Secondary battery and method for manufacturing secondary battery

Abstract

The invention provides a secondary battery with improved conduction reliability and a method for manufacturing the secondary battery. A terminal for a secondary battery disclosed herein is provided with: a plate-shaped first conductive member (41); a second conductive member (42) electrically connected to the first conductive member (41); a fastening part (43) that mechanically fixes the first conductive member (41) and the flange part (42f) of the second conductive member (42); and a metal joining section (45) that metal-joins the first conductive member (41) and the flange section (42f) of the second conductive member (42) at a position separated from the fastening section (43).

Description

[0001] This invention application is a divisional application of an invention patent application with an application date of September 15, 2021, an application number of 202111077947.9, and an invention name of “Terminal, secondary battery having the terminal, and their manufacturing method”. Technical Field

[0002] The present invention relates to a secondary battery and a method for manufacturing the secondary battery. Background Art

[0003] Typically, batteries such as lithium-ion secondary batteries include an electrode body having an electrode and a battery case that accommodates the electrode body. In such batteries, it is known that there is a terminal that leads the terminal electrically connected to the electrode inside the battery case to the outside of the battery case. As a prior art related to the terminal, for example, Patent Document 1 discloses a terminal structure, which includes: a rivet member that is electrically connected to the electrode inside the battery case and is inserted through a through hole of the battery case to protrude to the outside; and a pulling member that has a first through hole for the rivet member to be inserted through and electrically connects the rivet member to a terminal bolt for external connection. Patent Document 1 states the following: By inserting the rivet member through the first through hole of the pulling member and riveting the end portion in the up and down direction, the rivet member is riveted and fixed to the peripheral portion of the pulling member surrounding the first through hole, and the rivet member is electrically connected to the pulling member.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 6216368

[0007] However, according to the research of the inventors, it has been confirmed that there is room for improvement in the above technology. That is, when the battery is in use, external forces such as vibration and impact may be applied to the battery from the outside. As a result, the riveted part will shake and deform, which may cause a gap between the rivet member and the pulling member. As a result, the conductive connection of the terminal may become unstable or poorly connected. Therefore, it is required to improve the conductive reliability of the terminal. Summary of the invention

[0008] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a terminal having improved conduction reliability, a secondary battery including the terminal, and methods for manufacturing the same.

[0009] According to the present invention, there is provided a terminal comprising: a first plate-shaped conductive member; a second conductive member having a flange portion electrically connected to the first conductive member; a fastening portion mechanically fixing the first conductive member and the flange portion of the second conductive member; and a metal joining portion metal-joining the first conductive member and the flange portion of the second conductive member at a position separated from the fastening portion.

[0010] The terminal has two connection parts with different connection methods, namely, a fastening part and a metal joint part. Therefore, even if vibration, impact, etc. are applied from the outside, it is difficult to cause deformation, and it is easy to maintain the state of close contact between the first conductive member and the second conductive member. Therefore, the conductive connection between the first conductive member and the second conductive member can be stably maintained, and the conductive reliability can be improved.

[0011] In a preferred embodiment of the terminal disclosed herein, the first conductive member has a recessed portion for receiving at least a portion of the flange portion of the second conductive member, and the fastening portion is formed by fixing the inner wall of the recessed portion of the first conductive member to the portion of the second conductive member received in the recessed portion. Thus, the strength of the fastening portion can be improved.

[0012] In a preferred embodiment of the terminal disclosed herein, the flange portion of the second conductive member has a constricted portion that fits with the first conductive member, and the fastening portion is a fitting portion formed by the constricted portion of the second conductive member and the first conductive member. Since the second conductive member has a constricted portion, even if the two conductive members are made of dissimilar metals, they can be properly fixed. In addition, the workability when forming the fastening portion can be improved.

[0013] In a preferred embodiment of the terminal disclosed herein, the flange portion of the second conductive member has a through hole, the first conductive member has a leg portion inserted into the through hole, and the fastening portion is configured to insert the leg portion of the first conductive member into the through hole of the second conductive member. Thus, the strength of the fastening portion can be improved. In addition, the workability when forming the fastening portion can be improved.

[0014] In a preferred embodiment of the terminal disclosed herein, the fastening portion is a caulking portion formed by caulking the distal end of the leg portion at the peripheral edge of the through hole. This can improve workability when forming the fastening portion.

[0015] In a preferred embodiment of the terminal disclosed herein, the metal joint is a welded joint. By welding, a high-strength metal joint can be stably formed.

[0016] In a preferred embodiment of the terminal disclosed herein, the metal joint is disposed at a position closer to the center side of the flange portion than the fastening portion when viewed from above. According to the research of the inventors, the metal joint is relatively weaker (brittle) than the fastening portion. By disposing such a metal joint at the center side, the metal joint can be stably maintained, and the conduction reliability of the terminal can be improved for a long time.

[0017] In a preferred embodiment of the terminal disclosed herein, the first conductive member is substantially rectangular, and in the long side direction of the first conductive member, the center of the first conductive member is offset from the center of the flange of the second conductive member. Thus, when a plurality of batteries are electrically connected to each other via a bus bar, it is easy to attach the bus bar to the first conductive member, and the conduction reliability of the battery pack can be improved.

[0018] In a preferred embodiment of the terminal disclosed herein, the fastening portion is provided on one surface of the first conductive member, and the metal joint portion is provided on the other surface of the first conductive member. This can further improve the conduction reliability of the terminal.

[0019] Furthermore, according to the present invention, a secondary battery including the above-mentioned terminal is provided, thereby making it possible to improve the reliability of the secondary battery.

[0020] In addition, according to the present invention, there is provided a method for manufacturing a terminal, comprising: a fastening step, in which the flange portions of a plate-shaped first conductive member and a second conductive member are mechanically fixed to form a fastening portion that electrically connects the first conductive member and the second conductive member; and a metal joining step, in which, after the fastening step, the flange portions of the first conductive member and the second conductive member are metal-joined at a position separated from the fastening portion to form a metal joining portion.

[0021] In the above-mentioned manufacturing method, two conductive members are connected by two connecting parts with different connection methods, namely, a fastening part and a metal joint part. As a result, even if vibration, impact, etc. are applied from the outside, the terminal is not easily deformed, and it is easy to maintain a state in which the first conductive member and the second conductive member are in close contact. In addition, by forming the metal joint part after the fastening process, a metal joint part with a stable shape can be formed with high precision. Therefore, the conductive connection between the first conductive member and the second conductive member can be stably maintained. Therefore, a terminal with improved conduction reliability can be appropriately manufactured.

[0022] In a preferred embodiment of the manufacturing method disclosed herein, the first conductive member has a recessed portion for receiving at least a portion of the flange portion of the second conductive member, and in the fastening step, the fastening portion is formed by inserting a portion of the second conductive member into the recessed portion, deforming the recessed portion of the first conductive member along the outer shape of the second conductive member, and fixing the inner wall of the recessed portion with the second conductive member. Thus, the strength of the fastening portion can be improved.

[0023] In a preferred embodiment of the manufacturing method disclosed herein, the flange portion of the second conductive member has a constricted portion that fits with the first conductive member, and in the fastening step, the first conductive member is fitted with the constricted portion of the second conductive member to form the fastening portion. Since the second conductive member has a constricted portion, even if the two conductive members are made of dissimilar metals, they can be properly fixed. In addition, the workability when forming the fastening portion can be improved.

[0024] In a preferred embodiment of the manufacturing method disclosed herein, in the metal joining step, the first conductive member and the second conductive member are welded to form a welded joint. By welding, a high-strength metal joint can be stably formed.

[0025] In a preferred embodiment of the manufacturing method disclosed herein, the metal joint is disposed at a position closer to the center of the flange than the fastening portion when viewed from above. As a result, the joint portion is less likely to shift during joining, thereby improving workability. In addition, when the metal joint is formed by welding, the welded portion is less likely to shake, thereby improving weldability.

[0026] Furthermore, according to the present invention, there is provided a method for manufacturing a secondary battery using a terminal manufactured by the above-mentioned method for manufacturing a terminal, thereby being able to appropriately manufacture a secondary battery having improved conduction reliability of the terminal. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a perspective view schematically showing a battery according to one embodiment.

[0028] Figure 2 It is along Figure 1 Schematic longitudinal cross-sectional view along line II-II.

[0029] Figure 3 It is a partial enlarged cross-sectional view schematically showing the vicinity of the negative electrode terminal.

[0030] Figure 4 It is a plan view schematically showing a negative electrode terminal according to one embodiment.

[0031] Figure 5It is a bottom view schematically showing a negative electrode terminal according to one embodiment.

[0032] Figure 6 It is a side view schematically showing a negative electrode terminal according to one embodiment.

[0033] Figure 7 is along Figure 4 A schematic longitudinal cross-sectional view along line VII-VII.

[0034] Figure 8 It is a perspective view schematically showing a battery pack according to an embodiment.

[0035] Fig. 9 It is a longitudinal sectional view schematically showing a main part of a negative electrode terminal according to a modified example.

[0036] Fig.10 It is a longitudinal sectional view schematically showing a main part of a negative electrode terminal according to a modified example.

[0037] Fig.11 It is a longitudinal sectional view schematically showing a main part of a negative electrode terminal according to a modified example. [Explanation of Reference Numerals]

[0038] 10 electrode body; 14 negative electrode lead member; 20 battery case; 24 cover; 24h terminal lead hole; 40, 140, 240, 340 negative electrode terminal; 40c rivet portion; 41, 141, 341 first conductive member; 42, 142, 242, 342 second conductive member; 43, 143, 243 fastening portion; 45, 345 metal joint portion; 100 battery. DETAILED DESCRIPTION

[0039] Hereinafter, preferred embodiments of the technology disclosed herein will be described with reference to the accompanying drawings. It should be noted that matters necessary for the implementation of the present invention other than matters specifically mentioned in this specification (for example, the general structure and manufacturing process of the battery that are not a feature of the present invention) can be grasped as design matters by those skilled in the art based on the prior art in the art. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the art.

[0040] It should be noted that in this specification, "battery" refers to the term for the entire storage device that can extract electric energy, and is a concept that includes primary batteries and secondary batteries. In addition, in this specification, "secondary battery" refers to the term for the entire storage device that can be repeatedly charged and discharged, and is a concept that includes so-called storage batteries (chemical batteries) such as lithium-ion secondary batteries and nickel-metal hydride batteries, and capacitors (physical batteries) such as double-layer capacitors.

[0041] [Battery 100]

[0042] Figure 1 It is a perspective view of the battery 100 . Figure 2 It is along Figure 1 Schematic longitudinal cross-sectional view along line II-II of FIG. In addition, in the following description, reference numerals L, R, U, and D in the drawings represent left, right, top, and bottom, and reference numerals X, Y, and Z in the drawings represent the long side direction of the battery 100, the short side direction orthogonal to the long side direction, and the up and down direction. However, these are merely directions for convenience of description and do not limit the arrangement of the battery 100 in any way.

[0043] like Figure 2 As shown, the battery 100 includes an electrode body 10, a battery case 20, a positive terminal 30 and a negative terminal 40. The battery 100 is characterized in that it includes the positive terminal 30 and / or the negative terminal 40 disclosed herein, and the other structures can be the same as before. The battery 100 is a lithium ion secondary battery. Although the illustration is omitted, the battery 100 also includes an electrolyte. The battery 100 is constructed by accommodating the electrode body 10 and the electrolyte not shown in the figure in the battery case 20.

[0044] The electrode body 10 can be the same as before, without any special restrictions. The electrode body 10 has a positive electrode and a negative electrode (not shown). The electrode body 10 is, for example, a flat wound electrode body in which a strip-shaped positive electrode and a strip-shaped negative electrode are stacked in an insulated state with a strip-shaped separator, and wound around a winding axis as the center. However, the electrode body 10 can also be a stacked electrode body in which a square (typically rectangular) positive electrode and a square (typically rectangular) negative electrode are stacked in an insulated state. The positive electrode has a positive electrode collector 11 and a positive electrode mixture layer (not shown) fixedly bonded to the positive electrode collector 11. The positive electrode collector 11 is composed of, for example, a conductive metal such as aluminum, an aluminum alloy, nickel, and stainless steel. The positive electrode mixture layer contains a positive electrode active material (such as a lithium transition metal composite oxide). The negative electrode has a negative electrode collector 12 and a negative electrode mixture layer (not shown) fixedly bonded to the negative electrode collector 12. The negative electrode current collector is made of, for example, a conductive metal such as copper, copper alloy, nickel, stainless steel, etc. The negative electrode mixture layer contains a negative electrode active material (for example, a carbon material such as graphite).

[0045] like Figure 2As shown, a stacked portion in which a positive electrode mixture layer and a negative electrode mixture layer are stacked in an insulated state is formed in the central portion of the electrode body 10 in the longitudinal direction X. On the other hand, at the left end portion in the longitudinal direction X of the electrode body 10, a portion of the positive electrode collector 11 (positive electrode collector exposed portion) on which the positive electrode mixture layer is not formed extends from the stacked portion. A positive electrode lead member 13 is attached to the positive electrode collector exposed portion. The positive electrode lead member 13 may also be made of the same metal material as the positive electrode collector 11, such as a conductive metal such as aluminum, aluminum alloy, nickel, stainless steel, etc. In addition, at the right end portion in the longitudinal direction X of the electrode body 10, a portion of the negative electrode collector 12 (negative electrode collector exposed portion) on which the negative electrode mixture layer is not formed extends from the stacked portion. A negative electrode lead member 14 is attached to the negative electrode collector exposed portion. The material (metal type) of the negative electrode lead member 14 may also be different from that of the positive electrode lead member 13. The negative electrode lead member 14 may be made of the same metal as the negative electrode current collector 12 , for example, a conductive metal such as copper, a copper alloy, nickel, or stainless steel.

[0046] The electrolyte can be the same as before, without any particular limitation. The electrolyte is, for example, a non-aqueous liquid electrolyte (non-aqueous electrolyte) containing a non-aqueous solvent and a supporting electrolyte. The non-aqueous solvent includes, for example, carbonates such as ethylene carbonate, dimethyl carbonate, and ethyl methyl carbonate. The supporting electrolyte is, for example, a fluorine-containing lithium salt such as LiPF6. However, the electrolyte can also be solid (solid electrolyte) and integrated with the electrode body 10.

[0047] The battery case 20 is a frame that contains the electrode body 10. Here, the battery case 20 is formed into a flat rectangular parallelepiped (square) with a bottom. 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 in the past, and there is no particular limitation. The battery case 20 is made of a metal material that is light in weight and has good thermal conductivity, such as aluminum, aluminum alloy, and stainless steel. Figure 2 As shown, the battery case 20 includes a case body 22 having an opening 22h and a cover (sealing plate) 24 that blocks the opening 22h. The battery case 20 is integrated by joining (for example, welding) the cover 24 to the periphery of the opening 22h of the case body 22. The battery case 20 is hermetically sealed (sealed).

[0048] The shell body 22 has a flat bottom surface 22d. The cover body 24 faces the bottom surface 22d of the shell body 22. The cover body 24 is installed on the shell body 22 in a manner to block the opening 22h of the shell body 22. The cover body 24 is generally rectangular in shape. It should be noted that in this specification, "generally rectangular" refers to a term other than a complete rectangular shape (rectangular shape), such as a shape in which the corners connecting the long sides and the short sides of the rectangular shape are rounded, a shape with a cutout at the corner, etc.

[0049] like Figure 1 As shown, the positive terminal 30 and the negative terminal 40 protrude to the outside of the battery case 20. Here, the positive terminal 30 and the negative terminal 40 protrude from the same surface of the battery case 20 (specifically, the cover 24). However, the positive terminal 30 and the negative terminal 40 may protrude from different surfaces of the battery case 20. The positive terminal 30 and the negative terminal 40 are arranged at both end portions of the cover 24 in the long side direction X. The positive terminal 30 and / or the negative terminal 40 are an example of the terminal disclosed herein.

[0050] The positive terminal 30 is electrically connected to the positive electrode of the electrode body 10 via the positive electrode lead member 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 electrode lead member 14 inside the battery case 20. The positive terminal 30 and the negative terminal 40 are respectively attached to the cover 24. The positive terminal 30 and the negative terminal 40 are respectively separated by a gasket 50 (see Figure 3 ) and insulator 60 (refer to Figure 3 ) is insulated from the cover body 24.

[0051] Figure 3 4 is a partial enlarged cross-sectional view schematically showing the vicinity of the negative terminal 40. It should be noted that the terminal structure on the negative terminal 40 side is described in detail below as an example, but the terminal structure on the positive terminal 30 side can also be the same. In this case, in the following description, the "negative electrode" can be appropriately replaced with the "positive electrode".

[0052] like Figure 3 As shown, a terminal lead-out hole 24h is formed in the cover body 24 and penetrates in the up-down direction Z. When viewed from above, the terminal lead-out hole 24h is, for example, annular (e.g., circular). The terminal lead-out hole 24h has an inner diameter large enough to allow the shaft column portion 42s of the negative terminal 40 described later before riveting to be inserted. The terminal lead-out hole 24h is formed to be smaller than the flange portion 42f of the negative terminal 40 described later.

[0053] The negative electrode lead member 14 is attached to the negative electrode collector exposed portion of the negative electrode collector 12, and constitutes a conduction path that electrically connects the negative electrode to the negative electrode terminal 40. The negative electrode lead member 14 has a flat plate-shaped portion 14f that extends horizontally along the inner surface of the cover 24. A through hole 14h is formed in the flat plate-shaped portion 14f at a position corresponding to the terminal lead hole 24h. The through hole 14h has an inner diameter of a size that allows the shaft column portion 42s of the negative terminal 40 described later to be inserted before the riveting process. The negative electrode lead member 14 is fixed to the cover 24 by riveting in an insulated state via the insulator 60.

[0054] The gasket 50 is an insulating member disposed between the upper surface (outer surface) of the cover 24 and the negative electrode terminal 40. Here, the gasket 50 has the function of insulating the cover 24 from the negative electrode terminal 40 and sealing the terminal lead-out hole 24h. The gasket 50 is made of an electrically insulating and elastically deformable resin material, such as a fluorinated resin such as a perfluoroalkoxy fluorine resin (PFA), a polyphenylene sulfide resin (PPS), an aliphatic polyamide, and the like.

[0055] The gasket 50 has a barrel 51 and a base 52. The barrel 51 is a part that prevents direct contact between the cover 24 and the shaft column portion 42s of the negative terminal 40. The barrel 51 is a hollow cylindrical shape. The barrel 51 has a through hole 51h that penetrates in the up-down direction Z. The through hole 51h is formed so that the shaft column portion 42s of the negative terminal 40 before the riveting process can be inserted. The barrel 51 is inserted into the terminal lead-out hole 24h of the cover 24. The base 52 is a part that prevents direct contact between the cover 24 and the flange portion 42f of the negative terminal 40 described later. The base 52 is connected to the upper end of the barrel 51. The base 52 extends in the horizontal direction from the upper end of the barrel 51. The base 52 is formed in a circular ring shape, for example, in a manner that surrounds the terminal lead-out hole 24h of the cover 24. The base 52 extends along the upper surface of the cover 24. The base portion 52 is sandwiched between the lower surface 42 d of the flange portion 42 f of the negative electrode terminal 40 and the upper surface of the lid 24 , and is compressed in the up-down direction Z by caulking.

[0056] The insulator 60 is an insulating member disposed between the lower surface (inner surface) of the cover 24 and the negative lead member 14. The insulator 60 has a function of insulating the cover 24 from the negative lead member 14. The insulator 60 has a flat plate-shaped portion extending horizontally along the inner surface of the cover 24. A through hole 60h is formed in the flat plate-shaped portion at a position corresponding to the terminal lead hole 24h. The through hole 60h has an inner diameter of a size through which the shaft column portion 42s of the negative terminal 40 can be inserted. The insulator 60 has resistance to the electrolyte used and electrical insulation, and is made of an elastically deformable resin material, such as a fluorinated resin such as a perfluoroalkoxy fluorine resin (PFA), a polyphenylene sulfide resin (PPS), or the like. The flat plate-shaped portion of the insulator 60 is sandwiched between the lower surface of the cover 24 and the upper surface of the negative lead member 14, and is compressed in the vertical direction Z by riveting.

[0057] [Negative terminal 40]

[0058] The negative terminal 40 is inserted through the terminal lead-out hole 24h and extends from the inside of the battery case 20 to the outside. As described later, the negative terminal 40 is composed of two conductive members, namely, a first conductive member 41 and a second conductive member 42, which are integrated by a fastening portion 43 and a metal joint portion 45. Figure 3As shown, the negative terminal 40 is riveted to the peripheral portion of the cover 24 surrounding the terminal lead-out hole 24h in a state insulated from the cover 24 by riveting. A rivet portion 40c is formed at the lower end of the negative terminal 40. The negative terminal 40 is fixed to the cover 24 by riveting and is electrically connected to the negative lead member 14.

[0059] Figure 4~Figure 6 They are schematic diagrams of the negative terminal 40 before being installed on the cover 24 (ie, before riveting), Figure 4 It is a top view. Figure 5 This is a bottom view. Figure 6 is a side view. In addition, Figure 7 It is along Figure 4 The schematic longitudinal cross-sectional view taken along line VII-VII of FIG. 4 is a schematic longitudinal cross-sectional view showing a main part of the negative electrode terminal 40. Figure 7 As shown, the negative electrode terminal 40 includes a first conductive member 41, a second conductive member 42, a fastening portion 43, and a metal joint portion 45. The first conductive member 41 and the second conductive member 42 are integrated via the fastening portion 43 and the metal joint portion 45 and are electrically connected to each other.

[0060] The first conductive member 41 is a member disposed outside the battery case 20. The first conductive member 41 is made of metal. The first conductive member 41 is made of conductive metal such as aluminum, aluminum alloy, nickel, stainless steel, etc. The first conductive member 41 is made of aluminum. The first conductive member 41 may also be the same metal as the positive electrode lead member 13, or an alloy having the same metal element as the first component (the component with the highest proportion in terms of mass ratio, the same below). Figure 4~Figure 6 As shown, the first conductive member 41 is plate-shaped. The first conductive member 41 is in the shape of a flat plate. The first conductive member 41 has a lower surface 41d and an upper surface 41u. The lower surface 41d is the surface on the side facing the battery case 20 (specifically, the cover body 24). The upper surface 41u is the surface on the side away from the battery case 20. In the technology disclosed herein, the lower surface is an example of "one surface" and the upper surface is an example of "the other surface". Here, the first conductive member 41 is roughly rectangular. The first conductive member 41 is divided into two parts in the long side direction X, and has a connecting portion 41a electrically connected to the second conductive member 42 and a side ( Figures 4 to 6 An extension portion 41b extending to the left of the device.

[0061] like Figure 7 As shown, the connecting portion 41a has a thin-walled portion 41t (see also Figure 4), which is formed to be thinner than the extension portion 41b; a through hole 41h, which penetrates in the up-down direction Z; and a recess 41r, which is recessed from the lower surface 41d of the first conductive member 41. The thin-walled portion 41t is provided with a metal joint portion 45. Figure 4 As shown, the thin-walled portion 41t is formed in an annular shape (e.g., annular shape) when viewed from above. The through hole 41h is formed in an annular shape (e.g., annular shape) when viewed from above. 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 from the through hole 41h. Figure 7 As shown, the through hole 41h is provided in the central part of the thin-walled portion 41t. The through hole 41h is provided at a position closer to the inner peripheral side than the fastening portion 43 and the metal joint portion 45. The through hole 41h can function as a discharge channel for gas and heat generated during welding. The recess 41r is provided at a position closer to the outer peripheral side than the metal joint portion 45. Although the illustration is omitted, the recess 41r is formed in an annular shape (e.g., a circular ring shape) when viewed from above. Here, the recess 41r is formed in a tapered shape that decreases in diameter toward the lower surface 41d of the first conductive member 41 (in other words, the closer to the second conductive member 42). The constricted portion 42n of the second conductive member 42 described later is inserted into the recess 41r.

[0062] The extension portion 41 b is used, for example, to electrically connect a plurality of batteries 100 to form a battery pack 200 (see Figure 8 ) is provided with a bus bar 90 as a conductive member (see Figure 8 ) part. By having the extension portion 41b, the grounding area with the bus bar 90 can be sufficiently ensured, and the conduction reliability of the battery pack 200 can be improved. Figure 4 , Figure 5 As shown, the first conductive member 41 has the extending portion 41 b , so that the center position 41 c thereof is offset to the right in the longitudinal direction X from the center position 42 c of the second conductive member 42 (specifically, the center position of a flange portion 42 f described later).

[0063] The second conductive member 42 is a member extending from the inside to the outside of the battery case 20. The second conductive member 42 is made of metal. The second conductive member 42 is composed of, for example, conductive metals such as copper, copper alloys, nickel, and stainless steel. The material of the second conductive member 42, such as the first component, may be the same as or different from that of the first conductive member 41. Here, the second conductive member 42 is composed of a metal having a higher hardness than the first conductive member 41. The second conductive member 42 is made of copper. The second conductive member 42 may also be the same metal as the negative electrode lead member 14 or an alloy having the same metal element as the first component. The second conductive member 42 may also have a metal covering portion covered with a metal such as Ni on a part or all of the surface. This can improve the tolerance to the electrolyte and improve the corrosion resistance. Figure 6 , Figure 7 As shown, the second conductive member 42 has an axis C. The second conductive member 42 has a flange portion 42 f electrically connected to the first conductive member 41 and a shaft column portion 42 s connected to the lower end of the flange portion 42 f.

[0064] The outer shape of the flange portion 42f is larger than that of the shaft column portion 42s. Figure 3 As shown in FIG. 1 , the outer shape of the flange portion 42f is larger than the terminal lead-out hole 24h of the cover body 24. The flange portion 42f is a portion that protrudes from the terminal lead-out hole 24h of the cover body 24 to the outside of the battery case 20. Figure 5~Figure 7 As shown, the outer shape of the flange portion 42f is generally cylindrical. Figure 6 , Figure 7 As shown in FIG. 4 , the axis of the flange portion 42f coincides with the axis C of the second conductive member 42. Figure 7 As shown, the flange portion 42f has a lower surface 42d, a side surface (outer peripheral surface) 42o extending upward from the lower surface 42d, and a constricted portion 42n formed by constricting a portion of the side surface 42o.

[0065] The constricted portion 42n is continuously or intermittently provided on a portion of the side surface 42o of the flange portion 42f. Although not shown in the figure, the constricted portion 42n is formed in an annular shape (e.g., a circular ring shape) when viewed from above. When the constricted portion 42n is formed in an annular shape, a high-strength fastening portion 43 can be formed. The constricted portion 42n is formed symmetrically with respect to the axis C of the flange portion 42f. The constricted portion 42n is formed in an inverted tapered shape that expands toward the upper surface 41u (in other words, the farther away from the shaft column portion 42s). The constricted portion 42n is inserted into the recess 41r of the first conductive member 41. Here, the constricted portion 42n is embedded in the recess 41r of the first conductive member 41 and is engaged with the recess 41r. The constricted portion 42n is an example of a "portion accommodated in the recess 41r" in the technology disclosed herein.

[0066] like Figure 7 As shown in FIG. 4 , the shaft column portion 42s extends downward from the lower end portion of the flange portion 42f. Figure 5 to Figure 7 As shown, the shaft column portion 42s is cylindrical in shape. The axis of the shaft column portion 42s coincides with the axis C of the flange portion 42f. Before the riveting process, the lower end of the shaft column portion 42s, that is, the end on the opposite side of the flange portion 42f, is hollow. Figure 3 As shown, the shaft column portion 42s is a portion that is inserted into the terminal lead-out hole 24h of the cover body 24 when the negative terminal 40 is mounted on the cover body 24. The lower end portion of the shaft column portion 42s is a portion that is expanded by riveting to form a rivet portion 40c when the negative terminal 40 is mounted on the cover body 24. The shaft column portion 42s is electrically connected to the negative lead member 14 inside the battery case 20 by riveting.

[0067] The fastening portion 43 is a connecting portion that mechanically fixes the flange portion 42f of the first conductive member 41 and the second conductive member 42. Here, the fastening portion 43 is arranged at a position closer to the outer peripheral side of the flange portion 42f than the metal joint portion 45 when viewed from above. The fastening portion 43 is formed in a ring shape (e.g., a circular ring shape) when viewed from above. As a result, the strength of the fastening portion 43 can be improved, and the conduction reliability of the negative terminal 40 can be further improved. The fastening portion 43 is formed continuously here. Although not particularly limited, the fastening portion 43 is arranged on the lower surface 41d of the first conductive member 41. Specifically, the inner wall of the recess 41r of the first conductive member 41 is fixed (e.g., pressed and fixed) by the constriction 42n of the second conductive member 42. As a result, the strength of the fastening portion 43 can be improved.

[0068] The method for forming the fastening portion 43 is not particularly limited as long as it is a mechanical joint based on mechanical energy, and may be, for example, press-fitting, shrink fitting, riveting, rivet, folding, bolting, etc. In some preferred embodiments, the fastening portion 43 is a fitting portion formed by fitting the recessed portion 41r of the first conductive member 41 and the constricted portion 42n of the second conductive member 42. Thus, for example, even if the first conductive member 41 and the second conductive member 42 are made of dissimilar metals, the first conductive member 41 and the second conductive member 42 can be properly fixed. The fastening portion 43 may also be, for example, a press-fit fitting portion in which the constricted portion 42n of the second conductive member 42 is fitted into the recessed portion 41r of the first conductive member 41 by press-fitting.

[0069] The metal joint 45 is a metallurgical joint between the first conductive member 41 and the flange portion 42f of the second conductive member 42. Here, the metal joint 45 is provided on the upper surface 41u of the first conductive member 41. The metal joint 45 is provided at a position separated from the through hole 41h. The metal joint 45 is provided at a position closer to the outer peripheral side than the through hole 41h. The metal joint 45 is provided at a position separated from the fastening portion 43. The metal joint 45 can be, for example, a joint having relatively higher rigidity than the fastening portion 43.

[0070] Here, the metal joint 45 is arranged at a position closer to the inner circumference side (center side) of the flange portion 42f than the fastening portion 43 when viewed from above. Since the metal joint 45 is formed using light energy, electron energy, thermal energy, etc., it can be a joint with relatively low strength (brittle) compared to the fastening portion 43. By arranging such a metal joint 45 on the inner circumference side of the fastening portion 43, the metal joint 45 can be stably maintained, and the conduction reliability of the negative terminal 40 can be improved for a long time. Here, the metal joint 45 is arranged in the thin-walled portion 41t. As a result, less energy is required during joining, and weldability can be improved. The metal joint 45 is formed continuously or intermittently. The metal joint 45 is formed symmetrically with respect to the axis C of the flange portion 42f. The metal joint 45 is formed in a ring shape (for example, a circular ring shape) when viewed from above. As a result, the strength of the metal joint 45 can be improved, and the conduction reliability of the negative terminal 40 can be further improved.

[0071] The method for forming the metal joint 45 is not particularly limited, and may be, for example, welding, pressing, brazing, etc. In some preferred embodiments, the metal joint 45 is, for example, a welded joint formed by laser welding, electron beam welding, ultrasonic welding, resistance welding, TIG (Tungsten InertGas: tungsten inert gas) welding, etc. Thus, a high-strength metal joint 45 can be stably formed. However, the metal joint 45 may also be formed by methods other than welding, such as hot pressing, ultrasonic pressing, brazing, etc.

[0072] As described above, the negative terminal 40 includes two types of connection parts with different connection methods, namely, the fastening part 43 and the metal joint part 45. Therefore, even if vibration, impact, etc. are applied from the outside, the negative terminal 40 is not easily deformed, and it is easy to maintain the state of close contact between the first conductive member 41 and the second conductive member 42. That is, it is difficult for the first conductive member 41 and the second conductive member 42 to separate. Therefore, the conductive connection between the first conductive member 41 and the second conductive member 42 can be stably maintained, and the conductive reliability of the negative terminal 40 can be improved.

[0073] [Method of Manufacturing Negative Electrode Terminal 40]

[0074] Although not particularly limited, the negative terminal 40 can be manufactured by, for example, preparing the above-mentioned first conductive member 41 and the second conductive member 42 and typically including a fastening step and a metal bonding step in sequence. However, the order of the fastening step and the metal bonding step may be opposite or substantially simultaneous. In addition, the manufacturing method disclosed herein may further include other steps at any stage.

[0075] In the fastening process, the flange portion 42f of the first conductive member 41 and the second conductive member 42 are mechanically fixed to form a fastening portion 43. The fastening portion 43 can be formed, for example, by inserting the constricted portion 42n of the second conductive member 42 into the recessed portion 41r of the first conductive member 41, and deforming the recessed portion 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 recessed portion 41r with the second conductive member 42. Thus, the strength of the fastening portion 43 can be improved. In some preferred embodiments, the fastening portion 43 is formed by fitting the recessed portion 41r of the first conductive member 41 with the constricted portion 42n of the second conductive member 42. For example, it can be formed by horizontally pressing the constricted portion 42n of the second conductive member 42 into the recessed portion 41r of the first conductive member 41. Thus, the workability of the fastening process can be improved.

[0076] In the metal joining process, the thin-walled portion 41t of the first conductive member 41 and the flange portion 42f of the second conductive member 42 are metal-joined, that is, metallurgically joined, to form a metal joining portion 45. By performing the metal joining process after the fastening process, a metal joining portion 45 with a stable shape can be formed with high precision. The metal joining portion 45 can be formed, for example, by welding the portion where the thin-walled portion 41t of the first conductive member 41 and the flange portion 42f of the second conductive member 42 are stacked in a manner that penetrates the thin-walled portion 41t. The gas and heat generated during welding are released and diffused from the through hole 41h. Through the through hole 41h, it is possible to suppress the gas and heat from being retained between the thin-walled portion 41t and the flange portion 42f. By welding, a high-strength metal joining portion 45 can be stably formed.

[0077] In some preferred embodiments, the metal joint 45 is formed at a position closer to the inner circumference than the fastening portion 43. As a result, the joint portion is less likely to shift, and the workability of the metal joining process can be improved. In addition, when the metal joint 45 is formed by welding, the welded portion is less likely to shake, and the weldability can be improved. In addition, when welding the thin-walled portion 41t, less energy is required, and the weldability can be improved.

[0078] [Method of Manufacturing Battery 100]

[0079] The battery 100 is characterized in that the positive terminal 30 and / or the negative terminal 40 manufactured by the manufacturing method described above are used. The manufacturing process other than this can be the same as before. The battery 100 can be manufactured by, for example, preparing the electrode body 10, electrolyte, shell body 22, cover body 24, positive terminal 30 and negative terminal 40 as described above and including a mounting step and a joining step.

[0080] In the mounting process, the positive electrode terminal 30, the positive electrode lead member 13, the negative electrode terminal 40, and the negative electrode lead member 14 are mounted on the cover 24. The negative electrode terminal 40 and the negative electrode lead member 14 are, for example, Figure 3 As shown, it is fixed to the cover body 24 by riveting (caulking). The riveting is performed by clamping the gasket 50 between the negative terminal 40 and the cover body 24, and clamping the insulator 60 between the cover body 24 and the negative lead member 14. In detail, the shaft column portion 42s of the negative terminal 40 before riveting is passed through the barrel portion 51 of the gasket 50, the terminal lead-out hole 24h of the cover body 24, the through hole 60h of the insulator 60, and the through hole 14h of the negative lead member 14 from the top of the cover body 24, and protrudes to the bottom of the cover body 24. In addition, the shaft column portion 42s protruding to the bottom of the cover body 24 is riveted in a manner that applies a compressive force relative to the up-down direction Z. As a result, at the tip portion ( Figure 3 The lower end portion of the rivet portion 40c is formed.

[0081] By such riveting processing, the base 52 of the gasket 50 and the flat plate-shaped portion of the insulator 60 are compressed, and the gasket 50, the cover 24, the insulator 60 and the negative lead member 14 are fixed to the cover 24 as a whole, and the terminal lead hole 24h is sealed. In addition, the installation method of the positive terminal 30 and the positive lead member 13 can also be the same as the above-mentioned negative terminal 40 and the negative lead member 14. The negative lead member 14 is welded to the exposed portion of the negative collector of the negative electrode 12, and the negative electrode of the electrode body 10 is electrically connected to the negative terminal 40. Similarly, the positive lead member 13 is welded to the exposed portion of the positive collector of the positive electrode 11, and the positive electrode of the electrode body 10 is electrically connected to the positive terminal 30. As a result, the cover 24, the positive terminal 30, the negative terminal 40 and the electrode body 10 are integrated.

[0082] In the joining process, the electrode body 10 integrated with the cover body 24 is accommodated in the internal space of the case body 22, and the case body 22 and the cover body 24 are sealed. The sealing can be performed by welding such as laser welding, for example. Then, a non-aqueous electrolyte is injected from an injection port not shown in the figure, and the injection port is blocked, thereby sealing the battery 100. As described above, the battery 100 can be manufactured.

[0083] The battery 100 can be used for various purposes, but can be preferably used for purposes where external forces such as vibration and impact may be applied during use. Typically, it can be preferably used as a power source (driving power source) for motors installed in various vehicles, such as cars and trucks. The type of vehicle is not particularly limited, and examples thereof include plug-in hybrid vehicles (PHVs), hybrid vehicles (HVs), electric vehicles (EVs), etc. Figure 8As shown, the battery 100 can also be preferably used as a battery pack 200 in which a plurality of batteries 100 are electrically connected to each other via a bus bar 90. In this case, the electrical connection between the plurality of batteries 100 can be performed by arranging, for example, a flat bus bar 90 between the extensions 41b of the first conductive member 41. The bus bar 90 is made of, for example, a conductive metal such as aluminum, an aluminum alloy, nickel, or stainless steel. The bus bar 90 and the extension 41b can be electrically connected by welding such as laser welding.

[0084] Several embodiments of the present invention have been described above, but the above embodiment is only an example. The present invention can also be implemented in various other ways. The present invention can be implemented based on the contents disclosed in this specification and the technical common sense in the field. The technology described in the claims includes technologies obtained by various deformations and changes to the above-mentioned exemplified embodiments. For example, part of the above-mentioned embodiment can be replaced with other deformation modes, and other deformation modes can be added to the above-mentioned embodiment. In addition, if the technical feature is not described as a necessary feature, it can also be appropriately deleted.

[0085] For example, in the above-mentioned embodiment, the fastening portion 43 is a fitting portion (for example, a press-fit fitting portion). However, the present invention is not limited thereto. The fastening portion 43 may be, for example, a caulking portion.

[0086] Fig. 9 1 is a longitudinal cross-sectional view schematically showing the main parts of the negative terminal 140 of the first modified example. The negative terminal 140 may be the same as the above-mentioned negative terminal 40 except that it includes a first conductive member 141, a second conductive member 142 and a fastening portion 143. The first conductive member 141 may be the same as the above-mentioned first conductive member 41 except that it does not have a recess 41r and has a plurality of legs 141p. The leg 141p is formed to protrude downward (on the same side as the shaft column portion 42s) from the lower surface 141d, and can be inserted through the through hole 142h of the second conductive member 142 in a state before riveting. The plurality of legs 141p are formed symmetrically with respect to the axis C of the flange portion 142f described later. The number of the legs 141p is, for example, 6. The second conductive member 142 may be the same as the above-mentioned second conductive member 42 except that the flange portion 142f having the through-holes 142h at the positions corresponding to the plurality of leg portions 141p is provided instead of the constricted portion 42n. The plurality of leg portions 141p are respectively inserted through the corresponding through-holes 142h. Fig. 9The lower end portion of the flange portion 142f is riveted. A riveted portion 141c is formed at the peripheral portion of the through hole 142h of the second conductive member 142. Here, the fastening portion 143 is the riveted portion 141c. When viewed from above, the riveted portion 141c is formed in an intermittent ring shape (for example, a circular ring shape) relative to the axis C of the flange portion 142f. As a result, the strength of the fastening portion 143 can be improved, and the workability when forming the fastening portion 143 can be improved.

[0087] For example, in the above-described embodiment, the constricted portion 42n is provided on a portion of the side surface 42o of the flange portion 42f in the second conductive member 42. However, the present invention is not limited thereto. The constricted portion 42n may be provided on the entire side surface 42o of the flange portion 42f, for example.

[0088] Fig.10 2 is a longitudinal cross-sectional view schematically showing the main part of the negative terminal 240 of the second modified example. The negative terminal 240 may be the same as the above-mentioned negative terminal 40 except that it includes a second conductive member 242 and a fastening portion 243. The second conductive member 242 may be the same as the above-mentioned second conductive member 42 except that it includes a flange portion 242f having a constricted portion 242n instead of the constricted portion 42n. The constricted portion 242n is provided on the entire side surface of the flange portion 242f. The fastening portion 243 is formed by the inner wall of the recess 41r of the first conductive member 41 being pressed and fixed by the constricted portion 242n of the second conductive member 242. The lower surface 41d of the first conductive member 41 and the lower surface 242d of the flange portion 242f of the second conductive member 242 are formed in the same plane. Thus, the negative terminal 240 can be made compact in the up-down direction Z.

[0089] For example, in the above-mentioned embodiment, the first conductive member 41 has a thin-walled portion 41t, and the metal bonding portion 45 is formed in the thin-walled portion 41t. The metal bonding portion 45 is provided at a position separated from the through hole 41h. However, this is not limited to this. The metal bonding portion 45 may be formed outside the thin-walled portion 41t, or may be formed along the outer edge of the through hole 41h.

[0090] Fig.11: is a longitudinal cross-sectional view schematically showing the main part of the negative terminal 340 of the third modified example. The negative terminal 340 may be the same as the above-mentioned negative terminal 40 except that it includes a first conductive member 341, a second conductive member 342 and a metal joint 345. The first conductive member 341 may be the same as the above-mentioned first conductive member 41 except that it does not include a thin-walled portion 41t and includes a through hole 341h instead of the through hole 41h. The length of the through hole 341h in the vertical direction Z is longer than that of the through hole 41h. The second conductive member 342 may be the same as the above-mentioned second conductive member 42 except that it includes a flange portion 342f having a convex portion 342p. The convex portion 342p is formed to protrude upward (on the side opposite to the shaft column portion 42s) from the upper surface of the flange portion 342f and can be inserted through the through hole 341h of the first conductive member 341. The convex portion 342p is inserted through the through hole 341h. The metal joint 345 is formed by continuously or discontinuously metal bonding the first conductive member 341 and the convex portion 342p of the second conductive member 342 along the outer edge of the through hole 341h. As a result, the first conductive member and the second conductive member can be better maintained in a state of close contact. In addition, the first conductive member 341 can be made into a simple shape, which can reduce the manufacturing cost of the first conductive member 341.

[0091] In addition, for example, in the above-mentioned embodiment, the negative lead member 14 is electrically connected to the negative terminal 40 by deforming the shaft column portion 42s of the negative terminal 40 and riveting. However, it is not limited to this. The method of electrically connecting the negative lead member 14 to the negative terminal 40 may be, for example, mechanical fixation other than riveting, or metal joining represented by welding, or a combination thereof. From the viewpoint of improving the reliability of the connection portion, a fastening portion for mechanically fixing the negative lead member 14 to the negative terminal 40 and a metal joining portion for continuously or intermittently metal-joining the periphery of the fastening portion may be formed at the connection portion between the negative lead member 14 and the negative terminal 40.

Claims

1. A secondary battery comprising an electrode body, a battery case and a terminal, It is characterized in that The battery housing accommodates the electrode body. The battery housing comprises a cover body, The cover body has a terminal lead-out hole, The terminal has: a plate-shaped first conductive member; A second conductive member having a flange portion electrically connected to the first conductive member and a shaft column portion connected to a lower end portion of the flange portion and having an outer size smaller than that of the flange portion; a fastening portion for mechanically fixing the flange portions of the first conductive member and the second conductive member; as well as a metal joint portion for metal-joining the flange portions of the first conductive member and the second conductive member at a position separated from the fastening portion; The flange portion of the second conductive member has a constricted portion that fits with the first conductive member. The fastening portion is a fitting portion formed by fitting the neck portion of the second conductive member and the first conductive member. The metal joint portion is provided at a position closer to the center of the flange portion than the fastening portion in a plan view. The shaft column portion is inserted into the terminal lead-out hole, An insulating member is disposed between the cover body and the surface of the flange portion facing the cover body.

2. The secondary battery according to claim 1, It is characterized in that The first conductive member has a recessed portion that receives at least a portion of the flange portion of the second conductive member. The fastening portion is configured by fixing an inner wall of the recess of the first conductive member by a portion of the second conductive member accommodated in the recess.

3. The secondary battery according to claim 1, It is characterized in that The flange portion of the second conductive member has a through hole, The first conductive member has a leg portion inserted into the through hole, The fastening portion is formed by inserting the leg portion of the first conductive member into the through hole of the second conductive member.

4. The secondary battery according to claim 3, It is characterized in that The fastening portion is a caulking portion formed by caulking the distal end of the leg portion at the peripheral edge portion of the through hole.

5. The secondary battery according to any one of claims 1 to 4, It is characterized in that The metal joint is a welding joint.

6. The secondary battery according to any one of claims 1 to 4, It is characterized in that The first conductive member is substantially rectangular in shape, In the longitudinal direction of the first conductive member, the center position of the first conductive member is offset from the center position of the flange portion of the second conductive member.

7. The secondary battery according to any one of claims 1 to 4, It is characterized in that The fastening portion is provided on one surface of the first conductive member, The metal joint is provided on the other surface of the first conductive member.

8. A method for manufacturing a secondary battery, the secondary battery comprising an electrode body, a battery case and a terminal, It is characterized in that The battery housing accommodates the electrode body. The battery housing comprises a cover body, The cover body has a terminal lead-out hole, The terminal has: a plate-shaped first conductive member; A second conductive member having a flange portion electrically connected to the first conductive member and a shaft column portion connected to a lower end portion of the flange portion and having an outer size smaller than that of the flange portion; a fastening portion for mechanically fixing the flange portions of the first conductive member and the second conductive member; as well as a metal joint portion for metal-joining the flange portions of the first conductive member and the second conductive member at a position separated from the fastening portion; The flange portion of the second conductive member has a constricted portion that fits with the first conductive member. The fastening portion is a fitting portion formed by fitting the neck portion of the second conductive member and the first conductive member. The metal joint portion is provided at a position closer to the center of the flange portion than the fastening portion in a plan view. The shaft column portion is inserted into the terminal lead-out hole, An insulating member is arranged between the surface of the flange portion facing the cover and the cover. The method for manufacturing a secondary battery includes the step of caulking the distal end of the shaft column portion with an insulating member disposed between the surface of the flange portion facing the cover body and the cover body.

9. The method for manufacturing a secondary battery according to claim 8, It is characterized in that After the flange portions of the plate-shaped first conductive member and the second conductive member are mechanically fixed to form the fastening portion that electrically connects the first conductive member and the second conductive member, the terminal metal-bonds the flange portions of the first conductive member and the second conductive member at a position separated from the fastening portion to form the metal bonding portion.

10. The method for manufacturing a secondary battery according to claim 8 or 9, It is characterized in that The metal joint is formed by welding the flange portions of the first conductive member and the second conductive member.

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