JP6639112B2 - Lead tab connection structure and connector for laminated battery - Google Patents

Description

  The present invention relates to a technique for electrically connecting lead tabs of a laminated battery such as a lithium ion secondary battery, and more specifically, the connection between lead tabs and the connection between lead tabs and terminals or bus bars are firmly strengthened. The present invention relates to a connection structure and a connection tool that can be used.

  The laminate type lithium ion secondary battery has an aluminum lead tab on the positive electrode and a copper or nickel lead tab on the negative electrode. The secondary batteries are used in layers depending on the desired capacity. The lead tabs of the superposed batteries are joined by ultrasonic welding, for example, as disclosed in Patent Document 1 below. The joining between the lead tab and the bus bar is also performed by ultrasonic welding, for example, as disclosed in Patent Document 2 below.

Japanese Patent No. 5252871 JP 2005-222788 A

  However, ultrasonic welding generates ultrasonic vibrations in a state where the metals to be joined are superimposed on each other and causes atomic bonding at the joining interface. However, impurities such as an oxide film and dirt are present on the surface of the joined metals. They may remain at the bonding interface. For this reason, the part joined by ultrasonic welding may come off by vibration even if it is intended to obtain good stability. Particularly, when the metal to be joined is aluminum, there is a high possibility that accidental separation of the joining portion occurs due to the presence of a tough oxide film, and it is difficult to join with good stability.

  Therefore, an object of the present invention is to make it possible to easily perform strong electrical connection of a lead tab.

  Means for that is a lead tab connection structure of the laminate type battery for electrically connecting the lead tab of the laminate type battery to another member to be superimposed thereon, wherein a fitting shaft portion penetrating the lead tab is erected on the support plate portion. A pin member, and a washer member having a hole portion into which the fitting shaft portion of the pin member is inserted via the lead tab and a plate portion opposed to the support plate portion with the lead tab interposed therebetween, A lead tab connection structure for a laminate type battery having a lead portion formed between a fitting shaft portion and the hole portion by plastic deformation of the lead tab by fitting of the fitting shaft portion, and a rising portion closely contacting the hole portion.

  Another means for solving the problem is a pin member in which a fitting shaft portion penetrating through a lead tab of a laminated battery is erected on a support plate portion, and the fitting shaft portion of the pin member passes through the lead tab. A washer having a hole to be inserted and a plate facing the support plate with the lead tab interposed therebetween, wherein the lead tab is inserted between the insertion shaft and the hole by the insertion of the insertion shaft. Is a lead tab connector for a laminate type battery, which is formed by plastic deformation and is provided with a margin for forming a rising portion which is in close contact with the hole.

  The portion of the lead tab into which the insertion shaft portion of the pin member pierces may be an unopened state or a state having a pilot hole smaller in diameter than the insertion shaft portion.

  In these configurations, when the insertion shaft portion of the pin member is inserted into the hole of the washer member from above the lead tab to be connected and the lead tab is sandwiched between the support plate portion of the pin member and the plate portion of the washer member, the lead tab The insertion shaft that penetrates through and penetrates through the rising portion formed on the lead tab so that the insertion shaft and the hole are in close contact with each other to secure a wide contact area.

  According to the present invention, by pinching the lead tab by the support plate portion of the pin member and the plate portion of the washer member, and by pinching the rising portion obtained by plastic deformation by the insertion shaft portion of the pin member and the hole of the washer member, By vibrating, of course, a strong coupling state that does not come off even when trying to separate can be obtained. Due to this robustness, a durable and reliable electrical connection state is obtained. In addition, since the connection operation can be performed by cold forging by relatively moving the pin member and the washer member, the connection operation is easier and the cost can be suppressed as compared with the case of performing the ultrasonic welding. In addition, since a wide contact area can be obtained, conductivity is good.

The perspective view of a lead tab and a connection tool. The perspective view of an assembled battery. FIG. 2 is an explanatory diagram illustrating a schematic structure of a lithium ion secondary battery. The perspective view of a lead tab connection structure. Sectional drawing of a lead tab connection structure. The perspective view of a connection tool. FIG. 4 is a partial cross-sectional front view of a lead tab and a connection tool. The front view with a partial cross section which shows a process. Sectional drawing which shows a forged state. FIG. 4 is a partial cross-sectional side view of a connection state between a lead tab and a terminal member. FIG. 10 is a partial cross-sectional side view of a connection state between a lead tab and a terminal member according to another example. FIG. 9 is a partial cross-sectional front view of a lead tab and a connection tool according to another example.

One embodiment for carrying out the present invention will be described below with reference to the drawings.
FIG. 1 is an exploded perspective view showing a connector 21 for electrically connecting a lead tab 12 of a lithium ion secondary battery 11 as a laminated type battery, and FIG. It is a perspective view of the assembled battery 13 connected. As shown in these drawings, the lead tab connection structure of the present invention connects the lead tabs 12 or connects the lead tab 12 and the terminal member 14.

  First, the schematic structure of the lithium ion secondary battery 11 will be briefly described with reference to FIG. The lithium ion secondary battery 11 includes a sheet-like positive electrode 15 having an active material provided on both front and back surfaces of a current collector made of a metal foil, and a negative electrode 16 with a separator 17 interposed therebetween. Each of the lead tabs 12 is connected to one end of the negative electrode 16 and a rectangular plate, and is covered with a laminate film 18 together with an electrolytic solution (not shown). The lead tab 12a of the positive electrode is made of aluminum, and the lead tab 12b of the negative electrode is made of copper or nickel. The thickness of these lead tabs 12 is appropriately set and is, for example, about 0.1 mm to 0.5 mm.

  In the illustrated example, an example is shown in which one of two opposite sides of the lithium ion secondary battery 11 is provided with a positive lead tab 12a and the other is provided with a negative lead tab 12b. Numeral 11 may be one provided with positive and negative electrode lead tabs arranged on the same side.

  Next, the connection structure of the lead tab 12 and the connection tool 21 will be described.

  Since the lithium-ion secondary battery 11 has the above-described configuration, in order to connect a plurality of stacked lithium-ion secondary batteries 11 in series as shown in FIG. 2, the overlapping lead tabs 12 need to have a positive electrode, a negative electrode, a positive electrode, or The negative electrode, the positive electrode, and the negative electrode are arranged in this order, and both ends of the series connection, that is, the lead tabs 12 are connected to each other except for one of the lead tabs 12 of the lithium ion secondary battery 11 at the upper end and the lower end in the overlapping direction. A terminal member 14 holding an electric wire 19 is connected to the lead tab 12.

  FIG. 4 is a perspective view of a connection structure in which the lead tabs 12 are connected to each other using the connection tool 21, and FIG. 5 is a longitudinal sectional view thereof. As shown in these figures, the connection structure is obtained by cold forging using the pin member 22 and the washer member 23. Specifically, the connection structure is such that a pin member 22 having a fitting shaft portion 24 penetrating through the lead tab 12 is erected on the support plate portion 25, and the fitting shaft portion 24 of the pin member 22 is inserted with the lead tab 12 interposed therebetween. Member 23 having a hole 27 and a plate 27 facing the support plate 25 with the lead tab 12 interposed therebetween, and the lead tab is inserted between the insertion shaft 24 and the hole 26 by the insertion of the insertion shaft 24. There is provided a rising portion 28 formed by plastically deforming the portion 12 and closely contacting the hole portion 26.

  A portion of the pin member 22 protruding from the washer member 23 has a large-diameter portion 22a that is compression-molded to a diameter larger than the hole 26 of the washer member 23. On the top surface of the large-diameter portion 22a, a portion of the pin member 22 protruding from the washer member 23 is protruded to the outer peripheral side to reliably form the large-diameter portion 22a, and a rising portion 28 is formed in the hole of the washer member 23. A depression 29 is formed in close contact with the portion 26. In this manner, the base of the fitting shaft 24, which forms the large-diameter portion 22a and makes the rising portion 28 adhere to the hole 26, has a shape having a corner radius from before joining. On the surface of the pin member 22 on the side of the fitting shaft portion 24 of the support plate portion 25, irregularities for increasing the contact area with the lead tab 12 and increasing the contact resistance are provided by the formation of the convex portions 25a.

  That is, as shown in FIGS. 6 and 7, the connector 21 having such a connection structure includes a pin in which a fitting shaft portion 24 penetrating the lead tab 12 of the lithium ion secondary battery 11 is erected on the support plate portion 25. A member 22 and a washer 23 having a hole 26 into which the fitting shaft 24 of the pin 22 is inserted via the lead tab 12 and a plate 27 facing the support plate 25 with the lead tab 12 interposed therebetween. A space is provided between the fitting shaft portion 24 and the hole portion 26 to form a rising portion 28 that is formed by plastically deforming the lead tab 12 by the fitting of the fitting shaft portion 24 and is in close contact with the hole portion 26.

  The pin member 22 is formed of a solid, conductive, cold forgeable material. For this, an appropriate metal such as copper is used. The surface may be subjected to a surface treatment such as nickel plating if necessary.

  The support plate portion 25 of the pin member 22 has a disk shape, and a chamfered surface 25b is formed on the head side, that is, on the outer peripheral edge on the opposite side of the fitting shaft portion 24 (the lower surface side in FIG. 6). On the surface of the support plate portion 25 on the side of the fitting shaft portion 24, a convex portion 25a is formed as unevenness. The protruding portion 25a increases the contact area with the lead tab 12 and prevents relative movement as described above, and is configured by a protruding portion 25a that is discontinuous in the circumferential direction. More specifically, a plurality of arc-shaped convex portions 25a concentrically extending around the axis of the fitting shaft portion 24 are formed so as to be divided in the circumferential direction. The unevenness may be formed by forming a concave portion such as a groove.

  The fitting shaft portion 24 has a circular cross section and stands upright at the center of the support plate portion 25. The fitting shaft portion 24 is formed to have an appropriate length according to a member to be connected, and has a flat surface 24a, a tapered cone surface 24b, and a shaft portion 24c in order from the tip.

  When the flat surface 24a is inserted into the washer member 23, a portion protruding from the washer member 23 is protruded to the outer peripheral side as shown in FIG. It is the part that is formed. The tapered cone surface 24 b reduces the area of the flat portion 24 a at the tip to make it easier to pierce the lead tab 12, and has a relatively large margin between the tapered cone surface 24 b and the hole 26 of the washer member 23, that is, the tip of the fitting shaft 24. This is to provide a margin between the two when the lead tabs 12 enter the hole 26 of the washer member 23 and allow a part of the lead tab 12 to break through. The shaft portion 24c has a columnar shape with a slightly larger diameter toward the lower end, that is, toward the base, and a rounded corner portion 24d having an arc-shaped cross section is formed all around the boundary portion with the support plate portion 25 which is the base portion. ing.

  The washer member 23 is also formed of a material that has conductivity and can be cold forged. The washer member 23 has an annular plate portion 27 and a central hole portion 26 of the plate portion 27. The size and thickness of the plate portion 27 are appropriately set. The size of the hole 26 is, for example, slightly larger than the diameter of a portion of the fitting shaft portion 24 excluding the lower portion of the corner radius portion 24d, and the size of the fitting portion 24 and the thickness and the number of the lead tabs 12 described above depend on the thickness. It is a size that can afford such a margin.

  When the pin member 22 and the washer member 23 having such a configuration are fixed to the lead tab 12, the above-described lead tab connection structure is obtained.

  To connect the lead tabs 12, as shown in FIG. 8, the two superposed lead tabs 12 are placed on the pin member 22 with the fitting shaft portion 24 facing upward, and the washer is placed on the lead tab 12. The member 23 is placed, and the washer member 23 is hit with a punch 51 from above. The joining portion of the lead tab 12 is in an unopened state.

  The lowering of the punch 51 causes the washer member 23 and the lead tab 12 to move toward the pin member 22, and at this time, a portion corresponding to the hole 26 of the washer member 23 comes into strong contact with the fitting shaft portion 24 of the pin member 22. As a result, the portion of the lead tab 12 where the fitting shaft portion 24 abuts is broken, and the fitting shaft portion 24 is pierced, and as shown by the phantom line in FIG. It is formed. By further lowering the punch 51, the rising portion 28 of the lead tab 12 further rises along the shaft portion 24c of the fitting shaft portion 24, and expands to the outer peripheral side so as to enlarge the hole portion 26 of the washer member 23. It closely adheres to the hole 26. With the subsequent drop of the punch 51, the base of the rising portion 28 is deformed by the corner round portion 24 d at the lower end of the fitting shaft portion 24 so as to be pushed toward the upper outer periphery.

  On the other hand, the tip side portion of the fitting shaft portion 24 is compression molded according to the shape of the molding surface 52 in the punch 51. The molding surface 52 of the punch 51 has a height lower than the height of the fitting shaft portion 24 and has a substantially inverted mortar shape in which the inner diameter of the lower end is larger than the diameter of the hole 26 of the washer member 23. That is, the tapered surface 52a has a larger diameter at the lower end and a smaller diameter as it goes upward. The diameter of the lower end of the molding surface 52 is set to be larger than the diameter of the enlarged hole 26 in consideration of the enlargement of the hole 26 of the washer member 23.

  In the center of the ceiling surface at the upper end position of the tapered surface 52a of the molding surface 52, a substantially hemispherical depression forming portion 52b is formed. Since the tip of the fitting shaft portion 24 has the flat portion 24 a, the recessed portion forming portion 52 b can stably form the recessed portion 29 at the tip of the fitting shaft portion 24. Since the lower end of the molding surface 52 of the punch 51 is formed to be larger than the diameter of the hole 26 of the washer member 23, a portion of the fitting shaft portion 24 of the pin member 22 protruding from the washer member 23 is provided. An approximately flat spherical large-diameter portion 22a formed by compression molding to a diameter larger than that of the hole 26 is formed.

  Since the depression 29 is formed as described above, the portion of the fitting shaft portion 24 protruding from the washer member 23 is made to protrude better on the outer peripheral side than the expanded hole portion 26, and the large large-diameter portion 22a is reliably formed. In addition to this, the rising portion 28 can be more positively brought into close contact with the hole 26.

  When such cold forging is completed, the support plate portion 25 of the pin member 22 and the plate portion 27 of the washer member 23 are combined with each other by the synergistic action of the corner radius portion 24d, the large diameter portion 22a, and the depression portion 29. Strongly. The support plate 25 of the pin member 22 is formed with the convex portion 25a, so that a large contact area can be secured. Further, since the convex portion 25a is discontinuous in the circumferential direction, relative rotation between the convex portion 25a and the lead tab 12 is achieved. Is well prevented.

  The joining of the lead tab 12 by the pin member 22 and the washer member 23 may be performed in accordance with a desired amount of current or the size of the lead tab 12, for example, in addition to the three shown in FIG. This is performed using an appropriate number of connection tools 21.

  In such a connection structure, the support plate portion 15 of the pin member 22 and the plate portion 27 of the washer member 23 strongly sandwich the lead tab 12, and the fitting shaft portion 24 and the hole portion 26 are formed on the lead tab 12. The portion 28 is pressed and spread to the outer peripheral side and is tightly sandwiched to secure a wide contact area. Therefore, good conductivity is obtained.

  In addition, the connection by the connecting tool 21 can be performed only by inserting the insertion shaft portion 24 of the pin member 22 from above the lead tab 12 into the hole portion 26 of the washer member 23 and compressing the same. It is easier to work than.

  In addition, since the lead tab 12 is strongly sandwiched between the support plate portion 25 and the plate portion 27 and the large-diameter portion 22a formed by compression molding is prevented from coming off, joining by vibration that has occurred in joining by ultrasonic welding is performed. Not only separation of the surfaces but also loosening can be prevented, and a reliable connection state can be maintained for a long period of time. The large-diameter portion 22a formed by compression-molding the fitting shaft portion 24 of the pin member 22 can be surely formed by forming the depressed portion 29, which is a hemispherical concave portion. The hole 26 of the washer member 23 is enlarged by cooperation with the corner rounded portion 24d of the portion, and the inner peripheral edge of the hole 26 to be plastically deformed is strongly pressed from above, so that the bonding strength is extremely high. high.

  The corner rounded portion 24d of the fitting shaft portion 24 also serves to increase the standing strength of the fitting shaft portion 24, so that not only high strength is obtained as described above, but also the fitting shaft portion 24 is broken at the time of forging connection. It is also possible to prevent the occurrence of defects.

  In addition, since the connection structure of the lead tab is a structure obtained by physically connecting the connection tools 21 using plastic deformation or compression molding, a strong electrical connection state can be obtained regardless of materials such as aluminum. Also have.

  The connection described above is the same when the terminal member 14 is connected to the lead tabs 12 of the lithium ion secondary battery 11 at both ends of the series connection in the battery pack 13 shown in FIG. In this case, one lead tab 12 and one or more terminal members 14 are joined by the pin member 22 and the washer member 23.

  FIG. 10 is a cross-sectional view showing a connection state between the lead tab 12 and the terminal member 14. That is, instead of the lower lead tabs 12 shown in FIGS. 7 and 8 for joining the lead tabs 12, the leading end connection portions 14 a of the connection terminals 14 are overlapped and joined. The connection terminal 14 has a known configuration including an annular distal end connection portion 14 a having a hole 14 b at the center and a tubular electric wire connection portion 14 c for connecting the electric wire 19. The hole portion 14b of the distal end connection portion 14a has a size that allows the insertion shaft portion 24 of the pin member 22 to be inserted.

  The configurations of the pin member 22 and the washer member 23 are the same as described above.

  The distal end connecting portion 14a of the terminal member 14 is placed under the lead tab 12 with the electric wire connecting portion 14c facing down, and the fitting shaft portion 24 of the pin member 22 corresponds to the hole 14b of the distal end connecting portion 14a. Then, the washer member 23 is placed on the lead tab 12 and cold forging is performed using a punch in the same manner as described above. As a result, the same connection structure as described above can be obtained, and the same operation and effect can be obtained. Since they overlap, detailed description thereof will be omitted. The terminal member 14 may be superimposed on the lead tab 12 not on the lower surface but on the upper surface.

  When joining the terminal member 14 to the lead tab 12, the washer member 23 of the connecting tool 21 can be used as the distal end connecting portion 14 a of the terminal member 14. In other words, the wire connecting portion 14c for connecting the wire 19 can be formed integrally with the washer member 23.

  FIG. 11 shows a connection structure of the lead tab 12 according to the configuration. That is, the size of the hole 14b in the distal end connection portion 14a of the terminal member 14 as the washer member of the present invention is set so as to have a predetermined relationship with the fitting shaft portion 24 of the pin member 22 as described above. Have been.

  In this case, the leading end connection portion 14a of the terminal member 14 may be overlapped on the lead tab 12. When the forging shaft portion 24 of the pin member 22 is applied from below to perform punching on the terminal member 14 and perform cold forging, a connection structure similar to that described above is obtained, and similar operations and effects are exerted. Since they overlap, detailed description thereof will be omitted.

  In this configuration, in particular, the number of components can be reduced, so that the cost can be reduced and the weight can be reduced.

  In the above example, the example in which the connecting tool 21 is fixed to the unopened portion of the lead tab 12 is shown. However, as shown in FIG. 21 may be fixed. The same applies to the case where the lead tabs 12 are connected to each other as well as the case where the lead tabs 12 and the terminal members 14 are connected as shown in FIGS.

  It is preferable that the pilot hole 12c has a circular shape equal to or smaller than the flat portion 24a at the tip of the pin member 22. In this case, the pilot hole 12c serves as a start when the fitting member 24 is pierced, so that the shape of the upper edge of the rising portion 28 can be made stable and beautiful.

In correspondence between the configuration of the present invention and the configuration of the above embodiment,
The laminated battery of the present invention corresponds to the above-described lithium ion secondary battery 11,
Similarly,
Other members correspond to the lead tab 12 and the terminal member 14 of the other lithium ion secondary battery 11,
The above-described configuration is one mode for carrying out the present invention, and the present invention is not limited to only the above-described configuration, and other configurations can be adopted.

  For example, three or more lead tabs may be joined. Another member may be a bus bar or the like in addition to the terminal member 14.

  Further, the portion of the fitting shaft portion 24 protruding from the washer member 23 in the connection structure may be in a state in which the rising portion 28 is firmly pressed against the hole 26 on the outer peripheral side. The unit 29 may be omitted.

  The fitting shaft portion 24 of the pin member may be formed in a polygonal shape in addition to the above-described circular cross-sectional shape.

DESCRIPTION OF SYMBOLS 11 ... Lithium ion secondary battery 12 ... Lead tab 14 ... Terminal member 14a ... Tip connection part 14b ... Hole 14c ... Electric wire connection part 19 ... Electric wire 21 ... Connection tool 22 ... Pin member 22a ... Large diameter part 23 ... Washer member 24 ... Fitting shaft part 24d ... Round corner part 25 ... Support plate part 25a ... Protrusion part 26 ... Hole part 27 ... Plate part 28 ... Rising part 29 ... Depressed part

Claims (11)

A lead tab connection structure of a laminated battery for electrically connecting a lead tab of the laminated battery to another member to be stacked thereon,
A pin member in which a fitting shaft portion penetrating the lead tab is erected on the support plate portion,
A washer member having a hole portion in which the fitting shaft portion of the pin member is inserted via the lead tab and a plate portion facing the support plate portion with the lead tab interposed therebetween,
A lead tab connection structure for a laminate type battery, wherein a rising portion is formed between the fitting shaft portion and the hole portion so that the lead tab is formed by plastic deformation of the fitting shaft portion when the fitting portion is in close contact with the hole portion. Wherein the washer projecting portion than members in the pin member, the lead tab connection structure of a laminate type battery of claim 1 having a large diameter portion which is compressed into a diameter larger than the hole. The fitting shaft portion is solid,
3. A recessed portion formed at a tip of the fitting shaft portion so as to protrude a portion of the pin member that protrudes from the washer member to the outer peripheral side and to make the rising portion adhere to the hole portion. 4. The lead tab connection structure of the laminated battery according to 1. The lead tab connection structure for a laminated battery according to any one of claims 1 to 3, wherein a corner radius portion is provided at a root portion of the fitting shaft portion in the pin member. The lead tab connection structure for a laminated battery according to any one of claims 1 to 4, wherein a surface of the support plate portion on the side of the insertion shaft portion has irregularities discontinuous in a circumferential direction. The lead tab connection structure for a laminated battery according to any one of claims 1 to 5, wherein the washer member is a distal end connection portion of a terminal member having an electric wire connection portion for connecting an electric wire. A pin member in which a fitting shaft portion penetrating the lead tab of the laminated battery is erected on the support plate portion,
A washer member having a hole portion in which the fitting shaft portion of the pin member is inserted via the lead tab and a plate portion facing the support plate portion with the lead tab interposed therebetween,
A lead tab for a laminated battery, wherein a margin is provided between the insertion shaft portion and the hole portion so that the lead tab is formed by plastic deformation by the insertion of the insertion shaft portion to form a rising portion which is in close contact with the hole portion. Fittings. The fitting shaft portion is solid,
At the tip of the fitting shaft portion, a flat portion is formed in which a depressed portion is formed in which a portion protruding from the washer member when inserted into the washer member is protruded to the outer peripheral side and the rising portion is in close contact with the hole portion. The lead tab connector for a laminate type battery according to claim 7, further comprising: 9. The lead tab connector for a laminated battery according to claim 7, wherein a corner radius portion is formed at a root portion of the fitting shaft portion in the pin member. 10. The lead tab connector for a laminated battery according to any one of claims 7 to 9, wherein discontinuous irregularities are formed in a circumferential direction on a surface of the support plate portion on the side of the insertion shaft portion. The lead tab connector for a laminated battery according to any one of claims 7 to 10, wherein a wire connecting portion for connecting a wire to the washer member is integrally formed.

Images