Power storage device

A power storage device includes a holder that includes a plurality of hole rows having a plurality of insertion holes and is provided to be longer in a longitudinal direction than in a width direction. The holder includes a first long side surface, a second long side surface, a first fragile portion, and a second fragile portion. A first thin portion of the holder is disposed adjacent to a fourth insertion hole in the width direction. A second thin portion of the holder is disposed adjacent to the first insertion hole in the width direction. When a virtual straight line passing through the first thin portion and the second thin portion is taken as a virtual breaking line, the first fragile portion and the second fragile portion are disposed at positions through which the virtual breaking line passes or in a vicinity of the virtual breaking line.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2018-046856 filed on Mar. 14, 2018, incorporated herein by reference in its entirety.

BACKGROUND

1. Technical Field

The disclosure relates to a power storage device.

2. Description of Related Art

As a power storage device, a power storage device including a plurality of cylindrical batteries is known, and for example, a power storage device including a plate-shaped holder in which a plurality of insertion holes is formed and a plurality of cylindrical batteries inserted into the insertion holes is known.

In the power storage device as described above, when a large external force is applied to the holder from the outside, the holder deforms. As the holder deforms, the cylindrical battery inserted into the holder is likely to be damaged.

Therefore, a power storage device has been suggested, in which damage to the cylindrical battery is suppressed even when a large external force is applied to the holder from the outside. For example, Japanese Unexamined Patent Application Publication No. 2016-115599 (JP 2016-115599 A) discloses a power storage device that includes a plurality of cylindrical batteries and a holder. In JP 2016-115599 A, the holder has a rectangular shape in a plan view, and the peripheral surface of the holder includes a pair of long side surfaces.

In the holder, a plurality of insertion holes into which the cylindrical batteries are inserted is formed, and on each long side surface of the holder, a fragile portion is formed.

In the power storage device described above, when an external force is applied to a power storage module, stress is concentrated on the fragile portion formed on each long side surface, breakage starts from each fragile portion, and the holder is split.

Thus, in the power storage device disclosed in JP 2016-115599 A, when a large external force is applied to the power storage device, the holder is configured to be divided before the holder is greatly deformed by the external force. Then, when the holder is divided, a plurality of holder pieces is produced, and each holder piece is displaced relative to each other.

In this way, the damage to the cylindrical battery is suppressed by dividing the holder and moving the cylindrical battery along with each holder piece before the holder is deformed by the external force.

SUMMARY

In the power storage device, when an external force is applied to the holder and the holder is broken, it is likely that the breaking line of the holder passes through the insertion hole. Then, when the external force is further applied to one holder piece, the holder piece relatively moves with respect to the other holder piece along the breaking line. In this case, when the breaking line passes the insertion hole, the cylindrical battery inserted in the insertion hole is likely to be deformed or damaged as the holder piece moves.

The disclosure provides a power storage device in which passing of a breaking line of a holder through an insertion hole is suppressed when an external force is applied to the holder.

An aspect of the present disclosure relates to a power storage device including a holder and a unit battery. The holder includes a plurality of hole rows having a plurality of insertion holes and is provided to be longer in a longitudinal direction than in a width direction, and the unit battery is inserted into each of the insertion holes. The holder includes a first long side surface and a second long side surface extending in the longitudinal direction and arranged in the width direction. The holder includes a first fragile portion on the first long side surface. The holder includes a second fragile portion on the second long side surface. The plurality of hole rows include a first hole row and a second hole row closer to the second long side surface than the first hole row.

The first hole row includes a first insertion hole and a second insertion hole adjacent to the first insertion hole in the longitudinal direction. The second hole row includes a third insertion hole and a fourth insertion hole adjacent to the third insertion hole in the longitudinal direction.

A first thin portion of the holder positioned between the first insertion hole and the second insertion hole is disposed adjacent to the fourth insertion hole in the width direction. A second thin portion of the holder positioned between the third insertion hole and the fourth insertion hole is disposed adjacent to the first insertion hole in the width direction.

When a virtual straight line passing through the first thin portion and the second thin portion is taken as a virtual breaking line, the first fragile portion and the second fragile portion are disposed at positions through which the virtual breaking line passes or in a vicinity of the virtual breaking line.

With the power storage device according to the aspect of the disclosure, when a large external force is applied to the holder on the first long side surface, cracks develop from the first and second fragile portions. Since the first fragile portion and the second fragile portion are disposed at the positions through which the virtual breaking line passes or in the vicinity of the virtual breaking line, the breaking lines developing from the first fragile portion and the second fragile portion tend to reach the virtual breaking line.

When each crack reaches the virtual breaking line, the holder is mainly connected by the first thin portion and the second thin portion, and thus stress tends to concentrate on the first fragile portion and the second fragile portion. As a result, the breaking line is formed to pass through the first fragile portion and the second fragile portion, and the holder is split such that two holder pieces are formed.

In this way, when the holder is broken, the breaking line easily passes through the thin portion, and the passage of the breaking line through the insertion hole is suppressed. Therefore, it is possible to suppress damage to the unit battery when the holder pieces move relatively.

In the power storage device according to the aspect, the virtual breaking line may include a first portion positioned on the first long side surface and a second portion positioned in the first thin portion, and when a line segment of the virtual breaking line positioned between the first portion and the second portion is taken as a first virtual line segment and a portion of the holder which is positioned close to the first long side surface with respect to the first virtual line segment is taken as a first region, at least a part of the first fragile portion may be positioned in the first region when the first fragile portion is positioned in the vicinity of the virtual breaking line.

With the power storage device according to the aspect of the disclosure, a crack developing from the first fragile portion easily reaches the virtual breaking line.

In the power storage device according to the aspect, the plurality of hole rows may include a third hole row provided at a position adjacent to the second long side surface, the third hole row may include a fifth insertion hole and a sixth insertion hole adjacent to the fifth insertion hole in the longitudinal direction, the virtual breaking line may pass through a third thin portion positioned between the fifth insertion hole and the sixth insertion hole, the virtual breaking line may include a third portion positioned on the second long side surface and a fourth portion positioned in the third thin portion, and when a line segment of the virtual breaking line positioned between the third portion and the fourth portion is taken as a second virtual line segment and a portion of the holder which is positioned close to the second long side surface with respect to the second virtual line segment is taken as a second region, at least a part of the second fragile portion may be positioned in the second region when the second fragile portion is positioned in the vicinity of the virtual breaking line.

With the power storage device according to the aspect of the disclosure, a crack developing from the second fragile portion easily reaches the virtual breaking line.

In the power storage device according to the aspect, the insertion holes of each of the hole rows may be arranged in the longitudinal direction, each of the hole rows may be arranged in the width direction, and the virtual breaking line may pass through the thin portion positioned between the insertion holes in each of the hole row.

With the power storage device according to the aspect of the disclosure, the breaking line easily passes through each thin portion, and thus it is possible to suppress passage of the breaking line through the insertion hole.

In the power storage device according to the aspect, the holder may include a third fragile portion on the first long side surface, when a virtual line passing through the second fragile portion and extending in the width direction is taken as a symmetrical virtual line, the first hole row may include a seventh insertion hole and an eighth insertion hole provided symmetrically with the first insertion hole and the second insertion hole with respect to the symmetrical virtual line, a fourth thin portion may be included between the seventh insertion hole and the eighth insertion hole, the second hole row may include a ninth insertion hole and a tenth insertion hole provided symmetrically with the third insertion hole and the fourth insertion hole with respect to the symmetrical virtual line, a fifth thin portion may be included between the ninth insertion hole and the tenth insertion hole, and when a virtual straight line passing through the fourth thin portion and the fifth thin portion is taken as another virtual breaking line, the third fragile portion may be disposed at a position through which the other virtual breaking line passes, or in a vicinity of the other virtual breaking line.

With the power storage device according to the aspect of the disclosure, the breaking line is easily formed to pass through the fourth thin portion and the fifth thine portion, and thus it is possible to suppress passage of the breaking line through the insertion hole.

With the power storage device according to the aspect of the disclosure, it is possible to suppress passage of the breaking line of the holder through the insertion hole when an external force is applied to the holder.

DETAILED DESCRIPTION

Power storage devices according to Embodiments 1, 2 will be described with reference toFIGS. 1 to 23. The same constituent elements throughFIGS. 1 to 23are denoted by the same reference signs and thus descriptions thereof will not be repeated (in the present specification, “the same configuration” includes “substantially the same configuration” in its meaning).

FIG. 1is a schematic view of a battery pack200. The battery pack200includes power storage devices1A,1B, and fixation plates201,202.

The power storage devices1A,1B are disposed at an interval in an X direction. The fixation plate201is fixed to a first end of the power storage device1A by bolts210,211, and is fixed to a first end of the power storage device1B by bolts212,213.

The fixation plate201is fixed to a floor panel or the like of a vehicle by bolts214,215,216. In this way, the fixation plate201connects the power storage devices1A,1B to each other, and fixes the power storage devices1A,1B to the floor panel.

The fixation plate202is fixed to a second end of the power storage device1A by bolts220,221, and is fixed to a second end of the power storage device1B by bolts222,223. The fixation plate202is also fixed to the floor panel by bolts (not shown).

In this way, the fixation plate202also connects the power storage devices1A,1B to each other and fixes the power storage devices1A,1B to the floor panel.

Next, the configuration of the power storage device1A will be described. Since the configurations of the power storage devices1A,1B are the same, the configuration of the power storage device1A will be mainly described.

FIG. 2is an exploded perspective view of the power storage device1A. The power storage device1A includes a holder2, cylindrical batteries3, a resin case4, a positive electrode bus bar module5, a negative electrode bus bar module6, an undercover7, and a connection bus bar module8.

The holder2is formed in a substantially plate shape, and, for example, the holder2is formed of a metal material. A plurality of insertion holes10penetrating vertically is formed in the holder2. The specific configuration of the holder2will be described later.

The power storage device1A includes a plurality of cylindrical batteries3, and cylindrical batteries3are each inserted into the insertion holes10. A positive electrode11is formed at the upper end of the cylindrical battery3and a negative electrode12is formed at the lower end of the cylindrical battery3. The upper end of each cylindrical battery3protrudes from the top surface of the holder2. The resin case4is provided to cover the cylindrical batteries3from above.

The positive electrode bus bar module5includes a plurality of positive electrode bus bars14A,14B,14C,14D, the positive electrode bus bars14A,14B,14C,14D are arranged at intervals in a Y direction, and the positive electrode bus bars14A,14B,14C,14D each connect the positive electrodes11of cylindrical batteries3in parallel.

The negative electrode bus bar module6includes a plurality of negative electrode bus bars20B,20C,20D,20E, the negative electrode bus bars20B,20C,20D,20E are arranged at intervals in the Y direction, and the negative electrode bus bars20B,20C,20D,20E each connect the negative electrodes12of the cylindrical batteries3in parallel.

The connection bus bar module8includes a plurality of connection bus bars26B,26C,26D,26E. The connection bus bar26B connects the positive electrode bus bar14B and the negative electrode bus bar20B to each other. The connection bus bars26C,26D connect the positive electrode bus bars14C,14D and the negative electrode bus bars20C,20D, respectively. The connection bus bar26E is connected to the negative electrode bus bar20E.

Next, a configuration of the holder2will be described in detail. The holder2is formed in a plate shape, and the holder2includes a top surface28, a bottom surface29, and peripheral surfaces27.

FIG. 3is a plan view illustrating the holder2, and is a plan view when viewed from above the holder2. As illustrated inFIG. 3, the holder2has a rectangular shape. A length of the holder2in the longitudinal direction L is longer than that of the holder2in the width direction W.

InFIG. 3, the holder2is disposed such that the width direction W coincides with the X direction and the longitudinal direction L coincides with the Y direction.

The peripheral surfaces27of the holder2includes long side surfaces30,31, and short side surfaces32,33. InFIG. 1, the long side surface30is positioned on the outer surface203of the battery pack200, and the long side surface31is positioned on the power storage device1B side.

Returning toFIG. 3, the long side surfaces30,31extend in the longitudinal direction L, and the long side surfaces30,31are arranged in the width direction W. The short side surfaces32,33extend in the width direction W and are arranged in the longitudinal direction L.

In the short side surface32, bolt holes40,41are formed, and in the short side surface33, bolt holes42,43are formed.

The bolts210,211inFIG. 1are inserted into the bolt holes40,41, and the fixation plate201inFIG. 1is fixed to the holder2. Similarly, the bolts220,221are inserted into the bolt holes42,43and the fixation plate202inFIG. 1is fixed to the holder2.

In this way, the short side surface32of the holder2is fixed to the floor panel by the fixation plate201, and the short side surface33of the holder2is fixed to the floor panel by the fixation plate202. Therefore, the holder2is substantially fixed at both ends.

In the holder2, a plurality of hole rows35,36,37,38is formed. The hole row35is formed by a plurality of insertion holes10arranged at equal intervals in the longitudinal direction L with a space therebetween. Similarly, the hole rows36,37,38are each formed by a plurality of insertion holes10arranged at equal intervals in the longitudinal direction L with a space therebetween.

The insertion hole10is formed to extend from the top surface28of the holder2to the bottom surface, and the opening of each insertion hole10is formed in a circular shape, and the radius of each opening is “R”.

The hole row35(which is an example of the first hole row) is formed close to the long side surface30, and the hole row36(which is an example of the second hole row) is formed at a position closer to the long side surface31(which is an example of the second long side surface) than the hole row35. The hole row36is shifted to the short side surface32by a half of about the radius R compared to the hole row35.

The hole row37is formed at a position closer to the long side surface31than the hole row36, and the hole row37is shifted to the short side surface33by about the radius R compared to the hole row36.

The hole row38is formed at a position closer to the long side surface31than the hole row37, and the hole row38is shifted to the short side surface32by about the radius R compared to the hole row37. The hole row38(which is an example of the third hole row) is formed adjacent to the long side surface31. That is, the insertion holes10in the holder2are formed in a zigzag shape.

FIG. 4is an enlarged plan view of a part of the holder2illustrated in FIG.3. The hole row35includes an insertion hole10A (which is an example of the first insertion hole) and an insertion hole10B (which is an example of the second insertion hole).

The insertion hole10B is formed to be adjacent to the insertion hole10A in the longitudinal direction L. In a portion of the holder2positioned between the insertion hole10A and the insertion hole10B, a thin portion50A (which is an example of the first thin portion) is formed.

The hole row36includes an insertion hole10C (which is an example of the third insertion hole) and an insertion hole10D (which is an example of the fourth insertion hole). The insertion hole10D is formed to be adjacent to the insertion hole10C in the longitudinal direction L. A thin portion50B (which is an example of the second thin portion) is formed between the insertion hole10C and the insertion hole10D in the holder2.

The thin portion50A (which is an example of the first thin portion) and the insertion hole10D (which is an example of the fourth insertion hole) are adjacent to each other in the width direction W, and specifically, the thin portion50A and the center OD of the opening of the insertion hole10D are adjacent to each other in the width direction W.

Further, the insertion hole10A (which is an example of the first insertion hole) and the thin portion50B (which is the example of the second thin portion) are adjacent to each other in the width direction W, and specifically, the center OA of the opening of the insertion hole10A and the thin portion50B are adjacent to each other in the width direction W.

A thin portion49A is formed between the insertion hole10A (which is the example of the first insertion hole) and the insertion hole10D (which is the example of the fourth insertion hole).

The hole row37includes an insertion hole10E and an insertion hole10F. The insertion hole10F is formed to be adjacent to the insertion hole10E in the longitudinal direction L. A thin portion50C is formed between the insertion hole10E and the insertion hole10F.

The thin portion50C and the insertion hole10C are adjacent to each other in the width direction W, and specifically, the thin portion50C and the center OC of the opening of the insertion hole10C are adjacent to each other in the width direction W. Further, the thin portion50B and the insertion hole10F are adjacent to each other in the width direction W, and specifically, the center OF of the opening of the insertion hole10F and the thin portion50B are adjacent to each other in the width direction W. A thin portion49B is formed between the insertion hole10C and the insertion hole10F.

The hole row38(which is an example of the third hole row) includes an insertion hole10G (which is an example of the fifth insertion hole) and an insertion hole10H (which is an example of the sixth insertion hole). The insertion hole10H is formed to be adjacent to the insertion hole10G in the longitudinal direction L. The insertion hole10H is formed to be adjacent to the insertion hole10G in the longitudinal direction L. A thin portion50D (which is an example of the third thin portion) is formed between the insertion hole10G and the insertion hole10H.

The thin portion50D and the insertion hole10E are formed to be adjacent to each other in the width direction W. Specifically, the thin portion50D and the center OE of the opening of the insertion hole10E are adjacent to each other in the width direction W.

Further, the thin portion50C and the insertion hole10H are formed to be adjacent to each other in the width direction W, and specifically, the thin portion50C and the center OH of the insertion hole10H are adjacent to each other in the width direction W. A thin portion49C is formed between the insertion hole10H and the insertion hole10E.

As described above, in the holder2, a plurality of thin portions50A,50B,50C,50D and thin portions49A,49B,49C are formed by a plurality of insertion holes10, and each of thin portions50A,50B,50C,50D,49A,49B,49C is thin in thickness. For example, the distance between the opening edge portion of the insertion hole10A and the long side surface30is taken as the length L10, and the distance between the opening of the insertion hole10G and the long side surface31is taken as the length L11. In this case, the thickness of each of the thin portions50A,50B,50C,50D and the thickness of each of the thin portions49A,49B,49C are smaller than the lengths L10, L11.

InFIG. 4, the virtual breaking line L1is a virtual straight line passing through the thin portion50A and the thin portion50B. In the embodiment, the virtual breaking line L1passes through the thin portions50A,50B,50C,50D and the thin portions49A,49B,49C.

Returning toFIG. 3, a frangible or fragile portion51is formed on the long side surface30of the holder2, and a frangible or fragile portion52is formed on the long side surface31. The fragile portion52is formed at the center of the long side surface31in the longitudinal direction L. The fragile portion51is positioned closer to the short side surface32than the center of the long side surface30in the longitudinal direction L.

InFIG. 4, the fragile portion51is formed at a position adjacent to the thin portion50A in the width direction W, and the fragile portion52is formed at a position adjacent to the thin portion50D in the width direction W.

FIG. 5is a perspective view of the fragile portion51and a configuration around the fragile portion51. In the embodiment, the fragile portion51is a cutout portion formed in the long side surface30. The fragile portion51is formed to extend from the top surface28of the holder2to the bottom surface29.

The inner surface of the fragile portion51includes inner side surfaces60,61and inclined surfaces62,63. The inner side surface60and the inner side surface61extends from the long side surface30in the width direction W, and are arranged at an interval in the longitudinal direction L. The inclined surface62is connected to the inner side surface60, and the inclined surface63is connected to the inner side surface61. The inclined surface62and the inclined surface63are formed to approach each other as they become distant from the long side surface30. At a distal end of the fragile portion52, an apex side64is formed.

FIG. 6is a plan view of the fragile portion51and the configuration around the fragile portion51. The thin portion50A is the thinnest portion between the insertion hole10A and the insertion hole10B. In Embodiment 1, the thin portion50A is positioned on a virtual line L2passing through the center OA of the insertion hole10A and the center OB of the insertion hole10B.

A portion P1on the virtual breaking line L1(which is an example of the first portion) is positioned on the long side surface30, a portion P2on the virtual breaking line L1(which is an example of the second portion) is positioned in the thin portion50A. The virtual line segment LL1inFIG. 6is a line segment of the virtual breaking line L1between the portion P1and the portion P2.

FIG. 7is a plan view of a disposition relationship between the virtual line segment LL1and the fragile portion51. InFIG. 7, a region R1is a portion of the holder2positioned close to the long side surface30with respect to the virtual line segment LL1.

When the fragile portion51is positioned in the vicinity of the virtual breaking line L1, at least a part of the fragile portion51is positioned within the region R1. In the example illustrated inFIG. 7, substantially half of the fragile portion51is positioned within the region R1. The apex side64of the fragile portion51is positioned within the region R1.

FIG. 8is another perspective view of the fragile portion52and a configuration around the fragile portion52. In the embodiment, the fragile portion52is a cutout portion formed on the long side surface31. The fragile portion52is formed to extend from the top surface28of the holder2to the bottom surface29.

The inner surface of the fragile portion52includes inner side surfaces65,66and inclined surfaces67,68. The inner side surface65and the inner side surface66extend from the long side surface31in the width direction W, and the inner side surface65and the inner side surface66are arranged in the longitudinal direction L with a space therebetween.

The inclined surface67is connected to the inner side surface65, and the inclined surface68is connected to the inner side surface66. The inclined surface67and the inclined surface68are formed to approach each other as they become distant from the long side surface31. At a distal end of the fragile portion52, an apex side69is formed.

FIG. 9is a plan view of the fragile portion52and the configuration around the fragile portion52. The thin portion50D is the thinnest portion between the insertion hole10G and the insertion hole10H. The thin portion50D is positioned on a virtual line L3passing through the center OG of the insertion hole10G and the center OH of the insertion hole10H.

A portion P3(which is an example of the third portion) of the virtual breaking line L1is positioned on the long side surface31, and a portion P4(which is an example of the fourth portion) is positioned in the thin portion50D. The virtual line segment LL2illustrated inFIG. 9is a line segment positioned between the portion P3and the portion P4.

FIG. 10is a plan view of a disposition relationship between a virtual line segment LL2and the fragile portion52. A region R2illustrated inFIG. 10is a portion positioned closer to the long side surface31with respect to the virtual line segment LL2.

When the fragile portion52is positioned in the vicinity of the virtual breaking line L1, at least a part of the fragile portion52is positioned within the region R2. In the example illustrated inFIG. 10, the apex side69is formed at a position adjacent to the thin portion50D in the width direction W.

In the battery pack200configured as described above, a large load may be applied from the outside in some cases.

FIG. 11is a perspective view of a state in which a load is applied to an outer surface203of the battery pack200from a crushing element230. As illustrated inFIG. 12, in this state, the crushing element230applies a load to the holder2.FIG. 12is a plan view of a state in which a load of an external force is applied from the crushing element230to the holder2.

In the example illustrated inFIG. 12, the crushing element230is in contact with the center of the long side surface30in the longitudinal direction L. At this time, the holder2is fixed at the short side surface32and the short side surface33, and the holder2tend to deform such that the center in the longitudinal direction L is bent, and internal stress is generated in the holder2.

FIG. 13is an enlarged plan view of a part of the holder2in the state illustrated inFIG. 12. The apex side64is positioned at the distal end of the fragile portion51which is a cutout portion, and stress is likely to concentrate on the apex side64by the load from the crushing element230. For this reason, a crack develops from the apex side64. The apex side64is formed within the region R2illustrated inFIG. 7, and the crack developing from the apex side64tends to reach the virtual breaking line L1.

In particular, since the apex side64is formed to be adjacent to the thin portion50A in the width direction W, the crack developing from the apex side69tends to reach the thin portion50A.

Even in the fragile portion52, by the load from the crushing element230, stress is likely to concentrate on the apex side69of the fragile portion52, and the crack from the apex side69develops. As illustrated inFIG. 10, the fragile portion52is positioned within a region R4, and the fragile portion52is positioned in the vicinity of the virtual breaking line L1. Therefore, a crack developing from the fragile portion52tends to reach the virtual breaking line L1.

In particular, since the fragile portion52is formed at a position facing the contact position of the crushing element230with the long side surface30, a load tends to be applied to the fragile portion52so as to spread equally in the longitudinal direction L. As a result, the crack developing from the fragile portion52tends to develop in the width direction W and is likely to reach the thin portion50D.

As described above, when a crack developing from each of the fragile portions51,52reaches the virtual breaking line L1, the rigidity of a portion of the holder2through which the virtual breaking line L1passes becomes lowered, and it is likely that the crack develops or breakage is generated along the virtual breaking line L1.

Specifically, when the crack from the fragile portion51reaches the thin portion50A and the crack from the fragile portion52reaches the thin portion50D, the holder2is in a state of being connected by the thin portions49A,50B,49B,50C,49C and is in a state of being connected with a small area.

As a result, stress tends to concentrate on the thin portions49A,50B,49B,50C,49C, cracks are generated in the thin portions49A,50B,49B,50C,49C and the holder2is likely to be broken.

As described above, in the embodiment, it is possible to form the breaking line L8to pass through the thin portions50A,49A,50B,49B,50C,49C,50D, and it is possible to suppress passage of the breaking line L8to pass through the insertion hole10.

When the holder2is broken by the breaking line L8, the holder2is split into the holder piece2A and the holder piece2B.

Even after the holder2is split into the holder pieces2A,2B, when the crushing element230further presses the holder2, the holder piece2A moves relative to the holder piece2B along the breaking line L8.

As the breaking line L8goes from the long side surface30to the long side surface31, the breaking line L8runs in a direction from the short side surface32to the short side surface33.

FIG. 14is a plan view of a state in which the holder piece2A is moved relative to the holder piece2B.

As the holder2is split by the breaking line L8, a breaking surface71is formed in the holder piece2A, and a breaking surface72is formed in the holder piece2B.

Similarly to the breaking line L8, as the breaking surfaces71,72go from the long side surface30to the long side surface31, the breaking surfaces71,72also extends in the direction from the short side surface32to the short side surface33.

Therefore, the holder piece2A and the holder piece2B move along the breaking surfaces71,72, and the holder pieces2A,2B move in the longitudinal direction L and the width direction W, respectively.

FIG. 15is a plan view of a holder2C1according to a comparative example. A frangible or fragile portion51A is formed on a long side surface30of the holder2C1, and a frangible or fragile portion52A is formed on a long side surface31. The fragile portion51A and the fragile portion52A are opposite to each other in the width direction W. A plurality of insertion holes10is positioned between the fragile portion51A and the fragile portion52A.

The fragile portions51A,52A are formed closer to the short side surface32than the centers of the long side surfaces30,31in the longitudinal direction L.

FIG. 16is a plan view of a state in which the holder2C1is pressed by a crushing element230. Since a plurality of insertion holes10is positioned between the fragile portion51A and the fragile portion52A, when the crushing element230presses the center of the long side surface30, the crack developing from the fragile portion51A is likely to reach the insertion holes10. Further, the crack developing from the fragile portion52A is likely to reach the insertion holes10.

As a result, the breaking line L9is likely to pass through the insertion holes10positioned between the fragile portion51A and the fragile portion52A. The holder2is split into a holder piece2D and a holder piece2E by the breaking line L9. Then, furthermore, the crushing element230presses the holder piece2E, which, in turn, moves relative to the holder piece2D in the width direction W.

In this case, in the insertion hole10positioned between the fragile portion51A and the fragile portion52A, there is a possibility that the cylindrical battery inserted into the insertion hole10is pressed by the holder pieces2D,2E and damaged.

On the other hand, in the holder2according to the embodiment, as illustrated inFIG. 13, passage of the breaking line L8through the insertion hole10is suppressed, and thus occurrence of damage as described above is suppressed.

Furthermore, in the holder2C1according to the comparative example, the holder piece2E moves with respect to the holder piece2D just in the width direction W.

On the other hand, as illustrated inFIG. 14, in the holder2according to the embodiment, the holder pieces2A,2B are displaced in the longitudinal direction L.

That is, since the holder2according to the embodiment is consumed for deformation in the longitudinal direction L when the load from the crushing element230is the same, the displacement amount of the holder piece2A of the holder2in the width direction W can be suppressed so as to be smaller than the displacement amount of the holder piece2D of the comparative example in the width direction W.

Therefore, contact of the holder piece2A with the power storage device1B adjacent to the power storage device1A can be suppressed, and thus damage to the power storage device1B can be suppressed.

In the embodiment, have been described with an example in which the fragile portion51and the fragile portion52are disposed in the vicinity of the virtual breaking line L1has been described, but the fragile portion51and the fragile portion52may be formed at positions through which the virtual breaking line L1passes.

FIG. 17is a plan view of a holder in which the fragile portions51,52are formed at positions through which a virtual breaking line L1passes.

In the holder2, the fragile portion51is formed at a position overlapping with the virtual breaking line L1, the fragile portion52is also formed at a position overlapping with the virtual breaking line L1.

Since the fragile portions51,52are formed, the sectional area of the holder2decreased at the position through which the virtual breaking line L1passes.

Therefore, when a load is applied from a crushing element230to the holder2, stress tends to concentrate along the virtual breaking line L1, and thus the holder2is broken along the virtual breaking line L1. Specifically, the breakage of the breaking line occurs so as to pass through thin portions50A,49A,50B,49B,50C,49C,50D. In this way, it is possible to obtain the same effect as the embodiment described above.

One of the fragile portion51and the fragile portion52may be formed at a position overlapping with the virtual breaking line L1and the other may be formed in the vicinity of the virtual breaking line L1. The configuration of the power storage device1A has been described above in detail, and the power storage device1B is configured similarly to that of the power storage device1A.

A power storage device1C according to Embodiment 2 will be described with reference toFIG. 18and the like. The configuration of the power storage device1C is substantially the same as that of the power storage device1A except for the holder.

FIG. 18is a plan view of a holder2C of the power storage device1C. A frangible or fragile portion51and a frangible or fragile portion80are formed on a long side surface30of the holder2C, and a frangible or fragile portion52is formed on a long side surface31.

FIG. 19is a plan view of fragile portions51,52,80and the configuration around the fragile portions. Here, a symmetrical virtual line L20is a virtual straight line that passes through the apex side69of the fragile portion52and extends in the width direction W.

Even in Embodiment 2, each of hole rows35,36,37,38includes a plurality of insertion holes10arranged at equal intervals in the longitudinal direction L.

On the other hand, in Embodiment 2, the insertion holes10other than the insertion holes10A to10H described in Embodiment 1 will be described as the insertion holes10associated with the fragile portion80.

The hole row35includes an insertion hole10A1(which is an example of the seventh insertion hole) formed at a position symmetrical to the insertion hole10A with respect to the symmetrical virtual line L20. Further, the hole row35includes an insertion hole10B1(which is an example of the eighth insertion hole) formed at a position symmetrical to the insertion hole10B with respect to the symmetrical virtual line L20. A thin portion50A1(which is an example of the fourth thin portion) is formed between the insertion hole10A1and the insertion hole10B1.

The hole row36includes an insertion hole10C1(which is an example of the seventh insertion hole) formed at a position symmetrical to the insertion hole10C with respect to the symmetrical virtual line L20. Further, the hole row36includes an insertion hole10D1(which is an example of the eighth insertion hole) formed at a position symmetrical to the insertion hole10D with respect to the symmetrical virtual line L20. A thin portion50B1(which is an example of the fifth thin portion) is formed between the insertion hole10C1and the insertion hole10D1.

The hole row37includes an insertion hole10F1formed at a position symmetrical to the insertion hole10F with respect to the symmetrical virtual line L20. A thin portion50C1is formed between the insertion hole10E and the insertion hole10F1.

Here, the virtual breaking line L21(which is an example of another virtual breaking line) is a virtual straight line passing through thin portions50A1,49A1,50B1,49B1,50C1,49C1,50D.

FIG. 20is a plan view of the fragile portion80and the configuration around the fragile portion80. The part P5of a virtual breaking line L21is positioned on the long side surface30, the part P6is positioned in a thin portion50A1.

The virtual line segment LL3is a line segment positioned between the part P1and the part P2of the virtual breaking line L21.

FIG. 21is a plan view of a disposition relationship between the virtual line segment LL3and the fragile portion80. InFIG. 21, the region R3is a region of the holder2closer to the virtual line segment LL3with respect to the long side surface30.

“The fragile portion80is positioned in the vicinity of the virtual breaking line L21” means that at least a part of the fragile portion80is positioned within the region R3.

In Embodiment 2, the distal end of the fragile portion80is formed to be tapered as it becomes distant from the long side surface30. At the distal end of the fragile portion80, the apex side81is formed, which is similar to the apex side64of the fragile portion51. The apex side81is adjacent to the thin portion50A1in the width direction W.

A case in which an external force is applied to the holder2C configured as described above will be described.FIG. 22is a plan view when the crushing element230presses the center of the long side surface30in the longitudinal direction L.

Here, when the crushing element230presses the long side surface30, cracks develop from the apex sides64,69,81. Since the apex side81is provided to be adjacent to the thin portion50A1, the crack developing from the apex side81tends to reach the thin portion50A1. Further, the crack developing from the apex side69of the fragile portion52tends to reach the thin portion50D.

Therefore, the holder2C is in a state of being connected mainly by the thin portions49A1,50B1,49B1,50C1,49C1,50D, and stress tends to concentrate on each of the thin portions49A1,50131,49B1,50C1,49C1,50D. As a result, the breaking line L12is formed to pass through the thin portions50A1,49A1,50B1,49B1,50C1,49C1,50D. The breaking line L12is inclined such that, as the breaking line L12goes from the long side surface30to the long side surface31, the breaking line L12runs toward the short side surface32from the short side surface33.

Even in the embodiment, since the fragile portion51and the fragile portion52are formed, the breaking line L8is formed. For this reason, in the holder2C, it is also possible to suppress passage of the breaking lines L12, L8through the insertion holes10.

When the breaking line L8and the breaking line L12are formed, the holder2C is split into holder pieces2F,2G,2H.

Then, when the crushing element230further presses the holder piece2G, the holder pieces2F,2G,2H move relative to each other.

FIG. 23is a plan view of a state in which the holder piece2G is further pressed by the crushing element230after the holder2C is broken.

When the holder2C is broken at breaking lines L12, L8, a breaking surface85is formed in the holder piece2F. In the holder piece2G, a breaking surface86and a breaking surface87are formed. Similarly, in the holder piece2H, a breaking surface88is formed.

When the holder piece2G moves in the width direction W, the holder piece2F moves along the breaking surface86. In this case, since the breaking surface86is inclined such that, as the breaking surface86goes from the long side surface30to the long side surface31, the breaking surface86extends in the direction from the short side surface33to the short side surface32, the holder piece2F moves in the width direction W and the longitudinal direction L. Specifically, as the breaking surface86moves in the width direction W, the breaking surface86moves in the direction from the short side surface32to the short side surface33.

Similarly, as the holder piece2H moves in the width direction W, the holder piece2H moves in a direction from the short side surface33to the short side surface32.

As described above, in the holder2C, it is also possible to move the holder piece2F and the holder piece2H in the longitudinal direction L by the load from the crushing element230.

As described above, since the load from the crushing element230is also consumed for deformation in the longitudinal direction L, it is possible to suppress large deformation of the holder2C in the load direction (width direction W) of the crushing element230.

In Embodiment 2, an example in which the fragile portion80is formed in the vicinity of the virtual breaking line L21has been described, but the fragile portion80may be formed at any position where the virtual breaking line L21passes.

In Embodiment 1, 2 described above, an example in which the cutout portion is employed as the fragile portion has been described, but the fragile portion is not limited to the cutout portion, and anything in which, when a load is applied from the outside, stress concentrates and a crack is generated may be used. For example, a through-hole formed in the vicinity of each of the long side surfaces30,31may be used.

The embodiments disclosed above are exemplary in all respects, and should not be considered to limit the disclosure. The scope of the disclosure is defined by the claims, and is intended to cover all equivalents and modifications included within the claims. In addition, numerical values and the like described above are merely exemplary, and the disclosure is not limited to the numerical values and ranges described above.