JP5628127B2 - Secondary battery - Google Patents

Description

  The present invention relates to a secondary battery, and more particularly to a high-capacity lithium ion secondary battery.

  In recent years, development of large-capacity prismatic lithium secondary batteries as power sources for hybrid vehicles and electric vehicles has been promoted.

  In a rectangular lithium secondary battery, a positive electrode foil in which a positive electrode active material mixture layer is formed, a negative electrode foil in which a negative electrode active material mixture layer is formed, and a flat shape in which a separator for insulating each of them is overlapped and wound The electricity storage element is electrically connected to a positive terminal and a negative terminal provided on the lid of the battery can. Then, the storage element is accommodated in the battery can, the opening of the battery can is sealed and welded with a lid, the electrolytic solution is injected from the injection port provided in the lid, and the injection stopper is inserted into the injection port. Then, a secondary battery is manufactured by sealing welding by laser welding.

  In addition, in order to connect a plurality of the rectangular secondary batteries described above in series to form an assembled battery, one end of the bus bar is fastened with a nut to a bolt provided on the positive electrode terminal of the secondary battery, and the other end of the bus bar is fixed. The electrode terminals of the adjacent secondary batteries are electrically connected by being fastened and fixed to the bolt provided on the negative electrode terminal of the adjacent secondary battery with a nut.

  By the way, since the electrode terminal of a secondary battery needs to have tolerance with respect to electrolyte solution, generally the metal material with low electrical resistance, such as aluminum and copper, is employ | adopted as the forming material. However, metal materials such as aluminum and copper have low material strength, and when tightening a nut to a bolt provided on an electrode terminal made of aluminum or copper, the bolt may be damaged if the tightening torque is excessive. There is.

  With respect to such a problem, Patent Document 1 discloses a conventional secondary battery in which a bus bar can be easily clamped and fixed to a bolt of an electrode terminal.

  In the secondary battery disclosed in Patent Document 1, a portion (connection terminal) connected to the storage element of the positive electrode terminal is made of aluminum or an aluminum alloy, and the connection terminal is connected to the outside of the battery can for bus bar connection. The bolt of the positive terminal protruded from is made of a relatively strong iron-based material compared to the connection terminal, and the connection terminal and the bolt are welded and fixed.

JP 2010-170920 A

  According to the secondary battery disclosed in Patent Document 1, the bolt of the positive terminal is made of a conductive material having a strength higher than that of a connection terminal made of aluminum or an aluminum alloy, so that the torque is relatively high. The bus bar can be easily clamped and fixed to the bolt, and the bus bar and the connection terminal can be electrically connected via the bolt and nut.

  However, in the secondary battery disclosed in Patent Document 1, since the bus bar is fastened and fixed to the bolt via the nut, the contact area between the bolt and the nut and the bus bar is reduced and the conductivity is low. Bolts and nuts are used as conduction paths, and there is a problem that connection resistance increases. In addition, since it is necessary to weld a connection terminal made of aluminum or an aluminum alloy and a bolt made of an iron-based material, it is difficult to weld both of them with high quality, and the assemblability of the secondary battery is lowered. There is.

  The present invention has been made in view of the above problems, and the object thereof is to provide a bolt made of a relatively high-strength material to fasten and fix the bus bar, and a bus bar and an electrode terminal. It is an object of the present invention to provide a secondary battery that has a low connection resistance and is easy to assemble.

  In order to solve the above-described problems, a secondary battery according to the present invention includes a connection terminal connected to an electrode of a power storage element via a current collector plate, an electrical connection to the connection terminal, and a contact with a bus bar. An external terminal having a bus bar contact surface to be contacted, and a bolt projecting from the bus bar contact surface toward the outside of the battery can in order to fasten and fix the bus bar at the bus bar contact surface of the external terminal; , And the external terminal holds the bolt made of a metal having a higher strength than the external terminal and the connection terminal.

  According to the present invention, the connection resistance between the bus bar and the connection terminal is reduced by bringing the external terminal and the bus bar into contact with each other at the bus bar contact surface provided on the external terminal to electrically connect the bus bar and the connection terminal. The secondary battery can be assembled by holding the bolt made of a relatively high-strength metal with the external terminal and fastening the bus bar with the bus bar abutting surface of the external terminal using the bolt. Can increase the sex.

  Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

1 is an overall perspective view showing the appearance of a first embodiment of a secondary battery according to the present invention. The disassembled perspective view of the secondary battery shown in FIG. The exploded perspective view of the electrical storage element (winding body) of the secondary battery shown in FIG. The perspective view which shows the cover assembly of the secondary battery shown in FIG. The expansion perspective view which expands and shows the negative electrode side of the cover assembly shown in FIG. The AA arrow directional view of the negative electrode side of the cover assembly shown in FIG. The disassembled perspective view of the negative electrode side of the lid assembly shown in FIG. The perspective view which shows the negative electrode terminal shown in FIG. The longitudinal cross-sectional view of the negative electrode terminal shown in FIG. The disassembled perspective view of the negative electrode terminal shown in FIG. The expansion perspective view which expands and shows the positive electrode side of the cover assembly shown in FIG. The BB arrow line view of the positive electrode side of the cover assembly shown in FIG. FIG. 12 is an exploded perspective view of the positive electrode side of the lid assembly shown in FIG. 11. The perspective view which shows the positive electrode terminal shown in FIG. The longitudinal cross-sectional view of the positive electrode terminal shown in FIG. The disassembled perspective view of the positive electrode terminal shown in FIG. The whole perspective view which shows the external appearance of 2nd Embodiment of the secondary battery which concerns on this invention. The enlarged perspective view which expands and shows the negative electrode side of the cover assembly of the secondary battery shown in FIG. The CC arrow line view of the negative electrode side of the cover assembly shown in FIG. The disassembled perspective view of the negative electrode side of the lid assembly shown in FIG. The disassembled perspective view of the negative electrode terminal shown in FIG.

  Hereinafter, embodiments in which a secondary battery according to the present invention is applied to a rectangular lithium ion secondary battery mounted in a hybrid vehicle or an electric vehicle will be described with reference to the drawings. Note that components having the same function are denoted by the same reference symbols throughout the drawings for describing the embodiment, and the repetitive description thereof will be omitted.

[First Embodiment]
First, with reference to FIGS. 1-16, 1st Embodiment of the secondary battery which concerns on this invention is described in detail.

  FIG. 1 shows an appearance of a first embodiment of a secondary battery according to the present invention.

  The illustrated secondary battery (lithium ion secondary battery) 500 includes a rectangular box-shaped battery can 50 having an opening (see FIG. 2) at one end, and a storage element assembly 100 housed in the battery can 50. It is roughly structured. Here, the power storage element assembly 100 has a rectangular plate-like lid 11, and the opening of the battery can 50 is welded and sealed to the lid 11 of the power storage element assembly 100. Further, the lid 11 is provided with a liquid injection hole 31 (see FIG. 2) for injecting the electrolytic solution into the battery can 50, and the electrolytic solution is injected into the battery can 50 through the liquid injection hole 31. Thereafter, a liquid injection plug 51 is inserted into the liquid injection hole 31 and sealed by laser welding so that the electrolyte does not leak outside.

  Further, the lid 11 has a negative terminal 110 composed of the bolt 1, the external terminal 4, and the connection terminal 6 (see FIG. 6), and a positive terminal 120 composed of the bolt 20, the external terminal 27, and the connection terminal 23 (see FIG. 12). It is arranged. In addition, as will be described later, the external terminal 4 and the connection terminal 6 of the negative electrode terminal 110 are integrally formed.

  A plurality of the secondary batteries 500 are arranged side by side, one end of the bus bar is fastened and fixed to the bolt 1 of the negative terminal 110 of the secondary battery 500 using a nut, and the other end of the bus bar is connected to the positive electrode of the adjacent secondary battery 500. By tightening and fixing the bolts 20 of the terminals 120 using nuts, an assembled battery in which a plurality of secondary batteries 500 are connected in series is obtained.

  FIG. 2 is an exploded view of the secondary battery 500 shown in FIG. 1, and shows a state where the current collector plate and the power storage element (winding body) are connected.

  A power storage element assembly 100 of the illustrated secondary battery 500 includes a lid assembly 32 and a wound body 45. Here, both ends in the width direction (winding axis direction) of the wound body 45 are uncoated portions (positive electrode foil) in which one end is not formed with the positive electrode active material mixture layer 41 (see FIG. 3). 40 is an area where the negative electrode active material mixture layer 44 (see FIG. 3) is not formed (the exposed area of the negative electrode foil 43). It is said that the part. Further, a positive electrode current collector plate 30 and a negative electrode current collector plate 13 are respectively provided at both ends of the lid assembly 32 in the winding axis direction downward from the lid 11. The laminate of the uncoated portion of the positive electrode foil 40 on the positive electrode side and the laminate of the uncoated portion of the negative electrode foil 43 on the negative electrode side described above are respectively the positive electrode current collector plate 30 and the negative electrode current collector plate 13 of the lid assembly 32. And are ultrasonically bonded to and connected to the positive electrode current collector plate 30 and the negative electrode current collector plate 13 by ultrasonic bonding portions 33 and 34.

  In addition, a liquid injection hole 31 for injecting an electrolytic solution into the battery can 50 is provided at a substantially central portion of the lid assembly 32.

  FIG. 3 is a partially exploded view of the power storage element (rolled body 45) of the secondary battery 500 shown in FIG. FIG. 3 shows a state before the positive electrode foil 40 and the negative electrode foil 43 of the wound body 45 are pressed and deformed to the positive electrode current collector plate 30 and the negative electrode current collector plate 13.

  The winding body 45 that is a power storage element is formed by winding the long positive electrode foil 40 and the negative electrode foil 43 in a flat shape with the separator 42 interposed therebetween, and laminating the positive electrode foil 40, the separator 42, and the negative electrode foil 43. Configured. Further, a positive electrode active material mixture layer 41 coated with a positive electrode active material mixture is formed on both surfaces of the positive electrode foil 40, and a negative electrode in which a negative electrode active material mixture is coated on both surfaces of the negative electrode foil 43. An active material mixture layer 44 is formed, and charging and discharging are performed between the positive electrode active material and the negative electrode active material.

  Here, the positive electrode foil 40 is made of an aluminum foil having a thickness of about 30 μm, the negative electrode foil 43 is made of a copper foil having a thickness of about 20 μm, and the separator 42 is made of a porous polyethylene resin. In addition, the positive electrode foil 40 is not limited to aluminum foil, For example, aluminum alloy foil may be sufficient. Moreover, the negative electrode foil 43 is not limited to copper foil, For example, copper alloy foil may be sufficient.

  FIG. 4 shows the lid assembly 32 of the secondary battery 500 shown in FIG.

  The illustrated lid assembly 32 includes a lid 11 that closes an opening (see FIG. 2) of the battery can 50, a negative terminal 110 and a positive terminal 120 that are disposed on the lid 11 via the gasket 10, and a negative terminal 110 and a positive terminal. And negative electrode current collector plate 13 and positive electrode current collector plate 30 connected to 120, respectively. Here, the negative electrode terminal 110 and the positive electrode terminal 120, the negative electrode current collector plate 13 and the positive electrode current collector plate 30 are respectively connected to the tip end portion of the shaft portion 16 (see FIG. 6) of the connection terminal 6 of the negative electrode terminal 110 and the positive electrode terminal 120. The terminal 23 is connected by caulking the tip end portion of the shaft portion 24 (see FIG. 12). Insulating sheets 12 made of resin are interposed between the negative electrode current collector plate 13 and the positive electrode current collector plate 30 and the lid 11. Thus, the negative electrode terminal 110, the positive electrode terminal 120, the negative electrode current collector plate 13, and the positive electrode current collector plate 30 are insulated from the lid 11 by the gasket 10 and the insulating sheet 12, respectively, and the lid 11 is electrically neutral. It has become.

  Next, the component configuration on the negative electrode side of the lid assembly 32 shown in FIG. 4 will be described more specifically with reference to FIGS.

  5 is an enlarged view of the negative electrode side of the lid assembly 32 shown in FIG. 4, and FIG. 6 is an AA arrow view of the negative electrode side of the lid assembly 32 shown in FIG. FIG. 6 shows a state in which one end of the bus bar B is fastened and fixed to the bolt 1 of the negative electrode terminal 110 with a nut 1A.

  As shown in FIGS. 5 and 6, the negative electrode terminal 110 is electrically connected to the connection terminal 6 that is electrically connected to the negative electrode of the wound body 45 via the negative electrode current collector plate 13 and the connection terminal 6. In order to fasten and fix the bus bar with the external terminal 4 having a substantially flat bus bar abutting surface 15 that abuts against the bus bar, and the bus bar abutting surface 15 of the external terminal 4, the battery can And a bolt 1 projecting outward from 50. Here, the external terminal 4 is disposed on the lid 11 via the gasket 10, and the bolt 1 is disposed substantially at the center of the bus bar contact surface 15 of the external terminal 4. Further, the external terminal 4 and the connection terminal 6 are integrally formed, and the shaft center L1 of the screw portion 2 of the bolt 1 and the shaft center L16 of the shaft portion 16 of the connection terminal 6 are arranged concentrically.

  Further, the bolt 1 has a truncated pyramid-shaped flange portion 3 at its base end portion, and the external terminal 4 is complementary to at least the bottom and side surfaces of the flange portion 3 in order to receive the flange portion 3 at its upper end portion. It has the receiving part 5 provided with the recessed part 7 which exhibits various shapes. Then, in a state where the flange portion 3 of the bolt 1 is disposed in the recess 7 of the external terminal 4, a portion around the flange portion 3 of the bolt 1 in the receiving portion 5 of the external terminal 4, that is, an inclined surface (upper surface) of the bolt 1. ) The portion near 9 is plastically deformed toward the inclined surface 9 to form the caulking portion 8 on the inclined surface 9 of the bolt 1, whereby the flange portion 3 of the bolt 1 is held by the receiving portion 5 of the external terminal 4. ing. During the caulking step, the bus bar contact surface 15 of the external terminal 4 is maintained substantially flat without being plastically deformed. As described above, the upper surface of the flange portion 3 of the bolt 1 is configured by the inclined surface 9 that is inclined so that the outer shape of the flange portion 3 decreases toward the outside of the battery can 50, and is caulked to the inclined surface 9. By forming the portion 8, for example, the formation of the caulking portion 8 can be simplified as compared with the case where the upper surface of the flange portion 3 is formed of a plane substantially parallel to the bottom surface.

  The external terminal 4 and the connection terminal 6 described above are resistant to the electrolytic solution, and a metal material having a low electrical resistance is selected in order to reduce the connection resistance, and the copper or copper alloy that is the same kind of metal as the negative electrode foil 43 It is composed of The bolt 1 is made of carbon steel having a strength higher than that of copper or a copper alloy in order to increase the tightening torque of the nut 1A when one end of the bus bar B is fastened and fixed to the bolt 1 using the nut 1A. It is configured.

  In addition, as shown in the figure, the gasket 10, the lid 11, the insulating sheet 12, and the negative electrode current collector plate 13 are formed by caulking the tip end portion of the shaft portion 16 of the connection terminal 6 of the negative electrode terminal 110 to form the caulking portion 14. While being clamped and fixed by the upper end part (receiving part 5) and the caulking part 4 of the external terminal 4, the leakage of the electrolyte solution inside the battery can 50 is prevented.

  Further, as shown in FIG. 6, one end of the bus bar B is sandwiched and fixed by a nut 1 </ b> A fastened to the screw portion 2 of the bolt 1 of the negative terminal 110 and the bus bar contact surface 15 of the external terminal 4. A conduction path X1 from the negative current collector 13 to the bus bar B is formed via the connection terminal 6 and the external terminal 4.

  Thus, the conduction path X1 can be formed without the bolt 1 made of carbon steel having low conductivity, and the bus bar B and the external terminal 4 are electrically connected by the bus bar abutting surface 15 made of a substantially flat surface. Therefore, the connection resistance between the negative electrode terminal 110 and the bus bar B can be significantly reduced. Further, by arranging concentrically the axis L1 of the screw part 2 of the bolt 1 and the axis L16 of the axis part 16 of the connection terminal 6, the conduction path X1 from the negative current collector 13 to the bus bar B can be minimized. The connection resistance between the negative electrode terminal 110 and the bus bar B can be further reduced. Further, by holding the flange portion 3 of the bolt 1 on the external terminal 4 by caulking, the bolt 1 having higher strength than the external terminal 4 and the connection terminal 6 can be easily attached to the external terminal 4.

  FIG. 7 is an exploded view of the negative electrode side of the lid assembly 32 shown in FIG. 7 shows a state before the tip end portion of the shaft portion 16 of the connection terminal 6 of the negative electrode terminal 110 is caulked.

  The negative electrode side of the lid assembly 32 includes a negative electrode terminal 110, a gasket 10, a lid 11, an insulating sheet 12, and a negative electrode current collector plate 13 as illustrated. The gasket 10 and the insulating sheet 12 are made of resin, and the gasket 10 is mainly for preventing leakage of the electrolyte in the battery can 50. The insulating sheet 12 is mainly made of the negative electrode current collector plate 13 and This is for insulating the lid 11.

  The negative electrode terminal 110 has a posture in which the bolt 1 faces the outside of the battery can 50, and the shaft portion 16 of the connection terminal 6 is a through hole provided in the gasket 10, the lid 11, the insulating sheet 12, and the negative electrode current collector plate 13. As described above, the tip portion of the shaft portion 16 is caulked to form the caulking portion 14. Thereby, the gasket 10, the lid 11, the insulating sheet 12, and the negative electrode current collector plate 13 are sandwiched and fixed between the upper end portion (receiving portion 5) and the caulking portion 14 of the external terminal 4.

  8 shows the negative electrode terminal 110 shown in FIG. 7, FIG. 9 is a longitudinal sectional view of the negative electrode terminal 110 shown in FIG. 8, and FIG. 10 is an exploded view of the negative electrode terminal 110 shown in FIG. It is shown.

  As shown in FIGS. 8 and 9, the negative electrode terminal 110 includes an external terminal 4, a connection terminal 6, and a bolt 1. Here, the external terminal 4 and the connection terminal 6 are integrally formed. The bolt 1 has a truncated pyramid-shaped flange portion 3 having an inclined surface 9 that tapers toward the outside of the battery can 50 at the base end portion, and the external terminal 4 is at the upper end portion. In order to receive the flange portion 3 of the bolt 1, the receiving portion 5 is provided with a recess 7 having a shape complementary to at least the bottom surface and the side surface of the flange portion 3.

  Accordingly, as shown in FIG. 10, after the flange portion 3 of the bolt 1 is inserted into the recess portion 7 provided in the receiving portion 5 of the external terminal 4, the periphery of the recess portion 7 of the external terminal 4 is inclined to the flange portion 3. Caulking portion 8 is formed on the inclined surface 9 by being caulked to the surface 9 side, and the flange portion 3 of the bolt 1 is clamped and fixed to the external terminal 4. At that time, the vicinity of the inclined surface 9 of the receiving portion 5 of the external terminal 4 is plastically deformed, but the bus bar contact surface 15 is not plastically deformed and is maintained flat.

  With such a configuration, the contact area between the negative electrode terminal 110 and the bus bar can be increased, and the connection resistance between the bus bar and the connection terminal 6 can be reduced as compared with the prior art. Further, by using the high-strength bolt 1 by fixing the bolt 1 and the external terminal 4 by caulking, welding between different metals of the bolt 1 and the external terminal 4, specifically, welding of copper or copper alloy and carbon steel is performed. Thus, the bolt 1 can be easily attached to the external terminal 4 and the assemblability of the secondary battery 500 can be improved as compared with the prior art.

  Further, by arranging the axial center L1 of the screw portion 2 of the bolt 1 and the axial center L16 of the shaft portion 16 of the connection terminal 6 close to each other, more preferably concentrically, the negative current collector 13 to the bus bar B. The direction of the conduction path X1 can be shortened, and the connection resistance between the negative electrode terminal 110 and the bus bar B can be further reduced.

  When the bolt 1 and the external terminal 4 are caulked and fixed, the holding force of the bolt 1 and the external terminal 4 is remarkably increased by forming the caulking portion 8 over the entire circumference of the flange portion 3 of the bolt 1. Can do. Further, as shown in the drawing, both the bottom surface of the flange portion 3 of the bolt 1 and the bottom surface of the concave portion 7 of the receiving portion 5 of the external terminal 4 are formed into a polygonal shape in plan view, thereby tightening the nut 1A to the bolt 1. The relative rotation of the bolt 1 with respect to the external terminal 4 can be effectively prevented, and the assemblability of the secondary battery 500 can be further improved.

  Next, with reference to FIGS. 11 to 16, the component configuration on the positive electrode side of the lid assembly 32 shown in FIG. 4 will be described more specifically.

  11 is an enlarged view of the positive electrode side of the lid assembly 32 shown in FIG. 4, and FIG. 12 is a BB arrow view of the positive electrode side of the lid assembly 32 shown in FIG. FIG. 12 shows a state in which the other end of the bus bar B is fastened and fixed to the bolt 20 of the positive terminal 120 with a nut 20A.

  As shown in FIGS. 11 and 12, the positive electrode terminal 120 is electrically connected to the connection terminal 23 that is electrically connected to the positive electrode of the wound body 45 via the positive electrode current collector plate 30 and the connection terminal 23. In order to fasten and fix the bus bar with the external terminal 27 having a substantially flat bus bar contact surface 28 that contacts the bus bar, and the bus bar contact surface 28 of the external terminal 27, the battery can 50 and a bolt 20 projecting outward. Here, the connection terminal 23 is disposed on the lid 11 via the gasket 10, and the bolt 20 is disposed substantially at the center of the bus bar contact surface 28 of the external terminal 27. Further, the axis L20 of the screw portion 21 of the bolt 20 and the axis L24 of the shaft portion 24 of the connection terminal 23 are arranged concentrically.

  The external terminal 27 and the connection terminal 23 are integrally formed by welding and joining at a boundary portion 29 </ b> A between the external terminal 27 and the connection terminal 23 formed on the outer peripheral surface of the external terminal 27 and the connection terminal 23. That is, a welded portion 29 that joins the external terminal 27 and the connection terminal 23 is formed on the outer peripheral surfaces of the external terminal 27 and the connection terminal 23.

  More specifically, the external terminal 27 has a cylindrical shape provided with a through hole 27B through which the threaded portion 21 of the bolt 20 penetrates at the center, and the upper end of the connection terminal 23 is bolted at the center. In order to receive the 20 flange portions 22, it has a cylindrical shape with a recess 26 having a shape complementary to at least the bottom and side surfaces of the flange portion 3. The external terminal 27 and the connection terminal 23 have substantially the same shape in plan view, and have side end surfaces 27A and 23A extending in a direction orthogonal to the bus bar contact surface 28 of the external terminal 27. doing. And the welding part 29 mentioned above is formed in the side terminal surfaces 27A and 23A of the external terminal 27 and the connection terminal 23, and the external terminal 27 and the connection terminal 23 contact the connection terminal which consists of a surface facing the bus-bar contact surface 28. It is welded and joined in a posture in contact with the surface.

  Further, the bolt 20 has a flange portion 22 having a substantially rectangular flat plate shape at a base end portion thereof, and the connection terminal 23 has a receiving portion 25 having a recess portion 26 for receiving the flange portion 22 at an upper end portion thereof. doing. Further, the external terminal 27 has a through-hole 27 </ b> B having a size larger than the outer shape of the screw portion 21 of the bolt 20 and smaller than the outer shape of the flange portion 22 of the bolt 20, above the concave portion 26 of the connection terminal 23. . Therefore, in a state where the flange portion 22 of the bolt 20 is disposed in the concave portion 26 of the receiving portion 25 of the connection terminal 23 and the screw portion 21 of the bolt 20 passes through the through hole 27B, the external terminal 27 is connected to the welding portion 29. The flange portion 22 of the bolt 20 is sandwiched between the connection terminal 23 and the external terminal 27 by welding to the connection terminal 23. In addition, the load which clamps the flange part 22 of the volt | bolt 20 can be adjusted by adjusting the penetration depth of the said welding part 29. FIG.

  The external terminal 27 and the connection terminal 23 described above are resistant to the electrolytic solution, the connection resistance is lowered, and the same kind of metal material is selected to facilitate welding. It is made of some aluminum or aluminum alloy. The bolt 20 is a carbon steel having a higher strength than aluminum or an aluminum alloy in order to increase the tightening torque of the nut 20A when the other end of the bus bar B is fastened and fixed to the bolt 20 using the nut 20A. It is composed of

  As shown in the figure, the gasket 10, the lid 11, the insulating sheet 12, and the positive electrode current collector plate 30 are formed by caulking the tip portion of the shaft portion 24 of the connection terminal 23 of the positive electrode terminal 120 to form the caulking portion 35. While being clamped and fixed by the upper end part (receiving part 25) and the caulking part 35 of the connection terminal 23, the leakage of the electrolyte solution inside the battery can 50 is prevented.

  Further, as shown in FIG. 12, the other end of the bus bar B is clamped and fixed by a nut 20A fastened to the screw portion 21 of the bolt 20 of the positive terminal 120 and the bus bar abutting surface 28 of the external terminal 27. Thus, a conduction path Y1 from the positive current collector 30 to the bus bar B is formed via the connection terminal 23 and the external terminal 27.

  In this way, the conduction path Y1 can be formed without using the bolt 20 made of carbon steel having low conductivity, and the bus bar contact surface made of a substantially flat surface having a relatively large contact area between the bus bar B and the external terminal 27. Therefore, the connection resistance between the positive terminal 120 and the bus bar B can be remarkably reduced. Further, by arranging the axis L20 of the screw portion 21 of the bolt 20 and the axis L24 of the shaft portion 24 of the connection terminal 23 concentrically, the conduction path Y1 from the positive current collector 30 to the bus bar B can be minimized. The connection resistance between the positive terminal 120 and the bus bar B can be further reduced. Further, by holding the flange portion 22 of the bolt 20 between the external terminal 27 and the connection terminal 23, the bolt 20 having a higher strength than the external terminal 27 or the connection terminal 23 can be easily attached to the external terminal 27. Can do.

  FIG. 13 is an exploded view of the positive electrode side of the lid assembly 32 shown in FIG. FIG. 13 shows a state before the tip end portion of the shaft portion 24 of the connection terminal 23 of the positive electrode terminal 120 is caulked.

  As shown in the figure, the positive electrode side of the lid assembly 32 includes a positive electrode terminal 120, a gasket 10, a lid 11, an insulating sheet 12, and a positive electrode current collector plate 30.

  The positive electrode terminal 120 is in such a posture that the bolt 20 faces the outside of the battery can 50, and the shaft portion 24 of the connection terminal 23 is a through hole provided in the gasket 10, the lid 11, the insulating sheet 12, and the negative electrode current collector plate 13. As described above, the tip end portion of the shaft portion 24 is caulked to form the caulking portion 35. Thereby, the gasket 10, the lid 11, the insulating sheet 12, and the positive electrode current collector plate 30 are sandwiched and fixed between the upper end portion (receiving portion 25) and the caulking portion 35 of the connection terminal 23.

  FIG. 14 shows the positive terminal 120 shown in FIG. 13, FIG. 15 is a longitudinal sectional view of the positive terminal 120 shown in FIG. 14, and FIG. 16 is an exploded view of the positive terminal 120 shown in FIG. It is shown.

  As shown in FIGS. 14 and 15, the positive terminal 120 includes an external terminal 27, a connection terminal 23, and a bolt 20, and the external terminal 27 and the connection terminal 23 are connected to a boundary portion 29 </ b> A between the external terminal 27 and the connection terminal 23. It welds with the welding part 29 provided in this. Further, the bolt 20 has a rectangular flat plate-like flange portion 22 at its base end portion, and the connection terminal 23 has a recess 26 for receiving the flange portion 22 of the bolt 20 at its upper end portion. Part 25. The external terminal 27 has a substantially flat bus bar abutting surface 28 on its upper surface, and is larger than the outer shape of the screw portion 21 of the bolt 20 at the center of the bus bar abutting surface 28, and the flange portion 22 of the bolt 20. A through hole 27B having a size smaller than the outer shape of the through hole 27B is provided.

  Accordingly, as shown in FIG. 16, after the flange portion 22 of the bolt 20 is inserted into the recess 26 provided in the receiving portion 25 of the connection terminal 23, the screw portion 21 of the bolt 20 is inserted into the through hole 27 </ b> B of the external terminal 27. The connecting terminal 23 and the external terminal 27 are fitted to each other, the boundary portion 29A is laser-welded, and the welded portion 29 is formed over the entire circumference of the side end surfaces 23A and 27A of the connecting terminal 23 and the external terminal 27. By forming, the flange portion 22 of the bolt 20 is sandwiched and fixed between the connection terminal 23 and the external terminal 27.

  Here, the connection terminal contact surface that contacts the connection terminal 23 of the external terminal 27 has a concave shape in which the side end portion protrudes from the center portion (see FIG. 15), and the external terminal 27 of the connection terminal 23. The external terminal contact surface that contacts the external terminal 27 has a shape complementary to the connection terminal contact surface, and the connection terminal contact surface of the external terminal 27 and the external terminal contact surface of the connection terminal 23 are fitted together. Since the external terminal 27 and the connection terminal 23 are welded and joined in this state, a relative positional shift between the external terminal 27 and the connection terminal 23 in the welding process can be effectively suppressed.

  Further, as described above, the welded portion 29 is provided on the side end surfaces 23 </ b> A and 27 </ b> A of the outer peripheral surfaces of the connection terminal 23 and the external terminal 27 that are orthogonal to the bus bar contact surface 28 of the external terminal 27. Thereby, although spatter is generated during laser welding, it is possible to prevent the spatter from adhering to the bus bar contact surface 28 of the external terminal 27 and increase the contact resistance between the bus bar and the bus bar contact surface 28. Can be effectively suppressed. Furthermore, since it is possible to prevent spatter from adhering to the shaft portion 24 of the connection terminal 23, it is possible to effectively suppress the above-described caulking failure of the positive electrode terminal 120 with respect to the lid 11 and the like.

  Although the welded portion 29 can be partially formed on the outer peripheral surfaces of the connection terminal 23 and the external terminal 27, as shown in the drawing, the entire circumference of the side end surfaces 23A and 27A of the connection terminal 23 and the external terminal 27 is shown. By forming the welded portion 29 over the connecting terminal 23, the connecting terminal 23 and the external terminal 27 can be uniformly joined, and the connecting resistance between the connecting terminal 23 and the external terminal 27 can be reduced.

  With such a configuration, the contact area of the positive electrode terminal 120 with the bus bar can be increased, and the connection terminal 23 to the bus bar abutting surface 28 are configured by an integral member that is metal-bonded by welding. As compared with the prior art, the connection resistance between the bus bar and the connection terminal 23 can be reduced. Further, by holding and holding the flange portion 22 of the bolt 20 between the connection terminal 23 and the external terminal 27, for example, welding of different metals of the bolt 20 and the external terminal 27 is performed while using the relatively high-strength bolt 20. Specifically, there is no need to weld aluminum or an aluminum alloy and carbon steel, and the bolt 20 can be easily attached to the external terminal 27, and the assemblability of the secondary battery 500 is improved as compared with the prior art. be able to.

  When welding the connection terminal 23 and the external terminal 27, the holding force of the flange portion 22 of the bolt 20 by the connection terminal 23 and the external terminal 27 is adjusted by adjusting the penetration depth of the welded portion 29. Can do. Further, as shown in the drawing, both the bottom surface of the flange portion 22 of the bolt 20 and the bottom surface of the concave portion 26 of the receiving portion 25 of the connection terminal 23 are formed into a polygonal shape in plan view, thereby tightening the nut 20A to the bolt 20. The relative rotation of the bolt 20 with respect to the connection terminal 23 can be effectively prevented, and the assemblability of the secondary battery 500 can be further improved.

  In the secondary battery 500 of the first embodiment, the connection terminal 6 and the external terminal 4 are integrally formed on the negative electrode side, the bolt 1 is held by caulking a part of the external terminal 4, and the connection terminal on the positive electrode side. 23 and the external terminal 27 are integrally formed by welding, and the bolt 20 is sandwiched and held between the connection terminal 23 and the external terminal 27, but the connection terminal 6 and the external terminal 4 are integrally formed by welding on the negative electrode side. Alternatively, the connection terminal 23 and the external terminal 27 may be integrally formed on the positive electrode side. However, the aluminum or aluminum alloy used for the positive-side connection terminal 23 and the external terminal 27 is generally lower in strength than the copper or copper alloy used for the negative-side connection terminal 6 and the external terminal 4, and the above-described external Since it is difficult to firmly hold the flange portion of the bolt by caulking the terminal, at least on the positive electrode side using aluminum or an aluminum alloy, the connection terminal 23 and the external terminal 27 are integrally formed by welding, A form in which the flange portion 22 of the bolt 20 is sandwiched between the external terminals 27 is preferable.

[Second Embodiment]
Next, a second embodiment of the secondary battery according to the present invention will be described in detail with reference to FIGS.

  The secondary battery 600 of the second embodiment is different from the secondary battery 500 of the first embodiment in that the outer shape of the external terminal of the electrode terminal is changed to a cylindrical plate shape (difference 1), In both the positive and negative electrode terminals, the external terminal and the connection terminal are separated, and the external terminal and the connection terminal are joined together by welding (difference 2), and connected to the axis of the screw thread of the bolt The difference is that the axis of the shaft portion of the terminal is eccentric (difference 3), and the other configuration is the same as that of the secondary battery 500 of the first embodiment. Accordingly, only the differences 1 to 3 will be described in detail below, and detailed description of the same configuration as the secondary battery 500 of the first embodiment will be omitted.

  FIG. 17 shows an appearance of the second embodiment of the secondary battery according to the present invention.

  The illustrated secondary battery 600 is generally configured by a rectangular box-shaped battery can 76 having an opening at one end and a power storage element assembly 200 accommodated in the battery can 76. Here, the power storage element assembly 200 has a rectangular flat cover 66, and the opening of the battery can 76 is welded and sealed to the cover 66 of the power storage element assembly 200. Further, the lid 66 is provided with a liquid injection hole (not shown) for injecting the electrolyte into the battery can 76, and after the electrolyte is injected into the battery can 76 through the liquid injection hole. The liquid injection plug 70 is inserted into the liquid injection hole and sealed by laser welding so that the electrolyte does not leak to the outside.

  Here, as described in the difference 1, the outer shape of the external terminal 60 of the negative electrode terminal 210 and the external terminal 80 of the positive electrode terminal 220 arranged on the lid 66 are substantially rectangular flat plates, The outer shapes of the bus bar contact surfaces 63 and 83 of the terminals 60 and 80 are substantially rectangular in plan view. More specifically, the bus bar contact surfaces 63 and 83 of the external terminals 60 and 80 have a rectangular shape having a long side in a direction along the longitudinal direction of the rectangular flat cover 66 in a plan view. Thereby, for example, the contact area between the external terminals 60 and 80 and the bus bar, in particular, the lid of the battery can 76, as compared with the case where the outer shape of the bus bar contact surface is substantially circular in a plan view as in the first embodiment, for example. The contact area with the bus bar in the longitudinal direction of 66 can be increased, and the connection resistance between the negative electrode terminal 210 and the positive electrode terminal 220 and the bus bar can be significantly reduced. In addition, the bus bar contact surfaces 63 and 83 of the external terminals 60 and 80 may have a polygonal shape having a contact area larger than that of at least a substantially circular shape instead of the rectangular shape in a plan view.

  The negative electrode terminal 210 and the positive electrode terminal 220 are disposed on the lid 66 of the battery can 76 via resin resin terminal blocks 64 and 84, respectively. The negative electrode terminal 210, the positive electrode terminal 220, and the lid 66 are insulated. ing. Further, the bolts 61 and 81 of the negative electrode terminal 210 and the positive electrode terminal 220 are arranged so as to protrude toward the outside of the battery can 76 from the substantially central portions of the bus bar contact surfaces 63 and 83 of the external terminals 60 and 80, respectively. Yes.

  As described in the second difference, in the secondary battery 600 of the second embodiment, the external terminal and the connection terminal are separated from each other in both the positive and negative electrode terminals, and the external terminal and the connection terminal are joined by welding. Are integrated. That is, the positive electrode terminal and the negative electrode terminal have substantially the same configuration although the forming materials are different. Therefore, below, the negative electrode side of the secondary battery 600 will be specifically described, and detailed description of the positive electrode side will be omitted.

  18 is an enlarged view of the negative electrode side of the lid assembly 72 of the secondary battery 600 shown in FIG. 17, and FIG. 19 is a CC arrow on the negative electrode side of the lid assembly 72 shown in FIG. FIG. FIG. 19 shows a state where one end of the bus bar B is fastened and fixed to the bolt 61 of the negative electrode terminal 210 with a nut 61A.

  As shown in FIG. 18 and FIG. 19, the negative electrode terminal 210 is electrically connected to the connection terminal 62, which is electrically connected to the negative electrode of the wound body via the negative electrode current collector plate 68, In order to fasten and fix the bus bar with the external terminal 60 having a substantially rectangular and substantially planar bus bar contact surface 63 in contact with the bus bar and the bus bar contact surface 63 of the external terminal 60, the bus bar contact And a bolt 61 projecting from the surface 63 toward the outside of the battery can 76. Here, the connection terminal 62 is disposed on the lid 66 via the terminal block 64, and the bolt 61 is disposed substantially at the center of the bus bar abutting surface 63 of the external terminal 60.

  The external terminal 60 and the connection terminal 62 are integrally formed by welding at a boundary portion 69 </ b> A between the external terminal 60 and the connection terminal 62 formed on the outer peripheral surface of the external terminal 60 and the connection terminal 62. That is, a welded portion 69 for joining the external terminal 60 and the connection terminal 62 is formed on the outer peripheral surfaces of the external terminal 60 and the connection terminal 62.

  More specifically, the external terminal 60 has a substantially rectangular flat plate shape with a through hole 60 </ b> B through which the threaded portion 71 of the bolt 61 penetrates at the center, and the upper end of the connection terminal 62 is at the center. It has a substantially rectangular flat plate shape having a recess 78 for receiving the flange portion 73 of the bolt 61. The external terminal 60 and the connection terminal 62 have substantially the same shape in plan view, and have side end surfaces 60A and 62A extending in a direction orthogonal to the bus bar contact surface 63 of the external terminal 60. doing. Then, the welded portion 69 described above is formed on the side end surfaces 60A and 62A of the external terminal 60 and the connection terminal 62, and the external terminal 60 and the connection terminal 62 are contact terminal contacts made of a surface facing the bus bar contact surface 63. It is welded and joined in a posture that is in contact with the contact surface.

  The bolt 61 has a substantially rectangular flat plate-like flange portion 73 at the base end portion, and the connection terminal 62 is complementary to at least the bottom surface and the side surface of the flange portion 73 to receive the flange portion 73 at the upper end portion. It has the receiving part 77 provided with the recessed part 78 which exhibits a typical shape. Further, the external terminal 60 has a through-hole 60 </ b> B having a dimension larger than the outer shape of the screw portion 71 of the bolt 61 and smaller than the outer shape of the flange portion 73 of the bolt 61, above the recess 78 of the connection terminal 62. . Therefore, in a state where the flange portion 73 of the bolt 61 is inserted into the concave portion 78 of the receiving portion 77 of the connection terminal 62 and the screw portion 71 of the bolt 61 passes through the through hole 60B, the external terminal 60 is connected to the welding portion 69. By joining with the connection terminal 62, the flange portion 73 of the bolt 61 is sandwiched between the connection terminal 62 and the external terminal 60.

  The external terminal 60 and the connection terminal 62 are made of copper or copper alloy, which is the same metal as the negative electrode foil, and the bolt 61 is made of carbon steel having a higher strength than copper or copper alloy. .

  Also, the terminal block 64, the gasket 65, the lid 66, the insulating sheet 67, and the negative electrode current collector plate 68 are connected by caulking the tip end portion of the shaft portion 74 of the connection terminal 62 of the negative electrode terminal 210. While being clamped and fixed by the upper end part (receiving part 77) and the crimping part 75 of the terminal 62, the electrolyte solution inside the battery can 76 is prevented from leaking.

  Here, nickel is superior to copper in corrosion resistance. For example, when the secondary battery 600 is left in a corrosive environment, at least the external terminal 60 of the external terminal 60 is reduced in order to reduce the contact resistance between the negative electrode terminal 210 and the bus bar. The bus bar contact surface 63 is preferably coated with nickel plating.

  If the external terminal 60 and the connection terminal 62 are integrally formed, nickel plating may be peeled off in the caulking process of the shaft portion 74 of the connection terminal 62 described above, and the external terminal 60 and the integrally formed external terminal 60 are connected. It is difficult to coat the terminal 62 uniformly with nickel plating.

  On the other hand, in the secondary battery 600 of the second embodiment, the external terminal 60 and the connection terminal 62 are separated, and the external terminal 60 and the connection terminal 62 are joined together by welding so as to be integrated with each other. Only the external terminal 60 having the contact surface 63 can be uniformly coated with nickel plating, and the contact resistance between the negative electrode terminal 210 and the bus bar B can be reduced by making the material of the bus bar contact surface 63 nickel excellent in corrosion resistance. it can.

  Note that the same effect can be obtained even when the bus bar contact surface 63 of the external terminal 60 is coated with tin plating instead of the nickel plating described above. The reasons for selecting nickel and tin include not only having excellent corrosion resistance but also having no adverse effects such as cracking on the welded portion 69 of the external terminal 60 and the connection terminal 62.

  Then, as shown in FIG. 19, one end of the bus bar B is sandwiched and fixed by a nut 61 </ b> A fastened to the screw part 71 of the bolt 61 of the negative terminal 210 and the bus bar contact surface 63 of the external terminal 60. A conduction path X2 from the negative current collector 68 to the bus bar B is formed via the connection terminal 62 and the external terminal 60. At this time, as described above, the bus bar abutting surface 63 has a substantially rectangular shape having a long side in the direction along the longitudinal direction of the lid 66 in a plan view, for example, compared with a case where the bus bar abutting surface is circular. Since the contact area between the external terminal 60 and the bus bar B can be increased, the contact resistance with the bus bar B can be effectively reduced.

  Furthermore, in the secondary battery 600 of the second embodiment, as described in the difference 3, the shaft center L61 of the screw portion 71 of the bolt 61 and the shaft center L74 of the shaft portion 74 of the connection terminal 62 are arranged eccentrically. (Offset). More specifically, the shaft center L61 of the threaded portion 71 of the bolt 61 is disposed on the outer side in the winding axis direction of the wound body 45 with respect to the shaft center L74 of the shaft portion 74 of the connection terminal 62.

  For example, when the shaft center L61 of the bolt 61 and the shaft center L74 of the shaft portion 74 of the connection terminal 62 are arranged concentrically as in the secondary battery 500 of the first embodiment, the busbar is in contact with the busbar contact surface 63. After fixing B, when fastening the nut 61B to the bolt 61 to fix the bus bar B, if the tightening torque of the nut 61B becomes excessive, the connection terminal 62 rotates relative to the lid 66, and the negative current collector The plate 68 may also rotate in the battery can 76.

  Therefore, as described above, when the bus bar B is tightened and fixed using the nut 61B by eccentrically arranging the shaft center L61 of the screw portion 71 of the bolt 61 and the shaft center L74 of the shaft portion 74 of the connection terminal 62, Even when excessive tightening torque is applied, the relative rotation of the connection terminal 62 with respect to the lid 66 can be suppressed, and the rotation of the negative electrode current collector plate 68 within the battery can 76 is effectively suppressed. can do.

  In addition, the same effect as a negative electrode terminal can be acquired also about the external terminal of a positive electrode terminal by coating with nickel plating. That is, the external terminal 80 of the positive electrode terminal is made of aluminum, and aluminum has a thick oxide film on the surface, and the oxide of aluminum becomes an insulator. Therefore, by coating with nickel plating, the positive electrode terminal and the bus bar Contact resistance can be effectively reduced. Even in this case, if nickel plating is applied to the shaft portion (the portion to be caulked) of the connection terminal, nickel plating may be peeled off in the caulking process. Cover with plating. Moreover, it can replace with nickel plating, and the same effect can be acquired even if it coats with other plating, such as tin plating.

  FIG. 20 is an exploded view of the negative electrode side of the lid assembly 72 shown in FIG. 20 shows a state before the tip end portion of the shaft portion 74 of the connection terminal 62 of the negative electrode terminal 210 is caulked.

  The negative electrode side of the lid assembly 72 includes a negative electrode terminal 210, a terminal block 64, a gasket 65, a lid 66, an insulating sheet 67 and a negative electrode current collector plate 68 as shown in the figure. The terminal block 64, the gasket 65, and the insulating sheet 67 are made of resin, and the negative electrode terminal 210 and the lid 66 are insulated from the negative electrode current collector plate 68 and the lid 66, respectively.

  The negative electrode terminal 210 is arranged such that the bolt 61 faces the outside of the battery can 76, and the shaft portion 74 of the connection terminal 62 is provided on the terminal block 64, the gasket 65, the lid 66, the insulating sheet 67 and the negative electrode current collector plate 68. As described above, the tip end portion of the shaft portion 74 is caulked to form the caulking portion 75. Thereby, the terminal block 64, the gasket 65, the lid 66, the insulating sheet 67, and the negative electrode current collector plate 68 are sandwiched and fixed by the upper end portion (receiving portion 77) and the caulking portion 75 of the connection terminal 60.

  FIG. 21 is an exploded view of the negative electrode terminal 210 shown in FIG.

  The negative terminal 210 includes an external terminal 60, a connection terminal 62, and a bolt 61. Further, the bolt 61 has a flange portion 73 having a substantially rectangular flat plate shape at the base end portion, and the connection terminal 62 has a concave portion 78 for receiving the flange portion 73 of the bolt 61 at the upper end portion thereof. A receiving portion 77 is provided. Further, the external terminal 60 has a bus bar abutting surface 63 having a substantially flat surface coated with nickel plating on the upper surface thereof, and is larger than the outer shape of the threaded portion 71 of the bolt 61 at the center of the bus bar abutting surface 63, The through hole 60 </ b> B is smaller than the outer shape of the flange portion 73 of the bolt 61.

  Thus, after the flange portion 73 of the bolt 61 is inserted into the recess 78 provided in the receiving portion 77 of the connection terminal 62, the screw portion 71 of the bolt 61 is inserted into the through hole 60 </ b> B of the external terminal 60. The flange portion of the bolt 61 is formed by fitting the terminal 62 and the external terminal 60 and laser welding the boundary portion 69 </ b> A to form the welded portion 69 over the entire outer periphery of the connection terminal 62 and the external terminal 60. 73 is clamped and fixed between the connection terminal 62 and the external terminal 60.

  With such a configuration, the contact area between the negative electrode terminal 210 and the bus bar can be significantly increased, and the connection resistance between the bus bar and the connection terminal 62 can be further reduced as compared with the prior art.

  Further, by coating the bus bar contact surface 63 of the external terminal 60 with nickel plating or tin plating, corrosion resistance of the bus bar contact surface 63 of the external terminal 60 can be suppressed, and the contact between the external terminal 60 and the bus bar can be suppressed. An increase in resistance can be effectively suppressed.

  Furthermore, the negative electrode current collector plate in the battery can 76 when the nut 61A is fastened to the bolt 61 is arranged by eccentrically arranging the axial center L61 of the bolt 61 of the negative electrode terminal 210 and the axial center L74 of the shaft portion 74 of the connection terminal 62. The rotation of 68 can be suppressed, and the assemblability of the secondary battery 600 can be further improved.

  The present invention is not limited to the first and second embodiments described above, and includes various modifications. For example, the first and second embodiments described above have been described in detail for easy understanding of the present invention, and are not necessarily limited to those 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. Moreover, it is possible to add / delete / replace other configurations for a part of the configurations of the first and second embodiments.

1: bolt, 2: screw part, 3: flange part, 4: negative electrode external terminal, 5: receiving part, 6: negative electrode connection terminal, 7: recessed part, 8: caulking part, 9: inclined surface, 10: gasket, 11 : Lid, 12: Insulating sheet, 13: Negative current collector plate, 14: Caulking part, 15: Bus bar contact surface, 16: Shaft part, 20: Bolt, 21: Screw part, 22: Flange part, 23: Positive electrode connection Terminal: 24: Shaft part, 25: Receiving part, 26: Recessed part, 27: Positive electrode external terminal, 28: Bus bar contact surface, 29: Welded part, 30: Positive electrode current collector plate, 31: Injection hole, 32: Lid Assembly: 33: Negative electrode side ultrasonic bonding part, 34: Positive electrode side ultrasonic bonding part, 35: Caulking part, 40: Positive electrode foil, 41: Positive electrode active material mixture layer, 42: Separator, 43: Negative electrode foil, 44 : Negative electrode active material mixture layer, 45: Winding body, 50: Battery can, 51: Injection stopper, 60: Negative electrode external terminal 61: bolt, 62: negative electrode connection terminal, 63: bus bar contact surface, 64: terminal block, 65: gasket, 66: lid, 67: insulating sheet, 68: negative electrode current collector plate, 69: welded part, 70: Injection stopper, 71: screw part, 72: lid assembly, 73: flange part, 74: shaft part, 75: caulking part, 76: battery can, 77: receiving part, 78: recessed part, 80: positive electrode external terminal, 81: bolt, 83: bus bar contact surface, 84: terminal block, 100, 200: power storage element assembly, 110, 210: negative electrode terminal, 120, 220: positive electrode terminal, 500, 600: secondary battery, B: bus bar

Claims (12)

A connection terminal connected to the electrode of the electricity storage element via a current collector plate;
An external terminal that is electrically connected to the connection terminal and has a bus bar abutting surface that abuts against the bus bar;
A bolt projecting from the bus bar contact surface toward the outside of the battery can in order to fasten and fix the bus bar at the bus bar contact surface of the external terminal,
The external terminal holds the bolt made of a metal having a higher strength than the external terminal and the connection terminal,
Each of the external terminal and the connection terminal has the same shape in plan view, and has a side end surface extending in a direction orthogonal to the bus bar contact surface of the external terminal,
The external terminal has a connection terminal contact surface that contacts the connection terminal on a surface facing the bus bar contact surface,
The external terminal and the connection terminal are welded together at a boundary portion between the external terminal and the connection terminal on the side end surface in a posture in which the external terminal and the connection terminal are in contact with each other at the connection terminal contact surface. Secondary battery.   The secondary battery according to claim 1, wherein the external terminal and the connection terminal are made of the same metal.   The secondary battery according to claim 1, wherein the external terminal and the connection terminal are welded together around the entire circumference of the side end surface. The bolt has a flange portion at its proximal end,
The connection terminal has a receiving portion having a recess having a shape complementary to at least a bottom surface and a side surface of the flange portion in order to receive the flange portion at an upper end portion thereof,
The external terminal is, above the recess of the connecting terminals is smaller than the outer diameter of the flange portion has a through hole formed of not the magnitude dimension than the outer shape of the screw portion of the bolt,
The external terminal and the connection terminal are welded and joined in a posture in which the flange portion is disposed in the concave portion and the screw portion penetrates the through hole,
The secondary battery according to any one of claims 1 to 3, wherein the flange portion of the bolt is held by the external terminal and the connection terminal.   5. The secondary battery according to claim 4, wherein the bottom surface of the flange portion and the bottom surface of the recess have a polygonal shape in plan view. The connection terminal contact surface that contacts the connection terminal of the external terminal has a concave shape whose side end portion protrudes from the center portion,
The external terminal contact surface that contacts the external terminal of the connection terminal has a shape complementary to the connection terminal contact surface,
2. The connection terminal contact surface of the external terminal and the external terminal contact surface of the connection terminal are fitted, and the external terminal and the connection terminal are welded and joined. The secondary battery as described in any one of 1-5.   The secondary battery according to claim 1, wherein the external terminal is coated with nickel plating or tin plating.   The secondary battery according to claim 1, wherein the bus bar contact surface of the external terminal has a circular shape in plan view.   The secondary battery according to any one of claims 1 to 7, wherein the bus bar contact surface of the external terminal has a polygonal shape in a plan view. The secondary battery includes a rectangular flat lid that seals a battery can in which a power storage element is accommodated,
The secondary battery according to claim 9, wherein the bus bar contact surface of the external terminal has a rectangular shape having a long side in a direction along a longitudinal direction of the lid in a plan view.   11. The secondary battery according to claim 1, wherein an axis of a screw part of the bolt and an axis of an axis of the connection terminal are arranged concentrically.   11. The secondary battery according to claim 1, wherein an axis of a screw portion of the bolt and an axis of a shaft portion of the connection terminal are arranged eccentrically.

Images