JP2015011805A - Battery including wound electrode accommodated in rectangular parallelepiped case - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that, when a flat wall 12c and a flat wall 12e of a rectangular parallelepiped case 12 accommodating a wound electrode 10 are displaced to the inside thereof, a bottom plate 12f is swelled to the outside thereof to separate the bottom plate 12f from the wound electrode 10.SOLUTION: A recessed portion 12g displacing toward the inside side thereof is provided in a bottom plate 12f. When the recessed portion 12g is provided, even if a flat wall 12c and a flat wall 12e are displaced to the inside thereof, the bottom plate 12f is prevented from being swelled to the outside thereof, so that the bottom plate 12f is not separated from a wound electrode 10.

Description

  In the present specification, a battery in which a wound electrode is housed in a rectangular parallelepiped case is disclosed.

  Patent Document 1 discloses the battery described above. As shown in FIG. 1, this type of battery includes an insulating separator sheet 2, a positive electrode sheet 4 in which positive electrode active material layers 4 c and 4 d are coated on both surfaces of a metal foil 4 a, an insulating separator sheet 6, The negative electrode sheet 8 coated with the negative electrode active material layers 8c and 8d is overlapped on both surfaces of the metal foil 8a, and the wound sheet group is wound to form a wound electrode. Then, as shown in FIG. 2, the wound electrode 10 is accommodated in the rectangular parallelepiped case 12. The upper surface 12a of the rectangular parallelepiped case 12 is open, and after the wound electrode 10 is accommodated, it is closed using a lid or the like.

  The wound electrode 10 is wound around the winding shaft 10a, but has a flattened shape when observed from the direction along the winding shaft 10a, and has an upper curved portion 10b and a flat surface portion. 10c, the lower bending part 10d, and the plane part 10e.

  In the battery disclosed in this specification, the wound electrode 10 is accommodated in the rectangular parallelepiped case 12 with the winding shaft 10 a being parallel to the bottom plate 12 f of the rectangular parallelepiped case 12. The rectangular parallelepiped case 12 is formed in a shape that accommodates the wound electrode 10, and when accommodated, the flat surface portion 10 c of the wound electrode 10 faces the inner surface of the side wall 12 c of the rectangular parallelepiped case, and the flat surface of the wound electrode 10. The portion 10 e faces the inner surface of the side wall 12 e of the rectangular parallelepiped case, and the lower curved portion 10 d of the wound electrode 10 contacts the inner surface of the bottom plate 12 f of the rectangular parallelepiped case 10. Hereinafter, for simplification of terms, 12c and 12d are referred to as flat walls, and 12b and 12d are referred to as side walls.

  As shown in FIG. 1, the positive electrode sheet 4 is left with an uncoated part 4b where the positive electrode active material is not coated and the metal foil 4a is exposed. Similarly, the negative electrode sheet 8 is left with an uncoated portion 8b where the negative electrode active material is not coated and the metal foil 8a is exposed. When the sheets are overlapped, the uncoated portion 4 b is overlapped with the separator sheets 2 and 6, and the uncoated portion 8 b is overlapped with the positional relationship of protruding from the separator sheets 2 and 6. The uncoated part 4b and the uncoated part 8b protrude to the opposite side. In order to wind in that state, in the range 10g of FIG. 1, "separator sheet 2", "positive electrode active material layer 4c, positive electrode metal foil 4a, positive electrode active material layer 4d", "separator sheet 6" and "negative electrode" The active material layer 8c, the negative electrode metal foil 8a, and the negative electrode active material layer 8d ”are wound in a stacked state. In the range 10f, only the positive electrode metal foil 4a is wound, and in the range 10h, the negative electrode is used. Only the metal foil 8a is wound. In the range 10f, a positive electrode current collector (not shown) can be attached to the positive electrode metal foil 4a. In a range 10h, a negative electrode current collector (not shown) can be attached to the negative electrode metal foil 8a.

  As shown in Patent Document 1, an assembled battery may be formed by overlapping a plurality of batteries. In this case, a plurality of cases 12 are overlaid (stacked) on the outer surface of the flat wall 12e of the case 12 in such a positional relationship that the outer surfaces of the flat walls 12c of the adjacent cases 12 face each other. In an actual assembled battery, the assembled battery is compressed in the stacking direction with a spacer plate sandwiched between the flat wall 12e of the case 12 and the flat wall 12c of the adjacent case 12. A restraint band or the like is used to compress the assembled battery in the stacking direction. The spacer plate is smaller than the flat walls 12e and 12c, and the spacer plate is in close contact with a part of the flat walls 12e and 12c. When the restraint band strongly restrains, a part of the flat wall 12e of the case 12 and a part of the flat wall 12c of the adjacent case 12 are displaced to the inside of the case. Looking at individual cases, the distance between a part of the flat wall 12c and a part of the flat wall 12e approaches.

  Alternatively, a process for making the distance between the flat wall 12c and the flat wall 12e close may be performed in the manufacturing process of the unit cell. For example, the state shown in FIG. 3 may be changed to the state shown in FIG. When this deformation process is added, as is apparent from the comparison between FIG. 3 and FIG. 4, the planar portion 10 c of the wound electrode 10 is in close contact with the inner surface of the flat wall 12 c of the case 12, and the planar surface of the wound electrode 10. The portion 10e is firmly attached to the inner surface of the flat wall 12e of the case 12.

JP 2012-230837 A

  When the flat wall 12c and the flat wall 12e of the case 12 are deformed so that the distance between them approaches, the flat surface portion 10c of the wound electrode 10 is in close contact with the inner surface of the flat wall 12c of the case 12, and the flat surface portion 10e is flat wall. On the other hand, the bottom plate 12f of the case 12 is deformed so as to bulge outward as shown in FIG. As a result, the lower curved portion 10d of the wound electrode 10 is separated from the inner surface of the bottom plate 12f. If the lower curved portion 10d of the wound electrode 10 and the inner surface of the bottom plate 12f of the case 12 are separated from each other, the phenomenon that the wound electrode 10 vibrates in the case 12 becomes remarkable, and the reliability and durability of the battery are increased. Sex is reduced. The yield strength when an impact is applied to the case 12 is also reduced.

  In the present specification, even if the flat wall 12c and the flat wall 12e of the case 12 are deformed so that the distance between them approaches, the lower curved portion 10d of the wound electrode 10 and the inner surface of the bottom plate 12f of the case 12 are separated. Provide no technology.

In the battery disclosed in this specification, a wound electrode is housed in a rectangular parallelepiped case. The wound electrode is formed by winding up an overlapping sheet in which a positive electrode sheet, a separator sheet, and a negative electrode sheet are overlapped. The winding axis of the wound electrode is accommodated in a posture parallel to the bottom surface of the case.
In the battery disclosed in this specification, a recess that is displaced toward the inside of the case is formed in a part of the bottom plate of the case. The recess extends beyond the positive electrode active material coating range of the wound electrode. The edge of the wound electrode case on the bottom plate side is in contact with the inner surface of the recess.

  With the above configuration, when the flat walls of the case are deformed inward, the bottom plate of the case is suppressed from bulging outward. There is no separation between the lower curved portion of the wound electrode and the inner surface of the bottom plate of the case.

The figure which illustrates typically the overlapping sheet | seat which forms a wound type electrode. The figure which illustrates typically the relationship between a winding type electrode and a case. Sectional drawing of the conventional battery. The figure explaining the problem of the conventional battery. Sectional drawing of the battery disclosed by the specification. The figure which illustrates typically the problem of a prior art solved. The figure which looked at the battery disclosed by the specification from the flat wall side.

The main features of the embodiment are listed.
(Feature 1) A pair of restraining plates 14 and 14 are disposed outside the flat wall 12c and the flat wall 12e of the rectangular parallelepiped case 12, and the pair of restraining plates 14 and 14 are brought close to each other to bring the flat wall 12c and the flat wall 12e closer. .
(Characteristic 2) A pair of restraint plates 14 and 14 are brought close to each other in a positional relationship in which a space remains between the bottom plate 12f of the rectangular parallelepiped case 12 and the restraint plates 14 and 14.
(Characteristic 3) A battery pack is formed by stacking a plurality of rectangular parallelepiped cases and compressing them in the stacking direction. In that case, the flat wall 12c and the flat wall 12e of the rectangular parallelepiped case 12 are made to approach.
(Feature 4) The wound electrode 10 is fixed to a lid that covers the open upper surface of the rectangular parallelepiped case 12.
(Feature 5) The negative electrode active material coating range is wider than the positive electrode active material coating range. In the positive electrode active material coating range, “separator sheet”, “positive electrode active material layer, positive electrode metal foil and positive electrode active material layer”, “separator sheet”, “negative electrode active material layer, negative electrode metal foil and negative electrode active material layer” "All members are struck in a stacked state." In other areas, some members are wound in a missing state. In the positive electrode active material coating range in which all members are wound in a laminated state, the wound electrode is densely wound and the strength of the wound electrode is high. When the positive electrode active material coating range is supported, the wound electrode is positioned.

The wound electrode 10 and the overlapping sheet that forms the wound electrode 10 are as described with reference to FIGS. 1 and 2 and will not be described repeatedly. In this example, the negative electrode active material coating range is slightly wider than the positive electrode active material coating range. In the positive electrode active material coating range, “separator sheet 2”, “positive electrode active material layer 4c, positive electrode metal foil 4a, positive electrode active material layer 4d”, “separator sheet 6”, “negative electrode active material layer 8c, and negative electrode metal” The foil 8a and the negative electrode active material layer 8d ”are all rolled up in a state of being laminated.
In the rectangular parallelepiped case 12 of the present embodiment, as shown in FIGS. 5 to 7, a portion that is displaced toward the inside of the case 12 is formed in a part of the bottom plate 12 f. When observed from the outside of the case 12, a recess 12g is formed in a part of the bottom plate 12f of the case 12.
As shown in FIG. 5, the width and position of the recess 12 g are formed so as to be in contact with the vicinity of the lower end edge of the lower curved portion 10 d of the wound electrode 10. As shown in FIG. 7, the length and position of the recess 12g are formed at a length and position extending beyond the range 10g where the positive electrode active material is applied. In FIG. 7, for the sake of clarity, the lower curved portion 10d of the wound electrode 10 and the recess 12g are illustrated as being separated from each other. The vicinity is in contact with the inner surface of the recess 12g.

  In the range 10f, only the positive electrode metal foil 4a is wound, and a positive electrode current collector (not shown) is connected to the positive electrode metal foil 4a. The positive electrode current collector is connected to the positive electrode bolt 16. In the range 10h, only the negative electrode metal foil 8a is wound, and a negative electrode current collector (not shown) is connected to the negative electrode metal foil 8a. The negative electrode current collector is connected to the negative electrode bolt 18. The positive electrode current collector and the positive electrode bolt 16 and the negative electrode current collector and the negative electrode bolt 18 pass through a lid that covers the opened upper surface of the rectangular parallelepiped case. The positive electrode current collector and the positive electrode bolt 16 and the negative electrode current collector and the negative electrode bolt 18 are insulated from the lid. The wound electrode 10 is positioned with respect to the lid by the positive electrode current collector and the positive electrode bolt 16 and the negative electrode current collector and the negative electrode bolt 18.

At the time of manufacture, the wound electrode 10 is positioned with respect to the lid by the positive electrode current collector and the positive electrode bolt 16 and the negative electrode current collector and the negative electrode bolt 18, and the wound electrode 10 is inserted into the case 12 in this state. The open upper surface of the rectangular parallelepiped case 12 is closed with a lid, and the case 12 and the lid are fixed.
Then, as shown in FIG. 6, a pair of restraining plates 14 and 14 are disposed outside the flat wall 12c and the flat wall 12e of the rectangular parallelepiped case 12, and the pair of restraining plates 14 and 14 are brought close to the flat wall 12c. The flat wall 12e is brought closer.
At this time, if the bottom plate 12f of the case 12 is flat, as shown in FIG. 4, the bottom plate 12f bulges outward as the flat wall 12c and the flat wall 12e are displaced inward. On the other hand, when the recess 12g is formed in the bottom plate 12f of the case 12, as shown in FIG. 6, the bottom plate 12f bulges outward even when the flat wall 12c and the flat wall 12e are displaced inward. Can be prevented. According to the present embodiment, the flat wall 12c of the case 12 is displaced inward, the flat portion 10c of the wound electrode 10 is in close contact with the inner surface of the flat wall 12c of the case 12, and the flat wall 12e of the case 12 is inward. Displacement causes the flat portion 10e of the wound electrode 10 to be in close contact with the inner surface of the flat wall 12e of the case 12, and the lower curved portion 10d of the wound electrode 10 and the inner surface of the bottom plate 12f are kept in close contact. .
According to the present embodiment, the flat portion 10 c, the flat portion 10 e, and the lower curved portion 10 d of the wound electrode 10 are in close contact with the inner surface of the case 12. Moreover, since the recess 12g extends beyond the positive electrode active material coating range 10g, the portion of the wound electrode 10 that is tightly wound up with no gap between the sheets is full length. It is restrained by the recess 12g. As a result, the wound electrode 10 is difficult to vibrate relative to the case 12 in the case 12. Improves battery reliability and durability.

  In the above, the flat wall 12c and the flat wall 12e are displaced inward in the manufacturing process of the unit cell. The usefulness of the present embodiment is not limited thereto. It is also useful when a plurality of single cells are stacked and the flat wall 12c and the flat wall 12e are displaced inward by strongly compressing or restraining in the stacking direction.

  The effect of preventing the bulging deformation of the bottom plate 12f by the recess 12g varies depending on the depth of the recess 12g and the like. By experimentation, the depth of the recess 12g necessary to prohibit the bulging deformation of the bottom plate 12f can be determined.

  In addition, providing the recess in the bottom plate of the rectangular parallelepiped case is known per se, and is described in, for example, Japanese Patent Application Laid-Open Nos. 2013-77495 and 2004-71224. In the technique disclosed in Japanese Patent Laid-Open No. 2013-77495, the winding shaft of the wound electrode is accommodated in a posture perpendicular to the bottom plate. Then, the range where only the positive electrode metal foil not coated with the positive electrode active material is wound faces the bottom plate. The positive electrode metal foil is wound into an oval shape having a space at the center. If the bottom plate is provided with an oval-shaped recess (projection when viewed from the wound electrode side), it is possible to ensure conduction by entering the inside of the metal foil for the positive electrode where the projection is wound. It becomes. Providing a recess in the bottom plate is for ensuring conduction, and does not correspond to deformation of the case. It does not suggest a technique corresponding to the deformation of the case by providing a recess in the bottom plate. In the technique disclosed in Japanese Patent Application Laid-Open No. 2004-71224, a recess is provided on the bottom surface of the case in order to cope with a phenomenon in which the positive electrode lattice extends during overcharge. It does not correspond to the deformation of the case, and does not suggest a technique corresponding to the deformation of the case by providing a recess in the bottom plate.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Separate sheet 4: Positive electrode sheet 6: Separate sheet 8: Negative electrode sheet 10: Winding type electrode 10g: Positive electrode active material coating range 12: Case 12f: Bottom plate 12g: Recess

Claims (1)

In a rectangular parallelepiped case, a wound electrode formed by winding up a superposed sheet of a positive electrode sheet, a separator sheet, and a negative electrode sheet is housed in a posture in which the winding axis is parallel to the bottom plate of the case. ,
A recess that is displaced toward the inside of the case is formed in a part of the bottom plate of the case,
The recess extends beyond the positive electrode active material coating range of the wound electrode,
The inner edge of the recess is in contact with the edge of the wound electrode case on the bottom plate side,
A battery characterized by that.

Images