JP2019186068A - Sealed battery - Google Patents

Abstract

To provide a sealed battery in which foreign matter is less likely to enter a gap between a flat portion of a wound electrode body and a case.SOLUTION: A sealed battery 10 includes: a case body 21; a lid 22; and a wound electrode body 30. The electrode body 30 includes a pair of flat surfaces 30a and a pair of curved portions 30b configured around a winding axis Ax. The pair of flat surfaces 30a are opposed to a pair of wide surfaces 21a. Of the pair of curved portions 30b, one curved portion 30b1 is accommodated in the case body 21 so as to be directed to the lid 22. In the curved portion 30b1 directed to the lid 22, a double-sided tape 35 is stuck over the entire width along a winding axis Ax of an outermost separator.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a sealed battery.

  Japanese Patent Laying-Open No. 2015-002147 discloses a method for manufacturing a sealed battery in which a positive electrode side end surface of a lid is brought into contact with an opening of a battery can, and then a negative electrode side portion of the lid is inserted into the opening. Yes. According to such a method for manufacturing a sealed battery, even if a foreign object is generated when the lid is inserted into the opening, it is generated on the negative electrode terminal side, so that the voltage drop of the sealed battery is unlikely to occur. .

  Japanese Patent Laid-Open No. 2012-186005 discloses a battery in which an insulating sheet member interposed between an electrode body and a battery case to insulate the two is provided with an extending portion extending toward the sealing lid. . In the battery, the extending portion of the insulating sheet member is interposed between the opening of the battery case and the peripheral portion of the sealing lid, and is configured to prevent foreign matter from entering from the portion where the extending portion is interposed. ing.

  Furthermore, Japanese Patent Laying-Open No. 2015-056357 discloses a power storage device that includes a partition member that covers the liquid injection hole from the electrode assembly side. According to such a power storage device, even if foreign matter is mixed into the case from the liquid injection hole, the foreign matter is stored in the storage space partitioned by the partition member.

Japanese Patent Laying-Open No. 2015-002147 JP 2012-186005 A Japanese Patent Laying-Open No. 2015-056357

  Spatter generated when the battery case is sealed by welding may enter the battery case through the liquid injection hole. In this case, in particular, it is desired to prevent foreign matter from entering the gap between the flat portion of the wound electrode body to which the restraining pressure acts and the case.

The sealed battery disclosed herein has a pair of opposed wide surfaces, a substantially rectangular parallelepiped case main body opened on the other side surface, and welded to the case main body in a state of being attached to the opening of the case main body. And an electrode body in which a belt-like first separator, a belt-like positive electrode sheet, a belt-like second separator, and a belt-like negative electrode sheet are wound in such a manner that their length directions are aligned in order. The electrode body is wound around a winding axis set in the width direction orthogonal to the length direction so that one of the first separator and the second separator is the outermost periphery.
The electrode body has a pair of flat surfaces formed around the winding axis, and a pair of curved portions provided between the pair of flat surfaces. Further, the pair of flat surfaces are accommodated in the case body such that the pair of flat surfaces face the pair of wide surfaces of the case body, and one of the pair of curved portions faces the lid. A double-sided tape is attached to the curved portion directed to the lid over the entire width of the outermost separator along the winding axis.

  According to such a sealed battery, since the foreign matter is captured by the double-sided tape, the foreign matter is unlikely to enter the gap between the battery case and the flat portion of the wound electrode body.

FIG. 1 is a partial cross-sectional view of a sealed battery 10. FIG. 2 is a vertical side view of the sealed battery 10.

  Hereinafter, an embodiment of a sealed battery will be described. It should be noted that the embodiments described herein are not intended to limit the present invention. Each figure is a schematic diagram and does not necessarily reflect the actual product faithfully. Here, front, back, top, bottom, left, and right are represented by F, Rr, U, D, L, and R, respectively, in the figure. However, front, rear, upper, lower, left, and right are only directions for convenience of explanation, and do not limit the installation mode of the sealed battery 10 or the like.

  FIG. 1 is a partial cross-sectional view of a sealed battery 10. FIG. 1 illustrates a state in which one wide surface of the battery case is broken and the electrode body accommodated in the battery case is exposed. FIG. 2 is a vertical side view of the sealed battery 10. As shown in FIGS. 1 and 2, the sealed battery 10 includes a battery case 20 and an electrode body 30. The battery case 20 accommodates the electrode body 30. Further, the battery case 20 contains an electrolytic solution.

The battery case 20 includes a case body 21 and a lid 22. The battery case 20 is made of, for example, aluminum or an aluminum alloy.
As shown in FIG. 2, the case main body 21 has a pair of opposing wide surfaces 21a, and the other one side surface is open. The case body 21 is a substantially rectangular parallelepiped case. In this embodiment, the other opened side surface is the upper surface of the case body 21. The upper surface of the case body 21 constitutes an opening 21b.

  The wide surface 21a has a rectangular shape that is long in one direction. Here, the wide surface 21a is long in the horizontal direction in FIG. 1 and short in the vertical direction. A narrow surface 21c is connected to the short side of the wide surface 21a extending in the vertical direction. The narrow surface 21c also has a rectangular shape that is long in one direction. In the case body 21, the opening 21b is provided on a side surface (here, the upper surface) connected to the long side of the wide surface 21a and the short side of the narrow surface 21c.

  The lid 22 is welded to the case body 21 in a state where the lid 22 is attached to the opening 21 b of the case body 21. The lid | cover 22 is a plate-shaped member according to the shape of the opening 21b. The lid 22 is attached to the opening 21b so as to cover the opening 21b of the case main body 21, and the peripheral edge portion 22a of the lid 22 is welded to the edge of the opening 21b.

  The lid 22 includes a liquid injection hole 22b. The liquid injection hole 22b is a hole that penetrates the lid 22 in the vertical direction. The liquid injection hole 22b is a hole for injecting an electrolytic solution. However, in the completed sealed battery 10, the liquid injection hole 22b is sealed by the sealing member 22c. Current collecting terminals 41 are respectively attached to both sides of the lid 22.

  The electrode body 30 is configured by a strip-shaped first separator 31, a strip-shaped positive electrode sheet 32, a strip-shaped second separator 33, and a strip-shaped negative electrode sheet 34 that are stacked in order in the length direction. The electrode body 30 is wound so that one of the first separator 31 and the second separator 33 is the outermost periphery. Specifically, the belt-shaped first separator 31, the positive electrode sheet 32, the second separator 33, and the negative electrode sheet 34 are wound around a winding axis Ax set in the width direction orthogonal to the length direction. In this embodiment, the electrode body 30 is wound so that the second separator 33 is on the outermost periphery.

  The first separator 31 and the second separator 33 are made of, for example, a porous resin sheet having required heat resistance and allowing the electrolyte to pass therethrough. Various materials for the separator have been proposed and are not particularly limited.

  The positive electrode sheet 32 has a positive electrode active material layer containing a positive electrode active material formed on both sides of a strip-shaped metal foil (for example, an aluminum foil; hereinafter referred to as a positive electrode current collector foil) having a predetermined width and thickness. It is a member. However, the non-formed part 32a in which the positive electrode active material layer is not formed is set with a constant width at one end in the width direction. For example, in a lithium ion secondary battery, the positive electrode active material is a material capable of releasing lithium ions during charging and absorbing lithium ions during discharging, such as a lithium transition metal composite material. Various positive electrode active materials are generally proposed besides lithium transition metal composite materials, and are not particularly limited.

  The negative electrode sheet 34 is a member in which a negative electrode active material layer containing a negative electrode active material is formed on both surfaces of a metal foil (for example, copper foil; hereinafter referred to as a negative electrode current collector foil) having a predetermined width and thickness. It is. However, the non-formed part 34a in which the negative electrode active material layer is not formed is set with a constant width at one end in the width direction. For example, in the case of a lithium ion secondary battery, the negative electrode active material is a material that can occlude lithium ions during charging and release lithium ions occluded during charging, such as natural graphite. Various negative electrode active materials are generally proposed besides natural graphite, and are not particularly limited.

  As shown in FIG. 2, the electrode body 30 has a pair of flat surfaces 30a formed around the winding axis Ax, and a pair of curved portions 30b provided between the pair of flat surfaces 30a. Yes. The curved portion 30b is also called an R portion.

  The electrode body 30 has a pair of flat surfaces 30 a facing the pair of wide surfaces 21 a of the case main body 21, and one curved portion 30 b 1 of the pair of curved portions 30 b is directed to the lid 22. Contained. A constant gap is provided between the lid 22 and the curved portion 30b1 (hereinafter referred to as the first curved portion 30b1) facing the lid 22 of the pair of curved portions 30b. The electrode body 30 is accommodated in the case body 21 in a state of being covered with, for example, an insulating film (not shown).

  As shown in FIG. 1, the double-sided tape 35 is stuck to the 1st curved part 30b1 over the full width along the winding axis Ax of the separator 33 of the outermost periphery. As shown in FIG. 2, here, the double-sided tape 35 is affixed with a required width along the curvature of the first curved portion 30b1 from the front side to the rear side of the first curved portion 30b1. The double-sided tape 35 is attached, for example, so that the end portion (lower end portion) on the flat surface 30a side reaches the vicinity of the boundary portion (the portion where the bending starts) between the first curved portion 30b1 and the flat surface 30a. Good.

  In this embodiment, the double-sided tape 35 also serves as a winding tape that fixes the outermost peripheral end portion 33a of the outermost peripheral separator (here, the second separator 33). In other words, the winding tape attached to the outermost peripheral end portion 33 a of the outermost peripheral separator 33 is disposed on the first curved portion 30 b 1 facing the lid 22 among the pair of curved portions 30 b of the electrode body 30. Double-sided tape is used.

  One current collecting terminal 41 is welded to each of the non-formed part 32 a of the positive electrode sheet 32 and the non-formed part 34 a of the negative electrode sheet 34. The current collecting terminal 41 is attached to the lid 22 with an insulating member such as a gasket interposed therebetween. External terminals 42 and bolt terminals 43 are disposed outside the lid 22 with an insulating member such as an insulator interposed therebetween. A part of the current collecting terminal 41 passes through the lid 22 through the electrode hole, and is electrically connected to the external terminal 42 and the bolt terminal 43 outside the lid 22.

  In the production of the sealed battery 10, the belt-like first separator 31, the positive electrode sheet 32, the second separator 33, and the negative electrode sheet 34 are wound as described above, and a flat electrode body 30 is prepared. The current collecting terminal 41, the external terminal 42, and the bolt terminal 43 are assembled to the lid 22, and the electrode body 30 is attached to the current collecting terminal 41. Next, the lid 22 is attached to the opening 21 b of the case body 21 while the electrode body 30 assembled to the lid 22 is inserted into the case body 21. And the lid | cover 22 is welded to the case main body 21 over a perimeter. After the lid 22 is welded, the electrolytic solution is injected from the liquid injection hole 22b. Thereafter, the battery case 20 is sealed by welding the sealing member 22c to the liquid injection hole 22b.

  Spatter generated when the lid 22 is welded to the opening 21b of the case body 21 may enter the case body 21 from the liquid injection hole 22b or the like. Even when spatter enters the case main body 21, it is particularly desirable to prevent foreign matter from entering the gap between the flat surface 30 a of the electrode body 30 to which the restraining pressure acts and the case main body 21.

  In the sealed battery 10, a double-sided tape 35 is affixed to the first curved portion 30 b 1 of the electrode body 30. The double-sided tape 35 is affixed over the entire width along the winding axis Ax of the outermost separator 33. Therefore, the adhesive surface 35 a of the double-sided tape 35 is directed to the lid 22 over the entire width along the winding axis Ax of the outermost peripheral separator 33. The double-sided tape 35 supplements foreign matter that has entered from the liquid injection hole 22 b of the lid 22. For this reason, it is difficult for foreign matter to enter the gap between the wide surface 21 a of the case body 21 and the flat surface 30 a of the electrode body 30. In particular, since a large foreign substance is easily captured by the double-sided tape 35, it is difficult to enter a gap between the wide surface 21 a of the case body 21 and the flat surface 30 a of the electrode body 30.

  In addition, in terms of preventing foreign matter from entering the gap between the wide surface 21a of the case body 21 and the flat surface 30a of the electrode body 30, the double-sided tape 35 attached to the first curved portion 30b1 is a wide surface of the case body 21. It is good to extend to the vicinity of 21a. In this embodiment, the double-sided tape 35 is affixed so that it may reach the back side from the front side of the 1st curved part 30b1. For this reason, it is difficult for foreign matter to enter the gap on either the front side or the rear side.

  In addition, the double-sided tape 35 affixed on the 1st curved part 30b1 is not limited to this structure, The double-sided tape 35 may be affixed on the front side and the back side of the 1st curved part 30b1, respectively. In this embodiment, the double-sided tape 35 also serves as a winding stop tape that fixes the outermost peripheral end portion 33 a of the outermost peripheral separator 33. However, for example, from the viewpoint of preventing foreign matter from entering a gap between the wide surface 21 a of the case body 21 and the flat surface 30 a of the electrode body 30, the double-sided tape 35 has the outermost peripheral end portion 33 a of the outermost separator 33. It does not have to serve as a winding tape for fixing the.

  Moreover, in this embodiment, the double-sided tape 35 is stuck so as not to hang on the pair of flat surfaces 30a of the electrode body 30 while hanging on the first bending portion 30b1. According to such a configuration, even when the lid assembly in which the electrode body 30 and the like are assembled to the lid 22 is assembled to the case body 21, the adhesive surface 35 a does not stick to the inner wall of the wide surface 21 a of the case body 21. Therefore, the lid assembly can be assembled to the case body 21 without reducing productivity.

  The adhesive surface 35a directed to the lid 22 of the double-sided tape may have a stronger adhesive force than the adhesive surface bonded to the first curved portion 30b1. The adhesive surface that is affixed to the first curved portion 30b1 is merely an adhesive force that allows the double-sided tape 35 to be fixed to the first curved portion 30b1, or only the outermost peripheral end portion 33a is fixed to the first curved portion 30b1. If it has the adhesive strength of, it is enough. However, it is desirable that the adhesive surface 35a directed to the lid 22 has a stronger adhesive force in order to keep the captured foreign matter thereafter. According to such a configuration, foreign matter in the gap between the wide surface 21a of the case body 21 and the flat surface 30a of the electrode body 30 can be captured more reliably.

  Heretofore, various types of sealed batteries proposed here have been described. Unless otherwise stated, the embodiments of the sealed battery and the like listed here do not limit the present invention.

DESCRIPTION OF SYMBOLS 10 Sealed battery 20 Battery case 21 Case main body 21a Wide surface 21b Opening 21c Narrow surface 22 Lid 22a Peripheral part 22b Injection hole 22c Sealing member 30 Electrode body 30a Flat surface 30b Curved part 30b1 First curved part 31 First separator 32 Positive electrode sheet 32a Unformed portion 33 Second separator (outermost separator)
33a Outermost peripheral edge 34 Negative electrode sheet 34a Unformed part 35 Double-sided tape 35a Adhesive surface 41 facing the lid 41 Current collecting terminal 42 External terminal 43 Bolt terminal Ax Winding shaft

Claims (1)

A case body having a substantially rectangular parallelepiped shape having a pair of opposed wide surfaces and the other one side surface opened;
A lid welded to the case body in a state of being attached to the opening of the case body;
A strip-shaped first separator, a strip-shaped positive electrode sheet, a strip-shaped second separator, and a strip-shaped negative electrode sheet are stacked in order in the length direction, and one of the first separator and the second separator is the outermost periphery. An electrode body wound around a winding axis set in a width direction orthogonal to the length direction so as to become,
The electrode body is
A pair of flat surfaces configured around the winding axis, and a pair of curved portions provided between the pair of flat surfaces;
The pair of flat surfaces are opposed to the pair of wide surfaces of the case main body, and one of the pair of curved portions is accommodated in the case main body so as to face the lid,
In the curved portion directed to the lid, a double-sided tape is affixed over the entire width of the outermost separator along the winding axis,
Sealed battery.

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