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 40 includes a first conductive member 41 and a second conductive member 42. The first conductive member 41 has a first recessed part 41R in a first surface 41a. The second conductive member 42 has a flange part 42f and a shaft part 42s. At least a part of the flange part 42f is arranged in the first recessed part 41R. The first conductive member 41 has a metal joint part 45 metal-joined to the flange part 42f. The flange part 42f has a larger-diameter part 42fa and a smaller-diameter part 42fb. The outer diameter of the small-diameter part 42b is 9 / 10 of the outer shape of the larger-diameter unit 42fa at a maximum. The outer periphery side surface of the smaller-diameter part 42fb has a fastening part 43 mechanically fastened to the inner surface of the first recessed part 41R.SELECTED DRAWING: Figure 3

Description

[Technical field]

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

[0002] JP 2022-049726 A discloses a terminal including a plate-shaped metal first member and a metal second member ultrasonically welded to one surface of the first member. A recess is formed in the surface of the first member 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] JP 2022-049726 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present inventors wish to further improve the reliability of connections between a plurality of members in a terminal for an electricity storage device in which the 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 first conductive member has a first recess on a first surface. The second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion. At least a part of the flange portion is disposed within the first recess. The first conductive member has a metal joint portion metal-joined to the flange portion. The flange portion has a large diameter portion and a small diameter portion. The outer diameter of the small diameter portion is 9 / 10 or less of the outer shape of the large diameter portion. The small diameter portion is located farther from the shaft portion than the large diameter portion. An outer peripheral side surface of the small diameter portion has a fastening portion mechanically fastened to an inner surface of the first recess. An upper surface of the large diameter portion is in contact with the first conductive member.

[0006] In this power storage device terminal, the connection between the first conductive member and the second conductive member has high reliability. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a perspective view of the electricity storage device 100. As shown in FIG. [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Diagram 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. [Diagram 5] FIG. 5 is a schematic diagram of the external conductive member 48. [Figure 6] FIG. 6 is a cross-sectional view of the negative electrode terminal 40. [Figure 7] FIG. 7 is a perspective view of the second conductive member 42. As shown in FIG. [Figure 8] FIG. 8 is a schematic diagram of the protrusion 42p. [Figure 9] FIG. 9 is a schematic diagram of a protrusion 42p according to another embodiment. [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. [Figure 13] FIG. 13 is a cross-sectional view of a negative electrode terminal 40D according to another embodiment. [Figure 14] FIG. 14 is a cross-sectional view of a negative electrode terminal 40E according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, an embodiment of the technology disclosed herein will be described with reference to the drawings. The embodiment described herein is, of course, not intended to limit the present invention in particular. Each drawing is drawn diagrammatically and does not necessarily reflect the actual product. In addition, the same reference numerals are appropriately used for members and parts that perform the same function, and duplicated descriptions are appropriately omitted. 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 storage device, respectively. However, these are merely directions for convenience of description, and do not limit the installation form of the storage device in any way.

[0009] In this specification, the term "electricity storage device" refers to all electricity storage devices capable of extracting electric 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 for a lithium ion secondary battery.

[0010] <Electricity storage device 100> FIG. 1 is a perspective view of an electricity storage device 100. FIG. 2 is a schematic longitudinal 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 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 electricity storage devices 100 disclosed herein are connected in series via bus bars 90, with the electricity storage device 100 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 those of conventional devices. The energy storage device 100 is preferably a secondary battery, and 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 here. 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 body 10 may be the same as a conventional one, and is not particularly limited. The electrode body 10 includes a positive electrode and a negative electrode (not shown). The electrode body 10 is, for example, a flat wound electrode body 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 body 10 may be a laminated electrode body 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 (for example, a lithium transition metal complex 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 (for example, 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 long side direction X of the electrode body 10, in which the positive electrode mixture layer and the negative electrode mixture layer are laminated in an insulated state. Meanwhile, at the left end of the long side direction X of the electrode body 10, a part of the positive electrode current collector 11 where the positive electrode mixture layer is not formed (positive electrode current collector exposed portion) protrudes from the laminated portion. A positive electrode current collector member 13 is attached to the positive electrode current collector exposed portion. The positive electrode current collector member 13 may be made of the same metal material as the positive electrode current collector 11, for example, a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode current collector member 13 is disposed in the case 20. The positive electrode current collector member 13 electrically connects the positive electrode and the positive electrode terminal 30.

[0015] In addition, at the right end of the long side direction X of the electrode body 10, a part of the negative electrode current collector 12 on which the negative electrode mixture layer is not formed (negative electrode current collector exposed part) protrudes from the laminated part. A negative electrode current collector 14 is attached to the negative electrode current collector exposed part. 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 that of 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 in 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 that used in the past and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (non-aqueous electrolyte) 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 body 10.

[0017] The case 20 is a housing that houses the electrode body 10. Here, the case 20 is formed in a flat, bottomed rectangular parallelepiped (rectangular). However, the shape of the case 20 is not limited to a rectangular shape, and may be any shape such as a cylinder. The material of the case 20 may be the same as that used conventionally, and is not particularly limited. 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 (for example, 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] The exterior body 22 has a bottom surface 22d. The sealing plate 24 faces the bottom surface 22d of the exterior body 22. The sealing plate 24 is attached to the exterior body 22 so as to close the opening 22h of the exterior body 22. The sealing plate 24 here has a substantially rectangular shape. Note that in this specification, the term "substantially rectangular shape" includes not only a perfect rectangular shape (rectangular shape) but also, for example, a shape in which the corners connecting the long and short sides of the rectangle are rounded, a shape in which the corners have notches, and the like.

[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 body 10 through the positive electrode current collector 13 inside the case 20. The negative electrode terminal 40 is electrically connected to the negative electrode of the electrode body 10 through the 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). It is preferable that the positive electrode terminal 30 and the negative electrode terminal 40 are 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 through 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 electricity 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. 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, the word "negative electrode" can be appropriately read as "positive electrode".

[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 is circular (for example, a perfect circle) in a plan view. The terminal mounting hole 24h has an inner diameter large enough to insert a crimped portion 40c of the negative electrode terminal 40 before crimping, which will be described later. The terminal mounting hole 24h is formed smaller than a flange portion 42f of the negative electrode terminal 40, which will be described later.

[0023] The negative current collecting member 14 is attached to the negative current collecting exposed portion of the negative current collecting body 12, and constitutes a conductive path that electrically connects the negative electrode and the negative terminal 40. The negative current collecting member 14 has a flat plate-shaped portion 14f that spreads horizontally along the inner surface of the sealing plate 24. The flat plate-shaped 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 insert a crimped portion 40c of the negative terminal 40 before crimping, which will be described later. The negative current collecting member 14 is fixed to the sealing plate 24 together with the negative terminal 40 by crimping. It is preferable that a resin insulating member is disposed between the case 20 (the sealing plate 24 in this embodiment) and the negative current collecting member 14. In this embodiment, the negative current collecting member 14 is fixed to the sealing plate 24 together with the negative terminal 40 in a state of being insulated via the 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., gasket 50) is preferably disposed between the case 20 (e.g., sealing plate 24) and the negative electrode terminal 40. The gasket 50 here has a function of insulating the sealing plate 24 from the negative electrode terminal 40 and closing 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 before crimping can be inserted therethrough. The tubular portion 51 is inserted into a 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 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 spreads 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 insert the shaft portion 42s of the negative electrode terminal 40. The insulator 60 is made of a resin material that has resistance to the electrolyte used and electrical insulation properties, and is elastically deformable, for example, a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA) or polyphenylene sulfide resin (PPS). The flat 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 up-down direction Z by crimping.

[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 on the outside of the case 20.

[0028] The negative electrode terminal 40 has 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 a metal joint 45.

[0029] The negative terminal 40 is inserted into the terminal mounting hole 24h of the sealing plate 24 and the opening 14h of the negative current collector 14, and the leading end in the insertion direction is crimped onto the negative current collector 14. More specifically, the leading end is crimped to the peripheral portion surrounding the opening 14h of the negative current collector 14. A crimped portion 40c is formed at the lower end of the negative terminal 40. The negative terminal 40 is fixed to the sealing plate 24 by crimping and is electrically connected to the negative current collector 14. The crimped portion 40c is cylindrical here. 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 is welded to the negative current collector 14. The first conductive member 41 and the second conductive member 42 constituting the negative 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. The first conductive member 41 is made of aluminum here. The first conductive member 41 is preferably made of a metal having a lower Vickers hardness (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 having the same metal element as the first component (the component having the highest mixing ratio by mass; the same applies below).

[0031] The first conductive member 41 preferably has a diameter larger than its thickness. In this embodiment, the first conductive member 41 is plate-shaped (specifically, flat). 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 to be joined to the second conductive member 42.

[0032] The first conductive member 41 has a first recess 41R on the first surface 41a. The first recess 41R is formed in the approximate center of the first surface 41a of the first conductive member 41. The first recess 41R is a portion where at least a part of the flange portion 42f is arranged. The first recess 41R preferably has a portion of the flange portion 42f, which will be described later, where the small diameter portion 42fb is arranged inside, and a portion where the large diameter portion 42fa is arranged inside. The first recess 41R preferably includes at least a portion where the small diameter portion 42fb is arranged inside. In this embodiment, the first recess 41R has a part of the large diameter portion 42fa and the small diameter portion 42fb arranged inside. The first recess 41R has a shape according to the small diameter portion 42fb and the large diameter portion 42fa. Therefore, a part of the outer peripheral side surface of the large diameter portion 42fa is in contact with the inner peripheral side surface of the first recess 41R of the first conductive member 41. In this manner, it is preferable that the inner peripheral side surface of the first recess 41R of the first conductive member 41 be disposed radially outward of the outer peripheral side surface of the large diameter portion 42fa of the second conductive member 42.

[0033] The shape of the first recess 41R is not particularly limited, but in this embodiment, the first recess 41R has a first bottom surface 41R1 and a second bottom surface 41R2 with different depths. The first bottom surface 41R1 is provided at a position deeper than the second bottom surface 41R2. Here, the first bottom surface 41R1 is provided at the deepest position of the first recess 41R. In other words, the first bottom surface 41R1 is provided at a position farthest from the opening 41R3 of the first 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 provided 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.

[0034] The first recess 41R is recessed from the opening 41R3 toward the second bottom surface 41R2 in a substantially circular shape with a substantially constant diameter. The large diameter portion 42fa has an outer diameter according to the inner diameter of the first 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 substantially disk-shaped portion having a diameter substantially equal to the inner diameter of the first 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 to be 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 first recess 41R in the height direction is not limited to such a dimensional relationship.

[0035] From the second bottom surface 41R2 to the first bottom surface 41R1, the first recess 41R is recessed in a substantially truncated cone shape. The second bottom surface 41R2 protrudes inward from the first bottom surface 41R1. Therefore, the side surface of the first 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 first recess 41R tapers so that the diameter gradually increases from the second bottom surface 41R2 to the first bottom surface 41R1.

[0036] 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).

[0037] As shown in FIG. 4, when the assembled battery 200 is fabricated, a bus bar 90 is connected to the external conductive member 48 connected to the first conductive member 41. FIG. 5 is a schematic diagram of the external conductive member 48. In FIG. 5, the external conductive member 48 and the bus bar 90 are typically shown as viewed from above. In FIG. 5, the second conductive member 42 hidden by the external conductive member 48 is shown by a broken line. As shown in FIG. 5, the bus bar 90 is connected to the external conductive member 48 at a bus bar welded portion 48a. The bus bar 90 and the external conductive member 48 can be welded by, for example, laser welding or the like. 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 assembled battery 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 being interposed therebetween.

[0038] <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. Here, 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 that has the same metal element as the first component. A 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.

[0039] The second conductive member 42 has a flange portion 42f and a shaft portion 42s (connection portion). 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 the gasket 50 is disposed between the flange portion 42f and the sealing plate 24. A tube portion 51 of the gasket 50 is disposed between the shaft portion 42s and the sealing plate 24. The shaft portion 42s is expanded in diameter toward the tip. The expanded portion is connected to the negative current collecting member 14. The expanded portion is also referred to as a crimped portion 40c, and is preferably crimped and connected to the negative current collecting member 14 in a state where it is inserted into the opening 14h of the negative current collecting member 14. From the viewpoint of improving electrical conductivity, the crimped portion 40c and a part of the negative current collecting member 14 are preferably joined by laser welding or the like.

[0040] 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 whose diameter is wider than that of the shaft portion 42s. The flange portion 42f is a portion disposed outside the case 20. The flange portion 42f is connected to the first conductive member 41.

[0041] 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 a shape in which a notch is formed in a part of the outer circumferential surface. At least a part of the outer circumferential edge of the flange portion 42f is preferably circular. For example, in the thickness direction of the flange portion 42f, the shape of the outer circumferential edge going around at the same height is preferably circular.

[0042] Fig. 6 is a cross-sectional view of the negative electrode terminal 40. Fig. 6 shows a cross section near the interface between the first conductive member 41 and the second conductive member 42. Fig. 6 does not show the sealing plate 24, the gasket 50, the insulator 60, the negative electrode current collecting member 14, etc.

[0043] As shown in FIG. 6, the flange portion 42f has a large diameter portion 42fa and a small diameter portion 42fb. The large diameter portion 42fa is a portion having a larger diameter than the small diameter portion 42fb. The large diameter portion 42fa is a substantially disk-shaped portion having a substantially uniform 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. The small diameter portion 42fb protruding upward is formed in the substantially central portion of the upper surface 42u of the large diameter portion 42fa. The small diameter portion 42fb is located farther from the shaft portion 42s than the large diameter portion 42fa. The large diameter portion 42fa and the small diameter portion 42fb are shaped along the first recess 41R. The small diameter portion 42fb has a larger diameter toward the tip side (the side farther from the flange portion 42f). The small diameter portion 42fb has a smaller diameter 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.

[0044] The negative electrode terminal 40 has a contact portion C where the first conductive member 41 and the second conductive member 42 are in contact. At least a portion of the flange portion 42f is disposed in the first recess 41R. A portion of the flange portion 42f of the second conductive member 42 is in contact with the first conductive member 41 in the first recess 41R. At the contact portion C, the first conductive member 41 has a metal joint portion 45. The metal joint portion 45 is a joint portion where the first conductive member 41 and the flange portion 42f of the second conductive member 42 are joined by metal joining. The metal joint portion 45 is formed in the center of the upper surface of the flange portion 42f.

[0045] Here, metal bonding refers to bonding a plurality of metal members to each other by metallurgical bonding, and does not include bonding by mechanical fastening. The metal bonding portion 45 is preferably formed by ultrasonic bonding, diffusion bonding, laser welding, or the like. From the viewpoint of suppressing the formation of a brittle intermetallic compound at the bonding interface, the metal bonding portion 45 is preferably an ultrasonic bonding portion formed by ultrasonic bonding. In this embodiment, the metal bonding portion 45 is an ultrasonic bonding portion in which the first conductive member 41 and the second conductive member 42 are bonded by ultrasonic bonding.

[0046] In this embodiment, the 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 metal joint 45 is preferably formed by metal-joining the upper surface of the flange portion 42f and the bottom surface of the recess of the first conductive member 41 (in this embodiment, the first bottom surface 41R1 of the first recess 41R). It is more preferable that the metal joint 45 is formed in the center of the upper surface of the flange portion 42f.

[0047] The negative electrode terminal 40 has a fastening portion 43. The fastening portion 43 refers to a portion where the first conductive member 41 and the second conductive member 42 are mechanically fastened. The fastening portion 43 is formed by mechanically fastening the outer peripheral side surface of the small diameter portion 42fb to the inner surface of the first recess 41R. The fastening portion 43 is formed along the outer peripheral side surface of the small diameter portion 42fb.

[0048] 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 first 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 protruding inward in the first 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 first recess 41R of the first conductive member 41 and is crimped to the side peripheral surface between the second bottom surface 41R2 and the first bottom surface 41R1.

[0049] The form of the fastening portion 43 is not particularly limited as long as it is mechanically fastened by 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.

[0050] The upper surface 42u of the large diameter portion 42fa is in contact with the first conductive member 41. Here, the upper surface 42u refers to the surface in contact with the first conductive member 41, and is the surface opposite to the lower surface 42d from which the shaft portion 42s extends. In this embodiment, the upper surface 42u of the large diameter portion 42fa is in contact with the second bottom surface 41R2 of the first recess 41R of the first conductive member 41. This is not limited to the above embodiment, and the upper surface 42u of the large diameter portion 42fa may be in contact with, for example, the first surface 41a of the first conductive member 41. The surface where the upper surface 42u of the large diameter portion 42fa and the first conductive member 41 are in contact may vary depending on the shapes of the first conductive member 41 and the second conductive member 42, etc.

[0051] According to the findings of the present inventors, in a terminal for an electricity storage device having a fastening portion where a plurality of conductive members are mechanically fastened, the fastening portion may be damaged during use of the electricity storage device. For example, there is a concern that the fastening portion may be damaged if an event occurs in which an electrolyte comes into contact with a portion where the boundary between the conductive members is exposed due to vibration or the like during use of the electricity storage device.

[0052] In the negative electrode terminal 40, the outer diameter of the small diameter portion 42fb is set to be smaller than the outer diameter of the large diameter portion 42fa. By making the outer diameter of the small diameter portion 42fb smaller than the outer diameter of the large diameter portion 42fa, a distance is ensured between the fastening portion 43 formed on the outer peripheral side surface of the small diameter portion 42fb and the boundary portion between the first conductive member 41 and the second conductive member 42. Along the radial direction of the flange portion 42f, the length of contact between the upper surface 42u of the large diameter portion 42fa and the first conductive member 41 is increased. With this configuration, for example, even if the electrolyte comes into contact with the portion where the boundary between the first conductive member 41 and the second conductive member 42 is exposed due to vibration or the like during use of the electricity storage device 100, the electrolyte or water is less likely to reach the small diameter portion 42fb. As a result, the deterioration of the reliability of the fastening portion 43 due to corrosion of the interface between the first conductive member 41 and the second conductive member 42 in the fastening portion 43 is suppressed. According to the knowledge of the present inventors, when the outer diameter of the small diameter portion 42fb is 9 / 10 or less of the outer diameter of the large diameter portion 42fa, deterioration in the reliability of the fastening portion 43 is effectively suppressed.

[0053] The outer diameters of the large diameter portion 42fa and the small diameter portion 42fb refer to the outer shapes of the portions that have the largest diameters 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, so it refers to the outer diameter at any position in the axial direction.

[0054] For example, the outer diameter of the small diameter portion 42fb is more preferably 4 / 5 or less of the outer diameter of the large diameter portion 42fa, and even more preferably 2 / 3 or less. This further improves the reliability of the fastening portion 43. Also, for example, the difference between the outer diameter of the large diameter portion 42fa and the outer diameter of the small diameter portion 42fb is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. Note that the outer diameter of the small diameter portion 42fb is preferably 1 / 5 or more of the outer diameter of the large diameter portion 42fa. This further improves the reliability of the fastening portion 43.

[0055] 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 a 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 or water, 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 3 mm or more. Here, the creepage distance is a distance along the contact portion C. In this embodiment, it is a 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 a distance along the inner peripheral side surface of the first conductive member 41 or the outer peripheral side surface of the second conductive member 42.

[0056] In the above-described embodiment, the contact portion C is also formed on the outer circumferential side surface of the large diameter portion 42fa of the flange portion 42f. As a result, the shortest creepage distance between the fastening portion 43 and the end C1 of the contact portion C is longer by the length of the contact portion C on the outer circumferential side surface of the large diameter portion 42fa. This makes the fastening portion 43 less susceptible to corrosion by an electrolyte, water, or the like.

[0057] In a configuration in which the inner peripheral side surface of the first recess 41R is disposed radially outward of the outer peripheral side surface of the large diameter portion 42fa, a gap may be provided between the outer peripheral side surface of the large diameter portion 42fa and the inner peripheral side surface of the first recess 41R. This configuration can form a more stable fastening portion 43. Although not particularly limited, the gap between the outer peripheral side surface of the large diameter portion 42fa and the inner peripheral side surface of the first recess 41R may be, for example, 1 mm or less, or 0.5 mm or less.

[0058] Furthermore, the first conductive member 41 and the second conductive member 42 may be provided with various connection configurations other than the fastening portion 43 and the metal joint portion 45 described above.

[0059] In this embodiment, a groove 42fc is provided on the outer peripheral side surface of the flange portion 42f. The groove 42fc is a part of the flange portion 42f that is constricted, and is also referred to as a constricted portion. A part of the first conductive member 41 is disposed in the groove 42fc. With this configuration, the first conductive member 41 and the second conductive member 42 are more strongly fastened, and the reliability of the negative electrode terminal 40 can be improved. 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 along the circumferential direction of the flange portion 42f, may be formed intermittently, or may be formed partially. 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 thinnest part (constricted part) of the groove 42fc is circular. The length of the groove 42fc relative 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 above-mentioned circumferential length refers to the circumferential length at the portion of the side circumferential surface of the flange portion 42f where the groove 42fc is formed.

[0060] In this embodiment, the second conductive member 42 is provided with a protrusion 42p. The protrusion 42p is provided on the outer periphery side of the metal joint portion 45. The protrusion 42p is provided on the contact portion C between the first conductive member 41 and the second conductive member 42. The protrusion 42p is formed on the upper surface 42u of the large diameter portion 42fa of the upper surface of the flange portion 42f. The protrusion 42p is provided at a position away from the end C1 of the contact portion C in the second conductive member 42. The shortest creeping distance between the protrusion 42p and the end C1 of the contact portion C is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. The protrusion 42p is preferably provided on the inner diameter side of a position 0.9 times the diameter of the flange portion 42f from the center axis CL, more preferably 0.8 times the diameter, and even more preferably 0.6 times the diameter.

[0061] FIG. 7 is a perspective view of the second conductive member 42. FIG. 8 is a schematic diagram of the protrusion 42p. FIG. 9 is a schematic diagram of the protrusion 42p according to another embodiment. As shown in FIG. 7, the protrusion 42p is provided on the upper surface 42u of the large diameter portion 42fa in the vicinity of 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 provided along the radial direction from the base end of the small diameter portion 42fb.

[0062] The protrusion 42p is preferably provided on the upper surface 42u of the large diameter portion 42fa near the base of the small diameter portion 42fb. This can reduce the risk of corrosion of the interface between the protrusion 42p and the second recess 41r due to an electrolyte or water. For example, the protrusion 42p is preferably provided on the upper surface 42u of the large diameter portion 42fa within 5 mm from the base of the small diameter portion 42fb, more preferably within 3 mm, and even more preferably within 1 mm.

[0063] As shown in FIG. 8, 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 substantially trapezoidal. The shape of the protrusion 42p is not limited to this, and may have a pointed tip as shown in FIG. 9. The cross section of the protrusion 42p along the length direction may be substantially 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 by the height B of the protrusion 42p to the width A of the base end of the protrusion 42p, is 1 or more.

[0064] As shown in Figures 7 and 8, the protrusions 42p are formed along the radial direction. 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. Moreover, the length of the protrusions 42p in the radial direction is preferably 5 mm or less, and more preferably 3 mm or less.

[0065] 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 at approximately equal intervals in the circumferential direction. The number, arrangement, intervals, etc. of the protrusions 42p are not particularly limited. The number of the 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 the protrusions 42p is preferably more than one, and more preferably 4 or more. From the viewpoint of productivity, the number of the protrusions 42p may be, for example, 20 or less, 12 or less, or 8 or less.

[0066] As shown in FIG. 6, the protrusions 42p of the second conductive member 42 bite into the first conductive member 41. In other words, the first conductive member 41 has second recesses 41r that fit with the protrusions 42p of the second conductive member 42. The first conductive member 41 has the same number of second recesses 41r as the protrusions 42p of the second conductive member 42. The second recesses 41r are formed in the same positions as the protrusions 42p and in shapes corresponding to the protrusions 42p. In this way, the protrusions 42p of the second conductive member 42 and the second recesses 41r of the first conductive member 41 fit into the interface between the first conductive member 41 and the second conductive member 42. With this configuration, the first conductive member 41 and the second conductive member 42 can be more firmly fastened. Furthermore, even when an external connection member such as the bus bar 90 applies a force in the circumferential direction about the central axis CL of the negative terminal 40 (see FIG. 4), a load is unlikely to be applied in a direction that rotates the first conductive member 41 relative to the second conductive member 42. This makes it easier to maintain the metal joint 45 in the negative terminal 40, and can improve the reliability of conduction between the first conductive member 41 and the second conductive member 42. From this viewpoint, it is preferable that a plurality of second recesses 41r and protrusions 42p are provided.

[0067] A metal bond may be formed at the interface between the second recess 41r of the first conductive member 41 and the protrusion 42p of the second conductive member 42. This can improve the conductivity between the first conductive member 41 and the second conductive member 42.

[0068] In the above-described embodiment, the second conductive member 42 has a protrusion 42p. The first conductive member 41 has a second recess 41r into which the protrusion 42p fits. However, the present invention is not limited to such a form. At least one of the first conductive member and the second conductive member may have a protrusion, and the other may have a second recess. For example, the first conductive member may have a protrusion, and the second conductive member may have a second recess into which the protrusion fits. Also, 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 second recess into which the protrusion of the other fits.

[0069] However, from the viewpoint of fitting a protrusion provided on one conductive member into the other conductive member, it is preferable to provide it on the conductive member made of a metal having a larger 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.

[0070] The form of the fastening portion 43 is not particularly limited as long as it is mechanically fastened by 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.

[0071] <Method of Manufacturing Negative Electrode Terminal 40> The above-mentioned negative electrode terminal 40 can be manufactured, for example, by a manufacturing method for a terminal for an electricity storage device (in this embodiment, the negative electrode terminal 40) described below. The manufacturing method for a terminal for an electricity 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. The manufacturing method for a terminal for an electricity storage device may include other steps.

[0072] In the preparation step, a first conductive member 41 and a second conductive member 42 are prepared. A second metal having the above-mentioned shape is prepared as the second conductive member 42. In this embodiment, a metal having a 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.

[0073] In the fastening step, the first conductive member 41 and the second conductive member 42 are mechanically fastened to each other. In this embodiment, the first conductive member 41 and the second conductive member 42 are mechanically fastened to each other by crimping the first conductive member 41 to the second conductive member 42.

[0074] In the fastening step, first, the first conductive member 41 is placed in a die (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 first 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 a lower rigidity than the second conductive member 42, and is plastically deformed along the second conductive member 42. The edge of the first recess 41R of the first conductive member 41 is pressed 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 step, as described above, various fastening methods for mechanically fastening the first conductive member 41 and the second conductive member 42 can be adopted.

[0075] A gap may be provided between the outer peripheral side surface of the large diameter portion 42fa and the inner peripheral side surface of the first recess 41R. With this configuration, the large diameter portion 42fa can be easily inserted into the first recess 41R, and a stable fastening portion 43 can be easily formed.

[0076] The second conductive member 42 is provided with a protrusion 42p. When the second conductive member 42 is pressed against the first conductive member 41 in the fastening step, the protrusion 42p may be embedded in the first conductive member 41, and a second recess 41r may be formed in the first conductive member 41.

[0077] 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-jointed.

[0078] In the metal joining process, a 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 by an ultrasonic joint. Although detailed illustration is omitted, in the metal joining process, the fastened first conductive member 41 and the second conductive member 42 are sandwiched between a horn and an 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 the approximate center of the second surface 41b of the first conductive member 41. As a result, a metal joint 45 is formed at the approximate center of the interface between the first bottom surface 41R1 of the first 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 be pressed into the first conductive member 41, and a second recess 41r may be formed in the first conductive member 41.

[0079] In the metal bonding process, ultrasonic vibration is applied to the first conductive member 41, so that the first conductive member 41 can also vibrate at the contact interface between the second recess 41r of the first conductive member 41 and the protrusion 42p of the second conductive member 42. This can form a metal bond also at the contact interface between the second recess 41r and the protrusion 42p. From the viewpoint of facilitating the formation of a metal bond, it is preferable that the protrusion has a tapered shape (a shape with a small area at the tip) toward the tip.

[0080] The closer the position where the horn is applied, the easier it is for the ultrasonic vibration applied by the horn to be transmitted. Therefore, the closer the positions of the protrusion 42p and the second recess 41r are to the position where the horn is applied (in this embodiment, approximately the center of the second surface 41b of the first conductive member 41), the easier it is for a good metal joint to be formed at the interface between the protrusion 42p and the second recess 41r.

[0081] In the above-described embodiment, the second conductive member 42 prepared in the preparation step is provided with a protrusion 42p in advance. However, the present invention is not limited to this embodiment, and the first conductive member prepared in the preparation step may be provided with a protrusion in advance. In addition, in the preparation step, at least one of the first conductive member and the second conductive member may be provided with a first recess in advance. In the fastening step, the other of the first conductive member and the second conductive member may be formed with a protrusion that matches the first recess of one of the members. However, from the viewpoint of firmly fastening the protrusion 42p and the second recess 41r, it is preferable that a protrusion is provided in advance at a position where a second metal joint is to be formed.

[0082] The configuration of the negative electrode terminal 40 is not limited to the above-mentioned 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. Fig. 13 is a cross-sectional view of a negative electrode terminal 40D according to another embodiment. Fig. 14 is a cross-sectional view of a negative electrode terminal 40E according to another embodiment. In Figs. 10 to 14, configurations common to the above-mentioned negative electrode terminal 40 are denoted by the same reference numerals, and detailed description thereof will be omitted.

[0083] In the negative electrode terminal 40A shown in FIG. 10, the first recess 41R of the first conductive member 41 is set to a shape and dimensions such that only the small diameter portion 42fb of the flange portion 42f of the second conductive member 42 is disposed therein. The second bottom surface 41R2 (see FIG. 6) is not formed in the first recess 41R. The shape of the first recess 41R follows the shape of the small diameter portion 42fb. In this embodiment, the upper surface of the large diameter portion 42fa of the flange portion 42f is in contact with the first surface 41a of the first conductive member 41. The dimensional relationship between the large diameter portion 42fa of the second conductive member 42 and the first conductive member 41 in the radial direction of the flange portion 42f is not particularly limited. In this embodiment, the dimensions of the large diameter portion 42fa of the second conductive member 42 and the first conductive member 41 are set to be approximately the same. This allows the size of the small diameter portion 42fb to be increased and the depth of the first recess 41R to be deepened while maintaining the outer diameter of the negative electrode terminal 40A. This can increase the joint strength at the fastening portion 43. Furthermore, the electrical conductivity between the first conductive member 41 and the second conductive member 42 can be improved by increasing the ratio of the second conductive member 42 to the negative electrode terminal 40. As a result, heat generation during current flow can be suppressed, and the durability of the electricity storage device 100 can be improved.

[0084] In the negative electrode terminal 40B shown in FIG. 11, the protrusion 42p is provided on the upper surface 42u of the large diameter portion 42fa of the flange portion 42f. The protrusion 42p is provided in a substantially central portion between the peripheral edge portion of the large diameter portion 42fa and the base end of the small diameter portion 42fb. In this manner, the protrusion 42p does not necessarily have to be provided near the base of the small diameter portion 42fb. By providing the protrusion 42p at a position away from the base of the small diameter portion 42fb, durability against a load applied in a direction rotating the first conductive member 41 relative to the second conductive member 42 can be improved.

[0085] 12, the projection 42p is provided on the upper surface 42u1 of the small diameter portion 42fb of the flange portion 42f. With this configuration, the interface between the projection 42p and the second recess 41r is farther away from the end C1 of the contact portion C. As a result, corrosion of the interface between the projection 42p and the second recess 41r due to the electrolyte, water, or the like can be reduced.

[0086] In the negative electrode terminal 40D shown in Fig. 13 and the negative electrode terminal 40E shown in Fig. 14, the cross section of the protrusion 42p is substantially triangular in the circumferential direction of the flange portion 42f. In the cross section along the circumferential direction of the flange portion 42f, the tip of the protrusion 42p has a pointed shape, so that ultrasonic vibration is easily applied to the interface between the first conductive member 41 and the second conductive member 42 in a state of contact with each other. As a result, a metal bond is easily formed at the interface between the protrusion 42p and the second recess 41r.

[0087] The technology disclosed herein has been described above 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 each component and each process described herein can be omitted or combined as appropriate unless a particular problem occurs. Furthermore, this specification includes the disclosures described in the following sections.

[0088] 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 first conductive member has a first recess on a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, the first conductive member has a metal joint portion that is metal-jointed to the flange portion, The flange portion has a large diameter portion and a small diameter portion, The outer diameter of the small diameter portion is 9 / 10 or less of the outer diameter of the large diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer peripheral side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, An upper surface of the large diameter portion contacts the first conductive member. Terminal for power storage device.

[0089] Section 2: 2. The terminal for an energy storage device according to item 1, wherein a groove is provided on an outer circumferential side surface of the small diameter portion, and a part of the first conductive member is disposed within the groove.

[0090] Section 3: a contact portion where the first conductive member and the second conductive member come into contact with each other; 3. The terminal for an energy storage device according to item 1 or 2, wherein the fastening portion is disposed at a position away from an end of the contact portion.

[0091] Section 4: one of a protrusion and a second recess is provided at a position away from an end of the contact portion on the second conductive member, 4. The terminal for a power storage device according to item 3, wherein the first conductive member has one of the protrusion and the second recess fitted with the other of the protrusion and the second recess.

[0092] Section 5: 5. The terminal for an electric storage device according to item 4, wherein the second conductive member has one of the protrusion and the second recess on an upper surface of the large diameter portion and in the vicinity of a base of the small diameter portion.

[0093] Item 6: 6. The terminal for an electricity storage device according to any one of items 3 to 5, wherein the contact portion is also formed on an outer circumferential side surface of the large diameter portion of the flange portion.

[0094] Section 7: An electrode assembly including a positive electrode and a negative electrode; A case that accommodates 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 for a power storage device, comprising: the first conductive member has a first recess on a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, the first conductive member has a metal joint portion that is metal-jointed to the flange portion, The flange portion has a large diameter portion and a small diameter portion, The outer diameter of the small diameter portion is 9 / 10 or less of the outer diameter of the large diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer peripheral side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, An upper surface of the large diameter portion contacts the first conductive member. Energy storage device. [Explanation of symbols]

[0095] 10 Electrode body 11 Positive electrode current collector 12 Negative electrode current collector 13 Positive electrode current collector 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~40E Negative terminal 40c Crimping part 41 First conductive member 41a 1st page 41b 2nd side 41R 1st recess 41R1 1st bottom 41R2 2nd bottom 41R3 opening 41r 2nd recess 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 Metal joints 48 External conductive members 48a Busbar weld 50 Gasket 60 Insulator 90 Busbar 100 Electricity storage device 200 battery pack 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 first conductive member has a first recess on a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, the first conductive member has a metal joint portion that is metal-jointed to the flange portion, The flange portion has a large diameter portion and a small diameter portion, The outer diameter of the small diameter portion is 9 / 10 or less of the outer diameter of the large diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer circumferential side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, An upper surface of the large diameter portion contacts the first conductive member. Terminal for power storage device.

2. The terminal for an electric storage device according to claim 1 , wherein a groove is provided on an outer circumferential side surface of the small diameter portion, and a part of the first conductive member is disposed in the groove.

3. a contact portion where the first conductive member and the second conductive member come into contact with each other; The power storage device terminal according to claim 1 , wherein the fastening portion is disposed at a position away from an end of the contact portion.

4. one of a protrusion and a second recess is provided at a position away from an end of the contact portion on the second conductive member, The terminal for the power storage device according to claim 3 , wherein the first conductive member has one of the protrusion and the second recess fitted with the other of the protrusion and the second recess.

5. The power storage device terminal according to claim 4 , wherein the second conductive member has one of the protrusion and the second recess on an upper surface of the large diameter portion and in the vicinity of a base of the small diameter portion.

6. The power storage device terminal according to claim 3 , wherein the contact portion is also formed on an outer circumferential side surface of the large diameter portion of the flange portion.

7. An electrode assembly including a positive electrode and a negative electrode; A case that accommodates 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 for a power storage device, comprising: the first conductive member has a first recess on a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, the first conductive member has a metal joint portion that is metal-jointed to the flange portion, The flange portion has a large diameter portion and a small diameter portion, The outer diameter of the small diameter portion is 9 / 10 or less of the outer diameter of the large diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer circumferential side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, An upper surface of the large diameter portion contacts the first conductive member. Energy storage device.

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