by the fastening bolt. The second end busbar 33 is made of, for example, copper.

[0102] As shown in Figure 1, the busbar holder 34 integrally holds the first end busbar 31, the multiple busbars 32, and the second end busbar 33. The busbar holder 34 also covers and insulates the multiple stacked batteries 10. As shown in Figure 6, the busbar holder 34 is formed in a plate shape. The busbar holder 34 has multiple openings 34a. Each opening 34a exposes the first or second joint of the first end busbar 31, the multiple busbars 32, and the second end busbar 33 toward the battery 10. Each opening 34a is larger than the first or second joint of the corresponding busbar. The busbar holder 34 has multiple holding portions 34b. Each holding portion 34b holds the ends of the first or second joints of the first end busbar 31, the multiple busbars 32, and the second end busbar 33. Each retaining portion 34b is formed on the edge of the opening 34a. Each retaining portion 34b has a linear groove along the surface of the busbar holder 34. The end of the first or second joint of the corresponding busbar is inserted into the groove provided in each retaining portion 34b. The busbar holder 34 has a plurality of insertion portions 34c. The wires 52 of the temperature measuring unit 50 are inserted into the insertion portions 34c.

[0103] (Configuration of the voltage detection unit 40 of the battery pack 1) The voltage detection unit 40 shown in Figures 1, 3, and 6 detects the voltage of the battery 10, for example, based on control by an external control device. As shown in Figure 6, the voltage detection unit 40 includes a voltage detection terminal 41 and an electric wire 42. The configuration included in the voltage detection unit 40 will be described below.

[0104] As shown in Figure 6, the voltage detection terminal 41 is conductive and formed in a plate shape. The voltage detection terminal 41 is joined to the first end busbar 31, the multiple busbars 32, and the second end busbar 33 of the busbar unit 30, respectively.

[0105] As shown in Figure 6, the electric wire 42 is connected to the voltage detection terminal 41. The electric wire 42 provides electrical conductivity between the voltage detection terminal 41 and the external control equipment.

[0106] (Configuration of the temperature measuring unit 50 of the battery pack 1) The temperature measuring unit 50 shown in Figures 1, 3, and 6 measures the temperature of the battery 10, for example, based on control by an external control device. As shown in Figure 3, the temperature measuring unit 50 includes a temperature sensor 51 and an electric wire 52. The configuration included in the temperature measuring unit 50 will be described below.

[0107] The temperature sensor 51 measures the temperature of the battery 10. As shown in Figure 3, the temperature sensor 51 is, for example, bonded to the lid 420 of the battery 10, which is located at the 7th and 14th positions from the first end block 23P toward the second end block 23Q.

[0108] As shown in Figure 3, the electric wire 52 is attached to the temperature sensor 51. The electric wire 52 provides electrical conductivity between the temperature sensor 51 and the external control equipment.

[0109] (Configuration of the gas exhaust unit 60 of the battery pack 1) The gas exhaust unit 60 shown in Figure 1 discharges the gas emitted from the battery 10 to the outside of the battery pack 1. As shown in Figure 1, the gas exhaust unit 60 includes a gas duct 61 and fastening bolts 62. The components included in the gas exhaust unit 60 will be described below.

[0110] As shown in Figure 8, the gas duct 61 includes a gas transfer section 61a, a gas discharge section 61b, and a fixed section 61c. The gas transfer section 61a extends along the stacking direction X. The gas transfer section 61a is formed in a rectangular shape and has a space along its longitudinal direction. The gas transfer section 61a faces the cleavage valves 430 of the stacked 20 batteries 10 through the space. The gas transfer section 61a covers the cleavage valves 430 of the stacked 20 batteries 10 and moves the gas discharged from the cleavage valves 430 toward the gas discharge section 61b. As shown in Figure 8, the gas discharge section 61b opens at one end of the gas transfer section 61a in the longitudinal direction. The gas discharge section 61b is formed in a cylindrical shape. The gas discharge section 61b discharges the gas accumulated in the gas transfer section 61a to the outside. The gas discharge section 61b may be configured to connect to a hose for discharging the gas. As shown in Figure 8, the fixing portions 61c are formed at both ends in the longitudinal direction of the gas transfer portion 61a. The pair of fixing portions 61c are formed in a plate shape. The pair of fixing portions 61c have holes for inserting fastening bolts 62.

[0111] As shown in Figure 4, the fastening bolt 62 secures the gas duct 61 to the threaded hole 23Pb of the first end block 23P via the fixing portion 61c. Similarly, the fastening bolt 62 secures the gas duct 61 to the threaded hole 23Qb of the second end block 23Q via the fixing portion 61c.

[0112] (Effects of the battery 10 and battery pack 1 of the first embodiment) The effects of the battery 10 and battery pack 1 of the first embodiment will be described.

[0113] (1) The battery 10 comprises a charge / discharge element 100, an outer casing 400 housing the charge / discharge element 100, a negative electrode terminal (electrode terminal) 320 that penetrates the outer casing 400 and is electrically connected to the charge / discharge element 100, and a sealing element 600 that insulates and seals the space between the outer casing 400 and the negative electrode terminal 320. The negative electrode terminal 320, which is an electrode terminal, has a connection terminal 321 and an external terminal 322, as shown in Figures 20 and 21. The connection terminal 321 is electrically connected to the charge / discharge element 100. The external terminal 322 has an insertion hole 322a into which the connection terminal 321 is inserted and which contacts the outer edge of the connection terminal 321. The external terminal 322 has a first member 322x and a second member 322y. The first member 322x is laser-bonded to the connection terminal 321. The second member 322y is laminated on the first member 322x and solid-state bonded to the first member 322x. The first member 322x and the connection terminal 321 of the external terminal 322 contain a first metal. The second member 322y of the external terminal 322 contains a second metal made of a different material than the first metal. The connection terminal 321 includes a head 321a inserted into the insertion hole 322a of the external terminal 322, and an insertion portion 320b that protrudes from the head 321a toward the charge / discharge body 100 and penetrates the negative electrode side insertion hole (through hole) 420b of the outer casing 400. The sealing body 600 includes a flange portion (seal portion) 632 of the negative electrode side first gasket 630 sandwiched between the head 321a of the connection terminal 321 and the outer casing 400. A laser-jointed portion 323 is formed by laser joining the inner edge of the insertion hole 322a of the external terminal 322 and the outer edge of the head 321a of the connecting terminal 321. The laser-jointed portion 323 is formed in an annular shape along the inner edge of the insertion hole 322a. The diameter φD of the annular laser-jointed portion 323 is larger than the maximum diameter φd of the portion of the flange 632 that is in contact with the head 321a.

[0114] With this configuration, when assembling the negative electrode terminal 320 to the lid 420 while elastically deforming the flange 632 of the negative electrode side first gasket 630, it is possible to prevent shear stress caused by the elastic reaction force of the flange 632 of the negative electrode side first gasket 630 from occurring in the laser joint 323. Therefore, according to this embodiment, a battery 10 can be obtained that can suppress damage to the laser joint 323.

[0115] (2) Around the insertion hole 322a, the second member 322y is positioned further away from the charge / discharge body 100 than the first member 322x. This configuration can suppress damage to the laser joint 323 formed on the lid 420 side of the head 321a.

[0116] (4) The external terminal 322 includes a fitting recess (recess) 322a4 that is recessed opposite to the connection terminal 321. The connection terminal 321 includes a fitting projection (projection) 321a5 that protrudes toward the external terminal 322. The fitting recess 322a4 and the fitting projection 321a5 are in contact in the stacking direction (height direction Z) of the first member 322x and the second member 322y.

[0117] With this configuration, the fitting recess 322a4 and the fitting projection 321a5 come into contact in the central axis direction (height direction Z) of the insertion hole 322a, thereby restricting the positions of the connection terminal 321 and the external terminal 322 in the height direction Z. In other words, by fitting the fitting recess 322a4 and the fitting projection 321a5 together, the positioning that is performed prior to the laser bonding process between the connection terminal 321 and the external terminal 322 can be easily carried out.

[0118] (5) The end face 321a1 of the connection terminal 321 opposite to the side on which the charge / discharge element 100 is located is located closer to the charge / discharge element 100 than the end face (terminal face 322b) of the external terminal 322 opposite to the side on which the charge / discharge element 100 is located. With this configuration, the busbar 32 and the external terminal 322 can be overlapped and welded together with the busbar 32 in contact with the terminal face 322b of the external terminal 322.

[0119] (6) The first metal is a metal mainly composed of copper. The second metal is a metal mainly composed of aluminum. This makes it possible to easily and appropriately laser bond the busbar 32, which is mainly composed of aluminum, to the second member 322y of the negative electrode terminal 320.

[0120] (7) As shown in Figures 1 to 3, the battery pack 1 includes the battery 10 described above and a busbar 32 connected to the negative electrode terminal (electrode terminal) 320. Therefore, according to this embodiment, it is possible to provide a battery pack 1 that can suppress damage to the laser bonding portion 323.

[0121] (A) The rectangular flat first member 322x is solid-state bonded to a portion of the lid 420 side surface of the rectangular flat second member 322y. The first member 322x is laminated on the second member 322y around the insertion hole 322a. The external terminals 322 are formed from inlay-type or edge-lay-type cladding material (i.e., partial cladding material). With this configuration, the amount of copper-based material used in the external terminals 322 is reduced, thus making it possible to reduce the cost of the battery 10.

[0122] (B) In the fitting recess 322a4, the surface (step surface 322a3) that contacts the fitting projection 321a5 in the stacking direction (height direction Z) is provided on the second member 322y. With this configuration, both the insertion hole 322a and the fitting recess 322a4 can be formed by hole processing such as cold forging or press working. In other words, the hole processing of the external terminal 322 can be easily performed, resulting in good manufacturability of the external terminal 322.

[0123] (Battery pack 1 of modification 1 of the first embodiment) The battery pack 1 of modification 1 of the first embodiment has a negative electrode terminal 1120 as shown in Figure 22.

[0124] (Configuration of the negative electrode terminal 1120) The configuration of the negative electrode terminal 1120 will be described with reference to Figure 22. Figure 22 is an enlarged side view showing the cross-section of the negative electrode terminal 1120 and its surrounding components in a modified example 1 of the first embodiment.

[0125] In Modification 1 of the First Embodiment, components identical to those in the First Embodiment are given the same reference numerals as in the First Embodiment and their descriptions are omitted. In Modification 1 of the First Embodiment, components different from those in the First Embodiment are given different reference numerals and described accordingly.

[0126] In the first embodiment, as shown in Figures 20 and 21, the end face 321a1 of the negative terminal 320 on the busbar 32 side is located closer to the cover 420 (the lower side in Figures 20 and 21) than the terminal face 322b of the external terminal 322. For this reason, in the first embodiment, a recess 320d is provided on the end face of the negative terminal 320 on the busbar 32 side.

[0127] In contrast, in the first modified example of the first embodiment, as shown in Figure 22, there is no recess on the end face of the negative terminal 1120 on the busbar 32 side. The end face 1121a1 of the connecting terminal 1121 on the busbar 32 side is flush with the terminal face 322b of the external terminal 322 and along the cover 420.

[0128] (Effects of the battery 10 and battery pack 1 in Modification 1 of the First Embodiment) The effects of the battery 10 and battery pack 1 in Modification 1 of the First Embodiment will be described. According to Modification 1 of the First Embodiment, the effects of (1), (2), (4), (6), (7), (A), and (B) described in the First Embodiment can be obtained.

[0129] (Battery pack 1 of modification 2 of the first embodiment) The battery pack 1 of modification 2 of the first embodiment has a negative electrode terminal 1220 as shown in Figure 23.

[0130] (Configuration of the negative electrode terminal 1220) The configuration of the negative electrode terminal 1220 will be described with reference to Figure 23. Figure 23 is an enlarged side view showing the cross-section of the negative electrode terminal 1220 and its surrounding components in a modified example 2 of the first embodiment.

[0131] In Modification 2 of the First Embodiment, components identical to those in the First Embodiment are given the same reference numerals as in the First Embodiment and their descriptions are omitted. In Modification 2 of the First Embodiment, components different from those in the First Embodiment are given different reference numerals and described accordingly.

[0132] In the first embodiment, an example was described in which the external terminal 322 is formed of an inlay-type or edge-lay-type cladding material. In the first embodiment, as shown in Figures 20 and 21, the first member 322x is laminated on the second member 322y only around the insertion hole 322a.

[0133] In contrast, in the modified example 2 of the first embodiment, the external terminal 1222 is formed of a so-called overlay-type cladding material, as shown in Figure 23. The rectangular flat plate-shaped first member 1222x is solid-state bonded to the entire surface of the lid 420 side of the rectangular flat plate-shaped second member 1222y.

[0134] (Effects of the Battery 10 and Battery Pack 1 in Modification 2 of the First Embodiment) The effects of the Battery 10 and Battery Pack 1 in Modification 2 of the First Embodiment will be described. According to Modification 2 of the First Embodiment, the effects of (1), (2), (4) to (7), and (B) described in the First Embodiment can be obtained.

[0135] Furthermore, in the modified example 2 of the first embodiment, there is no step between the rectangular flat first member 1222x and the rectangular flat second member 1222y, making manufacturing relatively easy.

[0136] (Battery pack 1 of the second embodiment) The battery pack 1 of the second embodiment has a negative terminal 1320 as shown in Figure 24.

[0137] (Configuration of the negative electrode terminal 1320) The configuration of the negative electrode terminal 1320 will be described with reference to Figure 24. Figure 24 is an enlarged side view showing the cross-section of the negative electrode terminal 1320 of the second embodiment and the surrounding components.

[0138] In the second embodiment, components identical to those in the first embodiment are given the same reference numerals as in the first embodiment and their descriptions are omitted. In the second embodiment, components different from those in the first embodiment are described using different reference numerals.

[0139] In the first embodiment, as shown in Figures 20 and 21, a fitting recess 322a4 and a fitting projection 321a5 are provided on the inner circumferential surface of the insertion hole 322a of the external terminal 322 and on the outer circumferential surface of the head 321a of the connecting terminal 321, respectively, as fitting portions that fit together.

[0140] In contrast, in the second embodiment, as shown in Figure 24, there are no fitting portions that engage with each other on the inner circumferential surface of the insertion hole 1322a of the external terminal 1322 and the outer circumferential surface of the head 1321a of the connecting terminal 1321. That is, there are no interlocking protrusions or recesses that engage with each other on the outer circumferential surface of the head 1321a of the connecting terminal 1321 and the inner circumferential surface of the insertion hole 1322a of the external terminal 1322, extending from one end of the insertion hole 1322a to the other.

[0141] (Effects of the Battery 10 and Battery Pack 1 of the Second Embodiment) The effects of the Battery 10 and Battery Pack 1 of the second embodiment will be described below. According to this second embodiment, the effects of (1), (2), (5) to (7), and (A) described in the first embodiment can be obtained.

[0142] Furthermore, in the second embodiment, the connection terminal 1321 can be inserted into the insertion hole 1322a of the external terminal 1322 from either one end or the other end of the insertion hole 1322a. This improves the flexibility of the workability when laser bonding the connection terminal 1321 and the external terminal 1322.

[0143] Furthermore, regardless of the component tolerances of the connection terminal 1321 and the external terminal 1322, the relative height Z position of the connection terminal 1321 and the external terminal 1322 can be adjusted to perform laser bonding at the desired position. For example, even if there is a dimensional difference between the connection terminal 1321 and the external terminal 1322, the height Z positioning of the connection terminal 1321 and the external terminal 1322 can be adjusted so that the lower end surface of the head 1321a of the connection terminal 1321 and the lower end surface of the external terminal 1322 are flush. This ensures that a good laser-bonded portion 323 can be obtained even if there are component tolerances.

[0144] Furthermore, even if the thickness of the head portion 1321a of the connection terminal 1321 is greater than the design dimension, the connection terminal 1321 and the external terminal 1322 can be positioned in the height direction Z such that the end face 1321a1 of the connection terminal 1321 is located closer to the cover 420 than the terminal face 1322b of the external terminal 1322. This ensures that the connection terminal 1321 does not interfere with the busbar 32.

[0145] (Battery pack 1 of modification 1 of the second embodiment) In the second embodiment, as shown in Figure 24, the end face 1321a1 of the negative terminal 1320 on the busbar 32 side is located below the terminal face 1322b of the external terminal 1322. In contrast, in modification 1 of the second embodiment, although not shown, the end face 1321a1 of the connection terminal 1321 on the busbar 32 side is flush with the terminal face 1322b of the external terminal 1322 along the cover 420.

[0146] (Effects of the Battery 10 and Battery Pack 1 in Modification 1 of the Second Embodiment) The effects of the Battery 10 and Battery Pack 1 in Modification 1 of the Second Embodiment will be described. According to Modification 1 of the Second Embodiment, the effects of (1), (2), (6), (7), and (A) described in the First Embodiment can be obtained.

[0147] Furthermore, in the modified example 1 of the second embodiment, similar to the second embodiment, regardless of the component tolerances of the connection terminal 1321 and the external terminal 1322, the relative height Z position between the connection terminal 1321 and the external terminal 1322 can be adjusted to enable laser bonding at a desired position.

[0148] (Modified Battery Pack 1 of the Second Embodiment 2) In the second embodiment, an example was described in which the external terminal 1322 is formed of an inlay-type or edge-lay-type cladding material. However, the external terminal 1322 may also be formed of a so-called overlay-type cladding material. That is, in Modified Battery Pack 2 of the second embodiment, although not shown, the rectangular flat first member and the second member are solid-state bonded over the entire surface of their opposing surfaces.

[0149] (Effects of the Battery 10 and Battery Pack 1 in Modification 2 of the Second Embodiment) The effects of the Battery 10 and Battery Pack 1 in Modification 2 of the Second Embodiment will be described. According to Modification 2 of the Second Embodiment, the effects (1), (2), (5) to (7) described in the First Embodiment can be obtained.

[0150] Furthermore, in the modified version 2 of the second embodiment, similar to the second embodiment, regardless of the component tolerances of the connection terminal 1321 and the external terminal 1322, the relative height Z position between the connection terminal 1321 and the external terminal 1322 can be adjusted to enable laser bonding at a desired position. Moreover, if the overlay-type cladding material is easier to procure than the inlay-type or edge-lay-type cladding material, the lead time for procuring materials for the battery 10 can be shortened.

[0151] (Battery pack 1 of the third embodiment) The battery pack 1 of the third embodiment has a negative terminal 1420 as shown in Figure 25.

[0152] (Configuration of the negative electrode terminal 1420) The configuration of the negative electrode terminal 1420 will be described with reference to Figure 25. Figure 25 is an enlarged side view showing the cross-section of the negative electrode terminal 1420 of the third embodiment and the surrounding components.

[0153] In the third embodiment, components identical to those in the first embodiment are given the same reference numerals as in the first embodiment and their descriptions are omitted. In the third embodiment, components different from those in the first embodiment are described using different reference numerals.

[0154] In the first embodiment, as shown in Figures 20 and 21, the second member 322y is positioned further away from the charge / discharge body 100 than the first member 322x around the insertion hole 322a. That is, the first member 322x is solid-state bonded to the lid 420 side surface of the second member 322y. The laser bonding portion 323 is formed on the lid 420 side of the head portion 321a.

[0155] In contrast, in the third embodiment, as shown in Figure 25, the first member 1422x is located further away from the charge / discharge body 100 than the second member 1422y around the insertion hole 1422a. In other words, the first member 1422x is solid-state bonded to the busbar 32 side surface of the second member 1422y.

[0156] Furthermore, in the first embodiment, as shown in Figures 20 and 21, a fitting recess 322a4 was provided on the busbar 32 side surface of the external terminal 322, and a fitting projection 321a5 was provided on the busbar 32 side end of the connecting terminal 321. In contrast, in the third embodiment, as shown in Figure 25, a fitting recess 1422a4 was provided on the cover 420 side surface of the external terminal 1422, and a fitting projection 1421a5 was provided on the cover 420 side end of the head 1421a of the connecting terminal 1421.

[0157] The inner circumferential surface of the insertion hole 1422a of the external terminal 1422 is provided with a fitting recess 1422a4 that is recessed radially outward from the insertion hole 1422a. The outer circumferential surface of the head 1421a of the connecting terminal 1421 is provided with a fitting projection 1421a5 that protrudes radially outward from the insertion hole 1422a. The fitting recess 1422a4 of the external terminal 1422 is a recess recessed opposite to the outer circumferential surface of the head 1421a of the connecting terminal 1421. The fitting projection 1421a5 of the connecting terminal 1421 is a projection that protrudes toward the external terminal 1422. The fitting projection 1421a5 and the fitting recess 1422a4 are in contact at least in the stacking direction (height direction Z) of the first member 1422x and the second member 1422y.

[0158] As described above, in this embodiment, a fitting recess 1422a4 and a fitting projection 1421a5 are provided on the inner circumferential surface of the insertion hole 1422a of the external terminal 1422 and the outer circumferential surface of the head 1421a of the connecting terminal 1421, respectively, as fitting portions that fit together and are in contact with each other. The stepped surface 1422a3 of the fitting recess 1422a4 and the stepped surface 1421a4 of the fitting projection 1421a5 are in contact, thereby defining the positions of the external terminal 1422 and the connecting terminal 1421 in the height direction Z. For this reason, the fitting recess 1422a4 and the fitting projection 1421a5 can be used to position the external terminal 1422 and the connecting terminal 1421 in the height direction Z.

[0159] (Effects of the Battery 10 and Battery Pack 1 of the Third Embodiment) The effects of the Battery 10 and Battery Pack 1 of the third embodiment will be described. According to this third embodiment, the effects (1), (4) to (7), (A), and (B) described in the first embodiment can be obtained.

[0160] Furthermore, in the third embodiment, the end face 1421a1 of the connection terminal 1421 is located closer to the charge / discharge body 100 than the terminal face 1422b of the external terminal 1422. This configuration effectively prevents the laser bonding portion 1423 formed on the busbar 32 side of the head portion 1421a from interfering with the busbar 32.

[0161] (Battery pack 1 of modification 1 of the third embodiment) In the third embodiment, as shown in Figure 25, the end face 1421a1 of the negative terminal 1420 on the busbar 32 side was located below the terminal face 1422b of the external terminal 1422. In contrast, in modification 1 of the third embodiment, although not shown, the end face 1421a1 of the connecting terminal 1421 on the busbar 32 side is flush with the terminal face 1422b of the external terminal 1422.

[0162] (Effects of the battery 10 and battery pack 1 in Modification 1 of the third embodiment) The effects of the battery 10 and battery pack 1 in Modification 1 of the third embodiment will be described. According to Modification 1 of the third embodiment, the effects of (1), (4), (6), (7), (A), and (B) described in the first embodiment can be obtained.

[0163] (Battery pack 1 of the fourth embodiment) The battery pack 1 of the fourth embodiment has a negative electrode terminal 1520 as shown in Figure 26.

[0164] (Configuration of the negative electrode terminal 1520) The configuration of the negative electrode terminal 1520 will be described with reference to Figure 26. Figure 26 is an enlarged side view showing the cross-section of the negative electrode terminal 1520 of the fourth embodiment and the surrounding components.

[0165] In the fourth embodiment, components identical to those in the third embodiment are given the same reference numerals as in the first embodiment and their descriptions are omitted. In the fourth embodiment, components different from those in the third embodiment are given different reference numerals and described accordingly.

[0166] In the third embodiment, as shown in Figure 25, a fitting recess 1422a4 and a fitting projection 1421a5 were provided on the inner circumferential surface of the insertion hole 1422a of the external terminal 1422 and on the outer circumferential surface of the head 1421a of the connecting terminal 1421, respectively, as fitting portions that fit together with each other.

[0167] In contrast, in the fourth embodiment, as shown in Figure 26, there are no fitting portions that engage with each other on the inner circumferential surface of the insertion hole 1522a of the external terminal 1522 and the outer circumferential surface of the head 1521a of the connecting terminal 1521. The outer circumferential surface of the head 1521a of the connecting terminal 1521 and the inner circumferential surface of the insertion hole 1522a of the external terminal 1522 do not have any interlocking protrusions or recesses that engage with each other from one end to the other of the insertion hole 1522a.

[0168] (Effects of the Battery 10 and Battery Pack 1 of the Fourth Embodiment) The effects of the Battery 10 and Battery Pack 1 of the fourth embodiment will be described. According to this fourth embodiment, the effects (1), (5) to (7), and (A) described in the first embodiment can be obtained.

[0169] Furthermore, in the fourth embodiment, the connection terminal 1521 can be inserted into the insertion hole 1522a of the external terminal 1522 from either one end or the other end of the insertion hole 1522a. This improves the flexibility of the workability when laser joining the connection terminal 1521 and the external terminal 1522. Also, similar to the second embodiment, regardless of the component tolerances of the connection terminal 1521 and the external terminal 1522, the relative height Z position of the connection terminal 1521 and the external terminal 1522 can be adjusted to perform laser joining at a desired position.

[0170] (Battery pack 1 of modification 1 of the fourth embodiment) In the fourth embodiment, as shown in Figure 26, the end face 1521a1 of the negative terminal 1520 on the busbar 32 side was located below the terminal face 1522b of the external terminal 1522. In contrast, in modification 1 of the fourth embodiment, although not shown, the end face 1521a1 of the connecting terminal 1521 on the busbar 32 side is flush with the terminal face 1522b of the external terminal 1522.

[0171] (Effects of the Battery 10 and Battery Pack 1 in Modification 1 of the Fourth Embodiment) The effects of the Battery 10 and Battery Pack 1 in Modification 1 of the Fourth Embodiment will be described. According to Modification 1 of the Fourth Embodiment, the effects of (1), (6), (7), and (A) described in the First Embodiment can be obtained.

[0172] Furthermore, in Modification 1 of the fourth embodiment, similar to the fourth embodiment, the connection terminal 1521 can be inserted into the insertion hole 1522a of the external terminal 1522 from either one end or the other end of the insertion hole 1522a. This improves the degree of freedom in workability when laser joining the connection terminal 1521 and the external terminal 1522. Also, similar to the fourth embodiment, regardless of the component tolerances of the connection terminal 1521 and the external terminal 1522, the relative height Z position of the connection terminal 1521 and the external terminal 1522 can be adjusted to perform laser joining at a desired position.

[0173] (Batteries or battery packs of other embodiments) The batteries or battery packs of the present invention are not limited to the configuration of the battery packs described in the embodiments, but can be configured as appropriate based on the contents described in the claims.

[0174] The embodiments are described in detail or in a simplified manner to clearly illustrate the present invention, and it is not necessary to have all the configurations described, or to have configurations that are not shown. Furthermore, some of the configurations of the embodiments may be deleted, replaced with configurations from other embodiments, or combined with configurations from other embodiments.

[0175] In the embodiment, an example was described in which the negative electrode terminal is an electrode terminal having an external terminal formed by solid-state bonding of a first member mainly composed of copper and a second member mainly composed of aluminum. However, the present invention may also be applied to the positive electrode terminal. In this case, for example, the positive electrode terminal has an external terminal formed by solid-state bonding of a first member mainly composed of aluminum and a second member mainly composed of copper. The negative electrode terminal is formed solely of a material mainly composed of aluminum. The busbar connecting the positive electrode terminal and the negative electrode terminal is formed solely of a material mainly composed of copper. With such a configuration, damage to the laser joint between the external terminal and the connecting terminal in the positive electrode terminal can be suppressed.

[0176] The number of batteries 10 included in the battery pack 1 is not limited to 20. The number of batteries 10 may be, for example, 2 to 19 or 21 or more. The batteries 10 are not limited to lithium-ion batteries. For example, nickel-metal hydride batteries or lead-acid batteries can be used for the batteries 10. The batteries 10 are not limited to secondary batteries. For example, primary batteries can be used for the batteries 10.

[0177] The charge / discharge element of the battery of the present invention is not limited to a wound type charge / discharge element in which a positive electrode, separator, and negative electrode, each formed in a long shape, are bundled and wound together. The charge / discharge element of the battery of the present invention can be a laminated type in which a plurality of rectangular positive electrodes, separators, and negative electrodes are alternately stacked. The charge / discharge element of the battery of the present invention can be a laminated type in which a plurality of relatively short positive electrodes and a plurality of negative electrodes are alternately arranged on a single long separator, facing each other via the separator. In a charge / discharge element with such a configuration, the positive electrode and negative electrode face each other via the separator by folding and stacking the separator. The battery of the present invention is not limited to a configuration with one charge / discharge element. The battery of the present invention can be applied to a configuration with two or more charge / discharge elements. The battery of the present invention is not limited to a configuration in which the charge / discharge element 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 by a laminate film.

[0178] The configuration of the embodiments of the present invention can also be specified as follows.

[0179] As shown in Figures 19 to 24, the battery 10 includes a charge / discharge element 100, an outer casing 400 housing the charge / discharge element 100, electrode terminals (negative electrode terminals) that penetrate the outer casing 400 and are electrically connected to the charge / discharge element 100, and a sealant 600 that insulates and seals the space between the outer casing 400 and the electrode terminals. The electrode terminals (negative electrode terminals) have a connection terminal and an external terminal. The connection terminals include a first metal and are electrically connected to the charge / discharge element 100. The external terminals include a first member including the first metal and a second member including a second metal made of a different material than the first metal. The first member has an inner insertion hole into which the connection terminal is inserted. The first member is laser-bonded to the connection terminal along the edge of the inner insertion hole. The second member is located further away from the charge / discharge element 100 than the first member and has an outer insertion hole into which the connection terminal is inserted. The second member is solid-phase bonded to the first member. The inner edge of the inner insertion hole of the first member and the outer edge of the connection terminal are laser-bonded, thereby forming an annular laser-bonded portion 323 along the edge of the inner insertion hole. The diameter φD of the annular laser-bonded portion 323 is larger than the maximum diameter φd of the portion of the seal 600 that is in contact with the connection terminal. This configuration makes it possible to suppress damage to the laser-bonded portion 323 caused by the compressive reaction force of the seal 600.

[0180] As shown in Figures 25 and 26, the battery 10 includes a charge / discharge element 100, an outer casing 400 housing the charge / discharge element 100, electrode terminals (negative electrode terminals) that penetrate the outer casing 400 and are electrically connected to the charge / discharge element 100, and a sealant 600 that insulates and seals the space between the outer casing 400 and the electrode terminals. The electrode terminals (negative electrode terminals) have a connection terminal and an external terminal. The connection terminals include a first metal and are electrically connected to the charge / discharge element 100. The external terminals include a first member including the first metal and a second member including a second metal made of a different material than the first metal. The first member has an outer insertion hole into which the connection terminal is inserted. The first member is laser-bonded to the connection terminal along the edge of the outer insertion hole. The second member is located closer to the charge / discharge element 100 than the first member and has an inner insertion hole into which the connection terminal is inserted. The second member is solid-phase bonded to the first member. The inner edge of the outer insertion hole of the first member and the outer edge of the connection terminal are laser-bonded, thereby forming an annular laser-bonded portion 1423 along the edge of the outer insertion hole. The diameter φD of the annular laser-bonded portion 1423 is larger than the maximum diameter φd of the portion of the seal 600 that is in contact with the connection terminal. This configuration makes it possible to suppress damage to the laser-bonded portion 1423 caused by the compressive reaction force of the seal 600.

[0181] As shown in Figures 20 to 23 and Figure 25, the connection terminal includes a protrusion (fitting projection) that intersects with the stacking direction of the first and second members and projects toward the second member. The second member of the external terminal is in contact with the first member and includes another protrusion that intersects with the stacking direction and projects toward the connection terminal. The one protrusion (fitting projection) and the other protrusion are in contact with respect to the stacking direction. When laser bonding the connection terminal and the first member, pressing the external terminal toward the connection terminal causes the stepped portion to function as a stopper, thereby suppressing variations in the position of the external terminal in the height direction Z relative to the connection terminal. In other words, the connection terminal and the first and second members can be positioned relative to each other.

[0182] 1. Battery pack, 10. Battery, 10a. Top surface, 10b. Side surface, 10c. Main surface, 20. Holding unit, 21P. First end spacer, 21Q. Second end spacer, 22. Cell spacer, 23P. First end block, 23Pa. Screw hole, 23Pb. Screw hole, 23Pc. Insertion hole, 23Q. Second end block, 23Qb. Screw hole, 23Qc. Insertion hole, 24. Insulating member, 25. Insert nut, 26P. First side plate, 26Pa. Insertion hole, 26Q. Second side plate, 26Qa. Insertion hole, 27. Fastening bolt, 30. Busbar unit, 31. First end busbar, 31a. First joint, 31b. Second joint, 31c. Connecting part, 31d. Insertion hole, 32. Busbar, 32a. First joint, 32b. Second joint, 32c. Connecting part, 33. 33a Second end busbar, 33b First joint, 33b Second joint, 33c Connecting part, 33d Insertion hole, 34 Busbar holder, 34a Opening, 34b Holding part, 34c Insertion part, 40 Voltage detection unit, 41 Voltage detection terminal, 42 Electric wire, 50 Temperature measurement unit, 51 Temperature sensor, 52 Electric wire, 60 Gas discharge unit, 61 Gas duct, 61a Gas transfer part, 61b Gas discharge part, 61c Fixing part, 62 Fastening bolt, 100 Charge / discharge body, 100a One side part, 110 Positive electrode, 111 Positive electrode current collector layer, 111a Current collector part, 111b Positive electrode tab, 111c Side edge, 112 Positive electrode active material layer, 120 Negative electrode, 121 Negative electrode current collector layer, 121a Current collector part, 121b Negative electrode tab, 121c side edge, 122 negative electrode active material layer, 130 separator, 140 electrolyte (electrolyte), 200 current collector, 210 positive electrode current collector plate, 210a base, 210b insertion hole, 220 negative electrode current collector plate, 220a base, 220b insertion hole, 300 electrode terminal, 310 positive electrode terminal, 310a base, 310b insertion part, 310c joint, 320 negative electrode terminal, 320a base, 320b insertion part, 320c joint, 320d recess, 321 connection terminal, 321a head, 321a1 end face, 321a2 large diameter part, 321a3 small diameter part, 321a4 stepped surface, 321a5 321a6 mating projection, 321d inner joint, 322 pressing projection, 322 external terminal, 322a insertion hole, 322a1 large diameter hole, 322a2 small diameter hole, 322a3 stepped surface, 322a4 mating recess, 322a5 outer joint, 322b terminal surface, 322x first member,322y Second member, 322z Joining surface, 323 Laser joint, 400 Outer casing, 410 Container, 410a Opening, 410b Housing section, 420 Lid, 420a Positive side insertion hole (through hole), 420b Negative side insertion hole (through hole), 420c Liquid injection insertion hole, 421 Recess, 422 Pressing protrusion, 430 Dehiscing valve, 440 Sealing plug, 440a Head, 440b Insertion section, 500 Insulator, 510 Insulating cover, 520 Positive side insulating plate, 520a Base, 520b Insertion hole, 520c Protrusion, 530 Negative side insulating plate, 530a Base, 530b Insertion hole, 530b1 Large diameter hole, 530b2 Small diameter hole, 530b3 Stepped surface, 530c protrusion, 530d protrusion, 600 sealing body, 610 positive electrode side first gasket, 610a first insertion part, 610b second insertion part, 610c insertion hole, 620 positive electrode side second gasket, 620a base part, 620b insertion hole, 620c protrusion, 630 negative electrode side first gasket, 630c insertion hole, 631 cylindrical part, 632 flange part (seal part), 632a small diameter part, 632b large diameter part, 640 negative electrode side second gasket, 640a base part, 640b insertion hole, 640b1 large diameter hole, 640b2 small diameter hole, 640c protrusion, 641 recess, 641a bottom surface, 641b inner side surface, 641c outer side surface, 700 Charge / discharge element, 710 positive electrode, 711 positive electrode active material layer, 712 heat-resistant insulating layer, 1120 negative electrode terminal, 1121 connection terminal, 1121a1 end face, 1220 negative electrode terminal, 1221 connection terminal, 1221a head, 1222 external terminal, 1222a insertion hole, 1222x first member, 1222y second member, 1320 negative electrode terminal, 1321 connection terminal, 1321a head, 1321a1 end face, 1322 external terminal, 1322a insertion hole, 1322b terminal surface, 1420 negative electrode terminal, 1421 connection terminal, 1421a head, 1421a1 end face, 1421a4 stepped surface, 1421a5 mating projection, 1422 external terminal, 1422a Insertion hole, 1422a3 Stepped surface, 1422a4 Fitting recess, 1422b Terminal surface, 1422x First member, 1422y Second member, 1423 Laser joint, 1520 Negative terminal, 1521 Connection terminal, 1521a Head, 1521a1 End face, 1521a3 Stepped surface, 1521a4 Fitting recess, 1522 External terminal, 1522a Insertion hole, 1522b Terminal surface,A: Longitudinal direction (of battery 10), B: Shortitudinal direction (of battery 10), X: Stacking direction (of battery pack 1), Y: Width direction (of battery pack 1), Z: Height direction (of battery pack 1), φd: Diameter (of the small diameter portion 632a of the negative electrode side first gasket 630), φD: Diameter (of the annular laser-bonded portions 323, 1423).

Claims

1. A charge / discharge body, an outer casing housing the charge / discharge body, electrode terminals penetrating the outer casing and electrically connected to the charge / discharge body, and a sealing body that insulates and seals the space between the outer casing and the electrode terminals, wherein the electrode terminals include a connection terminal comprising a first metal and electrically connected to the charge / discharge body, and an external terminal having an insertion hole into which the connection terminal is inserted and which contacts the outer edge of the connection terminal, wherein the external terminals include a first member comprising the first metal and laser-bonded to the connection terminal, and a second member comprising a second metal of a different material from the first metal and laminated and solid-phase bonded to the first member, wherein the connection terminals include a head inserted into the insertion hole of the external terminal, and an insertion portion protruding from the head toward the charge / discharge body and penetrating the through hole of the outer casing, and the sealing body includes a sealing portion sandwiched between the head of the connection terminal and the outer casing. A battery wherein a laser-bonded portion is formed along the inner edge of the insertion hole of the external terminal and the outer edge of the head of the connecting terminal, and the diameter of the annular laser-bonded portion is greater than the maximum diameter of the portion in contact with the head in the sealing portion.

2. The battery according to claim 1, wherein, around the insertion hole, the second member is located further away from the charge / discharge element than the first member.

3. The battery according to claim 1, wherein, around the insertion hole, the first member is located further away from the charge / discharge element than the second member.

4. The battery according to claim 1, wherein the external terminal includes a recessed portion facing the connection terminal, the connection terminal includes a protrusion portion projecting toward the external terminal, and the recessed portion and the protrusion portion are in contact in the stacking direction of the first member and the second member.

5. The battery according to claim 1, wherein the end face of the connection terminal opposite to the side on which the charger / discharger is located is located closer to the charger / discharger than the end face of the external terminal opposite to the side on which the charger / discharger is located.

6. The battery according to claim 1, wherein the first metal is a metal mainly composed of copper, and the second metal is a metal mainly composed of aluminum.

7. A battery pack comprising the battery described in claim 1 and a busbar connected to the electrode terminals.

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