Method for manufacturing terminals for energy storage devices and method for manufacturing energy storage devices

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 a power storage device and a method for manufacturing a power storage device.

Background Art

[0002] Conventionally, terminals formed by joining conductive members (a first conductive member and a second conductive member) made of different metals are known (see Patent Documents 1 and 2). For example, Patent Document 1 discloses a method for manufacturing a terminal including an ultrasonic joining step of forming an ultrasonic joining portion by ultrasonically joining a first conductive member and a second conductive member, and a caulking step of caulking (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

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] In ultrasonic joining, a horn is pressed against one of the conductive members, and ultrasonic vibration is applied while applying a pressing load. According to the study by the present inventor, at this time, unintended distortion or deformation may occur in the conductive member against which the horn is pressed. As a result, it may become difficult to perform caulking, or the fastening portion formed earlier may be damaged, and the connection state between the first conductive member and the second conductive member may be unstable.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for manufacturing a terminal for a power storage device and a method for manufacturing a power storage device in which the connection state between a first conductive member and a second conductive member is likely to be stable.

Means for Solving the Problems

[0006] The present invention provides a method for manufacturing a terminal for an energy storage device, comprising: a first conductive member made of a first metal and having a recess on its 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 joint portion around the through hole where the first conductive member and the second conductive member are ultrasonically bonded; and a fastening portion on the outer circumference of the ultrasonic joint portion where the first conductive member and the second conductive member are mechanically fastened. The manufacturing method includes a placement step of placing a portion of the second conductive member in the recess of the first conductive member; and a bonding step, after the placement step, ultrasonically bonding the area around the through hole of the first conductive member with the second conductive member.

[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 explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic perspective view showing an energy storage device according to one embodiment. [Figure 2] Figure 2 is a schematic longitudinal cross-sectional view along the line II-II in Figure 1. [Figure 3] Figure 3 is a schematic, partially enlarged cross-sectional view showing the vicinity of the negative terminal. [Figure 4] Figure 4 is a schematic perspective view showing a negative terminal according to one embodiment. [Figure 5] Figure 5 is a schematic side view of the negative terminal in Figure 4. [Figure 6] Figure 6 is a schematic longitudinal cross-sectional view along the line VI-VI in Figure 4. [Figure 7] Figure 7 is a schematic, enlarged cross-sectional view showing the main parts of Figure 6. [Figure 8] Figure 8 is a schematic perspective view showing a battery pack according to one embodiment. [Figure 9] Figure 9 is a longitudinal cross-sectional view schematically showing an example of the joining process. [Figure 10] Figure 10 is a schematic longitudinal cross-sectional view showing an example of the crimping process. [Figure 11] Figure 11(A) is a schematic plan view showing an ultrasonic joint according to a modified example, and Figure 11(B) is an explanatory diagram illustrating the relationship between the vibration direction and the arrangement of the horns. [Figure 12] Figure 12(A) is a diagram corresponding to Figure 10 relating to the first modified example, and Figure 12(B) is a diagram corresponding to Figure 10 relating to the second modified example. [Modes for carrying out the invention]

[0009] Preferred embodiments of the technology disclosed herein will be described below with reference to the drawings. Matters other than those specifically mentioned herein but necessary for carrying out the present invention (for example, the general configuration and manufacturing process of energy storage devices not characterizing the present invention) can be understood as design matters for those skilled in the art based on the prior art. The technology disclosed herein can be carried out based on the content disclosed herein and common technical knowledge in the art.

[0010] <Energy storage device 100> First, we will describe the energy storage device manufactured by the manufacturing method disclosed herein. In this specification, "energy storage device" is a general term referring to devices that can be repeatedly charged and discharged, and is a concept that encompasses 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] Figure 1 is a perspective view of the energy storage device 100. Figure 2 is a schematic longitudinal cross-sectional view along line II-II in Figure 1. In the following description, the symbols L, R, U, and D in the drawings represent left, right, up, and down, respectively, and the symbols X, Y, and Z in the drawings represent the short side direction, the long side direction perpendicular to the short side direction, and the up and down direction, respectively, of the energy storage device 100. However, these directions are merely for the convenience of explanation and do not limit the installation configuration of the energy storage device 100 in any way.

[0012] As shown in FIG. 2, the power storage device 100 includes an electrode body 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 the same as those of the prior art. The power storage device 100 is preferably a secondary battery, and more preferably a non-aqueous electrolyte secondary battery. The power storage device 100 is a lithium-ion secondary battery herein. Although not shown in the drawings, the power storage device 100 further includes an electrolyte herein. The power storage device 100 is configured such that the electrode body 10 and an electrolyte not shown are housed in the battery case 20.

[0013] The electrode body 10 may be the same as that of the prior art and is not particularly limited. The electrode body 10 has a positive electrode and a negative electrode (not shown). For example, the electrode body 10 is a flat wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are laminated 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 (typically rectangular) positive electrode and a square (typically rectangular) negative electrode are stacked in an insulated state. One of the positive electrode and the negative electrode is an example of the "first electrode", and the other is an example of the "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 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 (for example, a carbon material such as graphite).

[0015] As shown by the slanted lines in FIG. 2, a laminated portion is formed in the central portion of the electrode body 10 in the long side direction Y, where the positive electrode mixture layer and the negative electrode mixture layer are laminated in an insulated state. On the other hand, at the left end portion of the electrode body 10 in the long side direction Y, 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 collecting member 13 is attached to the positive electrode current collector exposed portion. The positive electrode current collecting 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, aluminum alloy, nickel, stainless steel, etc. The positive electrode current collecting member 13 electrically connects the positive electrode and the positive electrode terminal 30 inside the battery case 20.

[0016] Also, at the right end portion of the electrode body 10 in the long side direction Y, a part of the negative electrode current collector 12 where the negative electrode mixture layer is not formed (negative electrode current collector exposed portion) protrudes from the laminated portion. A negative electrode current collecting member 14 is attached to the negative electrode current collector exposed portion. The material (metal type) of the negative electrode current collecting member 14 may be different from that of the positive electrode current collecting member 13. The negative electrode current collecting member 14 may be made of the same metal type as the negative electrode current collector 12, for example, a conductive metal such as copper, copper alloy, nickel, stainless steel, etc. The negative electrode current collecting member 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 the conventional one and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (non-aqueous electrolyte solution) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, etc. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may be in a solid state (solid electrolyte) and integrated with the electrode body 10.

[0018] The battery case 20 is a housing that accommodates the electrode body 10. In this case, the battery case 20 is formed in the shape of a flat, bottomed rectangular parallelepiped (square). However, the shape of the battery case 20 is not limited to a square, 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 there are no particular restrictions. 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 Figure 2 comprises a case body 22 having an opening 22h and a lid (sealing plate) 24 that closes the opening 22h. It is preferable that the battery case 20 comprises a case body 22 and a 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 24 faces the bottom surface 22d of the case body 22. The lid 24 is attached to the case body 22 so as to close the opening 22h of the case body 22. The lid 24 is substantially rectangular in this case. In this specification, "substantially rectangular" is a term that includes not only a perfect rectangle, but also shapes such as those in which the corners connecting the long and short sides of a rectangle are rounded, or shapes with notches in the corners.

[0020] As shown in Figure 1, the positive terminal 30 and the negative terminal 40 protrude from the outside of the battery case 20. Here, the positive terminal 30 and the negative terminal 40 protrude from the same side of the battery case 20 (specifically the lid 24). However, the positive terminal 30 and the negative terminal 40 may protrude from different sides of the battery case 20. The positive terminal 30 and the negative terminal 40 are located at both ends of the long side direction Y of the lid 24, respectively. The positive terminal 30 and / or the negative terminal 40 are examples of "terminals for an energy storage device".

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

[0022] Figure 3 is a schematic, partially enlarged cross-sectional view showing the vicinity of the negative terminal 40. While the terminal structure of the negative terminal 40 will be described in detail below as an example, the terminal structure of the positive terminal 30 may be similar. In that case, the term "negative terminal" can be appropriately replaced with "positive terminal" in the following description.

[0023] As shown in Figure 3, the cover 24 has a terminal lead hole 24h that penetrates in the vertical direction Z. It is preferable that the terminal lead hole 24h is provided in the cover 24. Although not shown in the figure, the terminal lead hole 24h is circular in shape (for example, perfectly circular) in plan view. The terminal lead hole 24h has an inner diameter large enough to allow the shaft portion 42s of the negative electrode terminal 40, which will be described later, to pass through before crimping. The terminal lead hole 24h is formed to be smaller than the flange portion 42f of the negative electrode terminal 40, which will be described later.

[0024] The negative electrode current collector 14 is attached to the exposed portion of the negative electrode current collector 12 and constitutes a conductive path that electrically connects the negative electrode and the negative electrode terminal 40. The negative electrode current collector 14 has a flat plate-shaped portion 14f that extends horizontally along the inner surface of the cover 24. The flat plate-shaped portion 14f is provided with 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 electrode terminal 40, which will be described later, to pass through before crimping. The negative electrode current collector 14 is fixed to the cover 24 together with the negative electrode terminal 40 in an insulated state via the insulator 60 by crimping. The negative electrode current collector 14 is an example of a "current collector".

[0025] The gasket 50 is an insulating member placed between the upper surface (outer surface) of the lid 24 and the negative electrode terminal 40. It is preferable to place an insulating member (e.g., gasket 50) between the battery case 20 (e.g., lid 24) and the negative electrode terminal 40. The gasket 50 in this case has the function of insulating the lid 24 from the negative electrode terminal 40 and closing the terminal lead hole 24h. The gasket 50 is made of an electrically insulating and elastically deformable resin material, such as a fluorinated resin such as perfluoroalkoxy fluororesin (PFA), polyphenylene sulfide resin (PPS), or aliphatic polyamide.

[0026] The gasket 50 has a cylindrical portion 51 and a base portion 52. The cylindrical portion 51 is the part that prevents direct contact between the cover 24 and the shaft portion 42s of the negative electrode terminal 40. The cylindrical portion 51 is hollow and cylindrical in shape. The cylindrical portion 51 has a hole 51h that penetrates in the vertical direction Z. The hole 51h is formed so that the shaft portion 42s of the negative electrode terminal 40 before crimping can be inserted through it. The cylindrical portion 51 is inserted through the terminal lead hole 24h of the cover 24. The base portion 52 is the part that prevents direct contact between the cover 24 and the 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 cylindrical portion 51. The base portion 52 extends horizontally from the upper end of the cylindrical portion 51. The base portion 52 is formed, for example, in an annular shape so as to surround the terminal lead hole 24h of the cover 24. The base portion 52 extends along the upper surface of the cover 24. The base portion 52 is sandwiched between the lower surface 42d of the flange portion 42f of the negative terminal 40 and the upper surface of the cover 24, and is compressed in the vertical direction Z by crimping.

[0027] The insulator 60 is an insulating member positioned between the lower surface (inner surface) of the lid 24 and the negative electrode current collector 14. It is preferable that an insulating member (e.g., the insulator 60) be positioned between the battery case 20 (e.g., the lid 24) and the negative electrode current collector 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 pass through. The insulator 60 is made of a resin material that has resistance to the electrolyte used, electrical insulation properties, and is elastically deformable, such as a fluorinated resin such as perfluoroalkoxy fluoropolymer (PFA) or polyphenylene sulfide resin (PPS). The flat portion of the insulator 60 is sandwiched between the lower surface of the cover 24 and the upper surface of the negative electrode current collector 14, and is compressed in the vertical direction Z by a crimping process.

[0028] <Negative terminal 40> As shown in Figure 3, the negative electrode terminal 40 extends from the inside to the outside of the battery case 20 through the terminal lead-out hole 24h. As will be described later, the negative electrode terminal 40 is constructed by integrating two types of conductive members, namely a first conductive member 41 and a second conductive member 42, with a fastening portion 43 and an ultrasonic bonding portion 45. As shown in Figure 3, the negative electrode terminal 40 is inserted into the terminal lead-out hole 24h of the cover 24 and the hole 14h of the negative electrode current collector 14, and the tip in the insertion direction (a cylindrical portion 42p, which will be described later) 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 cover 24 by crimping and is electrically connected to the negative electrode current collector 14. The crimped portion 40c is cylindrical in this case. 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 collector member 14.

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

[0030] The first conductive member 41 is a member that is placed on the outside of 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, aluminum alloy, nickel, or stainless steel. Preferably, the first conductive member 41 is made of aluminum or an aluminum alloy. Here, the first conductive member 41 is made of aluminum. Preferably, the first conductive member 41 is made of a metal that has a lower Vickers hardness (is softer) than the second conductive member 42. The first conductive member 41 may be the same metal as the positive electrode current collector 13, or an alloy in which the same metal element is the first component (the component with the highest mass ratio; the same applies hereinafter).

[0031] The first conductive member 41 is preferably plate-shaped (more specifically, flat). As shown in Figure 4, in a plan view, the first conductive member 41 is substantially rectangular in shape, having a short side and a long side. As shown in Figure 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 a plan view. The first conductive member 41 has a bottom surface (first surface) 41d and an top surface (second surface) 41u. The bottom surface 41d is the surface facing the battery case 20 (specifically, the lid 24). The bottom surface 41d is the surface in contact with the second conductive member 42. The top surface 41u is the surface away from the battery case 20 and the second conductive member 42.

[0032] As shown in Figures 4 and 5, the first conductive member 41 is a region divided into two parts in the long side direction Y, and has a connecting portion 41a that is electrically connected to the second conductive member 42, and an extended portion 41b that extends from the connecting portion 41a to one side in the long side direction Y (the left side in Figure 4). As shown in Figure 6, the connecting portion 41a here has a first recess 41r, a through hole 41h, a thin-walled portion 41t, and a second recess 41c. However, in other embodiments, the connecting portion 41a may not have the thin-walled portion 41t and / or the second recess 41c.

[0033] The first recess 41r is provided on the lower surface (first surface) 41d, as shown in Figure 6. Although not shown in the illustration, in a plan view, the first recess 41r is ring-shaped (for example, annular) and surrounds the through hole 41h. Although not particularly limited, the outer diameter (diameter in the case of a perfect circle, or the shortest length passing through the center in the case of a non-perfect circle) Wr of the first recess 41r is preferably 6 mm or more. The first recess 41r is formed in a tapered shape that decreases in diameter towards the lower surface 41d of the first conductive member 41 (in other words, as it approaches the second conductive member 42). The flange portion 42f (specifically, the 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".

[0034] As shown in Figure 4, the through-hole 41h is provided within the first recess 41r. The through-hole 41h penetrates the first conductive member 41 in the vertical direction Z. Preferably, the through-hole 41h is 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, the flange portion 42f described later) is exposed through the through-hole 41h. In this case, the through-hole 41h is circular in shape (for example, perfectly circular) in plan view. Although not particularly limited, as shown in Figure 6, the outer diameter Wh of the through-hole 41h (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 typically smaller than the outer diameter Wr of the first recess 41r, preferably 5 to 7 mm. The through-hole 41h is provided on the inner circumference side (center side) of the fastening portion 43 and the ultrasonic bonding portion 45.

[0035] As shown in Figure 4, the thin-walled portion 41t is provided around the through hole 41h. In this case, the thin-walled portion 41t is ring-shaped (for example, annular) in plan view. As shown in Figure 6, the thin-walled portion 41t is formed to be thinner than its outer circumference (for example, the extended 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. In this case, 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. In this case, the thin-walled portion 41t is the 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 opposite to the lower surface 41d on which the first recess 41r is formed (i.e., the upper surface 41u), as in this embodiment. While 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. Here, the outer diameter Wt of the thin-walled portion 41t is smaller than the outer diameter Wr of the first recess 41r. An ultrasonic bonding portion 45 is provided in the thin-walled portion 41t. This allows for more stable formation of the ultrasonic bonding portion 45.

[0036] The second recess 41c is provided on the upper surface (second surface) 41u. As shown in Figure 4, in plan view, the second recess 41c is ring-shaped (e.g., annular) and surrounds the through hole 41h. Although not particularly limited, in plan view, the outer diameter of the second recess 41c (here the same as the outer diameter Wt of the thin-walled portion 41t; 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 Wr of the first recess 41r.

[0037] The extended portion 41b is the part to which a conductive member, the busbar 90 (see Figure 8), is attached when, for example, multiple energy storage devices 100 are electrically connected to each other to create a battery pack 200 (see Figure 8). By having the extended portion 41b, sufficient contact area with the busbar 90 can be secured, thereby improving the 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 by passing 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, copper alloy, nickel, or stainless steel. Preferably, the second conductive member 42 is made of copper or a copper alloy. In this case, the second conductive member 42 is made of copper. Preferably, the second conductive member 42 is 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 the same metal as the negative electrode current collector 14, or an alloy in which the same metallic element is the first component. The second conductive member 42 may have a metal coating portion on part or all of its surface, which is coated with a metal such as Ni.

[0039] The second conductive member 42 has an axis C, as shown in Figures 5 and 6. The second conductive member 42 here 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. Preferably, the second conductive member 42 has a flange portion 42f and a shaft portion 42s connected to one side of the flange portion 42f. Preferably, the flange portion 42f of the second conductive member 42 is located within the first recess 41r of the first conductive member 41.

[0040] The flange portion 42f has a larger outer diameter than the shaft portion 42s. The flange portion 42f is the part that protrudes from the terminal exit hole 24h of the cover 24 to the outside of the battery case 20. As shown in Figure 3, the flange portion 42f has a larger outer diameter than the terminal exit hole 24h of the cover 24. The outer shape of the flange portion 42f is approximately cylindrical in this case. As shown in Figure 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, for example, 2.0 mm. The thickness Tf is here 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 equation: Tf / Tt > 3. This allows for the more stable formation of a high-strength ultrasonic joint 45. 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 where a part of the side surface 42o is constricted.

[0041] The constricted portion 42n is provided continuously or intermittently on a part 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 in the figures, the constricted portion 42n is ring-shaped (for example, annular) in plan view. The constricted portion 42n is formed axially symmetric with respect to the axis C of the flange portion 42f. The constricted portion 42n is formed in an inverse taper shape that widens toward the upper surface 41u (in other words, the further 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 engages with the first recess 41r. The constricted portion 42n is an example of a "part located within a recess".

[0042] As shown in Figure 5, the shaft portion 42s extends downward from the lower end of the flange portion 42f. As shown in Figure 3, it is preferable that the shaft portion 42s is inserted into the terminal lead-out hole 24h of the cover 24 when the negative electrode terminal 40 is attached to the cover 24. As shown in Figures 5 and 6, the shaft portion 42s here has a cylindrical outer shape. The axis of the shaft portion 42s coincides with the axis C of the second conductive member 42. Before crimping, 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 constitutes a cylindrical portion 42p. 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 the part that is expanded by crimping when the negative electrode terminal 40 is attached to the cover 24, and forms a crimped portion 40c. Preferably, the cylindrical portion 42p is electrically connected to the negative electrode current collector 14 inside the battery case 20 by crimping.

[0043] The fastening portion 43 is a connecting portion to which the first conductive member 41 and the second conductive member 42 are mechanically fastened. The fastening portion 43 is provided on the outer circumference side of the through hole 41h in the radial direction, compared to the ultrasonic bonding portion 45. In this case, the fastening portion 43 is configured such that a part of the inner wall of the first recess 41r of the first conductive member 41 fits into the constricted 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 constricted portion 42n of the second conductive member 42. Preferably, the fastening portion 43 is 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 improves the strength of the fastening portion 43. In this case, the fastening portion 43 is formed continuously. In this case, the fastening portion 43 is ring-shaped (for example, annular) in plan view. This increases the strength of the fastening portion 43 and improves the conductivity reliability of the negative electrode terminal 40.

[0044] 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-fit, shrink-fit, crimp, rivet, fold, bolt joint, etc. 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, for example, even if the first conductive member 41 and the second conductive member 42 are made of dissimilar metals. The fastening portion 43 may also be 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 ultrasonic bonding of the first conductive member 41 and the second conductive member 42. The ultrasonic joint 45 is provided around the through hole 41h. In this case, the ultrasonic joint 45 is provided at a position spaced apart from the through hole 41h. In this case, the ultrasonic joint 45 is provided on the thin-walled portion 41t. In this case, the ultrasonic joint 45 is provided at a position spaced apart from the fastening portion 43. In the radial direction of the through hole 41h, the ultrasonic joint 45 is provided on the inner circumference side (towards the center) of the fastening portion 43. The ultrasonic joint 45 may be a joint with relatively lower strength (brittleness) compared to the fastening portion 43. By arranging such an ultrasonic joint 45 on the inner circumference side of the fastening portion 43, the ultrasonic joint 45 can be stably maintained, and the conductivity reliability of the negative electrode terminal 40 can be improved over a long period of time. Furthermore, the ultrasonic bonding portion 45 can be clearly distinguished from, for example, laser welding by the pressure-welding marks of the horn used in the ultrasonic bonding process described later.

[0046] The ultrasonic joint 45 is formed continuously or intermittently in a plan view. Preferably, the ultrasonic joint 45 is formed axially symmetric with respect to the axis C of the second conductive member 42 (e.g., 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 Figure 4. Preferably, the ultrasonic joint 45 is ring-shaped (e.g., annular) in a plan view. This increases the strength of the ultrasonic joint 45 and improves the conductivity reliability of the negative electrode terminal 40.

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

[0048] <Manufacturing method for negative electrode terminal 40> The negative electrode terminal 40 described above can be suitably manufactured by a manufacturing method that includes, for example, a fastening step of mechanically fastening a first conductive member 41 and a 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, a stable ultrasonic bonded portion 45 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 almost simultaneously. Furthermore, the manufacturing method disclosed herein may include other steps at any stage.

[0049] In the fastening process, the flange portion 42f of the first conductive member 41 and the second conductive member 42 are mechanically fastened to form a fastened portion 43. This process includes a placement process in which a part of the second conductive member 42 (for example, a portion including the constricted portion 42n) is placed in the first recess 41r of the first conductive member 41. In other words, it also serves as a placement process. The fastened portion 43 can be formed, for example, by placing 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 along the outer shape of the constricted portion 42n of the second conductive member 42, thereby fixing the inner wall of the first recess 41r with the second conductive member 42. This improves the strength of the fastened portion 43. In some preferred embodiments, the fastened portion 43 is formed by fitting the first recess 41r of the first conductive member 41 and the constricted portion 42n of the second conductive member 42. For example, it 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 improves the workability of the fastening process.

[0050] In the joining process, with a portion of the second conductive member 42 positioned within the first recess 41r of the first conductive member 41, the area around the through hole 41h of the first conductive member 41 is ultrasonically joined to the second conductive member 42 to form an ultrasonic joint 45. Compared to laser welding, for example, ultrasonic joining is less likely to generate brittle intermetallic compounds at the joining interface between the first conductive member 41 and the second conductive member 42. Therefore, a high-strength metallic 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 to the second conductive member 42 (for example, the flange portion 42f). This makes it easier to stably form the ultrasonic joint 45. Also, since less energy is required during joining, the strain and deformation of the first conductive member 41 can be suppressed to a smaller extent.

[0051] Figure 9 is a schematic longitudinal cross-sectional view showing the process. In some preferred embodiments, first, an ultrasonic bonding apparatus is prepared, which includes a horn 81 and an anvil 82 (receiving jig). The horn 81 has an annular foot portion 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 vibrations to the objects to be bonded in a predetermined vibration direction. The anvil 82 is mounted on the press device opposite the horn 81. Here, the anvil 82 has an outer shape that can be accommodated in the cylindrical portion 42p (hollow portion) of the second conductive member 42.

[0052] Next, as shown in Figure 9, the area around the through hole 41h of the first conductive member 41 (in this case, the thin-walled portion 41t) and the portion of the second conductive member 42 located within the first recess 41r of the first conductive member 41 (in this case, 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 in contact with the thin-walled portion 41t of the first conductive member 41, and the anvil 82 is in contact with 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 with the horn 81. As a result, the first conductive member 41, against which the horn 81 is pressed, vibrates in synchronization with the horn 81.

[0053] The indentation load and ultrasonic vibration conditions are design considerations that can be appropriately adjusted depending on, for example, the material and dimensions of the first conductive member 41 to the second conductive member 42, the shape of the horn 81, etc. 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 seconds, and more preferably 0.7 to 1.0 seconds. The vibration direction of the horn 81 may be, for example, the short side direction X, or the long side direction Y.

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

[0055] By positioning a portion of the second conductive member 42 within 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 they are in a terminal state is improved. Furthermore, as in the embodiment, by performing ultrasonic bonding around the through hole 41h, even when a portion of the second conductive member 42 is positioned within the first recess 41r of the first conductive member 41, the area of ​​the first conductive member 41 that is ultrasonically bonded can be smoothly vibrated. As a result, less energy is required, and the first conductive member 41 is less likely to deform. Moreover, even if the first conductive member 41 deforms, the deformation can be absorbed (the flow of material is absorbed) by the through hole 41h, suppressing unintended strain or deformation in the first conductive member 41. Therefore, a stable connection state between the first conductive member 41 and the second conductive member 42 can be suitably achieved. Thus, a more reliable terminal or energy storage device is obtained. Furthermore, when ultrasonically bonding 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 circumference side of the ultrasonic bonding 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, unintended large deformation of the first conductive member 41 can be better suppressed. Further, 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 conduction 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 approaching the ultrasonic bonding portion 45 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 more than 1.

[0058] Furthermore, in the first embodiment, as shown in Figure 6, the difference (Wi-Wh) between the inner diameter Wi of the ultrasonic joint 45 and the outer diameter Wh of the through hole 41h is preferably 5 mm or less, and more preferably 2 mm or less. The ultrasonic joint 45 is preferably separated from the through hole 41h. The above 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 joint 45 are preferably satisfied by the following equation: (Wt-Wo) / (Wi-Wh)>1;

[0059] Furthermore, the ratio of the outer diameter Wt of the thin-walled portion 41t to the outer diameter Wh of the through-hole 41h (Wt / Wh) is preferably 2 or more, and more preferably 3 or more. By making the thin-walled portion 41t larger in this way, 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 portion 81a of the horn 81 against the outer peripheral edge of the through-hole 41h and the outer peripheral edge of the thin-walled portion 41t. In the technology disclosed herein, since the flow of the material can be absorbed in the through-hole 41h, the ultrasonic bonding portion 45 can be formed right up to the edge of the through-hole 41h and the thin-walled portion 41t. This increases the area of ​​the ultrasonic bonding portion 45, reduces the conductivity resistance, and lowers the resistance. Furthermore, resistance heating can be kept low, reducing the thermal impact on resin members such as the gasket 50.

[0061] From this viewpoint, in the second embodiment, as shown in Figure 7, the distance D1 between the through hole 41h and the inner peripheral edge of the ultrasonic bonding portion 45 in the radial direction of the through hole 41h is preferably 5 mm or less, more preferably 3 mm or less, and even more preferably 1 mm or less. Also, 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 conductivity resistance and reduce the resistance. In addition, it is possible to further suppress resistive heat generation.

[0062] Furthermore, in the second embodiment, as shown in Figure 6, the difference (Wi-Wh) between the inner diameter Wi of the ultrasonic joint 45 and the outer diameter Wh of the through hole 41h is preferably 5 mm or less, and more preferably 2 mm or less. The ultrasonic joint 45 is preferably separated from the through hole 41h. The above difference (Wi-Wh) is preferably 0.1 mm or more. Also, the difference (Wt-Wo) between the outer diameter Wt of the thin-walled portion 41t and the outer diameter Wo of the ultrasonic joint 45 is preferably 5 mm or less, and more preferably 2 mm or less. The ultrasonic joint 45 is preferably separated from the outer edge of the thin-walled portion 41t. The above difference (Wt-Wo) is preferably 0.1 mm or more. 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 joint 45 are preferably such that, contrary to the first embodiment, the following equation: (Wt-Wo) / (Wi-Wh)<1; is satisfied.

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

[0064] <Method for manufacturing the energy storage device 100> The energy storage device 100 is characterized by using a positive electrode terminal 30 and / or a negative electrode terminal 40 manufactured by the manufacturing method described above. Other manufacturing processes may be the same as conventional methods. The energy storage device 100 can be manufactured, for example, by preparing the electrode body 10, electrolyte, case body 22, lid 24, positive electrode terminal 30, and negative electrode terminal 40 as described above, and by a manufacturing method that includes an assembly step and a case joining step in this order.

[0065] In the mounting process, the positive terminal 30, the positive current collector 13, the negative terminal 40, and the negative current collector 14 are attached to the cover 24 and integrated. The negative terminal 40 and the negative current collector 14 are fixed to the cover 24 by crimping (riveting), for example, as shown in Figure 3. In some preferred embodiments, this process includes an insertion process and a crimping process in this order. In the insertion process, a portion of the second conductive member 42 of the negative terminal 40 (here, the shaft portion 42s before crimping) is inserted into the hole 14h of the negative current collector 14. Specifically, the shaft portion 42s of the negative terminal 40 before crimping is passed through the cylindrical portion 51 of the gasket 50, the terminal exit hole 24h of the cover 24, the hole 60h of the insulator 60, and the hole 14h of the negative current collector 14 in that order from above the cover 24. This causes the cylindrical portion 42p of the negative electrode terminal 40 to protrude downward from the hole 14h of the negative electrode current collector 14.

[0066] In the crimping process, the second conductive member 42 of the negative electrode terminal 40 is crimped onto the negative electrode current collector 14. Specifically, the cylindrical portion 42p protruding from the hole 14h of the negative electrode current collector 14 is crimped onto the negative electrode current collector 14 so that a compressive force is applied in the vertical direction Z. The crimping process is carried out with a gasket 50 sandwiched between the negative electrode terminal 40 and the cover 24, and an insulator 60 sandwiched between the cover 24 and the negative electrode current collector 14. This forms a crimped portion 40c at the tip of the shaft portion 42s of the negative electrode terminal 40 (the lower end in Figure 3).

[0067] Figure 10 is a schematic longitudinal cross-sectional view showing an example of this process. Note that the cover 24, gasket 50, insulator 60, and negative electrode current collector 14 are not shown in Figure 10. In some preferred embodiments, first, a crimping device is prepared, which includes a punch (press jig) 91 and a die (receiving jig) 92, as shown in Figure 10. The die 92 has a flat surface. Next, the negative electrode terminal 40 is placed on the flat surface of the die 92 in an inverted state. As a result, the upper surface 41u of the first conductive member 41 (at least the connecting portion 41a) faces the die 92. The thin-walled portion 41t of the first conductive member 41 is floating away from the die 92. The second conductive member 42 is not in contact with 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 arrow in Figure 10, a compressive force is applied in the direction in which the cylindrical portion 42p extends (the direction in which the axis C extends, in this case the vertical direction Z), causing the tip of the punch 91 to push and deform the cylindrical portion 42p. As a result, the cylindrical portion 42p is plastically deformed so as to embrace its outer edge. Consequently, a crimped portion 40c is formed on the negative electrode current collector 14, and each component is crimped and fixed in place.

[0069] In this embodiment, the first conductive member 41 has a second recess 41c on its 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 (up and down direction Z in Figure 10) is defined as the first region A1, and the region where the ultrasonic bonding portion 45 is formed is defined as the second region A2, the first region A1 protrudes downward (away from the second conductive member 42) compared to the second region A2. Downward is an example of a direction perpendicular to the surface to which the terminals of the battery case are attached. The first region A1 is, in this case, an annular region that overlaps with the cylindrical portion 42p in a plan view. In this case, most of the first region A1 is in contact with the die 92. The second region A2 is a region on the inner circumference side (closer to the through hole 41h) than the first region A1.

[0070] Because the first region A1 protrudes lower than the second region A2, the die 92 can receive the cylindrical portion 42p directly below it, making it easier to crimp the cylindrical portion 42p. Also, because the second region A2 is recessed (located higher) than the first region A1, the compressive force of the crimping process is less likely to be applied to the area where the ultrasonic joint 45 is formed. Therefore, the load on the ultrasonic joint 45 can be reduced, and damage to the ultrasonic joint 45 can be effectively suppressed.

[0071] Through the crimping process described above, the base 52 of the gasket 50 and the flat portion of the insulator 60 are compressed, and the gasket 50, the cover 24, the insulator 60, and the negative electrode current collector 14 are integrally fixed to the cover 24, and the terminal lead-out hole 24h is sealed. The mounting method for the positive electrode terminal 30 and the positive electrode current collector 13 may be the same as that for the negative electrode terminal 40 and the negative electrode current collector 14 described above. The negative electrode current collector 14 is welded to the exposed negative electrode current collector portion of the negative electrode current collector 12, and the negative electrode of the electrode body 10 and the negative electrode terminal 40 are electrically connected. Similarly, the positive electrode current collector 13 is welded to the exposed positive electrode current collector portion of the positive electrode current collector 11, and the positive electrode of the electrode body 10 and the positive electrode terminal 30 are electrically connected. As a result, the cover 24, the positive electrode terminal 30, the negative electrode terminal 40, and the electrode body 10 are integrated into one unit.

[0072] In the case joining process, the electrode body 10, which is 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. Subsequently, a non-aqueous electrolyte is injected through an injection port (not shown), and the injection port is sealed to seal the energy storage device 100. In this way, the energy storage device 100 can be manufactured.

[0073] The energy storage device 100 can be used for various purposes, but it is particularly suitable for use as a power source (driving power supply) for motors mounted on various types of vehicles, such as passenger cars and trucks. The type of vehicle is not particularly limited, but examples include plug-in hybrid electric vehicles (PHEVs), hybrid electric vehicles (HEVs), and battery electric vehicles (BEVs).

[0074] As shown in Figure 8, the energy storage device 100 can also be suitably used as a battery pack 200 formed by electrically connecting multiple energy storage devices 100 to each other via busbars 90. In this case, the electrical connection between the multiple energy storage devices 100 can be made by, for example, placing a flat busbar 90 between the extended portions 41b of the first conductive member 41. The busbar 90 is made of a conductive metal such as aluminum, aluminum alloy, nickel, or stainless steel. The busbar 90 and the extended portions 41b can be electrically connected by welding, for example, laser welding.

[0075] Although several embodiments of the present invention have been described above, these 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 herein and common technical knowledge in the art. The technologies described in the claims include various modifications and changes to the embodiments illustrated above. For example, it is possible to replace parts of the above embodiments with other variations, and it is also possible to add other variations to the above embodiments. Furthermore, if a technical feature is not described as essential, it may be deleted as appropriate.

[0076] (1) For example, in the embodiment described above, the fastening portion 43 was a fitting portion (for example, a press-fit fitting portion). However, it is not limited to this. The fastening portion 43 may be, for example, a crimping portion.

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

[0078] (3) For example, in the embodiment described above, the ultrasonic joint 45 was annular in plan view and formed continuously along the circumferential direction of the through hole 41h. However, it is not limited to this. The ultrasonic joint 45 may consist of multiple parts, and the multiple parts may be arranged at spaced intervals from each other. This ensures that there is space for the material to escape from the surface on which the pressing load is applied, thereby reducing the strain and deformation of the first conductive member 41.

[0079] Figure 11(A) is a schematic plan view showing an ultrasonic joint 145 according to a modified example. The ultrasonic joint 145 is composed of a plurality of (in this case, four) joint portions 145a. As shown by the dashed lines in Figure 11(A), a space is provided between each of the plurality of joint portions 145a. The plurality of joint portions 145a are arranged at spaced intervals from each other. The plurality of joint portions 145a are identical in shape. The plurality of joint portions 145a are either arc-shaped or linear in shape. It is preferable that the plurality of joint portions 145a are arranged at intervals in an annular shape. It is preferable that the plurality of joint portions 145a are arranged at equal intervals, and more preferably that they are arranged point-symmetrically with respect to the center of the through hole 41h. It is preferable that the ultrasonic joint 145 has an annular shape with a partial notch (dashed annular shape). It is preferable that the multiple joint portions 145a are arranged so as not to lie on a straight line that passes through the center of the through hole 41h and extends in the direction of ultrasonic vibration (here, the short side direction X or the long side direction Y). Here, the multiple joint portions 145a are arranged in straight lines that extend from the center of the through hole 41h toward the four corners of the rectangular first conductive member 41.

[0080] Such an ultrasonic bonding portion 145 can be formed in the bonding process described above by using a horn 181 having multiple (in this case, four) feet 181a instead of a horn 81 having an annular foot portion 81a, as shown in Figure 11(B). The lower surface of the foot portion 181a has an uneven structure in which protrusions and grooves are formed alternately. In this case, it is preferable that the foot portion 181a of the horn 181 contacts the first conductive member 41 such that it passes through the center of the through hole 41h and does not lie on a straight line extending in the direction of ultrasonic vibration (in this case, the short side direction X or the long side direction Y). This suppresses deformation of the first conductive member 41 into an unintended shape during ultrasonic bonding, and makes it less likely for the vicinity of the ultrasonic bonding portion 45 to be distorted or raised.

[0081] (4) For example, in the embodiment shown in Figure 10 above, the second conductive member 42 that is plastically deformed in the crimping process described above was not in contact with the die (receiving jig) 92. However, it is not limited to this. The second conductive member 42 may be in contact with the die 92. Such a configuration can be particularly favored when the Vickers hardness of the second conductive member 42 is greater than that of the first conductive member 41.

[0082] Figure 12(A) is a diagram corresponding to Figure 10 relating 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 is in contact with the second conductive member 42 (specifically the flange portion 42f). In this example, the die 192 is not in contact with the first conductive member 41. It is preferable that the die 192 is not in contact with the first conductive member 41. However, the die 192 may be in contact with a part of the first conductive member 41. In this modified example, with the die 192 in contact with the second conductive member 42, a part of the second conductive member (cylindrical portion 42p) is crimped, thereby deforming a part of the second conductive member and forming a crimped portion 40c. By using the die 192, the ultrasonic joint 45 and the die 192 do not overlap in the direction in which compressive force is applied (in this case, the vertical direction Z). As a result, load is less likely to be applied to the first conductive member 41 or the ultrasonic joint 45. Therefore, unintended strain or deformation of the first conductive member 41 can be effectively suppressed. In addition, damage to the ultrasonic joint 45 can be effectively suppressed.

[0083] Figure 12(B) is a diagram corresponding to Figure 10 relating to a second modified example. In this modified example, the die 292 of the crimping device has a protrusion 292c that can be inserted into the through hole 41h of the first conductive member 41. The protrusion 292c is inserted into the through hole 41h of the first conductive member 41 and is in contact with the second conductive member 42 (specifically the flange portion 42f). In addition, a part of the die 292 is also in contact with the first conductive member 41. As a result, at least a portion of the load can be borne by the second conductive member 42, so the load on the first conductive member 41 or the ultrasonic joint 45 can be reduced compared to the case where all the compressive force is applied to the first conductive member 41. Therefore, unintended strain or deformation of the first conductive member 41 can be effectively suppressed. In addition, damage to the ultrasonic joint 45 can be effectively suppressed.

[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, it is not limited to this. The method of electrically connecting the negative electrode current collector member 14 and the negative electrode terminal 40 may be, for example, mechanical fixing other than caulking, metal bonding typified by welding, or a combination thereof.

[0085] As described above, specific embodiments of the technology disclosed herein include those described in the following 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 the outer peripheral side of the ultrasonic bonding portion, the method including 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 portion is provided around the through hole of the first conductive member, the thin portion is thinner than a portion on the outer peripheral side of the thin portion, and in the bonding step, the thin portion is ultrasonically bonded to the second conductive member. The manufacturing method according to Item 1. Item 3: In the bonding step, in the 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 portion (D1 < D2). The manufacturing method according to Item 2. Item 4: In the bonding step, in the radial direction of the through hole, the ratio (W1 / W2) of the width W1 of the ultrasonic bonding portion to the width W2 of the thin portion is ultrasonically bonded so as to be 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 with 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 with the second conductive member. The manufacturing method according to Item 6. Item 8: In the joining step, a distance D1 between the through hole and an inner peripheral edge of the ultrasonic joint portion in a radial direction of the through hole 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 according to Item 9, wherein the second conductive member has a hollow cylindrical portion, and in the crimping step, the cylindrical portion is crimped to the current collector, and of the first conductive member, the region that overlaps with the cylindrical portion in the direction in which the cylindrical portion extends is defined as the first region, and the region in which the ultrasonic bonding portion is formed is defined as the second region, and in a direction perpendicular to the surface of the battery case to which the terminals are attached, the first region protrudes in a direction away from the second conductive member than the second region. Item 11: The manufacturing method according to item 9 or 10, wherein in the crimping step, a receiving jig is inserted into the through hole of the first conductive member and brought into contact with the second conductive member, and the second conductive member is deformed by pressing it with a press jig. [Explanation of Symbols]

[0086] 10 Electrode body 14. Negative electrode current collector (current collector) 20 Battery Cases 24 Lid 40 Negative terminal (terminal) 40c crimping part 41 First conductive member 41d Bottom surface (first surface) 41h through hole 41r First recess 41t Thin wall part 42 Second conductive member 42f flange section 42n Constricted section (part located within the recess) 42p Cylindrical part 43 Fastening part 45, 145 Ultrasonic joint 100 Energy storage devices

Claims

1. A first conductive member made of a first metal, having a recess on its first surface and a through hole provided within the recess, A second conductive member, which is made of a second metal different from the first metal and has a portion disposed within the recess, Around the through hole, the first conductive member and the second conductive member are ultrasonically bonded to an ultrasonic joint, A fastening portion located on the outer periphery of the ultrasonic bonding portion, where the first conductive member and the second conductive member are mechanically fastened together, A method for manufacturing terminals for an energy storage device, comprising: A placement step of placing a portion of the second conductive member in the recess of the first conductive member, After the arrangement step, a bonding step is performed in which the area around the through hole of the first conductive member is ultrasonically bonded with the second conductive member, Includes, A thin-walled portion is provided around the through-hole of the first conductive member. The thin-walled portion is thinner than the outer peripheral portion of the thin-walled portion. In the bonding process, the thin-walled portion is ultrasonically bonded to the second conductive member, and in the radial direction of the through-hole, the distance D1 between the through-hole and the inner peripheral edge of the ultrasonic bonding portion is made smaller than the distance D2 between the outer peripheral edge of the ultrasonic bonding portion and the outer peripheral edge of the thin-walled portion (D1 < D2). A method for manufacturing terminals for energy storage devices.

2. In the bonding process, ultrasonic bonding is performed such that the ratio of the width W1 of the ultrasonic bonding portion to the width W2 of the thin-walled portion (W1 / W2) in the radial direction of the through hole is 0.5 or more. A method for manufacturing a terminal according to claim 1.

3. The ultrasonic bonding portion consists of multiple parts, and each of the multiple parts is arranged at a distance from each other. A method for manufacturing a terminal according to claim 1 or 2.

4. A first conductive member made of a first metal, having a recess on its first surface and a through hole provided within the recess, A second conductive member, which is made of a second metal different from the first metal and has a portion disposed within the recess, Around the through hole, the first conductive member and the second conductive member are ultrasonically bonded to an ultrasonic joint, A fastening portion located on the outer periphery of the ultrasonic bonding portion, where the first conductive member and the second conductive member are mechanically fastened together, A method for manufacturing terminals for an energy storage device, comprising: A placement step of placing a portion of the second conductive member in the recess of the first conductive member, After the arrangement step, a bonding step is performed in which the area around the through hole of the first conductive member is ultrasonically bonded with the second conductive member, Includes, A thin-walled portion is provided around the through-hole of the first conductive member. The thin-walled portion is thinner than the outer peripheral portion of the thin-walled portion. The ratio of the outer diameter Wt of the thin-walled portion to the outer diameter Wh of the through hole (Wt / Wh) is 3 or more. In the bonding process, the thin-walled portion is ultrasonically bonded to the second conductive member. A method for manufacturing terminals for energy storage devices.

5. A first conductive member made of a first metal, having a recess on its first surface and a through hole provided within the recess, A second conductive member, which is made of a second metal different from the first metal and has a portion disposed within the recess, Around the through hole, the first conductive member and the second conductive member are ultrasonically bonded to an ultrasonic joint, A fastening portion located on the outer periphery of the ultrasonic bonding portion, where the first conductive member and the second conductive member are mechanically fastened together, A method for manufacturing terminals for an energy storage device, comprising: A placement step of placing a portion of the second conductive member in the recess of the first conductive member, After the arrangement step, a bonding step is performed in which the area around the through hole of the first conductive member is ultrasonically bonded with the second conductive member, Includes, The ultrasonic bonding portion consists of multiple parts, In the joining process, the plurality of parts are arranged at spaced-apart positions, and the plurality of parts are arranged so as not to pass through the center of the through hole and to avoid a straight line extending in the direction of ultrasonic vibration. A method for manufacturing terminals for energy storage devices.

6. A method for manufacturing an energy storage device comprising: an electrode body having a first electrode and a second electrode; a battery case housing the electrode body; a terminal attached to the battery case; and a current collector member that electrically connects the first electrode and the terminal inside the battery case, The aforementioned terminal is, A first conductive member made of a first metal, having a recess on its first surface and a through hole provided within the recess, A second conductive member, which is made of a second metal different from the first metal and has a portion disposed within the recess, Around the through hole, the first conductive member and the second conductive member are ultrasonically bonded to an ultrasonic joint, A fastening portion located on the outer periphery of the ultrasonic bonding portion, where the first conductive member and the second conductive member are mechanically fastened together, The terminal is equipped with, A placement step of placing a portion of the second conductive member in the recess of the first conductive member, After the arrangement step, a bonding step is performed in which the area around the through hole of the first conductive member is ultrasonically bonded with the second conductive member, Includes, A thin-walled portion is provided around the through-hole of the first conductive member. The thin-walled portion is thinner than the outer peripheral portion of the thin-walled portion. In the bonding process, the thin-walled portion is ultrasonically bonded to the second conductive member, and in the radial direction of the through-hole, the distance D1 between the through-hole and the inner peripheral edge of the ultrasonic bonding portion is made smaller than the distance D2 between the outer peripheral edge of the ultrasonic bonding portion and the outer peripheral edge of the thin-walled portion (D1 < D2). A method for manufacturing an energy storage device.

7. The current collector member has a hole, An insertion step of inserting a part of the second conductive member of the terminal into the hole of the current collector, After the insertion step, a crimping step is performed in which a part of the second conductive member of the terminal is crimped onto the current collector member, Further including, A method for manufacturing an energy storage device according to claim 6.

8. The second conductive member has a hollow cylindrical portion, In the crimping process, the cylindrical portion is crimped to the current collector member. When the region of the first conductive member that overlaps with the cylindrical portion in the direction in which the cylindrical portion extends is defined as the first region, and the region in which the ultrasonic bonding portion is formed is defined as the second region, In a direction perpendicular to the surface of the battery case to which the terminals are attached, the first region protrudes in a direction away from the second conductive member than the second region. A method for manufacturing an energy storage device according to claim 7.

9. In the crimping process, the receiving jig is inserted into the through hole of the first conductive member and brought into contact with the second conductive member, and the second conductive member is pressed with a press jig to deform a part of the second conductive member. A method for manufacturing an energy storage device according to claim 7 or 8.

10. A method for manufacturing an energy storage device comprising: an electrode body having a first electrode and a second electrode; a battery case housing the electrode body; a terminal attached to the battery case; and a current collector member that electrically connects the first electrode and the terminal inside the battery case, The aforementioned terminal is, A first conductive member made of a first metal, having a recess on its first surface and a through hole provided within the recess, A second conductive member, which is made of a second metal different from the first metal and has a portion disposed within the recess, Around the through hole, the first conductive member and the second conductive member are ultrasonically bonded to an ultrasonic joint, A fastening portion located on the outer periphery of the ultrasonic bonding portion, where the first conductive member and the second conductive member are mechanically fastened together, The terminal is equipped with, A placement step of placing a portion of the second conductive member in the recess of the first conductive member, After the arrangement step, a bonding step is performed in which the area around the through hole of the first conductive member is ultrasonically bonded with the second conductive member, Includes, The current collector member has a hole, An insertion step of inserting a part of the second conductive member of the terminal into the hole of the current collector, After the insertion step, a crimping step is performed in which a part of the second conductive member of the terminal is crimped onto the current collector member, It further includes, The second conductive member has a hollow cylindrical portion, In the crimping process, the cylindrical portion is crimped to the current collector member. When the region of the first conductive member that overlaps with the cylindrical portion in the direction in which the cylindrical portion extends is defined as the first region, and the region in which the ultrasonic bonding portion is formed is defined as the second region, In a direction perpendicular to the surface of the battery case to which the terminals are attached, the first region protrudes in a direction away from the second conductive member than the second region. A method for manufacturing an energy storage device.

11. In the crimping process, the receiving jig is brought into contact with the first region. A method for manufacturing an energy storage device according to claim 10.

12. A method for manufacturing an energy storage device comprising: an electrode body having a first electrode and a second electrode; a battery case housing the electrode body; a terminal attached to the battery case; and a current collector member that electrically connects the first electrode and the terminal inside the battery case, The aforementioned terminal is, A first conductive member made of a first metal, having a recess on its first surface and a through hole provided within the recess, A second conductive member, which is made of a second metal different from the first metal and has a portion disposed within the recess, Around the through hole, the first conductive member and the second conductive member are ultrasonically bonded to an ultrasonic joint, A fastening portion located on the outer periphery of the ultrasonic bonding portion, where the first conductive member and the second conductive member are mechanically fastened together, The terminal is equipped with, A placement step of placing a portion of the second conductive member in the recess of the first conductive member, After the arrangement step, a bonding step is performed in which the area around the through hole of the first conductive member is ultrasonically bonded with the second conductive member, Includes, The current collector member has a hole, An insertion step of inserting a part of the second conductive member of the terminal into the hole of the current collector, After the insertion step, a crimping step is performed in which a part of the second conductive member of the terminal is crimped onto the current collector member, It further includes, In the crimping process, the receiving jig is inserted into the through hole of the first conductive member and brought into contact with the second conductive member, and the second conductive member is pressed with a press jig to deform a part of the second conductive member. A method for manufacturing an energy storage device.

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