Electrode terminal, battery, and battery pack

Abstract

This electrode terminal comprises: a connection terminal (321) having a first member (321x) that contains a first metal and is electrically connected to a charge / discharge body, and a second member (321y) that contains a second metal and is solid-phase bonded to the first member (321x); and an external terminal (322) that contains the second metal and is laser-bonded to the second member (321y). The external terminal (322) includes an insertion hole (322a) into which the second member (321y) is inserted. An annular recess (inner recess (321a2), outer recess (322c)) along the inner edge of the insertion hole (322a) is provided to the end surface of at least one among the external terminal (322) and the second member (321y) of the connection terminal (321). 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 second member (321y) are laser-bonded is positioned at a portion including the side of the recess in a direction along a bonding surface (321z).

Description

Electrode Terminal, Battery, and Battery Pack

[0001] The present invention relates to an electrode terminal, a battery, and a battery pack.

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

[0003] Japanese Patent Application Laid-Open No. 2022-007367

[0004] In a configuration in which 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 an electrode terminal capable of suppressing shrinkage cracking in the laser-bonded portion, a battery having the electrode terminal, and a battery pack having the battery.

[0005] The electrode terminal includes a first member that includes a first metal and is electrically connected to a charge / discharge body of a battery, and a second member that includes a second metal having a material different from that of the first metal and is solid-phase bonded to the first member. The electrode terminal has a connection terminal having a second member and an external terminal that includes the second metal and is located outside the second member in a direction along a bonding surface between the first member and the second member and is laser-bonded to the second member. The external terminal includes an insertion hole into which the second member is inserted and that contacts an outer edge of the second member.An annular recess is provided on an end surface of at least one of the second member of the connection terminal and the external terminal on a side opposite to a side where the charge / discharge body is disposed. An annular laser-bonded portion where an inner edge of the insertion hole of the external terminal and an outer edge of the second member are laser-bonded is located in a portion including a side of the recess in a direction along the bonding surface.

[0006] The battery has the electrode terminal, an electrolytic solution, the charge / discharge body, an exterior body that houses the charge / discharge body and the electrolytic solution, and a sealing body that seals while insulating between the exterior body and the electrode terminal that penetrates the exterior body.

[0007] The battery pack has the battery and a bus bar joined to the electrode terminal.

[0008] According to the present invention, it is possible to obtain an electrode terminal, a battery, and a battery pack capable of suppressing shrinkage cracking in a laser-bonded portion.

[0009] 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 gas duct 61 and 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 the battery 10 partially disassembled. A perspective view showing the charge / discharge body 100 of the 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 the components around the negative electrode terminal 320 of the battery 10 disassembled. A perspective view showing the components around the opening valve 430 and sealing plug 440 of the battery 10 disassembled. A perspective view showing the components around the positive electrode terminal 310 of the battery 10 disassembled. A side view showing a cross-section of the negative electrode terminal 320 and the components around it of the first embodiment. A side view showing an enlarged view of region F20 in Figure 19. A side view showing an enlarged cross-section of the negative electrode terminal 320 and the components around it of the first embodiment, and further showing an enlarged view of region F21 in Figure 20. A side view showing an enlarged view of region F22 in Figure 21. A side view showing an enlarged cross-section of the negative electrode terminal 1120 and its surrounding components in the second embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1220 and its surrounding components in the third embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1320 and its surrounding components in the fourth embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1420 and its surrounding components in the fifth embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1520 and its surrounding components in the sixth embodiment. A side view showing an enlarged cross-section of the negative electrode terminal 1120 and its surrounding components in another embodiment.

[0010] 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.

[0011] (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 21.

[0012] 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 gas duct 61 and 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.

[0013] 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.

[0014] Figure 19 is a cross-sectional side view of the negative electrode terminal 320 and its surrounding components in the first embodiment. Figure 20 is an enlarged side view of region F20 in Figure 19. Figure 21 is an enlarged side view of the cross-section of the negative electrode terminal 320 and its surrounding components in the first embodiment, and is an enlarged side view of region F21 in Figure 20.

[0015] (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.

[0016] 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.

[0017] (Configuration of Battery 10 of Battery Pack 1) The configuration of battery 10 will be explained with reference to Figures 1 to 5 and Figures 7 to 21.

[0018] (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.

[0019] 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.

[0020] 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.

[0021] (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.

[0022] 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).

[0023] 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.

[0024] 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 this configuration, the separator 130 is not essential.

[0025] 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.

[0026] 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.

[0027] (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 21 includes a positive electrode current collector plate 210 and a negative electrode current collector plate 220.

[0028] 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.

[0029] 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.

[0030] (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.

[0031] 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.

[0032] (Configuration of the negative electrode terminal 320 (electrode terminal)) The configuration of the negative electrode terminal 320 will be explained with reference to Figures 8, 9, 16, 19, 20, and 21.

[0033] 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.

[0034] 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 Figures 20 and 21. The connection terminal 321 includes a first member 321x and a second member 321y. The first member 321x is formed of, for example, copper or a copper alloy. The external terminal 322 and the second member 321y are formed of, for example, aluminum or an aluminum alloy.

[0035] At the connection terminal 321, the first member 321x and the second member 321y 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 321x and the second member 321y are heated and joined by pressing them against each other with relatively high pressure. In room temperature pressure welding, the first member 321x and the second member 321y are joined by pressing them against each other with relatively high pressure.

[0036] In the connection terminal 321, the bonding surface 321z between the first member 321x and the second member 321y is a surface perpendicular to the height direction Z of the battery 10. As shown in Figure 19, the bonding surface 321z between the first member 321x and the second member 321y is located between the lid 420 and the busbar 32. That is, as shown in Figure 8, the bonding surface 321z between the first member 321x and the second member 321y is located on the outside of the outer casing 400. In the first embodiment, the negative electrode terminal 320 is positioned relatively above the charge / discharge unit 100. In this state, the bonding surface 321z between the first member 321x and the second member 321y of the negative electrode terminal 320 is located above the upper surface of the electrolyte 140.

[0037] In the negative electrode terminal 320, the insertion portion 320b and the joint portion 320c are formed on the first member 321x. The base portion 320a described above includes a part of the first member 321x, the second member 321y, and the external terminal 322.

[0038] As shown in Figure 8, the external terminal 322 is formed in the shape of a rectangular flat plate. As shown in Figures 20 and 21, the external terminal 322 has an insertion hole 322a that penetrates through the battery 10 in the height direction Z. 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 lid 420 side (lower side in Figure 21). The small-diameter hole 322a2 is located on the busbar 32 side (upper side in Figure 21). 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.

[0039] In the external terminal 322, a terminal surface 322b that contacts the busbar 32 is formed on the end face on the busbar 32 side. An annular outer recess 322c is formed on the end face of the external terminal 322 on the busbar 32 side, along the inner edge of the small diameter hole 322a2. The outer recess 322c is a recess that is recessed downward from the end face (upper end face) of the external terminal 322 on the busbar 32 side, outside the small diameter hole 322a2 of the external terminal 322. 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 21) that is opposite to the side on which the charge / discharge body 100 is located. The annular outer recess 322c, the small diameter hole 322a2, and the large diameter hole 322a1 are arranged concentrically. Of the external terminal 322, the portion between the annular outer recess 322c and the small-diameter hole 322a2 is the portion that is laser-welded (laser-joined) to the connecting terminal 321, and will be hereinafter referred to as the outer joining protrusion 322d.

[0040] 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 420b (through hole) of the cover 420.

[0041] In the connection terminal 321, the head portion 321a is formed in a generally disc shape, as shown in Figures 8 and 16. The head portion 321a is inserted into the insertion hole 322a of the external terminal 322, as shown in Figures 20 and 21. A circular terminal surface 321a1 that contacts the busbar 32 is formed on the end face of the head portion 321a on the busbar 32 side. An annular inner recess 321a2 is formed on the end face of the head portion 321a on the busbar 32 side, along the circular terminal surface 321a1. That is, the inner recess 321a2 is formed along the inner edge of the small diameter hole 322a2. The end face of the head portion 321a on the busbar 32 side corresponds to the end face of the second member 321y of the connection terminal 321 on the busbar 32 side. The end face of the second member 321y of the connection terminal 321 on the busbar 32 side is, as shown in Figure 21, the end face (upper end face and lower end face) of the second member 321y in the height direction Z that is opposite to the side on which the charge / discharge body 100 is located.

[0042] In the connection terminal 321, the inner recessed portion 321a2 is a recessed portion that is recessed downward from the end surface (upper end surface) on the bus bar 32 side of the second member 321y inside the outer edge of the second member 321y of the head portion 321a. The circular terminal surface 321a1, the outer edge of the connection terminal 321, and the annular inner recessed portion 321a2 are arranged concentrically.

[0043] In the connection terminal 321, the head portion 321a includes a large-diameter portion 321a4 inserted into the large-diameter hole 322a1 and a small-diameter portion 321a3 inserted into the small-diameter hole 322a2. The outer diameter of the small-diameter portion 321a3 is smaller than the outer diameter of the large-diameter portion 321a4. A step surface 321a5, which is a surface orthogonal to the height direction Z, is formed between the large-diameter portion 321a4 and the small-diameter portion 321a3.

[0044] In the external terminal 322, the large-diameter portion 321a4 of the connection terminal 321 is in contact with the inner peripheral surface of the large-diameter hole 322a1. The small-diameter portion 321a3 of the connection terminal 321 is in contact with the inner peripheral surface of the small-diameter hole 322a2 of the external terminal 322. The step surface 321a5 of the connection terminal 321 is in contact with the step surface 322a3 of the external terminal 322.

[0045] In the connection terminal 321, the large-diameter portion 321a4 of the head portion 321a includes a fitting convex portion 321a6 that protrudes outward in the radial direction of the connection terminal 321. In other words, the outer peripheral portion of the large-diameter portion 321a4 is formed as the fitting convex portion 321a6. The large-diameter hole 322a1 of the insertion hole 322a of the external terminal 322 includes a fitting concave portion 322a4 that is recessed outward in the radial direction of the insertion hole 322a. The fitting concave portion 322a4 of the external terminal 322 is a concave portion that is recessed facing the outer peripheral surface of the head portion 321a of the connection terminal 321. The fitting convex portion 321a6 of the connection terminal 321 is a convex portion that protrudes toward the external terminal 322. The fitting convex portion 321a6 and the fitting concave portion 322a4 are fitted to each other. The fitting convex portion 321a6 and the fitting concave portion 322a4 are in contact at least in the direction (height direction Z) orthogonal to the joint surface 321z.

[0046] On the inner peripheral surface of the insertion hole 322a of the external terminal 322 and the outer peripheral surface of the head 321a of the connection terminal 321, fitting recesses 322a4 and fitting protrusions 321a6 are provided as fitting portions that fit with and contact each other. By the step surface 322a3 of the fitting recess 322a4 contacting the step surface 321a5 of the fitting protrusion 321a6, the positions of the external terminal 322 and the connection terminal 321 in the height direction Z are defined. The fitting protrusion 321a6 and the fitting recess 322a4 are used for positioning the external terminal 322 and the connection terminal 321 in the height direction Z.

[0047] Among the connection terminals 321, the portion between the annular inner recess 321a2 and the outer peripheral surface of the small-diameter portion 321a3 is the portion to be laser-bonded to the external terminal 322, and hereinafter will be referred to as the inner bonding protrusion 321a7.

[0048] The connection terminal 321 is inserted into the insertion hole 322a of the external terminal 322 from the lower side in FIGS. 20 and 21. By the step surface 321a5 of the fitting protrusion 321a6 contacting the step surface 322a3 of the fitting recess 322a4, the external terminal 322 and the connection terminal 321 are positioned. The inner bonding protrusion 321a7 and the outer bonding protrusion 322d are abutted against each other, and an annular protrusion 320d, which is an annular convex portion, is formed by the inner bonding protrusion 321a7 and the outer bonding protrusion 322d. A laser is irradiated from the upper side in FIGS. 20 and 21 toward the boundary surface between the external terminal 322 and the connection terminal 321 in the annular protrusion 320d, and the external terminal 322 and the connection terminal 321 are laser-bonded. Therefore, 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. The outer bonding protrusion 322d and the inner bonding protrusion 321a7 are integrated by laser bonding and exhibit a convex shape in a cross-sectional view and an annular shape in a plan view.

[0049] In the external terminal 322, the outer connecting projection 322d protrudes from the bottom surface of the outer recess 322c toward the busbar 32. The end face of the outer connecting projection 322d toward the busbar 32 is located closer to the lid 420 than the terminal surface 322b. Therefore, the outer connecting projection 322d does not come into contact with the busbar 32. In the connection terminal 321, the inner connecting projection 321a7 protrudes from the bottom surface of the inner recess 321a2 toward the busbar 32. The end face of the inner connecting projection 321a7 toward the busbar 32 is located closer to the lid 420 than the terminal surface 321a1. Therefore, the inner connecting projection 321a7 does not come into contact with the busbar 32.

[0050] The head portion 321a of the connection terminal 321 and the external terminal 322 have a region (annular protrusion 320d) between the inner recess 321a2 and the outer recess 322c that is recessed in the direction perpendicular to the joining surface 321z (height direction Z) compared to the region inside the inner recess 321a2 of the connection terminal 321 (the region where the terminal surface 321a1 is formed) and the region outside the outer recess 322c of the external terminal 322 (the region where the terminal surface 322b is formed). Therefore, the laser joining portion 323 does not interfere with the busbar 32.

[0051] In the connection terminal 321, the joining surface 321z between the first member 321x and the second member 321y is located at the large-diameter portion 321a4 of the head 321a. In other words, the head 321a includes the second member 321y and the upper part (part) of the first member 321x. Of the connection terminal 321, the member that is laser-bonded to the external terminal 322 is the second member 321y, which contains the same type of metal as the external terminal 322. The second member 321y is inserted into the small-diameter hole 322a2 of the insertion hole 322a of the external terminal 322. The outer joining projection 322d of the external terminal 322 is located outside the roughly disc-shaped second member 321y in the direction along the joining surface 321z. The outer edge of the second member 321y is in contact with the inner edge of the small-diameter hole 322a2 of the external terminal 322.

[0052] The inner edge of the insertion hole 322a of the external terminal 322 and the outer edge of the second member 321y of the connecting terminal 321 are laser-bonded to form an annular laser-bonded portion 323. The laser-bonded portion 323 is formed in the region between the inner recess 321a2 and the outer recess 322c. That is, the laser-bonded portion 323 is located in the portion including the side of the inner recess 321a2 (to the left in Figure 21) in the direction along the bonding surface 321z. Also, the laser-bonded portion 323 is located in the portion including the side of the outer recess 322c (to the right in Figure 21) in the direction along the bonding surface 321z.

[0053] In the connection terminal 321, a disc-shaped pressing projection 321d is formed on the lower surface of the head portion 321a, projecting downward in Figure 21. 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 head portion 321a. The pressing projection 321d presses the negative electrode side first gasket 630 downward in Figure 21.

[0054] As shown in Figure 22, the distance S1 of the gap between the mating recess 322a4 and the mating projection 321a6 in opposing directions is longer than the distance S2 of the gap between the insertion hole of the external terminal 322 and the laser joint portion 323 of the connecting terminal 321 in opposing directions. Distance S1 is, for example, several tens of micrometers to several hundred micrometers. Distance S1 may be, for example, 1 mm. Distance S2 is, for example, several micrometers to less than several tens of micrometers. The gap between the mating recess 322a4 and the mating projection 321a6 in opposing directions is the gap between the outer diameter of the small diameter portion 321a3 and the annular projection 320d. The gap between the mating recess 322a4 and the laser joint portion 323 of the connecting terminal 321 in opposing directions is the gap between the mating recess 322a4 and the mating projection 321a6 at a position different from the outer diameter of the small diameter portion 321a3 and the annular projection 320d.

[0055] As shown in Figure 20, 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 first member 321x of 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.

[0056] (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.

[0057] 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.

[0058] 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.

[0059] As shown in Figures 16 and 20, 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 Figures 20 and 21, the upper end surface of the pressing projection 422 is located outside the upper surface of the lid 420, with which the negative electrode side second gasket 640 abuts.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] (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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] In this configuration, an annular protrusion 530d is formed so as to project radially inward from the inner circumferential surface of the large-diameter hole 530b1. Therefore, in the first embodiment, the creepage distance between the cover 420 and the negative electrode current collector plate 220 is longer compared to the case where the protrusion 530d is not formed. As a result, short circuits between the cover 420 and the negative electrode current collector plate 220 are less likely to occur.

[0069] 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.

[0070] (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.

[0071] 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.

[0072] 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.

[0073] As shown in Figures 20 and 21, the negative electrode side first gasket 630 seals the outer casing 400 by insulating and sealing the space between the lid 420 and the connection terminal 321 that penetrates the lid 420. 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 elastically deforming. The negative electrode side first gasket 630 has a lower elastic modulus and is more easily deformed than the negative electrode side second gasket 640 and the negative electrode side insulating plate 530.

[0074] 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 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.

[0075] 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.

[0076] The small-diameter portion 632a of the flange 632 is pressed downward in Figure 20 by the pressing projection 321d of the aforementioned connecting terminal 321, and is elastically deformed. In Figure 20, 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 in Figure 20 by the pressing projection 422 of the aforementioned lid 420, and is elastically deformed. In Figure 20, 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 figure) by the connecting terminal 321 and the lid 420. Therefore, the flange portion 632 is in close contact with the lower surface of the head portion 321a and the pressing projection 321d of the connecting terminal 321, and the flange portion 632 is in close contact with the bottom surface of the recess 421 and the pressing projection 422 of the lid 420. As a result, the space between the lid 420 and the negative terminal 320 is properly sealed. In this way, the flange portion 632 functions as a sealing portion sandwiched between the head portion 321a of the connecting terminal 321 and the lid 420.

[0077] 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.

[0078] 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.

[0079] 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. 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 the first 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 the first embodiment, the creepage distance between the lid 420 and the base portion 320a of the negative electrode terminal 320 is longer compared to the case where no stepped portion is formed. Therefore, the lid 420 and the negative electrode terminal 320 are less likely to short-circuit. The negative electrode side second gasket 640 is provided with a gap 641 to suppress interference caused by deformation and movement of the connection terminal 321 and the external terminal 322 in the height direction Z. The gap 641 of the negative electrode side second gasket 640 faces the connection terminal 321 and the external terminal 322 along the height direction Z. The portion of the gap 641 of the negative electrode side second gasket 640 facing the large diameter hole 640b1 faces the laser joint 323 where the connection terminal 321 and the external terminal 322 are butt-welded along the height direction Z. The deformation and movement of the connection terminal 321 and the external terminal 322 are caused by laser welding. The deformation includes elastic deformation. The portion of the gap 641 of the negative electrode side second gasket 640 and the cover 420 are either not in contact with each other or are only slightly in contact with each other. The radially outer portion of the gap 641 of the negative electrode side second gasket 640 and the cover 420 are in contact with each other under conditions where pressing force is generated.

[0080] The negative electrode side first gasket 630 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. Therefore, 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.

[0081] The negative electrode side first gasket 630 is elastically deformed by being sandwiched between the negative electrode terminal 320 and the cover 420, thereby maintaining the sealing performance between the negative electrode terminal 320 and the cover 420. As shown in Figure 19, the diameter φD of the annular laser joint portion 323 is larger than the diameter φd of the large diameter portion 632b of the flange portion 632. The 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 φd of the large diameter portion 632b corresponds to the maximum diameter of the portion of the flange portion 632 that is in contact with the head 321a of the connection terminal 321.

[0082] (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.

[0083] 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.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] (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.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] 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.

[0099] (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.

[0100] 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.

[0101] 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.

[0102] (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.

[0103] 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.

[0104] 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.

[0105] (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.

[0106] 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.

[0107] 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.

[0108] (Operation of the negative terminal 320 in the first embodiment) The operation of the negative terminal 320 in the first embodiment will be described.

[0109] Hereinafter, the effects and advantages of the first embodiment will be described in comparison with the configuration in which the inner recess 321a2 and the outer recess 322c are not formed, with the latter being used as a proportional representation. However, in the first embodiment, the negative electrode terminal 320 only needs to have either the inner recess 321a2 or the outer recess 322c.

[0110] In the first embodiment, recesses (outer recess 322c and inner recess 321a2) are formed on the sides of the laser joint 323 (left-right direction in Figure 21). Therefore, the air in the recesses can suppress the movement of heat generated in the laser joint 323 in the left-right direction in Figure 21. The diffusion of heat generated in the laser joint 323 is suppressed, and the laser-irradiated portion can be sufficiently melted with a small amount of heat input. As a result, rapid heating and cooling in the laser joint 323 is suppressed, and the occurrence of shrinkage cracks is suppressed. Furthermore, according to the first embodiment, the amount of energy required for laser irradiation can also be reduced.

[0111] On the other hand, in the proportional configuration, since there is no recess, a metal component is present in the area corresponding to the recesses (inner recess 321a2 and outer recess 322c) in Figures 20 and 21. Heat generated in the laser-irradiated area is more easily transferred through the metal component than through air. Therefore, the heat generated in the laser-irradiated area is easily transferred not only downwards but also to the sides. In other words, in the proportional configuration, heat generated in the laser-irradiated area dissipates easily. To put it another way, in the proportional configuration, heat is less likely to accumulate in the laser-irradiated area. In the proportional configuration, in order to sufficiently melt the laser-irradiated area while allowing the heat from the laser-irradiated area to diffuse, the amount of heat input must be increased compared to the first embodiment. If the amount of heat input to the laser joint is increased, rapid heating and cooling will occur in the laser joint, and there is a risk that shrinkage cracks will occur in the laser joint due to thermal strain.

[0112] 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 portion 320a of the negative electrode terminal 320 from the flange portion 632 of the negative electrode side first gasket 630. Here, if the diameter φD of the laser joint portion 323 is smaller than the diameter φd of the large diameter portion 632b of the flange portion 632, the elastic reaction force of the negative electrode side first gasket 630 will also act on the external terminal 322. Since the connecting 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 portion 323.

[0113] In contrast, in the first embodiment, as described above, the diameter φD of the laser joint 323 is larger than the diameter φd of the large-diameter portion 632b 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 due to the elastic reaction force of the negative electrode side first gasket 630 from occurring in the laser joint 323.

[0114] (Effects of the negative terminal 320, battery 10, and battery pack 1 of the first embodiment) The effects of the negative terminal 320, battery 10, and battery pack 1 of the first embodiment will be described.

[0115] (1) 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 has a first member 321x that is electrically connected to the charge / discharge body 100 of the battery 10, and a second member 321y that is solid-state bonded to the first member. The first member 321x contains a first metal. The second member 321y contains a second metal made of a different material than the first metal. The external terminal 322 contains a second metal. The external terminal 322 is located outside the second member 321y in a direction along the bonding surface 321z between the first member 321x and the second member 321y, and is laser-bonded to the second member 321y. The external terminal 322 includes an insertion hole 322a into which the second member 321y is inserted and which is in contact with the outer edge of the second member 321y. An inner recess 321a2, which is an annular recess along the inner edge of the insertion hole 322a, is provided on the end face of the second member 321y of the connection terminal 321 opposite to the side where the charge / discharge body 100 is located. An outer recess 322c, which is an annular recess along the inner edge of the insertion hole 322a, is provided on the end face of the external terminal 322 opposite to the side where the charge / discharge body 100 is located. An annular laser-bonded portion 323 is formed by laser bonding the inner edge of the insertion hole 322a of the external terminal 322 and the outer edge of the second member 321y. The laser-bonded portion 323 is located in a direction along the bonding surface 321z, including the sides of the inner recess 321a2 and the outer recess 322c. In the first embodiment, the negative electrode terminal 320 only needs to have either the inner recess 321a2 or the outer recess 322c.

[0116] (6) As shown in Figures 7, 20, and 21, the battery 10 includes a negative electrode terminal 320, an electrolyte 140, a charge / discharge element 100, an outer casing 400 housing the charge / discharge element 100 and the electrolyte 140, and a sealing element 600 that insulates and seals the outer casing 400 and the negative electrode terminal 320 that penetrates the outer casing 400. The battery 10 includes the negative electrode terminal 320 described above.

[0117] (10) 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 terminal 320.

[0118] With this configuration, when the connection terminal 321 and the external terminal 322 of the negative electrode terminal 320 are laser-bonded, heat tends to accumulate in the annular protrusion 320d, which is the part that is irradiated with the laser and laser-bonded. In other words, the annular protrusion 320d, which is formed by the connection terminal 321 and the external terminal 322, can suppress relatively rapid heat dissipation after laser irradiation. Therefore, in the process of the annular protrusion 320d going from a melted state to a cooled and solidified state due to laser irradiation, it is difficult for them to separate from each other at the interface between the connection terminal 321 and the external terminal 322 (cracks are less likely to occur). As a result, shrinkage cracks in the laser-bonded portion 323 can be suppressed. Accordingly, with this configuration, shrinkage cracks in the laser-bonded portion of the negative electrode terminal 320 can be suppressed. In other words, a negative electrode terminal 320, a battery 10, and a battery pack 1 can be obtained that can suppress shrinkage cracks in the laser-bonded portion.

[0119] (2) An inner recess 321a2 is formed on the inner side of the outer edge of the second member 321y. An outer recess 322c is formed on the outer side of the insertion hole 322a for the external terminal 322. The laser bonding portion 323 is formed in the region between the inner recess 321a2 and the outer recess 322c.

[0120] In this configuration, the negative electrode terminal 320 has both an inner recess 321a2 and an outer recess 322c. Therefore, it is possible to suppress the relatively rapid heat dissipation in the inner recess 321a2 and the outer recess 322c after laser irradiation. As a result, shrinkage cracks in the laser joint 323 can be sufficiently suppressed.

[0121] (3) The region between the inner recess 321a2 and the outer recess 322c of the second member 321y and the outer terminal 322 is recessed in a direction intersecting (orthogonal to) the joining surface 321z, compared to the region inside the inner recess 321a2 of the second member 321y and the region outside the outer recess 322c of the outer terminal 322.

[0122] With this configuration, interference between the laser joint 323 and the busbar 32 is prevented when welding the busbar 32 to the base 320a of the negative electrode terminal 320. Therefore, the workability and welding accuracy of the busbar 32 to the negative electrode terminal 320 can be improved.

[0123] The upper end surface of the laser-bonded portion 323 may become concave or bulge depending on the laser bonding conditions. If the upper end surface of the laser-bonded portion 323 bulges, post-processing such as cutting may be considered to avoid interference with the busbar 32. However, in this case, there is a risk that damage such as cracks may occur in the laser-bonded portion 323 due to the post-processing. In the first embodiment, the upper end surface of the annular protrusion 320d is located on the lid 420 side (lower side) than the terminal surfaces 321a1 and 322b. Therefore, even if the upper end surface of the laser-bonded portion 323 bulges, interference between the laser-bonded portion 323 and the busbar 32 can be avoided. In other words, in the first embodiment, there is no need to perform post-processing on the laser-bonded portion 323.

[0124] (4) The inner circumferential surface of the insertion hole 322a of the external terminal 322 and the outer circumferential surface of the connecting terminal 321 are provided with a fitting recess 322a4 and a fitting projection 321a6, respectively, which are fitting portions that fit together and are in contact with each other. The distance S1 of the gap between the fitting recess 322a4 and the fitting projection 321a6 in opposing directions is longer than the distance S2 of the gap between the insertion hole of the external terminal 322 and the laser joint portion 323 of the connecting terminal 321 in opposing directions. The gap between the fitting recess 322a4 and the fitting projection 321a6 in opposing directions is the gap between the outer diameter of the small diameter portion 321a3 and the annular projection 320d. The gap along the direction in which the laser joint portion 323 of the external terminal 322 and the connection terminal 321 face each other is the gap between the fitting recess 322a4 and the fitting protrusion 321a6, which is at a different position from the outer diameter of the small diameter portion 321a3 and the annular protrusion 320d.

[0125] With this configuration, when the insertion hole of the external terminal 322 and the laser joint portion 323 of the connecting terminal 321 are facing each other with a distance S2 between them, the fitting recess 322a4 and the fitting projection 321a6 can be faced at a distance S1 that is longer than S2. In other words, with this configuration, interference between the fitting recess 322a4 and the fitting projection 321a6 can be suppressed when the external terminal 322 and the connecting terminal 321 are butt-welded to form the laser joint portion 323.

[0126] (5) The first metal is a metal mainly composed of copper. The second metal is a metal mainly composed of aluminum. The second member 321y that is joined to the busbar 32 at the negative electrode terminal 320 contains the second metal.

[0127] With this configuration, the busbar 32, which is mainly composed of aluminum, and the second member 321y of the negative electrode terminal 320, which is mainly composed of aluminum, are made of similar materials and can therefore be sufficiently laser-bonded.

[0128] (7) When the negative electrode terminal 320 is positioned above the charge / discharge body 100, as shown in Figures 20 and 21, the joint surface 321z between the first member 321x and the second member 321y of the negative electrode terminal 320 is positioned above the upper surface of the electrolyte 140.

[0129] This configuration prevents the electrolyte 140 from coming into contact with the bonding surface 321z. Therefore, corrosion of the bonding surface 321z between the first member 321x and the second member 321y of the negative electrode terminal 320 by the electrolyte 140 can be suppressed.

[0130] (8) The joint surface 321z between the first member 321x and the second member 321y of the negative electrode terminal 320 is located on the outside of the outer casing 400.

[0131] This configuration further suppresses contact between the electrolyte 140 and the bonding surface 321z. Therefore, corrosion of the bonding surface 321z between the first member 321x and the second member 321y of the negative electrode terminal 320 by the electrolyte 140 can be further suppressed.

[0132] (9) The connection terminal 321 includes a head 321a inserted into the insertion hole 322a of the external terminal 322, and an insertion portion 320b protruding from the head 321a toward the charge / discharge body 100. The insertion portion 320b penetrates the negative electrode side insertion hole 420b (through hole) of the outer casing 400. The sealing body 600 includes a negative electrode side first gasket 630. The negative electrode side first gasket 630 includes a flange portion 632 (seal portion) sandwiched between the head 321a of the connection terminal 321 and the outer casing 400. The diameter φD of the annular laser bonding portion 323 is greater than the maximum diameter φd of the portion of the flange portion 632 that is in contact with the head 321a, as shown in Figure 19.

[0133] With this configuration, when assembling the negative electrode terminal 320 to the lid 420 while elastically deforming the negative electrode side first gasket 630, 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 323. Therefore, it is possible to suppress the occurrence of defects such as cracks in the laser joint 323.

[0134] (Second Embodiment) The battery 10 of the second embodiment has electrode terminals 1100 (negative electrode terminal 1120) as shown in Figure 23.

[0135] (Configuration of the negative electrode terminal 1120) The configuration of the negative electrode terminal 1120 will be described with reference to Figure 23. Figure 23 is an enlarged side view showing the cross-section of the negative electrode terminal 1120 of the second embodiment and the surrounding components.

[0136] In the second embodiment, the same components as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their descriptions are omitted.

[0137] In the second embodiment, as shown in Figure 23, the annular projection 1120d is aligned with the terminal surfaces 321a1 and 322b in the height direction Z. On the other hand, in the first embodiment, as shown in Figure 21, the annular projection 320d is recessed toward the charge / discharge body 100 side toward the terminal surface 321a1 in the height direction Z.

[0138] The inner recess 1121a2 has a bottom surface parallel to the joint surface 321z and a pair of sides rising vertically from the bottom surface. The height of the pair of sides (length along the height direction Z in Figure 24) is the same. The outer recess 1122c also has a bottom surface parallel to the joint surface 321z and a pair of sides rising vertically from the bottom surface. The height of the pair of sides is the same. The upper end surface of the annular projection 1120d is flush with the terminal surface 321a1 (upper end surface) of the connection terminal 1121 in the portion inside the inner recess 1121a2. The upper end surface of the annular projection 1120d is flush with the terminal surface 322b (upper end surface) of the outer portion outside the outer recess 1122c of the external terminal 1122.

[0139] (Effects of the negative terminal 1120, battery 10, and battery pack 1 in the second embodiment) The effects of the negative terminal 1120, battery 10, and battery pack 1 in the second embodiment will be explained with reference to Figure 23.

[0140] According to the second embodiment, in addition to the effects (1), (2), and (4) to (10) described in the first embodiment, the following effects can be obtained.

[0141] In the second embodiment, when forming the connection terminal 1121, it is not necessary to cut or machine the annular projection 1120d relative to the terminal surface 321a1. This is because the annular projection 1120d is flush with the terminal surface 321a1. Similarly, in the second embodiment, when forming the external terminal 1122, it is not necessary to cut or machine the annular projection 1120d relative to the terminal surface 322b. This is because the annular projection 1120d is flush with the terminal surface 322b.

[0142] (Third Embodiment) The battery 10 of the third embodiment has electrode terminals 1200 (negative electrode terminal 1220) as shown in Figure 24.

[0143] (Configuration of the negative electrode terminal 1220) The configuration of the negative electrode terminal 1220 will be described with reference to Figure 24. Figure 24 is an enlarged side view showing the cross-section of the negative electrode terminal 1220 of the third embodiment and the surrounding components.

[0144] In the third embodiment, the same components as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their descriptions are omitted.

[0145] In the third embodiment, as shown in Figure 24, there is no fitting portion provided on the inner circumferential surface of the insertion hole 1222a of the external terminal 1222 and the outer circumferential surface of the head 1221a of the connecting terminal 1221 that engages with each other. On the other hand, in the first embodiment, as shown in Figure 21, a fitting recess 322a4 and a fitting projection 321a6 were provided on the inner circumferential surface of the insertion hole 322a of the external terminal 322 and the outer circumferential surface of the head 321a of the connecting terminal 321 that engage with each other.

[0146] (Effects of the negative terminal 1220, battery 10, and battery pack 1 in the third embodiment) The effects of the negative terminal 1220, battery 10, and battery pack 1 in the third embodiment will be explained with reference to Figure 24.

[0147] According to the third embodiment, in addition to the effects (1) to (3) and (5) to (10) described in the first embodiment, the following effects can be obtained.

[0148] In the third embodiment, since the connection terminal 1221 and the external terminal 1222 do not have a mating portion, the connection terminal 1221 and the external terminal 1222 can be easily formed.

[0149] Furthermore, in the third embodiment, the connection terminal 1221 can be inserted into the insertion hole 1222a of the external terminal 1222 from either one end or the other end of the insertion hole 1222a. This improves the flexibility of the work when laser bonding the connection terminal 1221 and the external terminal 1222.

[0150] Furthermore, regardless of the component tolerances of the connection terminal 1221 and the external terminal 1222, the relative height Z position of the connection terminal 1221 and the external terminal 1222 can be adjusted to perform laser bonding at the desired position. For example, even if there is a dimensional difference between the height of the inner bonding protrusion 1221a7 and the height of the outer bonding protrusion 1222d, the height Z positioning of the connection terminal 1221 and the external terminal 1222 can be adjusted so that the upper end surface of the inner bonding protrusion 1221a7 and the upper end surface of the outer bonding protrusion 1222d are flush. Therefore, even if there are component tolerances between the connection terminal 1221 and the external terminal 1222, a good laser-bonded joint 323 can be obtained.

[0151] (Fourth Embodiment) The battery 10 of the fourth embodiment has electrode terminals 1300 (negative electrode terminal 1320) as shown in Figure 25.

[0152] (Configuration of the negative electrode terminal 1320) The configuration of the negative electrode terminal 1320 will be described with reference to Figure 25. Figure 25 is an enlarged side view showing the cross-section of the negative electrode terminal 1320 of the fourth embodiment and the surrounding components.

[0153] In the fourth embodiment, the same components as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their descriptions are omitted.

[0154] In the fourth embodiment, as shown in Figure 25, the inner recess 321a2 is not formed on the connection terminal 1321.

[0155] (Effects of the negative terminal 1320, battery 10, and battery pack 1 in the fourth embodiment) The effects of the negative terminal 1320, battery 10, and battery pack 1 in the fourth embodiment will be explained with reference to Figure 25.

[0156] According to the fourth embodiment, in addition to the effects of (1), (2), and (4) to (10) described in the first embodiment, the following effects can be obtained.

[0157] The laser bonding portion 323 is located laterally to the outer recess 322c (recess) in the direction along the bonding surface 321z, similar to the first embodiment. Therefore, as in the first embodiment, the diffusion of heat in the laser-irradiated portion can be suppressed during laser bonding compared to the case where the outer recess 322c is not provided. As a result, the occurrence of shrinkage cracks in the laser bonding portion 323 is suppressed.

[0158] (Fifth Embodiment) The battery 10 of the fifth embodiment has electrode terminals 1400 (negative electrode terminal 1420) as shown in Figure 26.

[0159] (Configuration of the negative electrode terminal 1420) The configuration of the negative electrode terminal 1420 will be described with reference to Figure 26. Figure 26 is an enlarged side view showing the cross-section of the negative electrode terminal 1420 of the fifth embodiment and the surrounding components.

[0160] In the fifth embodiment, the same components as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their descriptions are omitted.

[0161] In the fifth embodiment, as shown in Figure 26, the external terminal 1422 does not have an external recess 322c.

[0162] (Effects of the negative terminal 1420, battery 10, and battery pack 1 in the fifth embodiment) The effects of the negative terminal 1420, battery 10, and battery pack 1 in the fifth embodiment will be explained with reference to Figure 26.

[0163] According to the fifth embodiment, in addition to the effects of (1), (2), and (4) to (10) described in the first embodiment, the following effects can be obtained.

[0164] The laser bonding portion 323 is located laterally to the inner recess 321a2 (recess) in the direction along the bonding surface 321z, similar to the first embodiment. Therefore, similar to the first embodiment, the diffusion of heat in the laser-irradiated portion can be suppressed during laser bonding compared to the case where the inner recess 321a2 is not provided. As a result, the occurrence of shrinkage cracks in the laser bonding portion 323 is suppressed.

[0165] (Sixth Embodiment) The battery 10 of the sixth embodiment has electrode terminals 1500 (negative electrode terminal 1520) as shown in Figure 27.

[0166] (Configuration of the negative electrode terminal 1520) The configuration of the negative electrode terminal 1520 will be described with reference to Figure 27. Figure 27 is an enlarged side view showing the cross-section of the negative electrode terminal 1520 of the sixth embodiment and the surrounding components.

[0167] In the sixth embodiment, the same components as in the first embodiment are denoted by the same reference numerals as in the first embodiment, and their descriptions are omitted.

[0168] In the sixth embodiment, as shown in Figure 27, the external terminal 1522 is provided with a fitting projection 1522a6, and the connecting terminal 1521 is provided with a fitting recess 1521a4. On the other hand, in the first embodiment, as shown in Figure 21, the external terminal 322 is provided with a fitting recess 322a4, and the connecting terminal 321 is provided with a fitting projection 321a6.

[0169] The inner circumferential surface of the insertion hole 1522a of the external terminal 1522 is provided with a fitting projection 1522a6 that protrudes radially inward from the insertion hole 1522a. The outer circumferential surface of the head 1521a of the connecting terminal 1521 is provided with a fitting recess 1521a4 that is recessed radially inward from the insertion hole 1522a. The fitting projection 1522a6 of the external terminal 1522 is a projection that protrudes toward the outer circumferential surface of the head 1521a of the connecting terminal 1521. The fitting recess 1521a4 of the connecting terminal 1521 is a recess that is recessed opposite to the external terminal 1522. The fitting projection 1522a6 and the fitting recess 1521a4 are fitted together. The fitting projection 1522a6 and the fitting recess 1521a4 are in contact in a direction perpendicular to the joint surface 321z (height direction Z).

[0170] As described above, in this embodiment, a fitting projection 1522a6 and a fitting recess 1521a4 are provided 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, respectively, as fitting portions that fit together and are in contact with each other. The stepped surface 1521a3 of the fitting recess 1521a4 and the stepped surface 1522a5 of the fitting projection 1522a6 are in contact, thereby defining the positions of the external terminal 1522 and the connecting terminal 1521 in the height direction Z. For this reason, the fitting projection 1522a6 and the fitting recess 1521a4 are used for positioning the external terminal 1522 and the connecting terminal 1521 in the height direction Z.

[0171] (Effects of the negative terminal 1520, battery 10, and battery pack 1 in the sixth embodiment) The effects of the negative terminal 1520, battery 10, and battery pack 1 in the sixth embodiment will be explained with reference to Figure 27.

[0172] According to the sixth embodiment, in addition to the effects (1) to (10) described in the first embodiment, the following effects can be obtained.

[0173] As shown in Figure 27, the negative electrode first gasket 630 is not in contact with the external terminal 1522, and the elastic reaction force of the negative electrode first gasket 630 does not directly act on the external terminal 1522. However, due to the tolerances of each component, such as the negative electrode first gasket 630 and the negative electrode terminal 1520, the elastic reaction force of the negative electrode first gasket 630 may act directly on the external terminal 1522.

[0174] Although not shown in the diagram, for example, if the diameter φd of the large-diameter portion 632b of the flange portion 632 of the negative electrode side first gasket 630 is larger than the diameter of the lower opening end of the insertion hole 1522a of the external terminal 1522, the elastic reaction force of the negative electrode side first gasket 630 acts directly on the external terminal 1522. In this case, if the fitting projection 1522a6 is not provided, shear stress is generated in the laser joint portion 323 when the elastic reaction force of the negative electrode side first gasket 630 acts on the external terminal 1522.

[0175] In contrast, in the sixth embodiment, even if the elastic reaction force of the negative electrode first gasket 630 acts on the external terminal 1522, the contact between the fitting projection 1522a6 and the fitting recess 1521a4 can suppress the generation of shear stress in the laser joint 323.

[0176] (Specification of the configuration of the embodiment) The configuration of the embodiment can also be specified as follows:

[0177] As shown in Figures 20 to 24 and Figure 27, the electrode terminal (negative electrode terminal) includes a first member 321x containing a first metal and electrically connected to the battery's charge / discharge element; a second member 321y containing a second metal of a different material than the first metal and solid-state bonded to the first member 321x; and a third member (external terminal) containing the second metal, located outside the second member 321y in a direction along the bonding surface 321z between the first member 321x and the second member 321y, and laser-bonded to the second member 321y. The second member 321y includes an inner base (body of the second member 321y) solid-state bonded to the first member 321x, an outer edge portion that annularly surrounds the outer edge of the inner base in a direction along the bonding surface 321z, and an inner recess that is annularly recessed along the inside of the outer edge portion in the inner base. The third member includes an outer base (body of the external terminal) located outside the second member 321y in a direction along the joining surface 321z, an insertion hole that penetrates the outer base, into which the inner base is inserted and in contact with the outer edge of the inner base, and an outer recess that is annularly recessed along the outside of the insertion hole in the outer base. The inner recess and the outer recess are in the same direction facing the joining surface 321z and are located on the opposite side from the first member 321x. The second member 321y and the third member are laser-joined in the region between the inner recess and the outer recess. With this configuration, shrinkage cracks after welding (after laser joining) of the second member 321y and the third member (external terminal) of the electrode terminal can be suppressed.

[0178] As shown in Figures 20, 21, 24, and 27, it is preferable that the region between the inner recess and the outer recess of the second member 321y and the third member (external terminal) is recessed along the direction intersecting the joint surface 321z (the height direction Z of the battery) compared to the region other than the area between the inner and outer recesses. By recessing the welded portion (laser-jointed portion 323) of the electrode terminal, interference between the welded portion of the electrode terminal and members such as the busbar 32 can be prevented.

[0179] As shown in Figures 20 to 23, 25, and 26, the third member (external terminal) preferably includes a recess (fitting recess) that is recessed facing the second member 321y or the first member 321x, and the second member 321y or the first member 321x preferably includes a protrusion (fitting protrusion) that projects toward the third member. The recess (fitting recess) and the protrusion (fitting protrusion) are in contact. When laser bonding the second member 321y and the third member (external terminal), the stepped portion can be made to function as a stopper by pressing the third member toward the first member 321x, thereby suppressing variations in the position of the first member 321x and the second member 321y in the height direction Z relative to the third member. In other words, the first member 321x and the second member 321y and the third member can be positioned relative to each other.

[0180] As shown in Figures 20 to 27, the electrode terminals may have an annular recess along the inner edge of the insertion hole of the external terminal on the end face opposite to the side where the second member 321y of the connection terminal and at least one of the external terminals are arranged. That is, the annular laser-bonded portion 323 formed by laser bonding the inner edge of the insertion hole of the external terminal and the outer edge of the second member may be located in at least one of the left-right directions shown along the bonding surface 321z. With this configuration, the occurrence of shrinkage cracks in the laser-bonded portion 323 can be suppressed compared to the case where no recess is provided.

[0181] (Electrode terminals, batteries, and battery packs of other embodiments) The electrode terminals, batteries, and battery packs of the present invention are not limited to the configurations of the electrode terminals, batteries, and battery packs described in the embodiments, but can be appropriately configured based on the contents described in the claims.

[0182] The embodiments are described in detail or in a simplified manner to make the present invention easier to understand, 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.

[0183] In the embodiment, an electrode terminal was described in which a first member mainly composed of copper and a second member mainly composed of aluminum are solid-state bonded together. However, the present invention may also be applied to a positive electrode terminal. In this case, for example, the positive electrode terminal is solid-state bonded to a first member mainly composed of aluminum and a second member mainly composed of copper. The negative electrode terminal is formed solely from a material mainly composed of copper. The busbar connecting the positive and negative electrode terminals is formed from a material mainly composed of copper. With this configuration, the occurrence of shrinkage cracks in the laser-bonded portion of the positive electrode terminal can be suppressed.

[0184] In the embodiments shown in Figures 20 to 27, an example was described in which the joining surface 321z is located at the head of the connecting terminal 321. However, the joining surface 321z may also be located at the insertion portion 320b of the connecting terminal 321.

[0185] In the embodiments shown in Figures 20 to 23 and Figures 25 to 27, an example was described in which the bonding surface 321z is located on the charge / discharge body 100 side (lower side in the figure) relative to the stepped surface of the mating portion. However, the bonding surface 321z may also be located on the laser bonding portion 323 side (upper side in the figure) relative to the stepped surface of the mating portion. For example, in the example shown in Figure 21, the bonding surface 321z may be located on the small diameter portion 321a3 of the head 321a of the connection terminal 321. The bonding surface 321z is located below the lower end of the laser bonding portion 323, similar to the embodiments.

[0186] As shown in Figure 28, an annular recess 841 is formed on the upper surface of the base 640a of the negative electrode side second gasket 640. The annular recess 841 includes a bottom surface 841a, an inner side surface 841b, and an outer side surface 841c. The inner side surface 841b and the outer side surface 841c rise vertically from the bottom surface 841a. The inner side surface 841b is located on the central axis side of the connection terminal 321 than the outer circumferential surface of the large diameter portion 321a4 of the connection terminal 321. Along the height direction Z, the inner side surface 841b of the recess 841 is located on the central side (inside) along the longitudinal direction A of the battery 10 than the laser joint 323 to which the connection terminal 321 and the external terminal 322 are butt-welded. Along the height direction, the recess 841 is in the same position as the laser joint 323. The recess 841 cancels out the effects of deformation and movement in the height direction Z caused by the laser joint 323. The outer side surface 841c is located radially outward of the insertion hole 322a than the inner circumferential surface of the large diameter hole 322a1 of the external terminal 322. A space formed by the recess 841 is located directly below the contact surface between the large diameter portion 321a4 and the large diameter hole 322a1. As described above, the negative electrode side second gasket 640 is provided with an annular recess 841. 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 841 is not provided. Consequently, when the negative electrode side second gasket 640 and the negative electrode side first gasket 630 are sandwiched between the base portion 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 portion 320a of the negative electrode terminal 320 is reduced. If a recess with an opening on the radially inward side is provided instead of a recess 841 having an inner side surface 841b, 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 841b. Therefore, even if condensation water enters the recess 841, it is possible to prevent the condensation water from reaching the insertion hole 640b.

[0187] 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.

[0188] 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 facing each other via a separator to a single long separator. In this 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.

[0189] 1 Battery pack, 10 Battery, 20 Holding unit, 21P First end spacer, 21Q Second end spacer, 22 Cell spacer, 23P First end block, 23Q Second end block, 24 Insulating member, 25 Insert nut, 26P First side plate, 26Q Second side plate, 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 Second end busbar, 33a 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, 62 Fastening bolt, 100 Charge / discharge body, 110 Positive electrode, 111 Positive electrode current collector layer, 112 Positive electrode active material layer, 120 Negative electrode, 121 Negative electrode current collector layer, 122 Negative electrode active material layer, 130 Separator, 140 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 terminal, 310a Base, 310b Insertion part, 310c Joint part, 320 Negative terminal, 320a Base, 320b Insertion part, 320c Joint part, 320d Annular protrusion, 321 Connection terminal, 321a Head, 321a1 Terminal surface, 321a2 Inner recess, 321a3 Small diameter part, 321a4 Large diameter part,321a5 Stepped surface, 321a6 Fitting projection, 321a7 Inner joining projection, 321d Pressing projection, 321x First member, 321y Second member, 321z Joining surface, 322 External terminal, 322a Insertion hole, 322a1 Large diameter hole, 322a2 Small diameter hole, 322a3 Stepped surface, 322a4 Fitting recess, 322b Terminal surface, 322c Outer recess, 322d Outer joining projection, 323 Laser joint, 400 Outer casing, 410 Container, 410a Opening, 410b Housing section, 420 Lid, 420a Positive side insertion hole, 420b Negative side insertion hole, 420c Liquid injection insertion hole, 421 Recess, 422 Pressing protrusion, 430 Detachment valve, 440 Sealing plug, 440a Head, 440b Insertion part, 500 Insulator, 510 Insulating cover, 520 Positive electrode side insulating plate, 520a Base, 520b Insertion hole, 520c Protrusion, 530 Negative electrode 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, 620b Insertion hole, 620c Protrusion, 630 First negative electrode gasket, 630c Insertion hole, 631 Cylindrical part, 632 Flange, 632a Small diameter part, 632b Large diameter part, 640 Second negative electrode gasket, 640a Base, 640b Insertion hole, 640b1 Large diameter hole, 640b2 Small diameter hole, 640c Protrusion, 641 Gap, 700 Charge / discharge element, 710 Positive electrode, 711 Positive electrode active material layer, 712 Heat-resistant insulating layer, 841 Recess, 841a Bottom surface, 841b Inner side surface, 841c Outer side surface, 1100 Electrode terminal, 1120 Negative electrode terminal 1120d Annular protrusion,1121 connection terminal, 1121a2 inner recess, 1122 outer terminal, 1122c outer recess, 1200 electrode terminal, 1220 negative electrode terminal, 1221 connection terminal, 1221a head, 1221a7 inner joining protrusion, 1222 outer terminal, 1222a insertion hole, 1222d outer joining protrusion, 1300 electrode terminal, 1320 negative electrode terminal, 1321 connection terminal, 1400 electrode terminal, 1420 negative electrode terminal, 1422 outer terminal, 1500 electrode terminal, 1520 negative electrode terminal, 1521 connection terminal, 1521a head, 1521a3 stepped surface, 1521a4 mating recess, 1522 outer terminal, 1522a Insertion hole, 1522a5 Stepped surface, 1522a6 Fitting projection, φD Diameter of laser joint 323, φd Diameter of large diameter portion 632b of flange 632, S1 Distance of gap between fitting recess 322a4 and fitting projection 321a6 along opposing directions, S2 Distance of gap between insertion hole of external terminal 322 and laser joint 323 of connection terminal 321 along opposing directions, X Stacking direction, Y Width direction, Z Height direction.

Claims

A connection terminal comprising: a first member containing a first metal and electrically connected to the battery's charge / discharge element; and a second member containing a second metal made of a different material from the first metal and solid-state bonded to the first member; An external terminal comprising the second metal, located on the outside of the second member in a direction along the joint surface between the first member and the second member, and laser-bonded to the second member, It has, The external terminal includes an insertion hole into which the second member is inserted and which contacts the outer edge of the second member. An annular recess is provided along the inner edge of the insertion hole on the end face of the second member of the connection terminal and at least one of the external terminals opposite to the side on which the charge / discharge body is located. The annular laser-bonded portion formed by laser bonding the inner edge of the insertion hole of the external terminal and the outer edge of the second member is located in a portion that includes the side of the recess in a direction along the bonding surface. electrode terminal. 　 An inner recess is formed on the inner side of the outer edge of the second member, An outer recess is formed on the outside of the insertion hole of the external terminal, as the recess. The laser bonding portion is formed in the region between the inner recess and the outer recess. The electrode terminal according to claim 1. 　 The second member and the external terminal are such that the region between the inner recess and the outer recess is recessed in a direction intersecting the joining surface, compared to the region inside the inner recess in the second member and the region outside the outer recess in the external terminal. The electrode terminal according to claim 2. 　 The inner circumferential surface of the insertion hole of the external terminal and the outer circumferential surface of the connecting terminal are each provided with a fitting portion that fits into and is in contact with each other. The electrode terminal according to claim 1, wherein the distance of the gap between each of the mating portions is longer than the distance of the gap between the insertion hole of the external terminal and the connecting terminal at a position different from the mating portion. 　 The first metal is a metal whose main component is copper. The second metal is a metal whose main component is aluminum. The electrode terminal according to claim 1. 　 The electrode terminal according to claim 1, Electrolyte and The aforementioned charge / discharge body, An outer casing containing the charge / discharge element and the electrolyte, A sealing body that insulates and seals the space between the outer casing and the electrode terminals that penetrate the outer casing, Having, battery. 　 In a state in which the electrode terminals are positioned relatively above the charge / discharge body, The joint surface between the first member and the second member of the electrode terminal is located above the upper surface of the electrolyte. The battery according to claim 6. 　 The joint surface between the first member and the second member of the electrode terminal is located on the outside of the outer casing. The battery according to claim 7. 　 The aforementioned connection terminal is The head inserted into the insertion hole of the external terminal, An insertion portion that protrudes from the head toward the charge / discharge body and passes through the through hole of the outer casing, Includes, The sealing body includes a sealing portion sandwiched between the head of the connection terminal and the outer casing, The diameter of the annular laser bonding portion is greater than the maximum diameter of the portion in contact with the head in the sealing portion. The battery according to claim 6. 　 The battery according to claim 6, The busbar connected to the electrode terminal, Having, Battery pack.

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