Terminal for power storage device and method of manufacturing 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 (first and second conductive members) 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 and second conductive members to form a fastening portion, and a metal joining step of metal-joining the first and second conductive members 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] Japanese Patent Publication No. 2022-049729 Summary of the Invention [Problem to be solved by the invention]

[0004] For example, mechanical joining processes such as fastening and crimping processes can place stress on the conductive members and metal joints. This can lead to deformation of the conductive members or damage to the metal joints, making it difficult to stabilize the connection between the first conductive member and the second conductive member. This tendency is particularly pronounced when ultrasonically joining the first conductive member and the second conductive member to form the 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 circumstances, and aims to provide a terminal for an energy storage device that has an ultrasonic bonding portion and a highly reliable connection portion between a first conductive member and a second conductive member, and a method for manufacturing an energy storage device that includes 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 bonding portion at which the first conductive member and the second conductive member are ultrasonically bonded, wherein the first conductive member is located on the outer periphery of the ultrasonic bonding portion 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 explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view schematically illustrating an electricity storage device according to one embodiment. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a partially enlarged cross-sectional view schematically showing the vicinity of the negative electrode terminal. [Figure 4] FIG. 4 is a top view schematically showing a negative electrode terminal according to one embodiment. [Figure 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 schematically showing the connection between the negative electrode terminal and the external conductive member. [Figure 7] FIG. 7 is a perspective view schematically illustrating an electricity storage module according to one embodiment. [Figure 8] FIG. 8 is a vertical cross-sectional view schematically showing 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 INVENTION

[0009] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the drawings. It should be noted that matters other than those specifically mentioned in this specification that are necessary for implementing the present invention (for example, the general configuration and manufacturing process of an electricity storage device that do not characterize the present invention) can be understood as design matters for those skilled in the art based on prior art in the relevant field. The technology disclosed herein can be implemented based on the content disclosed in this specification and common technical knowledge in the relevant field.

[0010] <Electricity storage device 100> Fig. 1 is a perspective view of the energy storage device 100. Fig. 2 is a schematic longitudinal 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 of the energy storage device 100, the long side direction perpendicular to the short side direction, and the up-down direction, respectively. However, these directions are merely used for the convenience of 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 a general 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 collecting member 13, a negative electrode current collecting member 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 conventional devices. 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 the electrolyte (not shown) in a battery case 20.

[0013] The electrode assembly 10 may be the same as a conventional one and is not particularly limited. The electrode assembly 10 has a positive electrode and a negative electrode (not shown). The electrode assembly 10 is, for example, a flat wound electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state via a strip-shaped separator and wound around a winding axis. However, in other embodiments, the electrode assembly 10 may be a laminated electrode assembly in which a square-shaped (typically rectangular) positive electrode and a square-shaped (typically rectangular) negative electrode are stacked in an insulated state. 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." In particular, it is preferable that the negative electrode be 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 (e.g., a lithium transition metal composite oxide). The negative electrode has a negative electrode current collector 12 and a negative electrode mixture layer (not shown) fixed on the negative electrode current collector 12. The negative electrode current collector is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The negative electrode mixture layer contains a negative electrode active material (e.g., a carbon material such as graphite).

[0015] As indicated by the diagonal lines in FIG. 2 , a laminated portion is formed in the center of the electrode body 10 in the long side direction Y, where a positive electrode mixture layer and a negative electrode mixture layer are laminated in an insulated state. Meanwhile, at the left end of the electrode body 10 in the long side direction Y, a portion of the positive electrode current collector 11 where no positive electrode mixture layer is formed (exposed positive electrode current collector portion) protrudes from the laminated portion. A positive electrode current collector member 13 is attached to the exposed positive electrode current collector portion. The positive electrode current collector member 13 may be made of the same metal material as the positive electrode current collector 11, such as a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode current collector member 13 electrically connects the positive electrode to the positive electrode terminal 30 inside the battery case 20.

[0016] Furthermore, at the right end of the electrode body 10 in the long side direction Y, a portion of the negative electrode current collector 12 on which the negative electrode mixture layer is not formed (negative electrode current collector exposed portion) protrudes from the laminated portion. A negative electrode current collector 14 is attached to the negative electrode current collector exposed portion. The 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 conventional ones and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (nonaqueous electrolytic solution) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may be a solid (solid electrolyte) and integrated with the electrode assembly 10.

[0018] The battery case 20 is a housing that houses the electrode assembly 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 cylindrical shape. The material of the battery case 20 may be the same as that conventionally used 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 (sealing plate) 24 that closes the opening 22h. The battery case 20 preferably includes the case body 22 and the lid 24. The battery case 20 is integrated by joining (e.g., welding) the lid 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 here has a substantially rectangular shape. Note that in this specification, the term "substantially rectangular shape" is a term that encompasses not only a perfect rectangular shape (rectangular shape), but also 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 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 respectively disposed at both end portions of the lid 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 an electricity storage device." In particular, it is preferable that the negative electrode terminal 40 be a "terminal for an electricity storage device."

[0021] As shown in FIG. 2, the positive electrode terminal 30 is electrically connected to the positive electrode of the electrode assembly 10 via a positive electrode current collector 13 inside the battery case 20. The negative electrode terminal 40 is electrically connected to the negative electrode of the electrode assembly 10 via a negative electrode current collector 14 inside the 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 24). The positive electrode terminal 30 and the negative electrode terminal 40 are preferably fixed to the battery case 20 (specifically, the lid 24). The positive electrode terminal 30 and the negative electrode terminal 40 are each insulated from the lid 24 via a gasket 50 (see FIG. 3) and an insulator 60 (see FIG. 3).

[0022] 3 is a partially enlarged cross-sectional view schematically illustrating the vicinity of the negative electrode terminal 40. Note that, although the terminal structure on the negative electrode terminal 40 side will be described in detail below as an example, 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 24 is provided with a terminal pull-out hole 24h that penetrates 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 24. Although not shown, the terminal pull-out hole 24h here has a circular shape (for example, a perfect circle) in a plan view. The terminal pull-out hole 24h has an inner diameter large enough to allow the shaft portion 42s of the negative electrode terminal 40, described later, to be inserted therethrough before crimping. The terminal pull-out hole 24h is formed smaller than the flange portion 42f of the negative electrode terminal 40, described later.

[0024] The negative current collecting member 14 is attached to the exposed negative current collector portion of the negative current collector 12 and forms a conductive path that electrically connects the negative electrode and the negative terminal 40. The negative current collecting member 14 has a flat portion 14f that extends horizontally along the inner surface of the lid 24. The flat portion 14f has a hole 14h at a position corresponding to the terminal lead-out hole 24h. The hole 14h has an inner diameter large enough to allow the shaft portion 42s of the negative terminal 40, described below, to be inserted therethrough before crimping. 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. Here, the gasket 50 serves to insulate the lid 24 from the negative electrode terminal 40 and also to close the terminal withdrawal 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 lid 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 can be inserted therethrough before being crimped. The tubular portion 51 is inserted into a terminal lead-out hole 24h of the lid body 24. The base portion 52 is a portion that prevents direct contact between the lid body 24 and a flange portion 42f of the negative electrode terminal 40, which will be described later. The base portion 52 is connected to the upper end of the tubular portion 51. The base portion 52 extends horizontally from the upper end of the tubular portion 51. The base portion 52 is formed, for example, in an annular shape so as to surround the terminal lead-out hole 24h of the lid 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 electrode 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 extends 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 lead-out hole 24h. The hole 60h has an inner diameter large enough to allow the shaft portion 42s of the negative electrode terminal 40 to be inserted therethrough. The insulator 60 is made of an elastically deformable resin material that is resistant to the electrolyte used, has electrical insulating properties, and is, for example, a fluorinated resin such as perfluoroalkoxy fluororesin (PFA) or polyphenylene sulfide resin (PPS). The flat plate portion of the insulator 60 is sandwiched between the lower surface of the lid body 24 and the upper surface of the negative electrode current collecting member 14, and is compressed in the vertical direction Z by caulking.

[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 will be described later, the negative electrode terminal 40 is configured by integrating two types of conductive members, namely, 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 electrode terminal 40 is inserted into the terminal lead-out hole 24h of the lid 24 and the hole 14h of the negative electrode current collector 14, and its leading end (a cylindrical portion 42p, described later) in the insertion direction is crimped onto the negative electrode current collector 14. More specifically, it is crimped onto the peripheral portion surrounding the hole 14h of the negative electrode current collector 14. A crimped portion 40c is formed at the lower end of the negative electrode terminal 40. The negative electrode terminal 40 is fixed to the lid 24 and electrically connected to the negative electrode current collector 14 by crimping. In this example, the crimped portion 40c is cylindrical. However, the shape of the crimped portion 40c is not limited to a cylindrical shape and may be any shape, such as a columnar shape. The crimped portion 40c is preferably welded to the negative electrode current collector 14.

[0030] FIG. 4 is a schematic top view of the negative electrode terminal 40 before it is 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 bonding 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 that are connected using different methods, namely, the fastening portion 43 and the ultrasonic bonding portion 45. This makes it easier to maintain the first conductive member 41 and the second conductive member 42 in a tight contact state. This can more preferably improve the electrical conductivity reliability of the negative electrode terminal 40. 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 mass ratio; the same applies below).

[0032] As shown in FIG. 4, the first conductive member 41 has a circular shape (e.g., a perfect circle) in a 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, which will be 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 the surface facing the battery case 20 (specifically, the lid 24). The lower surface 41d is the surface that contacts the second conductive member 42. The upper surface 41u is the surface opposite the lower surface 41d in the thickness direction of the first conductive member 41 (the direction perpendicular to the lid 24). The upper surface 41u is the surface away from the battery case 20 and the second conductive member 42. The upper surface 41u is the surface to which an external conductive member 80 (see FIG. 6), which will be 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-walled portion 41t, and a rib 41s. However, in other embodiments, the first conductive member 41 may not have the thin-walled portion 41t and / or the second recess 41c. Furthermore, although the first conductive member 41 here does not have a through-hole, it may further have a through-hole as described in a second modified example below.

[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 has a circular shape (including a substantially circular shape with a partial cutout, for example, a perfect circle) in a plan view. 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 (specifically, a constricted portion 42n) of the second conductive member 42, which will be described later, 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 has a circular shape (for example, a 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 (the diameter in the case of a perfect circle, or 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 has a circular shape (e.g., a perfect circle) in a plan view. As shown in FIG. 5, the thin-walled portion 41t is formed to be thinner than its outer periphery. The thickness T2 of the thin-walled portion 41t is smaller than the thickness T of the first conductive member 41. Here, the thin-walled portion 41t is a region where the first recess 41r and the second recess 41c overlap in a plan view. Preferably, the thin-walled portion 41t is provided by forming the second recess 41c on the surface (i.e., the upper surface 41u) opposite the lower surface 41d on which the first recess 41r is formed, as in this embodiment. The thin-walled portion 41t has an ultrasonic bonding portion 45. This reduces the energy required during bonding, improving weldability. Furthermore, distortion and deformation of the first conductive member 41 can be minimized 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 (to be described later) in the direction (the vertical direction Z in FIG. 5) in which the cylindrical portion 42p extends. Here, the first region A1 is a region that overlaps with the cylindrical portion 42p in plan view. In other words, it is the region directly above the cylindrical portion 42p. Here, the first region A1 is in a ring shape (for example, an annular shape). The first upper surface S1 on the side opposite to the lower surface 41d of the first region A1 protrudes in a direction (upward in FIG. 5) away from the lower surface 41d (or the second conductive member 42) more than 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 (that is, T1 < T).

[0038] The second region A2 is located on the inner circumferential side of the first region A1 in the radial direction and is a region where the ultrasonic bonding portion 45 is formed. Here, the second region A2 is the thin portion 41t. The second region A2 is wider in the radial direction (the long side direction Y in FIG. 4) than the first region A1. Due to the second recess 41c, the second upper surface S2 (the bottom surface of the second recess 41c) on the side opposite to the lower surface 41d of the second region A2 is located below the first upper surface S1 of the first region A1. Preferably, the second region A does not protrude more toward the upper surface 41u side (upward in FIG. 4) than the first region A1. Thereby, less energy is required during bonding, and it becomes easier to stably form the ultrasonic bonding portion 45 in the second region A2. Also, during ultrasonic bonding, the distortion and deformation of the first conductive member 41 can be suppressed to a small level.

[0039] The thickness T2 of the second region A2 is smaller than the thickness T1 of the first region A1 by, for example, the amount of the second recess 41c (that is, T2 < T1 < T). The thickness T1 of the first region A1 and the thickness T2 of the second region A2 satisfy 2 / T 1 ≦0.5, which is preferable, and T 2 / T 1It is more preferable that the relationship <0.5 is satisfied. This allows the ultrasonic bonded portion 45 to be formed more stably in the second region A2. Furthermore, when the thickness T2 of the second region A2 is thin, the second region A2 is likely to be deformed or the ultrasonic bonded portion 45 is likely to be damaged, so applying the technology disclosed herein is particularly effective. However, as will be described in a second modified example below, 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.

[0040] The rib 41s protrudes from the upper surface (second surface) 41u. The rib 41s is provided on the outer circumferential side of the ultrasonic bonded portion 45. The rib 41s is provided on the inner circumferential 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, deformation of the second region A2 and damage to the ultrasonic bonded portion 45 can be suppressed during a manufacturing process (e.g., crimping of the terminal to the current collector, etc.) described below. This improves the reliability of the connection between the first conductive member 41 and the second conductive member 42. The rib 41s may be provided at a position spaced outward from the outer circumferential edge of the second recess 41c.

[0041] The rib 41s is preferably formed symmetrically with respect to the axis C of the first conductive member 41. Here, 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 portion 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. As will be described in detail later, when a plurality of energy storage devices 100 are electrically connected to each other to form 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 lead-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. In this example, the second conductive member 42 is made of copper. The second conductive member 42 is preferably made of a metal that has a higher Vickers hardness (is harder) than the first conductive member 41. The second conductive member 42 may be made of the same metal as the negative electrode current collecting member 14, or an alloy containing the same metal element as the first component. The second conductive member 42 may have a metal coating in which a metal such as Ni is coated on part or all of its 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 the side on which 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 within the first recess 41r of the first conductive member 41. It is preferable that at least a portion of the flange portion 42f of the second conductive member 42 is disposed within 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 outlet hole 24h of the lid 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 outlet hole 24h of the lid 24. Here, the flange portion 42f has a substantially cylindrical outer shape. The flange portion 42f is preferably circular (e.g., 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 formed by constricting a portion of the side surface 42o.

[0045] The constricted portion 42n is provided continuously or intermittently on a portion of the side surface 42o of the flange portion 42f. Preferably, the constricted portion 42n is 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 here has a ring shape (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 whose diameter increases 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. Here, the constricted portion 42n is fitted into the first recess 41r of the first conductive member 41 and fits into the first recess 41r. The constricted portion 42n is an example of a "portion disposed within 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 lid body 24, the shaft portion 42s is preferably inserted into the terminal lead-out hole 24h of the lid body 24. Although not shown, the shaft portion 42s has a cylindrical outer shape. 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 tubular portion 42p.

[0047] The cylindrical portion 42p here has a hollow cylindrical shape. The cylindrical portion 42p extends along the vertical 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 forms the crimped portion 40c. It is preferable that the cylindrical portion 42p be 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 together. The presence of the fastening portion 43 makes the connection between the first conductive member 41 and the second conductive member 42 more stable. The fastening portion 43 is provided on the outer periphery side of the ultrasonic bonding 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, thereby improving the conduction reliability of the negative electrode terminal 40.

[0049] The fastening portion 43 is configured such that a portion of the inner wall of the first recess 41r of the first conductive member 41 enters the constricted portion 42n of the second conductive member 42. This causes the inner wall of the first recess 41r of the first conductive member 41 to be fixed (e.g., pressed and fixed) to the constricted portion 42n of the second conductive member 42. The fastening portion 43 is preferably configured by fastening the inner wall of the first recess 41r of the first conductive member 41 to 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 for 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 is fitted into the constricted portion 42n of the second conductive member 42. 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 bonded portion 45 is a metal bonded portion formed by ultrasonically bonding the first conductive member 41 and the second conductive member 42. The ultrasonic bonded portion 45 is provided in the second region A2. The ultrasonic bonded portion 45 is provided more inward than the rib 41s. The ultrasonic bonded portion 45 is provided more inward than the tubular portion 42p. Here, the ultrasonic bonded portion 45 is provided in the thin-walled portion 41t. Here, the ultrasonic bonded portion 45 is provided at a position spaced apart from the fastening portion 43. The ultrasonic bonded portion 45 is provided more inward (closer to the center) than the fastening portion 43. The ultrasonic bonded portion 45 may be a bonded portion having relatively lower strength (more fragile) than the fastening portion 43. By disposing such an ultrasonic bonded portion 45 more inward than the fastening portion 43, the ultrasonic bonded portion 45 can be stably maintained, thereby improving the electrical conductivity reliability of the negative electrode terminal 40 over a long period of time. The ultrasonic bonded portion 45 can be clearly distinguished from, for example, laser welding by the pressure marks of the horn used in the ultrasonic bonding process described later.

[0052] The ultrasonic bonded portion 45 is formed continuously or intermittently in a plan view. The ultrasonic bonded portion 45 is preferably formed symmetrically with respect to the axis C of the first conductive member 41 and the second conductive member 42 (e.g., the flange portion 42f). In some preferred embodiments, the ultrasonic bonded portion 45 has a circular shape (e.g., a perfect circle) in a plan view, as shown in FIG. 4. This increases the strength of the ultrasonic bonded portion 45 and improves the conduction reliability of the negative electrode terminal 40. In addition, the area of ​​the ultrasonic bonded portion 45 can be increased, thereby reducing the conduction resistance and reducing the resistance. Furthermore, resistance heat can be suppressed, thereby reducing the thermal impact on resin members such as the gasket 50.

[0053] In some preferred embodiments, the negative electrode terminal 40 further includes an external conductive member 80 (see FIG. 6). FIG. 6 is a vertical cross-sectional view schematically illustrating the connection between the negative electrode terminal 40 and the external conductive member 80. As shown in FIG. 6, the external conductive member 80 is attached to the rib 41s of the first conductive member 41. Specifically, the external conductive member 80 is metal-bonded (e.g., 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 that constitutes the first conductive member 41. The external conductive member 80 is preferably made of aluminum or an aluminum alloy. Here, the external conductive member 80 is made of aluminum. The external conductive member 80 is preferably plate-shaped (more specifically, flat).

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

[0055] As shown in Figure 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 Figure 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 (e.g., a perfect circle). The welded joint 82 is preferably a laser welded joint. According to the inventors' investigations, 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, the metal joint between the external conductive member 80 and the first conductive member 41 can be prevented from reaching the second conductive member 42, thereby preventing a decrease in the reliability of the joint. This improves the electrical conductivity reliability of the energy storage module 200. However, the external conductive member 80 does not necessarily have to be attached to the rib 41s and can be attached to a location other than the rib 41s in other embodiments.

[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 presence of the extension portion 80b ensures a sufficient 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 connected directly 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 that includes, in this order, a fastening step of preparing a first conductive member 41 and a second conductive member 42, mechanically fastening the first conductive member 41 and the second conductive member 42 together, and an ultrasonic bonding step of ultrasonically bonding the first conductive member 41 and the second conductive member 42 together. By performing the bonding step after the fastening step, damage to the ultrasonic bonded portion 45 during the fastening step can be prevented, and an ultrasonic bonded portion 45 with a stable shape can be formed with high precision. However, the order of the fastening step and the bonding step may be reversed, or they may be performed approximately simultaneously. The manufacturing method disclosed herein may also include other steps at any stage.

[0059] In the fastening process, 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 deforming the first recess 41r of the first conductive member 41 to fit 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 together. 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 process.

[0060] In the ultrasonic bonding process, a portion of the second conductive member 42 (e.g., the flange portion 42f) is disposed in the first recess 41r of the first conductive member 41, and the second conductive member 42 is ultrasonically bonded to the second region A2 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-walled portion 41t. In ultrasonic bonding, for example, a horn is pressed against the second region A2 (specifically, the thin-walled portion 41t) of the first conductive member 41, and ultrasonic vibrations are applied while applying a pressing load. The ultrasonic bonding method and conditions may be the same as those used conventionally. Compared to laser welding, ultrasonic bonding is less likely to produce brittle intermetallic compounds at the bonding interface between the first conductive member 41 and the second conductive member 42. Therefore, a high-strength metal bonded portion can be reliably formed. Furthermore, 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 diverted to the rib 41s. Therefore, even if the first conductive member 41 does not have a through-hole, for example, it is possible to prevent unintended distortion or deformation of the first conductive member 41.

[0061] <Method of Manufacturing the Power 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 the manufacturing process may otherwise be the same as conventional. The electricity storage device 100 can be manufactured by a manufacturing method that includes, for example, preparing the electrode assembly 10, the electrolyte, the case body 22, the lid 24, the positive electrode terminal 30, and the negative electrode terminal 40 as described above, and performing a terminal attachment step and a case joining step in this order.

[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 together. The negative terminal 40 and the negative current collecting member 14 are fixed to the lid 24 by 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. Furthermore, other steps may be included at any stage. For example, the crimping step may be followed by an external conductive member attachment step, which will be described later.

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

[0064] In the crimping process, the second conductive member 42 of the negative terminal 40 is crimped onto the negative current collector 14. More specifically, the tubular portion 42p protruding from the hole 14h of the negative current collector 14 is crimped onto the negative current collector 14 so that a compressive force is applied in the vertical direction Z. The crimping process is performed with a gasket 50 sandwiched between the negative terminal 40 and the lid 24, and with an insulator 60 sandwiched between the lid 24 and the negative current collector 14. This forms a crimped portion 40c 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 schematically illustrating an example of this step. Note that FIG. 8 does not illustrate the lid 24, the gasket 50, the insulator 60, and the negative electrode current collecting member 14. In some preferred embodiments, first, as shown in FIG. 8, a crimping device including a punch (press jig) 91 and a die (receiving jig) 92 is prepared. The die 92 here has a hollow cylindrical shape and has a hollow portion 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 upside down on the top surface of the die 92. 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 outer peripheral side of the upper surface 41u of the first conductive member 41 is in contact with the die 92.

[0066] In this embodiment, the first conductive member 41 has a second recess 41c on its upper surface 41u. The first region A1 of the first conductive member 41 protrudes toward the upper surface 41u 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 which the first recess 41r is formed) 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 portion 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 bonded portion 45 is formed is floating above the die 92. The second conductive member 42 does not abut against the die 92. This more effectively prevents the ultrasonic bonded portion 45 from being damaged.

[0067] Next, with the outer periphery of the rib 41s, specifically at least a portion of the first upper surface S1 of the first region A1, in contact with the die 92, the tip of the punch 91 is inserted into the cylindrical portion 42p (hollow portion) of the second conductive member 42. 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), thereby expanding and deforming the cylindrical portion 42p with the tip of the punch 91. This causes the cylindrical portion 42p to plastically deform so as to embrace the outer edge portion. As a result, a crimped portion 40c is formed on the negative electrode current collecting member 14, and the various components are crimped and fixed.

[0068] In this embodiment, a rib 41s is provided in the first conductive member 41 between the first region A1 and the second region A2. This effectively prevents deformation of the second region A2 and damage to the ultrasonic bonding portion 45 provided in the second region A2 during this process. Therefore, a highly reliable terminal is formed at the connection between the first conductive member 41 and the second conductive member 42. Note that in this embodiment, the first conductive member 41 does not have a through-hole, which increases the area of ​​the ultrasonic bonding portion 45 and reduces the conduction resistance, thereby reducing resistance. Furthermore, resistance heat can be suppressed, thereby reducing the thermal impact on resin members such as the gasket 50.

[0069] Additionally, in this embodiment, the first region A1 protrudes toward the upper surface 41u 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, because the second region A2 is recessed toward the lower surface 41d 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 bonded portion 45 is formed. This allows for a greater reduction in the load on the second region A2 and the ultrasonic bonded portion 45 provided in the second region A2, and more effectively prevents damage to the ultrasonic bonded portion 45.

[0070] The above-described crimping process compresses the base 52 of the gasket 50 and the flat portion of the insulator 60, integrally fixing the gasket 50, the lid 24, the insulator 60, and the negative current collecting member 14 to the lid 24, and sealing the terminal lead-out hole 24h. The negative current collecting member 14 is welded to the exposed negative current collector portion of the negative current collector 12, electrically connecting the negative electrode of the electrode assembly 10 to the negative electrode terminal 40. The attachment method of the positive electrode terminal 30 and the positive current collecting member 13 may be similar to that of the negative electrode terminal 40 and the negative electrode current collecting member 14 described above. The positive current collecting member 13 is welded to the exposed positive current collector portion of the positive current collector 11, electrically connecting the positive electrode of the electrode assembly 10 to the positive electrode terminal 30. This integrates the lid 24, the positive electrode terminal 30, the negative electrode terminal 40, and the electrode assembly 10.

[0071] In some embodiments, the crimping step is followed by an external conductive member attachment step of attaching (e.g., welding) the external conductive member 80 to the negative terminal 40. 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, at the peripheral edge 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 assembly 10 integrated with the lid 24 is housed in the internal space of the case body 22, and the lid 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). This seals the opening 22h of the case body 22, and integrates the case body 22 and the lid 24. Thereafter, a nonaqueous electrolyte is poured through a liquid filling port (not shown), and the liquid filling 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 a variety of purposes, and is preferably 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 include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs). The power storage device 100 can also be preferably used as a power storage module 200 in which a plurality of power storage devices 100 are electrically connected to one another via bus bars 90 (see FIG. 7 ).

[0074] FIG. 7 is a perspective view that schematically illustrates an energy storage module 200 according to one embodiment. As illustrated in FIG. 7, the energy storage module 200 includes a plurality of energy storage devices 100 and a bus bar 90 that electrically connects the first energy storage device 100 and the second energy 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 bridges the positive terminal 30 of the first energy storage device 100 and the negative terminal 40 of the second energy storage device 100 via an extension 80b of an external conductive member 80. The bus bar 90 is preferably welded (e.g., 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 common general technical knowledge in the relevant field. The technology described in the claims includes various modifications and alterations of the above-exemplified embodiments. For example, it is possible to replace part of the above-described embodiments with other modified embodiments, and it is also possible to add other modified embodiments to the above-described embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0076] (1) For example, in FIG. 4 of the above-described 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 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 connected directly to the extension portion of the first conductive member 41 without using the external conductive member 80.

[0077] (2) For example, in the embodiment shown in Fig. 5, the constricted portion 42n is provided in a portion 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, on a portion other than the side surface 42o.

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

[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 is large in the region overlapping with the tubular portion 42p (the region compressed in the crimping process). 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 and the ultrasonic bonded portion 45 provided in the second region A2 can be reduced to a higher level, and damage to the ultrasonic bonded portion 45 can be more effectively prevented.

[0080] (3) For example, in FIG. 5 of the above-described embodiment, the first conductive member 41 does not have a through hole 41h, and the ultrasonic bonding portion 45 is circular in plan view. Furthermore, 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 in 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 substantially the same height.

[0081] 10 is a view corresponding to FIG. 5 according to a 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 bonding 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 thinner overall than that shown in FIG. 5. The second conductive member 242 may be similar to the second conductive member 42 except that a flange portion 242f is formed thicker than that shown in 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, 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 separated 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 separated positions.

[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 caulking, 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 damage to the ultrasonic bonding portion 45 can be effectively suppressed. 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 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 the relationship 3≦T3 / T1. By making the thickness of the flange portion 42f larger than the thickness T1 of the first region A1, unintended deformation can be prevented when the tubular portion 42p (described later) is crimped. In addition, the application of a load to the ultrasonic bonding portion 45 can be prevented.

[0086] (4) For example, in the above-described 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, a 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 bonding portion at which the first conductive member and the second conductive member are ultrasonically bonded, wherein the first conductive member is located on the outer periphery of the ultrasonic bonding portion 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 cylindrical portion, and when a region of the first conductive member that overlaps with the cylindrical portion in the direction in which the cylindrical 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. Term 6: The thickness T1 of the first region and the thickness T2 of the second region have the following relationship: T 2 / T 1 Item 2 or 3. The terminal according to item 2 or 3, which satisfies the following: 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 bonding portion, where the first conductive member and the second conductive member are mechanically fastened together. 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 accommodating the electrode assembly, a terminal electrically connected to the first electrode and attached to the battery case, and a current collecting member having a hole and electrically connecting 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 in the recess, and a current collecting member between 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, wherein the first conductive member is disposed on the outer periphery of the ultrasonic bonding portion and has a rib protruding from a second surface of the first conductive member opposite to 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 after the insertion step, with a receiving jig abutted on the outer periphery of the rib of the terminal. Item 10: The manufacturing method according to Item 9, wherein in the inserting step, the terminal has the ultrasonic bonded portion 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 cylindrical portion, and when a region of the first conductive member that overlaps with the cylindrical portion in the direction in which the cylindrical 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 further toward the second surface than the first region, and in the crimping process, the cylindrical 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 terminal has a thickness T1 of the first region and a thickness T2 of the second region that satisfy the following relationship: T 2 / T 1 Item 12. The manufacturing method according to item 11, wherein the β-glucan group satisfies ≦0.5; Item 15: The manufacturing method according to any one of items 9 to 14, wherein the terminal further includes a fastening portion where the first conductive member and the second conductive member are mechanically fastened together on the outer circumferential side of the ultrasonic bonding portion. Item 16: The manufacturing method according to any one of items 9 to 15, wherein the terminal further comprises 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 collecting member (current collecting member) 20 Battery case 24 Lid 40, 140, 240 Negative terminal (terminal) 40c Crimped 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 Necked 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 bonded portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, the second conductive member has a hollow cylindrical portion, When a region of the first conductive member that overlaps with the cylindrical portion in the extending 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 is provided between the first region and the second region and protrudes further from the second surface in the first region than the second conductive member, The entire rib is disposed closer to the second region than the first region, or a part of the rib is disposed in the first region, and the ratio of the formation area of ​​the rib to the area of ​​the first region is less than 0.

5. Terminal for power storage device.

2. The second region does not protrude further toward the second surface than the first region. The terminal according to claim 1 .

3. a thickness T1 of the first region and a thickness T2 of the second region satisfy the following relationship: 0.8≦T1 / T2≦1.2; The terminal according to claim 1 .

4. The thickness T1 of the first region and the thickness T2 of the second region satisfy the following relationship: T2 / T1≦0.

5. The terminal according to claim 1 .

5. 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 4.

6. further comprising an outer conductive member welded to the rib of the first conductive member; A terminal according to any one of claims 1 to 4.

7. 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 bonded portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, the second conductive member has a hollow cylindrical portion, When a region of the first conductive member that overlaps with the cylindrical portion in the extending 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 is provided between the first region and the second region and protrudes further from the second surface in the first region than the second conductive member, 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; Terminal for power storage device.

8. 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 bonded portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, the second conductive member has a hollow cylindrical portion, When a region of the first conductive member that overlaps with the cylindrical portion in the extending 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 is provided between the first region and the second region and protrudes further from the second surface in the first region than the second conductive member, the first conductive member has a second recess on the inner side of the rib that is recessed toward the second conductive member relative to the second surface located on the outer side of the rib; Terminal for power storage device.

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 bonded portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, the second conductive member has a hollow cylindrical portion, When a region of the first conductive member that overlaps with the cylindrical portion in the extending 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 is provided between the first region and the second region and protrudes further from the second surface in the first region than the second conductive member, a method for manufacturing an electric storage device, wherein the entire rib is disposed closer to the second region than the first region, or a part of the rib is disposed in the first region, and a ratio of a formation area of ​​the rib to an area of ​​the first region is less than 0.5, an insertion step of inserting a portion of the second conductive member of the terminal into the hole of the current collecting member; a crimping step of crimping a portion of the second conductive member onto the current collecting member in a state in which a receiving jig is brought into contact with the terminal on an outer circumferential side of the rib after the insertion step; A method for manufacturing an electricity storage device, comprising:

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

11. The second region of the terminal does not protrude further toward the second surface 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 brought into 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 9.

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 9.

14. The terminal has a thickness T1 of the first region and a thickness T2 of the second region satisfying the following relationship: T2 / T1≦0.

5. The method of claim 9.

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

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

17. 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 bonded portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, an external conductive member having a through hole is disposed on the second surface; the rib of the first conductive member is disposed within the through hole of the external conductive member; A method for manufacturing an electricity storage device, in which the external conductive member and the rib are joined, an insertion step of inserting a portion of the second conductive member of the terminal into the hole of the current collecting member; a crimping step of crimping a portion of the second conductive member onto the current collecting member in a state in which a receiving jig is brought into contact with the terminal on an outer circumferential side of the rib after the insertion step; an external conductive member attaching step of, after the crimping step, placing the external conductive member on the second surface of the terminal and joining the external conductive member to the rib; A method for manufacturing an electricity storage device, comprising:

18. A method for manufacturing an energy storage module in which a plurality of energy storage devices are electrically connected via bus bars, comprising: A method for manufacturing an electric storage module, comprising the step of joining the bus bar to the external conductive member of the electric storage device obtained by the manufacturing method according to claim 17.

19. 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 bonded portion and includes a rib protruding from a second surface of the first conductive member opposite to the first surface, the first conductive member has a through hole; The ultrasonic bonding portion is formed around the through hole. Terminal for power storage device.

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