Terminal for power storage device and power storage device

Abstract

To provide a terminal in which a first conductive member and a second conductive member are connected to each other in a reliable connection part, and a power storage device having the terminal.SOLUTION: A negative electrode terminal 40 includes a first conductive member 41 formed of a first metal and a second conductive member 42 formed of a second metal different from the first metal. The second conductive member 42 has a flange part 42f and a shaft part 42s provided in one surface of the flange part 42f. The second conductive member 42 has a first metal joint part 45 metal-joined to the first conductive member 41 in the upper surface of the flange part 42f. The second conductive member 42 has a protrusion 42p in an outer side than the first metal joint part 45. The first conductive member 41 has a first recessed part 41r engaged with the protrusion 42p. The second conductive member 42 has a second metal joint part 46 in which the first conductive member 41 and the second conductive member 42 are metal-joined in the first recessed part 41r and in the protrusion 42p.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a terminal for an electric storage device and an electric storage device. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2022-049726 discloses a terminal including a plate-shaped metal first member and a metal second member ultrasonically welded to one surface of the first member. The first member has a recess formed on the surface opposite to the surface to which the second member is welded. The first member and the second member are ultrasonically welded to each other in the recess. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-049726 Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors wish to further improve the reliability of the connections between the members in a terminal for an electricity storage device in which a plurality of members are connected. [Means for solving the problem]

[0005] The terminal for a power storage device disclosed herein includes a first conductive member made of a first metal and a second conductive member made of a second metal different from the first metal. The second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion. The second conductive member has a first metal joint portion on the upper surface of the flange portion that is metal-jointed to the first conductive member. The second conductive member has at least one of a first recess and a protrusion on the outer periphery side of the first metal joint portion. The first conductive member has the other of the first recess and the protrusion that is fitted into at least one of the first recess and the protrusion. The second conductive member has a second metal joint portion where the first conductive member and the second conductive member are metal-jointed at the first recess and the protrusion.

[0006] In this power storage device terminal, the connection between the first conductive member and the second conductive member is highly reliable. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of the electricity storage device 100. As shown in FIG. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the negative electrode terminal 40 attached to the sealing plate 24. As shown in FIG. [Figure 4] FIG. 4 is a perspective view showing the battery pack 200. As shown in FIG. [Figure 5] FIG. 5 is a schematic diagram of the external conductive member 48. [Figure 6] FIG. 6 is a perspective view of the second conductive member 42. As shown in FIG. [Figure 7] FIG. 7 is a schematic diagram of the protrusion 42p. [Figure 8] FIG. 8 is a schematic diagram of a protrusion 42p according to another embodiment. [Figure 9] FIG. 9 is a cross-sectional view of the negative electrode terminal 40. As shown in FIG. [Figure 10] FIG. 10 is a cross-sectional view of a negative electrode terminal 40A according to another embodiment. [Figure 11] FIG. 11 is a cross-sectional view of a negative electrode terminal 40B according to another embodiment. [Figure 12] FIG. 12 is a cross-sectional view of a negative electrode terminal 40C according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the technology disclosed herein will be described below with reference to the drawings. The embodiments described herein are, of course, not intended to limit the present invention. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, identical reference numerals are used to designate components and parts that perform the same function, and redundant descriptions will be omitted where appropriate. In the following description, the reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the reference numerals X, Y, and Z in the drawings represent the long side direction, short side direction, and height direction of the power storage device, respectively. However, these directions are merely used for convenience of description and do not in any way limit the installation form of the power storage device.

[0009] In this specification, the term "electricity storage device" refers to a general electricity storage device capable of extracting electrical energy. Electricity storage devices include secondary batteries that can be repeatedly charged and discharged by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte, as well as capacitors such as electric double layer capacitors. Hereinafter, an embodiment of a method for manufacturing an electricity storage device will be described in which a lithium ion secondary battery is used.

[0010] <Electricity storage device 100> FIG. 1 is a perspective view of an energy storage device 100. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. In FIG. 2, the gasket 50 and the insulator 60 are omitted. FIG. 3 is a cross-sectional view showing a negative electrode terminal 40 attached to a sealing plate 24. FIG. 4 is a perspective view showing a battery pack 200. FIG. 4 illustrates a configuration in which a plurality of energy storage devices 100 disclosed herein are connected in series via bus bars 90, each serving as a single cell.

[0011] As shown in FIG. 2 , the energy storage device 100 includes an electrode assembly 10, a case 20, a positive electrode terminal 30, and a negative electrode terminal 40. The energy storage device 100 may include an external conductive member 48. The energy storage device 100 is characterized by including the positive electrode terminal 30 and / or the negative electrode terminal 40 disclosed herein, and other configurations may be similar to conventional devices. The energy storage device 100 is preferably a secondary battery, more preferably a non-aqueous electrolyte secondary battery. The energy storage device 100 is preferably a prismatic secondary battery. Here, the energy storage device 100 is a lithium ion secondary battery. Although not shown, the energy storage device 100 further includes an electrolyte. The energy storage device 100 is configured by housing the electrode assembly 10 and an electrolyte (not shown) in a case 20.

[0012] The electrode assembly 10 may be the same as a conventional one and is not particularly limited. The electrode assembly 10 includes a positive electrode and a negative electrode (not shown). The electrode assembly 10 is, for example, a flat wound electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state via a strip-shaped separator and wound around a winding axis. However, in other embodiments, the electrode assembly 10 may be a laminated electrode assembly in which a square-shaped (typically rectangular) positive electrode and a square-shaped (typically rectangular) negative electrode are stacked in an insulated state.

[0013] The positive electrode has a positive electrode current collector 11 and a positive electrode mixture layer (not shown) fixed on the positive electrode current collector 11. The positive electrode current collector 11 is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode mixture layer contains a positive electrode active material (e.g., a lithium transition metal composite oxide). The negative electrode has a negative electrode current collector 12 and a negative electrode mixture layer (not shown) fixed on the negative electrode current collector 12. The negative electrode current collector is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The negative electrode mixture layer contains a negative electrode active material (e.g., a carbon material such as graphite).

[0014] As shown by the diagonal lines in FIG. 2 , a laminated portion is formed in the center of the electrode body 10 in the long side direction X, where a positive electrode mixture layer and a negative electrode mixture layer are laminated in an insulated state. Meanwhile, at the left end of the electrode body 10 in the long side direction X, a portion of the positive electrode current collector 11 where no positive electrode mixture layer is formed (exposed positive electrode current collector portion) protrudes from the laminated portion. A positive electrode current collector member 13 is attached to the exposed positive electrode current collector portion. The positive electrode current collector member 13 may be made of the same metal material as the positive electrode current collector 11, such as a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode current collector member 13 is disposed within the case 20. The positive electrode current collector member 13 electrically connects the positive electrode to the positive electrode terminal 30.

[0015] Furthermore, at the right end of the electrode assembly 10 in the long side direction X, a portion of the negative electrode current collector 12 on which the negative electrode mixture layer is not formed (negative electrode current collector exposed portion) protrudes from the laminated portion. A negative electrode current collector 14 is attached to the negative electrode current collector exposed portion. The material (metal type) of the negative electrode current collector 14 may be different from that of the positive electrode current collector 13. The negative electrode current collector 14 may be made of the same metal type as the negative electrode current collector 12, for example, a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The negative electrode current collector 14 is disposed within the case 20. The negative electrode current collector 14 electrically connects the negative electrode and the negative electrode terminal 40. The negative electrode current collector 14 electrically connects the negative electrode and the negative electrode terminal 40 inside the case 20.

[0016] The electrolyte may be the same as conventional ones and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (nonaqueous electrolytic solution) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may be a solid (solid electrolyte) and integrated with the electrode assembly 10.

[0017] The case 20 is a housing that houses the electrode assembly 10. Here, the case 20 is formed in a flat, bottomed rectangular parallelepiped (rectangular) shape. However, the shape of the case 20 is not limited to a rectangular shape and may be any shape, such as a cylindrical shape. The material of the case 20 is not particularly limited and may be the same as that conventionally used. The case 20 is made of a lightweight metal material with good thermal conductivity, such as aluminum, an aluminum alloy, or stainless steel. The case 20 includes an exterior body 22 having an opening 22h and a sealing plate 24 that closes the opening 22h. The case 20 preferably includes the exterior body 22 and the sealing plate 24. The case 20 is integrated by joining (e.g., welding) the sealing plate 24 to the periphery of the opening 22h of the exterior body 22. The case 20 is hermetically sealed (sealed).

[0018] Exterior body 22 has a bottom surface 22d. Sealing plate 24 faces bottom surface 22d of exterior body 22. Sealing plate 24 is attached to exterior body 22 so as to close opening 22h of exterior body 22. Here, sealing plate 24 has a substantially rectangular shape. Note that in this specification, the term "substantially rectangular shape" encompasses not only a perfect rectangular shape (rectangular shape), but also shapes in which, for example, corners connecting the long and short sides of a rectangle are rounded, or shapes in which the corners have cutouts.

[0019] The positive electrode terminal 30 and the negative electrode terminal 40 protrude to the outside of the case 20. Here, the positive electrode terminal 30 and the negative electrode terminal 40 each protrude from the same surface of the case 20 (specifically, the sealing plate 24). However, the positive electrode terminal 30 and the negative electrode terminal 40 may each protrude from different surfaces of the case 20. The positive electrode terminal 30 and the negative electrode terminal 40 are respectively disposed at both end portions of the sealing plate 24 in the long side direction X. The positive electrode terminal 30 and / or the negative electrode terminal 40 are an example of a "terminal for a power storage device."

[0020] As shown in FIG. 2, the positive electrode terminal 30 is electrically connected to the positive electrode of the electrode assembly 10 via a positive electrode current collector 13 inside the case 20. The negative electrode terminal 40 is electrically connected to the negative electrode of the electrode assembly 10 via a negative electrode current collector 14 inside the case 20. The positive electrode terminal 30 and the negative electrode terminal 40 are each attached to the case 20 (specifically, the sealing plate 24). The positive electrode terminal 30 and the negative electrode terminal 40 are preferably fixed to the case 20 (specifically, the sealing plate 24). The positive electrode terminal 30 and the negative electrode terminal 40 are each insulated from the sealing plate 24 via a gasket 50 (see FIG. 3) and an insulator 60 (see FIG. 3).

[0021] The configurations of the positive electrode terminal 30 and the negative electrode terminal 40 of the energy storage device 100 will be described in detail below, taking the terminal structure on the negative electrode terminal 40 side as an example. The terminal structure described below is preferably provided on the negative electrode terminal 40 side. Note that the terminal structure described below may be provided on the positive electrode terminal 30 side, or may be provided on both the positive electrode terminal 30 side and the negative electrode terminal 40 side. In that case, in the following description, "negative electrode" can be read as "positive electrode" as appropriate.

[0022] As shown in FIG. 3, the sealing plate 24 is formed with a terminal mounting hole 24h penetrating in the up-down direction Z. The terminal mounting hole 24h is provided in the case 20 (in this embodiment, the sealing plate 24). It is preferable that the negative electrode terminal 40 is inserted into the terminal mounting hole 24h. Although not shown, the terminal mounting hole 24h here has a circular shape (for example, a perfect circle) in a plan view. The terminal mounting hole 24h has an inner diameter large enough to allow a crimped portion 40c of the negative electrode terminal 40, described later, to be inserted therethrough before crimping. The terminal mounting hole 24h is formed smaller than a flange portion 42f of the negative electrode terminal 40, described later.

[0023] The negative current collector 14 is attached to the exposed portion of the negative current collector 12 and forms a conductive path electrically connecting the negative electrode and the negative terminal 40. The negative current collector 14 has a flat portion 14f that extends horizontally along the inner surface of the sealing plate 24. The flat portion 14f has an opening 14h at a position corresponding to the terminal mounting hole 24h. The opening 14h has an inner diameter large enough to allow the crimped portion 40c of the negative terminal 40 (described later) to be inserted therethrough before crimping. The negative current collector 14 is fixed to the sealing plate 24 together with the negative terminal 40 by crimping. A resin insulating member is preferably disposed between the case 20 (in this embodiment, the sealing plate 24) and the negative current collector 14. In this embodiment, the negative current collector 14 is fixed to the sealing plate 24 together with the negative terminal 40 in a state of being insulated via an insulator 60.

[0024] The gasket 50 is an insulating member disposed between the upper surface (outer surface) of the sealing plate 24 and the negative electrode terminal 40. An insulating member (e.g., the gasket 50) is preferably disposed between the case 20 (e.g., the sealing plate 24) and the negative electrode terminal 40. Here, the gasket 50 serves to insulate the sealing plate 24 from the negative electrode terminal 40 and also to close the terminal mounting hole 24h. The gasket 50 is made of an electrically insulating and elastically deformable resin material, for example, a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA), polyphenylene sulfide resin (PPS), aliphatic polyamide, or the like.

[0025] The gasket 50 has a tubular portion 51 and a base portion 52. The tubular portion 51 is a portion that prevents direct contact between the sealing plate 24 and the crimped portion 40c of the negative electrode terminal 40. The tubular portion 51 has a hollow cylindrical shape. The tubular portion 51 has a hole portion 51h that penetrates in the vertical direction Z. The hole portion 51h is formed so that the crimped portion 40c of the negative electrode terminal 40 can be inserted therethrough before crimping. The tubular portion 51 is inserted into the terminal mounting hole 24h of the sealing plate 24. The base portion 52 is a portion that prevents direct contact between the sealing plate 24 and a flange portion 42f of the negative electrode terminal 40, which will be described later. The base portion 52 is connected to the upper end of the tubular portion 51. The base portion 52 extends horizontally from the upper end of the tubular portion 51. The base 52 is formed, for example, in a circular ring shape so as to surround the terminal mounting hole 24h of the sealing plate 24. The base 52 extends along the upper surface of the sealing plate 24. The base 52 is sandwiched between the lower surface 42d of the flange portion 42f of the negative electrode terminal 40 and the upper surface of the sealing plate 24, and is compressed in the vertical direction Z by crimping.

[0026] The insulator 60 is an insulating member disposed between the lower surface (inner surface) of the sealing plate 24 and the negative electrode current collecting member 14. An insulating member (e.g., the insulator 60) is preferably disposed between the case 20 (e.g., the sealing plate 24) and the negative electrode current collecting member 14. The insulator 60 has a flat plate-shaped portion that extends horizontally along the inner surface of the sealing plate 24. A hole 60h is formed in this flat plate-shaped portion at a position corresponding to the terminal mounting hole 24h. The hole 60h has an inner diameter large enough to allow the shaft portion 42s of the negative electrode terminal 40 to be inserted therethrough. The insulator 60 is made of an elastically deformable resin material that is resistant to the electrolyte used, has electrical insulating properties, and is, for example, a fluorinated resin such as perfluoroalkoxy fluororesin (PFA) or polyphenylene sulfide resin (PPS). The flat plate portion of the insulator 60 is sandwiched between the lower surface of the sealing plate 24 and the upper surface of the negative electrode current collecting member 14, and is compressed in the vertical direction Z by caulking.

[0027] <Negative terminal 40> The negative electrode terminal 40 includes a first conductive member 41 and a second conductive member 42. As shown in FIG. 3 , the negative electrode terminal 40 extends from the inside to the outside of the case 20 through the terminal mounting hole 24h. The negative electrode terminal 40 may further include an external conductive member 48 connected to the first conductive member 41 outside the case 20.

[0028] The negative electrode terminal 40 includes two types of conductive members, that is, a first conductive member 41 and a second conductive member 42, which are electrically connected to each other via first metal joints 45 and .

[0029] The negative electrode terminal 40 is inserted into the terminal mounting hole 24h of the sealing plate 24 and the opening 14h of the negative electrode current collector 14, and its leading end in the insertion direction is crimped onto the negative electrode current collector 14. Specifically, the crimped portion is crimped to the peripheral portion surrounding the opening 14h of the negative electrode current collector 14. A crimped portion 40c is formed at the lower end of the negative electrode terminal 40. The negative electrode terminal 40 is fixed to the sealing plate 24 and electrically connected to the negative electrode current collector 14 by crimping. In this example, the crimped portion 40c is cylindrical. However, the shape of the crimped portion 40c is not limited to a cylindrical shape and may be any shape, such as a columnar shape. It is preferable that the crimped portion 40c be welded to the negative electrode current collector 14. The first conductive member 41 and the second conductive member 42 constituting the negative electrode terminal 40 will be described below.

[0030] <First conductive member 41> The first conductive member 41 is a member disposed outside the case 20. The first conductive member 41 is made of a first metal. The first metal is a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The first metal side is preferably aluminum or an aluminum alloy. Here, the first conductive member 41 is made of aluminum. The first conductive member 41 is preferably made of a metal that has a lower Vickers hardness (is softer) than the second conductive member 42. The first conductive member 41 may be made of the same metal as the positive electrode current collecting member 13, or an alloy that has the same metal element as the first component (the component with the highest mass ratio; the same applies below).

[0031] The first conductive member 41 preferably has a diameter greater than its thickness. In this embodiment, the first conductive member 41 is plate-shaped (more specifically, flat plate-shaped). The first conductive member 41 is preferably substantially disk-shaped in plan view. The first conductive member 41 has a first surface 41a and a second surface 41b. The first surface 41a is a surface that is joined to the second conductive member 42.

[0032] The second surface 41b is the surface opposite to the first surface 41a. In this embodiment, an annular rib 41ri is formed on the second surface 41b of the first conductive member 41. The rib 41ri can be formed continuously in an annular shape. An external conductive member 48 is welded to the second surface 41b via the rib 41ri. The external conductive member 48 preferably extends along the longitudinal direction of the sealing plate 24. The external conductive member 48 is preferably made of the same type of metal as the first conductive member 41 (in this embodiment, aluminum or an aluminum alloy).

[0033] As shown in FIG. 4, when the battery pack 200 is fabricated, a bus bar 90 is connected to the external conductive member 48, which is connected to the first conductive member 41. FIG. 5 is a schematic diagram of the external conductive member 48. FIG. 5 schematically illustrates the external conductive member 48 and the bus bar 90 as viewed from above. In FIG. 5, the second conductive member 42, which is hidden by the external conductive member 48, is indicated by a dashed line. As shown in FIG. 5, the bus bar 90 is connected to the external conductive member 48 at a bus bar weld 48a. The bus bar 90 and the external conductive member 48 can be welded by, for example, laser welding. Note that the external conductive member 48 does not necessarily have to be attached to the second surface 41b of the first conductive member 41. When the battery pack 200 (see FIG. 4) is fabricated, the bus bar 90 may be directly connected to the first conductive member 41 without the external conductive member 48.

[0034] <Second conductive member 42> As shown in FIG. 3, the second conductive member 42 is a member that extends from the inside to the outside of the case 20 through the terminal mounting hole 24h. The second conductive member 42 is made of a second metal different from the first metal. The second metal is, for example, a conductive metal such as copper, a copper alloy, nickel, stainless steel, iron, or an iron alloy. The second metal is preferably made of copper or a copper alloy. In this example, the second conductive member 42 is made of copper. The second conductive member 42 is preferably made of a metal that has a higher Vickers hardness (is harder) than the first conductive member 41. The second metal may be the same metal as the negative electrode current collecting member 14 or an alloy containing the same metal element as the first component. Part or all of the surface of the second conductive member 42 may be coated with another metal by Ni plating, tin plating, or the like.

[0035] The second conductive member 42 has a flange portion 42f and a shaft portion (connection portion) 42s. The shaft portion 42s is connected to the negative current collecting member 14 and serves as the crimped portion 40c. The shaft portion 42s is provided on one surface (the lower surface 42d in this embodiment) of the flange portion 42f. The shaft portion 42s is inserted into the terminal mounting hole 24h of the case 20 (the sealing plate 24 in this embodiment) and the opening 14h of the negative current collecting member 14. A base portion 52 of a gasket 50 is disposed between the flange portion 42f and the sealing plate 24. A cylindrical portion 51 of the gasket 50 is disposed between the shaft portion 42s and the sealing plate 24. The diameter of the shaft portion 42s increases toward the tip. The increased diameter portion is connected to the negative current collecting member 14. The expanded diameter portion is also referred to as a crimped portion 40c, and is preferably inserted into the opening 14h of the negative current collector 14 and crimped to connect to the negative current collector 14. From the viewpoint of improving electrical conductivity, the crimped portion 40c and a part of the negative current collector 14 are preferably joined by laser welding or the like.

[0036] The flange portion 42f is a portion having a larger diameter than the shaft portion 42s in the planar directions (X direction and Y direction). In other words, the flange portion 42f is a portion at one end of the shaft portion 42s that has a larger diameter than the shaft portion 42s. The flange portion 42f is a portion that is disposed outside the case 20. The flange portion 42f is connected to the first conductive member 41.

[0037] The shape of the flange portion 42f is not particularly limited. The flange portion 42f may be, for example, substantially circular or substantially polygonal in plan view along the direction in which the shaft portion 42s extends (height direction). The flange portion 42f is preferably substantially circular in plan view. The substantially circular shape is not limited to a perfect circle, and includes shapes in which a notch is formed in part of the outer circumferential surface. It is preferable that at least a part of the outer circumferential edge of the flange portion 42f is circular. For example, it is preferable that the shape of the outer circumferential edge going around the entire circumference at the same height in the thickness direction of the flange portion 42f is circular.

[0038] The flange portion 42f has a large diameter portion 42fa and a small diameter portion 42fb. The large diameter portion 42fa has an outer diameter larger than that of the small diameter portion 42fb. The large diameter portion 42fa is a substantially disk-shaped portion having substantially the same diameter in the thickness direction (height direction). In other words, the outer peripheral edge of the upper surface 42u of the large diameter portion 42fa is circular. A small diameter portion 42fb protruding upward is formed in the approximate center of the upper surface 42u of the large diameter portion 42fa. The small diameter portion 42fb has a shape that conforms to the second recess 41R. The diameter of the small diameter portion 42fb increases toward the tip side (the side farther from the flange portion 42f). The diameter of the small diameter portion 42fb decreases from the tip to the base end. The diameter of the small diameter portion 42fb may be smaller than the diameter of the shaft portion 42s.

[0039] The outer diameters of the large diameter portion 42fa and the small diameter portion 42fb refer to the outer shapes of the portions of each portion that have the largest diameter from the central axis CL. In this embodiment, the outer diameter of the small diameter portion 42fb refers to the outer diameter of the upper surface 42u1 on the tip side of the small diameter portion 42fb. In this embodiment, the outer diameter of the large diameter portion 42fa is approximately constant in the axial direction, and therefore refers to the outer diameter at any position in the axial direction.

[0040] The negative electrode terminal 40 has a contact portion C where the first conductive member 41 and the second conductive member 42 contact each other. In this embodiment, a portion of the flange portion 42f of the second conductive member 42 contacts the first conductive member 41 at the first recess 41r. At the contact portion C, the second conductive member 42 has a first metal joint portion 45 and a second metal joint portion 46. The first metal joint portion 45 and the second metal joint portion 46 are joints where the first conductive member 41 and the second conductive member 42 are joined by metal bonding. The first metal joint portion 45 is formed closer to the center than the second metal joint portion 46 on the upper surface of the flange portion 42f. This can reduce deterioration of the first metal joint portion 45 due to loads applied via the electrolyte or external connecting members.

[0041] In this embodiment, the first metal joint 45 is formed on the upper surface 42u1 of the small diameter portion 42fb. From the viewpoint of suppressing corrosion due to an electrolyte, water, or the like, the first metal joint 45 is preferably formed by metal-bonding the upper surface of the flange portion 42f and the bottom surface of the recess of the first conductive member 41 (in this embodiment, a first bottom surface 41R1 of a second recess 41R (see FIG. 9) described later). It is more preferable that the first metal joint 45 be formed in a central portion of the upper surface of the flange portion 42f.

[0042] Here, metal bonding refers to joining multiple metal members together by metallurgical bonding, and does not include joining by mechanical fastening. Metal joints 45, 46 are preferably formed by ultrasonic bonding, diffusion bonding, laser welding, or the like. From the viewpoint of preventing the formation of brittle intermetallic compounds at the bonding interface, metal joints 45, 46 are preferably ultrasonic joints formed by ultrasonic bonding. In this embodiment, metal joints 45, 46 are ultrasonic joints formed by ultrasonic bonding of first conductive member 41 and second conductive member 42.

[0043] The second conductive member 42 has a protrusion 42p on the outer circumferential side of the first metal joint portion 45. The protrusion 42p is provided at a contact portion C between the first conductive member 41 and the second conductive member 42. In this embodiment, the protrusion 42p is formed on an upper surface 42u of the large diameter portion 42fa, which is part of the upper surface of the flange portion 42f.

[0044] FIG. 6 is a perspective view of the second conductive member 42. FIG. 7 is a schematic diagram of a protrusion 42p. FIG. 8 is a schematic diagram of a protrusion 42p according to another embodiment. As shown in FIG. 6, the protrusion 42p is provided on the upper surface 42u of the large diameter portion 42fa near the small diameter portion 42fb. The protrusion 42p may be connected to the small diameter portion 42fb or may be separated from the small diameter portion 42fb. In this embodiment, the protrusion 42p is connected to the small diameter portion 42fb and is provided to extend radially from the base end of the small diameter portion 42fb.

[0045] As shown in FIG. 7, the protrusion 42p has a flat tip. The cross section of the protrusion 42p along the length direction (radial direction of the flange portion 42f) is generally trapezoidal. The shape of the protrusion 42p is not limited to this, and as shown in FIG. 8, the protrusion 42p may have a pointed tip. The cross section of the protrusion 42p along the length direction may be generally triangular. The dimensions and shape of the protrusion 42p are not particularly limited. From the viewpoint of durability of the protrusion 42p, it is preferable that the aspect ratio A / B, which is expressed as the width A of the base end of the protrusion 42p to the height B of the protrusion 42p, be 1 or greater.

[0046] As shown in Figures 6 and 7, the protrusions 42p are formed along the radial direction of the flange portion 42f. The length of the protrusions 42p in the radial direction is not particularly limited. For example, the length of the protrusions 42p in the radial direction is preferably 0.25 mm or more, and more preferably 0.5 mm or more. Furthermore, the length of the protrusions 42p in the radial direction is preferably 5 mm or less, and more preferably 3 mm or less.

[0047] As shown in FIG. 5, six protrusions 42p are provided on the upper surface 42u of the large diameter portion 42fa of the flange portion 42f. The six protrusions 42p are provided at approximately the same distance from the center in the radial direction. The protrusions 42p may be provided, for example, at approximately equal intervals in the circumferential direction. The number, arrangement, intervals, etc. of the protrusions 42p are not particularly limited. The number of protrusions 42p may be one. From the viewpoint of improving the conductivity between the first conductive member 41 and the second conductive member 42, the number of protrusions 42p is preferably more than one, and more preferably four or more. From the viewpoint of productivity, the number of protrusions 42p may be, for example, 20 or less, 12 or less, or 8 or less.

[0048] FIG. 9 is a cross-sectional view of the negative electrode terminal 40. FIG. 9 shows a cross section near the interface between the first conductive member 41 and the second conductive member 42. The sealing plate 24, the gasket 50, the insulator 60, the negative electrode current collecting member 14, and other components are omitted from FIG. 9. As shown in FIG. 9, the protrusions 42p of the second conductive member 42 are wedged into the first conductive member 41. In other words, the first conductive member 41 has first recesses 41r that fit with the protrusions 42p of the second conductive member 42. The first conductive member 41 has the same number of first recesses 41r as the protrusions 42p of the second conductive member 42. The first recesses 41r are formed at the same positions as the protrusions 42p and in shapes corresponding to the protrusions 42p. It is preferable that a plurality of first recesses 41r and a plurality of protrusions 42p are provided. The second metal joint 46 described above is formed by metal-joining the first conductive member 41 and the second conductive member 42 at the first recess (in this embodiment, the first recess 41r of the first conductive member 41) and the protrusion (in this embodiment, the protrusion 42p of the second conductive member 42). Therefore, the first metal joint 45 formed on the upper surface 42u1 of the small diameter portion 42fb and the second metal joint 46 formed on the upper surface 42u of the large diameter portion 42fa are formed at different positions in the extension direction of the shaft portion 42s.

[0049] The second metal joint 46 is not particularly limited as long as it is formed on the outer periphery of the first metal joint 45. In this embodiment, the first metal joint 45 is formed on the central axis CL of the negative electrode terminal 40 (shank 42s). The second metal joint 46 is formed at a position away from the central axis CL. However, this is not limited to this form. The first metal joint 45 and the second metal joint 46 may be connected. The first metal joint 45 and the second metal joint 46 may be formed on the same plane. A region that is not joined by metal bonding may be provided between the first metal joint 45 and the second metal joint 46.

[0050] However, when an energy storage device moves or vibrates during use, a load may be applied to a terminal connected to an external connection member, such as a bus bar. When a terminal is formed by metal-joining multiple conductive members, the load applied to the terminal via the external connection member may also act on the joint interface between the multiple conductive members. For example, when a bus bar moves in a circumferential direction relative to the central axis of the terminal, a force may be applied to the conductive member connected to the bus bar in a direction rotating around the central axis. This may also apply a load to the metal joint. The inventors have found that when a load is applied to a metal joint, there is a concern that the joint interface of the metal joint may peel off or the joint area at the joint interface may decrease. In such a case, there is a concern that the conductivity between the multiple conductive members constituting the terminal may decrease.

[0051] In the above-described embodiment, the second conductive member 42 has a first metal joint 45, which is metal-jointed to the first conductive member 41, on the upper surface of the flange portion 42f. This ensures good conductivity between the first conductive member 41 and the second conductive member 42. The second conductive member 42 has a protrusion 42p that fits into the first recess 41r of the first conductive member 41 on the outer circumferential side of the first metal joint 45. With this configuration, even if an external connection member such as a bus bar 90 applies a force in the circumferential direction about the central axis CL of the negative electrode terminal 40, the engagement between the protrusion 42p and the first recess 41r makes it difficult for a load to be applied in a direction that rotates the first conductive member 41 relative to the second conductive member 42. This makes it easy to maintain the first metal joint 45, thereby ensuring good reliability of conductivity between the first conductive member 41 and the second conductive member 42 in the negative electrode terminal 40. Furthermore, a second metal joint 46 is formed between the first recess 41r and the protrusion 42p. This improves the electrical continuity between the first conductive member 41 and the second conductive member 42. The effect of reducing the load on the first metal joint 45 is exerted both when an external connecting member is connected directly to the first conductive member 41 of the negative electrode terminal 40 and when an external connecting member is connected via the external conductive member 48.

[0052] The greater the distance between the central axis CL of the negative electrode terminal 40 and the connection portion of the external connection member, the greater the load applied to the terminal via the external connection member. Therefore, when the external conductive member 48 is connected to the negative electrode terminal 40 and the external conductive member 48 is connected to an external connection member, the effect of reducing the load applied to the first metal joint portion 45 can be greater.

[0053] In the above-described embodiment, the second conductive member 42 has a protrusion 42p. The first conductive member 41 has a first recess 41r into which the protrusion 42p fits. However, this is not limited to such an embodiment. At least one of the first conductive member and the second conductive member may have a protrusion, and the other may have a first recess. For example, the first conductive member may have a protrusion, and the second conductive member may have a first recess into which the protrusion fits. Alternatively, both the first conductive member and the second conductive member may have a protrusion. In this case, the first conductive member and the second conductive member may each have a first recess into which the protrusion of the other fits.

[0054] However, from the viewpoint of fitting a protrusion provided on one conductive member into the other conductive member, it is preferable to provide the protrusion on the conductive member made of a metal with a higher Vickers hardness, between first conductive member 41 and second conductive member 42. From this viewpoint, it is preferable that second conductive member 42 has at least protrusion 42p.

[0055] Note that the first conductive member 41 and the second conductive member 42 may be provided with various connection configurations other than the first metal joint 45 and the second metal joint 46 described above.

[0056] As shown in FIG. 9 , the first conductive member 41 has a second recess 41R. The second recess 41R is formed in approximately the center of the first surface 41a of the first conductive member 41. The second recess 41R is a portion where at least a portion of the flange portion 42f is disposed. In this embodiment, the large diameter portion 42fa and the small diameter portion 42fb of the flange portion 42f are disposed in the second recess 41R. The second recess 41R has a shape corresponding to the large diameter portion 42fa and the small diameter portion 42fb. The first conductive member 41 has the second recess 41R that accommodates the flange portion 42f of the second conductive member 42, which can suppress relative movement between the first conductive member 41 and the second conductive member 42. As a result, the bonding of the metal joints 45, 46 is more likely to be maintained, and the reliability of the negative electrode terminal 40 can be improved.

[0057] Here, the area of ​​the second recess 41R is larger than the area of ​​the first recess 41r when viewed along the extension direction of the shaft portion 42s of the second conductive member 42. Therefore, the first recess 41r of the first conductive member 41 can be provided at least at one of the first bottom surface 41R1 and the second bottom surface 41R2 described below. Furthermore, it is preferable that the second conductive member 42 has at least one of the first recess and the protrusion 42p in a region disposed within the second recess 41R. This configuration makes it easier to maintain the bond between the metal joints 45, 46.

[0058] In this embodiment, the second recess 41R has a first bottom surface 41R1 and a second bottom surface 41R2 that are different in depth. The first bottom surface 41R1 is located deeper than the second bottom surface 41R2. Here, the first bottom surface 41R1 is located at the deepest position of the second recess 41R. In other words, the first bottom surface 41R1 is located at the position farthest from the opening 41R3 of the second recess 41R. The first bottom surface 41R1 is a substantially circular surface and has a shape corresponding to the upper surface 42u1 of the small diameter portion 42fb of the flange portion 42f of the second conductive member 42. The second bottom surface 41R2 is located between the first bottom surface 41R1 and the opening 41R3. The second bottom surface 41R2 is a substantially annular surface and has a shape corresponding to the upper surface 42u of the large diameter portion 42fa of the flange portion 42f.

[0059] The second recess 41R is recessed in a generally circular shape with a generally constant diameter from the opening 41R3 toward the second bottom surface 41R2. The large-diameter portion 42fa has an outer diameter corresponding to the inner diameter of the second recess 41R on the side closer to the opening 41R3 than the second bottom surface 41R2. In other words, the large-diameter portion 42fa is a generally disk-shaped portion having a diameter substantially equal to the inner diameter of the second recess 41R from the opening 41R3 to the first bottom surface 41R1. In this embodiment, the thickness of the large-diameter portion 42fa is set slightly larger than the length from the second bottom surface 41R2 to the opening 41R3. Therefore, the large-diameter portion 42fa protrudes slightly downward from the first surface 41a of the first conductive member 41. The dimensional relationship between the large-diameter portion 42fa and the second recess 41R in the height direction is not limited to this dimensional relationship.

[0060] From the second bottom surface 41R2 to the first bottom surface 41R1, the second recess 41R is recessed in a generally truncated cone shape. The second bottom surface 41R2 protrudes inward relative to the first bottom surface 41R1. Therefore, the side surface of the second recess 41R tapers so that the diameter gradually narrows from the first bottom surface 41R1 to the second bottom surface 41R2. In other words, the side surface of the second recess 41R tapers so that the diameter gradually increases from the second bottom surface 41R2 to the first bottom surface 41R1.

[0061] The first conductive member 41 and the second conductive member 42 may be mechanically fastened together. In this embodiment, the second conductive member 42 is mechanically fastened to the second recess 41R of the first conductive member 41. The flange portion 42f has a fastening portion 43 that is mechanically fastened to the first conductive member 41.

[0062] The fastening portion 43 is realized between the small diameter portion 42fb of the flange portion 42f and the first bottom surface 41R1 and the second bottom surface 41R2 of the second recess 41R. Here, the small diameter portion 42fb of the flange portion 42f is fitted into the side peripheral surface between the first bottom surface 41R1 and the second bottom surface 41R2 that protrudes inward within the second recess 41R of the first conductive member 41. In other words, the small diameter portion 42fb of the flange portion 42f is press-fitted into the second recess 41R of the first conductive member 41 and crimped to the side peripheral surface between the second bottom surface 41R2 and the first bottom surface 41R1. By mechanically fastening the first conductive member 41 and the second conductive member 42, the first conductive member 41 and the second conductive member 42 are firmly fastened together, which can improve the reliability of the negative terminal 40.

[0063] The form of the fastening portion 43 is not particularly limited as long as it is mechanically fastened by, for example, mechanical energy. The fastening portion 43 may be a portion fastened by, for example, press fitting, shrink fitting, caulking, riveting, folding, bolting, or the like.

[0064] In this embodiment, the flange portion 42f has a groove 42fc on its outer peripheral side surface. The groove 42fc is a portion of the flange portion 42f that is narrowed, and is also referred to as a narrowed portion. A portion of the first conductive member 41 is disposed in the groove 42fc. This configuration more firmly fastens the first conductive member 41 and the second conductive member 42, improving the reliability of the negative electrode terminal 40. The groove 42fc is formed at the boundary between the large diameter portion 42fa and the small diameter portion 42fb. The groove 42fc may be formed continuously, intermittently, or partially along the circumferential direction of the flange portion 42f. The groove 42fc is preferably formed continuously in an annular shape along the circumferential direction of the flange portion 42f. In this embodiment, the groove 42fc is continuous in the circumferential direction, and the outer peripheral edge of the narrowest portion (narrowed portion) of the groove 42fc is circular. The ratio of the length of the groove 42fc to the circumferential length is preferably 0.5 or more, more preferably 0.7 or more, and even more preferably 0.9 or more. Here, the circumferential length refers to the circumferential length of the portion of the side circumferential surface of the flange portion 42f where the groove 42fc is formed.

[0065] The fastening portion 43 is disposed at a position away from the end C1 of the contact portion C. In this embodiment, the end C1 of the contact portion C is the position where the opening 41R3 of the second recess 41R of the first conductive member 41 is formed. The end C1 is a portion exposed from the contact surface between the first conductive member 41 and the second conductive member 42. From the viewpoint of suppressing corrosion due to an electrolyte, water, or the like, the fastening portion 43 is preferably disposed at a position away from the end C1 of the contact portion C. The shortest creepage distance between the fastening portion 43 and the end C1 of the contact portion C is, for example, preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 5 mm or more. Here, the creepage distance is the distance along the contact portion C. In this embodiment, it is the distance from the opening 41R3 of the second recess 41R of the first conductive member 41 to the base end of the small diameter portion 42fb of the second conductive member 42, and is the distance along the inner circumferential side surface of the first conductive member 41 or the outer circumferential side surface of the second conductive member 42.

[0066] Similarly, from the viewpoint of suppressing corrosion due to the electrolyte or water, the second metal joint 46 is preferably disposed at a position away from the end C1 of the contact portion C. The shortest creepage distance between the second metal joint 46 and the end C1 of the contact portion C is, for example, preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 5 mm or more. Furthermore, the second metal joint 46 is preferably provided more inward than the fastening portion 43.

[0067] <Method of manufacturing negative electrode terminal 40> The above-described negative electrode terminal 40 can be manufactured, for example, by the manufacturing method of a terminal for an electric storage device (in this embodiment, the negative electrode terminal 40) described below. The manufacturing method of the terminal for an electric storage device includes a preparation step of preparing the first conductive member 41 and the second conductive member 42, a fastening step of fastening the first conductive member 41 and the second conductive member 42 together, and a metal joining step of metal-joining the first conductive member 41 and the second conductive member 42 together. The manufacturing method of the terminal for an electric storage device may include other steps.

[0068] In the preparation step, a first conductive member 41 and a second conductive member 42 are prepared. A second metal having the shape described above is prepared as the second conductive member 42. In this embodiment, a metal having lower rigidity than the second conductive member 42 is used as the first conductive member 41. The first conductive member 41 is prepared in a shape that deforms along the large diameter portion 42fa, the small diameter portion 42fb, and the groove 42fc of the second conductive member 42 when it is crimped in the fastening step.

[0069] In the fastening step, the first conductive member 41 and the second conductive member 42 are mechanically fastened together. In this embodiment, the first conductive member 41 and the second conductive member 42 are mechanically fastened together by crimping the first conductive member 41 to the second conductive member 42.

[0070] In the fastening process, first, the first conductive member 41 is placed in a mold (not shown). In this embodiment, the second conductive member 42 is pressed against the first conductive member 41 so that the flange portion 42f of the second conductive member 42 is inserted into the second recess 41R of the first conductive member 41. At this time, a known pressing device (not shown) or the like may be used. The first conductive member 41 is crushed because it has lower rigidity than the second conductive member 42, and is plastically deformed along the second conductive member 42. The edge of the second recess 41R of the first conductive member 41 is press-fitted into the groove 42fc of the second conductive member 42, and the first conductive member 41 and the second conductive member 42 are fastened together. In the fastening process, as described above, various fastening methods for mechanically fastening the first conductive member 41 and the second conductive member 42 can be employed.

[0071] A protrusion 42p is provided on the second conductive member 42. When the second conductive member 42 is pressed against the first conductive member 41 in the fastening step, the protrusion 42p may sink into the first conductive member 41, and a first recess 41r may be formed in the first conductive member 41.

[0072] After the first conductive member 41 and the second conductive member 42 are fastened together to form the fastening portion 43, the first conductive member 41 and the second conductive member 42 are then metal-joined.

[0073] In the metal joining process, a first metal joint 45 is formed at the interface between the first conductive member 41 and the second conductive member 42. In this embodiment, the first conductive member 41 and the second conductive member 42 are metal-joined using an ultrasonic joint. Although detailed illustration is omitted, in the metal joining process, the fastened first conductive member 41 and second conductive member 42 are sandwiched between a horn and anvil, and ultrasonic vibration is applied to the joining interface via the horn. For example, an anvil may be inserted into the cylindrical portion of the shaft portion 42s of the second conductive member 42, and ultrasonic vibration may be applied to the first conductive member 41 while pressing the horn against approximately the center of the second surface 41b of the first conductive member 41. As a result, the first metal joint 45 is formed approximately at the center of the interface between the first bottom surface 41R1 of the second recess 41R of the first conductive member 41 and the upper surface 42u1 of the small diameter portion 42fb of the second conductive member 42. When the horn is pressed against the first conductive member 41, the first conductive member 41 is pressed against the second conductive member 42. As a result, the protrusion 42p may sink into the first conductive member 41, and a first recess 41r may be formed in the first conductive member 41.

[0074] In the metal bonding process, ultrasonic vibrations are applied to the first conductive member 41, causing the first conductive member 41 to vibrate at the contact interface between the first recess 41r of the first conductive member 41 and the protrusion 42p of the second conductive member 42. This forms a second metal bond 46 at the contact interface between the first recess 41r and the protrusion 42p. From the viewpoint of facilitating the formation of the second metal bond 46, it is preferable that the protrusion have a tapered shape (a shape with a small area at the tip) toward the tip.

[0075] The closer to the position where the horn is applied, the easier it is for the ultrasonic vibrations applied by the horn to be transmitted. Therefore, the closer the position where second metal joint 46 is formed is to the position where the horn is applied (in this embodiment, approximately the center of second surface 41b of first conductive member 41), the easier it is to form a good second metal joint 46.

[0076] In the above-described embodiment, the second conductive member 42 prepared in the preparation step is provided with a protrusion 42p in advance. However, this is not limited to this embodiment, and the first conductive member prepared in the preparation step may be provided with a protrusion in advance. Furthermore, in the preparation step, a first recess may be provided in advance in at least one of the first conductive member and the second conductive member. In the fastening step, a protrusion that matches the first recess of one of the first conductive member and the second conductive member may be formed in the other of the first conductive member and the second conductive member. However, from the viewpoint of making it easier to form a second metal joint by ultrasonic vibration, it is preferable that a protrusion be provided in advance at the position where the second metal joint is to be formed.

[0077] The configuration of the negative electrode terminal 40 is not limited to the above-described embodiment. Fig. 10 is a cross-sectional view of a negative electrode terminal 40A according to another embodiment. Fig. 11 is a cross-sectional view of a negative electrode terminal 40B according to another embodiment. Fig. 12 is a cross-sectional view of a negative electrode terminal 40C according to another embodiment. In Figs. 10 to 12, components common to the above-described negative electrode terminal 40 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0078] In the negative electrode terminal 40A shown in Fig. 10, the protrusion 42p is provided at a position away from the small diameter portion 42fb. Therefore, compared to the negative electrode terminal 40 (see Fig. 9), the first recess 41r is formed at a position farther away from the central axis CL. Therefore, compared to the negative electrode terminal 40, a structure in which the protrusion 42p and the first recess 41r fit together is formed at a position farther away from the central axis CL. This can improve durability against a load applied in a direction that rotates the first conductive member 41 relative to the second conductive member 42.

[0079] 11, a recess 41b1 is formed in the approximate center of the second surface 41b of the first conductive member 41. Therefore, in the metal joining process, the distance between the position where the horn touches the bottom of the recess 41b1 and the contact portion C is reduced. This allows ultrasonic vibrations to be easily transmitted to the interface between the first conductive member 41 and the second conductive member 42, and can improve the joining strength of the first metal joint 45.

[0080] The protrusion 42p of the second conductive member 42 is provided on the upper surface 42u1 of the small diameter portion 42fb. Therefore, in the metal joining process, the position where the horn is applied to the first conductive member 41 is close to the protrusion 42p and the first recess 41r. This makes it easier for ultrasonic vibrations to be transmitted to the interface between the protrusion 42p and the first recess 41r, which can improve the joining strength of the second metal joint 46.

[0081] The small diameter portion 42fb of the second conductive member 42 extends radially outward beyond the shaft portion 42s. Therefore, the difference in diameter between the large diameter portion 42fa and the small diameter portion 42fb is smaller than in the negative terminal 40 (see FIG. 9). This increases the circumferential length of the groove 42fc, and also increases the length over which the fastening portion 43 is formed. As a result, the first conductive member 41 and the second conductive member 42 can be mechanically fastened together more firmly.

[0082] 12, the cross section of the protrusion 42p1 is substantially triangular in the circumferential direction of the flange portion 42f. Because the tip of the protrusion 42p1 has a pointed shape in the cross section along the circumferential direction of the flange portion 42f, ultrasonic vibrations are easily applied to the interface between the first conductive member 41 and the second conductive member 42 while they are in contact with each other. As a result, the second metal joint 46 is easily formed.

[0083] The technology disclosed herein has been described in various ways. Unless otherwise specified, the embodiments and the like described herein do not limit the present invention. Furthermore, the technology disclosed herein can be modified in various ways, and as long as no particular problems arise, each component and each process described herein can be omitted or combined as appropriate. Furthermore, this specification includes the disclosures described in the following sections.

[0084] Section 1: a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal for a power storage device, comprising: the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, the second conductive member has a first metal joint portion on an upper surface of the flange portion that is metal-jointed to the first conductive member, the second conductive member has at least one of a first recess and a protrusion on an outer circumferential side of the first metal joint portion, the first conductive member has at least one of the first recess and the protrusion fitted into the other of the first recess and the protrusion, the second conductive member has a second metal joint portion where the first conductive member and the second conductive member are metal-jointed at the first recess and the protrusion; Terminal for power storage device.

[0085] Section 2: the first conductive member has a second recess; Item 2. The terminal for a power storage device according to item 1, wherein at least a portion of the flange portion is disposed within the second recess.

[0086] Section 3: 3. The terminal for a power storage device according to item 1 or 2, wherein the flange portion has a fastening portion that is mechanically fastened to the first conductive member.

[0087] Section 4: The flange portion has a groove on an outer peripheral side surface, 3. The terminal for a power storage device according to item 2, wherein a portion of the first conductive member is disposed in the groove.

[0088] Section 5: a contact portion where the first conductive member and the second conductive member come into contact; Item 5. The terminal for a power storage device according to any one of items 1 to 4, wherein the second metal joint portion is disposed at a position away from an end of the contact portion.

[0089] Item 6: an electrode assembly including a positive electrode and a negative electrode; a case for accommodating the electrode assembly; a terminal electrically connected to the positive electrode or the negative electrode and attached to the case; Equipped with The terminal is a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal including: the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, the second conductive member has a first metal joint portion on an upper surface of the flange portion that is metal-jointed to the first conductive member, the second conductive member has at least one of a first recess and a protrusion on an outer circumferential side of the first metal joint portion, the first conductive member has at least one of the first recess and the protrusion fitted into the other of the first recess and the protrusion, the second conductive member has a second metal joint portion where the first conductive member and the second conductive member are metal-jointed at the first recess and the protrusion; Energy storage device. [Explanation of symbols]

[0090] 10 Electrode body 11 Positive electrode current collector 12 Negative electrode current collector 13 Positive electrode current collecting member 14 Negative electrode current collecting member 20 cases 22 Exterior body 22d bottom 22h opening 24 Sealing plate 24h terminal mounting hole 30 Positive terminal 40,40A~40C negative terminal 40c Crimped part 41 First conductive member 41a 1st page 41b 2nd side 41r 1st recess 41R 2nd recess 41R1 1st bottom 41R2 2nd bottom 41R3 opening 41ri rib 42 second conductive member 42d Bottom surface 42f flange 42fa large diameter section 42fb Small diameter section 42fc groove 42p protrusion 42s shaft part 42u top 42u1 top surface 43 Fastening part 45 1st metal joint (metal joint) 46 Second metal joint (metal joint) 48 External conductive members 48a Busbar weld 50 gaskets 60 insulator 90 Busbar 100 Electricity storage device 200 battery packs C Contact part C1 end CL center axis

Claims

1. a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal for a power storage device, comprising: the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, the second conductive member has a first metal joint portion on an upper surface of the flange portion that is metal-jointed to the first conductive member, the second conductive member has at least one of a first recess and a protrusion on an outer circumferential side of the first metal joint portion, the first conductive member has at least one of the first recess and the protrusion fitted into the other of the first recess and the protrusion, the second conductive member has a second metal joint portion where the first conductive member and the second conductive member are metal-jointed at the first recess and the protrusion; Terminal for power storage device.

2. the first conductive member has a second recess; The terminal for use with an electric storage device according to claim 1 , wherein at least a portion of the flange portion is disposed within the second recess.

3. The terminal for a power storage device according to claim 1 , wherein the flange portion has a fastening portion that is mechanically fastened to the first conductive member.

4. The flange portion has a groove on an outer peripheral side surface, The power storage device terminal according to claim 2 , wherein a portion of the first conductive member is disposed in the groove.

5. a contact portion where the first conductive member and the second conductive member come into contact; The terminal for a power storage device according to claim 1 or 2, wherein the second metal joint portion is disposed at a position away from an end of the contact portion.

6. an electrode assembly including a positive electrode and a negative electrode; a case for accommodating the electrode assembly; a terminal electrically connected to the positive electrode or the negative electrode and attached to the case; Equipped with The terminal is a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal including: the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, the second conductive member has a first metal joint portion on an upper surface of the flange portion that is metal-jointed to the first conductive member, the second conductive member has at least one of a first recess and a protrusion on an outer circumferential side of the first metal joint portion, the first conductive member has at least one of the first recess and the protrusion fitted into the other of the first recess and the protrusion, the second conductive member has a second metal joint portion where the first conductive member and the second conductive member are metal-jointed at the first recess and the protrusion; Energy storage device.

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