Manufacturing method of terminal for power storage device and manufacturing method of power storage device

Abstract

To provide a manufacturing method of a terminal for a power storage device, by which a connection state between a first conductive member and a second conductive member becomes stable.SOLUTION: The invention provides a manufacturing method of a terminal including a first conductive member 41 that is formed of a first metal and includes a concave part and a through hole 41h, a second conductive member 42 that is formed of a second metal and includes a part disposed in the concave part, 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 in a periphery of the through hole 41h. This manufacturing method includes a disposing step in which a part of the second conductive member 42 is disposed in the concave part of the first conductive member 41, and a bonding step in which the periphery of the through hole 41h of the first conductive member 41 is joined to the second conductive member 42 with ultrasonic waves after the disposing step.SELECTED DRAWING: Figure 9

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a terminal for an electricity storage device and a method for manufacturing an electricity storage device. [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 (see Patent Documents 1 and 2). For example, Patent Document 1 discloses a method for manufacturing a terminal, including an ultrasonic joining process for ultrasonically joining the first conductive member and the second conductive member to form an ultrasonic joint, and a crimping process for crimping (mechanically fastening) the first conductive member and the second conductive member to form a fastening portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-124024 A [Patent Document 2] JP 2022-049729 A Summary of the Invention [Problem to be solved by the invention]

[0004] In ultrasonic bonding, a horn is pressed against one of the conductive members, and ultrasonic vibration is applied while applying a pressing load. According to the inventor's research, the conductive member against which the horn is pressed may be distorted or deformed unintentionally. As a result, it may become difficult to perform the crimping process, or the previously formed fastening portion may be damaged, making it difficult to stabilize the connection between the first conductive member and the second conductive member.

[0005] The present invention has been made in consideration of the above circumstances, and aims to provide a method for manufacturing a terminal for an energy storage device and a method for manufacturing an energy storage device that tend to stabilize the connection state between a first conductive member and a second conductive member. [Means for solving the problem]

[0006] According to the present invention, there is provided a method for manufacturing a terminal for an electric storage device, the terminal including: a first conductive member made of a first metal and having a recess on a first surface and a through hole provided in the recess; a second conductive member made of a second metal different from the first metal and having a portion disposed in the recess; an ultrasonic joint portion in which the first conductive member and the second conductive member are ultrasonically joined around the through hole; and a fastening portion in which the first conductive member and the second conductive member are mechanically fastened on an outer circumferential side of the ultrasonic joint portion. The manufacturing method includes an arrangement step of arranging a portion of the second conductive member in the recess of the first conductive member, and a joining step of ultrasonically joining the periphery of the through hole of the first conductive member to the second conductive member after the arrangement step.

[0007] According to the above manufacturing method, a stable connection state between the first conductive member and the second conductive member can be suitably achieved. [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 typically shows the vicinity of the negative electrode terminal. [Figure 4] FIG. 4 is a perspective view that illustrates a negative electrode terminal according to one embodiment. [Diagram 5] FIG. 5 is a schematic side view of the negative electrode terminal of FIG. [Figure 6] FIG. 6 is a schematic vertical cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 7 is a partially enlarged cross-sectional view showing a schematic view of a main part of FIG. [Figure 8] FIG. 8 is a perspective view that illustrates a battery pack according to one embodiment. [Figure 9] FIG. 9 is a vertical cross-sectional view that illustrates an example of the bonding step. [Figure 10] FIG. 10 is a vertical cross-sectional view that illustrates an example of the crimping step. [Figure 11] FIG. 11(A) is a plan view that shows a schematic diagram of an ultrasonic bonding unit according to a modified example, and FIG. 11(B) is an explanatory diagram that explains the relationship between the vibration direction and the arrangement of a horn. [Figure 12] FIG. 12A is a view corresponding to FIG. 10 according to a first modified example, and FIG. 12B is a view corresponding to FIG. 10 according to a 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> First, a description will be given of an energy storage device manufactured by the manufacturing method disclosed herein. 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.

[0011] 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.

[0012] As shown in FIG. 2, the power storage device 100 includes an electrode assembly 10, a battery case 20, a positive electrode terminal 30, and a negative electrode terminal 40. The power 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 power storage device 100 is preferably a secondary battery, and more preferably a non-aqueous electrolyte secondary battery. Here, the power storage device 100 is a lithium ion secondary battery. Although not shown, the power storage device 100 further includes an electrolyte. The power 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".

[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 material (metal type) of the negative electrode current collector 14 may be different from that of the positive electrode current collector 13. The negative electrode current collector 14 may be made of the same metal type as the negative electrode current collector 12, for example, a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The negative electrode current collector 14 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 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 respectively disposed at both end portions 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".

[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 formed with a terminal pull-out hole 24h penetrating in the up-down direction Z. 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 (for example, perfect circle) in a 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 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> As shown in FIG. 3, the negative terminal 40 extends from the inside to the outside of the battery case 20 through the terminal pull-out hole 24h. As described later, the negative terminal 40 is configured by integrating two types of conductive members, that is, a first conductive member 41 and a second conductive member 42, with a fastening portion 43 and an ultrasonic joint 45. 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 portion 14h of the negative current collector 14, and the tip portion (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 portion 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 by crimping and is electrically connected to the negative current collector 14. Here, the crimped portion 40c is cylindrical. However, the shape of the crimped portion 40c is not limited to cylindrical, and may be any shape such as columnar. It is preferable to weld the crimped portion 40c to the negative electrode current collecting member 14.

[0029] FIG. 4 is a schematic perspective view of the negative electrode terminal 40 before being attached to the cover 24 (i.e., before crimping). FIG. 5 is a schematic side view of the negative electrode terminal 40 of FIG. 4. FIG. 6 is a schematic vertical cross-sectional view along the line VI-VI of FIG. 4. FIG. 7 is a partially enlarged cross-sectional view showing a schematic main part of FIG. 6. As shown in FIG. 6, 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 the fastening portion 43 and the ultrasonic joint portion 45.

[0030] 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).

[0031] The first conductive member 41 is preferably plate-shaped (specifically, flat). As shown in FIG. 4, the first conductive member 41 is substantially rectangular having short and long sides in plan view. As shown in FIG. 6, the thickness T1 of the first conductive member 41 is preferably 0.5 to 5 mm, more preferably 1 to 3 mm, for example, 1.8 mm. The thickness T1 of the first conductive member 41 is preferably smaller than the length of the short side in plan view. 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 away from the battery case 20 and the second conductive member 42.

[0032] 4 and 5, the first conductive member 41 is divided into two regions in the long side direction Y, and has a connection portion 41a electrically connected to the second conductive member 42, and an extension portion 41b extending from the connection portion 41a to one side in the long side direction Y (to the left in FIG. 4). As shown in FIG. 6, the connection portion 41a here has a first recess 41r, a through hole 41h, a thin portion 41t, and a second recess 41c. However, in other embodiments, the connection portion 41a may not have the thin portion 41t and / or the second recess 41c.

[0033] As shown in FIG. 6, the first recess 41r is provided on the lower surface (first surface) 41d. Although not shown, in a plan view, the first recess 41r is in a ring shape (for example, annular) surrounding the through hole 41h. Although not particularly limited, the outer diameter Wr of the first recess 41r (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 6 mm or more. Here, 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 flange portion 42f (specifically, a constricted portion 42n) of the second conductive member 42 described later is inserted into the first recess 41r. The first recess 41r is an example of a "recess on the first surface".

[0034] The through hole 41h is provided in the first recess 41r as shown in FIG. 4. The through hole 41h penetrates the first conductive member 41 in the up-down direction Z. The through hole 41h is preferably provided in the thin-walled portion 41t, and more preferably in the center of the thin-walled portion 41t. On the upper surface 41u of the first conductive member 41, the second conductive member 42 (specifically, a flange portion 42f described later) is exposed from the through hole 41h. The through hole 41h is circular (for example, perfect circle) in plan view here. Although not particularly limited, as shown in FIG. 6, the outer diameter Wh of the through hole 41h (diameter in the case of a perfect circle, the shortest length passing through the center in the case of a non-perfect circle) is typically smaller than the outer diameter Wr of the first recess 41r, and is preferably 5 to 7 mm, for example. The through hole 41h is provided on the inner periphery side (center side) of the fastening portion 43 and the ultrasonic bonding portion 45.

[0035] As shown in FIG. 4, the thin-walled portion 41t is provided around the through-hole 41h. Here, the thin-walled portion 41t is ring-shaped (for example, annular) in plan view. As shown in FIG. 6, the thin-walled portion 41t is formed to be thinner than its outer circumferential portion (for example, the extension portion 41b). That is, the thickness Tt of the thin-walled portion 41t is smaller than the thickness T1 of the first conductive member 41. The thickness Tt of the thin-walled portion 41t is smaller than the thickness Tf of the portion of the flange portion 42f that protrudes from the first recess 41r, which will be described later. Here, the thin-walled portion 41t is a region where the first recess 41r and the second recess 41c overlap in plan view. It is preferable that the thin-walled portion 41t is 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. Although not particularly limited, the outer diameter Wt of the thin-walled portion 41t (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 preferably, for example, 7 to 14 mm. The outer diameter Wt of the thin-walled portion 41t is smaller than the outer diameter Wr of the first recess 41r here. The thin-walled portion 41t is provided with an ultrasonic bonding portion 45. This allows the ultrasonic bonding portion 45 to be formed more stably.

[0036] The second recess 41c is provided on the upper surface (second surface) 41u. As shown in Fig. 4, the second recess 41c is in a ring shape (for example, annular) surrounding the through hole 41h in plan view. Although not particularly limited, the outer diameter of the second recess 41c in plan view (here, the same as the outer diameter Wt of the thin-walled portion 41t, 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 smaller than the outer diameter Wr of the first recess 41r.

[0037] The extension portion 41b is a portion to which a bus bar 90 (see FIG. 8), which is a conductive member, is attached when, for example, a plurality of power storage devices 100 are electrically connected to one another to produce a battery pack 200 (see FIG. 8). The presence of the extension portion 41b makes it possible to ensure a sufficient ground contact area with the bus bar 90, thereby improving the electrical conductivity reliability of the battery pack 200.

[0038] 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.

[0039] The second conductive member 42 has an axis C, as shown in Figs. 5 and 6. 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 preferably has the flange portion 42f disposed in the first recess 41r of the first conductive member 41.

[0040] 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 cover 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 cover 24. The outer shape of the flange portion 42f is a substantially cylindrical shape here. As shown in FIG. 6, the axis of the flange portion 42f coincides with the axis C of the second conductive member 42. The thickness Tf of the portion of the flange portion 42f that protrudes from the first recess 41r is preferably 0.5 to 5 mm, more preferably 1 to 3 mm, and is, for example, 2.0 mm. Here, the thickness Tf is larger than the thickness T1 of the first conductive member 41. The thickness Tf of the portion of the flange portion 42f that protrudes from the first recess 41r and the thickness Tt of the thin-walled portion 41t of the first conductive member 41 preferably satisfy the following formula: Tf / Tt>3. This makes it possible to more stably form high-strength ultrasonic joint 45. Flange portion 42f has a lower surface 42d, a side surface (outer peripheral surface) 42o extending upward from lower surface 42d, and a constricted portion 42n formed by constricting a portion of side surface 42o.

[0041] 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".

[0042] 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, the shaft portion 42s is preferably inserted into the terminal lead-out hole 24h of the cover body 24 when the negative electrode terminal 40 is attached to the cover body 24. As shown in FIG. 5 and FIG. 6, 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, that is, the end opposite to the side where the flange portion 42f is located, is hollow. The lower end of the shaft portion 42s constitutes the tubular portion 42p. The tubular portion 42p has a hollow cylindrical shape here. The tubular portion 42p extends along the vertical direction Z. The cylindrical portion 42p is a portion that constitutes the crimped portion 40c and is expanded by crimping when the negative terminal 40 is attached to the lid 24. It is preferable that the cylindrical portion 42p is electrically connected to the negative current collecting member 14 inside the battery case 20 by crimping.

[0043] The fastening portion 43 is a connecting portion where the first conductive member 41 and the second conductive member 42 are mechanically fastened. The fastening portion 43 is provided on the outer periphery side of the ultrasonic joint portion 45 in the radial direction of the through hole 41h. 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 into 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) by 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. The fastening portion 43 is formed continuously here. The fastening portion 43 is ring-shaped (for example, annular) in a plan view here. This increases the strength of the fastening portion 43, and improves the electrical connection reliability of the negative electrode terminal 40.

[0044] 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 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. This allows the first conductive member 41 and the second conductive member 42 to be suitably fixed together even if, for example, the first conductive member 41 and the second conductive member 42 are made of different metals. 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.

[0045] 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 around the through hole 41h. Here, the ultrasonic joint 45 is provided at a position spaced apart from the through hole 41h. Here, the ultrasonic joint 45 is provided on the thin-walled portion 41t. Here, the ultrasonic joint 45 is provided at a position spaced apart from the fastening portion 43. The ultrasonic joint 45 is provided on the inner circumferential side (center side) of the fastening portion 43 in the radial direction of the through hole 41h. The ultrasonic joint 45 can 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 circumferential 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.

[0046] 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 second conductive member 42 (e.g., the flange portion 42f). In some preferred embodiments, the ultrasonic joint 45 is preferably formed continuously along the circumferential direction of the through hole 41h as shown in FIG. 4. The ultrasonic joint 45 is preferably ring-shaped (e.g., annular) in plan view. This can increase the strength of the ultrasonic joint 45 and improve the conduction reliability of the negative electrode terminal 40.

[0047] As described above, the negative electrode terminal 40 includes two types of connecting parts with different connecting methods, namely, the ultrasonic bonding part 45 and the fastening part 43 provided on the outer circumferential side of the ultrasonic bonding part 45. This makes it easier to maintain the first conductive member 41 and the second conductive member 42 in a close contact state. Therefore, the conductive connection between the first conductive member 41 and the second conductive member 42 can be stably maintained, and the conductive reliability of the negative electrode terminal 40 can be improved.

[0048] <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 a first conductive member 41 and a second conductive member 42, mechanically fastening the first conductive member 41 and the second conductive member 42, and a 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, an ultrasonic bonded portion 45 having a stable shape can be formed 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.

[0049] 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. This step includes an arrangement step of arranging a part of the second conductive member 42 (for example, a portion including the narrowed portion 42n) in the first recess 41r of the first conductive member 41. In other words, this step also serves as an arrangement step. The fastening portion 43 can be formed, for example, by arranging the narrowed 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 along the outer shape of the narrowed portion 42n of the second conductive member 42 to fix 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 the first recess 41r of the first conductive member 41 and the narrowed portion 42n of the second conductive member 42 together. For example, it can be formed by horizontally press-fitting the narrowed 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.

[0050] In the joining process, with a part of the second conductive member 42 disposed in the first recess 41r of the first conductive member 41, the periphery of the through hole 41h of the first conductive member 41 is ultrasonically joined with the second conductive member 42 to form an ultrasonic joint 45. In ultrasonic joining, brittle intermetallic compounds are less likely to be generated at the joining interface between the first conductive member 41 and the second conductive member 42 than in laser welding, for example. Therefore, a high-strength metal joint can be stably formed. In some preferred embodiments, the ultrasonic joint 45 is formed by ultrasonically joining the thin-walled portion 41t of the first conductive member 41 with the second conductive member 42 (for example, the flange portion 42f). This makes it easier to stably form the ultrasonic joint 45. In addition, less energy is required during joining, so distortion and deformation of the first conductive member 41 can be suppressed to a smaller extent.

[0051] 9 is a vertical cross-sectional view showing this step. In some preferred embodiments, an ultrasonic bonding device including a horn 81 and an anvil 82 (receiving jig) is first prepared. The horn 81 has an annular foot 81a. Although not shown, the horn 81 is attached to a press device and an ultrasonic oscillator. The horn 81 is configured to apply ultrasonic vibration to the objects to be bonded in a predetermined vibration direction. The anvil 82 is attached to the press device so as to face the horn 81. The anvil 82 has an outer shape that can be accommodated in the cylindrical portion 42p (hollow portion) of the second conductive member 42 here.

[0052] Next, as shown in FIG. 9, the periphery of the through hole 41h of the first conductive member 41 (here, the thin-walled portion 41t) and the portion of the second conductive member 42 arranged in the first recess 41r of the first conductive member 41 (here, a part of the flange portion 42f) are sandwiched between the horn 81 and the anvil 82. In this embodiment, the foot portion 81a of the horn 81 is abutted against the thin-walled portion 41t of the first conductive member 41, and the anvil 82 is abutted against the shaft portion 42s of the second conductive member 42. The anvil 82 is inserted into the cylindrical portion 42p of the second conductive member 42. In this state, ultrasonic vibration is applied while applying a pressing load by the horn 81. Then, the first conductive member 41 against which the horn 81 is pressed vibrates in sync with the horn 81.

[0053] The conditions of the indentation load and ultrasonic vibration are design matters that can be appropriately adjusted, for example, depending on the material and dimensions of the first conductive member 41 and the second conductive member 42, the shape of the horn 81, and the like. Therefore, although not particularly limited, in some embodiments, the indentation load is preferably about 500 to 2000 N, and more preferably 800 to 1200 N. The frequency of the ultrasonic vibration applied to the first conductive member 41 through the horn 81 is preferably about 10 to 50 kHz, and more preferably 15 to 25 kHz. The oscillation time of the ultrasonic vibration is preferably about 0.5 to 1.5 sec, and more preferably 0.7 to 1.0 sec. The vibration direction of the horn 81 may be, for example, the short side direction X or the long side direction Y.

[0054] In the region where the force of pressing the horn 81 acts due to ultrasonic vibration, the bonding interface between the first conductive member 41 (thin wall portion 41t here) and the second conductive member 42 (flange portion 42f here) is solid-phase welded. As a result, an ultrasonic bond 45 is formed around the through hole 41h. Here, since the foot portion 81a of the horn 81 is annular, the ultrasonic bond 45 is formed continuously (annularly) along the circumferential direction of the through hole 41h. In some embodiments, as shown in FIG. 6, for example, the inner diameter Wi of the ultrasonic bond 45 is preferably 7 to 12 mm, and the outer diameter Wo of the ultrasonic bond 45 is preferably 8 to 13 mm.

[0055] By placing a part of the second conductive member 42 in the first recess 41r of the first conductive member 41, the reliability of the connection between the first conductive member 41 and the second conductive member 42 when the first conductive member 41 and the second conductive member 42 are in a terminal state is improved. In addition, by performing ultrasonic bonding around the through hole 41h as in the embodiment, even when a part of the second conductive member 42 is placed in the first recess 41r of the first conductive member 41, the area to be ultrasonically bonded in the first conductive member 41 can be smoothly vibrated. Therefore, less energy is required, and the first conductive member 41 is less likely to deform. In addition, even if the first conductive member 41 is deformed, the through hole 41h can absorb the deformation (absorb the flow of flesh), and the first conductive member 41 can be prevented from being unintentionally distorted or deformed. Therefore, a stable connection state between the first conductive member 41 and the second conductive member 42 can be preferably realized. This results in a more reliable terminal or electricity storage device. Furthermore, when ultrasonically joining the first conductive member 41 and the second conductive member 42, it is particularly effective if the first conductive member 41 and the second conductive member 42 are fixed by the fastening portion 43 on the outer circumferential side of the ultrasonic joining portion.

[0056] In the first embodiment, when the width of the thin portion 41t is large, for example, 7 mm or more, and further 10 mm or more, it is preferable to press the leg portion 81a of the horn 81 against the vicinity of the through hole 41h. Thereby, stress can be absorbed by the through hole 41h and the thin portion 41t, and the first conductive member 41 can vibrate more smoothly. Further, unintentional large deformation of the first conductive member 41 can be better suppressed. In addition, by forming the ultrasonic bonding portion 45 near the through hole 41h (in other words, by forming the ultrasonic bonding portion 45 at a location away from the fastening portion 43), the load from the bus bar 90 (see FIG. 8) can be reduced. Therefore, even when an external force such as vibration or impact is applied during the use of the power storage device 100, the conductive connection between the first conductive member 41 and the second conductive member 42 can be stably maintained, and the conduction reliability of the negative electrode terminal 40 can be improved.

[0057] From such a viewpoint, in the first embodiment, as shown in FIG. 7, in the radial direction of the through hole 41h, when the distance between the through hole 41h and the inner peripheral edge of the ultrasonic bonding portion 45 is D1, and the distance between the outer peripheral edge of the ultrasonic bonding portion 45 and the outer peripheral edge of the thin portion 41t is D2, it is preferable to form the ultrasonic bonding portion 45 such that D1 is smaller than D2. That is, it is preferable that D1 < D2. By bringing the ultrasonic bonding portion 45 closer to the through hole 41h in this way, a high-strength ultrasonic bonding portion 45 can be formed more stably, and the above-described effects can be exhibited at a higher level. From such a viewpoint, D1 / D2 is preferably less than 1, more preferably less than 0.8, and even more preferably less than 0.5. D1 is preferably, for example, 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less. Further, in the radial direction of the through hole 41h, the ratio (W2 / W1) of the width W2 of the thin portion 41t to the width W1 of the ultrasonic bonding portion 45 is preferably 1 or more, and more preferably exceeds 1.

[0058] In the first embodiment, as shown in FIG. 6, the difference (Wi-Wh) between the inner diameter Wi of the ultrasonic bonding portion 45 and the outer diameter Wh of the through hole 41h is preferably 5 mm or less, more preferably 2 mm or less. The ultrasonic bonding portion 45 is preferably separated from the through hole 41h. The difference (Wi-Wh) is preferably 0.1 mm or more. In addition, the outer diameter Wt of the thin-walled portion 41t, the outer diameter Wh of the through hole 41h, and the inner diameter Wi and outer diameter Wo of the ultrasonic bonding portion 45 preferably satisfy the following formula: (Wt-Wo) / (Wi-Wh)>1.

[0059] Furthermore, the ratio (Wt / Wh) of the outer diameter Wt of the thin-walled portion 41t to the outer diameter Wh of the through-hole 41h is preferably equal to or greater than 2, and more preferably equal to or greater than 3. By making the thin-walled portion 41t larger in this manner, the ultrasonic bonding portion 45 can be formed more stably.

[0060] In the second embodiment, when the through hole 41h is large, for example, 5 mm or more, it is preferable to press the foot 81a of the horn 81 close to the outer periphery of the through hole 41h and the outer periphery of the thin wall portion 41t. In the technology disclosed herein, the through hole 41h can absorb the flow of the material, so that the ultrasonic joint 45 can be formed right up to the edge of the through hole 41h and the thin wall portion 41t. This increases the area of ​​the ultrasonic joint 45, reduces the conduction resistance, and reduces the resistance. In addition, the resistance heat can be kept low, and the thermal effect on the resin member such as the gasket 50 can be reduced.

[0061] From this viewpoint, in the second embodiment, as shown in Fig. 7, in the radial direction of the through hole 41h, the distance D1 between the through hole 41h and the inner peripheral edge of the ultrasonic bonding portion 45 is, for example, preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less. In addition, in the radial direction of the through hole 41h, the ratio (W1 / W2) of the width W1 of the ultrasonic bonding portion 45 to the width W2 of the thin-walled portion 41t is preferably 0.5 or more, and more preferably 0.7 or more. This makes it possible to further reduce the conduction resistance and further reduce the resistance. In addition, it is possible to further suppress the resistance heat generation.

[0062] In the second embodiment, as shown in FIG. 6, the difference (Wi-Wh) between the inner diameter Wi of the ultrasonic bonding portion 45 and the outer diameter Wh of the through hole 41h is preferably 5 mm or less, more preferably 2 mm or less. The ultrasonic bonding portion 45 is preferably separated from the through hole 41h. The difference (Wi-Wh) is preferably 0.1 mm or more. The difference (Wt-Wo) between the outer diameter Wt of the thin-walled portion 41t and the outer diameter Wo of the ultrasonic bonding portion 45 is preferably 5 mm or less, more preferably 2 mm or less. The ultrasonic bonding portion 45 is preferably separated from the outer edge of the thin-walled portion 41t. The difference (Wt-Wo) is preferably 0.1 mm or more. Contrary to the first embodiment, the outer diameter Wt of the thin-walled portion 41t, the outer diameter Wh of the through hole 41h, and the inner diameter Wi and outer diameter Wo of the ultrasonic bonding portion 45 preferably satisfy the following formula: (Wt-Wo) / (Wi-Wh)<1.

[0063] Furthermore, the ratio (Wt / Wh) of the outer diameter Wt of the thin-walled portion 41t to the outer diameter Wh of the through hole 41h is preferably equal to or greater than 2, and more preferably equal to or greater than 3. By enlarging the through hole 41h in this manner, the above-mentioned effects can be exerted to a higher level.

[0064] <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 manufactured by the manufacturing method as described above. The rest of the manufacturing process may be the same as in the past. The electricity storage device 100 can be manufactured by a manufacturing method that includes, for example, 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 performing an attachment step and a case joining step in this order.

[0065] In the 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 body 24 and integrated. The negative terminal 40 and the negative current collecting member 14 are fixed to the lid body 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 the insertion step, a part of the second conductive member 42 of the negative terminal 40 (here, the shaft portion 42s before crimping) is inserted into the hole portion 14h of the negative current collecting member 14. In detail, the shaft portion 42s before crimping of the negative terminal 40 is passed through the tube portion 51 of the gasket 50, the terminal lead-out hole 24h of the lid body 24, the hole portion 60h of the insulator 60, and the hole portion 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.

[0066] 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.

[0067] FIG. 10 is a vertical cross-sectional view showing an example of this step. In FIG. 10, the lid 24, the gasket 50, the insulator 60, and the negative current collecting member 14 are omitted. In some preferred embodiments, as shown in FIG. 10, a crimping device including a punch (press jig) 91 and a die (receiving jig) 92 is first prepared. The die 92 has a flat surface. Next, the negative terminal 40 is placed on the flat surface of the die 92 in a state in which it is turned upside down. As a result, the upper surface 41u of the first conductive member 41 (at least the connection portion 41a) faces the die 92. The thin portion 41t of the first conductive member 41 is floating above the die 92. The second conductive member 42 does not abut against the die 92.

[0068] Next, 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. 10, 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 open and deformed by 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 crimping portion 40c is formed on the negative electrode current collecting member 14, and each component is crimped and fixed.

[0069] In this embodiment, the first conductive member 41 has a second recess 41c on the upper surface 41u. As a result, when the region of the first conductive member 41 that overlaps with the cylindrical portion 42p in the direction in which the cylindrical portion 42p extends (the vertical direction Z in FIG. 10) is defined as the first region A1, and the region in which the ultrasonic bonding portion 45 is formed is defined as the second region A2, the first region A1 protrudes downward (in the direction away from the second conductive member 42) from the second region A2. The downward direction is an example of "a direction perpendicular to the surface to which the terminal of the battery case is attached". Here, the first region A1 is an annular region that overlaps with the cylindrical portion 42p in a plan view. Here, most of the first region A1 abuts against the die 92. The second region A2 is a region on the inner periphery side (closer to the through hole 41h) than the first region A1.

[0070] Since the first region A1 protrudes downward from the second region A2, the die 92 can receive the area directly below the cylindrical portion 42p, making it easier to crimp the cylindrical portion 42p. Also, since the second region A2 is recessed (located above) the first region A1, the compressive force of the crimping process is less likely to be applied to the region where the ultrasonic bonded portion 45 is formed. This reduces the load on the ultrasonic bonded portion 45, and effectively prevents the ultrasonic bonded portion 45 from being damaged.

[0071] 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 method of attaching the positive terminal 30 and the positive current collector 13 may be the same as that of the negative terminal 40 and the negative current collector 14 described above. 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 terminal 40 are electrically connected. Similarly, 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 terminal 30 are electrically connected. As a result, the lid 24, the positive terminal 30, the negative terminal 40, and the electrode body 10 are integrated together.

[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] 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, for example, passenger cars, trucks, etc. 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).

[0074] As shown in Fig. 8, the power storage device 100 can also be suitably used as a battery pack 200 in which a plurality of power storage devices 100 are electrically connected to one another via a bus bar 90. In this case, the electrical connection between the plurality of power storage devices 100 can be achieved by, for example, bridging a flat bus bar 90 between the extensions 41b of the first conductive member 41. The bus bar 90 is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The bus bar 90 and the extensions 41b can be electrically connected to one another by welding such as laser welding.

[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 the above embodiment, the fastening portion 43 is a fitting portion (for example, a press-fit fitting portion). However, this is not limited thereto. The fastening portion 43 may be, for example, a crimping portion.

[0077] (2) For example, in the above embodiment, the first conductive member 41 has the thin-walled portion 41t, and the ultrasonic bonding portion 45 is formed in the thin-walled portion 41t. The ultrasonic bonding portion 45 is provided at a position spaced apart from the through-hole 41h. However, this is not limited to this. The ultrasonic bonding portion 45 may be formed, for example, in a portion other than the thin-walled portion 41t, or may be formed along the outer edge of the through-hole 41h.

[0078] (3) For example, in the above embodiment, the ultrasonic joint 45 is annular in plan view and is continuously formed along the circumferential direction of the through hole 41h. However, this is not limited to this. The ultrasonic joint 45 may be configured to be composed of a plurality of parts, and the plurality of parts may be arranged at positions spaced apart from each other. This ensures a space for the material to escape from the surface to which the pressing load is applied, thereby further suppressing distortion and deformation of the first conductive member 41.

[0079] FIG. 11(A) is a plan view showing a schematic diagram of an ultrasonic bonding unit 145 according to a modified example. The ultrasonic bonding unit 145 includes a plurality of (four here) bonding parts 145a. As shown by the dashed lines in FIG. 11(A), a space is provided between the bonding parts 145a. The bonding parts 145a are arranged at positions spaced apart from each other. The bonding parts 145a have the same shape here. The bonding parts 145a are each arc-shaped or linear here. The bonding parts 145a are preferably arranged in a ring shape with intervals. The bonding parts 145a are preferably arranged at equal intervals, and more preferably arranged point-symmetrically with respect to the center of the through hole 41h. The ultrasonic bonding unit 145 is preferably shaped like a ring with a partial cutout (broken line ring shape). The joints 145a are preferably arranged so as to avoid a straight line passing through the center of the through hole 41h and extending in the vibration direction of the ultrasonic waves (here, the short side direction X to the long side direction Y). Here, the joints 145a are arranged on straight lines extending from the center of the through hole 41h toward the four corners of the rectangular first conductive member 41.

[0080] Such ultrasonic bonding portion 145 can be formed by using, for example, a horn 181 having a plurality of (four here) legs 181a as shown in FIG. 11(B) instead of the horn 81 having the annular leg 81a in the above-mentioned bonding process. The lower surface of the leg 181a has an uneven structure in which protrusions and grooves are alternately formed. In this case, it is preferable that the leg 181a of the horn 181 is brought into contact with the first conductive member 41 so as not to be on a straight line passing through the center of the through hole 41h and extending in the vibration direction of the ultrasonic waves (here, the short side direction X or the long side direction Y). This makes it possible to suppress the first conductive member 41 from being deformed into an unintended shape during ultrasonic bonding, and makes it difficult for the vicinity of the ultrasonic bonding portion 45 to be distorted or raised.

[0081] (4) For example, in the embodiment of FIG. 10 described above, the second conductive member 42 to be plastically deformed does not come into contact with the die (receiving jig) 92 in the crimping process described above. However, this is not limited to this. The second conductive member 42 may come into contact with the die 92. This configuration is particularly suitable when the Vickers hardness of the second conductive member 42 is greater than that of the first conductive member 41.

[0082] FIG. 12(A) is a view corresponding to FIG. 10 according to the first modified example. In this modified example, the die 192 of the crimping device has an outer shape that can be inserted into the through hole 41h of the first conductive member 41. The die 192 is inserted into the through hole 41h of the first conductive member 41 and abuts against the second conductive member 42 (specifically, the flange portion 42f). The die 192 does not abut against the first conductive member 41 here. It is preferable that the die 192 does not abut against the first conductive member 41. However, the die 192 may abut against a part of the first conductive member 41. In this modified example, a part of the second conductive member 42 (the cylindrical portion 42p) is crimped while the die 192 abuts against the second conductive member 42, thereby deforming a part of the second conductive member to form the crimped portion 40c. By using the die 192, the ultrasonic bonded portion 45 and the die 192 do not overlap in the direction in which the compressive force is applied (here, the vertical direction Z). This makes it difficult for a load to be applied to the first conductive member 41 or the ultrasonic bonded portion 45. This effectively prevents unintended distortion or deformation of the first conductive member 41. Also, damage to the ultrasonic bonded portion 45 can be effectively prevented.

[0083] FIG. 12(B) is a view corresponding to FIG. 10 according to the second modified example. In this modified example, the die 292 of the crimping device has a protruding portion 292c that can be inserted into the through hole 41h of the first conductive member 41. The protruding portion 292c is inserted into the through hole 41h of the first conductive member 41 and abuts against the second conductive member 42 (specifically, the flange portion 42f). In addition, a part of the die 292 also abuts against the first conductive member 41. As a result, the second conductive member 42 can bear at least a part of the load, so that the load on the first conductive member 41 or the ultrasonic bonding portion 45 can be reduced compared to the case where all the compressive force is applied to the first conductive member 41. Therefore, it is possible to effectively prevent unintended distortion or deformation from occurring in the first conductive member 41. In addition, it is possible to effectively prevent damage to the ultrasonic bonding portion 45.

[0084] (5) For example, in the above-described embodiment, the cylindrical portion 42p of the negative electrode terminal 40 was deformed and caulked, whereby the negative electrode terminal 40 was fixed on the negative electrode current collector member 14, and the negative electrode terminal 40 and the negative electrode current collector member 14 were electrically connected. However, the present invention is not limited thereto. The method of electrically connecting the negative electrode current collector member 14 and the negative electrode terminal 40 may be, for example, a mechanical fixing other than caulking, a metal bonding typified by welding, or a combination thereof.

[0085] As described above, specific aspects of the technology disclosed herein include those described in the following respective items. Item 1: A method for manufacturing a terminal for a power storage device, comprising: a first conductive member made of a first metal and having a recess and a through hole provided in the 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; an ultrasonic bonding portion where the first conductive member and the second conductive member are ultrasonically bonded around the through hole; and a fastening portion where the first conductive member and the second conductive member are mechanically fastened on an outer peripheral side of the ultrasonic bonding portion. The method includes: an arranging step of arranging a part of the second conductive member in the recess of the first conductive member; and a bonding step of ultrasonically bonding the periphery of the through hole of the first conductive member to the second conductive member after the arranging step. Item 2: A thin-walled portion is provided around the through hole of the first conductive member. The thin-walled portion is thinner than a portion on an outer peripheral side of the thin-walled portion. In the bonding step, the thin-walled portion is ultrasonically bonded to the second conductive member. The manufacturing method according to Item 1. Item 3: In the bonding step, in a radial direction of the through hole, a distance D1 between the through hole and an inner peripheral edge of the ultrasonic bonding portion is made smaller than a distance D2 between an outer peripheral edge of the ultrasonic bonding portion and an outer peripheral edge of the thin-walled portion (D1 < D2). The manufacturing method according to Item 2. Item 4: In the bonding step, in a radial direction of the through hole, ultrasonic bonding is performed such that a ratio (W1 / W2) of a width W1 of the ultrasonic bonding portion to a width W2 of the thin-walled portion is 0.5 or more. The manufacturing method according to Item 2 or Item 3. Item 5: The manufacturing method according to any one of Items 1 to 3, wherein the ultrasonic joint portion is composed of a plurality of parts, and the plurality of parts are arranged at positions separated from each other. Item 6: A method for manufacturing a power storage device including an electrode body having a first electrode and a second electrode, a battery case that houses the electrode body, a terminal attached to the battery case, and a current collecting member that electrically connects the first electrode and the terminal inside the battery case, wherein the terminal includes a first conductive member made of a first metal and having a recess and a through hole provided in the 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, an ultrasonic joint portion where the first conductive member and the second conductive member are ultrasonically joined around the through hole, and a fastening portion where the first conductive member and the second conductive member are mechanically fastened on an outer peripheral side of the ultrasonic joint portion. In the manufacturing of the terminal, the method includes an arranging step of arranging a part of the second conductive member in the recess of the first conductive member, and a joining step of ultrasonically joining the periphery of the through hole of the first conductive member to the second conductive member after the arranging step. Item 7: A thin portion is provided around the through hole of the first conductive member, the thin portion is thinner than a portion on an outer peripheral side of the thin portion, and in the joining step, the thin portion is ultrasonically joined to the second conductive member. The manufacturing method according to Item 6. Item 8: In the joining step, in a radial direction of the through hole, a distance D1 between the through hole and an inner peripheral edge of the ultrasonic joint portion is made smaller than a distance D2 between an outer peripheral edge of the ultrasonic joint portion and an outer peripheral edge of the thin portion (D1 < D2). The manufacturing method according to Item 7. Item 9: The current collecting member has a hole portion, and the method further includes an inserting step of inserting a part of the second conductive member of the terminal into the hole portion of the current collecting member, and a caulking step of caulking a part of the second conductive member of the terminal onto the current collecting member after the inserting step. The manufacturing method according to any one of Items 6 to 8. Item 10: The manufacturing method described in item 9, wherein the second conductive member has a hollow cylindrical portion, and in the crimping process, the cylindrical portion is crimped to the current collecting member, and when a region of the first conductive member that overlaps with the cylindrical portion in a direction in which the cylindrical portion extends is defined as a first region and a region in which the ultrasonic joint is formed is defined as a second region, the first region protrudes in a direction away from the second conductive member more than the second region in a direction perpendicular to a surface of the battery case to which the terminal is attached. Item 11: The manufacturing method according to item 9 or 10, wherein in the crimping process, a receiving jig is inserted into the through hole of the first conductive member so as to be in contact with the second conductive member, and the second conductive member is pressed with a pressing jig to deform a portion of the second conductive member. [Explanation of symbols]

[0086] 10 Electrode body 14 Negative electrode current collector (current collector) 20 Battery case 24 Lid 40 Negative terminal (terminal) 40c Crimping part 41 First conductive member 41d Bottom surface (first surface) 41h through hole 41r 1st recess 41t Thin section 42 Second conductive member 42f Flange 42n Narrowed portion (portion located within the recess) 42p Cylindrical part 43 Fastening Part 45, 145 Ultrasonic joint 100 Electricity storage device

Claims

1. a first conductive member made of a first metal and having a recess on a first surface and a through hole provided in the recess; 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 in which the first conductive member and the second conductive member are ultrasonically bonded to each other around the through hole; 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 method for manufacturing a terminal for an electric storage device comprising: a positioning step of positioning a portion of the second conductive member in the recess of the first conductive member; a joining step of ultrasonically joining a periphery of the through hole of the first conductive member to the second conductive member after the placing step; A method for manufacturing a terminal for an electricity storage device, comprising:

2. a thin-walled portion is provided around the through hole of the first conductive member, The thin-walled portion has a thickness smaller than that of an outer peripheral portion of the thin-walled portion, In the joining step, the thin portion is ultrasonically joined to the second conductive member. The method of claim 1 .

3. In the joining step, a distance D1 between the through hole and an inner peripheral edge of the ultrasonic joining portion in a radial direction of the through hole is set smaller than a distance D2 between an outer peripheral edge of the ultrasonic joining portion and an outer peripheral edge of the thin-walled portion (D1<D2). The method according to claim 2 .

4. In the joining step, ultrasonic joining is performed such that a ratio (W1 / W2) of a width W1 of the ultrasonic joining portion to a width W2 of the thin-walled portion in a radial direction of the through hole is 0.5 or more. The method according to claim 2 or 3.

5. The ultrasonic bonding portion is made up of a plurality of parts, and the plurality of parts are arranged at positions spaced apart from each other. The method according to any one of claims 1 to 3.

6. A method for manufacturing an electricity storage device including: an electrode assembly having a first electrode and a second electrode; a battery case that houses the electrode assembly; a terminal attached to the battery case; and a current collecting member that electrically connects the first electrode and the terminal inside the battery case, the method comprising the steps of: The terminal is a first conductive member made of a first metal and having a recess on a first surface and a through hole provided in the recess; 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 in which the first conductive member and the second conductive member are ultrasonically bonded to each other around the through hole; 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; In the manufacturing of the terminal, a positioning step of positioning a portion of the second conductive member in the recess of the first conductive member; a joining step of ultrasonically joining the periphery of the through hole of the first conductive member to the second conductive member after the placing step; A method for manufacturing an electricity storage device, comprising:

7. a thin-walled portion is provided around the through hole of the first conductive member, The thin-walled portion has a thickness smaller than that of an outer peripheral portion of the thin-walled portion, In the joining step, the thin portion is ultrasonically joined to the second conductive member. A method for manufacturing the electricity storage device according to claim 6.

8. In the joining step, a distance D1 between the through hole and an inner peripheral edge of the ultrasonic joining portion in a radial direction of the through hole is set smaller than a distance D2 between an outer peripheral edge of the ultrasonic joining portion and an outer peripheral edge of the thin-walled portion (D1<D2). A method for manufacturing the electricity storage device according to claim 7.

9. The current collecting member has a hole, 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 step of crimping a portion of the second conductive member of the terminal onto the current collecting member after the insertion step; Further comprising: A method for manufacturing the electricity storage device according to claim 6 .

10. the second conductive member has a hollow tubular portion, In the crimping step, the cylindrical portion is crimped to the current collecting member, When a region of the first conductive member that overlaps with the tubular portion in the extending direction of the tubular portion is defined as a first region, and a region in which the ultrasonic bonding portion is formed is defined as a second region, the first region protrudes in a direction away from the second conductive member more than the second region in a direction perpendicular to a surface of the battery case to which the terminal is attached; A method for manufacturing the electricity storage device according to claim 9.

11. In the crimping step, a receiving jig is inserted into the through hole of the first conductive member so as to be in contact with the second conductive member, and the second conductive member is pressed with a pressing jig to deform a portion of the second conductive member. A method for manufacturing the electricity storage device according to claim 9.

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