JP5218956B2 - Square sealed battery - Google Patents

Description

  The present invention relates to a prismatic sealed battery, and more particularly to a prismatic sealed battery that does not cause an internal short circuit against external pressure or external impact.

  Various types of batteries are used as power sources for small electronic devices, and small and large-capacity power sources are used as power sources for mobile phones and notebook computers. In recent years, lithium-ion secondary batteries and the like that have a particularly high energy density are used. A square sealed battery using a water electrolyte is used. Also, along with the thinning of electronic devices, batteries are also used because square batteries suitable for thin devices are superior in space efficiency, and complete sealing is essential because they contain nonaqueous electrolytes. Yes.

  FIG. 8 is a schematic diagram illustrating an example of a conventional square sealed battery. Conventionally, a positive electrode and a negative electrode are laminated and wound via a separator on a battery outer can 2 made of aluminum or an alloy thereof, the molded electrode winding element 1 is accommodated, and a battery lid 6 is fitted to the battery outer can 2. After that, laser welding is performed. In the case of this battery, an intermediate insulating polymer plate 5 made of polyethylene resin or polypropylene resin is disposed on the upper part of the electrode winding element 1.

  However, in this structure, in order to connect the electrode winding element 1 to the external negative electrode terminal 8 after the electrode winding element 1 is accommodated in the battery outer can 2, it is necessary to route the electrode winding element 1 to the external negative electrode terminal 8 using a tab. . In that case, it is necessary to weld the negative electrode tab 4 to the external negative electrode terminal 8 after the electrode winding element 1 is housed in the battery outer can 2, and the negative electrode tab 4 needs to be longer than the necessary minimum length. is there. When the negative electrode tab 4 is longer than necessary, the negative electrode tab 4 is stored in a curved state as shown in FIG. 8 when it is finally stored in the battery outer can 2. In order to prevent the negative electrode tab 4 from coming into contact with the battery outer can 2 or the positive electrode tab 3, an intermediate insulating polymer plate 5 is provided. However, the impact or pressure from the outside is applied to the battery outer can 2 alone. In this case, contact between the negative electrode tab 4 and the inner wall of the battery outer can 2 or the positive electrode tab 3 cannot be sufficiently prevented, and a short circuit may occur.

  Patent Document 1 discloses a technique for positioning and accommodating a lead with high accuracy inside an insulating frame by folding a lead (electrode tab) in a meandering manner. If the impact or pressure applied to the battery outer can exceeds a certain value, the battery outer can and the insulating frame are deformed, and it is difficult to completely prevent an internal short circuit.

JP 2003-242957 A

  As already explained, with conventional rectangular sealed batteries, it is difficult to completely prevent internal short circuit due to contact between the negative electrode tab and the inner wall of the battery outer can when external impact or pressure is applied to the battery outer can. .

  Accordingly, an object of the present invention is to provide a prismatic sealed battery with improved reliability by preventing contact between the negative electrode tab and the battery outer can inside due to an external impact or pressure.

In order to solve the above problems, the rectangular sealed battery according to the present invention includes an electrode winding element obtained by laminating a positive electrode plate and a negative electrode plate with a separator interposed between them and a battery cover can together with an electrolyte solution and sealed with a battery lid. in the prismatic sealed battery, the intermediate insulating polymeric plate provided between the battery cover and the electrode winding element, is derived from the negative electrode plate, through the intermediate insulating polymeric sheet, the battery lid side A negative electrode tab having an end bent along the main surface of the battery, and an external negative electrode terminal formed on the battery lid through an insulating portion and provided to conduct inside and outside of the battery lid. the externally negative terminal electrical connection end and said end portion of the negative electrode tab of the by intermediate insulating polymeric plate, and said end portion of the one end and the negative electrode tab of the external negative terminal is pressed It is characterized by that.

  The intermediate insulating polymer plate is composed of a partial plate that is divided into two by a plane perpendicular to the main surface, and at least one of the partial plates is provided with a notch, and the partial plates are joined together to form the negative electrode tab. A through hole may be formed.

  An insertion stopper for setting the insertion position of the intermediate insulating polymer plate may be provided on the inner wall of the battery outer can.

  One or more convex portions are provided in a portion of the external negative electrode terminal that contacts the bent end portion of the negative electrode tab, and the convex portion and the bent end portion of the negative electrode tab have one point or multiple points. It is good to contact with.

  The intermediate insulating polymer plate may be made of any of polyamide, polyimide, phenol resin, polyethylene terephthalate, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride, and polyvinyl fluoride.

  According to the rectangular sealed battery of the present invention, the negative electrode tab extended from the electrode winding element is passed through the intermediate insulating polymer plate, the bent end portion is formed along the upper surface, and the negative electrode tab end portion and the battery lid are formed. By connecting the lower end of the external negative electrode terminal provided to the battery by pressing, electrical connection inside and outside the battery lid can be ensured. As a result, the negative electrode tab does not bend when the battery lid is mounted and fixed, and an internal short circuit due to an external impact can be prevented, thereby providing a highly reliable prismatic sealed battery.

  Next, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic diagram for explaining the structure of a rectangular sealed battery according to the present invention. In the present embodiment, as shown in FIG. 1, after the electrode winding element 1 having the positive electrode tab 3 and the negative electrode tab 4 is inserted into the battery outer can 2, the negative electrode tab 4 is formed in a slit shape at the center of the intermediate insulating polymer plate 5. After being stretched through the hole 21, it is bent. In addition, the electrode winding part of the electrode winding element 1 was typically represented by a two-dot chain line.

  FIG. 2 is a schematic perspective view showing the configuration of the electrode winding element. The positive electrode plate 10 from which the positive electrode tab 3 is drawn out and the negative electrode plate 11 from which the negative electrode tab 4 is drawn out are electrode winding elements wound through a separator 12. In addition, the manufacturing method is the same as that of a well-known winding type lithium ion secondary battery, for example.

  FIG. 3 is a perspective view showing a bending state of the negative electrode tab 4 on the intermediate insulating polymer plate 5. Further, FIG. 7 shows an end bending state of the negative electrode tab according to the present invention, FIG. 7 (a) is a perspective view of a first example of end bending corresponding to FIG. 3, and FIG. 7 (b) is an end bending. It is a perspective view of this 2nd example.

  When the end bending structure as shown in FIG. 3 is formed, the battery lid 6 holding the external negative electrode terminal 8 is pushed downward from above into the opening insertion portion of the battery outer can 2 (FIG. 1) via the insulating portion 7. In this way, it is possible to secure contact with the external negative electrode terminal 8 by tightly contacting and connecting to the end of the negative electrode tab 4 that has already been bent. That is, when the battery lid 6 and the intermediate insulating polymer plate 5 are fixed to the battery outer can 2, a pressing force is generated between the bent end of the negative electrode tab 4 and the lower end of the external negative electrode terminal 8.

  According to such a connection structure, the negative electrode tab 4 is arranged on the intermediate insulating polymer plate 5 without loosening inside the battery and connected to the external negative electrode terminal 8 to ensure conduction to the outside of the battery cover 6. It becomes possible. By the way, although nickel etc. are suitable as a material of the negative electrode tab 4, aluminum etc. may be used if surface treatments, such as a plating process, are given to the contact part with the external negative electrode terminal 8. FIG.

  The positive electrode tab 3 may be pressed against the inner wall of the battery outer can 2, but even if ultrasonic welding is performed, an internal short circuit due to bending does not occur unlike the negative electrode tab 4.

  Further, the intermediate insulating polymer plate 5 maintains the force for pressing the lower end surface of the external negative electrode terminal 8 against the bent end portion of the negative electrode tab 4 in addition to the function of insulating while appropriately holding the electrode winding element 1. A function is necessary. Therefore, as the material, polyamide, polyimide, phenol resin, polyethylene terephthalate, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride, polyvinyl fluoride, and the like are preferable.

(Embodiment 2)
FIG. 4 is a schematic perspective view showing an intermediate insulating polymer plate and a negative electrode tab in Embodiment 2 of the present invention. FIG. 4 (a) is a first example thereof, and FIG. 4 (b) is a second example thereof. An example is shown. This embodiment relates to the invention of claim 2. This is because the intermediate insulating polymer plate is divided into two intermediate insulating polymer plate pieces 5A and 5B, which not only facilitates the penetration of the intermediate insulating polymer plate of the negative electrode tab 4 but also makes the negative electrode tab 4 intermediate. The insulating polymer plate can be stably supported. In the first example of FIG. 4 (a), the negative electrode tab 4 is passed along the recess (notch 21A) of the intermediate insulating polymer plate piece 5A, and then the recess (cut) of the intermediate insulating polymer plate piece 5B. The structure is sandwiched between the notches 21B). In the second example of FIG. 4 (b), the intermediate insulating polymer plate pieces 5A and 5B have notches 21A and 21B that are cut deeply with a narrow width. The negative electrode tab 4 can be fixed when the negative electrode tab 4 is pulled out in a state in which only the negative electrode tab 4 is disposed in the battery outer can and then the intermediate insulating polymer plate piece 5B is disposed in the battery outer can.

  That is, in the case of FIG. 3 in the first embodiment, a gap is formed between the negative electrode tab 4 and the hole 21 of the intermediate insulating polymer plate 5 through which the negative electrode tab 4 passes, and is fixed by bending the end portion. In the embodiment, the negative electrode tab and the inner surface of the hole are brought into close contact with each other, so that the negative electrode tab can be fixed more reliably. In addition, a hole through which the negative electrode tab penetrates is formed by combining an intermediate insulating polymer plate piece (partial plate) having a notch with an intermediate insulating polymer plate piece (partial plate) not having a notch. May be.

(Embodiment 3)
FIG. 5 is a schematic diagram for explaining the rectangular sealed battery according to the third embodiment, and this embodiment relates to claim 3. In the present embodiment, the insertion stopper 9 is provided inside the battery outer can 2 so that the positions of the electrode winding element 1 and the intermediate insulating polymer plate 5 can be manufactured with good control. The positions of the electrode winding element 1 and the intermediate insulating polymer plate 5 can be ensured evenly regardless of the angular deviation at the time of insertion or the insertion pushing pressure, and the length of the negative electrode tab 4 is also minimized. It becomes possible. Therefore, the possibility of contact between the negative electrode tab 4 and the battery outer can 2 and the positive electrode tab 3 is further reduced, and a structure that reduces the possibility of a short circuit can be provided.

(Embodiment 4)
FIG. 6 is a schematic diagram for explaining the rectangular sealed battery according to the fourth embodiment, and this embodiment relates to claim 4. In the present embodiment, a stable contact state is ensured by providing one convex portion in contact with the negative electrode tab 4 at the tip 8A of the external negative electrode terminal 8 provided in the battery lid 6. Moreover, it is a structure which ensures the stable contact by increasing the number of convex parts and making it an embossed shape. Thus, when the tip of the external negative electrode terminal 8 is embossed, the area of the contact portion is increased, and stable conduction to the outer end of the external negative electrode terminal 8 can be obtained.

The schematic diagram explaining the structure of the square sealed battery which concerns on this invention. The typical perspective view explaining the composition of an electrode winding element. The perspective view which shows the bending condition of the negative electrode tab on the intermediate | middle insulating polymer plate which concerns on this invention. The intermediate insulation polymer plate and negative electrode tab in Embodiment 2 of this invention are shown, Fig.4 (a) is the 1st example, FIG.4 (b) is the perspective view which shows the 2nd example. FIG. 4 is a schematic diagram illustrating a rectangular sealed battery according to a third embodiment. FIG. 6 is a schematic diagram illustrating a rectangular sealed battery according to a fourth embodiment. FIG. 7A is a perspective view of a first example of end bending, and FIG. 7B is a perspective view of a second example of end bending, showing the state of bending of the negative electrode tab according to the present invention. The schematic diagram explaining an example of the conventional square sealed battery.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrode winding element 2 Battery exterior can 3 Positive electrode tab 4 Negative electrode tab 5 Intermediate insulation polymer plate 5A, 5B Intermediate insulation polymer plate piece 6 Battery cover 7 Insulation part 8 External negative electrode terminal 8A Tip part 9 Insertion stopper 10 Positive electrode plate 11 Negative electrode plate 12 Separator 21 Hole 21A, 21B Notch

Claims (5)

In a rectangular sealed battery in which an electrode winding element formed by laminating a positive electrode plate and a negative electrode plate via a separator is housed in a battery outer can together with an electrolyte and sealed by a battery lid,
An intermediate insulating polymer plate provided between the electrode winding element and the battery lid ;
The negative electrode plate is derived from, and the through the intermediate insulating polymeric plate, the negative electrode tab having an end portion which is bent along the main surface of the battery lid side,
An external negative electrode terminal formed on the battery lid through an insulating portion and provided to conduct inside and outside of the battery lid ,
Wherein one end of the external negative terminal and the end portion of the negative electrode tab connected electrical,
One end of the external negative electrode terminal and the end of the negative electrode tab are pressed by the intermediate insulating polymer plate .   The intermediate insulating polymer plate is composed of a partial plate that is divided into two by a plane perpendicular to the main surface, and at least one of the partial plates is provided with a notch, and the partial plates are joined together to form the negative electrode tab. The square sealed battery according to claim 1, wherein a through-hole is formed.   The rectangular sealed battery according to claim 1 or 2, wherein an insertion stopper for setting an insertion position of the intermediate insulating polymer plate is provided on an inner wall of the battery outer can.   One or more protrusions are provided in a portion of the external negative electrode terminal that is in contact with the bent end of the negative electrode tab, and the protrusion and the bent end of the negative electrode tab have one point or multiple points. The rectangular sealed battery according to claim 1, wherein the rectangular sealed battery is in contact with each other.   The intermediate insulating polymer plate is made of any one of polyamide, polyimide, phenol resin, polyethylene terephthalate, polytetrafluoroethylene, tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer, polyvinylidene fluoride and polyvinyl fluoride. The square sealed battery according to any one of claims 1 to 4, wherein the battery is a square sealed battery.

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