JP2014107069A - Vehicular secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid entry of a collector into an electrode bundle by suppressing deformation of the collector even if a case member receives impact from the outside, in a vehicular secondary battery.SOLUTION: A secondary battery includes: a flat electrode bundle 20 in which a laminate 25 formed by offsetting and laminating a positive electrode plate 21 and a negative electrode plate 22 through a separator 23 is wound; collectors 31, 32 united to the exposed portions 21B, 22B of the positive electrode plate 21 or the negative electrode plate 22 at the end fringe parts of the electrode bundle 20; a pair of front parts 13, 13 housing the electrode bundle 20 and the collectors 31, 32 and facing the flat face of the electrode bundle 20; a pair of end face parts 14, 14 positioned at both ends of a pair of the front parts 13, 13; and a rectangular prism-shaped case member 11 including a top face part 12 and a lower face part 15. The collectors 31, 32 extend along the exposed portion, and a rigidity reinforcing cross-sectional deformation part 16 extending in a direction perpendicular to the end face part 14 is formed in the front part 13 correspondingly to the region where the collectors 31, 32 extend.

Description

  The present invention relates to a vehicular secondary battery mounted on a vehicle such as an automobile.

  Conventionally, for example, a sealed secondary battery such as a nickel-hydrogen secondary battery or a non-aqueous electrolyte secondary battery represented by a lithium ion secondary battery as a secondary battery for a relatively small electronic device such as a mobile phone or a personal computer. Secondary batteries are known. In recent years, such a sealed secondary battery has been developed as a large-scale and large-capacity power source mounted on various electric vehicles such as electric vehicles, hybrid vehicles, and electric motorcycles.

As the structure of such a sealed secondary battery, for example, a flat electrode group in which a belt-like positive electrode plate and a negative electrode plate are both stacked in a flat shape via a belt-like separator ( Some electrode bundles) are housed in a rectangular exterior member (cell case) together with a non-aqueous electrolyte, and the exterior member has an upper opening sealed by a lid member (see, for example, Patent Document 1).
The positive electrode plate is assembled at one end of the electrode bundle in the axial direction, the negative electrode plate is assembled at the other axial end of the electrode bundle, and is connected to one end side of the current collector, and the other end side of the current collector is It is connected to a terminal portion provided on the lid member. For example, in the configuration described in Patent Document 1, the positive electrode plate and the negative electrode plate are connected to the positive electrode terminal and the negative electrode terminal corresponding to the terminal portion by the positive electrode lead and the negative electrode lead corresponding to the current collector.

  The positive electrode lead and the negative electrode lead have a connection plate connected to the terminal portion and a strip-shaped current collector (lead portion) extending downward from the connection plate, and the current collector is a positive electrode plate or Connected to the negative electrode plate. The current collector extends downward from the connection plate so as to be substantially parallel to the surface of the electrode bundle. In the configuration described in Patent Document 1, the strip-shaped current collector is extended from a connection plate (connection portion) so as to be substantially parallel to the surface of the flat electrode bundle.

JP 2011-71109 A

  By the way, when such a secondary battery is mounted on a vehicle, not only electrical characteristics such as battery charge / discharge characteristics and life characteristics, but also a short circuit is required not to occur even in the event of an accident. . In the case of a vehicle secondary battery, a large number of batteries are stored in a battery case, for example, as a module, and the battery case is attached to the vehicle body. The battery case includes a horizontally disposed tray and a cover that is mounted so as to cover the upper side of the tray. Many batteries have their terminals facing upward on the tray, and the front and rear sides and the side of the vehicle. Arranged side by side.

  The battery case and the cell case are required to have a structure capable of protecting the internal battery even in the event of an accident, but it is difficult to avoid the deformation of the cell case depending on the degree and form of the collision. If the cell case is deformed, an internal short circuit may occur due to this. In particular, when an external force is applied near the terminal near the end of the top surface of the cell case, the cell case is buckled and the current collector is deformed inward and enters the electrode bundle. Therefore, there is a possibility that an internal short circuit may occur due to contact with the positive electrode plate or the negative electrode plate.

  The present invention has been devised in view of such problems, and even when the exterior member (cell case) receives an external impact, the deformation of the current collector is suppressed and the current collector can enter the electrode bundle. An object of the present invention is to provide a vehicular secondary battery that can be avoided.

  In order to achieve the above object, a secondary battery for a vehicle according to the present invention is a flat battery in which a laminated body in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween is wound around a winding axis. The positive electrode plate or the negative electrode plate is exposed from the overlapping part of the laminate and is coupled to the exposed part formed along the edge part in the electrode bundle formed in a shape and the edge part of the electrode bundle. A current collector, a pair of front portions that house the electrode bundle and the current collector and face the flat surface of the electrode bundle, a pair of end surface portions located at both ends of the pair of front portions, and an upper surface A secondary battery for a vehicle, comprising: an exterior member that is formed in a rectangular parallelepiped shape, and the current collector is adjacent to any one of the end surface portions, the current collector comprising: It extends along the exposed part, and extends in the direction intersecting the end face part on the front part. Formed sexual reinforcing cross deformable portion, the rigid reinforcing sectional deformation portion is characterized in that it is formed to correspond to the region of extension of the current collector.

  The phrase “formed corresponding to the region where the current collector extends” does not necessarily mean that the current collector is disposed so as to include the entire region where the current collector extends. Any region can be used as long as the region in which the electric body extends can be strengthened more rigidly than the other regions. For example, the region where the rigidity-enhancing cross-section deformed portion is formed is close to the boundary of the region where the current collector extends, but may be arranged in a range not including this boundary.

It is preferable that the rigidity-enhancing cross-sectional deformation portion is formed to extend from a central portion of the front portion to a portion close to the end surface portion.
It is preferable that the rigidity-enhancing cross-sectional deformation portion extends in a region corresponding to the overlapping portion of the laminate.
Note that the “region corresponding to the overlapping portion of the stacked body” does not necessarily include the entire region where the overlapping portion of the stacked body exists. Here, there is an exposed portion where the positive electrode plate or the negative electrode plate is exposed from the overlapping portion of the laminated body at the edge portion of the electrode bundle, and the current collector in which the cross-section deforming portion for reinforcing rigidity is disposed in the exposed portion Since it is desirable to avoid interference, it means that it is preferable that the cross-sectional deformation portion for reinforcing rigidity avoids the region where the exposed portion exists and forms the cross-sectional deformation portion for reinforcing rigidity as close to the end surface as possible. .

It is preferable that the rigidity-enhancing cross-sectional deformation part is formed in a curved surface shape.
The curved surface in this case is preferably a curved surface that is curved around an axis parallel to the winding axis, has a concave shape on the outer surface side of the exterior member and a convex shape on the inner surface side of the exterior member, for example, a partial cylindrical shape. However, the cross-sectional deformation portion for reinforcing rigidity is not limited to this, and the outer surface side of the exterior member may be concave and the inner surface side of the exterior member may be a convex bent surface (a concave or convex surface constituted by a plurality of planes). For example, a shape in which only the inner surface side of the exterior member is thick may be used.

It is preferable that the current collector is disposed with an upper end connected to a positive electrode terminal or a negative electrode terminal provided at an end of the upper surface, and a lower end extending to the vicinity of the lower end of the exposed portion.
As the current collector, a positive electrode current collector coupled to a positive electrode exposed portion formed by exposing the positive electrode plate to one end edge side of the electrode bundle, and the negative electrode plate exposed to the other end edge side of the electrode bundle. It is preferable that the positive electrode current collector and the negative electrode current collector are adjacent to the corresponding end surface portions, respectively.

  According to the present invention, in the exterior member, for example, when the end surface portion receives an external force that causes buckling deformation from the upper surface portion, the rigidity of the front surface portion adjacent to the end surface portion opposes this external force and the end surface portion It acts to prevent buckling deformation. The current collector extends along the edge and the exposed portion of the electrode bundle, and the front surface portion has a cross-sectional deformation portion for reinforcing rigidity extending in a direction intersecting the end surface portion. Therefore, in the region where the current collector extends, the effect of preventing buckling deformation of the end surface portion by the cross section deforming portion for strengthening the rigidity is strong. For this reason, even if buckling deformation of the end face portion occurs, it occurs outside the region where the current collector extends. Therefore, even if the end face portion is buckled and deformed, the current collector is hardly deformed, and the current collector is deformed inward and enters the electrode bundle and may contact the positive electrode plate or the negative electrode plate to cause an internal short circuit. It can be avoided.

It is a perspective view of the secondary battery for vehicles concerning a 1st embodiment of the present invention. It is a disassembled perspective view of the secondary battery for vehicles concerning a 1st embodiment of the present invention. It is a longitudinal cross-sectional view of the secondary battery for vehicles concerning 1st Embodiment of this invention. It is a horizontal sectional view of the secondary battery for vehicles concerning a 1st embodiment of the present invention, and Drawing 4 (a) is an AA arrow sectional view of Drawing 3, and Drawing 4 (b) is B of Drawing 3. It is -B arrow sectional drawing. It is a figure explaining the laminated structure of the positive electrode plate of the vehicle secondary battery concerning each embodiment of this invention, a negative electrode plate, and a separator. It is a disassembled perspective view of the vehicle-mounted case which modularizes and mounts the vehicle secondary battery concerning each embodiment of this invention in a vehicle. It is a disassembled perspective view of the battery module which accommodates the secondary battery for vehicles concerning each embodiment of the present invention, (a) shows the 1st example and (b) shows the 2nd example. It is a perspective view of the vehicle explaining the mounting state to the vehicle of the vehicle-mounted case of the vehicle secondary battery according to each embodiment of the present invention. It is a figure explaining the effect by the secondary battery for vehicles concerning each embodiment of the present invention, (a) is a longitudinal section of the secondary battery for vehicles which shows the buckling situation of the conventional exterior member, (b FIG. 4 is a longitudinal sectional view of a vehicular secondary battery showing a buckling state of an exterior member according to each embodiment. It is a perspective view of the secondary battery for vehicles concerning a 2nd embodiment of the present invention. It is a figure which shows the secondary battery for vehicles concerning 3rd Embodiment of this invention, (a) is the perspective view, (b) is the longitudinal cross-sectional view [CC arrow directional cross-sectional view of Fig.11 (a)] ].

Hereinafter, embodiments will be described with reference to the drawings. Note that the embodiment described below is merely an example, and there is no intention to exclude various modifications and technical applications that are not explicitly described in the following embodiment. Each configuration of the following embodiments can be implemented with various modifications without departing from the spirit thereof, and can be selected as necessary or can be appropriately combined.
In addition, although the secondary battery for vehicles concerning each embodiment illustrates what is applied to a motor vehicle, application to vehicles other than a motor vehicle is effective for this secondary battery for vehicles.

[1. First Embodiment]
[1-1. overall structure]
The vehicle secondary battery according to the first embodiment will be described with reference to FIGS. In the following description, the vertical direction or the vertical direction means the vertical direction or the substantially vertical direction. Further, the horizontal direction indicates a vertical direction or a direction orthogonal to the substantially vertical direction.

First, the overall structure of the secondary battery 1 to which the present electrode structure is applied will be described. In this embodiment, a lithium ion secondary battery is illustrated as the secondary battery 1.
As shown in FIGS. 1 and 2, the secondary battery 1 according to this embodiment is a sealed secondary battery, and includes an electrode bundle (element) 20 including a positive electrode plate 21 and a negative electrode plate 22, A positive electrode current collector (positive electrode lead) 31 and a negative electrode current collector (negative electrode lead) 32 are housed and configured in a cell case 10 as an exterior member together with a non-aqueous electrolyte (not shown). Although details will be described later, the electrode bundle 20 is formed in a flat shape, and the cell case 10 is formed in a square shape corresponding to the shape of the electrode bundle 20, that is, a rectangular parallelepiped shape.

  The cell case 10 includes a bottomed rectangular tube-shaped cell case main body 11 having an open top, and a lid member 12 mounted on the open top of the cell case main body 11. Is done. The cell case main body 11 and the lid member 12 are made of, for example, a metal such as an aluminum alloy, iron, or stainless steel, and the lid member 12 is firmly fixed to the cell case main body 11 by welding or the like.

In addition, in the cell case 10, although illustration is abbreviate | omitted, the insulating member which covers the inner surface of the cell case 10 is equipped. Thereby, the cell case 10 is insulated from the electrode bundle 20 and current collectors 31 and 32 accommodated therein and the electrolyte solution (not shown).
As shown in FIGS. 1 to 4, the cell case body 11 includes a pair of front portions 13 and 13 that are opposed to and parallel to both flat surfaces of the flat electrode bundle 20, and the pair of front portions 13 and 13. 13 is provided with a pair of end face portions 14 and 14 which are located at both ends of the base plate 13 and parallel to each other, and a bottom face portion 15, and an upper portion is open. In the upper opening of the cell case main body 11, a lid member 12 is arranged and attached in parallel with the bottom surface portion 15. Therefore, the cell case 10 is formed in a rectangular parallelepiped shape including six surfaces including the front surface portions 13 and 13 and the end surface portions 14 and 14, the lid member (upper surface portion) 12, and the bottom surface portion (lower surface portion) 15.

  As shown in FIG. 5, the electrode bundle 20 includes a strip-like positive electrode plate 21 and a negative electrode plate 22 that extend in the vertical direction in the drawing, with separators 23 and 24 sandwiched therebetween, and one end portion of the positive electrode plate 21 is The other end of the negative electrode plate 22 is offset from the other end of each of the positive electrode plate 21 and the separators 23, 24 so as to protrude outward (to the left in FIG. 5) from one end of the negative electrode plate 22 and the separator 23. The laminated body 25 laminated in an offset state so as to protrude outward (rightward in FIG. 5) is wound around an axis along the width direction (hereinafter, this axis is referred to as a winding axis). By being turned, it is formed in a flat shape as shown in FIG.

  The positive electrode plate 21 has a positive electrode active material layer portion 21A in which a positive electrode active material such as lithium manganate is applied to both surfaces of a substrate made of, for example, an aluminum foil. The positive electrode active material layer portion 21 </ b> A is provided except for one end portion (left end portion in FIG. 5) in a direction orthogonal to the longitudinal direction of the positive electrode plate 21 (hereinafter referred to as the width direction). That is, the positive electrode active material layer portion 21A is not provided in the portion along the longitudinal direction on one end side in the width direction of the positive electrode plate 21 (the edge portion 20a on one end side of the electrode bundle 20 shown in FIG. 2). An exposed portion 21B where the positive electrode plate 21 is exposed is formed. Since the exposed portion 21B functions as the positive electrode 20A, it is also referred to as a positive electrode exposed portion.

  The negative electrode plate 22 has a negative electrode active material layer portion 22A in which a negative electrode active material such as graphite is applied to both surfaces of a substrate made of, for example, copper foil. The negative electrode active material layer portion 22A is provided except for one end portion (the right end portion in FIG. 5) in a direction orthogonal to the longitudinal direction of the negative electrode plate 22 (hereinafter referred to as the width direction). That is, the negative electrode active material layer portion 22A is not provided in the portion along the longitudinal direction on one end side in the width direction of the negative electrode plate 22 (the end edge portion 20b on the other end side of the electrode bundle 20 shown in FIG. 2). In addition, an exposed portion 22B where the negative electrode plate 22 is exposed is formed. Since the exposed portion 22B functions as the negative electrode 20B, it is also referred to as a negative electrode exposed portion.

  The separators 23 and 24 have a role of electrically insulating the positive electrode plate 21 and the negative electrode plate 22, a role of holding an electrolyte solution (not shown), a role of allowing ions to pass, and a distance between the electrode plates 21 and 22. And is interposed between the positive electrode active material layer portion 21 </ b> A of the positive electrode plate 21 and the negative electrode active material layer portion 22 </ b> A of the negative electrode plate 22. As the separators 23 and 24, for example, a film made of polyethylene or polypropylene in which a large number of minute holes are formed is used. Here, the same separators 23 and 24 are used.

  In the laminate 25, the positive electrode plate 21 and the negative electrode plate 22 configured as described above are stacked with separators 23 and 24 being offset in the width direction as shown in FIG. In the central portion excluding the positive electrode exposed portion 21B and the negative electrode exposed portion 22B at both ends, an overlapping portion 25A in which the positive electrode plate 21, the separator 23, the negative electrode plate 22, and the separator 24 are stacked in this order is formed.

  In the electrode bundle 20 in which the laminated body 25 is wound and formed into a flat shape, the positive electrode exposed portion 21B is wound on the edge portion of one end thereof, and the negative electrode exposed portion 22B is wound on the edge portion of the other end. It will be turned. The positive electrode exposed portion 21B and the negative electrode exposed portion 22B in the wound state are joined to each other to form the positive electrode 20A and the negative electrode 20B, and the positive electrode current collector 31 is formed on the positive electrode exposed portion 21B that forms the positive electrode 20A. Negative electrode current collectors 32 are respectively coupled to negative electrode exposed portions 22B forming 20B.

  In the present embodiment, the electrode bundle 20 is formed in a hollow flat shape, and the positive electrode exposed portion 21B and the negative electrode exposed portion 22B at both ends of the electrode bundle 20 have a binding member 33 made of a conductive material such as metal, for example. 34 is mounted. The positive electrode side binding member 33 sandwiches the hollow positive electrode exposed portion 21B from the inside and the outside, and binds and bonds the stacked layers so that there is no gap, thereby forming the positive electrode current collecting tab 21C. The negative electrode side binding member 34 sandwiches the hollow negative electrode exposed portion 22B from the inner side and the outer side and binds and bonds the stacked layers so that there is no gap between them, thereby forming the negative electrode current collecting tab 22C. These bundling members 33 and 34 are joined to the positive electrode exposed portion 21B or the negative electrode exposed portion 22B by, for example, ultrasonic welding. As a result, the electrode bundle 20 is held in a hollow flat shape.

  The positive electrode side binding member 33 has a current collector (lead portion) 31a of the positive electrode current collector 31, and the negative electrode side binding member 34 has a current collector portion (lead portion) 32a of the negative electrode current collector 32. Joined by sonic welding or the like. As a result, the positive electrode 20A of the electrode bundle 20 is electrically connected to the positive electrode current collector 31 via the positive electrode current collecting tab 21C, and the negative electrode 20B of the electrode bundle 20 is connected to the negative electrode current collector via the negative electrode current collecting tab 22C. It is electrically connected to the body 32.

  The positive electrode current collector 31 and the negative electrode current collector 32 are provided with terminal connection portions 31b and 32b at positions above each when mounted, and the current collection portions 31a and 32a are paired from the terminal connection portions 31b and 32b. None of them extends downward. The current collectors 31a and 31a are arranged so as to sandwich the positive electrode side binding member 33 from the outside, and are respectively joined. The current collectors 32a and 32a are arranged so as to sandwich the negative electrode side binding member 34 from the outside. Each is joined.

  As shown in FIG. 2, the terminal connection portions 31 b and 32 b of the positive electrode current collector 31 and the negative electrode current collector 32 are respectively provided with positive electrode terminal members 35 that protrude outward from the through holes 12 a provided in the lid member 12. A negative terminal member 36 is connected. Insulating sheet members 40 are arranged on the upper and lower surfaces of the lid member 12 so as to correspond to the openings of the respective through holes 12a. With these insulating sheet members 40, the positive terminal member 35, the negative terminal member 36 and the lid member 12 are disposed. Is insulated.

[1-2. Configuration of cell case (exterior material)]
As described above, the cell case 10 is formed in a rectangular parallelepiped shape including six surfaces of the front surface portions 13 and 13 and the end surface portions 14 and 14, the lid member (upper surface portion) 12, and the bottom surface portion (lower surface portion) 15. If the cell case 10 is deformed in the event of an accident, an internal short circuit may occur. In particular, the current collectors 31a and 32a of the current collectors 31 and 32 are arranged in the immediate vicinity of the end face parts 14 and 14, and when the end face parts 14 and 14 are deformed inward, the current collector parts 31a and 32a are placed inside. There is a risk that the electrode will be deformed into the electrode bundle 20 adjacent to the current collectors 31a and 32a and contact the positive electrode plate 21 or the negative electrode plate 22 to cause an internal short circuit.

  Such inward deformation of the current collecting portions 31a and 32a may occur when the end surface portions 14 and 14 are buckled and deformed by receiving a compressive load in the vertical direction. The buckling deformation of the end surface portions 14 and 14 greatly affects not only the rigidity of the end surface portions 14 and 14 but also the rigidity of the front surface portions 13 and 13 orthogonal to the end surface portions 14 and 14. That is, if the rigidity of the front surface portions 13 and 13 is high, the buckling deformation of the end surface portions 14 and 14 may be avoided.

  In view of this, the cell case 10 is provided with a cross section deforming portion 16 for reinforcing rigidity at the front portions 13 and 13. The rigidity-enhancing cross-section deforming portion 16 is formed in a flat cross-sectional shape that differs from the flat plate, while the front portions 13 and 13 are formed in a flat plate shape. 14), the rigidity with respect to the force in the direction orthogonal to 14 is partially increased. In the present embodiment, a part of the front portions 13 and 13 is partially deformed inward to form a cross section deforming portion 16 for strengthening rigidity.

  That is, as shown in FIGS. 1 to 4, in the front portions 13, 13, a part of the front portions 13, 13 is deformed into a partial cylindrical shape inside without changing the plate thickness, and the cross-sectional deformation for rigidity enhancement is performed. Part 16 is formed. The rigidity-enhancing cross-section deforming portion 16 includes a partial cylindrical portion 16a having a center line in a direction orthogonal to the end surface portions 14, 14, and end wall portions 16b, 16c formed at both ends of the partial cylindrical portion 16a. Have Here, in consideration of press formability, both end wall portions 16b and 16c are inclined outward.

  Further, the formation region of the cross section deforming portion 16 for strengthening rigidity corresponds to the region (region A1 shown in FIG. 1) in which the current collecting portions 31a and 32a of the current collectors 31 and 32 extend in the vertical direction, Thereby, the rigidity of the area | region where the current collection parts 31a and 32a extend is improved. The area A1 shown in FIG. 1 does not include the area A2 on the upper end side of the front portions 13 and 13 (area close to the lid member 12), but the area A2 close to the lid member 12 This is because the rigidity also opposes the axial force (the force in the direction orthogonal to the end face portions 14 and 14), and thus it is not necessary to increase the rigidity.

  In addition, the region where the rigidity-enhancing cross-section deformed portion 16 is formed is a region (region W1 shown in FIG. 1) corresponding to the overlapping portion 25A of the stacked body 25 in the horizontal direction. Therefore, the cross-section deforming portion 16 for reinforcing rigidity is not formed in the region (region W2 shown in FIG. 1) corresponding to the exposed portions 21B and 22B exposed to the end side from the overlapping portion 25A outside the overlapping portion 25A. . In the region W2 corresponding to the exposed portions 21B and 22B, current collecting portions 31a and 32a are provided outside the exposed portions 21B and 22B (on the front portions 13 and 13 side), and the region W2 has a cross section for strengthening rigidity. When the portion 16 is formed, there is a possibility that the rigidity-enhancing cross-section deforming portion 16 interferes with the current collecting portions 31a and 32a, so that this is avoided. Of course, the rigidity-enhancing cross-sectional deformation part 16 is formed as close as possible to the end face part 14 within a range in which the possibility of interference with the current collecting parts 31a, 32a of the rigidity-enhancing cross-sectional deformation part 16 can be avoided.

[1-3. Installation on vehicle]
For example, as shown in FIGS. 7A and 7B, the vehicle secondary battery 1 configured in this way is assembled into a module case (small case) in a plurality (for example, about 5 to 8 pieces). ) 61 and 62 to be modularized. Further, as shown in FIG. 6, a plurality of module cases 61 and 62 are arranged in a battery case (large case) 70 including a battery tray 71 and a battery cover 72. Are stored side by side to form a battery pack 70P. Therefore, in the battery pack 70 </ b> P, the vehicle secondary battery 1 is stored in a double case structure of the module cases 61 and 62 and the battery case 70.
And this battery pack 70P is mounted in vehicles 2, such as an electric vehicle, as shown in FIG. In this example, the battery pack 70P is attached under the floor panel 4 of the passenger compartment 3 of the vehicle 2 (below the front seat 5F and the rear seat 5R).

[1-4. Action / Effect]
Since the vehicle secondary battery according to the present embodiment is configured as described above, for example, as shown in FIG. 9, in the cell case 10, a lid is formed from above the end surface portion 14 of the end portion of the lid member 12. When an external force F is applied to the member 12, buckling deformation of the end surface portion 14 is induced depending on the magnitude of the external force F, but the front surface portion 13, Since 13 is connected, front parts 13 and 13 counteract and prevent buckling deformation of end face part 14.

  The front surface portions 13 and 13 are formed with a cross section deforming portion 16 for reinforcing rigidity, and this portion is partially enhanced in rigidity against axial force (force in a direction perpendicular to the end surface portions 14 and 14). The resistance against the buckling deformation of the end face portion 14 is increased. On the other hand, since the rigidity with respect to the axial force is relatively low at a portion where the rigidity-enhancing cross-section deforming portion 16 is not formed, in particular, below the rigidity-enhancing cross-sectional deforming portion 16, the end face portion 14 starts buckling deformation. In this case, buckling deformation occurs from this point.

That is, if there is no rigidity-enhancing cross-section deforming portion 16, as shown in FIG. 9A, the end surface portion is located at the location 51 where the current collecting portions 31 a and 32 a of the current collectors 31 and 32 above the end surface portion 14 exist. 14 buckling deformation, deforming the current collecting portions 31a, 32a inward, entering the electrode bundle 20 adjacent to the current collecting portions 31a, 32a and contacting the positive electrode plate or the negative electrode plate, leading to an internal short circuit. is there.
On the other hand, when the cross section deforming portion 16 for strengthening rigidity is provided, as shown in FIG. 9B, the current collecting portions 31a and 32a of the current collectors 31 and 32 below the end surface portion 14 are not present. Since the rigidity-increasing cross-section deforming portion 16 is not formed at 52, when the buckling deformation of the end face portion 14 occurs, this occurs at this portion. Therefore, it is difficult to deform the current collecting portions 31a and 32a inward, and the risk of entering the electrode bundle 20 adjacent to the current collecting portions 31a and 32a and coming into contact with the positive electrode plate or the negative electrode plate can be avoided or reduced. The possibility of causing a short circuit can be avoided or reduced.

Further, in the case of the present embodiment, the rigidity-enhancing cross-section deforming portion 16 is formed without changing the plate thickness of the front portion 13, so that the weight of the cell case 10 is not increased, and inward of the case. Since the rigidity-enhancing cross-section deformed portion 16 is formed in a curved cylindrical shape, the thickness of the cell case 10 and the distance between the outer surfaces of the front portions 13 and 13 do not increase.
Of course, the cross-sectional deformation portion 16 for reinforcing rigidity of the front portion 13 protrudes inward, and the space for accommodating the electrode bundle 20 in the cell case 10 is reduced. However, the hollow portion of the electrode bundle 20 is reduced to reduce the space. It can also be reduced.

  Further, when the rigidity-enhancing cross-section deforming portion 16 is curved into a cylindrical curved surface shape, partial rigidity can be improved and the above-described effects can be obtained even by relatively slightly deforming. Therefore, a reduction in the space can be suppressed.

[2. Second Embodiment]
The vehicle secondary battery according to the second embodiment will be described with reference to FIG.
As shown in FIG. 10, the secondary battery for a vehicle according to the present embodiment is different from the first embodiment only in the configuration of the cell case 10A. That is, in the cell case 10A according to the present embodiment, the rigidity-enhancing cross-section deforming portion 16A formed on the front portions 13A and 13A is disposed in the same region as that of the first embodiment, and the thickness of the front portion 13A is changed. In addition, the outer surface side of the front portion 13A is formed in a concave shape and the inner surface side is formed in a convex shape in the same manner as the rigidity-enhancing cross-section deforming portion 16 in the first embodiment, but it is configured by a plurality of flat surfaces instead of a curved surface.

  Even in such a configuration, as in the first embodiment, it is difficult to deform the current collecting portions 31a and 32a inward, and the electrode bundle 20 adjacent to the current collecting portions 31a and 32a enters the electrode bundle 20 and contacts the positive electrode plate or the negative electrode plate. The possibility of causing an internal short circuit can be avoided or reduced.

[3. Third Embodiment]
The vehicle secondary battery according to the third embodiment will be described with reference to FIG.
As shown in FIGS. 11A and 11B, the vehicle secondary battery according to this embodiment is different from the first and second embodiments only in the configuration of the cell case 10A. That is, in the cell case 10b according to the present embodiment, the rigidity-enhancing cross-section deforming portion 16b formed on the front portions 13b and 13b is formed so that the outer surface side of the front portion 13 is flat and the inner surface is curved in a convex shape. The thickness is increased. Of course, the rigidity-enhancing cross-section deforming portion 16b is disposed in the same region as in the first embodiment.

  Even in such a configuration, as in the first embodiment, it is difficult to deform the current collecting portions 31a and 32a inward, and the electrode bundle 20 adjacent to the current collecting portions 31a and 32a enters the electrode bundle 20 and contacts the positive electrode plate or the negative electrode plate. The possibility of causing an internal short circuit can be avoided or reduced.

[4. Others]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention.
For example, the formation region of the rigidity-enhancing cross-section deformed portions 16, 16A, 16B corresponds to the region (region A1 shown in FIG. 1) in which the current collectors 31a, 32a of the current collectors 31, 32 extend in the vertical direction. However, the phrase “corresponding to the region A1 in which the current collectors 31a and 32a of the current collectors 31 and 32 extend” necessarily includes all the regions in which the current collectors 31a and 32a extend. The region where the current collecting portions 31a and 32a extend can be strengthened more rigidly than the other regions. For example, the region where the rigidity-enhancing cross-section deforming portions 16, 16A, 16B are formed is close to the boundary of the region where the current collecting portions 31a, 32a extend, but is not included up to this boundary. You may be made to do.

  In addition, although the formation region of the cross-section deforming portions 16, 16A, 16B for rigidity enhancement is a region corresponding to the overlapping portion 25A of the stacked body 25 in the horizontal direction (region W1 shown in FIG. 1), this is the overlapping portion. This is for avoiding the possibility of interference of the rigidity-enhancing cross-section deforming portion 16 with respect to the current collecting portions 31a and 32a provided on the front portions 13 and 13 side of the exposed portions 21B and 22B exposed to the end portion from 25A. If there is no risk of interference with the rigidity-enhancing cross-section deforming portion 16 (adverse effects of interference of the rigidity-enhancing cross-section deforming portion 16), the end face portion 14 is brought closer to form the rigidity-enhancing cross-sectional deforming portions 16, 16A, 16B. May be.

  Further, in the above embodiment, the rigidity-enhancing cross-section deforming sections 16, 16 </ b> A, and 16 </ b> B are basically employed on the inner side, but may be convex on the outer side.

DESCRIPTION OF SYMBOLS 1 Secondary battery for vehicles 10, 10A, 10B Cell case which is exterior member 11 Cell case main body 12 Cover member (upper surface part)
13, 13A, 13B Front part 14 End face part 15 Bottom part (lower face part)
16, 16A, 16B Rigidity-enhancing cross-sectional deformation part 20 Electrode bundle (element)
20a, 20b Edge part of electrode bundle 20 21 Positive electrode plate 21B Exposed part (positive electrode exposed part)
22 Negative electrode plate 22B Exposed part (negative electrode exposed part)
23 Separator 25 Laminate 25A Overlapping part 31 Positive electrode current collector (positive electrode lead)
32 Negative electrode current collector (negative electrode lead)
31a, 32a Current collector 35 Positive electrode terminal member 36 Negative electrode terminal member

Claims (6)

A laminated body in which a positive electrode plate and a negative electrode plate are offset and laminated via a separator is wound around a winding axis, and an electrode bundle formed into a flat shape,
At the edge of the electrode bundle, a current collector in which the positive electrode plate or the negative electrode plate is exposed from an overlapping portion of the laminate and is coupled to an exposed portion formed along the edge,
A pair of front portions that house the electrode bundle and the current collector and face the flat surface of the electrode bundle, a pair of end surface portions located at both ends of the pair of front portions, an upper surface portion, and a lower surface portion A secondary battery for a vehicle comprising: an exterior member formed in a rectangular parallelepiped shape, wherein the current collector is in proximity to any of the end face portions,
The current collector extends along the exposed portion;
The front portion is formed with a cross-sectional deformation portion for reinforcing rigidity extending in a direction intersecting with the end face portion,
The vehicular secondary battery, wherein the rigidity-enhancing cross-sectional deformation portion is formed corresponding to a region where the current collector extends. 2. The vehicular secondary battery according to claim 1, wherein the rigidity-enhancing cross-sectional deformable portion is formed to extend from a central portion of the front portion to a portion close to the end surface portion. The vehicular secondary battery according to claim 1, wherein the rigidity-enhancing cross-sectional deformation portion extends in a region corresponding to the overlapping portion of the laminate. The vehicular secondary battery according to any one of claims 1 to 3, wherein the rigidity-enhancing cross-section deforming portion is formed in a curved surface shape. The current collector is disposed with an upper end connected to a positive electrode terminal or a negative electrode terminal provided at an end of the upper surface, and a lower end extending to the vicinity of the lower end of the exposed portion. The secondary battery for vehicles according to any one of claims 1 to 4. As the current collector,
A positive electrode current collector coupled to a positive electrode exposed portion formed by exposing the positive electrode plate to one end edge side of the electrode bundle;
A negative electrode current collector coupled to a negative electrode exposed portion formed by exposing the negative electrode plate to the other end edge side of the electrode bundle,
The secondary battery for a vehicle according to any one of claims 1 to 5, wherein the positive electrode current collector and the negative electrode current collector are adjacent to the corresponding both end surface portions, respectively.

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