JP6184747B2 - Prismatic secondary battery - Google Patents

Description

  The present invention relates to a prismatic secondary battery used for in-vehicle applications, for example.

  In recent years, secondary batteries with large capacity (Wh) have been developed as power sources for hybrid electric vehicles and pure electric vehicles. Among them, prismatic lithium ion secondary batteries with high energy density (Wh / kg) are of particular interest. Has been.

  In a rectangular lithium ion secondary battery, a flat wound group in which a positive electrode foil coated with a positive electrode active material, a negative electrode foil coated with a negative electrode active material, and a separator for insulating each of them are rolled up, Electrically connected to the positive external terminal and the negative external terminal provided on the lid. Then, the wound group is accommodated in a battery can, the opening of the battery can is sealed and welded with a lid, an electrolytic solution is injected from a liquid injection hole provided in the lid, a liquid injection stopper is inserted, and laser welding is performed. A secondary battery is produced by sealing and welding.

  In order to connect a plurality of prismatic lithium ion secondary batteries in series to form an assembled battery, a bus bar is connected to an electrode external terminal of each battery. For example, Patent Document 1 proposes a prismatic secondary battery having a structure in which external terminals of a plurality of prismatic secondary batteries are connected by bolts with a bus bar.

  As a method of connecting the bus bar, there is a method of welding the bus bar to an external terminal in addition to the bolt connection. In the case of welding, it is necessary that the positive and negative external terminals and the bus bar be made of materials that can be welded to each other. For example, when the positive electrode external terminal is aluminum and the negative electrode external terminal is copper, it is difficult to use an aluminum bus bar because it is difficult to weld aluminum and copper.

  When the bus bar is welded to the external terminal, the external terminal is made of a clad material and can be dealt with by changing the material of the external terminal having a conversion portion clad and joined at the end face of the plate-like external terminal. For example, by using a clad material in which a copper plate and an aluminum plate are arranged on a plane and end surfaces are butted and diffusion-bonded, the base end side of the external terminal is made copper and the tip side to which the bus bar is welded is made aluminum. A bus bar made of metal can be used.

WO12 / 014510 gazette

  In the rectangular secondary battery, an external terminal and a winding group are electrically connected via a connection terminal that penetrates the battery lid, and a seal portion for sealing between the battery lid and the outer edge portion of the connection terminal. Therefore, if the bus bar is fixed to the external terminal by welding, the sealing portion may be deformed by unexpected excessive impact, vibration, etc., and the sealing performance of the battery may be impaired.

  In the case of an external terminal made of a clad material, it is necessary to determine the shape in consideration of the electric resistance of the external terminal in addition to absorbing such shock and vibration. For example, when an external terminal is provided with a narrowed portion with a reduced width or thickness to absorb shock and vibration, the material has a high electrical resistance between the distal end side and the proximal end side of the external terminal made of a clad material. If it is provided on the other side, the electrical resistance of the external terminal becomes high.

  The present invention has been made in view of the above points. The object of the present invention is to fix the external terminal without impairing the hermeticity of the battery when the bus bar is fixed to the external terminal made of a clad material by welding. It is an object of the present invention to provide a prismatic secondary battery that can keep the electrical resistance of the battery low.

  The prismatic secondary battery of the present invention that solves the above problems includes a battery can that accommodates an electrode group, a battery lid that closes an opening of the battery can, an external terminal disposed on the battery lid, and the battery. A prismatic secondary battery having a connection terminal that passes through a lid and connects between the external terminal and the electrode group, wherein the external terminal has a flat plate shape extending along the battery lid. A welded portion made of the same metal as the busbar and weldable to the busbar is provided on the distal end side, and a connection portion made of a different metal from the busbar and connected to the connection terminal is provided on the proximal end side, and the welded portion And a diffusion bonding portion in which the connection portion is diffusion-bonded, provided in the middle between the distal end side and the proximal end side, and the thickness and width of the welded portion and the connection portion are lower in the electric resistance of the material. It is characterized in that at least one narrowed portion is provided. It is set to.

  ADVANTAGE OF THE INVENTION According to this invention, when a bus-bar is fixed to an external terminal by welding, the square secondary battery which can suppress the electrical resistance of an external terminal low can be provided, without impairing the sealing performance of a battery.

1 is an external perspective view of a prismatic secondary battery according to a first embodiment. The disassembled perspective view of the square secondary battery concerning 1st Embodiment. The perspective view which expands and shows a part of electrode group. The figure which expands partially the battery lid periphery of a square secondary battery, and shows typically. The top view which shows an example of the square secondary battery concerning 1st Embodiment. BB sectional drawing of FIG. 5A. CC sectional view taken on the line of FIG. 5A. The top view which shows an example of the square secondary battery concerning 1st Embodiment. FIG. 6B is a sectional view taken along line BB in FIG. 6A. CC sectional view taken on the line of FIG. 6A. The top view which shows an example of the square secondary battery concerning 1st Embodiment. FIG. 7B is a sectional view taken along line BB in FIG. 7A. CC sectional view taken on the line of FIG. 7A. The top view which shows an example of the square secondary battery concerning 2nd Embodiment. FIG. 8B is a sectional view taken along line BB in FIG. 8A. CC sectional view taken on the line of FIG. 8A. The top view which shows an example of the square secondary battery concerning 3rd Embodiment. BB sectional drawing of FIG. 9A. CC sectional view taken on the line of FIG. 9A.

[First Embodiment]
FIG. 1 is an external perspective view of the prismatic secondary battery according to the first embodiment, and FIG. 2 is an exploded perspective view of the prismatic secondary battery according to the first embodiment.

  A prismatic secondary battery (single cell) 100A is a prismatic lithium ion secondary battery used as a power source for a hybrid vehicle, an electric vehicle, or the like. A plurality of prismatic lithium ion batteries are connected in series and used as an assembled battery. .

  The prismatic secondary battery 100A includes a battery can 101 that houses an electrode group (flat wound group) 170, a battery lid 102 that closes an opening of the battery can 101, an external terminal 141 disposed on the battery lid 102, 151 and connection terminals 142 and 152 that penetrate the battery cover 102 and electrically connect the external terminals 141 and 151 and the electrode group 170.

  The battery can 101 and the battery lid 102 are formed by subjecting a metal material such as aluminum or aluminum alloy to press working or the like. The battery can 101 has a pair of wide surfaces 101a, a pair of narrow surfaces 101b, and a bottom surface 101c, and is formed in a bottomed rectangular box shape with an upper surface opened. The bottom surface 101c has a rectangular shape, with the wide surface 101a rising from a pair of long sides and the narrow surface 101b rising from a pair of short sides.

  The battery lid 102 is made of a flat plate member having a rectangular shape, and is welded so as to close the opening of the battery can 101. That is, the battery lid 102 seals the battery can 101. A positive electrode external terminal 141 and a negative electrode external terminal 151 are disposed at positions on both ends of the battery lid 102 in the long side direction. An aluminum alloy bus bar 300 can be joined to the positive external terminal 141 and the negative external terminal 151 by welding.

  Further, a gas discharge valve 103 is disposed at a position near the center in the long side direction of the battery lid 102. The gas discharge valve 103 is formed by partially thinning the battery lid 102 by press working. The gas discharge valve 103 is formed with a cleavage groove so that a large opening is formed at the time of cleavage. The gas discharge valve 103 is heated when the square secondary battery 100A generates heat due to an abnormality such as overcharge, and when the pressure in the battery rises and reaches a predetermined pressure, the gas discharge valve 103 is opened and discharges the gas from the inside. To reduce the pressure in the battery.

In the battery lid 102, a liquid injection hole 106 a for injecting an electrolytic solution into the battery is disposed at a side position of the gas discharge valve 103. The liquid injection hole 106 a is sealed by welding the liquid injection stopper 106 b to the battery lid 102 after injecting the electrolytic solution. As the electrolytic solution, for example, a non-aqueous electrolytic solution in which a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) is dissolved in a carbonate-based organic solvent such as ethylene carbonate can be used.

  A positive electrode side terminal component 140 and a negative electrode terminal component 150 are integrally assembled with the battery lid 102 to constitute a battery lid assembly 107.

  The positive electrode side terminal component 140 includes a positive electrode external terminal 141, a positive electrode connection terminal 142, and a positive electrode current collector 180 having one end bonded to the positive electrode connection terminal 142 and the other end bonded to the positive electrode 174 of the electrode group 170. Have. The negative electrode side terminal component 150 includes a negative electrode external terminal 151, a negative electrode connection terminal 152, and a negative electrode current collector 190 having one end joined to the negative electrode connection terminal 152 and the other end joined to the negative electrode 175 of the electrode group 170. Have. The configurations of the positive external terminal 141 and the negative external terminal 151 will be described later.

  The positive electrode connection terminal 142 is integrally formed with the positive electrode external terminal 141, and the negative electrode connection terminal 152 is fixed by caulking to a separate negative electrode external terminal 151. The positive electrode connection terminal 142 and the negative electrode connection terminal 152 are inserted into a pair of through holes 102 h provided at both ends in the long side direction of the battery lid 102, and the tips protrude from the back surface side of the battery lid 102. Then, by crimping the tip of the positive electrode connection terminal 142 and the tip of the negative electrode connection terminal 152, the positive electrode external terminal 141 and the negative electrode external terminal 151 are fixed to the front surface side of the battery cover 102, and the back surface side of the battery cover 102 is fixed. A positive electrode current collector 180 and a negative electrode current collector 190 are fixed.

  The material of the positive external terminal 141, the positive connection terminal 142, and the positive current collector 180 is aluminum or an aluminum alloy. The positive external terminal 141 is electrically connected to the positive current collector 180 via the positive connection terminal 142. The material of the negative electrode connection terminal 152 and the negative electrode current collector 190 is copper or a copper alloy. The negative external terminal 151 is a clad material in which aluminum or an aluminum alloy and copper or a copper alloy are clad and joined at the end face. The negative external terminal 151 is electrically connected to the negative current collector 190 via the negative connection terminal 152.

  An insulating resin 131 is interposed between the positive electrode external terminal 141 and the negative electrode external terminal 151 and the battery cover 102 to insulate them, and a gasket 130 is provided between the positive electrode connection terminal 142, the negative electrode connection terminal 152 and the battery cover 102, respectively. Between the positive electrode current collector 180, the negative electrode current collector 190, and the battery cover 102, respectively, and an insulating member 160 is interposed for insulation. The material of the insulating resin 131, the insulating member 160, and the gasket 130 is an insulating resin such as polypropylene, polybutylene terephthalate, polyphenylene sulfide, or perfluoroalkoxy fluororesin.

  An electrode group 170 is accommodated in the battery can 101. The electrode group 170 is accommodated in the battery can 101 while being covered with an insulating case (not shown). The material of the insulating case is an insulating resin such as polypropylene. Thereby, the inner surface of the battery can 101 and the electrode group 170 are electrically insulated.

  FIG. 3 is a perspective view showing the unrolling end portion of the electrode group in an exploded manner. The configuration of the electrode group 170 will be described with reference to FIG.

  As shown in FIG. 3, the electrode group 170 that is a power storage element is formed by laminating a long positive electrode 174 and a negative electrode 175 in a flat shape around a winding axis with a separator 173 interposed therebetween. It has a structure (flat wound group).

  The positive electrode 174 includes a positive electrode foil 171 and a positive electrode active material mixture layer 176 formed by coating a positive electrode active material mixture in which a binder (binder) is mixed with a positive electrode active material on both surfaces of the positive electrode foil 171. Have The negative electrode 175 includes a negative electrode foil 172 and a negative electrode active material mixture layer 177 formed by coating a negative electrode active material mixture in which a binder (binder) is mixed with a negative electrode active material on both surfaces of the negative electrode foil 172. Have Charging / discharging is performed between the positive electrode active material and the negative electrode active material.

  The positive foil 171 is an aluminum alloy foil having a thickness of about 20 to 30 μm, and the negative foil 172 is a copper alloy foil having a thickness of about 15 to 20 μm. The material of the separator 173 is a porous polyethylene resin. The positive electrode active material is a lithium-containing transition metal double oxide such as lithium manganate, and the negative electrode active material is a carbon material such as graphite capable of reversibly occluding and releasing lithium ions.

  One end of both ends of the electrode group 170 in the width direction (winding axis direction orthogonal to the winding direction) is an uncoated portion where the positive electrode active material mixture layer 176 is not formed (exposed portion of the positive electrode foil 171). The other part is a part where an uncoated part (exposed part of the negative electrode foil 172) where the negative electrode active material mixture layer 177 is not formed is laminated. The laminated body of the positive electrode side uncoated portion and the laminated body of the negative electrode side uncoated portion are respectively ultrasonically welded with the positive electrode current collector 180 and the negative electrode current collector 190 (see FIG. 2) of the battery lid assembly 107 described above. Are joined together. After being joined by ultrasonic welding, the entire electrode group 170 is covered with an insulating case (not shown), accommodated in the battery can 101, and the battery can 101 and the battery lid 102 are sealed by laser welding.

  The positive electrode external terminal 141 is electrically connected to the positive electrode current collector 180 via the positive electrode connection terminal 142, and is electrically connected to the positive electrode 174 of the electrode group 170 via the positive electrode current collector 180. The external terminal 151 is electrically connected to the negative electrode 175 of the electrode group 170 via the negative electrode connection terminal 152 and the negative electrode current collector 190. Therefore, electric power is supplied to the external load via the positive external terminal 141 and the negative external terminal 151, or external generated power is supplied to the electrode group 170 via the positive external terminal 141 and the negative external terminal 151 for charging. .

  The assembled battery is configured by arranging a plurality of rectangular secondary batteries 100A. The plurality of prismatic secondary batteries 100A are arranged such that the wide surfaces 101a of the prismatic secondary batteries 100A adjacent to each other face each other and the positive electrode external terminals 141 and the negative electrode external terminals 151 are arranged alternately in the arrangement direction. The The bus bar 300 is bridged between the positive external terminal 141 of the prismatic secondary battery 100A arranged on one side in the arrangement direction and the negative external terminal 151 of the square secondary battery 100A arranged on the other side in the arrangement direction. Welded and electrically connected in series. The material of the bus bar 300 is the same kind of aluminum or aluminum alloy as that of the positive electrode external terminal 141.

  FIG. 4 is a diagram schematically showing the periphery of the battery lid of the rectangular secondary battery partially enlarged. FIG. 4 (a) shows a case where the bus bar is made of an aluminum alloy, and FIG. The case where a bus bar is made of a copper alloy is shown.

  As shown in FIG. 4A, the battery lid 102 is provided with a positive external terminal 141 and a negative external terminal 151 via an insulating resin 131. As described above, when a plurality of prismatic secondary batteries 100A are connected in series and used as an assembled battery, the positive electrode external terminal 141 of one prismatic secondary battery 100A and the negative electrode external of the other prismatic secondary battery 100A are used. The bus bar 300 is welded between the terminals 151.

  For example, when the positive electrode external terminal is made of aluminum or an aluminum alloy and the negative electrode external terminal is made of copper or a copper alloy, the bus bar generally has the same kind of aluminum or aluminum alloy as the positive electrode external terminal 141 in consideration of the material cost of the bus bar. Is used. For this reason, aluminum or an aluminum alloy is welded on the positive electrode side, and no particular problem occurs. On the other hand, on the negative electrode side, there is a problem because welding between different metals of copper or copper alloy and aluminum or aluminum alloy occurs.

  When the bus bar 300 is made of aluminum or an aluminum alloy, the welding problem can be solved by forming the negative electrode external terminal 151 with a clad material. That is, the cladding 151a which is the base end side (negative electrode connection terminal 152 side) of the negative electrode external terminal 151 is made of copper or copper alloy, and the welded portion 151b which is the tip side to which the bus bar 300 is welded is made of aluminum or aluminum alloy. By constituting the negative electrode external terminal 151 with the material, welding between the same metals of aluminum or aluminum alloys can be achieved, the problem of welding can be solved, and the productivity of bus bar welding can be improved.

  The negative electrode external terminal 151 is made of a clad material in which a flat plate member made of copper or a copper alloy and a flat plate member made of aluminum or an aluminum alloy are arranged on a plane and end faces are butted and diffusion bonded. The negative electrode external terminal 151 has a diffusion bonding portion 151c formed of an end surface clad in which copper or a copper alloy and aluminum or an aluminum alloy are diffusion bonded between the connection portion 151a and the welding portion 151b.

  As shown in FIG. 4B, for example, when the bus bar 310 is made of copper or a copper alloy, the welding problem can be solved by forming the positive electrode external terminal 141 with a clad material. That is, the cladding 141a which is the base end side (positive electrode connecting terminal 142 side) of the positive electrode external terminal 141 is made of aluminum or aluminum alloy, and the welded portion 141b which is the tip side to which the bus bar 310 is welded is copper or copper alloy. By constituting the positive electrode external terminal 141 with the material, welding between the same metals of copper or copper alloys is eliminated, the problem of welding can be solved, and the productivity of bus bar welding can be improved.

  The positive electrode external terminal 141 is made of a clad material in which a flat plate member made of aluminum or an aluminum alloy and a flat plate member made of copper or a copper alloy are arranged on a plane and end surfaces are butted and diffusion bonded. The positive electrode external terminal 141 includes a diffusion bonding portion 141c formed of an end surface clad in which aluminum or an aluminum alloy and copper or a copper alloy are diffusion bonded between the connection portion 141a and the welding portion 141b.

  In general, various manufacturing methods have been put into practical use for clad materials. For example, when copper or copper alloy and aluminum or aluminum alloy clad material are produced in a plate shape, copper or copper alloy and aluminum or aluminum alloy plate material are respectively used. A method of manufacturing and bonding by rolling or the like is known.

  There are various types of bonding of the diffusion bonding portion 141c. For example, a bonding mode in which a boundary surface of dissimilar metals is formed along the thickness direction of the positive electrode external terminal 141, or a transition to the thickness direction of the positive electrode external terminal 141 is made. As a result, the positive electrode external terminal 141 is moved in the extending direction of the positive electrode external terminal 141 from one side to the other side, and the boundary surface is inclined. There is a joining form in which the boundary surface is crank-shaped so that it is bent in the extending direction of 141 and then shifted again in the thickness direction of the positive external terminal 141.

Next, detailed configurations of the positive external terminal 141 and the negative external terminal 151 will be described.
5A is a plan view showing an example of the prismatic secondary battery according to the first embodiment, FIG. 5B is a cross-sectional view taken along line BB in FIG. 5A, and FIG. 5C is a cross-sectional view taken along line CC in FIG. is there.

  As shown in FIGS. 5A and 5C, the positive electrode external terminal 141 has a flat plate shape extending along the battery lid 102, and a welded portion 141 b capable of welding the bus bar 300 is provided on the distal end side. A connecting portion 141a connected to the terminal 142 is provided on the proximal end side.

  The positive external terminal 141 has a constant plate thickness and a substantially constant width and extends along the long side direction of the battery lid 102. The positive external terminal 141 and the positive connection terminal 142 are made of aluminum or an aluminum alloy, and are integrally formed in this embodiment. The positive electrode connection terminal 142 is provided so as to protrude from the connection portion 141 a of the positive electrode external terminal 141, and is inserted into the through hole 102 h of the battery lid 102 and caulked at the tip protruding toward the back surface side of the battery lid 102. 141 is fixed to the front surface side of the battery lid 102, and the positive electrode current collector 180 is fixed to the back surface side of the battery lid 102.

  An insulating resin 131 is interposed between the positive electrode external terminal 141 and the battery lid 102, and a gasket 130 is interposed between the positive electrode connection terminal 142 and the through hole 102 h of the battery lid 102, and the positive electrode current collector 180. Insulating members 160 are interposed between the battery lid 102 and the battery lid 102 to insulate the members from the battery lid 102.

  As shown by hatching in FIG. 5A, a welding surface 141g to which the bus bar 300 is welded is provided in the welded portion 141b of the positive electrode external terminal 141. And, in the connection part 141a of the positive electrode external terminal 141, the cross-sectional area of the cross section parallel to the battery thickness direction (arrow D direction in FIG. 5A) is smaller than any of the maximum cross-sectional areas of the weld part 141b and the connection part 141a. In addition, a narrowed portion 141d that is narrowed so that the width is smaller than the maximum width of any of the welded portion 141b and the connecting portion 141a is provided. The narrowed portion 141d is provided at a position between the connection terminal 142 and the welded portion 141b in the extending direction of the positive electrode external terminal 141. The narrowed portion 141d is formed by cutting out a part of the side edge of the positive electrode external terminal 141 in the width direction. In the present embodiment, the narrowed portion 141d is in the width direction and in a direction approaching each other from the side edges on both sides. Each is formed by cutting out.

  Since the positive external terminal 141 is narrowed in the width direction by the constriction 141d, the rigidity is locally low in the extending direction of the positive external terminal 141. Therefore, when stress is applied to the welded portion 141b from the welded surface 141g by the bus bar 300, the constricted portion 141d can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 300 to the connection terminal 142 and to deform the seal portion that seals the gasket 130 of the connection terminal 142, and to prevent the battery from being damaged. The constricted portion 141d can be particularly deformed so as to move the welded portion 141b in the battery thickness direction (direction of arrow D) and in the direction away from the battery lid 102, and is effective in impact and vibration transmitted from the bus bar 300. Can be absorbed into.

  As shown in FIGS. 5A and 5B, the negative electrode external terminal 151 has a flat plate shape extending along the battery lid 102, and a welded portion 151 b capable of welding the bus bar 300 is provided on the distal end side. A connection portion 151a connected to the terminal 152 is provided on the proximal end side. A diffusion bonding portion 151c, which is a diffusion bonding layer in which the welding portion 151b and the connection portion 151a are diffusion bonded, is provided between the distal end side and the proximal end side.

  The negative external terminal 151 has a shape extending along the long side direction of the battery lid 102 with a constant plate thickness and a substantially constant width. The negative external terminal 151 is made of a clad material in which different metals such as aluminum or an aluminum alloy and copper or a copper alloy are diffusion-bonded at the end faces. In other words, the negative electrode external terminal 151 is made of a plate-like member in which a plate-like member made of aluminum or an aluminum alloy and a plate-like member made of copper or a copper alloy are arranged on a plane and end surfaces are butted and diffusion bonded. In the negative electrode external terminal 151, the welded portion 151b is made of aluminum or an aluminum alloy, and the connecting portion 151a is made of copper or a copper alloy. Therefore, the welded part 151b of the negative electrode external terminal 151 can be made of the same metal as the bus bar 300, and the bus bar 300 can be easily welded to the welded part 151b of the negative electrode external terminal 151. Therefore, the bus bar 300 made of aluminum or aluminum alloy, which is less expensive than copper or copper alloy, can be used, and the product cost of the assembled battery can be reduced.

  The negative external terminal 151 is formed by opening a through hole 151h in the connection portion 151a, and is closed by inserting and crimping one end of the negative connection terminal 152, and is fixed integrally with the negative connection terminal 152. ing. The negative electrode connection terminal 152 is made of the same kind of copper or copper alloy as the connection portion 151 a of the negative electrode external terminal 151. The negative electrode connection terminal 152 is inserted into the through hole 102h of the battery lid 102 and caulked at the tip protruding toward the back surface side of the battery lid 102 to fix the negative electrode external terminal 151 to the front surface side of the battery lid 102 and to collect the negative electrode current collector. The body 190 is fixed to the back side of the battery lid 102.

  An insulating resin 131 is interposed between the negative electrode external terminal 151 and the battery cover 102, and a gasket 130 is interposed between the negative electrode connection terminal 152 and the through hole 102 h of the battery cover 102, and the negative electrode current collector 190. Insulating members 160 are interposed between the battery lid 102 and the battery lid 102 to insulate the members from the battery lid 102.

  As shown by hatching in FIG. 5A, a welding surface 151g to which the bus bar 300 is welded is provided in the welded portion 151b of the negative electrode external terminal 151. The connecting portion 151a of the negative electrode external terminal 151 has a cross-sectional area in a cross section parallel to the battery thickness direction (the arrow D direction in FIG. 5A) larger than any of the maximum cross-sectional areas of the welded portion 151b, the connecting portion 151a, and the diffusion bonding portion 151c. A narrowed portion 151d is provided so that the width is narrower than any of the maximum widths of the welded portion 151b, the connecting portion 151a, and the diffusion bonding portion 151c. The narrowed portion 151d is provided at a position between the connection terminal 152 and the diffusion bonding portion 151c in the extending direction of the negative electrode external terminal 151. The narrowed portion 151d is formed by cutting out a part of the side edge of the negative electrode external terminal 151 in the width direction. In the present embodiment, the narrowed portion 151d is in the width direction and in a direction approaching each other from the side edges on both sides. Each is formed by cutting out.

  Since the negative electrode external terminal 151 is narrowed in the width direction by the narrowed portion 151d, the rigidity is locally reduced in the extending direction of the negative electrode external terminal 151. Therefore, when stress is applied to the welded portion 151b from the welded surface 151g by the bus bar 300, the constricted portion 151d can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 300 to the connection terminal 152 and to deform the seal portion 152a that seals the gasket 130 of the connection terminal 152, and to maintain the battery hermeticity. The constricted portion 151d can be particularly deformed so as to move the welded portion 151b in the battery thickness direction (direction of arrow D) and in the direction away from the battery lid 102, and the shock and vibration transmitted from the bus bar 300 are effective. Can be absorbed into.

  The narrowed portion 151 d is preferably provided at a position closer to the connection terminal 152. As a result, the moment acting on the constricted portion 151d can be further increased and deformation can be facilitated.

  As described above, the positive electrode external terminal 141 and the negative electrode external terminal 151 have the narrow portions 141d and 151d. The narrowed portions 141d and 151d have a shape that is narrowed so that the cross-sectional area of the cross section parallel to the battery thickness direction is small. Therefore, the narrowed portions 141d and 151d are more electrically conductive than other parts having the same material in the extending direction. Resistance is high.

  Since the positive external terminal 141 is made of a single material, the electrical resistance is not affected by the position where the narrowed portion 141d is provided. On the other hand, since the negative external terminal 151 is made of a clad material of aluminum or aluminum alloy and copper or copper alloy, the constricted portion 151d is welded 151b made of aluminum or aluminum alloy and copper or copper alloy. The electrical resistance varies depending on which of the connecting portions 151a is configured.

  When comparing aluminum or an aluminum alloy with copper or a copper alloy, the electrical resistance of the material of the copper or copper alloy is lower than that of the aluminum or aluminum alloy. Therefore, when the constricted portion 151d where the electric resistance is increased is provided in the welded portion 151b made of aluminum or aluminum alloy having a higher electric resistance than copper or a copper alloy, the electric resistance of the entire negative electrode external terminal 151 is increased. As a result, the battery performance may be degraded.

  On the other hand, in the present embodiment, the welded portion 151b and the connecting portion 151a have a lower electrical resistance of the material, that is, the welded portion 151b made of aluminum or an aluminum alloy having a higher electrical resistance of the material, Since the constricted portion 151d is provided in the connecting portion 151a made of copper or a copper alloy having a low electric resistance, the degree of increase in the electric resistance of the entire negative electrode external terminal 151 due to the provision of the constricted portion 151d is suppressed as low as possible. be able to. Therefore, the electrical resistance of the negative external terminal 151 can be kept low, and the battery performance can be prevented from being deteriorated by the electrical resistance.

  In the above configuration example, the case where aluminum or an aluminum alloy is used for the welded portion 151b has been described. However, nickel, a nickel alloy, iron, or an iron alloy may be used instead of aluminum or an aluminum alloy.

  6A is a plan view showing an example of the prismatic secondary battery according to the first embodiment, FIG. 6B is a cross-sectional view taken along line BB in FIG. 6A, and FIG. 6C is a cross-sectional view taken along line CC in FIG. 6A. is there.

  In this configuration example, the negative electrode external terminal 151 is made of copper or a copper alloy, and the positive electrode external terminal 141 is made of a clad material of nickel or nickel alloy, iron or iron alloy and aluminum or aluminum alloy.

  As shown in FIGS. 6A and 6C, the positive electrode external terminal 141 includes a welded portion 141b made of nickel, nickel alloy, iron or iron alloy, a connecting portion 141a made of aluminum or aluminum alloy, a welded portion 141b, and a connected portion 141a. And a diffusion bonding portion 141c formed of an end surface clad in which nickel or a nickel alloy, iron or an iron alloy, and aluminum or an aluminum alloy are diffusion bonded.

  The width of the connecting portion 141a of the positive external terminal 141 is welded so that the cross-sectional area of the cross section parallel to the battery thickness direction is smaller than any of the maximum cross-sectional areas of the welded portion 141b, the connecting portion 141a, and the diffusion bonding portion 141c. A narrowed portion 141d is provided which is narrowed so as to be smaller than the maximum width of any of the portion 141b, the connecting portion 141a, and the diffusion bonding portion 141c.

  Therefore, when stress acts on the welded portion 141b from the bus bar 310, the narrowed portion 141d can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 310 to the connection terminal 142 and to deform the seal portion 142a that seals the gasket 130, and to prevent the battery from being damaged.

  The clad material used for the positive electrode external terminal 141 is nickel, nickel alloy, iron or iron alloy, aluminum or aluminum alloy, and aluminum or aluminum alloy is nickel, nickel alloy, iron or iron alloy. The material has a lower electrical resistance.

  In the present embodiment, the constriction is not made in the connection portion 141a made of aluminum or aluminum alloy having a low electrical resistance, but in the weld portion 141b made of nickel, nickel alloy, iron or iron alloy having a high electrical resistance. Since the portion 141d is provided, the increase in the electrical resistance of the entire positive electrode external terminal 141 due to the provision of the narrowed portion 141d can be suppressed as low as possible. Therefore, the electrical resistance of the positive external terminal 141 can be kept low, and the battery performance can be prevented from being deteriorated by the electrical resistance.

  7A is a plan view showing an example of the prismatic secondary battery according to the first embodiment, FIG. 7B is a cross-sectional view taken along line BB in FIG. 7A, and FIG. 7C is a cross-sectional view taken along line CC in FIG. 7A. is there.

  In this configuration example, the negative electrode external terminal 151 is made of copper or a copper alloy, and the positive electrode external terminal 141 is made of a clad material of copper or a copper alloy and aluminum or an aluminum alloy.

  As shown in FIGS. 7A and 7C, the positive electrode external terminal 141 includes a welded portion 141b made of copper or a copper alloy, a connecting portion 141a made of aluminum or an aluminum alloy, and a copper between the welded portion 141b and the connected portion 141a. Or it has the diffusion joining part 141c by the end surface clad with which the copper alloy and aluminum or the aluminum alloy were diffusion-joined.

  The width of the welded portion 141b of the positive electrode external terminal 141 is welded so that the cross-sectional area of the cross section parallel to the battery thickness direction is smaller than any of the maximum cross-sectional areas of the welded portion 141b, the connecting portion 141a, and the diffusion bonding portion 141c. A narrowed portion 141d is provided which is narrowed so as to be smaller than the maximum width of any of the portion 141b, the connecting portion 141a, and the diffusion bonding portion 141c. The narrowed portion 141d is provided at a position between the welding surface 141g and the diffusion bonding portion 141c in the extending direction of the positive electrode external terminal 141.

  Therefore, when stress acts on the welded portion 141b from the bus bar 310, the narrowed portion 141d can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 310 to the connection terminal 142 and to deform the seal portion 142a that seals the gasket 130, and to prevent the battery from being damaged.

  When the clad material used for the positive electrode external terminal 141 is compared with copper or copper alloy and aluminum or aluminum alloy, the electrical resistance of the material of copper or copper alloy is lower than that of aluminum or aluminum alloy. Yes.

  In the present embodiment, the constricted portion 141d is provided in the welded portion 141b made of copper or copper alloy having a low electrical resistance instead of the connecting portion 141a made of aluminum or aluminum alloy having a high electrical resistance. Therefore, the degree of increase in the electrical resistance of the entire positive electrode external terminal 141 due to the provision of the narrowed portion 141d can be suppressed as low as possible. Therefore, the electrical resistance of the positive external terminal 141 can be kept low, and the battery performance can be prevented from being deteriorated by the electrical resistance.

  In addition, since the bus bar 310 made of copper or copper alloy having a lower electrical resistance than aluminum or aluminum alloy can be used, the performance of the assembled battery can be improved.

  In the present embodiment, the narrowed portions 141d and 151d are formed by cutting out a part of the positive electrode external terminal 141 and the negative electrode external terminal 151 from both sides in the width direction, but cut out only one side in the width direction. It may be formed.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. 8A to 8C.
8A is a plan view showing an example of a prismatic secondary battery according to the second embodiment, FIG. 8B is a cross-sectional view taken along line BB in FIG. 8A, and FIG. 8C is a cross-sectional view taken along line CC in FIG. 8A. is there. The same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  What is characteristic in the present embodiment is that the constricted portion has a configuration in which the thickness of the external terminal is reduced.

  As shown in FIGS. 8A and 8C, the positive electrode external terminal 141 has a flat plate shape extending along the battery lid 102, and a welded portion 141 b capable of welding the bus bar 300 is provided on the distal end side. A connecting portion 141a connected to the terminal 142 is provided on the proximal end side.

  The positive external terminal 141 has a constant plate thickness and a substantially constant width and extends along the long side direction of the battery lid 102. The positive external terminal 141 and the positive connection terminal 142 are made of aluminum or an aluminum alloy, and are integrally formed in this embodiment.

  As shown by hatching in FIG. 8A, a welding surface 141g to which the bus bar 300 is welded is provided in the welded portion 141b of the positive electrode external terminal 141. Further, the connecting portion 141a of the positive electrode external terminal 141 has a plate thickness of the welded portion 141b so that the cross-sectional area of the cross section parallel to the battery thickness direction is smaller than any of the maximum cross-sectional areas of the welded portion 141b and the connected portion 141a. And a constricted portion 141e that is narrowed so as to be smaller than any maximum thickness of the connecting portion 141a. The narrowed portion 141e is provided at a position between the connection terminal 142 and the welded portion 141b in the extending direction of the positive electrode external terminal 141. The narrowed portion 141e is formed by denting a part of the lower surface of the positive electrode external terminal 141 in the plate thickness direction along the width direction. In the present embodiment, the narrow width portion 141e is formed on the lower surface of the positive electrode external terminal 141 in the width direction full width. It is formed by providing a concave groove that is continuous at a constant depth.

  The plate thickness of the positive external terminal 141 is narrowed by the narrowed portion 141e, and the rigidity is locally low in the extending direction of the positive external terminal 141. Therefore, when stress is applied to the welded portion 141b by the bus bar 300, the narrowed portion 141e can be preferentially deformed. Therefore, it is possible to prevent the shock and vibration from being transmitted from the bus bar 300 to the connection terminal 142 and to deform the seal portion that seals the gasket 130, and to maintain the sealed state of the battery. In particular, the narrowed portion 141e can be deformed so as to move the welded portion 141b in a direction away from the surface of the battery lid 102.

  As shown in FIGS. 8A and 8B, the negative electrode external terminal 151 has a flat plate shape extending along the battery lid 102, and a welded portion 151 b capable of welding the bus bar 300 is provided on the distal end side. A connection portion 151a connected to the terminal 152 is provided on the proximal end side.

  The negative external terminal 151 has a flat plate shape extending along the long side direction of the battery lid 102 with a constant plate thickness and a substantially constant width. The negative external terminal 151 is made of a clad material in which different metals such as aluminum or an aluminum alloy and copper or a copper alloy are diffusion-bonded at the end faces. In other words, the negative electrode external terminal 151 is made of a plate-like member in which a plate-like member made of aluminum or an aluminum alloy and a plate-like member made of copper or a copper alloy are arranged on a plane and end surfaces are butted and diffusion bonded. The negative external terminal 151 includes a welded portion 151b made of aluminum or an aluminum alloy, a connecting portion 151a made of copper or a copper alloy, and copper or a copper alloy and aluminum or an aluminum alloy between the welded portion 151b and the connected portion 151a. A diffusion bonding portion 151c is formed by the end surface clad that is diffusion bonded. As shown by hatching in FIG. 8A, a welding surface 151g to which the bus bar 300 is welded is provided in the welded portion 151b of the negative electrode external terminal 151. In the connecting portion 151a of the negative electrode external terminal 151, the cross-sectional area of the cross section parallel to the battery thickness direction (arrow D direction) is smaller than any of the maximum cross-sectional areas of the welded portion 151b, the connecting portion 151a, and the diffusion bonding portion 151c. In addition, a narrowed portion 151e is provided which is narrowed so that the plate thickness is smaller than any of the maximum plate thicknesses of the welded portion 151b, the connecting portion 151a, and the diffusion bonding portion 151c. The narrowed portion 151e is provided at a position between the connection terminal 152 and the diffusion bonding portion 151c in the extending direction of the negative electrode external terminal 151. The narrowed portion 151e is formed by denting a part of the lower surface of the negative electrode external terminal 151 in the plate thickness direction along the width direction. In this embodiment, the narrow portion 151e is formed on the lower surface of the negative electrode external terminal 151 in the width direction full width. It is formed by providing a concave groove that is continuous at a constant depth.

  The plate thickness of the negative external terminal 151 is narrowed by the constriction 151e, and the rigidity is locally reduced in the extending direction of the negative external terminal 151. Therefore, when stress is applied to the welded portion 151b from the welded surface 151g by the bus bar 300, the constricted portion 151e can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 300 to the connection terminal 152 and to deform the seal portion 152a that seals the gasket 130 of the connection terminal 152, and to maintain the sealed state of the battery. In particular, the narrowed portion 151e can be deformed so as to move the welded portion 141b in a direction away from the battery lid 102.

  As described above, the positive external terminal 141 and the negative external terminal 151 have the narrowed portions 141e and 151e. Since the narrowed portions 141e and 151e have a shape in which the plate thickness is narrowed so that the cross-sectional area of the cross section parallel to the battery thickness direction is small, the narrowed portions 141e and 151e are more than the other parts having the same material in the extending direction. The electrical resistance is high.

  In the present embodiment, since the constricted portion 151e is provided in the connecting portion 151a made of copper or a copper alloy having a low electric resistance, the electric resistance of the entire negative electrode external terminal 151 due to the provision of the constricted portion 151e. The degree of increase can be kept as low as possible. Therefore, the electrical resistance of the negative external terminal 151 can be kept low, and the battery performance can be prevented from being deteriorated by the electrical resistance.

  In the above configuration example, the case where aluminum or an aluminum alloy is used for the welded portion 151b has been described. However, nickel, a nickel alloy, iron, or an iron alloy may be used instead of aluminum or an aluminum alloy.

  Similarly to the first embodiment, the negative external terminal 151 may be made of copper or a copper alloy, and the positive external terminal 141 may be made of a clad material of copper or a copper alloy and aluminum or an aluminum alloy.

  In the present embodiment, the narrowed portions 141e and 151e are formed by providing concave portions that are continuous in a groove shape with a constant depth over the entire width in the width direction on the lower surfaces of the positive electrode external terminal 141 and the negative electrode external terminal 151. However, it may be provided on the upper surfaces of the positive electrode external terminal 141 and the negative electrode external terminal 151, or may be formed by a concave portion continuous in a broken line at a predetermined interval in the width direction.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIGS. 9A to 9C.
9A is a plan view showing an example of a prismatic secondary battery according to the third embodiment, FIG. 9B is a cross-sectional view taken along line BB in FIG. 9A, and FIG. 9C is a cross-sectional view taken along line CC in FIG. 9A. is there. The same components as those in the first and second embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

  What is characteristic in the present embodiment is that the constricted portion has a configuration in which the width and thickness of the external terminal are narrowed.

  As shown in FIGS. 9A and 9C, the positive electrode external terminal 141 has a flat plate shape extending along the battery lid 102, and a welded portion 141 b capable of welding the bus bar 300 is provided on the distal end side. A connecting portion 141a connected to the terminal 142 is provided on the proximal end side.

  The positive external terminal 141 has a constant plate thickness and a substantially constant width and extends along the long side direction of the battery lid 102. The positive external terminal 141 and the positive connection terminal 142 are made of aluminum or an aluminum alloy, and are integrally formed in this embodiment.

  The constriction parts 141d and 141e are provided in the connection part 141a of the positive electrode external terminal 141. The narrowed portions 141d and 141e are disposed at the same position in the extending direction of the positive electrode external terminal 141. The narrowed portions 141d and 141e only have to be provided in the connecting portion 141a of the positive electrode external terminal 141, and may be arranged at a predetermined interval in the extending direction.

  The positive external terminal 141 is narrowed in width and plate thickness by the narrowed portions 141d and 141e, and has a locally low rigidity in the extending direction of the positive external terminal 141. Therefore, when stress is applied to the welded portion 141b by the bus bar 300, the constricted portions 141d and 141e can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 300 to the connection terminal 142 to deform the seal portion that seals the gasket 130, and to maintain the sealing performance of the battery.

  In particular, the narrowed portions 141d and 141e can be deformed so as to move the welded portion 141b in the direction of twisting in addition to the battery thickness direction and the direction away from the battery lid 102, and the shock and vibration transmitted from the bus bar 300 Can be effectively absorbed.

  As shown in FIGS. 9A and 9B, the negative electrode external terminal 151 has a flat plate shape extending along the battery lid 102, and a welded portion 151b capable of welding the bus bar 300 is provided on the distal end side. A connection portion 151a connected to the terminal 152 is provided on the proximal end side.

  The negative external terminal 151 has a flat plate shape extending along the long side direction of the battery lid 102 with a constant plate thickness and a substantially constant width. The negative external terminal 151 is made of a clad material in which different metals such as aluminum or an aluminum alloy and copper or a copper alloy are diffusion-bonded at the end faces. In other words, the negative electrode external terminal 151 is made of a plate-like member in which a plate-like member made of aluminum or an aluminum alloy and a plate-like member made of copper or a copper alloy are arranged on a plane and end surfaces are butted and diffusion bonded. The negative external terminal 151 includes a welded portion 151b made of aluminum or an aluminum alloy, a connecting portion 151a made of copper or a copper alloy, and copper or a copper alloy and aluminum or an aluminum alloy between the welded portion 151b and the connected portion 151a. A diffusion bonding portion 151c is formed by the end surface clad that is diffusion bonded.

  The connecting portion 151a of the negative external terminal 151 is provided with constrictions 151d and 151e. The narrowed portions 151 d and 151 e are arranged at the same position in the extending direction of the negative electrode external terminal 151. The narrowed portions 151d and 151e may be provided at the connection portion 151a of the negative electrode external terminal 151, and may be arranged at a predetermined interval in the extending direction.

  The negative external terminal 151 has a shape in which the width and the plate thickness are narrowed by the narrowed portions 151d and 151e, and the rigidity is locally reduced in the extending direction of the negative external terminal 151. Therefore, when stress is applied to the welded portion 151b by the bus bar 300, the constricted portions 151d and 151e can be preferentially deformed. Therefore, it is possible to prevent the impact and vibration from being transmitted from the bus bar 300 to the connection terminal 152 and to deform the seal portion 152a that seals the gasket 130 of the connection terminal 152, and to maintain the battery hermeticity. The narrowed portions 151d and 151e can be particularly deformed so as to move the welded portion 151b in the twisting direction in addition to the battery thickness direction and the direction away from the battery lid 102, and the shock and vibration transmitted from the bus bar 300 Can be effectively absorbed.

  As described above, the positive external terminal 141 and the negative external terminal 151 have the narrowed portions 141d, 141e, 151d, and 151e. Since the narrowed portions 141d, 141e, 151d, and 151e have shapes in which the width and the plate thickness are narrowed so that the cross-sectional area of the cross section parallel to the battery thickness direction is small, the same material is used in the extending direction. The electric resistance is higher than the other parts. Since the positive external terminal 141 is made of a single material, the electrical resistance is not affected by the position where the narrowed portion 141d is provided.

  On the other hand, since the negative external terminal 151 is made of a clad material of aluminum or aluminum alloy and copper or copper alloy, the constricted portion 151d is welded 151b made of aluminum or aluminum alloy and copper or copper alloy. The electrical resistance varies depending on which of the connecting portions 151a is configured.

  In this embodiment, since the constricted portions 151d and 151e are provided in the connecting portion 151a made of copper or a copper alloy having a low electrical resistance, the negative electrode external terminal 151 as a whole by providing the constricted portions 151d and 151e. The degree of increase in electrical resistance can be suppressed as low as possible. Therefore, the electrical resistance of the negative external terminal 151 can be kept low, and the battery performance can be prevented from being deteriorated by the electrical resistance.

  In the above configuration example, the case where aluminum or an aluminum alloy is used for the welded portion 151b has been described. However, nickel, a nickel alloy, iron, or an iron alloy may be used instead of aluminum or an aluminum alloy.

  Similarly to the first embodiment, the negative external terminal 151 may be made of copper or a copper alloy, and the positive external terminal 141 may be made of a clad material of copper or a copper alloy and aluminum or an aluminum alloy.

  In the present embodiment, the narrowed portions 141d and 151d are formed by cutting out a part of the positive electrode external terminal 141 and the negative electrode external terminal 151 from both sides in the width direction, but cut out only one side in the width direction. It may be formed. In the present embodiment, the narrowed portions 141e and 151e are formed by providing concave portions that are continuous in a groove shape with a constant depth over the entire width in the width direction on the lower surfaces of the positive electrode external terminal 141 and the negative electrode external terminal 151. However, it may be provided on the upper surfaces of the positive electrode external terminal 141 and the negative electrode external terminal 151, or may be formed by a concave portion continuous in a broken line at a predetermined interval in the width direction.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. Further, a part of the configuration of an embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of an embodiment. Furthermore, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

100A prismatic secondary battery 101 battery can 101a wide surface 101b narrow surface 101c bottom surface 102 battery lid 102h through hole 103 gas discharge valve 106a liquid injection hole 106b liquid injection plug 107 battery cover assembly 130 gasket 131 insulating resin 141 positive electrode external terminal 141a Connection part 141b Welding part 141c Diffusion bonding part 141d Narrowing part 141e Narrowing part 142 Positive electrode connection terminal 142a Sealing part 151 Negative electrode external terminal 151a Connection part 151b Welding part 151c Diffusion bonding part 151d Narrowing part 151e Narrowing part 151h Through hole 152 Negative electrode connection terminal 152a Seal part 160 Insulating member 170 Electrode group (flat wound group)
171 Positive electrode foil 172 Negative electrode foil 173 Separator 174 Positive electrode 175 Negative electrode 176 Positive electrode active material mixture layer 177 Negative electrode active material mixture layer 180 Positive electrode current collector 190 Negative electrode current collector 300, 310 Bus bar

Claims (1)

A battery can that houses an electrode group; a battery lid that closes an opening of the battery can; a pair of external terminals disposed on the battery lid; the pair of external terminals that pass through the battery lid; A prismatic secondary battery having a pair of connection terminals for connecting between electrode groups,
The pair of external terminals have a flat plate shape extending along the battery lid,
Either one of the pair of external terminals is
A welded portion made of the same type of metal as the busbar and capable of welding the busbar is provided on the tip side,
A connection portion connected to the connection terminal made of a metal different from the bus bar is provided on the base end side,
A diffusion bonding portion in which the welding portion and the connection portion are diffusion-bonded is provided between the distal end side and the proximal end side,
A narrowed portion with a reduced width is provided in the welded portion and the connecting portion with a lower electrical resistance of the material ,
The one external terminal is a positive external terminal,
The weld is composed of a plate-like member made of copper or a copper alloy,
The connecting portion is constituted by a plate-like member made of aluminum or aluminum alloy,
The diffusion bonding portion is configured in a portion where the welded portion and the connection portion are arranged on a plane and end faces are butted together,
The constricted part is provided in the welded part, and is formed by cutting out a part of the welded part in the width direction .

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