JP2016192322A - Secondary battery, and battery pack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influence of performing welding treatment in a secondary battery.SOLUTION: A negative collector 18 for electrically connecting a negative electrode to a negative electrode terminal, and an external conductive member 44 made of aluminium based metal and welded and connected to the negative terminal 40 are provided on the side of the negative electrode terminal 40 of a secondary battery 10. The negative electrode terminal 40 includes a flange part 80 disposed on the outer surface side of a sealing plate 20, and an annular insertion part 82 which is connected to one side of the flange part 80 and the tip side of which is connected to the negative electrode collector 18. The negative electrode terminal 40 has a first region 90 made of copper based metal and a second region 92 made of aluminum based metal, the annular insertion part 82 is formed by the first region 90, a boundary part between the first region 90 and the second region 92 is provided in the flange part 80, and the external conductive member 44 is welded to the second region 92.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a secondary battery and an assembled battery in which a plurality of secondary batteries are connected.

  Patent Document 1 states that in a rectangular lithium ion secondary battery, an aluminum-based metal is used as a positive electrode core, and a copper-based metal is generally used as a negative electrode core. In addition, it states that the same aluminum-based metal as the positive electrode is used for the positive electrode external electrode material welded to the positive electrode side, and the same copper-based metal as the negative electrode is used for the negative electrode external electrode material welded to the negative electrode side. Yes.

JP 2013-157130 A

  An object of this invention is to provide the secondary battery and assembled battery which can reduce the influence by performing welding.

  A secondary battery according to the present invention includes an electrode body having a positive electrode and a negative electrode, an exterior body having an opening, housing the electrode body, a sealing plate for sealing the opening of the exterior body, and attached to the sealing plate A positive electrode terminal electrically connected to the positive electrode, and a negative electrode terminal inserted into a negative electrode terminal mounting hole provided in the sealing plate via a negative electrode side insulating member and electrically connected to the negative electrode. On the terminal side, a negative electrode current collector that is electrically connected between the negative electrode and the negative electrode terminal, and an external conductive member that is connected to the negative electrode terminal and made of an aluminum-based metal are provided. Has a current collector through-hole into which the negative electrode terminal is inserted, the negative electrode terminal has a wider outer area than the opening area of the negative electrode terminal mounting hole, and is disposed on the outer surface side of the sealing plate, and Insertion part connected to one surface of flange part, negative electrode terminal mounting hole and current collector through Including a first region composed of a copper-based metal and a second region composed of an aluminum-based metal, and the insertion unit is a first region. It is comprised by the area | region, the boundary part between 1st area | region and 2nd area | region is provided in a flange part, and an external conductive member is connected to 2nd area | region.

  An assembled battery according to the present invention is an assembled battery configured by connecting a plurality of the secondary batteries, and an external conductive material having one end connected to a negative electrode terminal of one secondary battery in an adjacent secondary battery. The other end of the member is connected to the positive terminal of the secondary battery on the other side.

  The secondary battery and the assembled battery according to the present invention can reduce the influence caused by welding.

1 is a perspective view of a secondary battery according to an embodiment of the present invention. It is a top view about the positive electrode terminal side of FIG. It is sectional drawing along the AA line of FIG. FIG. 3A is a diagram showing a state before the welding process, and FIG. 3B is a diagram showing a state after the welding process. It is a top view about the negative electrode terminal side of FIG. It is sectional drawing along the BB line of FIG. FIG. 5A is a diagram showing a state before the welding process, and FIG. 5B is a diagram showing a state after the welding process. It is the figure which extracted the part of the negative electrode terminal about Fig.5 (a). It is a figure which shows some modifications about a negative electrode terminal. It is a figure which shows the connection state of two adjacent secondary batteries about the assembled battery of embodiment which concerns on this invention.

  Embodiments of the present invention will be described below in detail with reference to the drawings. The materials, dimensions, shapes, and the like described below are examples for explanation, and can be appropriately changed according to the specifications of the secondary battery. In the following, corresponding elements in all drawings are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is an external perspective view of the secondary battery 10. The secondary battery 10 is a prismatic lithium ion battery having a bottomed cylindrical rectangular parallelepiped casing 12. Inside the secondary battery 10, an electrode body 14 in which a positive electrode and a negative electrode are laminated and wound through a separator and formed into a flat shape is accommodated including a non-aqueous electrolyte. FIG. 1 shows three XYZ directions orthogonal to each other. The Z direction is the axial direction of the exterior body 12, and the + Z direction is the opening side of the exterior body 12. The Y-axis direction is the lateral direction of the exterior body 12, the positive electrode terminal side is the + Y direction, and the negative electrode terminal side is the -Y direction. The X direction is the thickness direction of the exterior body 12.

  The exterior body 12 is a rectangular bottomed cylindrical shape having a bottom part, and is a rectangular parallelepiped container having an opening in the + Z direction which is an upper part. As the exterior body 12, a metal material formed into a predetermined shape is used. As the metal material used for the exterior body 12, an aluminum-based metal (aluminum, an aluminum alloy mainly composed of aluminum) or an iron-based metal (iron, an iron alloy mainly composed of iron) is preferable.

  An electrode body 14 indicated by a broken line in FIG. 1 is formed by laminating and winding a positive electrode and a negative electrode through a separator, and is formed into a flat shape. The negative electrode current collector 18 is connected to the end portion in the -Y direction.

  The positive electrode has a positive electrode active material layer formed on both surfaces of a metal foil as a positive electrode core. As the positive electrode core, an aluminum metal foil is preferably used. The aluminum-based metal is aluminum or an aluminum alloy mainly composed of aluminum. The positive electrode active material contains a lithium transition metal oxide capable of inserting and extracting lithium ions. The negative electrode has a negative electrode active material layer formed on both surfaces of a metal foil as a negative electrode core. It is preferable to use a copper-based metal foil as the negative electrode core. The copper-based metal is copper or a copper alloy mainly composed of copper. The negative electrode active material is a carbonaceous material. The separator is made of an ion permeable material.

The non-aqueous electrolyte uses ethylene carbonate (EC), ethyl methyl carbonate (EMC), dimethyl carbonate (DMC), etc. as a non-aqueous solvent, to which lithium hexafluorophosphate (LiPF ₆ ) is added as an electrolyte salt. It is.

  The above compositional materials are illustrative examples, and other compositional materials can be used depending on the specifications of the lithium ion secondary battery.

  The electrode body 14 is formed by laminating a positive electrode, a separator, and a negative electrode, and winding and flattening. The positive electrode current collector 16 is a conductive lead terminal material connected to the positive electrode core body exposed at the + Y direction end of the electrode body 14. As the positive electrode current collector 16, an aluminum metal plate processed is used. Welding is used as a connection means between the positive electrode current collector 16 and the positive electrode core. The negative electrode current collector 18 is a conductive lead terminal material connected to the negative electrode core body exposed at the −Y direction end of the electrode body 14. As the negative electrode current collector 18, a copper-based metal plate processed is used. Welding is used as a connection means between the negative electrode current collector 18 and the negative electrode core.

  The sealing plate 20 is a lid plate that closes the opening of the exterior body 12. The sealing plate 20 and the exterior body 12 are integrated by welding, and the electrode body 14, the positive electrode current collector 16, the negative electrode current collector 18 and the like are accommodated in the internal space. The sealing plate 20 includes a gas discharge valve 22 that opens the internal pressure when the pressure in the internal space formed by the exterior body 12 and the sealing plate 20 exceeds a threshold pressure, and an internal space in which the electrode body 14 and the like are stored. A liquid injection hole for injecting a non-aqueous electrolyte and its sealing plug 24 are provided. As the sealing plate 20, an aluminum plate processed into a predetermined shape is used. As an integration means of the sealing plate 20 and the exterior body 12, welding is used.

  The positive electrode terminal 30 provided on the end portion side in the + Y direction of the sealing plate 20 is a positive electrode terminal in the secondary battery 10. The positive electrode terminal 30 is electrically insulated from the sealing plate 20 through a positive electrode-side insulating member 32 made of resin. The positive electrode terminal 30 is inserted into a positive electrode terminal mounting hole provided in the sealing plate 20 and is electrically connected to the positive electrode current collector 16. An external conductive member 34 is connected to the positive electrode terminal 30 on the battery outer side. A bolt 36 is connected to a position shifted from the position where the positive electrode terminal 30 is connected in the external conductive member 34. Details of the connection between the positive electrode terminal 30 and the positive electrode current collector 16 will be described later.

  The negative electrode terminal 40 provided on the end side in the −Y direction of the sealing plate 20 is a negative electrode terminal in the secondary battery 10. The negative electrode terminal 40 is electrically insulated from the sealing plate 20 via a resin negative electrode side insulating member 42. The negative electrode terminal 40 is inserted into a negative electrode terminal mounting hole provided in the sealing plate 20 and is electrically connected to the negative electrode current collector 18. An external conductive member 44 is connected to the negative electrode terminal 40 on the battery outer side. A bolt 46 is connected to a position shifted from the position where the negative electrode terminal 40 is connected in the external conductive member 44. Details of the connection between the negative electrode terminal 40 and the negative electrode current collector 18 will be described later.

  Next, the contents of attaching the positive electrode terminal 30 and the negative electrode terminal 40 to the sealing plate 20 will be described in detail with reference to FIGS.

  First, the connection structure on the positive electrode terminal 30 side will be described with reference to FIGS. 2 and 3, and the connection structure on the negative electrode terminal 40 side will be described with reference to FIGS. 4 to 7.

  FIG. 2 is a diagram in which the periphery of the positive electrode terminal 30 is extracted from the top view of the secondary battery 10. In FIG. 2, the directions of the X-axis and the Y-axis are reversed from those in FIG. FIG. 2 shows a sealing plate 20, a positive terminal 30, a positive-side insulating member 32, a positive-side external conductive member 34, and a positive-side bolt 36. 3 is a cross-sectional view taken along line AA in FIG. 3A shows a state before the welding process of the positive electrode terminal 30 and the external conductive member 34, and FIG. 3B shows a state after the welding process.

  In FIG. 3A, the positive terminal mounting hole 50 provided in the sealing plate 20 is a hole into which the positive terminal 30 is inserted. In the sealing plate 20, a recess 21 is provided along the outer peripheral side of the positive electrode terminal mounting hole 50. A part of the insulating member 32 is disposed in the recess 21. The recess 21 is not an essential configuration. Further, the insulating member 32 is not necessarily arranged in the recess 21.

  The current collector through hole 52 provided in the positive electrode current collector 16 is a hole into which the positive electrode terminal 30 is inserted. The positive electrode terminal mounting hole 50 and the current collector through-hole 52 are aligned with each other at the center axes of the two holes during assembly.

  The positive electrode terminal 30 includes a flange portion 60 and an annular insertion portion 62 connected to one surface which is the −Z side surface of the flange portion 60. The flange portion 60 has a larger outer area than the opening area of the positive electrode terminal mounting hole 50, and is a bowl-shaped portion arranged on the outer surface side of the sealing plate 20 in the positive electrode terminal 30. The outer diameter of the flange portion 60 is smaller than the inner diameter of the recess 21 provided in the sealing plate 20. The annular insertion portion 62 is a portion that is inserted into the positive terminal mounting hole 50 and the current collector through hole 52 in the positive terminal 30. In addition, the boundary between the flange part 60 and the cyclic | annular insertion part 62 was shown with the dashed-dotted line. The same applies to the following drawings.

  The protrusion 64 provided on the other surface which is the + Z side surface of the flange portion 60 is a welding end when welding the positive electrode terminal 30 and the external conductive member 34 on the positive electrode side. The protrusion 64 is continuously provided in an annular shape. Instead of this, a plurality of projections 64 arranged in an annular shape may be provided. Or it can also be set as the column shape which does not have a recessed part in an upper surface.

  The distal end portion 66 of the insertion portion 62 is expanded on the positive electrode current collector 16 and crimped on the positive electrode current collector 16. As a result, the positive electrode terminal 30 and the positive electrode current collector 16 are fixedly connected to the sealing plate 20. In addition, it is preferable that the crimped tip 66 and the positive electrode current collector 16 are further connected by welding. Moreover, the insertion part 62 does not necessarily need to be annular, and may be a columnar shape having no recess.

  The current collector 54 is an insulating member that electrically insulates between the positive electrode current collector 16 and the sealing plate 20. As shown in FIG. 3A, the current collector-side insulator 54 is a positive electrode except for the −Z side surface that is the surface on the electrode body 14 side of the positive electrode current collector 16 and the inner wall surface of the current collector through hole 52. The outer peripheral surface of the current collector 16 is covered. The current collector-side insulator 54 can be formed of a resin component. Alternatively, a predetermined outer peripheral surface of the positive electrode current collector 16 may be resin-coated.

  The sealing plate side insulator 56 is an insulating member that electrically insulates between the positive terminal mounting hole 50 of the sealing plate 20 and the outer peripheral surface of the positive terminal 30. As shown in FIG. 3A, the sealing plate side insulator 56 is a bottom surface of the recess 21 provided on the outer peripheral side of the positive electrode terminal mounting hole 50 and a surface on the −Z side of the flange portion 60 of the positive electrode terminal 30. It arrange | positions along between one surface. The sealing board side insulator 56 can be comprised with a resin component. Instead of this, a predetermined outer peripheral surface of the positive electrode terminal 30 may be resin-coated.

  The external conductive member 34 on the positive electrode side is an aluminum metal plate member. The bolt 36 on the positive electrode side is used to fasten a bus bar that electrically connects terminals of adjacent rectangular secondary batteries. A bolt mounting portion is provided at the −Y side end of the positive electrode side external conductive member 34 to fix the bolt 36, and the + Y side end portion is connected to the positive electrode terminal 30 by a welding process. Thus, by shifting the positions of the positive electrode terminal 30 and the bolt 36, it is possible to prevent torque from being directly applied to the positive electrode terminal 30 when the bus bar is fastened to the external conductive member 34 by the bolt 36. Thereby, the fall of the sealing performance between the positive electrode terminal 30 and the sealing board 20, the damage of the connection part of the positive electrode terminal 30 and the positive electrode electrical power collector 16, etc. can be prevented.

  In the above description, the positive terminal 30 is electrically insulated from the sealing plate 20. However, depending on the case, the positive terminal 30 and the sealing plate 20 may be electrically connected.

  FIG. 3B is a diagram showing a state after performing a welding process between the protruding portion 64 and the external conductive member 34 from the state of FIG. The welding process uses laser welding that irradiates high energy rays. Instead of this, welding means such as resistance welding may be used. The nugget 70 is a welded portion formed by welding between the protruding portion 64 and the external conductive member 34 on the positive electrode side. The nugget 70 is preferably formed within the height of the protrusion 64. Thereby, it is possible to suppress the influence of the heat of welding on the sealing plate side insulator 56 which is a resin component or the like, and it is possible to suppress thermal deformation and characteristic change of the sealing plate side insulator 56.

  The positive electrode terminal 30 made of aluminum metal is welded to the positive electrode-side external conductive member 34 made of aluminum metal at the end on the + Z side. Thus, the welding process on the positive electrode terminal 30 side is performed between aluminum-based metals, and corrosion due to contact with different metals does not occur. In addition, since the melting point of aluminum-based metals is relatively low, heat generated by welding between aluminum-based metals is relatively low, and aluminum-based metals have lower thermal conductivity than copper-based metals. There is little influence on the insulating member 32, the current collector side insulator 54, and the sealing plate side insulator 56.

  FIG. 4 is a view in which the periphery of the negative electrode terminal 40 is extracted from the top view of the secondary battery 10. The directions of the X axis and the Y axis in FIG. 4 are the same as those in FIG. As shown in FIG. 1, the periphery of the positive electrode terminal 30 and the periphery of the negative electrode terminal 40 are symmetrical with respect to the Y axis. Therefore, FIG. 4 is the same as FIG. 2 except that the X-axis and Y-axis directions are opposite. FIG. 4 shows a sealing plate 20, a negative electrode terminal 40, a negative electrode-side insulating member 42, a negative electrode-side external conductive member 44, and a negative electrode-side bolt 46. FIG. 5 is a sectional view taken along line BB in FIG. FIG. 5A shows a state before the welding process of the negative electrode terminal 40 and the external conductive member 44, and FIG. 5B shows a state after the welding process.

  Comparing FIG. 5 with FIG. 3, the element on the negative electrode terminal 40 side is different from the element on the positive electrode terminal 30 side in the negative electrode terminal 40.

  The negative electrode terminal mounting hole 51 has the same contents as the positive electrode terminal mounting hole 50, and the current collector through hole 53 provided in the negative electrode current collector 18 is the same as the current collector through hole 52 provided in the positive electrode current collector 16. Content. The concave portion 21 is the same as that described on the positive electrode side.

  The current collector-side insulator 55 on the negative electrode side has the same contents as the current collector-side insulator 54 on the positive electrode side. The negative electrode side sealing plate side insulator 57 has the same contents as the positive electrode side sealing plate side insulator 56.

  The external conductive member 44 on the negative electrode side is an aluminum-based metal plate member, like the external conductive member 34 on the positive electrode side. The negative side bolt 46 has the same contents as the positive side bolt 36.

  In addition, a portion 43 where the sealing plate 20 and the insulating member 42 on the negative electrode side are fitted to each other is provided on the lower side which is the −Z direction side of the bolt 46. By providing the fitting portion 43, it is possible to suppress the torque from being applied to the negative terminal 40 when a fastening process is performed between the bolt 46 and another member. In FIG. 3 on the positive electrode terminal 30 side, illustration of the fitting portion is omitted, but the sealing plate 20 and the positive electrode side insulating member 32 are fitted to each other on the lower side of the bolt 36 similarly to the negative electrode terminal 40 side. It is preferable to provide a portion to perform.

  Thus, except for the negative electrode terminal 40, the other elements have the same contents as the corresponding elements on the positive electrode terminal 30 side, and thus further description is omitted.

  The negative electrode terminal 40 includes a flange portion 80 and an annular insertion portion 82 connected to one surface which is a surface on the −Z side of the flange portion 80. The flange portion 80 has a larger outer area than the opening area of the negative electrode terminal mounting hole 51, and is a flange-shaped portion disposed on the outer surface side of the sealing plate 20 in the negative electrode terminal 40. The outer diameter of the flange portion 80 is smaller than the inner diameter of the recess 21 provided in the sealing plate 20. The annular insertion portion 82 is a portion that is inserted into the negative electrode terminal mounting hole 51 and the current collector through hole 53 in the negative electrode terminal 40. The recess 21 is not an essential configuration.

  The negative electrode terminal 40 is significantly different from the positive electrode terminal 30 in terms of material structure. The negative terminal 40 has a first region 90 made of a copper-based metal and a second region 92 made of an aluminum-based metal. The surface of the negative electrode terminal 40 may be subjected to metal plating such as nickel plating. The flange portion 80 has a structure in which a first region 90 and a second region 92 are laminated. The other surface side that is the + Z side surface of the flange portion 80 is the second region 92 of the aluminum-based metal, and the one surface side that is the surface of the −Z side is the first region of the copper-based metal. An annular insertion portion 82 is formed by being connected to the copper-based metal first region 90 on one surface side of the flange portion 80. The annular insertion portion 82 is configured by a first region 90 made of copper-based metal.

FIG. 6 is a view showing the negative electrode 40 extracted. However, this is the state before the tip 86 is crimped. A boundary portion C between the first region 90 and the second region 92 is provided in the flange portion 80. The boundary portion C extends along the Z direction, which is the thickness direction of the flange portion 80, from one surface that is the + Z side surface of the flange portion 80 toward the other surface that is the −Z side surface. It is preferable to be provided in a portion equal to or less than 50% of the thickness t ₀ of 80. In other words, a second region 92 thickness t 5 percent or less in thickness t ₁ of ₀ is an aluminum-based metal of the flange portion 80, the first region 90 of the thickness t ₂ is 5% or more of copper metal It is. As a result, the boundary C can be appropriately separated from the protrusion 84. The boundary portion C extends from one surface that is the + Z side surface of the flange portion 80 toward the other surface that is the −Z side surface along the Z direction that is the thickness direction of the flange portion 80. More preferably, the thickness t ₀ of the flange portion 80 is 20% to 40%.

In particular, the entire weld nugget 74 is accommodated in the protrusion 84, that is, the weld nugget 74 does not reach the flange 80, and the ratio of the thickness t ₁ to the thickness t ₀ of the flange 80 is 20% to 40%. The following is preferable. With such a configuration, it is possible to suppress the adverse effect of heat generated when welding the external conductive member 44 and the negative electrode terminal 40 on the sealing plate-side insulator 57 and further improve the conductivity of the negative electrode terminal 40. It becomes possible.

  FIG. 7 is a diagram illustrating some modified examples of the shapes of the first region 90 and the second region 92 in the negative electrode 40.

  FIG. 7A shows an example in which the outer diameter of the second region 92 is smaller than the outer diameter of the first region 90 on the outer peripheral side 100 of the flange portion 80, and the first region 90 is on the outermost diameter side. That is, the side surface of the second region 92 in the flange portion 80 is covered with the first region 90. Conversely, (b) is an example in which the outer diameter of the second region 92 is larger than the outer diameter of the first region 90 on the outer peripheral side 101, and the second region 92 is the outermost diameter side. That is, the side surface of the first region 90 in the flange portion 80 is covered with the second region 92. By using these examples, the adhesion between the first region 90 and the second region 92 on the outer peripheral side of the flange portion 80 is improved, and the occurrence of damage at the boundary portion C can be suppressed.

  FIG. 7C shows an example in which the first region 90 protrudes toward the second region 92 in the central region 102 of the flange portion 80. Conversely, (d) is an example in which the second region 92 protrudes toward the first region 90 in the central region 103. By using these examples, the adhesion between the first region 90 and the second region 92 is improved at the center of the flange portion 80. In (c), since the ratio of the 1st area | region 90 with high electroconductivity can be enlarged, the electrical resistance of the negative electrode terminal 40 is reduced.

  FIG. 7E shows an example in which the diameter of the upper end portion of the insertion portion 82 is increased in the connection region 104 where the insertion portion 82 extends from the flange portion 80. Thereby, the electrical resistance in the connection area | region 104 of the flange part 80 and the insertion part 82 is reduced, and mechanical strength improves.

  Returning to FIG. 5A again, the protrusion 84 provided on the surface on the + Z side of the flange 80 is a weld end when the negative electrode terminal 40 and the negative electrode-side external conductive member 44 are welded. The protrusion 84 is continuously provided in an annular shape. Instead of this, a plurality of projections 84 arranged in an annular shape may be provided. Or it can also be set as the column shape which does not have a recessed part in an upper surface. The protrusion 84 is a second region 92 made of an aluminum-based metal, and the negative electrode-side external conductive member 44 is also an aluminum-based metal.

  The distal end portion 86 provided at the −Z side distal end portion of the insertion portion 82 is expanded in diameter on the negative electrode current collector 18 and is crimped on the negative electrode current collector 18. The tip 86 protrudes continuously in an annular shape with a predetermined thickness. It may replace with this and may provide a plurality of tip parts 86 arranged in an annular shape. The distal end portion 86 is a first region 90 made of a copper-based metal. In addition, it is preferable to further weld and connect the crimped tip portion 86 and the negative electrode current collector 18.

  FIG. 5B is a diagram illustrating a state after the negative electrode terminal 40 and the external conductive member 44 are welded from the state of FIG. Laser welding is used for the welding process. Instead of this, other welding means such as resistance welding may be used. The nugget 74 is a welded portion formed by welding between the protrusion 84 and the external conductive member 44 on the negative electrode side.

  The negative electrode terminal 40 is welded to the external conductive member 44 on the negative electrode side of the aluminum-based metal using the projection 84 of the aluminum-based metal at the end on the + Z side. Thereby, the connection between the negative electrode terminal 40 and the external conductive member 44 on the negative electrode side becomes stronger, and the secondary battery 10 with high reliability is obtained.

  The boundary portion C between the first region 90 and the second region 92 in the negative electrode terminal 40 is further on the + Z side than the outer surface that is the + Z side surface of the sealing plate 20 and is exposed to the nonaqueous electrolyte. There is no. Therefore, even if the potential of the negative electrode becomes a low value, it is possible to reliably prevent the aluminum-based metal constituting the second region 92 and lithium contained in the non-aqueous electrolyte from alloying.

  In addition, since the melting point of the aluminum-based metal is relatively low, heat generated by welding between the aluminum-based metals is also relatively small. Furthermore, since the aluminum-based metal has lower thermal conductivity than the copper-based metal, it is possible to suppress the heat generated during welding from being transmitted through the negative electrode terminal 40 and adversely affecting the negative-side sealing plate-side insulating member 57 such as a resin component. .

  Since the boundary portion C between the first region 90 and the second region 92 is located at a position away from the distal end portion 86 where the caulking process is performed, the stress due to the caulking process is prevented from being applied to the boundary portion C. it can.

  Copper-based metals have higher mechanical strength than aluminum-based metals. In the negative electrode terminal 40, the portions (the lower surface portion of the flange portion 80, the insertion portion 82, and the tip portion 86) that sandwich the sealing plate 20 and the negative electrode current collector 18 are made of copper-based metal. The electric body 18 is fixedly connected to the sealing plate 20 more firmly.

  The sealing plate side insulating member 57 includes a main body portion 57a disposed between the lower surface of the flange portion 80 and the upper surface of the sealing plate 20, and a peripheral wall 57b formed at the peripheral edge portion of the main body portion 57a. And the boundary part C is located below rather than the upper end part of the surrounding wall 57b. Thereby, the boundary C is covered with the peripheral wall 57b. According to such a configuration, when moisture is generated in the vicinity of the negative electrode terminal due to condensation or the like, it is possible to prevent water droplets or a water film from being present across the copper metal part and the aluminum metal part. . Therefore, corrosion of a portion made of an aluminum metal can be suppressed.

  An assembled battery can be configured by connecting a plurality of the secondary batteries 10 described above. FIG. 8 is a plan view showing a connection method in two secondary batteries 112 and 114 arranged adjacent to each other in the assembled battery 110. Here, the negative electrode terminal 40 of the secondary battery 112 on one side of the two adjacent secondary batteries 112 and 114 and the positive electrode terminal 30 of the secondary battery 114 on the other side face each other along the X direction. Be placed. A bus bar 116 is used to connect the negative terminal 40 and the positive terminal 30. The bus bar 116 is a kind of external conductive member. Bus bar 116 is formed of an aluminum-based metal. In other words, the other end of the bus bar 116 as an external conductive member whose one end is welded to the negative electrode terminal 40 of the secondary battery 112 on one side of the adjacent secondary batteries 112 and 114 is the secondary battery on the other side. 114 is connected to the positive terminal 30 by welding. By repeating this, it is possible to obtain the assembled battery 110 in which the secondary batteries 10 are connected in series in a predetermined number.

  Although the case where the plurality of secondary batteries 10 are connected in series is described in FIG. 8, when the plurality of secondary batteries 10 are connected in parallel to each other, the respective positive terminals of the two secondary batteries 112 and 114 adjacent to each other. 30 are sequentially connected by an external conductive member that is a positive electrode side bus bar, and the negative electrode terminals 40 are sequentially connected by an external conductive member that is a negative electrode side bus bar.

  10, 112, 114 Secondary battery, 12 exterior body, 14 electrode body, 16 positive current collector, 18 negative current collector, 20 sealing plate, 21 recess, 22 gas discharge valve, 24 sealing plug, 30 positive terminal, 32 (positive electrode side) insulating member, 34 (positive electrode side) external conductive member, 36 (positive electrode side) bolt, 40 negative electrode terminal, 42 (negative electrode side) insulating member, 43 fitting portion, 44 (negative electrode side) external conductive member 46 (negative electrode side) bolt, 50 positive electrode terminal mounting hole, 51 negative electrode terminal mounting hole, 52 (positive electrode) current collector through hole, 53 (negative electrode) current collector through hole, 54 (positive electrode) current collector side insulator, 55 (negative electrode) current collector side insulator, 56 (positive electrode side) sealing plate side insulator, 57 (negative electrode side) sealing plate side insulator, 60 (positive electrode terminal) flange portion, 62 (positive electrode terminal) insertion portion, 64 (positive terminal) projection, 66 ( The tip part of the pole terminal, 70, 74 nugget, 80 (negative electrode terminal) flange part, 82 (negative electrode terminal) insertion part, 84 (negative electrode terminal) projection part, 86 (negative electrode terminal) tip part, 90th 1 region, 92 2nd region, 100, 101 outer peripheral side, 102, 103 center region, 104 connection region, 110 assembled battery, 116 bus bar.

Claims (8)

An electrode body having a positive electrode and a negative electrode;
An exterior body having an opening and containing the electrode body;
A sealing plate for sealing the opening of the exterior body;
A positive electrode terminal attached to the sealing plate and electrically connected to the positive electrode;
A negative electrode terminal inserted into a negative electrode terminal mounting hole provided in the sealing plate via a negative electrode side insulating member, and electrically connected to the negative electrode;
With
On the negative terminal side,
A negative electrode current collector that electrically connects the negative electrode and the negative electrode terminal;
An external conductive member made of an aluminum-based metal connected to the negative electrode terminal;
Is provided,
The negative electrode current collector has a current collector through-hole into which the negative electrode terminal is inserted,
The negative terminal is
A flange portion having an outer area larger than an opening area of the negative electrode terminal mounting hole and disposed on an outer surface side of the sealing plate, and an insertion portion connected to one surface of the flange portion, the negative electrode terminal Including an insertion portion inserted into the mounting hole and the current collector through-hole and connected to the negative electrode current collector on the tip side;
A first region composed of a copper-based metal and a second region composed of an aluminum-based metal;
The insertion portion is configured by the first region, a boundary portion between the first region and the second region is provided in the flange portion, and the external conductive member is connected to the second region; Next battery.   The secondary battery according to claim 1, wherein a protrusion is formed on the other surface of the flange portion.   The secondary battery according to claim 2, wherein the protruding portion of the flange portion is connected to the external conductive member.   The boundary portion is provided in a portion of 20 to 40% of the thickness of the flange portion from the other surface of the flange portion toward the one surface in the thickness direction of the flange portion. The secondary battery according to any one of 1 to 3.   The secondary battery according to claim 1, further comprising a bolt portion connected to the negative electrode terminal via the external conductive member.   The secondary battery according to claim 1, wherein the connection is a welding connection. The negative electrode side insulating member has a main body portion disposed between the flange portion and the sealing plate, and a peripheral wall provided at a peripheral edge portion of the main body portion,
The secondary battery according to claim 1, wherein the boundary portion is disposed below an upper end of the peripheral wall. An assembled battery configured by connecting a plurality of the secondary batteries according to any one of claims 1 to 4, 6, and 7,
An assembled battery in which the other end portion of the external conductive member having one end connected to the negative electrode terminal of the secondary battery on one side in the adjacent secondary battery is connected to the positive electrode terminal of the secondary battery on the other side.

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