Secondary battery terminal and secondary battery having the same

Abstract

Through the disclosed technology, a terminal is provided that can be welded to an external component without surface treatment of the metal part crimped by ultrasonic welding. The terminal disclosed herein is a terminal constituting either the positive or negative electrode of a secondary battery, and comprises a first plate-shaped metal component and a second metal component ultrasonically welded to the plate surface of one side of the first component. A recess is formed on the surface of the first component on the opposite side to the surface to which the second component is welded, and ultrasonic welding of the first component and the second component is achieved in the recess.

Description

Technical Field

[0001] The present invention relates to a terminal of a secondary battery, and more particularly to a terminal which is arranged at a predetermined position in a secondary battery and can conduct electricity from the inside of the cell to the outside, and a secondary battery using the terminal. Background Art

[0002] Since secondary batteries such as lithium-ion secondary batteries are lightweight and can obtain high energy density, they are widely used as portable power sources for personal computers, mobile terminals, etc., or vehicle-mounted power sources for EV (electric vehicles), HV (hybrid electric vehicles), PHV (plug-in hybrid electric vehicles), etc. In particular, since vehicle-mounted power sources require high output, it is preferable to use a battery pack in which a plurality of secondary batteries (single cells) are electrically connected to each other.

[0003] A battery pack is generally constructed by electrically connecting the positive and negative terminals of a plurality of cells via bus bars. However, when welding the bus bars to the positive and negative terminals of the cells, if the metal constituting the bus bars is different from the metal constituting the positive and negative terminals, the thermal conductivity and melting point are also different, so it is difficult to perform proper welding. In addition, electricity is generated due to the contact between water and the boundary of different types of metals, which may cause corrosion and degradation of the metals.

[0004] Therefore, Patent Document 1 discloses a battery pack, in which a positive terminal made of a different type of metal is used in order to make the metal constituting the busbar the same as the metal constituting the busbar welding portion constituting the positive terminal. The positive terminal is composed of a base with aluminum as the main body and a positive electrode external terminal with copper as the main body, and the base and the positive electrode external terminal are joined by ultrasonic bonding and riveting. As a result, the compatibility when welding the copper busbar and the positive electrode external terminal with the copper as the main body can be improved.

[0005] Patent Document 2 discloses a secondary battery in which a metal member made of the same metal as that constituting a bus bar is joined to an external terminal by ultrasonic joining.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2011-124024

[0007] Patent Document 2: Japanese Patent Application Publication No. 2016-18675

[0008] However, in the technology of either patent document 1 or patent document 2, the surface of the metal to be crimped is formed with unevenness for ultrasonic bonding, and burrs are generated at the same time. Therefore, before welding external components such as busbars to the metal surface, it is necessary to perform a surface treatment process for smoothing the unevenness formed on the metal surface and a cleaning process for the burrs. The existence of such an additional process increases the cost and manufacturing time of the secondary battery, so it is not preferred. Summary of the invention

[0009] Therefore, the present invention is completed in view of the above situation, and its main purpose is to provide a terminal, which constitutes either the positive or negative electrode of a secondary battery, and can be welded to an external component such as a bus bar without surface treatment of the metal portion crimped by ultrasonic welding. In addition, another purpose of the present invention is to provide a secondary battery and a battery pack having the terminal.

[0010] The terminal disclosed herein constitutes any one of the positive and negative electrodes of a secondary battery, wherein the terminal comprises a first plate-shaped metal component and a second metal component ultrasonically welded to the plate surface of one side of the first component, a recess is formed on the surface of the first component on the opposite side to the surface to which the second component is welded, and ultrasonic welding of the first component and the second component is achieved in the recess.

[0011] According to this structure, a terminal is provided. After a first component and a second component are joined by ultrasonic welding, burrs and bumps on the metal surface caused by the ultrasonic welding are generated in the recessed portion, so that welding of external components such as a bus bar can be performed on the plate surface with the recessed portion of the first component without surface treatment.

[0012] In a preferred embodiment of the terminal disclosed herein, welding residues generated during the ultrasonic welding are present in the recessed portion. According to this structure, a terminal is provided that can be welded to an external component such as a bus bar while welding residues generated during the ultrasonic welding are present in the recessed portion.

[0013] In a preferred embodiment of the terminal disclosed herein, the first component and the second component are made of different metals. According to this structure, a terminal is provided that can well implement welding of the first component to an external component such as a bus bar and joining of the second component to an internal terminal electrically connected to the electrode body.

[0014] In a preferred embodiment of the terminal disclosed herein, the first component is made of aluminum or an alloy mainly composed of aluminum, and the second component is made of copper or an alloy mainly composed of copper. According to this structure, a terminal is provided that can appropriately implement the joining of an external component such as a busbar made of aluminum or an alloy mainly composed of aluminum to the first component, and the joining of a negative electrode internal terminal made of copper or an alloy mainly composed of copper and electrically connected to the negative electrode to the second component.

[0015] In addition, the secondary battery disclosed herein comprises an electrode body including a positive electrode and a negative electrode, a battery case that accommodates the electrode body inside, and a positive terminal and a negative terminal electrically connected to the positive and negative electrodes in the above-mentioned electrode body, respectively, and at least one of the above-mentioned positive terminal and negative terminal includes the terminal disclosed herein.

[0016] According to this structure, a secondary battery is provided in which the positive electrode terminal and the negative electrode terminal can be well bonded to external members.

[0017] In the battery pack disclosed herein, a plurality of single cells are arranged so as to be electrically connected to each other, and the secondary battery disclosed herein is used as the plurality of single cells.

[0018] According to this structure, a battery pack is provided in which electrical connection between terminals and external components such as bus bars can be satisfactorily performed.

[0019] In addition, in a preferred embodiment of the battery pack disclosed herein, among the above-mentioned multiple single cells, the positive terminal of one single cell and the negative terminal of another single cell are respectively electrically connected through a prescribed bus bar, and here, as the terminal of either the positive terminal of the above-mentioned one single cell and the negative terminal of the above-mentioned other single cell, the terminal disclosed herein is used, and the above-mentioned bus bar is formed by the same metal as the metal of the above-mentioned first component constituting the terminal.

[0020] According to such a structure, a battery pack is provided in which the bus bar, the positive electrode terminal, and the negative electrode terminal can be welded well.

[0021] In addition, in order to achieve the above-mentioned purpose, a method for manufacturing the terminal disclosed herein is provided. That is, the method for manufacturing the terminal constituting any one of the positive and negative electrodes of the secondary battery disclosed herein is characterized in that it includes the following steps, namely: a step of preparing a plate-shaped metal first component and a metal second component; and a step of joining the second component to a plate surface of one side of the first component by ultrasonic welding, wherein a recess is formed on the plate surface of the first component on the opposite side to the surface to which the second component is welded, and the ultrasonic welding is performed in the recess.

[0022] According to the manufacturing method of such a structure, burrs generated by ultrasonic welding can be accumulated in the recessed portion, and a terminal requiring no surface treatment after ultrasonic welding can be manufactured.

[0023] In a preferred embodiment of the terminal manufacturing method disclosed herein, the first member and the second member are made of metals different from each other.

[0024] According to the manufacturing method having such a structure, it is possible to manufacture a terminal in which the first member and the external member such as the bus bar can be welded well, and the second member and the internal terminal electrically connected to the electrode body can be welded well.

[0025] In a preferred embodiment of the terminal manufacturing method disclosed herein, the first member is made of aluminum or an alloy mainly composed of aluminum, and the second member is made of copper or an alloy mainly composed of copper.

[0026] According to the manufacturing method of this structure, it is possible to manufacture a terminal that can appropriately implement the joining of external components such as bus bars composed of aluminum or an alloy mainly composed of aluminum to a first component, and the joining of a negative electrode internal terminal composed of copper or an alloy mainly composed of copper to a second component that is electrically connected to the negative electrode. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0028] Figure 2 It is a perspective view schematically showing a battery pack according to an embodiment.

[0029] Figure 3 It is a partial cross-sectional view schematically showing a secondary battery according to one embodiment.

[0030] Figure 4 yes Figure 3 IV-IV line cross-sectional view.

[0031] Figure 5 It is a cross-sectional view schematically showing the structure of a terminal according to one embodiment.

[0032] Figure 6 This is a cross-sectional view schematically showing a method for ultrasonic welding of a terminal according to an embodiment.

[0033] Figure 7 It is a cross-sectional view schematically showing a connection portion of a terminal included in a secondary battery constituting a battery pack according to an embodiment.

[0034] Description of reference numerals:

[0035] 1…Secondary battery (single cell); 10…Battery pack; 12…Separator; 14…Bus bar; 14a…Bus bar welding portion; 17…End plate; 18…Bridge member; 19…Small screw; 20…Electrode body; 21…Positive electrode; 21a…Positive electrode connecting portion; 22…Negative electrode; 22a…Negative electrode connecting portion; 23…Separator; 30…Battery case; 32…Case body; 34…Lid; 34a, 34b…Terminal insertion holes; 36…Safety valve; 40…Positive electrode terminal; 42…Interior of positive electrode Terminal; 44…positive external terminal; 50…negative terminal; 52…negative internal terminal; 52a…upper end portion; 52b…lower end portion; 54…negative external terminal; 60…gasket; 60a…barrel portion; 62…insulator; 70…terminal; 72…first component; 72a…plate surface on one side; 72b…plate surface on the other side; 73…recess; 74…recess; 74a…bottom surface; 75…burr; 76…second component; 76a…rivet portion; 80…horn; 82…measuring head. DETAILED DESCRIPTION

[0036] Hereinafter, a configuration example of a secondary battery and a battery pack having a terminal of the present embodiment is briefly described with reference to the accompanying drawings. In addition, in the following drawings, components and parts having the same function are marked with the same reference numerals for description. In addition, the dimensional relationships (length, width, thickness, etc.) in each figure do not reflect the actual dimensional relationships. In addition, matters necessary for implementing the present invention other than matters specifically mentioned in this specification can be grasped as design matters of those skilled in the art based on the prior art in the field.

[0037] In the drawings of this specification, reference numeral X indicates the width direction (of the battery), reference numeral Y indicates the thickness direction, and reference numeral Z indicates the height direction. In addition, these directions are determined for the convenience of explanation and are not intended to limit the arrangement of the battery.

[0038] In this specification, "secondary battery" generally refers to a storage device that can be repeatedly charged and discharged, and includes capacitors such as double-layer capacitors (i.e., physical batteries) in addition to so-called storage batteries (i.e., chemical batteries) such as lithium-ion secondary batteries, nickel-metal hydride batteries, and nickel-cadmium batteries. In addition, in this specification, "lithium-ion secondary battery" refers to a secondary battery that uses lithium ions as charge carriers and realizes charging and discharging by the movement of charges between positive and negative electrodes accompanied by lithium ions.

[0039] <Secondary Battery>

[0040] Figure 1 : is a perspective view schematically showing a secondary battery of this embodiment. Figure 3It is a partial cross-sectional view schematically showing a secondary battery of an embodiment. The secondary battery 1 of this embodiment includes an electrode body 20, an electrolyte (not shown), a battery case 30, a positive terminal 40, a negative terminal 50, a gasket 60 and an insulator 62. The positive terminal 40 includes a positive internal terminal 42 and a positive external terminal 44, and the negative terminal 50 includes a negative internal terminal 52 and a negative external terminal 54. Here, as this embodiment, a secondary battery 1 including a terminal 70 disclosed herein as a negative external terminal 54 is illustrated. However, this is only an example, and as other examples, a secondary battery 1 including a terminal 70 having a structure disclosed herein as a positive external terminal 44 is cited. In addition, the structure of the terminal 70 will be described later.

[0041] Figure 2 Schematic diagram of a battery pack according to this embodiment. Figure 2 As shown, a plurality of secondary batteries (single cells) 1 of a battery pack 10 are arranged in an electrically connected manner to each other, and the single cells are the secondary batteries disclosed herein. By reversing and arranging the single cells 1 one by one, the positive terminal 40 and the negative terminal 50 are arranged in an alternating manner. An insulator 12 is sandwiched between the arranged single cells 1. The insulator 12 can function as a heat dissipation unit, a length adjustment unit, etc. for efficiently diffusing heat. A pair of end plates (constraint plates) 17 are arranged at both ends of the arranged single cells 1. A cross beam 18 for fastening is installed in a manner of bridging between the two end plates 17. The ends of the cross beam 18 are tightened and fixed to the end plates 17 by small screws 19. Thus, the plurality of single cells 1 are constrained in a manner in which a constraint load is applied in the arrangement direction of the single cells 1.

[0042] The battery pack 10 includes a bus bar 14 that connects the external component joint portion of the positive electrode external terminal 44 of one cell 1 and the external component joint portion of the negative electrode external terminal 54 of the other cell 1 between two adjacently arranged cells 1. Thus, a conductive path is formed from the positive electrode internal terminal 42 of one cell 1 to the negative electrode internal terminal 52 of the other cell 1 via the bus bar 14 and the external terminals, and the cells 1 are electrically connected in series.

[0043] The busbar 14 is generally made of a metal with high conductivity, such as aluminum, copper, tin, nickel, or an alloy with any of these metals as the main body. In a preferred embodiment, as a terminal of either the positive terminal 40 (positive external terminal 44) of a single cell 1 and the negative terminal 50 (negative external terminal 54) of another single cell connected by the busbar 14 in the battery pack 10, a terminal 70 of the structure disclosed herein is used, and the busbar 14 is formed of the same metal as the metal of the first component 72 constituting the terminal 70. Since the busbar 14 and the first component 72 are composed of the same metal, the welding is more secure and good conduction can be achieved. It is more preferred that the busbar 14, the external component joint portion of the positive external terminal 44, and the external component joint portion of the negative external terminal 54 are composed of the same metal. For example, the positive external terminal 44 of one single cell is composed of aluminum, the negative external terminal 54 of the other single cell is the terminal 70 of the structure disclosed herein, and the first component 72 of the terminal 70 (refer to Figure 5 ) is made of aluminum, it is preferred that the bus bar 14 is made of aluminum. With this structure, the welding of the bus bar 14 and the positive external terminal 44 and the negative external terminal 54 becomes firm, and good conduction can be further achieved. In addition, this is only a preferred specific example, and the metal constituting the positive and negative external terminals and the bus bar is not limited.

[0044] Hereinafter, each element constituting the secondary battery 1 will be described.

[0045] <Battery case>

[0046] The battery case 30 is a container for housing the electrode body 20. Figure 1 As shown in FIG. 1 , the battery case 30 in this embodiment is a flat rectangular container. However, the battery case 30 may be in a box shape other than a rectangular shape (e.g., a cylindrical box shape with a bottom). The battery case 30 includes a rectangular case body 32 with an open top surface, and a plate-shaped cover 34 that closes the opening of the case body 32. Figure 3 As shown, the cover 34 is provided with a safety valve 36 for releasing the internal pressure when the internal pressure in the battery case 30 rises to a predetermined level or more. In addition, the cover 34 is provided with a terminal insertion hole 34a for inserting the negative electrode external terminal 54, and a terminal insertion hole 34b for inserting the positive electrode external terminal 44. As the material of the battery case 30, a metal material having a required strength is used, for example, a metal material that is light and has good thermal conductivity, such as aluminum, stainless steel, and nickel-plated steel, is used.

[0047] <Electrode body>

[0048] The electrode body 20 is a power generation element contained in the battery case 30 in a state covered by an insulating film (not shown). The electrode body 20 in the present embodiment includes a positive electrode 21 in the form of a long sheet, a negative electrode 22 in the form of a long sheet, and a separator 23 in the form of a long sheet. The electrode body 20 is a wound electrode body in which the above-mentioned long sheet-like components are wound and overlapped. In addition, the structure of the electrode body is not particularly limited, and various structures that can be used in general sealed batteries can be adopted without restriction. For example, the electrode body can also be a stacked electrode body in which rectangular sheet-shaped positive and negative electrodes are stacked via a separator.

[0049] The positive electrode 21 includes a foil-shaped positive electrode current collector (e.g., aluminum foil) and a positive electrode active material layer formed on the surface (preferably on both surfaces) of the positive electrode current collector. Figure 3 The positive electrode active material layer is not formed with a positive electrode active material layer, but a positive electrode connection portion 21a where the positive electrode current collector is exposed is formed. In addition, the positive electrode active material layer contains various materials such as a positive electrode active material, a binder, and a conductive material. For the materials contained in the positive electrode active material layer, materials that can be used in existing general secondary batteries (such as lithium-ion secondary batteries) can be used without particular restrictions. Since the present invention is not limited, detailed description is omitted.

[0050] The negative electrode 22 includes a foil-shaped negative electrode current collector (e.g., copper foil) and a negative electrode active material layer formed on the surface (preferably on both surfaces) of the negative electrode current collector. Figure 3 The negative electrode active material layer is not formed with the negative electrode active material layer, but a negative electrode connection portion 22a where the negative electrode current collector is exposed is formed. In addition, similar to the positive electrode active material layer, the negative electrode active material layer also contains various materials such as negative electrode active material and binder. For the materials contained in the negative electrode active material layer, materials that can be used in existing general secondary batteries can also be used without special restrictions. Since the present invention is not limited, detailed description is omitted.

[0051] The separator 23 is sandwiched between the positive electrode 21 and the negative electrode 22 to prevent the electrodes from directly contacting each other. Although not shown in the figure, the separator 23 is formed with a plurality of micropores, and lithium ions move between the positive electrode 21 and the negative electrode 22 through the micropores. For the separator 23, a resin sheet having the required heat resistance is used, but a material that can be used in an existing general secondary battery can be used without particular limitation, so a detailed description is omitted.

[0052] The electrolyte (not shown) contained in the battery case 30 can be any electrolyte that can be used in existing general secondary batteries without particular restrictions. For example, the electrolyte can be a non-aqueous liquid electrolyte (non-aqueous electrolyte) containing a non-aqueous solvent and a carrier salt. Since this is not limited to the present invention, a detailed description is omitted.

[0053] <Electrode Terminal>

[0054] The negative terminal 50 includes a current collector terminal (negative internal terminal 52) on the negative electrode side and an external connection terminal (negative external terminal 54) on the negative electrode side. The negative internal terminal 52 is a long metal component extending in the height direction Z. Figure 3 as well as Figure 4 As shown, the lower end 52b of the negative internal terminal 52 is joined to the negative electrode 22 (specifically, the negative electrode connection portion 22a) in the battery case 30 and is electrically connected. In addition, the negative external terminal 54 is inserted through the terminal insertion hole 34a provided in the cover 34, a part of which is exposed outside the battery case 30, and the other part is electrically connected to the upper end 52a of the negative internal terminal 52 in the battery case 30. A through hole for inserting the negative external terminal 54 is provided in the upper end 52a, and after the rivet portion provided by the negative external terminal 54 is made to protrude from the through hole, the rivet portion is rivet-processed, thereby achieving the electrical connection between the negative internal terminal 52 and the negative external terminal 54. In order to prevent the battery case 30 (cover 34) and the negative internal terminal 52 and the negative external terminal 54 from being energized, an insulator 62 is arranged between the cover 34 and the negative internal terminal 52, and a gasket 60 is arranged between the cover 34 and the negative external terminal 54.

[0055] The positive terminal 40 has a structure substantially equivalent to the negative terminal 50 described above. That is, it is provided with a collector terminal (positive internal terminal 42) on the positive side and an external connection terminal (positive external terminal 44) on the positive side. The positive internal terminal 42 is a long metal component extending in the height direction Z. The lower end of the positive internal terminal 42 is connected to the positive electrode 21 (specifically, the positive electrode connection portion 21a) inside the battery case 30. In addition, the positive external terminal 44 is inserted through the terminal insertion hole 34b provided in the cover body 34, a part of which is exposed outside the battery case 30, and another part of which is connected to the upper end of the positive internal terminal 42 inside the battery case 30. A through hole for inserting the positive external terminal 44 is provided at the upper end, and after the rivet portion provided by the positive external terminal 44 is protruded from the through hole, the rivet portion is rivet-processed, thereby realizing the connection between the positive internal terminal 42 and the positive external terminal 44. In addition, for the positive terminal 40 in this embodiment, in order to prevent the battery case 30 (cover 34) and the positive internal terminal 42 and the positive external terminal 44 from being energized, an insulator 62 is arranged between the cover 34 and the positive internal terminal 42, and a gasket 60 is arranged between the cover 34 and the positive external terminal 44.

[0056] <Gasket>

[0057] The gasket 60 is disposed outside the battery case 30 and at the terminal insertion holes 34a and 34b provided in the cover 34, between the cover 34 and the positive external terminal 44, and between the cover 34 and the negative external terminal 54. Thus, the gasket 60 insulates the cover 34 from the positive external terminal 44 and the negative external terminal 54. The gasket 60 has a through hole through which the external terminal is inserted. Figure 7 As shown, the gasket 60 has a hollow cylindrical barrel 60a arranged along the periphery of the through hole, and a part of the external terminal is inserted through the barrel. As a result, the inner peripheral surface of the terminal insertion holes 34a, 34b provided in the cover body 34 is prevented from directly contacting the external terminal. In addition, the gasket 60 is riveted by the riveting part of the positive external terminal 44 or the negative external terminal 54 and is compressed in the height direction Z between the outer surface of the cover body 34 and the positive external terminal 44 or the negative external terminal 54. As a result, the outer surface of the cover body 34 and the positive external terminal 44 or the negative external terminal 54 can be sealed to prevent liquid and the like from leaking from the inside of the battery case 30 and moisture and the like from invading from the outside of the battery case 30.

[0058] The spacer 60 is formed of an elastically deformable insulating material, for example, a fluorinated resin such as a perfluoroalkoxyalkane resin (PFA), a polyphenylene sulfide resin (PPS), an aliphatic polyamide, or the like.

[0059] <Insulator>

[0060] The insulator 62 is disposed between the cover 34 and the positive internal terminal 42 and between the cover 34 and the negative internal terminal 52 inside the battery case 30 to insulate the cover 34 from the internal terminals. The insulator 62 has a through hole for inserting the positive external terminal 44 or the negative external terminal 54, and a part of the external terminal is inserted into the through hole. The insulator 62 is rivet-processed by the rivet portion of the positive external terminal 44 or the negative external terminal 54, and is compressed and fixed in the height direction Z between the outer surface of the cover 34 and the positive external terminal 44 or the negative external terminal 54.

[0061] The insulator 62 is formed of an elastically deformable insulating material, for example, polyphenylene sulfide resin (PPS), aliphatic polyamide, or the like.

[0062] <Terminal>

[0063] In the secondary battery 1 of the present embodiment, at least one of the positive electrode external terminal 44 and the negative electrode external terminal 54 is a terminal 70 having the structure disclosed herein. Figure 5 As shown, the terminal 70 includes a first member 72 and a second member 76. When the secondary battery 1 includes the terminal 70, at least a portion of the first member 72 is disposed outside the battery case 30, and at least a portion of the second member 76 is disposed inside the battery case 30.

[0064] The first member 72 is formed in a plate shape. One plate surface 72a of the first member 72 is ultrasonically welded to the second member 76, and a recessed portion 74 is formed on the other plate surface 72b. The first member 72 and the second member 76 are ultrasonically welded in the recessed portion 74.

[0065] One plate surface 72a of the first member 72 may also include a recess 73 for fitting with a portion of the second member 76. Figure 5 As shown, by fitting the recess 73 with a portion of the second member, the first member 72 and the second member 76 can be easily aligned during ultrasonic welding, and strong bonding by fitting can be achieved.

[0066] The recessed portion 74 is provided for ultrasonic welding of the first component 72 and the second component 76. By using the bottom surface 74a of the recessed portion 74 for ultrasonic welding, welding residue (burr) generated by the ultrasonic welding can be accumulated in the recessed portion 74. In addition, the unevenness of the metal surface generated by the ultrasonic welding is formed on the bottom surface 74a of the recessed portion. That is, it is possible to prevent the burr 75 and unevenness generated by the ultrasonic welding from being formed on the plate surface 72b on the other side other than the recessed portion 74 after the ultrasonic welding of the first component 72 and the second component 76. Therefore, the plate surface 72b on the other side can be welded to an external component (such as the bus bar 14) without performing surface treatment (such as cleaning treatment) after ultrasonic welding.

[0067] In a preferred embodiment, when the external component is welded to the other plate surface 72b, the recess 74 is closed by the external component. Figure 7 As shown, the bus bar 14 can be arranged in a manner to close the recess 74, and the bus bar 14 and the first component 72 can be welded. As a result, welding residue (burr 75) generated by ultrasonic welding can be sealed in the recess 74. That is, the external component such as the bus bar can be joined to the terminal 70 without performing a cleaning process for the burr 75 generated in the recess 74 after ultrasonic welding.

[0068] The shape of the recessed portion 74 is not particularly limited. For example, the shape of the recessed portion 74 may be a rectangular parallelepiped, hemispherical, cylindrical, triangular pyramidal, prism-shaped, etc., but the cross section of the recessed portion 74 at right angles to the plate surface 74b of the other party is preferably rectangular. That is, when the plate surface 74b of the other party is cut into a rectangular parallelepiped, cylindrical, prism-shaped, etc., the cross section can be rectangular. Thus, the terminal 70 can be provided in which the first component 72 and the second component 76 are easily ultrasonically welded at the bottom surface 74a of the recessed portion and firmly welded.

[0069] The number of recesses 74 to be formed is not particularly limited as long as it can be closed by an external member, and one or more recesses 74 may be formed. By forming a plurality of recesses 74, the number of sites for ultrasonic welding can be increased, and the bonding properties of ultrasonic welding can be improved.

[0070] The size of the recessed portion 74 to be formed is not particularly limited as long as it is within a range that can be closed by an external member.

[0071] like Figure 5 As shown, the second member 76 includes a rivet portion 76a, and by performing rivet processing on the rivet portion 76a, the terminal 70 and the positive internal terminal 42 or the negative internal terminal 52 can be electrically connected. Figure 7As shown, by inserting the second component 76 constituting the terminal 70 in the order of the barrel 60a of the gasket 60, the terminal insertion hole 34a of the cover body 34, the through hole of the insulator 62, and the through hole at the upper end of the above-mentioned internal terminal (here, the negative internal terminal 52), the rivet portion 76a is made to protrude from the through hole at the upper end of the internal terminal, and then the rivet portion 76a is riveted in a manner that applies a compressive force relative to the height direction Z, so that the gasket 60, the cover body 34, the insulator 62 and the above-mentioned internal terminal can be crimped and fixed.

[0072] A portion of the second member 76 may also have a shape that fits into the recess 73 provided in the first member 72. Although not particularly limited, for example Figure 5 As shown in the figure, the second member 76 is provided with a flange portion of a shape that fits into the recess 73 of the first member 72. The flange portion is shaped to expand outward from the shaft portion of the second member 76. As a result, it is easy to align the first member 72 and the second member 76 during ultrasonic welding. In addition, not only the joining by ultrasonic welding but also the joining by fitting is performed, so that the bonding property between the first member 72 and the second member 76 can be improved.

[0073] The first component 72 and the second component 76 are both made of a highly conductive metal, for example, aluminum, an alloy mainly composed of aluminum, copper, an alloy mainly composed of copper, etc. The first component 72 and the second component 76 may be made of the same metal or different metals, and preferably, the first component 72 and the second component 76 are made of different metals. That is, the metal constituting the second component 76 can be made of the same type as the metal constituting the internal terminal (positive internal terminal 42 or negative internal terminal 52) electrically connected to the second component 76, and the metal constituting the first component 72 can be made of the same type as the metal constituting the external component (for example, bus bar 14) electrically connected to the first component 72. Therefore, the welding reliability between the first component 72 and the external component is improved, and good conductivity and bonding are achieved between the second component 76 and the internal terminal.

[0074] In addition, in this specification, "alloys mainly composed of aluminum" refers to alloys composed of at least 70% aluminum. Other constituent elements contained in the alloy are not particularly limited, and may include silicon, iron, copper, manganese, magnesium, zinc, chromium, titanium, lead, zirconium, etc.

[0075] In addition, in this specification, "alloys mainly composed of copper" refers to alloys composed of at least 50% copper. Other constituent elements contained in the alloy are not particularly limited, and may include silicon, iron, manganese, magnesium, zinc, chromium, titanium, lead, tin, phosphorus, aluminum, nickel, cobalt, beryllium, zirconium, etc.

[0076] Among the terminals 70 in which the first component 72 and the second component 76 are made of different metals, it is still particularly preferred that the first component 72 is made of aluminum or an alloy with aluminum as the main body, and the second component 76 is made of copper or an alloy with copper as the main body. The terminal 70 of such a structure can be suitably used as the negative electrode external terminal 54. Typically, the negative electrode collector is made of copper foil, and since the negative electrode internal terminal 52 is preferably made of the same metal as the negative electrode collector, the negative electrode internal terminal 52 is made of copper. Therefore, based on the terminal 70 of the above structure, the connection between the second component 76 and the negative electrode internal terminal 52 is good. In addition, as a typical example, the positive electrode collector, the positive electrode internal terminal 42, and the positive electrode external terminal 44 are made of aluminum or an alloy with aluminum as the main body. Therefore, based on the terminal 70 of the above structure, since the first component 72 is made of aluminum or an alloy with aluminum as the main body, it is possible to further suitably join an external component made of the same type of metal as the positive electrode external terminal 44 and the negative electrode external terminal 54.

[0077] In the first component 72 and the second component 76, the plate surface 72a of one side of the first component 72 and a part of the second component 76 are joined by ultrasonic welding, and the crimping portion of the ultrasonic welding is the recessed portion 74. In a preferred embodiment, welding residues generated when ultrasonic welding are performed exist in the recessed portion 74. Thus, after ultrasonic welding, external components such as busbars can be welded to the plate surface 72b of the other side of the first component 72 without performing surface treatment. In addition, the fact that ultrasonic welding is performed in the recessed portion 74 can be confirmed by visual observation.

[0078] The following describes a method for manufacturing the terminal 70. The method for manufacturing the terminal 70 includes preparing a plate-shaped metal first member 72 and a metal second member 76, and joining the second member 76 to one plate surface 72a of the first member 72 by ultrasonic welding.

[0079] In this manufacturing method, first, a plate-shaped metal first member 72 and a metal second member 76 are prepared to constitute the terminal 70. A recess 74 is formed on the plate surface of the first member 72 opposite to the surface to which the second member 76 is welded (the other plate surface 72b).

[0080] In a preferred embodiment, the first component 72 and the second component 76 prepared here are made of different metals. As a result, the first component 72 and external components such as busbars joined to the first component 72 can be made of the same metal, thereby improving weldability. In addition, since the second component 76 and the internal terminal joined to the second component 76 can be made of the same metal, good connection can be achieved.

[0081] It is particularly preferred that the first component 72 prepared here is made of aluminum or an alloy mainly composed of aluminum, and the second component 76 is made of copper or an alloy mainly composed of copper. By using the terminal 70 manufactured using the above components as the negative electrode terminal 50 (negative electrode external terminal 54), the conduction on the negative electrode side can be improved, and the weldability with external components such as an aluminum bus bar can be improved.

[0082] Next, the second member 76 is joined to one plate surface 72a of the first member 72 by ultrasonic welding. The ultrasonic welding is performed in the recessed portion 74 to join the first member 72 and the second member 76. Figure 6 As shown, the horn 80 contacts the bottom surface 74a of the recess 74, and the measuring head 82 contacts the second component 76 in a manner that the first component 72 and the second component 76 are clamped in the height direction Z. In addition, the horn 80 is mounted on a punching machine (not shown) equipped with a vibration generator. The vibration generator is a device that applies the required vibration for ultrasonic welding to the horn 80. In addition, the shape of the crimping portion of the horn 80 is not particularly limited as long as it is a size that can enter the recess 74.

[0083] In addition, although not particularly limited, in a preferred example of the arrangement position of the measuring head 82, Figure 6 As shown, the measuring head 82 is disposed in the hollow structure of the rivet portion 76a of the second member 76. Thus, the measuring head 82 can be easily positioned.

[0084] After the horn 80 and the measuring head 82 are arranged, pressure is applied to the first component 72 and the second component 76 by a punching machine. And, in the state where the pressure is applied, ultrasonic vibration is applied to the horn 80. In addition, the pressure generated by the punching machine and the conditions of the ultrasonic vibration of the horn can be appropriately set according to the metal type and size of the first component 72 and the second component 76, the shape of the horn 80, etc. For example, the pressure is applied in the range of 80 to 1600N, the ultrasonic vibration is set to an amplitude of 20 to 80μm, a frequency of 15 to 150kHz, and the energy of the crimping portion of the horn 80 is set to 30 to 500J. As a result, ultrasonic welding in the recess 74 can be achieved, and the terminal 70 of the structure disclosed herein can be manufactured.

[0085] Although burrs 75 are generated by ultrasonic welding or unevenness is generated on the metal surface, according to this manufacturing method, welding residues (typically burrs 75) generated by ultrasonic welding and unevenness generated on the surface pressed by the horn 80 can be retained in the recessed portion 74. Therefore, the terminal 70 manufactured by this manufacturing method can be welded to external components such as a bus bar on the plate surface (the other plate surface 72b) on the opposite side of the surface to which the second component 76 is welded in the first component 72 without performing surface treatment after ultrasonic welding.

[0086] As described above, the terminal 70 manufactured by this manufacturing method may have burrs 75 formed in the recess 74, but the recess 74 is sealed by an external member, so that the secondary battery 1 and the battery pack 10 including the terminal 70 can be manufactured without the step of cleaning the burrs 75. Figure 7 As shown, the second member 76 constituting the terminal 70 is inserted through the barrel 60a of the gasket 60, the terminal insertion hole 34a of the cover 34, the through hole of the insulator 62, and the through hole of the upper end of the internal terminal (here, the negative internal terminal 52) in this order, and the rivet portion 76a is protruded from the through hole of the upper end of the internal terminal, and then the rivet portion 76a is riveted in a manner that a compressive force is applied relative to the height direction Z, and the gasket 60, the cover 34, the insulator 62, and the negative internal terminal 52 are crimped and fixed, thereby enabling the secondary battery 1 (cover 34) to be provided with the terminal 70. Furthermore, the bus bar 14 (external member) is arranged on the plate surface (the other plate surface 72b) having the recess 74 of the first member 72 so as to close the recess 74, and the bus bar 14 and the first member 72 are welded. By providing the bus bar welding portion 14a around the recess 74, the burr 75 can be closed in the recess 74. Thus, it is possible to weld the external component (eg, bus bar) and the terminal 70 without performing surface treatment after ultrasonic welding.

[0087] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The invention disclosed herein includes inventions obtained by variously modifying and changing the specific examples described above.

Claims

1. A battery pack is formed by arranging a plurality of single cells in an electrically connected manner. The battery pack is characterized in that A secondary battery is provided as the plurality of single batteries, The secondary battery has: An electrode body, comprising a positive electrode and a negative electrode; a battery case that contains the electrode body; and A positive terminal and a negative terminal, which are electrically connected to the positive and negative electrodes in the electrode body respectively, At least one of the positive electrode terminal and the negative electrode terminal includes a terminal constituting an electrode terminal for external connection, The terminal includes a first plate-shaped metal member and a second metal member ultrasonically welded to one plate surface of the first member. The one plate surface of the first member has a recess for fitting with a part of the second member. A recess is formed on a surface of the first member opposite to a surface to which the second member is welded, Implementing ultrasonic welding of the first component and the second component in the recessed portion, Among the plurality of cells, a positive electrode terminal of one cell and a negative electrode terminal of another cell are electrically connected by arranging a predetermined bus bar so as to close the recess and welding the bus bar to the first member.

2. The battery pack according to claim 1, characterized in that: The recessed portion contains welding residue generated when the ultrasonic welding is performed.

3. The battery pack according to claim 1 or 2, characterized in that: The first member and the second member are made of metals different from each other.

4. The battery pack according to claim 3, characterized in that: The first member is made of aluminum or an alloy mainly composed of aluminum, and the second member is made of copper or an alloy mainly composed of copper.

5. The battery pack according to claim 1, characterized in that: The terminal is used as one of the positive electrode terminal of the one cell and the negative electrode terminal of the other cell, and the bus bar is formed of the same metal as the first member constituting the terminal.

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