Terminal for power storage device and manufacturing method of power storage device including the same

Abstract

To provide a manufacturing method of a terminal for a power storage device in which reliability of a connection part between a first conductive member and a second conductive member is high.SOLUTION: The invention provides a terminal 40 including a first conductive member 41 that is formed of a first metal and includes a concave part 41r, a second conductive member 42 that is formed of a second metal and includes a part disposed in the concave part 41r, and an ultrasonic bonding part 45 where the first conductive member 41 and the second conductive member 42 are bonded to each other with ultrasonic waves. The first conductive member 41 includes a rib 41s that is provided on an outer peripheral side relative to the ultrasonic bonding part 45 and that protrudes from a second surface 41u of the first conductive member 41.SELECTED DRAWING: Figure 5

Description

[Technical field]

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

[0002] Conventionally, terminals formed by joining conductive members (a first conductive member and a second conductive member) made of different metals have been known. For example, Patent Document 1 discloses a method for manufacturing a terminal including a fastening step of mechanically fastening the first conductive member and the second conductive member to form a fastening portion, and a metal joining step of metallically joining the first conductive member and the second conductive member to form a metal joint portion, as well as a method for manufacturing an electricity storage device including a crimping step of fixing the terminal to a battery case and a current collecting member by crimping. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2022-049729 A Summary of the Invention [Problem to be solved by the invention]

[0004] For example, in mechanical joining processes such as the fastening process and the crimping process, a load may be applied to the conductive member or the metal joint. This may cause the conductive member to deform or the metal joint to become damaged, making it difficult to stabilize the connection between the first conductive member and the second conductive member. This tendency was particularly noticeable when ultrasonically joining the first conductive member and the second conductive member to form an ultrasonic joint in the metal joining process, because it is preferable to perform the ultrasonic joining before the crimping process.

[0005] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a terminal for an energy storage device having an ultrasonic joint and a highly reliable connection between a first conductive member and a second conductive member, and a method for manufacturing an energy storage device including the same. [Means for solving the problem]

[0006] The present invention provides a terminal for an energy storage device comprising: a first conductive member made of a first metal and having a recess on a first surface; a second conductive member made of a second metal different from the first metal and having a portion disposed within the recess; and an ultrasonic joint at which the first conductive member and the second conductive member are ultrasonically joined, wherein the first conductive member is disposed outer circumferentially of the ultrasonic joint and has a rib protruding from a second surface of the first conductive member opposite the first surface.

[0007] With the above configuration, the connection between the first conductive member and the second conductive member becomes a highly reliable terminal. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view that illustrates a power storage device according to an embodiment. [Diagram 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 3 is a partially enlarged cross-sectional view that illustrates the vicinity of the negative electrode terminal. [Figure 4] FIG. 4 is a top view illustrating a schematic diagram of a negative electrode terminal according to one embodiment. [Diagram 5] FIG. 5 is a schematic vertical cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a vertical cross-sectional view that illustrates a schematic connection between the negative electrode terminal and an external conductive member. [Figure 7] FIG. 7 is a perspective view illustrating a schematic configuration of an electricity storage module according to one embodiment. [Figure 8] FIG. 8 is a vertical cross-sectional view that illustrates an example of the crimping step. [Figure 9] FIG. 9 is a view corresponding to FIG. 5 according to the first modified example. [Figure 10] FIG. 10 is a view corresponding to FIG. 5 according to the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the drawings. Note that matters other than those specifically mentioned in this specification and necessary for implementing the present invention (for example, the general configuration and manufacturing process of a power storage device that does not characterize the present invention) can be understood as design matters of a person skilled in the art based on the conventional technology in the field. The technology disclosed here can be implemented based on the contents disclosed in this specification and the technical common sense in the field.

[0010] <Electricity storage device 100> Fig. 1 is a perspective view of the energy storage device 100. Fig. 2 is a schematic vertical cross-sectional view taken along line II-II in Fig. 1. In the following description, the symbols L, R, U, and D in the drawings represent left, right, top, and bottom, and the symbols X, Y, and Z in the drawings represent the short side direction, long side direction perpendicular to the short side direction, and up-down direction, respectively, of the energy storage device 100. However, these directions are merely for the sake of convenience in the description, and do not limit the installation form of the energy storage device 100 in any way.

[0011] In this specification, the term "energy storage device" refers to any device that can be repeatedly charged and discharged, and is a concept that encompasses storage batteries such as lithium ion secondary batteries and nickel-metal hydride batteries, and capacitors such as lithium ion capacitors and electric double layer capacitors.

[0012] As shown in FIG. 2, the electricity storage device 100 includes an electrode assembly 10, a positive electrode current collector 13, a negative electrode current collector 14, a battery case 20, a positive electrode terminal 30, and a negative electrode terminal 40. The electricity 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 the conventional device. The electricity storage device 100 is preferably a secondary battery, and more preferably a non-aqueous electrolyte secondary battery. Here, the electricity storage device 100 is a lithium ion secondary battery. Although not shown, the electricity storage device 100 further includes an electrolyte. The electricity storage device 100 is configured by housing the electrode assembly 10 and an electrolyte (not shown) in a battery case 20.

[0013] The electrode body 10 may be the same as a conventional one, and is not particularly limited. The electrode body 10 has 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. One of the positive electrode and the negative electrode is an example of a "first electrode", and the other is an example of a "second electrode". Among them, it is preferable that the negative electrode is the "first electrode".

[0014] 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).

[0015] As shown by the diagonal lines in FIG. 2, a laminated portion is formed in the center of the long side direction Y 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 Y 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 electrically connects the positive electrode and the positive electrode terminal 30 inside the battery case 20.

[0016] At the right end of the electrode body 10 in the long side direction Y, 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 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 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 electrically connects the negative electrode and the negative electrode terminal 40 inside the battery case 20.

[0017] 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.

[0018] The battery case 20 is a housing that houses the electrode body 10. Here, the battery case 20 is formed in a flat, bottomed rectangular parallelepiped (rectangular) shape. However, the shape of the battery case 20 is not limited to a rectangular shape, and may be any shape such as a cylinder. The material of the battery case 20 may be the same as that used conventionally, and is not particularly limited. The battery case 20 is made of a lightweight metal material with good thermal conductivity, such as aluminum, aluminum alloy, or stainless steel. The battery case 20 in FIG. 2 includes a case body (exterior body) 22 having an opening 22h, and a lid body (sealing plate) 24 that closes the opening 22h. The battery case 20 preferably includes the case body 22 and the lid body 24. The battery case 20 is integrated by joining (for example, welding) the lid body 24 to the periphery of the opening 22h of the case body 22. The battery case 20 is hermetically sealed (sealed).

[0019] The case body 22 has a bottom surface 22d. The lid body 24 faces the bottom surface 22d of the case body 22. The lid body 24 is attached to the case body 22 so as to close the opening 22h of the case body 22. The lid body 24 is substantially rectangular here. Note that in this specification, the term "substantially rectangular" 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.

[0020] As shown in FIG. 1, the positive electrode terminal 30 and the negative electrode terminal 40 protrude to the outside of the battery case 20. Here, the positive electrode terminal 30 and the negative electrode terminal 40 each protrude from the same surface of the battery case 20 (specifically, the lid body 24). However, the positive electrode terminal 30 and the negative electrode terminal 40 may each protrude from different surfaces of the battery case 20. The positive electrode terminal 30 and the negative electrode terminal 40 are disposed at both ends of the lid body 24 in the long side direction Y. The positive electrode terminal 30 and / or the negative electrode terminal 40 are an example of a "terminal for a power storage device". In particular, it is preferable that the negative electrode terminal 40 is a "terminal for a power storage device".

[0021] 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 battery 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 battery case 20. The positive electrode terminal 30 and the negative electrode terminal 40 are each attached to the battery case 20 (specifically, the lid body 24). It is preferable that the positive electrode terminal 30 and the negative electrode terminal 40 are fixed to the battery case 20 (specifically, the lid body 24). The positive electrode terminal 30 and the negative electrode terminal 40 are each insulated from the lid body 24 through a gasket 50 (see FIG. 3) and an insulator 60 (see FIG. 3).

[0022] 3 is a partially enlarged cross-sectional view showing a schematic view of the vicinity of the negative electrode terminal 40. In the following, the terminal structure on the negative electrode terminal 40 side will be described in detail as an example, but the terminal structure on the positive electrode terminal 30 side may be similar. In that case, in the following description, the word "negative electrode" can be appropriately read as "positive electrode".

[0023] As shown in Fig. 3, the lid body 24 is provided with a terminal pull-out hole 24h penetrating in the up-down direction Z. The battery case 20 is preferably provided with the terminal pull-out hole 24h. The terminal pull-out hole 24h is preferably provided in the lid body 24. Although not shown, the terminal pull-out hole 24h is circular (e.g., perfect circle) in plan view. The terminal pull-out hole 24h has an inner diameter large enough to insert a shaft portion 42s of the negative electrode terminal 40 before crimping, which will be described later. The terminal pull-out hole 24h is formed smaller than a flange portion 42f of the negative electrode terminal 40, which will be described later.

[0024] The negative current collecting member 14 is attached to the negative current collecting exposed portion of the negative current collecting member 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 portion 14f that spreads horizontally along the inner surface of the lid 24. The flat plate portion 14f has a hole portion 14h at a position corresponding to the terminal pull-out hole 24h. The hole portion 14h has an inner diameter large enough to insert a shaft portion 42s of the negative terminal 40 before crimping, which will be described later. The negative current collecting member 14 is fixed to the lid 24 together with the negative terminal 40 by crimping in a state insulated via the insulator 60. The negative current collecting member 14 is an example of a "current collecting member".

[0025] The gasket 50 is an insulating member disposed between the upper surface (outer surface) of the lid 24 and the negative electrode terminal 40. An insulating member (e.g., gasket 50) is preferably disposed between the battery case 20 (e.g., lid 24) and the negative electrode terminal 40. The gasket 50 has a function of insulating the lid 24 from the negative electrode terminal 40 and closing the terminal pull-out 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.

[0026] 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 cover body 24 and the shaft portion 42s 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 shaft portion 42s of the negative electrode terminal 40 before the crimping process can be inserted. The tubular portion 51 is inserted into the terminal pull-out hole 24h of the cover body 24. The base portion 52 is a portion that prevents direct contact between the cover body 24 and the 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 in the horizontal direction from the upper end of the tubular portion 51. The base portion 52 is formed, for example, in a circular ring shape so as to surround the terminal pull-out hole 24h of the cover body 24. The base 52 extends along the upper surface of the lid 24. The base 52 is sandwiched between the lower surface 42d of the flange portion 42f of the negative terminal 40 and the upper surface of the lid 24, and is compressed in the vertical direction Z by crimping.

[0027] The insulator 60 is an insulating member disposed between the lower surface (inner surface) of the lid 24 and the negative electrode current collecting member 14. An insulating member (e.g., the insulator 60) is preferably disposed between the battery case 20 (e.g., the lid 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 lid 24. A hole 60h is formed in this flat plate-shaped portion at a position corresponding to the terminal pull-out 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, such as a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA) or polyphenylene sulfide resin (PPS). The flat plate portion of the insulator 60 is sandwiched between the lower surface of the lid 24 and the upper surface of the negative electrode current collecting member 14, and is compressed in the vertical direction Z by crimping.

[0028] <Negative terminal 40> 3, the negative electrode terminal 40 extends from the inside to the outside of the battery case 20 through the terminal pull-out hole 24h. As described below, the negative electrode terminal 40 is configured by integrating two types of conductive members, i.e., a first conductive member 41 and a second conductive member 42, with at least an ultrasonic joint 45. Preferably, the negative electrode terminal 40 is configured by integrating the two types of conductive members with a fastening portion 43 and an ultrasonic joint 45 as in this embodiment.

[0029] As shown in FIG. 3, the negative terminal 40 is inserted into the terminal pull-out hole 24h of the lid 24 and the hole 14h of the negative current collector 14, and the tip end (a cylindrical portion 42p described later) in the insertion direction is crimped onto the negative current collector 14. More specifically, it is crimped to the peripheral portion surrounding the hole 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 lid 24 and electrically connected to the negative current collector 14 by crimping. 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. The crimped portion 40c is preferably welded to the negative current collector 14.

[0030] FIG. 4 is a schematic top view of the negative electrode terminal 40 before being attached to the lid 24 (i.e., before crimping). FIG. 5 is a schematic vertical cross-sectional view of the negative electrode terminal 40 of FIG. 4. As shown in FIG. 5, the negative electrode terminal 40 includes a first conductive member 41, a second conductive member 42, a fastening portion 43, and an ultrasonic joint portion 45. The first conductive member 41 and the second conductive member 42 are electrically connected to each other via two types of connecting portions with different connecting methods, that is, the fastening portion 43 and the ultrasonic joint portion 45. This makes it easier to preferably maintain the first conductive member 41 and the second conductive member 42 in a state where they are in close contact with each other. Therefore, the conduction reliability of the negative electrode terminal 40 can be more preferably improved. However, the fastening portion 43 is not essential and may be omitted in other embodiments.

[0031] The first conductive member 41 is a member disposed outside the battery case 20. The first conductive member 41 is made of a first metal. The first conductive member 41 is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The first conductive member 41 is preferably made of 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 having a lower Vickers hardness (softer) than the second conductive member 42. The first conductive member 41 may be 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).

[0032] As shown in FIG. 4, the first conductive member 41 is circular (for example, perfect circle) in plan view. As shown in FIG. 5, the outer diameter of the first conductive member 41 is larger than a flange portion 42f of the second conductive member 42 described later. The first conductive member 41 has an axis C. The first conductive member 41 has a lower surface (first surface) 41d and an upper surface (second surface) 41u. The lower surface 41d is a surface facing the battery case 20 (specifically, the lid body 24). The lower surface 41d is a surface in contact with the second conductive member 42. The upper surface 41u is a surface opposite to the lower surface 41d in the thickness direction of the first conductive member 41 (direction perpendicular to the lid body 24). The upper surface 41u is a surface away from the battery case 20 and the second conductive member 42. The upper surface 41u is a surface to which an external conductive member 80 (see FIG. 6) described later is connected. Although not particularly limited, the thickness T of the first conductive member 41 (the vertical distance from the upper surface 41u to the lower surface 41d) is preferably 0.5 to 5 mm, and more preferably 1 to 3 mm.

[0033] 5, the first conductive member 41 here has a first recess 41r, a second recess 41c, a thin portion 41t, and a rib 41s. However, in other embodiments, the first conductive member 41 may not have the thin portion 41t and / or the second recess 41c. In addition, the first conductive member 41 here does not have a through hole, but may further have a through hole as described in a second modified example described later.

[0034] As shown in FIG. 5, the first recess 41r is provided on the lower surface (first surface) 41d. The first recess 41r is recessed from the lower surface 41d. The first recess 41r is preferably formed symmetrically with respect to the axis C of the first conductive member 41. Although not shown, the first recess 41r is circular in plan view (including a substantially circular shape with a cutout, for example, a perfect circle). The first recess 41r is formed in a tapered shape that decreases in diameter toward the lower surface 41d of the first conductive member 41 (in other words, as it approaches the second conductive member 42). A part of a flange portion 42f of the second conductive member 42 described later (specifically, a narrowed portion 42n) is inserted into the first recess 41r. The first recess 41r is an example of a "recess on the first surface".

[0035] The second recess 41c is provided on the upper surface (second surface) 41u. The second recess 41c is recessed from the upper surface 41u. The second recess 41c is preferably formed symmetrically with respect to the axis C of the first conductive member 41. As shown in FIG. 4, the second recess 41c is circular (for example, perfect circle) in plan view. Although not particularly limited, as shown in FIG. 5, the outer diameter of the second recess 41c in plan view (diameter in the case of a perfect circle, the shortest length passing through the center in the case of a non-perfect circle) is smaller than the outer diameter of the first recess 41r.

[0036] As shown in FIG. 4, the thin-walled portion 41t is circular (for example, perfect circle) in plan view. As shown in FIG. 5, the thin-walled portion 41t is formed to be thinner than its outer peripheral portion. The thickness T2 of the thin-walled portion 41t is smaller than the thickness T of the first conductive member 41. The thin-walled portion 41t is a region where the first recess 41r and the second recess 41c overlap in plan view. The thin-walled portion 41t is preferably provided by forming the second recess 41c on the surface (i.e., the upper surface 41u) opposite to the lower surface 41d on which the first recess 41r is formed as in this embodiment. The thin-walled portion 41t is provided with an ultrasonic bonding portion 45. This reduces the energy required during bonding, and improves weldability. In addition, the distortion and deformation of the first conductive member 41 can be suppressed to a small extent during ultrasonic bonding.

[0037] The first conductive member 41 has a first region A1 and a second region A2, which are regions divided in the radial direction above the first recess 41r. The first region A1 is a region that overlaps with the cylindrical portion 42p of the second conductive member 42 described later in the direction in which the cylindrical portion 42p extends (the vertical direction Z in FIG. 5). The first region A1 is a region that overlaps with the cylindrical portion 42p in a plan view. In other words, it is a region directly above the cylindrical portion 42p. The first region A1 is ring-shaped (e.g., annular) here. In the first region A1, a first upper surface S1 on the opposite side to the lower surface 41d protrudes in a direction away from the lower surface 41d (or the second conductive member 42) (upward in FIG. 5) beyond the second upper surface S2 of the second region A2. The thickness T1 of the first region A1 is smaller than the thickness T of the first conductive member 41 by, for example, the amount of the first recess 41r (i.e., T1 <T)。

[0038] The second region A2 is located radially inwardly of the first region A1, and is a region where the ultrasonic bonded portion 45 is formed. The second region A2 is the thin-walled portion 41t here. The second region A2 is wider in the radial direction (long side direction Y in FIG. 4) than the first region A1. In the second region A2, the second upper surface S2 (bottom surface of the second recess 41c) opposite to the lower surface 41d is located lower than the first upper surface S1 of the first region A1 by the amount of the second recess 41c. It is preferable that the second region A2 does not protrude toward the upper surface 41u side (upward in FIG. 4) than the first region A1. This requires less energy during bonding, and makes it easier to stably form the ultrasonic bonded portion 45 in the second region A2. In addition, distortion and deformation of the first conductive member 41 can be suppressed to a small amount during ultrasonic bonding.

[0039] The thickness T2 of the second region A2 is here smaller than the thickness T1 of the first region A1 by the amount of the second recess 41c (i.e., T2 < T1 < T). The thickness T1 of the first region A1 and the thickness T2 of the second region A2 preferably satisfy T1 / T2 ≤ 0.5, and more preferably satisfy T1 / T2 < 0.5. Thereby, the ultrasonic joint 45 can be formed more stably in the second region A2. Further, when the thickness T2 of the second region A2 is small, the second region A2 is likely to be deformed or the ultrasonic joint 45 is likely to be damaged, and thus applying the technology disclosed herein has a particularly high effect. However, as also described in the second modification example to be described later, the first upper surface S1 of the first region A1 and the second upper surface S2 of the second region A2 may be at the same or substantially the same height.

[0040] The rib 41s protrudes from the upper surface (second surface) 41u. The rib 41s is provided on the outer peripheral side of the ultrasonic joint 45. The rib 41s is provided on the inner peripheral side of the fastening portion 43. The rib 41s is provided between the first region A1 and the second region A2 in the radial direction. By providing the rib 41s between the first region A1 and the second region A2, it is possible to suppress the second region A2 from being deformed or the ultrasonic joint 45 from being damaged in the manufacturing process to be described later (for example, caulking of the terminal to the current collector, etc.). Therefore, the reliability of the connection portion between the first conductive member 41 and the second conductive member 42 can be improved. The rib 41s may be provided at a position away from the outer peripheral edge of the second recess 41c to the outside.

[0041] The rib 41s is preferably formed symmetrically with respect to the axis C of the first conductive member 41. The rib 41s is ring-shaped (for example, annular). The rib 41s is preferably provided annularly so as to surround the second region A2. A part of the rib 41s may be disposed in the first region A1. The ratio of the formation area of ​​the rib 41s to the area of ​​the first region A1 is preferably less than 0.5, more preferably less than 0.3. Although the details will be described later, when a plurality of energy storage devices 100 are electrically connected to each other to fabricate an energy storage module 200 (see FIG. 7), an external conductive member 80 (see FIG. 6) may be attached to the rib 41s. For example, the external conductive member 80 may be metal-joined (for example, welded) to the rib 41s.

[0042] The second conductive member 42 is a member that extends from the inside to the outside of the battery case 20 through the terminal pull-out hole 24h. The second conductive member 42 is made of a second metal different from the first metal. The second conductive member 42 is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The second conductive member 42 is preferably made of copper or a copper alloy. The second conductive member 42 is made of copper here. 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 conductive member 42 may be made of the same metal as the negative electrode current collecting member 14, or an alloy that has the same metal element as the first component. The second conductive member 42 may have a metal coating portion in which a metal such as Ni is coated on a part or all of the surface.

[0043] As shown in FIG. 5, the second conductive member 42 has an axis C. The axis C of the second conductive member 42 coincides with the axis C of the first conductive member 41. Here, the second conductive member 42 has a flange portion 42f electrically connected to the first conductive member 41, a shaft portion 42s connected to the lower end of the flange portion 42f, and a cylindrical portion 42p located at the end (lower end) of the shaft portion 42s opposite to the side where the flange portion 42f is located. The second conductive member 42 preferably has the flange portion 42f and the shaft portion 42s connected to one surface of the flange portion 42f. The second conductive member 42 has a portion disposed in the first recess 41r of the first conductive member 41. It is preferable that at least a part of the flange portion 42f of the second conductive member 42 is disposed in the first recess 41r of the first conductive member 41.

[0044] The flange portion 42f has a larger outer shape than the shaft portion 42s. The flange portion 42f is a portion that protrudes from the terminal pull-out hole 24h of the lid body 24 to the outside of the battery case 20. As shown in FIG. 3, the flange portion 42f has a larger outer shape than the terminal pull-out hole 24h of the lid body 24. The outer shape of the flange portion 42f here is substantially cylindrical. The flange portion 42f is preferably circular (for example, perfect circle) in a plan view. The axis of the flange portion 42f coincides with the axis C of the second conductive member 42. In this embodiment, the flange portion 42f has a lower surface 42d, a side surface (outer peripheral surface) 42o extending upward from the lower surface 42d, and a constricted portion 42n in which a part of the side surface 42o is constricted.

[0045] The constricted portion 42n is provided continuously or intermittently on a part of the side surface 42o of the flange portion 42f. The constricted portion 42n is preferably mechanically fastened to the first conductive member 41 (for example, to the inner surface of the first recess 41r). Although not shown, the constricted portion 42n is ring-shaped (for example, annular) in a plan view. The constricted portion 42n is formed symmetrically with respect to the axis C of the flange portion 42f. The constricted portion 42n is formed in an inverted tapered shape that expands in diameter toward the upper surface 41u (in other words, as it moves away from the shaft portion 42s). The constricted portion 42n is inserted into the first recess 41r of the first conductive member 41. The constricted portion 42n is fitted into the first recess 41r of the first conductive member 41 and is fitted into the first recess 41r. The constricted portion 42n is an example of a "portion disposed in a recess".

[0046] As shown in FIG. 5, the shaft portion 42s extends downward from the lower end of the flange portion 42f. As shown in FIG. 3, when the negative electrode terminal 40 is attached to the cover body 24, the shaft portion 42s is preferably inserted into the terminal lead-out hole 24h of the cover body 24. Although not shown, the shaft portion 42s has a cylindrical outer shape here. The axis of the shaft portion 42s coincides with the axis C of the second conductive member 42. Before the crimping process, the lower end of the shaft portion 42s, i.e., the end opposite to the side where the flange portion 42f is located, is hollow. The lower end of the shaft portion 42s forms the cylindrical portion 42p.

[0047] The cylindrical portion 42p here has a hollow cylindrical shape. The cylindrical portion 42p extends along the up-down direction Z. The cylindrical portion 42p is disposed outside the first recess 41r. When the negative electrode terminal 40 is attached to the lid 24, the cylindrical portion 42p is expanded by crimping, and is a portion that constitutes the crimped portion 40c. It is preferable that the cylindrical portion 42p is electrically connected to the negative electrode current collecting member 14 inside the battery case 20 by crimping.

[0048] The fastening portion 43 is a connecting portion where the first conductive member 41 and the second conductive member 42 are mechanically fastened. By having the fastening portion 43, the connection state between the first conductive member 41 and the second conductive member 42 is more likely to be stable. The fastening portion 43 is provided on the outer periphery side of the ultrasonic joint portion 45. The fastening portion 43 is provided on the outer periphery side of the cylindrical portion 42p. The fastening portion 43 is provided on the outer periphery side of the rib 41s. Here, the fastening portion 43 is formed continuously. Here, the fastening portion 43 is ring-shaped (for example, annular) in a plan view. This increases the strength of the fastening portion 43, and improves the conduction reliability of the negative electrode terminal 40.

[0049] The fastening portion 43 is configured here by a part of the inner wall of the first recess 41r of the first conductive member 41 entering the narrowed portion 42n of the second conductive member 42. As a result, the inner wall of the first recess 41r of the first conductive member 41 is fixed (for example, pressed and fixed) to the narrowed portion 42n of the second conductive member 42. It is preferable that the fastening portion 43 is configured by fastening the inner wall of the first recess 41r of the first conductive member 41 and the side surface 42o of the flange portion 42f of the second conductive member 42. This can improve the strength of the fastening portion 43.

[0050] The method of forming the fastening portion 43 is not particularly limited as long as it is a mechanical joint using mechanical energy, and may be, for example, press-fitting, shrink-fitting, caulking, riveting, folding, bolt-jointing, or the like. In some preferred embodiments, the fastening portion 43 is preferably a fitting portion in which the first recess 41r of the first conductive member 41 and the constricted portion 42n of the second conductive member 42 are fitted together. The fastening portion 43 may be, for example, a press-fit fitting portion in which the constricted portion 42n of the second conductive member 42 is fitted into the first recess 41r of the first conductive member 41 by press-fitting (self-clinching). This allows the first conductive member 41 and the second conductive member 42 to be suitably fixed together.

[0051] The ultrasonic joint 45 is a metal joint formed by ultrasonically joining the first conductive member 41 and the second conductive member 42. The ultrasonic joint 45 is provided in the second region A2. The ultrasonic joint 45 is provided on the inner periphery side of the rib 41s. The ultrasonic joint 45 is provided on the inner periphery side of the cylindrical portion 42p. The ultrasonic joint 45 is provided in the thin-walled portion 41t here. The ultrasonic joint 45 is provided at a position spaced apart from the fastening portion 43 here. The ultrasonic joint 45 is provided on the inner periphery side (center side) of the fastening portion 43. The ultrasonic joint 45 may be a joint having a relatively low strength (fragile) compared to the fastening portion 43. By disposing such an ultrasonic joint 45 on the inner periphery side of the fastening portion 43, the ultrasonic joint 45 can be stably maintained and the conduction reliability of the negative electrode terminal 40 can be improved over a long period of time. The ultrasonic bonding portion 45 can be clearly distinguished from, for example, laser welding by the pressure marks of a horn used in the ultrasonic bonding process described later.

[0052] The ultrasonic joint 45 is formed continuously or intermittently in plan view. The ultrasonic joint 45 is preferably formed symmetrically with respect to the axis C of the first conductive member 41 and the second conductive member 42 (for example, the flange portion 42f). In some preferred embodiments, the ultrasonic joint 45 is circular (for example, perfect circle) in plan view, as shown in FIG. 4. This increases the strength of the ultrasonic joint 45 and improves the conduction reliability of the negative electrode terminal 40. In addition, the area of ​​the ultrasonic joint 45 is increased, making it possible to reduce the conduction resistance and reduce the resistance. Furthermore, it is possible to suppress resistance heat generation to a low level, thereby reducing the thermal effect on a resin member such as the gasket 50.

[0053] In some preferred embodiments, the negative terminal 40 further includes an external conductive member 80 (see FIG. 6). FIG. 6 is a vertical cross-sectional view showing a schematic connection between the negative terminal 40 and the external conductive member 80. As shown in FIG. 6, the external conductive member 80 is attached to a rib 41s of the first conductive member 41 here. More specifically, the external conductive member 80 is metal-joined (for example, welded) to the rib 41s. The external conductive member 80 is preferably made of the same metal as the first conductive member 41, or an alloy having the same metal element as the first component. The external conductive member 80 is preferably made of the first metal constituting the first conductive member 41. The external conductive member 80 is preferably made of aluminum or an aluminum alloy. The external conductive member 80 is made of aluminum here. The external conductive member 80 is preferably plate-shaped (more specifically, flat-shaped).

[0054] 7, the external conductive member 80 has a generally rectangular shape having short sides and long sides in a plan view. The external conductive member 80 is disposed such that the long side of the rectangle is aligned with the long side direction Y of the lid body 24. It is preferable that the external conductive member 80 extends along the long side direction Y of the lid body 24 as in this embodiment.

[0055] As shown in FIG. 6, the external conductive member 80 is a region divided into two in the long side direction Y, and has a connection portion 80a electrically connected to the rib 41s, and an extension portion 80b extending from the connection portion 80a to one side in the long side direction Y (to the left in FIG. 6).

[0056] In the connection portion 80a, a welded joint 82 is provided on the outer periphery of the rib 41s. The welded joint 82 is formed continuously or intermittently in a plan view. Here, the welded joint 82 is provided continuously. The welded joint 82 is circular (for example, perfect circle). The welded joint 82 is preferably a laser welded part. According to the study by the present inventors, if the metal joint between the external conductive member 80 and the first conductive member 41 reaches the second conductive member 42, the metal joint may become brittle. By metal-joining the external conductive member 80 to the rib 41s, it is possible to prevent the metal joint between the external conductive member 80 and the first conductive member 41 from reaching the second conductive member 42, and to prevent a decrease in reliability of the joint. Therefore, it is possible to improve the conduction reliability of the energy storage module 200. However, the external conductive member 80 does not necessarily need to be attached to the rib 41s, and in other embodiments, it may be attached to a place other than the rib 41s.

[0057] The extension portion 80b is a portion to which a bus bar 90 (see FIG. 7) is attached when a plurality of energy storage devices 100 are electrically connected to one another to fabricate an energy storage module 200 (see FIG. 7). The provision of the extension portion 80b makes it possible to ensure a sufficient ground contact area with the bus bar 90, thereby improving the electrical conductivity reliability of the energy storage module 200. However, in other embodiments, the bus bar 90 may be directly connected to the first conductive member 41 (for example, the upper surface 41u or the rib 41s) without going through the external conductive member 80 (or the extension portion 80b).

[0058] <Method of Manufacturing Negative Electrode Terminal 40> The negative electrode terminal 40 as described above can be suitably manufactured by a manufacturing method including, for example, a fastening step of preparing the first conductive member 41 and the second conductive member 42, mechanically fastening the first conductive member 41 and the second conductive member 42, and an ultrasonic bonding step of ultrasonically bonding the first conductive member 41 and the second conductive member 42, in this order. By performing the bonding step after the fastening step, it is possible to prevent the ultrasonic bonded portion 45 from being damaged in the fastening step, and it is possible to form the ultrasonic bonded portion 45 with a stable shape with high accuracy. However, the order of the fastening step and the bonding step may be reversed, or they may be performed approximately simultaneously. In addition, the manufacturing method disclosed herein may further include other steps at any stage.

[0059] In the fastening step, the first conductive member 41 and the flange portion 42f of the second conductive member 42 are mechanically fastened to form the fastening portion 43. The fastening portion 43 can be formed, for example, by arranging the constricted portion 42n of the second conductive member 42 in the first recess 41r of the first conductive member 41, and by deforming the first recess 41r of the first conductive member 41 along the outer shape of the constricted portion 42n of the second conductive member 42, thereby fixing the inner wall of the first recess 41r with the second conductive member 42. This can improve the strength of the fastening portion 43. In some preferred embodiments, the fastening portion 43 is formed by fitting (self-clinching) the first recess 41r of the first conductive member 41 and the constricted portion 42n of the second conductive member 42. For example, the fastening portion 43 can be formed by horizontally press-fitting the constricted portion 42n of the second conductive member 42 into the first recess 41r of the first conductive member 41. This can improve the workability of the fastening step.

[0060] In the ultrasonic bonding process, the second conductive member 42 is ultrasonically bonded to the second region A2 of the first conductive member 41 in a state where a part of the second conductive member 42 (for example, the flange portion 42f) is disposed in the first recess 41r of the first conductive member 41, to form an ultrasonic bonded portion 45. The ultrasonic bonded portion 45 is formed by ultrasonically bonding the second conductive member 42 to the thin portion 41t. In ultrasonic bonding, for example, a horn is pressed against the second region A2 (specifically, the thin portion 41t) of the first conductive member 41, and ultrasonic vibration is applied while applying a pressing load. Note that the method and conditions of ultrasonic bonding may be the same as those of the conventional method. In ultrasonic bonding, brittle intermetallic compounds are less likely to be generated at the bonding interface between the first conductive member 41 and the second conductive member 42 compared to, for example, laser welding. Therefore, a high-strength metal bonded portion can be stably formed. In addition, in this embodiment, since the second region A2 is configured with the thin-walled portion 41t, even if the first conductive member 41 is deformed in this process, the flow of material can be suitably guided to the rib 41s. Therefore, even if the first conductive member 41 does not have a through hole, for example, it is possible to suppress unintended distortion or deformation of the first conductive member 41.

[0061] <Method of Manufacturing Electricity Storage Device 100> The electricity storage device 100 is characterized by using the positive electrode terminal 30 and / or the negative electrode terminal 40 as described above, and other manufacturing processes may be similar to those of the conventional method. The electricity storage device 100 can be manufactured, for example, by preparing the electrode body 10, the electrolyte, the case main body 22, the lid body 24, the positive electrode terminal 30, and the negative electrode terminal 40 as described above, and by a manufacturing method including, in this order, a terminal attachment step and a case joining step.

[0062] In the terminal attachment step, the positive terminal 30, the positive current collecting member 13, the negative terminal 40, and the negative current collecting member 14 are attached to the lid 24 and integrated. The negative terminal 40 and the negative current collecting member 14 are fixed to the lid 24 by crimping (riveting), for example, as shown in FIG. 3. In some preferred embodiments, this step includes an insertion step and a crimping step in this order. In addition, other steps may be included at any stage. For example, after the crimping step, an external conductive member attachment step, which will be described later, may be included.

[0063] In the insertion step, a part of the second conductive member 42 of the negative terminal 40 is inserted into the hole 14h of the negative current collecting member 14. More specifically, the shaft portion 42s before crimping is passed through the cylindrical portion 51 of the gasket 50, the terminal lead-out hole 24h of the lid body 24, the hole 60h of the insulator 60, and the hole 14h of the negative current collecting member 14, in that order, from above the lid body 24. This causes the cylindrical portion 42p of the negative terminal 40 to protrude downward from the hole 14h of the negative current collecting member 14.

[0064] In the crimping process, the second conductive member 42 of the negative terminal 40 is crimped onto the negative current collecting member 14. More specifically, the cylindrical portion 42p protruding from the hole 14h of the negative current collecting member 14 is crimped onto the negative current collecting member 14 so that a compressive force is applied in the vertical direction Z. The crimping process is performed here with a gasket 50 sandwiched between the negative terminal 40 and the lid 24, and an insulator 60 sandwiched between the lid 24 and the negative current collecting member 14. As a result, a crimped portion 40c is formed at the tip end (the lower end in FIG. 3) of the shaft portion 42s of the negative terminal 40.

[0065] FIG. 8 is a vertical cross-sectional view showing an example of this step. In FIG. 8, the lid 24, the gasket 50, the insulator 60, and the negative electrode current collecting member 14 are omitted. In some preferred embodiments, a crimping device including a punch (press jig) 91 and a die (receiving jig) 92 is first prepared as shown in FIG. 8. The die 92 has a hollow cylindrical shape here, and has a hollow part in the center whose inner diameter is larger than the outer diameter of the rib 41s of the first conductive member 41. Although not particularly limited, in this embodiment, the inner diameter of the die 92 is Φ=8.2 mm, and the outer diameter is Φ=15 mm or more. Next, the negative electrode terminal 40 is placed on the top surface of the die 92 in a state of being upside down. As a result, the upper surface 41u of the first conductive member 41, specifically, the outer peripheral side of the rib 41s, faces the die 92. The upper surface 41u is in contact with the die 92 on the outer peripheral side of the rib 41s.

[0066] In this embodiment, the first conductive member 41 has a second recess 41c on the upper surface 41u. The first region A1 of the first conductive member 41 protrudes toward the upper surface 41u side more than the second region A2. In other words, the first upper surface S1 of the first region A1 (the surface opposite to the surface on the side on which the first recess 41r is formed) of the first conductive member 41 protrudes in a direction away from the lower surface 41d (downward in FIG. 8) more than the second upper surface S2 of the second region A2 (the surface opposite to the surface on which the first recess 41r is formed). At least a part of the first upper surface S1 of the first region A1 (here, more than half of the second upper surface S2) abuts against the die 92. On the other hand, the second upper surface S2 of the second region A2 on which the ultrasonic bonding portion 45 is formed is floating from the die 92. The second conductive member 42 does not abut against the die 92. This makes it possible to more effectively prevent the ultrasonic bonding portion 45 from being damaged.

[0067] Next, the tip of the punch 91 is inserted into the cylindrical portion 42p (hollow portion) of the second conductive member 42 while the outer periphery side of the rib 41s, more specifically, at least a part of the first upper surface S1 of the first region A1 is in contact with the die 92. Then, as shown by the arrows in FIG. 8, a compressive force is applied in the direction in which the cylindrical portion 42p extends (the direction in which the axis C extends, here the vertical direction Z), so that the cylindrical portion 42p is pushed outward and deformed by the tip of the punch 91. As a result, the cylindrical portion 42p is plastically deformed so as to embrace the outer edge portion. As a result, the crimped portion 40c is formed on the negative electrode current collecting member 14, and each part is crimped and fixed.

[0068] In this embodiment, the first conductive member 41 has a rib 41s between the first region A1 and the second region A2. This effectively prevents the second region A2 from being deformed and the ultrasonic joint 45 provided in the second region A2 from being damaged in this process. Therefore, the connection between the first conductive member 41 and the second conductive member 42 becomes a highly reliable terminal. In this embodiment, the first conductive member 41 does not have a through hole, so that the area of ​​the ultrasonic joint 45 can be increased, the conduction resistance can be reduced, and the resistance can be reduced. Furthermore, the resistive heat can be kept low, and the thermal effect on a resin member such as the gasket 50 can be reduced.

[0069] In addition, in this embodiment, the first region A1 protrudes toward the upper surface 41u side more than the second region A2. This allows the die 92 to receive the area directly below the cylindrical portion 42p, making it easier to crimp the cylindrical portion 42p. Furthermore, since the second region A2 is recessed toward the lower surface 41d side more than the first region A1 (is located higher), the compressive force of the crimping process is less likely to be applied to the area where the ultrasonic joint 45 is formed. Therefore, the load on the second region A2 or the ultrasonic joint 45 provided in the second region A2 can be reduced to a higher level, and damage to the ultrasonic joint 45 can be more effectively suppressed.

[0070] By the above-mentioned crimping process, the base 52 of the gasket 50 and the flat portion of the insulator 60 are compressed, and the gasket 50, the lid 24, the insulator 60, and the negative current collector 14 are integrally fixed to the lid 24, and the terminal lead-out hole 24h is sealed. The negative current collector 14 is welded to the negative current collector exposed portion of the negative current collector 12, and the negative electrode of the electrode body 10 and the negative electrode terminal 40 are electrically connected. The mounting method of the positive electrode terminal 30 and the positive current collector 13 may be the same as that of the negative electrode terminal 40 and the negative current collector 14 described above. The positive current collector 13 is welded to the positive current collector exposed portion of the positive current collector 11, and the positive electrode of the electrode body 10 and the positive electrode terminal 30 are electrically connected. As a result, the lid 24, the positive electrode terminal 30, the negative electrode terminal 40, and the electrode body 10 are integrated together.

[0071] In some embodiments, the method includes an external conductive member attachment step of attaching (e.g., welding) the external conductive member 80 to the negative terminal 40 after the crimping step. The welding of the external conductive member 80 is preferably performed after the crimping step. In this step, the external conductive member 80 is welded (e.g., laser welded) to the annular rib 41s. As a result, a welded joint 82 is formed, for example, on the peripheral portion of the rib 41s of the first conductive member 41, and the external conductive member 80 is attached to the negative terminal 40.

[0072] In the case joining process, the electrode body 10 integrated with the lid body 24 is accommodated in the internal space of the case body 22, and the lid body 24 is welded to the periphery of the opening 22h of the case body 22. The welding can be performed by a conventionally known method (e.g., laser welding). As a result, the opening 22h of the case body 22 is sealed, and the case body 22 and the lid body 24 are integrated. Thereafter, a nonaqueous electrolyte is injected through a liquid injection port (not shown), and the liquid injection port is closed to hermetically seal the electricity storage device 100. In this manner, the electricity storage device 100 can be manufactured.

[0073] <Uses of the Power Storage Device 100> The power storage device 100 can be used for various purposes, and can be suitably used as a power source (driving power source) for motors mounted on various vehicles, such as passenger cars and trucks. The type of vehicle is not particularly limited, and examples thereof include a plug-in hybrid electric vehicle (PHEV), a hybrid electric vehicle (HEV), and a battery electric vehicle (BEV). The power storage device 100 can also be suitably used as a power storage module 200 in which a plurality of power storage devices 100 are electrically connected to each other via a bus bar 90 (see FIG. 7).

[0074] FIG. 7 is a perspective view that shows a schematic diagram of a power storage module 200 according to an embodiment. As shown in FIG. 7, the power storage module 200 includes a plurality of power storage devices 100 and a bus bar 90 that electrically connects the first power storage device 100 and the second power storage device 100 to each other. The bus bar 90 is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The bus bar 90 has a flat plate shape, and here, the bus bar 90 is bridged between the positive terminal 30 of the first power storage device 100 and the negative terminal 40 of the second power storage device 100 via an extension portion 80b of the external conductive member 80. The bus bar 90 is preferably welded (for example, laser welded) to the external conductive member 80.

[0075] Although several embodiments of the present invention have been described above, the above embodiments are merely examples. The present invention can be implemented in various other forms. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the field. The technology described in the claims includes various modifications and changes to the above-exemplified embodiments. For example, it is possible to replace a part of the above-mentioned embodiment with another modified form, and it is also possible to add another modified form to the above-mentioned embodiment. Furthermore, if a technical feature is not described as essential, it is also possible to delete it as appropriate.

[0076] (1) For example, in FIG. 4 of the above embodiment, the first conductive member 41 has a circular shape in a plan view. However, this is not limited to this. The first conductive member 41 may have a rectangular shape having long sides and short sides, and may have, for example, an extension portion, as described in Patent Document 1, for example. In this case, when constructing the energy storage module 200, the bus bar 90 may be directly connected to the extension portion of the first conductive member 41 without using the external conductive member 80.

[0077] (2) For example, in the embodiment described above in Fig. 5, the constricted portion 42n is provided in a part of the side surface 42o of the second conductive member 42. However, this is not limited to this. The constricted portion 42n may be provided, for example, in a portion other than the side surface 42o.

[0078] FIG. 9 is a view corresponding to FIG. 5 according to the first modification. As shown in FIG. 9, the negative electrode terminal 140 according to this modification includes a first conductive member 141, a second conductive member 142, a fastening portion 143, and an ultrasonic joint portion 45. The first conductive member 141 may be similar to the first conductive member 41 except that the first conductive member 141 does not have the thin portion 41t and the second recess 41c and is formed thinner overall than that shown in FIG. 5. The second conductive member 142 may be similar to the second conductive member 42 except that the second conductive member 142 has a constricted portion 142n on the upper surface 142u of the flange portion 142f and the flange portion 142f is formed thicker than that shown in FIG. The fastening portion 143 is a fitting portion in which the first recess 41r of the first conductive member 141 and the constricted portion 142n provided on the upper surface 142u of the second conductive member 42 are fitted together.

[0079] In this modification, the outer diameter R1 of the first conductive member 141 and the outer diameter R2 of the flange portion 142f of the second conductive member 142 are substantially the same. According to this modification, the proportion of the second conductive member 142 in the region overlapping with the tubular portion 42p (the region compressed in the crimping process) is increased, and therefore, particularly when the Vickers hardness of the second conductive member 142 is greater than that of the first conductive member 141, the load on the second region A2 to the ultrasonic joint 45 provided in the second region A2 can be reduced to a higher level, and damage to the ultrasonic joint 45 can be more effectively prevented.

[0080] (3) For example, in FIG. 5 of the embodiment described above, the first conductive member 41 does not have a through hole 41h, and the ultrasonic bonding portion 45 is provided in a circular shape in a plan view. Also, the first upper surface S1 of the first region A1 protrudes in the thickness direction beyond the second upper surface S2 of the second region A2. However, this is not limited to this. The first conductive member 41 may have a through hole 41h, and the ultrasonic bonding portion 45 may be annular or the like in a plan view. The first upper surface S1 of the first region A1 and the second upper surface S2 of the second region A2 may be at the same or approximately the same height.

[0081] 10 is a view corresponding to FIG. 5 according to the second modified example. As shown in FIG. 10, a negative electrode terminal 240 according to this modified example includes a first conductive member 241, a second conductive member 242, a fastening portion 43, and an ultrasonic joint portion 245. The first conductive member 241 may be similar to the first conductive member 41, except that it has a through hole 241h and is formed to be thinner overall than that of FIG. 5. The second conductive member 242 may be similar to the second conductive member 42, except that a flange portion 242f is formed to be thicker than that of FIG. 5.

[0082] The through-hole 241h penetrates the first conductive member 241 in the vertical direction Z. The through-hole 241h is provided on the inner peripheral side (center side) of the fastening portion 43 and the ultrasonic bonding portion 245. The through-hole 241h is provided at the center of the second region A2. The through-hole 41h is circular (for example, a perfect circle) in plan view here. Although not particularly limited, the outer diameter of the through-hole 41h (the diameter in the case of a perfect circle, and the shortest length passing through the center in the case of a non-perfect circle) is preferably, for example, 5 to 7 mm.

[0083] The ultrasonic bonding portion 245 is continuously formed along the circumferential direction of the through-hole 41h here. The ultrasonic bonding portion 245 is provided around the through-hole 41h. The ultrasonic bonding portion 45 is provided at a position away from the through-hole 41h here. The ultrasonic bonding portion 245 is ring-shaped (for example, an annular shape) in plan view. However, the ultrasonic bonding portion 245 may be composed of a plurality of parts, and the plurality of parts may be arranged at spaced positions respectively.

[0084] In this modification, the first upper surface S1 of the first region A1 and the second upper surface S2 of the second region A2 are at the same or substantially the same height. The thickness T1 of the first region A1 and the thickness T2 of the second region A2 are substantially the same thickness (T1 ≒ T2). The thickness T1 of the first region A1 and the thickness T2 of the second region A2 preferably satisfy the following relationship: 0.8 ≦ T1 / T2 ≦ 1.2; and more preferably satisfy the following relationship: 0.8 < T1 / T2 < 1.2;. Since the rib 41s is provided between the first region A1 and the second region A2, even if T1 and T2 are substantially the same thickness, during the caulking process, the load on the second region A2 or the ultrasonic bonding portion 45 provided in the second region A2 can be reduced to a higher level, and the ultrasonic bonding portion 45 can be effectively prevented from being damaged. This modification is particularly preferable when the thickness T1 of the first region A1 is thin (for example, when T1 is 1.5 mm or less, and further when T1 is 0.8 mm or less). The thickness T1 of the first region A1 is preferably 0.1 mm or more. The thickness T2 of the second region A2 is preferably, for example, 2.0 mm or less, and more preferably 0.6 mm or less. The thickness T2 of the second region A2 is preferably 0.1 mm or more.

[0085] In this modification, it is preferable that the thickness (maximum thickness) T3 of the flange portion 42f and the thickness T1 of the first region A1 satisfy 3≦T3 / T1. By making the thickness of the flange portion 42f larger than the thickness T1 of the first region A1, it is possible to prevent unintended deformation when the tubular portion 42p described below is crimped. In addition, it is possible to prevent a load from being applied to the ultrasonic joint 45.

[0086] (4) For example, in the above embodiment, the negative terminal 40 is fixed onto the negative current collecting member 14 by deforming and crimping the cylindrical portion 42p of the negative terminal 40, and the negative terminal 40 and the negative current collecting member 14 are electrically connected. However, this is not limited to this. The method for electrically connecting the negative current collecting member 14 and the negative terminal 40 may be, for example, a mechanical fixation other than crimping, metal joining such as welding, or a combination thereof.

[0087] As described above, specific aspects of the technology disclosed herein include those described in the following sections. Item 1: A terminal for an energy storage device comprising: a first conductive member made of a first metal and having a recess on a first surface; a second conductive member made of a second metal different from the first metal and having a portion disposed within the recess; and an ultrasonic joint at which the first conductive member and the second conductive member are ultrasonically joined, wherein the first conductive member is disposed outer circumferentially of the ultrasonic joint and has a rib protruding from a second surface of the first conductive member opposite the first surface. Item 2: The terminal described in Item 1, wherein the second conductive member has a hollow tubular portion, and when a region of the first conductive member that overlaps with the tubular portion in the direction in which the tubular portion extends is defined as a first region, and a region that is located more inward than the first region and in which the ultrasonic bonding portion is formed is defined as a second region, the rib is provided between the first region and the second region. Item 3: The terminal according to item 2, wherein the second region does not protrude further toward the second surface than the first region. Item 4: The terminal according to item 2 or 3, wherein the thickness T1 of the first region and the thickness T2 of the second region satisfy the following relationship: 0.8≦T1 / T2≦1.2. Item 5: The terminal according to any one of items 2 to 4, wherein the second conductive member is made of copper or a copper alloy and has a flange portion, at least a portion of the flange portion is disposed within the recess of the first conductive member, and a thickness T3 of the flange portion and a thickness T1 of the first region satisfy the following relationship: 3≦T3 / T1. Item 6: The terminal according to item 2 or 3, wherein the thickness T1 of the first region and the thickness T2 of the second region satisfy the following relationship: T1 / T2≦0.5. Item 7: The terminal according to any one of items 1 to 6, further comprising a fastening portion at an outer circumferential side of the ultrasonic joint portion, where the first conductive member and the second conductive member are mechanically fastened to each other. Item 8: The terminal according to any one of items 1 to 7, further comprising an external conductive member welded to the rib of the first conductive member. Item 9: An electrode assembly having a first electrode and a second electrode having a polarity different from that of the first electrode, a battery case that houses the electrode assembly, a terminal that is electrically connected to the first electrode and attached to the battery case, and a current collecting member that has a hole and electrically connects the first electrode and the terminal inside the battery case, wherein the terminal comprises a first conductive member made of a first metal and having a recess on a first surface, a second conductive member made of a second metal different from the first metal and having a portion disposed within the recess, and a current collecting member that is electrically connected to the first conductive member and the second conductive member. and an ultrasonic bonding portion at which a first conductive member and a second conductive member are ultrasonically bonded to each other, the first conductive member being disposed outer circumferentially of the ultrasonic bonding portion and having a rib protruding from a second surface of the first conductive member opposite the first surface, the method comprising: an insertion step of inserting a portion of the second conductive member of the terminal into the hole of the current collecting member; and a crimping step of crimping the portion of the second conductive member onto the current collecting member with a receiving jig abutted against the outer circumferential side of the rib of the terminal after the insertion step. Item 10: The manufacturing method according to item 9, wherein in the inserting step, the terminal has the ultrasonic joint between the first conductive member and the second conductive member. Item 11: A manufacturing method according to item 9 or 10, wherein the second conductive member of the terminal has a hollow tubular portion, and when a region of the first conductive member that overlaps with the tubular portion in the direction in which the tubular portion extends is defined as a first region, and a region that is located more inward than the first region and in which the ultrasonic bonding portion is formed is defined as a second region, the second region does not protrude toward the second surface side beyond the first region, and in the crimping process, the tubular portion of the second conductive member is crimped onto the current collecting member with a receiving jig abutted against the second surface side of the first region. Item 12: The manufacturing method according to item 11, wherein the terminal has a thickness T1 of the first region and a thickness T2 of the second region that satisfy the following relationship: 0.8≦T1 / T2≦1.2. Item 13: The manufacturing method according to item 11 or 12, wherein the second conductive member of the terminal is made of copper or a copper alloy and has a flange portion, at least a portion of the flange portion is disposed within the recess of the first conductive member, and a thickness T3 of the flange portion and a thickness T1 of the first region satisfy the following relationship: 3≦T3 / T1. Item 14: The manufacturing method according to item 11, wherein the terminal has a thickness T1 of the first region and a thickness T2 of the second region that satisfy the following relationship: T1 / T2≦0.5. Item 15: The manufacturing method according to any one of items 9 to 14, wherein the terminal further includes a fastening portion in which the first conductive member and the second conductive member are mechanically fastened to each other on the outer peripheral side of the ultrasonic joint portion. Item 16: The manufacturing method according to any one of items 9 to 15, wherein the terminal further includes an external conductive member, and further includes an external conductive member attachment step of welding and joining the external conductive member to the rib after the crimping step. [Explanation of symbols]

[0088] 10 Electrode body 14 Negative electrode current collector (current collector) 20 Battery case 24 Lid 40, 140, 240 Negative terminal (terminal) 40c Crimping part 41, 141, 241 First conductive member 41d Bottom surface (first surface) 41r 1st recess 41t Thin wall part 41s Rib 42, 142, 242 Second conductive member 42f, 142f flange 42n Narrowed portion (portion located within the recess) 42p Cylindrical part 43, 143 Fastening part 45, 245 Ultrasonic joint 100 Electricity storage device 200 Energy Storage Module

Claims

1. a first conductive member made of a first metal and having a recess on a first surface; a second conductive member made of a second metal different from the first metal and having a portion disposed within the recess; an ultrasonic bonded portion at which the first conductive member and the second conductive member are ultrasonically bonded; Equipped with The first conductive member is provided on an outer circumferential side of the ultrasonic bonding portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface. Terminal for power storage device.

2. The second conductive member has a hollow tubular portion, a region of the first conductive member that overlaps with the cylindrical portion in an extension direction of the cylindrical portion is defined as a first region, and a region that is located inside the first region and in which the ultrasonic bonding portion is formed is defined as a second region, the rib being provided between the first region and the second region. The terminal according to claim 1 .

3. The second region does not protrude toward the second surface side beyond the first region. The terminal according to claim 2 .

4. The thickness T1 of the first region and the thickness T2 of the second region satisfy the following relationship: 0.8≦T1 / T2≦1.2; The terminal according to claim 2 or 3.

5. the second conductive member is made of copper or a copper alloy and has a flange portion; At least a portion of the flange portion is disposed within the recess of the first conductive member, The thickness T3 of the flange portion and the thickness T1 of the first region satisfy the following relationship: 3≦T3 / T1; The terminal according to claim 2 or 3.

6. The thickness T1 of the first region and the thickness T2 of the second region satisfy the following relationship: T1 / T2≦0.5; The terminal according to claim 2 or 3.

7. The ultrasonic bonding portion may further include a fastening portion at which the first conductive member and the second conductive member are mechanically fastened to each other on an outer circumferential side of the ultrasonic bonding portion. A terminal according to any one of claims 1 to 3.

8. an outer conductive member welded to the rib of the first conductive member; A terminal according to any one of claims 1 to 3.

9. an electrode body having a first electrode and a second electrode having a polarity different from that of the first electrode; A battery case that houses the electrode assembly; a terminal electrically connected to the first electrode and attached to the battery case; a current collecting member having a hole and electrically connecting the first electrode and the terminal inside the battery case, The terminal is a first conductive member made of a first metal and having a recess on a first surface; a second conductive member made of a second metal different from the first metal and having a portion disposed within the recess; an ultrasonic bonded portion at which the first conductive member and the second conductive member are ultrasonically bonded; Equipped with The first conductive member is provided on an outer circumferential side of the ultrasonic bonding portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, an inserting step of inserting a portion of the second conductive member of the terminal into the hole of the current collecting member; a crimping process of crimping a part of the second conductive member onto the current collecting member in a state in which a receiving jig is abutted against a part of the terminal outer periphery side of the rib after the insertion process; A method for manufacturing an electricity storage device, comprising:

10. In the inserting step, the terminal has the ultrasonic joint between the first conductive member and the second conductive member. A method for manufacturing the electricity storage device according to claim 9.

11. The second conductive member of the terminal has a hollow tubular portion, a region of the first conductive member that overlaps with the cylindrical portion in an extension direction of the cylindrical portion is defined as a first region, and a region that is located more inward than the first region and in which the ultrasonic bonding portion is formed is defined as a second region, the second region does not protrude toward the second surface side more than the first region, In the crimping step, the cylindrical portion of the second conductive member is crimped onto the current collecting member while a receiving jig is in contact with the second surface side of the first region. The method of claim 9.

12. The terminal has a thickness T1 of the first region and a thickness T2 of the second region that satisfy the following relationship: 0.8≦T1 / T2≦1.2; The method of claim 11.

13. the second conductive member of the terminal is made of copper or a copper alloy and has a flange portion; At least a portion of the flange portion is disposed within the recess of the first conductive member, The thickness T3 of the flange portion and the thickness T1 of the first region satisfy the following relationship: 3≦T3 / T1; The method of claim 11.

14. The terminal has a thickness T1 of the first region and a thickness T2 of the second region that satisfy the following relationship: T1 / T2≦0.5; The method of claim 11.

15. The terminal further includes a fastening portion at an outer circumferential side of the ultrasonic bonding portion, the fastening portion being configured to mechanically fasten the first conductive member and the second conductive member. The method of any one of claims 9 to 14.

16. the terminal further comprises an outer conductive member; The method further includes the steps of: after the crimping step, attaching the external conductive member to the rib by welding the external conductive member to the rib. The method of any one of claims 9 to 14.

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