Terminal for power storage device and power storage device

Abstract

To improve the reliability of fastening portions of terminals for a power storage device.SOLUTION: A negative electrode terminal 40 includes a first conductive member 41 and a second conductive member 42. The first conductive member 41 has a first recess 41R at a first surface 41a. The second conductive member 42 includes a flange portion 42f and a shaft portion 42s. At least a portion of the flange portion 42f is disposed within the first recess 41R. The first conductive member 41 includes a metal joint portion 45 that is metal-joined to the flange portion 42f. The flange portion 42f includes a large diameter portion 42fa and a small diameter portion 42fb. The outer peripheral side surface of the small diameter portion 42fb has a fastening portion 43 that is mechanically fastened to the inner surface of the first recess 41R. A seal portion 44 is provided at an end C1 of a contact region C between the first conductive member 41 and the flange portion 42f of the second conductive member 42.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2022-049729 discloses a terminal including a plate-shaped first conductive member and a second conductive member having a flange portion. The first conductive member and the flange portion of the second conductive member are mechanically fastened. The first conductive member and the flange portion of the second conductive member are metal-jointed at a position away from the fastening portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-049729 Summary of the Invention [Problem to be solved by the invention]

[0004] A terminal for an electric storage device, which is formed by mechanically fastening different metals to each other, is required to have a fastening portion with higher reliability. [Means for solving the problem]

[0005] The terminal for an electric storage device disclosed herein includes a first conductive member made of a first metal and a second conductive member made of a second metal different from the first metal. The first conductive member has a first recess on a first surface. The second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion. At least a portion of the flange portion is disposed within the first recess. The flange portion has a large diameter portion and a small diameter portion. The small diameter portion is located farther from the shaft portion than the large diameter portion. The terminal for an electric storage device has a fastening portion where an outer peripheral side surface of the small diameter portion is mechanically fastened to the inner surface of the first recess. A seal portion is provided at the end of the abutment area between the first conductive member and the flange portion of the second conductive member. This terminal for an electric storage device has high reliability of the fastening portion between the first conductive member and the second conductive member. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a perspective view of the electricity storage device 100. As shown in FIG. [Figure 2] FIG. 2 is a schematic vertical cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 3 is a cross-sectional view showing the negative electrode terminal 40 attached to the sealing plate 24. As shown in FIG. [Figure 4] FIG. 4 is a perspective view showing the battery pack 200. As shown in FIG. [Figure 5] FIG. 5 is a schematic diagram of the external conductive member 48. [Figure 6] FIG. 6 is a cross-sectional view of the negative electrode terminal 40. [Figure 7] FIG. 7 is a cross-sectional view of a negative electrode terminal 40A according to another embodiment. [Figure 8] FIG. 8 is a cross-sectional view of a negative electrode terminal 40B according to another embodiment. [Figure 9] FIG. 9 is a cross-sectional view of a negative electrode terminal 40C according to another embodiment. [Figure 10] FIG. 10 is a perspective view of the second conductive member 42. As shown in FIG. [Figure 11] FIG. 11 is a schematic diagram of the protrusion 42p. [Figure 12] FIG. 12 is a schematic diagram of a protrusion 42p according to another embodiment. [Figure 13] FIG. 13 is a cross-sectional view of a negative electrode terminal 40D according to another embodiment. [Figure 14] FIG. 14 is a cross-sectional view of a negative electrode terminal 40E according to another embodiment. [Figure 15] FIG. 15 is a cross-sectional view of a negative electrode terminal 40F according to another embodiment. [Figure 16] FIG. 16 is a cross-sectional view of a negative electrode terminal 40G according to another embodiment. [Figure 17] FIG. 17 is a cross-sectional view of a negative electrode terminal 40H according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] An embodiment of the technology disclosed herein will be described below with reference to the drawings. The embodiments described herein are, of course, not intended to limit the present invention. The drawings are schematic and do not necessarily reflect the actual product. Furthermore, identical reference numerals are used to designate components and parts that perform the same function, and redundant descriptions will be omitted where appropriate. In the following description, the reference numerals L, R, F, Rr, U, and D in the drawings represent left, right, front, rear, top, and bottom, and the reference numerals X, Y, and Z in the drawings represent the long side direction, short side direction, and height direction of the power storage device, respectively. However, these directions are merely used for convenience of description and do not in any way limit the installation form of the power storage device.

[0008] In this specification, the term "electricity storage device" refers to a general electricity storage device capable of extracting electrical energy. Electricity storage devices include secondary batteries that can be repeatedly charged and discharged by the movement of charge carriers between a pair of electrodes (positive and negative electrodes) via an electrolyte, as well as capacitors such as electric double layer capacitors. Hereinafter, an embodiment of a method for manufacturing an electricity storage device will be described in which a lithium ion secondary battery is used.

[0009] <Electricity storage device 100> FIG. 1 is a perspective view of an energy storage device 100. FIG. 2 is a schematic longitudinal cross-sectional view taken along line II-II in FIG. 1. In FIG. 2, the gasket 50 and the insulator 60 are omitted. FIG. 3 is a cross-sectional view showing a negative electrode terminal 40 attached to a sealing plate 24. FIG. 4 is a perspective view showing a battery pack 200. FIG. 4 illustrates a configuration in which a plurality of energy storage devices 100 disclosed herein are connected in series via bus bars 90, each serving as a single cell.

[0010] As shown in FIG. 2 , the energy storage device 100 includes an electrode assembly 10, a case 20, a positive electrode terminal 30, and a negative electrode terminal 40. The energy storage device 100 may include an external conductive member 48. The energy storage device 100 is characterized by including the positive electrode terminal 30 and / or the negative electrode terminal 40 disclosed herein, and other configurations may be similar to conventional devices. The energy storage device 100 is preferably a secondary battery, more preferably a non-aqueous electrolyte secondary battery. The energy storage device 100 is preferably a prismatic secondary battery. Here, the energy storage device 100 is a lithium ion secondary battery. Although not shown, the energy storage device 100 further includes an electrolyte. The energy storage device 100 is configured by housing the electrode assembly 10 and an electrolyte (not shown) in a case 20.

[0011] The electrode assembly 10 may be the same as a conventional one and is not particularly limited. The electrode assembly 10 includes a positive electrode and a negative electrode (not shown). The electrode assembly 10 is, for example, a flat wound electrode assembly in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state via a strip-shaped separator and wound around a winding axis. However, in other embodiments, the electrode assembly 10 may be a laminated electrode assembly in which a square-shaped (typically rectangular) positive electrode and a square-shaped (typically rectangular) negative electrode are stacked in an insulated state.

[0012] The positive electrode has a positive electrode current collector 11 and a positive electrode mixture layer (not shown) fixed on the positive electrode current collector 11. The positive electrode current collector 11 is made of a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode mixture layer contains a positive electrode active material (e.g., a lithium transition metal composite oxide). The negative electrode has a negative electrode current collector 12 and a negative electrode mixture layer (not shown) fixed on the negative electrode current collector 12. The negative electrode current collector is made of a conductive metal such as copper, a copper alloy, nickel, or stainless steel. The negative electrode mixture layer contains a negative electrode active material (e.g., a carbon material such as graphite).

[0013] As shown by the diagonal lines in FIG. 2 , a laminated portion is formed in the center of the electrode body 10 in the long side direction X, where a positive electrode mixture layer and a negative electrode mixture layer are laminated in an insulated state. Meanwhile, at the left end of the electrode body 10 in the long side direction X, a portion of the positive electrode current collector 11 where no positive electrode mixture layer is formed (exposed positive electrode current collector portion) protrudes from the laminated portion. A positive electrode current collector member 13 is attached to the exposed positive electrode current collector portion. The positive electrode current collector member 13 may be made of the same metal material as the positive electrode current collector 11, such as a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The positive electrode current collector member 13 is disposed within the case 20. The positive electrode current collector member 13 electrically connects the positive electrode to the positive electrode terminal 30.

[0014] Furthermore, at the right end of the electrode assembly 10 in the long side direction X, a portion of the negative electrode current collector 12 on which the negative electrode mixture layer is not formed (negative electrode current collector exposed portion) protrudes from the laminated portion. A negative electrode current collector 14 is attached to the negative electrode current collector exposed portion. The 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 is disposed within the case 20. The negative electrode current collector 14 electrically connects the negative electrode and the negative electrode terminal 40. The negative electrode current collector 14 electrically connects the negative electrode and the negative electrode terminal 40 inside the case 20.

[0015] The electrolyte may be the same as conventional ones and is not particularly limited. The electrolyte is, for example, a non-aqueous liquid electrolyte (nonaqueous electrolytic solution) containing a non-aqueous solvent and a supporting salt. The non-aqueous solvent contains, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting salt is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte may be a solid (solid electrolyte) and integrated with the electrode assembly 10.

[0016] The case 20 is a housing that houses the electrode assembly 10. Here, the case 20 is formed in a flat, bottomed rectangular parallelepiped (rectangular) shape. However, the shape of the case 20 is not limited to a rectangular shape and may be any shape, such as a cylindrical shape. The material of the case 20 is not particularly limited and may be the same as that conventionally used. The case 20 is made of a lightweight metal material with good thermal conductivity, such as aluminum, an aluminum alloy, or stainless steel. The case 20 includes an exterior body 22 having an opening 22h and a sealing plate 24 that closes the opening 22h. The case 20 preferably includes the exterior body 22 and the sealing plate 24. The case 20 is integrated by joining (e.g., welding) the sealing plate 24 to the periphery of the opening 22h of the exterior body 22. The case 20 is hermetically sealed (sealed).

[0017] Exterior body 22 has a bottom surface 22d. Sealing plate 24 faces bottom surface 22d of exterior body 22. Sealing plate 24 is attached to exterior body 22 so as to close opening 22h of exterior body 22. Here, sealing plate 24 has a substantially rectangular shape. Note that in this specification, the term "substantially rectangular shape" encompasses not only a perfect rectangular shape (rectangular shape), but also shapes in which, for example, corners connecting the long and short sides of a rectangle are rounded, or shapes in which the corners have cutouts.

[0018] The positive electrode terminal 30 and the negative electrode terminal 40 protrude to the outside of the case 20. Here, the positive electrode terminal 30 and the negative electrode terminal 40 each protrude from the same surface of the case 20 (specifically, the sealing plate 24). However, the positive electrode terminal 30 and the negative electrode terminal 40 may each protrude from different surfaces of the case 20. The positive electrode terminal 30 and the negative electrode terminal 40 are respectively disposed at both end portions of the sealing plate 24 in the long side direction X. The positive electrode terminal 30 and / or the negative electrode terminal 40 are an example of a "terminal for a power storage device."

[0019] As shown in FIG. 2, the positive electrode terminal 30 is electrically connected to the positive electrode of the electrode assembly 10 via a positive electrode current collector 13 inside the case 20. The negative electrode terminal 40 is electrically connected to the negative electrode of the electrode assembly 10 via a negative electrode current collector 14 inside the case 20. The positive electrode terminal 30 and the negative electrode terminal 40 are each attached to the case 20 (specifically, the sealing plate 24). The positive electrode terminal 30 and the negative electrode terminal 40 are preferably fixed to the case 20 (specifically, the sealing plate 24). The positive electrode terminal 30 and the negative electrode terminal 40 are each insulated from the sealing plate 24 via a gasket 50 (see FIG. 3) and an insulator 60 (see FIG. 3).

[0020] The configurations of the positive electrode terminal 30 and the negative electrode terminal 40 of the energy storage device 100 will be described in detail below, taking the terminal structure on the negative electrode terminal 40 side as an example. The terminal structure described below is preferably provided on the negative electrode terminal 40 side. Note that the terminal structure described below may be provided on the positive electrode terminal 30 side, or may be provided on both the positive electrode terminal 30 side and the negative electrode terminal 40 side. In that case, in the following description, "negative electrode" can be read as "positive electrode" as appropriate.

[0021] As shown in FIG. 3, the sealing plate 24 is formed with a terminal mounting hole 24h penetrating in the up-down direction Z. The terminal mounting hole 24h is provided in the case 20 (in this embodiment, the sealing plate 24). It is preferable that the negative electrode terminal 40 is inserted into the terminal mounting hole 24h. Although not shown, the terminal mounting hole 24h here has a circular shape (for example, a perfect circle) in a plan view. The terminal mounting hole 24h has an inner diameter large enough to allow a crimped portion 40c of the negative electrode terminal 40, described later, to be inserted therethrough before crimping. The terminal mounting hole 24h is formed smaller than a flange portion 42f of the negative electrode terminal 40, described later.

[0022] The negative current collector 14 is attached to the exposed portion of the negative current collector 12 and forms a conductive path electrically connecting the negative electrode and the negative terminal 40. The negative current collector 14 has a flat portion 14f that extends horizontally along the inner surface of the sealing plate 24. The flat portion 14f has an opening 14h at a position corresponding to the terminal mounting hole 24h. The opening 14h has an inner diameter large enough to allow the crimped portion 40c of the negative terminal 40 (described later) to be inserted therethrough before crimping. The negative current collector 14 is fixed to the sealing plate 24 together with the negative terminal 40 by crimping. A resin insulating member is preferably disposed between the case 20 (in this embodiment, the sealing plate 24) and the negative current collector 14. In this embodiment, the negative current collector 14 is fixed to the sealing plate 24 together with the negative terminal 40 in a state of being insulated via an insulator 60.

[0023] The gasket 50 is an insulating member disposed between the upper surface (outer surface) of the sealing plate 24 and the negative electrode terminal 40. An insulating member (e.g., the gasket 50) is preferably disposed between the case 20 (e.g., the sealing plate 24) and the negative electrode terminal 40. Here, the gasket 50 serves to insulate the sealing plate 24 from the negative electrode terminal 40 and also to close the terminal mounting hole 24h. The gasket 50 is made of an electrically insulating and elastically deformable resin material, for example, a fluorinated resin such as perfluoroalkoxy fluorine resin (PFA), polyphenylene sulfide resin (PPS), aliphatic polyamide, or the like.

[0024] The gasket 50 has a tubular portion 51 and a base portion 52. The tubular portion 51 is a portion that prevents direct contact between the sealing plate 24 and the crimped portion 40c of the negative electrode terminal 40. The tubular portion 51 has a hollow cylindrical shape. The tubular portion 51 has a hole portion 51h that penetrates in the vertical direction Z. The hole portion 51h is formed so that the crimped portion 40c of the negative electrode terminal 40 can be inserted therethrough before crimping. The tubular portion 51 is inserted into the terminal mounting hole 24h of the sealing plate 24. The base portion 52 is a portion that prevents direct contact between the sealing plate 24 and a flange portion 42f of the negative electrode terminal 40, which will be described later. The base portion 52 is connected to the upper end of the tubular portion 51. The base portion 52 extends horizontally from the upper end of the tubular portion 51. The base 52 is formed, for example, in a circular ring shape so as to surround the terminal mounting hole 24h of the sealing plate 24. The base 52 extends along the upper surface of the sealing plate 24. The base 52 is sandwiched between the lower surface 42d of the flange portion 42f of the negative electrode terminal 40 and the upper surface of the sealing plate 24, and is compressed in the vertical direction Z by crimping.

[0025] The insulator 60 is an insulating member disposed between the lower surface (inner surface) of the sealing plate 24 and the negative electrode current collecting member 14. An insulating member (e.g., the insulator 60) is preferably disposed between the case 20 (e.g., the sealing plate 24) and the negative electrode current collecting member 14. The insulator 60 has a flat plate-shaped portion that extends horizontally along the inner surface of the sealing plate 24. A hole 60h is formed in this flat plate-shaped portion at a position corresponding to the terminal mounting hole 24h. The hole 60h has an inner diameter large enough to allow the shaft portion 42s of the negative electrode terminal 40 to be inserted therethrough. The insulator 60 is made of an elastically deformable resin material that is resistant to the electrolyte used, has electrical insulating properties, and is, for example, a fluorinated resin such as perfluoroalkoxy fluororesin (PFA) or polyphenylene sulfide resin (PPS). The flat plate portion of the insulator 60 is sandwiched between the lower surface of the sealing plate 24 and the upper surface of the negative electrode current collecting member 14, and is compressed in the vertical direction Z by caulking.

[0026] <Negative terminal 40> The negative electrode terminal 40 includes a first conductive member 41 and a second conductive member 42. As shown in FIG. 3 , the negative electrode terminal 40 extends from the inside to the outside of the case 20 through the terminal mounting hole 24h. The negative electrode terminal 40 may further include an external conductive member 48 connected to the first conductive member 41 outside the case 20.

[0027] The negative electrode terminal 40 has two types of conductive members, that is, a first conductive member 41 and a second conductive member 42, which are electrically connected to each other via a metal joint 45.

[0028] The negative electrode terminal 40 is inserted into the terminal mounting hole 24h of the sealing plate 24 and the opening 14h of the negative electrode current collector 14, and its leading end in the insertion direction is crimped onto the negative electrode current collector 14. Specifically, the crimped portion is crimped to the peripheral portion surrounding the opening 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 sealing plate 24 and electrically connected to the negative electrode current collector 14 by crimping. In this example, the crimped portion 40c is cylindrical. However, the shape of the crimped portion 40c is not limited to a cylindrical shape and may be any shape, such as a columnar shape. It is preferable that the crimped portion 40c be welded to the negative electrode current collector 14. The first conductive member 41 and the second conductive member 42 constituting the negative electrode terminal 40 will be described below.

[0029] <First conductive member 41> The first conductive member 41 is a member disposed outside the case 20. The first conductive member 41 is made of a first metal. The first metal is a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The first metal side is preferably aluminum or an aluminum alloy. Here, the first conductive member 41 is made of aluminum. The first conductive member 41 is preferably 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 made of the same metal as the positive electrode current collecting member 13, or an alloy that has the same metal element as the first component (the component with the highest mass ratio; the same applies below).

[0030] The first conductive member 41 preferably has a diameter greater than its thickness. In this embodiment, the first conductive member 41 is plate-shaped (more specifically, flat plate-shaped). The first conductive member 41 is preferably substantially disk-shaped in plan view. The first conductive member 41 has a first surface 41a and a second surface 41b. The first surface 41a is a surface that is joined to the second conductive member 42.

[0031] The first conductive member 41 has a first recess 41R on the first surface 41a. The first recess 41R is formed in approximately the center of the first surface 41a of the first conductive member 41. The first recess 41R is a portion where at least a portion of the flange portion 42f is disposed. The first recess 41R preferably has a portion of the flange portion 42f, described later, where the small diameter portion 42fb is disposed, and a portion where the large diameter portion 42fa is disposed. The first recess 41R preferably includes at least a portion where the small diameter portion 42fb is disposed. In this embodiment, the first recess 41R has a portion of the large diameter portion 42fa and the small diameter portion 42fb disposed therein. The first recess 41R has a shape corresponding to the small diameter portion 42fb and the large diameter portion 42fa. Therefore, a portion of the outer peripheral side surface of the large diameter portion 42fa contacts the inner peripheral side surface of the first recess 41R of the first conductive member 41. In this way, it is preferable that the inner peripheral side surface of the first recess 41R of the first conductive member 41 be disposed radially outward of the outer peripheral side surface of the large diameter portion 42fa of the second conductive member 42.

[0032] The shape of the first recess 41R is not particularly limited. In this embodiment, the first recess 41R has a first bottom surface 41R1 and a second bottom surface 41R2, which have different depths. The first bottom surface 41R1 is located deeper than the second bottom surface 41R2. Here, the first bottom surface 41R1 is located at the deepest position of the first recess 41R. In other words, the first bottom surface 41R1 is located at the position farthest from the opening 41R3 of the first recess 41R. The first bottom surface 41R1 is a substantially circular surface and has a shape corresponding to the upper surface 42u1 of the small diameter portion 42fb of the flange portion 42f of the second conductive member 42. The second bottom surface 41R2 is located between the first bottom surface 41R1 and the opening 41R3. The second bottom surface 41R2 is a substantially annular surface and has a shape corresponding to the upper surface 42u of the large diameter portion 42fa of the flange portion 42f. Here, the upper surfaces 42u, 42u1 refer to the surfaces that contact the first conductive member 41 and are the surfaces opposite the lower surface 42d from which the shaft portion 42s extends.

[0033] The first recess 41R is recessed in a generally circular shape with a generally constant diameter from the opening 41R3 toward the second bottom surface 41R2. The large-diameter portion 42fa has an outer diameter corresponding to the inner diameter of the first recess 41R on the side closer to the opening 41R3 than the second bottom surface 41R2. In other words, the large-diameter portion 42fa is a generally disk-shaped portion having a diameter substantially equal to the inner diameter of the first recess 41R from the opening 41R3 to the first bottom surface 41R1. In this embodiment, the thickness of the large-diameter portion 42fa is set slightly larger than the length from the second bottom surface 41R2 to the opening 41R3. Therefore, the large-diameter portion 42fa protrudes slightly downward from the first surface 41a of the first conductive member 41. The dimensional relationship between the large-diameter portion 42fa and the first recess 41R in the height direction is not limited to this dimensional relationship. In view of providing a sealing portion 44 described below, it is preferable that the lower surface 42d of the large diameter portion 42fa does not protrude too much from the first surface 41a of the first conductive member 41. The dimension by which the first surface 41a of the first conductive member 41 protrudes from the lower surface 42d of the large diameter portion 42fa may be, for example, 1 mm or less, and preferably 0.5 mm or less. For example, the first surface 41a of the first conductive member 41 and the lower surface 42d of the large diameter portion 42fa may be substantially flush with each other.

[0034] From the second bottom surface 41R2 to the first bottom surface 41R1, the first recess 41R is recessed in a generally truncated cone shape. The second bottom surface 41R2 protrudes inward relative to the first bottom surface 41R1. Therefore, the side surface of the first recess 41R tapers so that the diameter gradually narrows from the first bottom surface 41R1 to the second bottom surface 41R2. In other words, the side surface of the first recess 41R tapers so that the diameter gradually increases from the second bottom surface 41R2 to the first bottom surface 41R1.

[0035] The second surface 41b is the surface opposite to the first surface 41a. In this embodiment, an annular rib 41ri is formed on the second surface 41b of the first conductive member 41. The rib 41ri can be formed continuously in an annular shape. An external conductive member 48 is welded to the second surface 41b via the rib 41ri. The external conductive member 48 preferably extends along the longitudinal direction of the sealing plate 24. The external conductive member 48 is preferably made of the same type of metal as the first conductive member 41 (in this embodiment, aluminum or an aluminum alloy).

[0036] As shown in FIG. 4, when the battery pack 200 is fabricated, a bus bar 90 is connected to the external conductive member 48, which is connected to the first conductive member 41. FIG. 5 is a schematic diagram of the external conductive member 48. FIG. 5 schematically illustrates the external conductive member 48 and the bus bar 90 as viewed from above. In FIG. 5, the second conductive member 42, which is hidden by the external conductive member 48, is indicated by a dashed line. As shown in FIG. 5, the bus bar 90 is connected to the external conductive member 48 at a bus bar weld 48a. The bus bar 90 and the external conductive member 48 can be welded by, for example, laser welding. Note that the external conductive member 48 does not necessarily have to be attached to the second surface 41b of the first conductive member 41. When the battery pack 200 (see FIG. 4) is fabricated, the bus bar 90 may be directly connected to the first conductive member 41 without the external conductive member 48.

[0037] <Second conductive member 42> As shown in FIG. 3, the second conductive member 42 is a member that extends from the inside to the outside of the case 20 through the terminal mounting hole 24h. The second conductive member 42 is made of a second metal different from the first metal. The second metal is, for example, a conductive metal such as copper, a copper alloy, nickel, stainless steel, iron, or an iron alloy. The second metal is preferably made of copper or a copper alloy. In this example, the second conductive member 42 is made of copper. The second conductive member 42 is preferably made of a metal that has a higher Vickers hardness (is harder) than the first conductive member 41. The second metal may be the same metal as the negative electrode current collecting member 14 or an alloy containing the same metal element as the first component. Part or all of the surface of the second conductive member 42 may be coated with another metal by Ni plating, tin plating, or the like.

[0038] The second conductive member 42 has a flange portion 42f and a shaft portion 42s (connection portion). The shaft portion 42s is connected to the negative current collecting member 14 and serves as the crimped portion 40c. The shaft portion 42s is provided on one surface (the lower surface 42d in this embodiment) of the flange portion 42f. The shaft portion 42s is inserted into the terminal mounting hole 24h of the case 20 (the sealing plate 24 in this embodiment) and the opening 14h of the negative current collecting member 14. A base portion 52 of a gasket 50 is disposed between the flange portion 42f and the sealing plate 24. A cylindrical portion 51 of the gasket 50 is disposed between the shaft portion 42s and the sealing plate 24. The diameter of the shaft portion 42s increases toward the tip. The increased diameter portion is connected to the negative current collecting member 14. The expanded diameter portion is also referred to as a crimped portion 40c, and is preferably inserted into the opening 14h of the negative current collector 14 and crimped to connect to the negative current collector 14. From the viewpoint of improving electrical conductivity, the crimped portion 40c and a part of the negative current collector 14 are preferably joined by laser welding or the like.

[0039] The flange portion 42f is a portion having a larger diameter than the shaft portion 42s in the planar directions (X direction and Y direction). In other words, the flange portion 42f is a portion at one end of the shaft portion 42s that has a larger diameter than the shaft portion 42s. The flange portion 42f is a portion that is disposed outside the case 20. The flange portion 42f is connected to the first conductive member 41.

[0040] The shape of the flange portion 42f is not particularly limited. The flange portion 42f may be, for example, substantially circular or substantially polygonal in plan view along the direction in which the shaft portion 42s extends (height direction). The flange portion 42f is preferably substantially circular in plan view. The substantially circular shape is not limited to a perfect circle, and includes shapes in which a notch is formed in part of the outer circumferential surface. It is preferable that at least a part of the outer circumferential edge of the flange portion 42f is circular. For example, it is preferable that the shape of the outer circumferential edge going around the entire circumference at the same height in the thickness direction of the flange portion 42f is circular.

[0041] Fig. 6 is a cross-sectional view of the negative electrode terminal 40. Fig. 6 shows a cross section near the interface between the first conductive member 41 and the second conductive member 42. Fig. 6 does not show the sealing plate 24, the gasket 50, the insulator 60, the negative electrode current collecting member 14, etc.

[0042] As shown in FIG. 6, the flange portion 42f has a large diameter portion 42fa and a small diameter portion 42fb. The large diameter portion 42fa has a larger diameter than the small diameter portion 42fb. The large diameter portion 42fa is a substantially disk-shaped portion having substantially the same diameter in the thickness direction (height direction). In other words, the outer periphery of the upper surface 42u of the large diameter portion 42fa is circular. A small diameter portion 42fb protruding upward is formed in the approximate center of the upper surface 42u of the large diameter portion 42fa. The small diameter portion 42fb is located farther from the shaft portion 42s than the large diameter portion 42fa. The large diameter portion 42fa and the small diameter portion 42fb are shaped to conform to the first recess 41R. The diameter of the small diameter portion 42fb increases toward the tip side (the side farther from the flange portion 42f). The diameter of the small diameter portion 42fb decreases from the tip to the base end. The diameter of the small diameter portion 42fb may be smaller than the diameter of the shaft portion 42s.

[0043] The negative electrode terminal 40 has a contact area C (contact portion where the first conductive member 41 and the second conductive member 42 come into contact) where the first conductive member 41 and the second conductive member 42 come into contact. In the contact area C, the first conductive member 41 and the flange portion 42f of the second conductive member 42 come into contact. A boundary C2 is formed on the outer surface of the negative electrode terminal 40 between the first conductive member 41 and the flange portion 42f of the second conductive member 42. The boundary C2 is the outermost peripheral portion of the contact area C and is formed linearly on the outer surface of the negative electrode terminal 40. The boundary C2 is continuous in the circumferential direction on the outer surface of the negative electrode terminal 40.

[0044] At least a portion of the flange portion 42f is disposed within the first recess 41R. A portion of the flange portion 42f of the second conductive member 42 contacts the first conductive member 41 in the first recess 41R. In the contact region C, the first conductive member 41 has a metal joint portion 45. The metal joint portion 45 is a joint portion where the first conductive member 41 and the flange portion 42f of the second conductive member 42 are joined by metal jointing. In this embodiment, the metal joint portion 45 is formed at the center of the upper surface of the flange portion 42f. This reduces the electrical resistance between the first conductive member 41 and the second conductive member 42, making it easier to ensure conductivity between the first conductive member 41 and the second conductive member 42. The metal joint portion 45 is preferably formed on the upper surface of the small diameter portion 42fb. The metal joint portion 45 is preferably formed radially inward of the fastening portion 43 of the flange portion 42f.

[0045] Here, metal bonding refers to joining multiple metal members together by metallurgical bonding, and does not include joining by mechanical fastening. Metal bonded portion 45 is preferably formed by ultrasonic bonding, diffusion bonding, laser welding, resistance welding, or the like. From the viewpoint of suppressing the formation of brittle intermetallic compounds at the bonding interface, metal bonded portion 45 is preferably an ultrasonic bonded portion formed by ultrasonic bonding. In this embodiment, metal bonded portion 45 is an ultrasonic bonded portion formed by ultrasonic bonding of first conductive member 41 and second conductive member 42.

[0046] In this embodiment, the metal joint 45 is formed on the upper surface 42u1 of the small diameter portion 42fb. From the viewpoint of suppressing corrosion due to an electrolyte, water, or the like, the metal joint 45 is preferably formed by metal-bonding the upper surface 42u1 of the small diameter portion 42fb of the flange portion 42f and the bottom surface of the recess of the first conductive member 41 (in this embodiment, the first bottom surface 41R1 of the first recess 41R). It is more preferable that the metal joint 45 be formed in a central portion of the upper surface of the flange portion 42f.

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

[0048] The fastening portion 43 is formed between the small diameter portion 42fb of the flange portion 42f and the first bottom surface 41R1 and the second bottom surface 41R2 of the first recess 41R. Here, the small diameter portion 42fb of the flange portion 42f is fitted into the side circumferential surface between the first bottom surface 41R1 and the second bottom surface 41R2 that protrudes inward within the first recess 41R of the first conductive member 41. In other words, the small diameter portion 42fb of the flange portion 42f is press-fitted into the first recess 41R of the first conductive member 41 and crimped to the side circumferential surface between the second bottom surface 41R2 and the first bottom surface 41R1. Note that, from the viewpoint of electrical conductivity between the members, it is preferable that no resin layer, insulating layer, or the like is provided between the first conductive member 41 and the second conductive member 42 in the fastening portion 43. Furthermore, since no resin layer, insulating layer, or the like is provided between the first conductive member 41 and the second conductive member 42 in the fastening portion 43, the fastening portion 43 can be joined more stably.

[0049] The form of the fastening portion 43 is not particularly limited as long as it is mechanically fastened by, for example, mechanical energy. The fastening portion 43 may be a portion fastened by, for example, press fitting, shrink fitting, caulking, riveting, folding, bolting, or the like.

[0050] The upper surface 42u of the large diameter portion 42fa contacts the first conductive member 41. In this embodiment, the upper surface 42u of the large diameter portion 42fa contacts the second bottom surface 41R2 of the first recess 41R of the first conductive member 41. This is not limited to the above embodiment, and the upper surface 42u of the large diameter portion 42fa may contact, for example, the first surface 41a of the first conductive member 41. The surface where the upper surface 42u of the large diameter portion 42fa contacts the first conductive member 41 can vary depending on the shapes of the first conductive member 41 and the second conductive member 42, etc.

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

[0052] The negative electrode terminal 40 is provided with a seal portion 44 .

[0053] <Seal part 44> The seal portion 44 is provided at an end C1 of the contact area C between the first conductive member 41 and the flange portion 42f of the second conductive member 42. The end C1 of the contact area C may include a boundary C2 of the contact area C. Here, the position of the end C1 of the contact area C is not particularly limited. The position of the end C1 of the contact area C may vary depending on the shapes of the first conductive member 41 and the second conductive member 42, etc. The end C1 of the contact area C may be located, for example, on a side surface or a bottom surface of the power storage device terminal (in this embodiment, the negative electrode terminal 40). In this embodiment, the end C1 of the contact area C is located on the bottom surface where the boundary C2 between the first surface 41a of the first conductive member 41 and the flange portion 42f of the second conductive member 42 is formed. In this embodiment, the lower surface of the negative electrode terminal 40 includes the first surface 41a of the first conductive member 41, the lower surface 42d of the flange portion 42f of the second conductive member 42, and a surface of the side circumferential surface of the flange portion 42f of the second conductive member 42 that protrudes slightly from the first surface 41a. The seal portion 44 seals the end C1 of the contact area C in the negative electrode terminal 40.

[0054] As described above, the seal portion 44 is provided at the end C1 of the contact area C between the first conductive member 41 and the flange portion 42f of the second conductive member 42. Providing the seal portion 44 at the end C1 makes it difficult for electrolyte and the like to penetrate into the contact area C. This makes it difficult for electrolyte and the like to penetrate into the fastening portion 43 where the outer peripheral side surface of the small diameter portion 42fb of the flange portion 42f is mechanically fastened to the inner surface of the first conductive member 41. This makes the fastening portion 43 less susceptible to corrosion, and the reliability of the fastening portion 43 is less likely to decrease.

[0055] Furthermore, even when a metal joint 45 is provided in which the first conductive member 41 and the flange portion 42f are joined on the gold side, the provision of the seal portion 44 makes it difficult for electrolyte or the like to penetrate into the metal joint 45. This makes the metal joint 45 less susceptible to corrosion, and the reliability of the metal joint 45 is less likely to decrease.

[0056] From the viewpoint of sealing performance of the contact region C, the seal portion 44 is preferably formed around the entire circumference of the end portion C1. However, the seal portion 44 does not necessarily have to be formed around the entire circumference of the end portion C1. The seal portion 44 is preferably formed over 50% or more of the circumferential length of the boundary C2, more preferably over 70%, and even more preferably over 90%. Note that when the seal portion 44 is not formed around the entire circumference of the end portion C1, the seal portion 44 may be provided continuously or intermittently along the circumferential direction of the end portion C1.

[0057] The configuration of the seal portion 44 is not particularly limited as long as it can seal the end C1 of the contact area C. The seal portion 44 may be a resin member 44a that covers the end C1 of the contact area C. The seal portion 44 may be a metal joint portion 44b (see FIG. 7) in which the first conductive member 41 and the flange portion 42f of the second conductive member 42 are metal-joined at the end C1 of the contact area C. The seal portion 44 may be a seal material 44c (see FIG. 8) that is sandwiched between the first conductive member 41 and the flange portion 42f of the second conductive member 42 at the end C1 of the contact area C. The resin member 44a, the metal joint portion 44b, and the seal material 44c that can be used as the seal portion 44 will be described below.

[0058] <Resin member 44a> As shown in FIG. 6 , the resin member 44a is provided as a seal portion 44 at an end C1 of the contact region C between the first conductive member 41 and the flange portion 42f of the second conductive member 42. In other words, the seal portion 44 is made of the resin member 44a. In this embodiment, the resin member 44a is provided so as to cover the boundary C2 between the first conductive member 41 and the flange portion 42f of the second conductive member 42. Here, the resin member 44a is formed at the end C1 in a state spanning the first surface 41a of the first conductive member 41 and the lower surface 42d of the flange portion 42f of the second conductive member 42. The resin member 44a can be provided along the end C1 (or the boundary C2) of the contact region C after the first conductive member 41 and the second conductive member 42 are fastened together to form the fastening portion 43. This improves the positional accuracy of the end C1 and the resin member 44a, thereby improving the sealing performance of the end C1.

[0059] The method for providing the resin member 44a on the end C1 is not particularly limited. The resin member 44a may be provided on the end C1 by, for example, applying a resin material, welding a film-like resin (sealant film), insert molding, or the like. Note that, in order to improve the bonding between the resin member 44a and the portion where the resin member 44a is formed, the portion may be subjected to a treatment such as surface roughening. Note that the type of the resin member 44a provided on the end C1 is not particularly limited. For example, synthetic resin materials such as polyolefin resin and fluorinated resin can be used as the resin member 44a. Examples of polyolefin resins that can be used include polypropylene (PP) and polyethylene (PE). Examples of fluorinated resins that can be used include perfluoroalkoxyalkane and polytetrafluoroethylene (PTFE).

[0060] As described above, the resin member 44a is attached to the end C1 of the contact region C of the negative electrode terminal 40. The resin member 44a is a separate member from the insulating member (in this embodiment, the gasket 50) that is disposed between the sealing plate 24 of the case 20 and the negative electrode terminal 40 in the energy storage device 100. Note that a recess for accommodating the resin member 44a may be provided in a portion of the base 52 of the gasket 50 that is disposed between the sealing plate 24 and the negative electrode terminal 40, corresponding to the resin member 44a. The dimensions of the recess may be determined according to the dimensions of the resin member 44a. This reduces interference between the resin member 44a and the gasket 50, thereby maintaining the quality of the resin member 44a.

[0061] <Metal joint 44b> FIG. 7 is a cross-sectional view of a negative electrode terminal 40A according to another embodiment. As shown in FIG. 7, a metal joint 44b is provided as a seal portion 44 at an end C1 of a contact region C between the first conductive member 41 and the flange portion 42f of the second conductive member 42. The metal joint 44b is a portion where the first conductive member 41 and the second conductive member 42 are metal-joined at the end C1 of the contact region C. Here, the metal joint 44b is formed to include a boundary C2 at the outermost periphery of the contact region C. In this embodiment, the metal joint 44b is a portion where an inner peripheral side surface 41R4 of the first recess 41R of the first conductive member 41 is metal-joined to an outer peripheral side surface 42fa1 of the flange portion 42f of the second conductive member 42. The metal joint 44b is preferably formed at a position away from the metal joint 45.

[0062] Because the end C1 of the contact region C is a metal joint 44b, the first conductive member 41 and the second conductive member 42 are directly joined at the end C1. At the end C1 of the contact region C, a surface bond can be formed from the outermost periphery (boundary C2) of the contact region C to the region along the contact region C. This makes it difficult for gaps to form between the first conductive member 41 and the flange portion 42f of the second conductive member 42, and thus makes it difficult for electrolytes and the like to penetrate into the fastening portion 43. This makes the fastening portion 43 less susceptible to corrosion, which tends to improve the reliability of the fastening portion 43. Furthermore, the electrical resistance between the first conductive member 41 and the second conductive member 42 is also low at the metal joint 44b. This makes it easier to ensure conductivity between the first conductive member 41 and the second conductive member 42.

[0063] The metal joint 44b is not particularly limited as long as the end C1 of the contact region C is metallurgically joined. In the metal joint 44b, metals are joined by fusion welding, solid-state welding, diffusion bonding, or the like. The metal joint 44b is preferably formed by, for example, laser welding, friction stir welding, brazing, soldering, or the like. Note that the metal joint 44b does not include a joint between the first conductive member 41 and the flange portion 42f of the second conductive member 42 that is joined only by mechanical fastening (for example, pressure welding, etc.).

[0064] <Sealing material 44c> FIG. 8 is a cross-sectional view of a negative electrode terminal 40B according to another embodiment. As shown in FIG. 8, a seal material 44c is provided as a seal portion 44 at an end C1 of a contact region C between the first conductive member 41 and the flange portion 42f of the second conductive member 42. In this embodiment, the outer peripheral side surface 42fa1 of the flange portion 42f of the second conductive member 42 tapers so that its diameter decreases toward the upper surface 42u. The inner peripheral side surface 41R4 of the first recess 41R of the first conductive member 41 tapers so that its diameter decreases in the direction in which the first recess 41R deepens. In this embodiment, the seal material 44c is interposed between the outer peripheral side surface 42fa1 of the flange portion 42f and the inner peripheral side surface 41R4 of the first recess 41R.

[0065] The sealing material 44c can be formed on at least one of the inner peripheral side surface 41R4 of the first recess 41R of the first conductive member 41 or the outer peripheral side surface 42fa1 of the flange portion 42f of the second conductive member 42. Then, the flange portion 42f of the second conductive member 42 is inserted into the first recess 41R of the first conductive member 41. In this way, the sealing material 44c can be provided at the end C1.

[0066] The inner diameter of the inner peripheral side surface 41R4 of the first recess 41R is slightly larger than the outer diameter of the outer peripheral side surface 42fa1 of the flange portion 42f. The thickness of the sealing material 44c may be larger than the difference between the inner diameter of the inner peripheral side surface 41R4 of the first recess 41R and the outer diameter of the outer peripheral side surface 42fa1 of the flange portion 42f. This makes it easier to fill gaps at the boundary surfaces between the first conductive member 41 and the second conductive member 42.

[0067] The type of the seal portion 44 and the shapes of the first conductive member 41 and the second conductive member 42 that constitute the negative electrode terminal are not limited to those of the above-described embodiment. Fig. 9 is a cross-sectional view of a negative electrode terminal 40C according to another embodiment.

[0068] 9, the shapes of the first conductive member 41 and the second conductive member 42 are similar to those of the negative electrode terminal 40B shown in FIG. 8, except that the sealant 44c is not provided. The outer peripheral side surface 42fa1 of the flange portion 42f of the second conductive member 42 and the inner peripheral side surface 41R4 of the first recess 41R of the first conductive member 41 are tapered so that their diameters decrease upward. Here, a resin member 44a serving as a sealant 44 is provided at an end C1 of the contact region C between the first conductive member 41 and the flange portion 42f of the second conductive member 42.

[0069] The shapes and dimensions of the first conductive member 41 and the second conductive member 42 that constitute the negative electrode terminal may be set as appropriate.

[0070] In the negative electrode terminal 40, the outer diameter of the small diameter portion 42fb is set to be smaller than the outer diameter of the large diameter portion 42fa. By making the outer diameter of the small diameter portion 42fb smaller than the outer diameter of the large diameter portion 42fa, a sufficient distance is ensured between the fastening portion 43 formed on the outer peripheral side surface of the small diameter portion 42fb and the boundary between the first conductive member 41 and the second conductive member 42. The length of contact between the upper surface 42u of the large diameter portion 42fa and the first conductive member 41 along the radial direction of the flange portion 42f is increased. This configuration makes it difficult for the electrolyte or water to reach the small diameter portion 42fb, even if, for example, the electrolyte comes into contact with the exposed portion of the boundary between the first conductive member 41 and the second conductive member 42 due to vibration during use of the energy storage device 100. As a result, deterioration in the reliability of the fastening portion 43 due to corrosion at the interface between the first conductive member 41 and the second conductive member 42 is suppressed. According to the findings of the present inventors, when the outer diameter of the small diameter portion 42fb is 9 / 10 or less of the outer diameter of the large diameter portion 42fa, the deterioration of the reliability of the fastening portion 43 is effectively suppressed.

[0071] The outer diameters of the large diameter portion 42fa and the small diameter portion 42fb refer to the outer shapes of the portions of each portion that have the largest diameter from the central axis CL. In this embodiment, the outer diameter of the small diameter portion 42fb refers to the outer diameter of the upper surface 42u1 on the tip side of the small diameter portion 42fb. In this embodiment, the outer diameter of the large diameter portion 42fa is approximately constant in the axial direction, and therefore refers to the outer diameter at any position in the axial direction.

[0072] For example, the outer diameter of the small diameter portion 42fb is preferably 4 / 5 or less, and even more preferably 2 / 3 or less, of the outer diameter of the large diameter portion 42fa. This further improves the reliability of the fastening portion 43. Also, for example, the difference between the outer diameter of the large diameter portion 42fa and the outer diameter of the small diameter portion 42fb is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. Note that the outer diameter of the small diameter portion 42fb is preferably 1 / 5 or more of the outer diameter of the large diameter portion 42fa. This further improves the reliability of the fastening portion 43.

[0073] The fastening portion 43 is disposed at a position away from the end C1 of the contact region C. In this embodiment, the end C1 of the contact region C is the position where the opening 41R3 of the first recess 41R of the first conductive member 41 is formed. The end C1 is a portion exposed from the contact surface between the first conductive member 41 and the second conductive member 42. From the viewpoint of suppressing corrosion due to the electrolyte, water, or the like, the fastening portion 43 is preferably disposed at a position away from the end C1 of the contact region C. The shortest creepage distance between the fastening portion 43 and the end C1 of the contact region C is, for example, preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. Here, the creepage distance is the distance along the contact region C. In this embodiment, it is the distance from the opening 41R3 of the first recess 41R of the first conductive member 41 to the base end of the small diameter portion 42fb of the second conductive member 42, and is the distance along the inner circumferential side surface of the first conductive member 41 or the outer circumferential side surface of the second conductive member 42.

[0074] In the above-described embodiment, the contact area C is also formed on the outer peripheral side surface of the large diameter portion 42fa of the flange portion 42f. As a result, the shortest creepage distance between the fastening portion 43 and the end C1 of the contact area C is longer by the length of the contact area C on the outer peripheral side surface of the large diameter portion 42fa. This makes the fastening portion 43 less susceptible to corrosion by the electrolyte, water, or the like.

[0075] In a configuration in which the inner peripheral side surface of the first recess 41R is disposed radially outward of the outer peripheral side surface of the large diameter portion 42fa, a gap may be provided between the outer peripheral side surface of the large diameter portion 42fa and the inner peripheral side surface of the first recess 41R. This configuration can form a more stable fastening portion 43. Although not particularly limited, the gap between the outer peripheral side surface of the large diameter portion 42fa and the inner peripheral side surface of the first recess 41R may be, for example, 1 mm or less, or 0.5 mm or less. A sealant 44c can be accommodated in this gap.

[0076] Furthermore, the first conductive member 41 and the second conductive member 42 may be provided with various connection structures other than the fastening portion 43 and the metal joint portion 45 described above.

[0077] In this embodiment, a groove 42fc is provided on the outer peripheral side surface of the flange portion 42f (in this embodiment, the small diameter portion 42fb). The groove 42fc is a portion where a part of the flange portion 42f is narrowed, and is also referred to as a narrowed portion. A part of the first conductive member 41 is disposed in the groove 42fc. With this configuration, the first conductive member 41 and the second conductive member 42 are more firmly fastened together, which may improve the reliability of the negative electrode terminal 40. The groove 42fc is formed at the boundary between the large diameter portion 42fa and the small diameter portion 42fb. The groove 42fc may be formed continuously, intermittently, or partially along the circumferential direction of the flange portion 42f. The groove 42fc is preferably formed continuously in an annular shape along the circumferential direction of the flange portion 42f. In this embodiment, the groove 42fc is continuous in the circumferential direction, and the outer peripheral edge of the narrowest portion (narrowed portion) of the groove 42fc is circular. The ratio of the length of the groove 42fc to the circumferential length is preferably 0.5 or more, more preferably 0.7 or more, and even more preferably 0.9 or more. Here, the circumferential length refers to the circumferential length of the portion of the side circumferential surface of the flange portion 42f where the groove 42fc is formed.

[0078] In this embodiment, the second conductive member 42 is provided with a protrusion 42p. The protrusion 42p is provided on the outer periphery of the metal joint 45. The protrusion 42p is provided in the contact region C between the first conductive member 41 and the second conductive member 42. The protrusion 42p is formed on the upper surface 42u of the large diameter portion 42fa of the upper surface of the flange portion 42f. The protrusion 42p is provided in a position on the second conductive member 42 away from the end C1 of the contact region C. The shortest creeping distance between the protrusion 42p and the end C1 of the contact region C is preferably 1 mm or more, more preferably 2 mm or more, and even more preferably 3 mm or more. The protrusion 42p is preferably provided radially inward of a position 0.9 times the diameter of the flange portion 42f from the center axis CL, more preferably 0.8 times the diameter, and even more preferably 0.6 times the diameter.

[0079] FIG. 10 is a perspective view of the second conductive member 42. FIG. 11 is a schematic diagram of a protrusion 42p. FIG. 12 is a schematic diagram of a protrusion 42p according to another embodiment. As shown in FIG. 10, the protrusion 42p is provided on the upper surface 42u of the large diameter portion 42fa in the vicinity of the small diameter portion 42fb. The protrusion 42p may be connected to the small diameter portion 42fb or may be separated from the small diameter portion 42fb. In this embodiment, the protrusion 42p is connected to the small diameter portion 42fb and is provided along the radial direction from the base end of the small diameter portion 42fb.

[0080] The protrusion 42p is preferably provided on the upper surface 42u of the large diameter portion 42fa near the base of the small diameter portion 42fb. This can reduce the risk of corrosion at the interface between the protrusion 42p and the second recess 41r due to the electrolyte, water, or the like. For example, the protrusion 42p is preferably provided on the upper surface 42u of the large diameter portion 42fa at a position within 5 mm of the base of the small diameter portion 42fb, more preferably within 3 mm, and even more preferably within 1 mm.

[0081] As shown in FIG. 11, the protrusion 42p has a flat tip. The cross section of the protrusion 42p along the length direction (radial direction of the flange portion 42f) is generally trapezoidal. The shape of the protrusion 42p is not limited to this, and as shown in FIG. 12, the protrusion 42p may have a pointed tip. The cross section of the protrusion 42p along the length direction may be generally triangular. The dimensions and shape of the protrusion 42p are not particularly limited. From the viewpoint of durability of the protrusion 42p, it is preferable that the aspect ratio A / B, which is expressed as the width A of the base end of the protrusion 42p to the height B of the protrusion 42p, be 1 or greater.

[0082] As shown in Figures 10 and 11, the protrusions 42p are formed along the radial direction. The length of the protrusions 42p in the radial direction is not particularly limited. For example, the length of the protrusions 42p in the radial direction is preferably 0.25 mm or more, and more preferably 0.5 mm or more. Furthermore, the length of the protrusions 42p in the radial direction is preferably 5 mm or less, and more preferably 3 mm or less.

[0083] As shown in FIG. 5, six protrusions 42p are provided on the upper surface 42u of the large diameter portion 42fa of the flange portion 42f. The six protrusions 42p are provided at approximately the same distance from the center in the radial direction. The protrusions 42p may be provided, for example, at approximately equal intervals in the circumferential direction. The number, arrangement, intervals, etc. of the protrusions 42p are not particularly limited. The number of protrusions 42p may be one. From the viewpoint of improving the conductivity between the first conductive member 41 and the second conductive member 42, the number of protrusions 42p is preferably more than one, and more preferably four or more. From the viewpoint of productivity, the number of protrusions 42p may be, for example, 20 or less, 12 or less, or 8 or less.

[0084] As shown in FIG. 6 , the protrusions 42p of the second conductive member 42 bite into the first conductive member 41. In other words, the first conductive member 41 has second recesses 41r that fit with the protrusions 42p of the second conductive member 42. The first conductive member 41 has the same number of second recesses 41r as the protrusions 42p of the second conductive member 42. The second recesses 41r are formed in the same positions as the protrusions 42p and in shapes corresponding to the protrusions 42p. In this way, the protrusions 42p of the second conductive member 42 and the second recesses 41r of the first conductive member 41 fit into the interface between the first conductive member 41 and the second conductive member 42. With this configuration, the first conductive member 41 and the second conductive member 42 can be more firmly fastened together. Furthermore, even when an external connecting member such as the bus bar 90 applies a force in the circumferential direction about the central axis CL of the negative electrode terminal 40 (see FIG. 4), a load is unlikely to be applied in a direction that rotates the first conductive member 41 relative to the second conductive member 42. This makes it easier to maintain the metal joint 45 in the negative electrode terminal 40, and can improve the reliability of conduction between the first conductive member 41 and the second conductive member 42. From this perspective, it is preferable to provide a plurality of second recesses 41r and protrusions 42p.

[0085] A metal bond may be formed at the interface between the second recess 41r of the first conductive member 41 and the protrusion 42p of the second conductive member 42. This can improve the conductivity between the first conductive member 41 and the second conductive member 42.

[0086] In the above-described embodiment, the second conductive member 42 has a protrusion 42p. The first conductive member 41 has a second recess 41r into which the protrusion 42p fits. However, this is not limited to such an embodiment. At least one of the first conductive member and the second conductive member may have a protrusion, and the other may have a second recess. For example, the first conductive member may have a protrusion, and the second conductive member may have a second recess into which the protrusion fits. Alternatively, both the first conductive member and the second conductive member may have a protrusion. In this case, the first conductive member and the second conductive member may each have a second recess into which the protrusion of the other fits.

[0087] However, from the viewpoint of fitting a protrusion provided on one conductive member into the other conductive member, it is preferable to provide the protrusion on the conductive member made of a metal with a higher Vickers hardness, between first conductive member 41 and second conductive member 42. From this viewpoint, it is preferable that second conductive member 42 has at least protrusion 42p.

[0088] The form of the fastening portion 43 is not particularly limited as long as it is mechanically fastened by, for example, mechanical energy. The fastening portion 43 may be a portion fastened by, for example, press fitting, shrink fitting, caulking, riveting, folding, bolting, or the like.

[0089] <Method of manufacturing the negative electrode terminal 40> The negative electrode terminal 40 described above can be manufactured, for example, by the manufacturing method for a terminal for an electric storage device (in this embodiment, the negative electrode terminal 40) described below. The manufacturing method for a terminal for an electric storage device includes a preparation step of preparing a first conductive member 41 and a second conductive member 42, a fastening step of fastening the first conductive member 41 and the second conductive member 42 together, a metal joining step of metal-joining the first conductive member 41 and the second conductive member 42 together, and a sealant forming step of providing a seal portion 44. The manufacturing method for a terminal for an electric storage device may include other steps.

[0090] In the preparation step, a first conductive member 41 and a second conductive member 42 are prepared. A second metal having the shape described above is prepared as the second conductive member 42. In this embodiment, a metal having lower rigidity than the second conductive member 42 is used as the first conductive member 41. The first conductive member 41 is prepared in a shape that deforms along the large diameter portion 42fa, the small diameter portion 42fb, and the groove 42fc of the second conductive member 42 when it is crimped in the fastening step.

[0091] In the fastening step, the first conductive member 41 and the second conductive member 42 are mechanically fastened together. In this embodiment, the first conductive member 41 and the second conductive member 42 are mechanically fastened together by crimping the first conductive member 41 to the second conductive member 42.

[0092] In the fastening process, first, the first conductive member 41 is placed in a mold (not shown). In this embodiment, the second conductive member 42 is pressed against the first conductive member 41 so that the flange portion 42f of the second conductive member 42 is inserted into the first recess 41R of the first conductive member 41. At this time, a known pressing device (not shown) or the like may be used. The first conductive member 41 is crushed because it has lower rigidity than the second conductive member 42, and is plastically deformed along the second conductive member 42. The edge of the first recess 41R of the first conductive member 41 is press-fitted into the groove 42fc of the second conductive member 42, and the first conductive member 41 and the second conductive member 42 are fastened together. In the fastening process, as described above, various fastening methods for mechanically fastening the first conductive member 41 and the second conductive member 42 can be employed.

[0093] A gap may be provided between the outer peripheral side surface of the large diameter portion 42fa and the inner peripheral side surface of the first recess 41R. This configuration makes it easier for the large diameter portion 42fa to be inserted into the first recess 41R, and makes it easier to form a stable fastening portion 43.

[0094] A protrusion 42p is provided on the second conductive member 42. When the second conductive member 42 is pressed against the first conductive member 41 in the fastening step, the protrusion 42p may sink into the first conductive member 41, and a second recess 41r may be formed in the first conductive member 41.

[0095] After the first conductive member 41 and the second conductive member 42 are fastened together to form the fastening portion 43, the first conductive member 41 and the second conductive member 42 are then metal-joined.

[0096] In the metal joining process, a metal joint 45 is formed at the interface between the first conductive member 41 and the second conductive member 42. In this embodiment, the first conductive member 41 and the second conductive member 42 are metal-joined using an ultrasonic welding device. Although detailed illustration is omitted, in the metal joining process, the fastened first conductive member 41 and second conductive member 42 are sandwiched between a horn and anvil, and ultrasonic vibration is applied to the joining interface via the horn. For example, an anvil may be inserted into the cylindrical portion of the shaft portion 42s of the second conductive member 42, and ultrasonic vibration may be applied to the first conductive member 41 while pressing the horn against approximately the center of the second surface 41b of the first conductive member 41. As a result, a metal joint 45 is formed at approximately the center of the interface between the first bottom surface 41R1 of the first recess 41R of the first conductive member 41 and the upper surface 42u1 of the small diameter portion 42fb of the second conductive member 42. When the horn is pressed against the first conductive member 41, the first conductive member 41 is pressed against the second conductive member 42. As a result, the protrusion 42p may sink into the first conductive member 41, and a second recess 41r may be formed in the first conductive member 41.

[0097] In the metal bonding process, ultrasonic vibrations are applied to the first conductive member 41, which can cause the first conductive member 41 to vibrate at the contact interface between the second recess 41r of the first conductive member 41 and the protrusion 42p of the second conductive member 42. This can also form a metal bond at the contact interface between the second recess 41r and the protrusion 42p. From the viewpoint of facilitating the formation of a metal bond, it is preferable that the protrusion have a tapered shape (a shape with a small area at the tip) toward the tip.

[0098] The closer the position of the horn to the contact position, the easier it is for the ultrasonic vibrations applied by the horn to be transmitted. Therefore, the closer the positions of the protrusion 42p and the second recess 41r are to the position of the horn contact position (in this embodiment, approximately the center of the second surface 41b of the first conductive member 41), the easier it is for a good metal bond to be formed at the interface between the protrusion 42p and the second recess 41r.

[0099] In the above-described embodiment, the second conductive member 42 prepared in the preparation step is provided with a protrusion 42p in advance. However, this is not limited to this embodiment, and the first conductive member prepared in the preparation step may be provided with a protrusion in advance. Furthermore, in the preparation step, a first recess may be provided in advance in at least one of the first conductive member and the second conductive member. In the fastening step, a protrusion that matches the first recess of one of the first conductive member and the second conductive member may be formed in the other of the first conductive member and the second conductive member. However, from the perspective of firmly fastening the protrusion 42p and the second recess 41r, it is preferable that a protrusion be provided in advance at the position where the second metal joint is to be formed.

[0100] In the seal portion forming process, a seal portion 44 is formed at the end C1 of the contact area C between the first conductive member 41 and the flange portion 42f of the second conductive member 42. If the seal portion 44 is the resin member 44a or the metal joint portion 44b described above, the seal portion forming process can be performed after the fastening process and the metal joint process. If the seal portion 44 is the sealing material 44c described above, the seal portion forming process can be performed before the fastening process and the metal joint process. The method for forming the seal portion 44 at the end C1 has been described above, so a detailed description thereof will be omitted.

[0101] The configuration of the negative electrode terminal 40 is not limited to the above-described embodiment. FIG. 13 is a cross-sectional view of a negative electrode terminal 40D according to another embodiment. FIG. 14 is a cross-sectional view of a negative electrode terminal 40E according to another embodiment. FIG. 15 is a cross-sectional view of a negative electrode terminal 40F according to another embodiment. FIG. 16 is a cross-sectional view of a negative electrode terminal 40G according to another embodiment. FIG. 17 is a cross-sectional view of a negative electrode terminal 40H according to another embodiment. In FIGS. 13 to 17, components common to the above-described negative electrode terminal 40 are denoted by the same reference numerals, and detailed description thereof will be omitted. Note that in the embodiment shown in FIGS. 14 to 17, the seal portion 44 covers the end C1 of the contact region C so as to overlap the first surface 41a of the first conductive member 41 and the lower surface 41u of the large diameter portion 42fa of the second conductive member 42.

[0102] In the negative electrode terminal 40D shown in FIG. 13, the first recess 41R of the first conductive member 41 is shaped and sized so that only the small diameter portion 42fb of the flange portion 42f of the second conductive member 42 is disposed therein. The first recess 41R does not have a second bottom surface 41R2 (see FIG. 6). The shape of the first recess 41R follows the shape of the small diameter portion 42fb. In this embodiment, the upper surface of the large diameter portion 42fa of the flange portion 42f is in contact with the first surface 41a of the first conductive member 41. The dimensional relationship between the large diameter portion 42fa of the second conductive member 42 and the first conductive member 41 in the radial direction of the flange portion 42f is not particularly limited. In this embodiment, the dimensions of the large diameter portion 42fa of the second conductive member 42 and the first conductive member 41 are set to be approximately the same. This allows the size of the small diameter portion 42fb to be increased and the depth of the first recess 41R to be deepened while maintaining the outer diameter of the negative electrode terminal 40D. This can increase the bonding strength at the fastening portion 43. Furthermore, by increasing the proportion of the second conductive member 42 in the negative electrode terminal 40D, the conductivity between the first conductive member 41 and the second conductive member 42 can be improved. As a result, heat generation during current flow is suppressed, and the durability of the energy storage device 100 can be improved. In this embodiment, the seal portion 44 covers the end C1 of the contact region C so as to overlap the side circumferential surface 41c of the first conductive member 41 and the outer circumferential side surface 42fa1 of the large diameter portion 42fa of the second conductive member 42. Since the dimensions of the large diameter portion 42fa of the second conductive member 42 and the first conductive member 41 are approximately the same, a step is less likely to be formed at the end C1, and the sealing performance of the seal portion 44 can be improved.

[0103] In the negative electrode terminal 40E shown in FIG. 14, the protrusion 42p is provided on the upper surface 42u of the large diameter portion 42fa of the flange portion 42f. The protrusion 42p is provided in the approximate center between the peripheral edge of the large diameter portion 42fa and the base end of the small diameter portion 42fb. In this manner, the protrusion 42p does not necessarily have to be provided near the base of the small diameter portion 42fb. By providing the protrusion 42p at a position away from the base of the small diameter portion 42fb, durability against a load applied in a direction that rotates the first conductive member 41 relative to the second conductive member 42 can be improved.

[0104] 15, the protrusion 42p is provided on the upper surface 42u1 of the small diameter portion 42fb of the flange portion 42f. With this configuration, the interface between the protrusion 42p and the second recess 41r is farther from the end C1 of the contact region C. As a result, corrosion of the interface between the protrusion 42p and the second recess 41r due to the electrolyte, water, or the like can be reduced.

[0105] In the negative electrode terminal 40G shown in Fig. 16 and the negative electrode terminal 40H shown in Fig. 17, the cross section of the protrusion 42p is substantially triangular in the circumferential direction of the flange portion 42f. Because the tip of the protrusion 42p has a pointed shape in the cross section along the circumferential direction of the flange portion 42f, ultrasonic vibrations are easily applied to the interface between the first conductive member 41 and the second conductive member 42 while they are in contact with each other. As a result, a metal bond is easily formed at the interface between the protrusion 42p and the second recess 41r.

[0106] The technology disclosed herein has been described in various ways. Unless otherwise specified, the embodiments and the like described herein do not limit the present invention. Furthermore, the technology disclosed herein can be modified in various ways, and as long as no particular problems arise, each component and each process described herein can be omitted or combined as appropriate. Furthermore, this specification includes the disclosures described in the following sections.

[0107] Section 1: a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal for a power storage device, comprising: the first conductive member has a first recess on a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, The flange portion has a large diameter portion and a small diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer peripheral side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, a seal portion is provided at an end of a contact area between the first conductive member and the flange portion of the second conductive member; Terminal for power storage device.

[0108] Section 2: Item 2. The terminal for a power storage device according to item 1, wherein the first conductive member has a metal joint portion that is metal-jointed to the flange portion.

[0109] Section 3: 3. The terminal for a power storage device according to item 1 or 2, wherein the small diameter portion has an outer diameter that is 9 / 10 or less of the outer diameter of the large diameter portion.

[0110] Section 4: 4. The terminal for a power storage device according to any one of items 1 to 3, wherein a groove is provided on an outer circumferential side surface of the small diameter portion, and a part of the first conductive member is disposed in the groove.

[0111] Section 5: 5. The terminal for a power storage device according to any one of items 1 to 4, wherein the sealing portion is made of a resin member.

[0112] Item 6: 3. The terminal for a power storage device according to item 1 or 2, wherein the sealing portion is a metal joint portion between the first conductive member and the second conductive member.

[0113] Section 7: an electrode assembly including a positive electrode and a negative electrode; a case for accommodating the electrode assembly; a terminal electrically connected to the positive electrode or the negative electrode and attached to the case; Equipped with The terminal is a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal for a power storage device, comprising: the first conductive member has a first recess on a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, The flange portion has a large diameter portion and a small diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer peripheral side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, a seal portion is provided at an end of a contact area between the first conductive member and the flange portion of the second conductive member; Energy storage device. [Explanation of symbols]

[0114] 10 Electrode body 11 Positive electrode current collector 12 Negative electrode current collector 13 Positive electrode current collecting member 14 Negative electrode current collecting member 20 cases 22 Exterior body 22d bottom 22h opening 24 Sealing plate 24h terminal mounting hole 30 Positive terminal 40,40A~40E Negative terminal 40c Crimped part 41 First conductive member 41a 1st page 41b 2nd side 41c Side surface 41R 1st recess 41R1 1st bottom 41R2 2nd bottom 41R3 opening 41R4 Inner circumference side 41r 2nd recess 41ri rib 42 second conductive member 42d Bottom surface 42f flange 42fa large diameter section 42fa1 Outer periphery side 42fb Small diameter section 42fc groove 42p protrusion 42s shaft part 42u top 42u1 top surface 43 Fastening part 44 Seal part 44 44a Resin material 44b Metal joint 44b 44c sealing material 45 Metal joints 48 External conductive members 48a Busbar weld 50 gaskets 60 insulator 90 Busbar 100 Electricity storage device 200 battery packs C Contact area C1 end C2 boundary CL center axis

Claims

1. a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal for a power storage device, comprising: the first conductive member has a first recess in a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, The flange portion has a large diameter portion and a small diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer peripheral side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, a seal portion is provided at an end of a contact area between the first conductive member and the flange portion of the second conductive member; Terminal for power storage device.

2. The terminal for a power storage device according to claim 1 , wherein the first conductive member has a metal joint portion that is metal-jointed to the flange portion.

3. 3. The terminal for use with an electric storage device according to claim 1, wherein an outer diameter of the small diameter portion is 9 / 10 or less of an outer diameter of the large diameter portion.

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

5. The terminal for use in an electric storage device according to claim 1 or 2, wherein the sealing portion is made of a resin material.

6. The terminal for a power storage device according to claim 1 , wherein the sealing portion is a metal joint portion between the first conductive member and the second conductive member.

7. an electrode assembly including a positive electrode and a negative electrode; a case for accommodating the electrode assembly; a terminal electrically connected to the positive electrode or the negative electrode and attached to the case; Equipped with The terminal is a first conductive member made of a first metal; a second conductive member made of a second metal different from the first metal; A terminal for a power storage device, comprising: the first conductive member has a first recess in a first surface; the second conductive member has a flange portion and a shaft portion provided on one surface of the flange portion, At least a portion of the flange portion is disposed within the first recess, The flange portion has a large diameter portion and a small diameter portion, the small diameter portion is located farther from the shaft portion than the large diameter portion, an outer peripheral side surface of the small diameter portion has a fastening portion that is mechanically fastened to an inner surface of the first recess, a seal portion is provided at an end of a contact area between the first conductive member and the flange portion of the second conductive member; Energy storage device.

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