JP2016143515A - Power storage device and power storage module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device and a power storage module capable of suppressing deformation of a case body.SOLUTION: In a power storage device including an electrode assembly, and a rectangular parallelepiped case 13 for storing the electrode assembly, the case 13 has a case body 16 having an opening of rectangular cross section, and a lid body 17 of rectangular plan view closing the opening. The case body 16 has a bottom wall 18 of rectangular plan view, a pair of first sidewalls 19 standing on a pair of long side edges 18r of the bottom wall 18 so as to face each other, and a pair of second sidewalls 20 standing on a pair of short side edges 18s of the bottom wall 18 so as to face each other in the same direction as the first sidewalls 19. The second sidewalls 20 have a thickness increasing from the end toward the central part thereof.SELECTED DRAWING: Figure 5

Description

  The present invention relates to a power storage device and a power storage device module.

  As a conventional power storage device, for example, a technique described in Patent Document 1 is known. The power storage device described in Patent Literature 1 includes an electrode body and a rectangular parallelepiped case that accommodates the electrode body and the electrolyte. The case includes a bottomed cylindrical main body member having an opening on one surface and a lid member that covers the opening of the main body member.

JP 2013-246878 A

  In the power storage device as in the above prior art, for example, the internal pressure of the case increases due to the generation of gas from the electrolyte, and the stress due to the internal pressure acts on the main body member (case main body), and as a result, the case main body may be deformed. .

  The objective of this invention is providing the electrical storage apparatus and electrical storage apparatus module which can suppress a deformation | transformation of a case main body.

  A power storage device according to one aspect of the present invention is a power storage device including an electrode assembly and a rectangular parallelepiped case that accommodates the electrode assembly, and the case includes a case main body having an opening having a rectangular cross section. The case body is erected so as to be opposed to the bottom wall having a rectangular shape in plan view and a pair of long side edges of the bottom wall. A pair of first side walls, and a pair of second side walls erected on the pair of short side edges of the bottom wall so as to face each other in the same direction as the first side wall, The thickness of is increased from the end of the second side wall toward the center of the second side wall.

  In such a power storage device, stress acts on the case body due to the internal pressure of the case. At this time, the stress acting on the center portion of the second side wall is larger than the stress acting on the end portion of the second side wall. In the present invention, the thickness of the second side wall increases from the end of the second side wall toward the center of the second side wall. For this reason, the intensity | strength of the 2nd side wall with respect to the stress which acts on a 2nd side wall is ensured. Thereby, a deformation | transformation of a 2nd side wall is suppressed.

  The second side wall may be convex toward the inside of the case body. In this case, even if the shape of the outer wall surface of the second side wall is flat, the thickness of the second side wall increases from the end of the second side wall toward the center of the second side wall.

  The inner wall surface of the second side wall may have a cross-sectional mountain shape such that the apex is located at the center of the second side wall. In this case, since the thickness of the central part of the second side wall is ensured, the deformation of the central part of the second side wall is reliably suppressed.

  The inner wall surface of the second side wall may have a cross-sectional mountain shape such that a flat top is located at the center of the second side wall. In this case, when the electrode assembly is accommodated in the case body, the electrode assembly is hardly damaged. Therefore, the accommodation workability of the electrode assembly is improved.

  A power storage device according to another aspect of the present invention is a power storage device including an electrode assembly and a rectangular parallelepiped case that accommodates the electrode assembly, and the case includes a case main body having an opening having a rectangular cross section. And a rectangular lid body that covers and closes the opening, and the case body is erected so as to face the rectangular bottom wall and the pair of long side edges of the bottom wall. A pair of first side walls and a pair of second side walls erected so as to face each other in the same direction as the first side wall at a pair of short side edges of the bottom wall, The thickness of is increased from the end of the bottom wall toward the center of the bottom wall.

  In such a power storage device, stress acts on the case body due to the internal pressure of the case. At this time, the stress acting on the center portion of the bottom wall is larger than the stress acting on the end portion of the bottom wall. In the present invention, the thickness of the bottom wall increases from the end of the bottom wall toward the center of the bottom wall. For this reason, the intensity | strength of the bottom wall with respect to the stress which acts on a bottom wall is ensured. Thereby, deformation of the bottom wall is suppressed.

  The bottom wall may be convex toward the inside of the case body. In this case, even if the shape of the outer wall surface of the bottom wall is planar, the thickness of the bottom wall increases from the end of the bottom wall toward the center of the bottom wall.

  The inner wall surface of the bottom wall may have a cross-sectional mountain shape such that the apex is located at the center of the bottom wall. In this case, since the thickness of the center part of the bottom wall is ensured, the deformation of the center part of the bottom wall is reliably suppressed.

  The inner wall surface of the bottom wall may have a cross-sectional mountain shape such that a flat top is located at the center of the bottom wall. In this case, when the electrode assembly is accommodated in the case body, the electrode assembly is hardly damaged. Therefore, the accommodation workability of the electrode assembly is improved.

  The thickness of the first side wall may increase from the end of the first side wall toward the center of the first side wall. In this case, even if the stress acting on the central portion of the first side wall is larger than the stress acting on the end portion of the first side wall, the strength of the first side wall against the stress acting on the first side wall is ensured. Thereby, a deformation | transformation of a 1st side wall is suppressed.

  A power storage device module according to another aspect of the present invention includes the plurality of power storage devices described above, a plurality of holders that respectively hold the plurality of power storage devices, and a pair of restraining members that restrain the plurality of power storage devices from both sides. The plurality of power storage devices are arranged so that the first side walls face each other, and the pair of restraining members restrains the plurality of power storage devices from both sides in the arrangement direction of the power storage devices. Features.

  In such a power storage device module, stress acts on the case body due to the internal pressure of the case of the power storage device. At this time, the stress acting on the central portion of the wall constituting the case main body is larger than the stress acting on the end portion of the wall. In the present invention, the thickness of the wall increases from the end of the wall toward the center of the wall. For this reason, the intensity | strength of the wall with respect to the stress which acts on a wall is ensured. Thereby, a deformation | transformation of a case main body is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage apparatus and electrical storage apparatus module which can suppress a deformation | transformation of a case main body are provided.

It is an upper side top view which shows a battery module as an electrical storage apparatus module of one Embodiment. FIG. 2 is an exploded perspective view of the battery module shown in FIG. 1. FIG. 3 is a perspective view of the secondary battery shown in FIG. 2. FIG. 4 is an exploded perspective view of the case shown in FIG. 3. It is the sectional view on the AA line of FIG. 4, and the BB sectional view. It is sectional drawing which shows the modification of the case shown by FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

  FIG. 1 is a top plan view showing a battery module as a power storage device module of one embodiment, and FIG. 2 is an exploded perspective view of the battery module shown in FIG. In each figure, the battery module 1 of the present embodiment is disposed on both sides of the battery unit group 3 composed of a plurality (here, seven) of battery units 2 arranged in one direction. And a pair of end plates 4.

  Between one end plate 4 and the battery unit group 3, a shock absorbing rubber member 5 and an intermediate plate 6 are arranged side by side in the arrangement direction of the battery units 2. The end plate 4 is a restraining member that restrains the plurality of battery units 2 from both sides with respect to the arrangement direction of the battery units 2 by a plurality of sets (four sets in this case) of bolts 7 and nuts 8. The end plate 4 is made of a highly rigid metal (for example, iron).

  The battery unit 2 includes a secondary battery 10 as a power storage device and a holder 11 that holds the secondary battery 10. The secondary battery 10 of this embodiment is a lithium ion secondary battery.

  As shown in FIG. 3, the secondary battery 10 includes an electrode assembly 12, a rectangular parallelepiped case 13 that accommodates the electrode assembly 12, and a positive terminal 14 and a negative terminal 15 that are attached to the case 13. It has. The case 13 is filled with an electrolytic solution (not shown). In addition, the rectangular parallelepiped shape here includes not only a complete rectangular parallelepiped shape but also a substantially rectangular parallelepiped shape.

  Although not specifically shown, the electrode assembly 12 includes a positive electrode sheet containing a positive electrode active material, a negative electrode sheet containing a negative electrode active material, and a separator sandwiched between the positive electrode sheet and the negative electrode sheet. It is composed of A plurality of positive electrode sheets, negative electrode sheets, and separators are laminated.

  The case 13 is made of metal (for example, aluminum). As shown in FIGS. 3 and 4, the case 13 includes a bottomed rectangular tube-shaped case body 16 having an opening 16 a having a rectangular cross section on the upper surface, and a plan view covering and covering the opening 16 a of the case body 16. And a rectangular lid 17. The case body 16 and the lid body 17 are joined by welding. The rectangular shape here includes not only a complete rectangular shape but also a substantially rectangular shape.

  5A is a cross-sectional view taken along line AA in FIG. 4, and FIG. 5B is a cross-sectional view taken along line BB in FIG. In FIG. 5, the case main body 16 includes a bottom wall 18 having a rectangular shape in plan view, and a pair of first side walls 19 erected so as to face a pair of long side edges 18 r of the bottom wall 18. The pair of short side edges 18 s of the bottom wall 18 have a pair of second side walls 20 erected so as to face each other in the same direction as the first side wall 19. The long side edge 18 r of the bottom wall 18 is an edge along the long side of the bottom wall 18. The short side edge 18 s of the bottom wall 18 is an edge along the short side of the bottom wall 18. The first side wall 19 is connected to the long side edge 18 r of the bottom wall 18. The second side wall 20 is connected to the short side edge 18 s of the bottom wall 18 and both side ends of the first side wall 19.

  The bottom wall 18 is convex toward the inside of the case body 16. Specifically, the inner wall surface 18 a of the bottom wall 18 has a cross-sectional mountain shape (a triangular cross-section) such that the vertex 18 b is located at the center of the bottom wall 18. Here, the central portion of the bottom wall 18 is a central portion in two directions perpendicular to the thickness direction of the bottom wall 18. The outer wall surface 18c of the bottom wall 18 constituting the bottom surface of the case body 16 has a flat shape.

  Accordingly, the thickness of the bottom wall 18 continuously increases from the end (edge) of the bottom wall 18 toward the center of the bottom wall 18. The thickness (minimum thickness) of the end portion of the bottom wall 18 is, for example, 2.0 mm, and the thickness (maximum thickness) of the central portion of the bottom wall 18 is, for example, 3.0 mm. The ratio of the minimum thickness and the maximum thickness of the bottom wall 18 is, for example, 1.1 to 2.0.

  Each first side wall 19 is convex toward the inside of the case body 16. Specifically, the inner wall surface 19 a of the first side wall 19 has a cross-sectional mountain shape (a triangular cross section) such that the apex 19 b is located at the center of the first side wall 19. Here, the central part of the first side wall 19 is a central part in two directions perpendicular to the thickness direction of the first side wall 19. The outer wall surface 19c of each first side wall 19 constituting one side surface of the case body 16 facing each other has a planar shape.

  As a result, the thickness of the first side wall 19 continuously increases from the end (edge) of the first side wall 19 toward the center of the first side wall 19. The thickness of the first side wall 19 may be the same as the thickness of the bottom wall 18 or may be different from the thickness of the bottom wall 18.

  Each second side wall 20 is convex toward the inside of the case body 16. Specifically, the inner wall surface 20 a of the second side wall 20 has a cross-sectional mountain shape (triangular cross-sectional shape) such that the vertex 20 b is located at the center of the second side wall 20. Here, the central part of the second side wall 20 is a central part in two directions perpendicular to the thickness direction of the second side wall 20. The outer wall surface 20c of each second side wall 20 constituting the other side surface of the case body 16 facing each other has a planar shape.

  Thereby, the thickness of the second side wall 20 continuously increases from the end (edge) of the second side wall 20 toward the center of the second side wall 20. The thickness of the second side wall 20 may be the same as the thickness of the bottom wall 18 or may be different from the thickness of the bottom wall 18.

  In such a case body 16, for example, the bottom wall 18, the first side wall 19 and the second side wall 20 are separately formed, and then the first side wall 19 and the second side wall 20 are welded to the bottom wall 18 and the first side wall 19. And the second side wall 20 are welded.

  The lid body 17 is composed of a flat plate having the same overall thickness. The thickness of the lid 17 is, for example, 2.0 mm. Two through holes 17 a for attaching the positive electrode terminal 14 and the negative electrode terminal 15 are formed in the lid body 17. An end (edge) of the lid body 17 is connected to the first side wall 19 and the second side wall 20.

  Returning to FIGS. 1 to 3, the positive electrode terminal 14 and the negative electrode terminal 15 are terminals for taking out the electric power of the electrode assembly 12 to the outside. The positive electrode terminal 14 and the negative electrode terminal 15 are attached to the lid body 17 in an electrically insulated state. The positive electrode terminal 14 is electrically connected to the positive electrode sheet of the electrode assembly 12. The negative electrode terminal 15 is electrically connected to the negative electrode sheet of the electrode assembly 12.

  The holder 11 that holds the secondary battery 10 is a frame-shaped member that is integrally formed of resin. The holder 11 includes a base portion 21 on which the secondary battery 10 is placed, a pair of side portions 22 that sandwich the secondary battery 10 with respect to the opposing direction of the second side walls 20 of the case body 16, and the secondary battery 10. And a wiring portion 23 that covers a part of the lid body 17 (a portion excluding the positive electrode terminal 14 and the negative electrode terminal 15 and the central portion of the lid body 17). The surface of the base 21 on which the secondary battery 10 is placed and the surface of the side 22 facing the second side wall 20 of the case body 16 of the secondary battery 10 are both flat.

  The wiring portion 23 is provided with a plurality (two in this case) of bolt guide portions 24 having bolt insertion holes 24a through which the screw portions of the bolts 7 are inserted. A bolt guide portion 25 having a bolt insertion hole 25a through which the screw portion of the bolt 7 is inserted is provided at each lower corner portion of the holder 11.

  The plurality of secondary batteries 10 are arranged so that the first side walls 19 of each case body 16 face each other with the heat transfer plate 26 and the double-sided adhesive tape 27 interposed therebetween. Two adjacent secondary batteries 10 are arranged such that the positive electrode terminal 14 and the negative electrode terminal 15 are opposite to each other. Then, the positive electrode terminals 14 and the negative electrode terminals 15 of two adjacent secondary batteries 10 are connected to each other via a bus bar 28. Each secondary battery 10 is restrained from both sides with respect to the arrangement direction of the secondary batteries 10 by a pair of end plates 4.

  In the battery module 1 configured as described above, when hydrogen gas is generated from the electrolyte filled in the case 13 of the secondary battery 10, the internal pressure of the case 13 increases. Moreover, even if the active material provided in the positive electrode sheet and the negative electrode sheet of the secondary battery 10 expands and contracts, the internal pressure of the case 13 increases. When the internal pressure of the case 13 increases, stress due to the internal pressure is applied to the case 13.

  At this time, the end of the bottom wall 18 of the case main body 16 is connected to the first side wall 19 and the second side wall 20 of the case main body 16, but the central part of the bottom wall 18 is the first side wall 19 and the second side wall. 20 away. Accordingly, since the stress applied to the center portion of the bottom wall 18 is greater than the stress applied to the end portion of the bottom wall 18, the center portion of the bottom wall 18 is more easily deformed than the end portion of the bottom wall 18. Further, the end portion of the first side wall 19 is connected to the bottom wall 18, the second side wall 20 and the lid body 17, but the central portion of the first side wall 19 is the bottom wall 18, the second side wall 20 and the lid body 17. Away from. Accordingly, since the stress applied to the central portion of the first side wall 19 is greater than the stress applied to the end portion of the first side wall 19, the central portion of the first side wall 19 is more easily deformed than the end portion of the first side wall 19. The end of the second side wall 20 is connected to the bottom wall 18, the first side wall 19, and the lid body 17, but the central portion of the second side wall 20 is the bottom wall 18, the first side wall 19, and the lid body 17. Away from. Therefore, since the stress applied to the central portion of the second side wall 20 is greater than the stress applied to the end portion of the second side wall 20, the central portion of the second side wall 20 is more easily deformed than the end portion of the second side wall 20.

  However, each secondary battery 10 is restrained in the arrangement direction of the secondary batteries 10 by a pair of end plates 4. For this reason, the first side walls 19 of the case body 16 of each secondary battery 10 are restrained from each other. On the other hand, the bottom wall 18 and the second side wall 20 of the case body 16 only come into contact with the base portion 21 and the side portion 22 of the resin holder 11, respectively. Therefore, the bottom wall 18 and the second side wall 20 are more easily deformed than the first side wall 19.

  On the other hand, in the present embodiment, the thickness of the second side wall 20 increases from the end of the second side wall 20 toward the center of the second side wall 20. Therefore, since the strength of the second side wall 20 against the stress acting on the second side wall 20 by the internal pressure of the case 13 is ensured, deformation of the second side wall 20 due to the stress acting on the second side wall 20 can be suppressed. As a result, deformation of the side portion 22 of the holder 11 can be suppressed.

  Further, since the second side wall 20 is convex toward the inside of the case body 16, as described above, even if the shape of the outer wall surface 20c of the second side wall 20 is planar, the second side wall 20 The thickness increases from the end of the second side wall 20 toward the center of the second side wall 20. At this time, since the shape of the outer wall surface 20c of the second side wall 20 is flat, the surface facing the second side wall 20 in the side portion 22 of the holder 11 is changed to the shape of the outer wall surface 20c of the second side wall 20. There is no need to process them together.

  Further, the inner wall surface 20 a of the second side wall 20 has a cross-sectional mountain shape such that the vertex 20 b is located at the center of the second side wall 20. Therefore, since the thickness of the center part of the 2nd side wall 20 is ensured, the deformation | transformation of the center part of the 2nd side wall 20 by the stress which acts on the 2nd side wall 20 can be suppressed reliably.

  Further, in the present embodiment, the thickness of the bottom wall 18 increases from the end of the bottom wall 18 toward the center of the bottom wall 18. Accordingly, the strength of the bottom wall 18 against the stress acting on the bottom wall 18 due to the internal pressure of the case 13 is ensured, so that deformation of the bottom wall 18 due to the stress acting on the bottom wall 18 can be suppressed. As a result, deformation of the base 21 of the holder 11 can be suppressed.

  Further, since the bottom wall 18 is convex toward the inside of the case main body 16, even if the shape of the outer wall surface 18c of the bottom wall 18 is flat as described above, the thickness of the bottom wall 18 is small. The distance increases from the end of the bottom wall 18 toward the center of the bottom wall 18. At this time, since the shape of the outer wall surface 18 c of the bottom wall 18 is a flat shape, the surface on which the case 13 is placed on the base portion 21 of the holder 11 is processed according to the shape of the outer wall surface 18 c of the bottom wall 18. You don't have to.

  Further, the inner wall surface 18 a of the bottom wall 18 has a cross-sectional mountain shape in which the vertex 18 b is located at the center of the bottom wall 18. Therefore, since the thickness of the center part of the bottom wall 18 is ensured, the deformation | transformation of the center part of the bottom wall 18 by the stress which acts on the bottom wall 18 can be suppressed reliably.

  Further, the thickness of the first side wall 19 increases from the end of the first side wall 19 toward the center of the first side wall 19. Therefore, since the strength of the first side wall 19 against the stress acting on the first side wall 19 is ensured by the internal pressure of the case 30, deformation of the first side wall 19 due to the stress acting on the first side wall 19 can be suppressed.

  As described above, according to the present embodiment, the deformation of the case body 16 can be prevented. Further, as compared with the case where the bottom wall 18, the first side wall 19, and the second side wall 20 constituting the case body 16 are generally thickened from the end to the center, the electrode assembly 12 is accommodated and the electrolyte ( The internal space of the case 13 filled with (not shown) can be widened. Thereby, the capacity of the battery module 1 can be increased.

  FIG. 6 is a cross-sectional view showing a modification of the case 13 shown in FIG. 5, and corresponds to FIG. In FIG. 6, the inner wall surface 18 a of the bottom wall 18 has a cross-sectional mountain shape (cross-sectional trapezoidal shape) such that a planar top portion 18 d is located at the center of the bottom wall 18. Accordingly, the thickness of the bottom wall 18 continuously increases from the end (edge) of the bottom wall 18 toward the center of the bottom wall 18.

  The inner wall surface 19 a of the first side wall 19 has a cross-sectional mountain shape (cross-sectional trapezoidal shape) such that a planar top portion 19 d is located at the center of the first side wall 19. As a result, the thickness of the first side wall 19 continuously increases from the end (edge) of the first side wall 19 toward the center of the first side wall 19.

  The inner wall surface 20 a of the second side wall 20 has a cross-sectional mountain shape (cross-sectional trapezoidal shape) such that a planar top 20 d is located at the center of the second side wall 20. Thereby, the thickness of the second side wall 20 continuously increases from the end (edge) of the second side wall 20 toward the center of the second side wall 20.

  In this modification, the electrode assembly 12 is not easily damaged when the electrode assembly 12 is accommodated in the case body 16. Accordingly, the workability of accommodating the electrode assembly 12 can be improved.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the inner wall surface 18 a of the bottom wall 18 has a cross-sectional mountain shape such that the vertex 18 b is located at the center of the bottom wall 18, or a flat top at the center of the bottom wall 18. The bottom wall 18 is convex so that the thickness of the bottom wall 18 increases from the end of the bottom wall 18 toward the center of the bottom wall 18. If it is, the shape of the inner wall surface 18a of the bottom wall 18 is not particularly limited thereto, and may be, for example, a curved cross section. Similarly, the shape of the inner wall surface 19a of the first side wall 19 and the inner wall surface 20a of the second side wall 20 may be, for example, a curved cross section.

  Moreover, in the said embodiment, although the thickness of the bottom wall 18 is continuously large toward the center part of the bottom wall 18 from the edge part of the bottom wall 18, it is not restricted to the form in particular, The bottom wall 18 The thickness of the bottom wall 18 may increase stepwise from the end of the bottom wall 18 toward the center of the bottom wall 18. Similarly, the thickness of the first side wall 19 may increase stepwise from the end of the first side wall 19 toward the center of the first side wall 19, and the thickness of the second side wall 20 may increase. It may increase in steps from the end of 20 toward the center of the second side wall 20.

  Moreover, in the said embodiment, although the bottom wall 18 is convex toward the inner side of the case main body 16, it is not restricted to the form in particular, The bottom wall 18 is convex toward the outer side of the case main body 16. It may be. Similarly, the first side wall 19 and the second side wall 20 may be convex toward the outside of the case body 16. In this case, it becomes easy to accommodate the electrode assembly 12 in the case body 16 while widening the internal space of the case 13.

  Furthermore, in the above embodiment, the thickness of the bottom wall 18 increases from the end of the bottom wall 18 toward the center of the bottom wall 18, and the thickness of the first side wall 19 increases from the end of the first side wall 19. The thickness of the second side wall 20 increases from the end of the second side wall 20 toward the center of the second side wall 20, but the shape is not particularly limited. However, at least the thickness of the bottom wall 18 increases from the end of the bottom wall 18 toward the center of the bottom wall 18, or at least the thickness of the second side wall 20 increases from the end of the second side wall 20. What is necessary is just to become large toward the center part of 2 side walls 20. At this time, the combination of the convex shape of the bottom wall 18 and the convex shape of the second side wall 20 can be changed as appropriate. For example, the convex shape of the bottom wall 18 may be a cross-sectional mountain shape, the convex shape of the second side wall 20 may be a cross-sectional curved shape, the convex shape of the bottom wall 18 may be a cross-sectional curved shape, and the convex shape of the second side wall 20 may be It is good also as a cross-sectional mountain shape.

  In the above embodiment, the thickness of the lid body 17 is generally the same, but the thickness is not particularly limited, and the thickness of the lid body 17 is from the end of the lid body 17 to the center of the lid body 17. You may become large toward the part. Note that the thickness of the lid body 17 may be the same as the thickness of the case body 16 or may be different from the thickness of the case body 16.

  Furthermore, in the above embodiment, the power storage device is the secondary battery 10 such as a lithium ion secondary battery. However, the power storage device of the present invention is not particularly limited to the secondary battery, for example, an electric double layer capacitor or a lithium ion capacitor. The present invention can also be applied.

DESCRIPTION OF SYMBOLS 1 ... Battery module (electric storage apparatus module), 4 ... End plate (restraint member), 10 ... Secondary battery (electric storage apparatus), 11 ... Holder, 12 ... Electrode assembly, 13 ... Case, 16 ... Case main body, 16a ... Opening portion, 17 ... lid, 18 ... bottom wall, 18a ... inner wall surface, 18b ... apex, 18d ... top portion, 18r ... long edge portion, 18s ... short edge portion, 19 ... first side wall, 19a ... inner wall surface 19b ... apex, 19d ... top, 20 ... second side wall, 20a ... inner wall, 20b ... apex, 20d ... top.

Claims (10)

A power storage device comprising an electrode assembly and a rectangular parallelepiped case that accommodates the electrode assembly,
The case includes a case main body having an opening with a rectangular cross section, and a rectangular lid body that covers and covers the opening.
The case body includes a bottom wall having a rectangular shape in plan view, a pair of first side walls erected so as to face a pair of long side edges of the bottom wall, and a pair of bottom walls. A pair of second side walls erected so as to face each other in the same direction as the first side wall at the short edge,
The thickness of the said 2nd side wall is large toward the center part of the said 2nd side wall from the edge part of the said 2nd side wall, The electrical storage apparatus characterized by the above-mentioned.   The power storage device according to claim 1, wherein the second side wall is convex toward the inside of the case body.   3. The power storage device according to claim 2, wherein the inner wall surface of the second side wall has a mountain-shaped cross section in which a vertex is located at a central portion of the second side wall.   3. The power storage device according to claim 2, wherein an inner wall surface of the second side wall has a cross-sectional mountain shape such that a flat top is located at a central portion of the second side wall. A power storage device comprising an electrode assembly and a rectangular parallelepiped case that accommodates the electrode assembly,
The case includes a case main body having an opening with a rectangular cross section, and a rectangular lid body that covers and covers the opening.
The case body includes a bottom wall having a rectangular shape in plan view, a pair of first side walls erected so as to face a pair of long side edges of the bottom wall, and a pair of bottom walls. A pair of second side walls erected so as to face each other in the same direction as the first side wall at the short edge,
The thickness of the said bottom wall is large toward the center part of the said bottom wall from the edge part of the said bottom wall, The electrical storage apparatus characterized by the above-mentioned.   The power storage device according to claim 5, wherein the bottom wall is convex toward the inside of the case body.   The power storage device according to claim 6, wherein the inner wall surface of the bottom wall has a cross-sectional mountain shape in which a vertex is located at a central portion of the bottom wall.   The power storage device according to claim 6, wherein the inner wall surface of the bottom wall has a cross-sectional mountain shape in which a flat top portion is located at a central portion of the bottom wall.   9. The power storage device according to claim 1, wherein a thickness of the first side wall increases from an end portion of the first side wall toward a central portion of the first side wall. 10. . A plurality of power storage devices according to claim 1;
A plurality of holders each holding the plurality of power storage devices;
A pair of restraining members that restrain the plurality of power storage devices from both sides,
The plurality of power storage devices are arranged so that the first side walls face each other,
The pair of restraining members restrains the plurality of power storage devices from both sides with respect to the arrangement direction of the power storage devices.

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