Power storage device and power storage module

Abstract

This power storage device is provided with: an electrode body in which a positive electrode plate and a negative electrode plate are layered with a separator therebetween; an outer can which houses the electrode body and an electrolyte, and has a cylindrical side wall part and an opening part formed at at least one end of the side wall part; and a sealing plate which closes the opening part of the outer can. A joint part where the peripheral edge of the sealing plate and the opening part are joined is formed, and a thin-walled part extending in a width direction is formed in each of a pair of long walls facing each other in the depth direction of the side wall part.

Description

Technical Field

[0001] The present disclosure relates to a power storage device and a power storage module.

Background Art

[0002] Conventionally, as one type of power storage device, for example, as disclosed in Patent Document 1, a power storage device in which a sealing plate is welded to an opening of an exterior can is disclosed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] The power storage device may expand due to various factors such as aging deterioration of the electrode body, expansion or contraction of the electrode body. As described above, when the power storage device in which the sealing plate and the opening of the exterior can are joined expands, mechanical stress is likely to be applied to the periphery of the side surface of the exterior can. At this time, one end of the side wall constitutes the opening. Therefore, there is a possibility that mechanical stress is also applied to the joint portion between the opening and the sealing plate. If excessive stress occurs in this joint portion, there is also a possibility that the joint portion breaks.

[0005] An object of the present disclosure is to provide a power storage device and a power storage module with excellent reliability.

Means for Solving the Problems

[0006] A power storage device according to one aspect of the present disclosure includes an electrode body in which a positive electrode plate and a negative electrode plate are stacked via a separator, an exterior can that houses the electrode body and an electrolytic solution and has a cylindrical side wall portion and an opening formed at at least one end of the side wall portion, and a sealing plate that closes the opening of the exterior can. A joint portion is formed where the periphery of the sealing plate and the opening are joined, and thin portions extending in a second direction orthogonal to the first direction are formed on a pair of side walls facing each other in the first direction of the side wall portion.

Advantages of the Invention

[0007] According to one aspect of the present disclosure, when the power storage device bulges, the thin portions formed on the exterior can deform preferentially, thereby reducing the mechanical stress generated at the joint portion between the exterior can and the sealing plate. As a result, the reliability of the power storage device can be improved.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

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Figure 8

Figure 9

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The shapes, materials, and numbers described below are examples for explanation and can be appropriately changed according to the specifications of the power storage device or power storage module. In the following, the same reference numerals will be assigned to equivalent elements in all the drawings for explanation.

[0010] Using FIG. 1, a power storage device 10 which is an example of an embodiment will be described. FIG. 1 is a cross-sectional view showing the power storage device 10.

[0011] A power storage device 10 which is an example of an embodiment is a non-aqueous electrolyte secondary battery, and a preferred example is a lithium-ion battery. Note that the power storage device 10 may also be a nickel-metal hydride battery, an electric double layer capacitor, or the like. The power storage device 10 is used, for example, as a driving power source for an electric vehicle or a hybrid vehicle, or as a stationary power storage system for peak shifting of grid power. The power storage device 10 includes an electrode body 20 in which a positive electrode plate and a negative electrode plate are laminated with a separator interposed therebetween, an exterior can 30 that houses the electrode body 20 and an electrolytic solution, and a sealing plate 40 that closes an opening 30H of the exterior can 30.

[0012] Hereinafter, for convenience of explanation, the direction in which the sealing plate 40 side of the exterior can 30 is the upper side and the side opposite to the sealing plate 40 is the lower side will be defined as the height direction, the direction in which the positive electrode terminal 41 and the negative electrode terminal 42 are arranged will be defined as the width direction as the second direction, and the direction orthogonal to the height direction and the width direction will be defined as the depth direction as the first direction (see FIG. 3) for explanation.

[0013] The electrode body 20 is formed by laminating a substantially rectangular sheet-shaped positive electrode plate, a negative electrode plate, and a separator. The laminated positive electrode plate, negative electrode plate, and separator may be constrained using a fixing tape, or the positive electrode plate or negative electrode plate may be adhered and fixed to the separator by applying an adhesive to the surface of the separator facing the positive electrode plate or negative electrode plate. Further, the electrode body 20 is housed in an insulating holder 29 having a substantially rectangular parallelepiped shape with a bottom and an open upper end. The electrode body 20 is disposed in the outer can 30 such that the lamination direction in which the positive electrode plate and the negative electrode plate are laminated is parallel to the depth direction of the outer can 30. Note that the electrode body 20 may be formed by winding a strip-shaped positive electrode plate and a strip-shaped negative electrode plate with a strip-shaped separator interposed therebetween to form a wound body, and then flattening this wound body to form a flat wound body. At this time, the lamination direction of the electrode body 20 may be the thickness direction of the flat wound body.

[0014] The positive electrode plate has, for example, a core made of an aluminum foil with a thickness of 15 μm, electrode layers formed on the front and back surfaces of the core, a core exposed portion where no electrode layer is formed on the core, and a positive electrode lead 21 that is a part of the core exposed portion and extends from the upper end of the core exposed portion.

[0015] The positive electrode layer contains, for example, an active material, a conductive agent, and a binder. As the active material of the positive electrode, a lithium nickel cobalt manganese composite oxide can be used, as the binder, polyvinylidene fluoride (PVdF) can be used, as the conductive agent, a carbon material can be used, and as the dispersion medium, N-methylpyrrolidone (NMP) can be used. When forming the electrode layer, a slurry containing these active material, conductive agent, binder, and dispersant is prepared. This slurry is applied to both sides of the core of the positive electrode. Then, by drying this, the dispersion medium in the slurry is removed, and an electrode layer is formed on the core. Thereafter, the electrode layer is compressed to a predetermined thickness. The positive electrode plate thus obtained is cut into a predetermined shape.

[0016] The negative electrode plate has, for example, a core made of a copper foil with a thickness of 8 μm, electrode layers formed on the front and back surfaces of the core, a core exposed portion where no electrode layer is formed on the core, and a negative electrode lead 22 that is a part of the core exposed portion and extends from the upper end of the core exposed portion.

[0017] The electrode layer of the negative electrode contains, for example, an active material, a conductive agent, a binder, and a thickener. As the active material of the negative electrode, graphite can be used, as the binder styrene-butadiene rubber (SBR), as the thickener carboxymethyl cellulose (CMC), and as the dispersion medium water can be used respectively. When forming the electrode layer, a slurry containing these active material, conductive agent, binder, and thickener is prepared. This slurry is applied to both sides of the core body of the negative electrode. Then, by drying this, the dispersion medium in the slurry is removed, and an electrode layer is formed on the core body. Thereafter, the electrode layer is compressed to a predetermined thickness. The negative electrode plate thus obtained is cut into a predetermined shape.

[0018] As the separator, for example, a resin-made one can be used, and as the resin, polyolefin, polyethylene, or polypropylene can be used.

[0019] The positive electrode lead 21 is electrically connected to the positive electrode terminal 41 provided on the sealing plate 40 via the current collecting member 23. The positive electrode leads 21 are provided in the number corresponding to the number of positive electrode plates constituting the electrode body 20. The plurality of positive electrode leads 21 are respectively joined to the current collecting member 23 in a state of being bundled at the tip side in the extending direction. When joining the positive electrode lead 21 to the current collecting member 23, ultrasonic welding, resistance welding, laser welding, cold pressure welding, etc. can be performed for joining.

[0020] The negative electrode lead 22 is electrically connected to the negative electrode terminal 42 provided on the sealing plate 40 via the current collecting member 24. The negative electrode leads 22 are provided in the number corresponding to the number of negative electrode plates constituting the electrode body 20. The plurality of negative electrode leads 22 are respectively joined to the current collecting member 24 in a state of being bundled at the tip side in the extending direction. When joining each negative electrode lead 22 to the current collecting member 24, ultrasonic welding, resistance welding, laser welding, cold pressure welding, etc. can be performed for joining.

[0021] The current collector member 23 of the positive electrode is composed of, for example, a plate material made of aluminum. The current collector member 23 is connected to the positive electrode lead 21 at one end and to the positive electrode terminal 41 at the other end. An insulating member 25 is interposed between the current collector member 23 and the sealing plate 40.

[0022] The positive electrode terminal 41 and the current collector member 23 may be electrically connected via a current interruption device (CID). This CID is a safety device that can cut off the electrical connection between the current collector member 23 and the positive electrode terminal 41 when gas is generated inside the outer can 30 during an abnormality of the power storage device 10 and the pressure inside the outer can 30 exceeds a predetermined pressure. The CID has, for example, an inversion plate that is connected to the other end of the current collector member 23 and deforms in a direction away from the current collector member 23 when receiving the pressure inside the outer can 30, and a conductive cap that electrically connects the inversion plate and the positive electrode terminal 41. The conductive cap is a dish-shaped conductive member with an opening located on the lower side (the side of the electrode body 20) and an upper surface located on the upper side (the side of the sealing plate 40). A connection hole is formed in the upper surface, and the positive electrode terminal 41 is inserted therein.

[0023] The current collector member 24 of the negative electrode is composed of, for example, a plate material made of copper. The current collector member 24 is connected to the negative electrode lead 22 at one end and to the negative electrode terminal 42 at the other end. An insulating member 26 is interposed between the current collector member 24 and the sealing plate 40.

[0024] The outer can 30 is, for example, a rectangular case having a bottom 30B, a rectangular tube-shaped side wall portion erected from the periphery of the bottom 30B, and an opening 30H formed at an end opposite to the bottom 30B. The outer can 30 is made of, for example, a metal such as aluminum. The outer can 30 can be formed by, for example, drawing an aluminum material. Each cylindrical side wall portion is composed of two long walls 30X formed to face each other in the depth direction and two short walls 30Y formed to face each other in the width direction. A thin portion 30J, which will be described in detail later, is formed in the long wall 30X (see FIGS. 2 and 3).

[0025] On the sealing plate 40, the positive electrode terminal 41 and the negative electrode terminal 42 are arranged apart from each other in the longitudinal direction of the sealing plate 40 (the width direction in FIG. 1). The positive electrode terminal 41 and the negative electrode terminal 42 protrude from the top surface of the sealing plate 40. The sealing plate 40 is formed, for example, by processing an aluminum plate. The sealing plate 40 is located on the opening 30H of the outer can 30, and the sealing plate 40 can be welded to the open end of the outer can 30 using, for example, a laser or the like to seal the inside of the outer can 30.

[0026] The sealing plate 40 may have a liquid injection hole for injecting the electrolytic solution into the outer can 30. A liquid injection plug for closing the liquid injection hole may be provided on the sealing plate 40. Further, the sealing plate 40 may be configured by being surrounded by a plurality of linear grooves, and a pressure regulating valve 45 may be provided that tears the grooves when the pressure inside the outer can 30 exceeds a predetermined pressure to exhaust the gas inside the outer can 30 to the outside. Further, it is preferable to form an annular groove along the periphery on the top surface of the sealing plate 40. With this configuration, when welding and joining the sealing plate 40 and the opening 30H of the outer can 30, the periphery of the sealing plate 40 can be efficiently melted.

[0027] The positive electrode terminal 41 is provided through a terminal hole of the sealing plate 40, one end is exposed to the outside of the outer can 30, and the other end is accommodated inside the outer can 30. In the positive electrode terminal 41, the other end is inserted into a connection hole provided on the upper surface of the conductive cap, and the other end of the positive electrode terminal 41 is caulked so as to spread in the radial direction and is fixed to the conductive cap. The positive electrode terminal 41 is composed of, for example, an aluminum column or cylinder.

[0028] The negative electrode terminal 42 is provided through a terminal hole of the sealing plate 40, one end is exposed to the outside of the outer can 30, and the other end is accommodated inside the outer can 30. The negative electrode terminal 42 may be composed of, for example, a clad material in which the other end connected to the current collecting member 24 inside the outer can 30 is made of a copper material and one end exposed to the outside of the outer can 30 is made of aluminum. At the other end, the negative electrode terminal 42 is caulked so as to spread in the radial direction and is fixed to the sealing plate 40 together with the current collecting member 24.

[0029] With reference to FIGS. 2 and 3, the exterior can 30 will be described in detail. FIG. 2 is a front view of the power storage device 10. FIG. 3 is a cross-sectional view taken along line AA of FIG. 2.

[0030] As illustrated in FIGS. 2 and 3, in a long wall 30X of the exterior can 30 which is an example of an embodiment, a thin portion 30J is formed along the width direction. According to the thin portion 30J, although details will be described later, when the power storage device 10 swells, mechanical stress generated at the joint between the exterior can 30 and the sealing plate 40 can be reduced. Thereby, the reliability of the power storage device 10 can be improved.

[0031] The thin portion 30J is formed below the joint between the exterior can 30 and the sealing plate 40. In other words, the thin portion 30J is formed below the sealing plate 40 in the height direction of the long wall 30X of the exterior can 30. Further, the thin portion 30J is formed above the electrode body 20 housed in the height direction of the long wall 30X of the exterior can 30. In other words, the thin portion 30J is not formed at the same position as the electrode body 20 housed in the height direction of the long wall 30X of the exterior can 30.

[0032] Here, by forming the thin portion 30J below the sealing plate 40 and above the electrode body 20, for example, when the power storage device 10 swells and the long wall 30X deforms into an arc shape that bulges outward, in the long wall 30X, the region excluding the upper side of the thin portion 30J including the joint with the sealing plate 40 can be preferentially bent (deformed).

[0033] Further, by not forming the thin portion 30J at the same position as the electrode body 20 housed in the height direction, for example, when the long wall 30X of the exterior can 30 is pressed from the outside by a holding member or the like in the power storage device 10, a pressing force can be uniformly applied to the electrode body 20. This is because when a region of the thin portion and a region where the thin portion is not formed coexist in the pressing region, the ease of deformation is different in each region, and the stress transmitted to the electrode body through each region is likely to be different.

[0034] The thin-walled portion 30J is formed on the outer surface of each long wall 30X of the outer can 30 so that the surface is concave. The rising edge of the concave step portion of the thin-walled portion 30J forms a gentle slope with respect to the surface of the long wall 30X. This gentle slope means that the thin-walled portion 30J has an inner bottom surface and an inner side surface erected from this inner bottom surface, this inner side surface corresponds to the above slope, and the angle formed by this slope and the inner bottom surface is 90° or more. This angle may be 135° or more. The connection portion between the bottom surface and the slope of the thin-walled portion 30J by this slope can suppress stress concentration when the long wall 30X deforms. Thereby, it is possible to make it difficult to break at the thin-walled portion 30J when the outer can 30 bulges. Further, although details will be described later in other examples of the embodiment, the thin-walled portion 30J may be formed to be concave on the inner surface of each long wall 30X of the outer can 30. Further, the thin-walled portion 30J may be formed to be concave on both the outer surface and the inner surface of each long wall 30X of the outer can 30. Furthermore, the rising edge of the concave step portion of the thin-walled portion 30J may be perpendicular to the surface of the long wall 30X.

[0035] The thin-walled portion 30J is formed such that the size in the width direction of the thin-walled portion 30J is smaller than the size in the width direction of the long wall 30X. More specifically, the thin-walled portion 30J is formed so as not to reach the corner where the short wall 30Y is formed in the width direction of the long wall 30X. Further, the thin-walled portion 30J is formed such that the center position in the width direction of the thin-walled portion 30J and the center position in the width direction of the long wall 30X are substantially the same position in the width direction.

[0036] In the width direction, when the thin-walled portion 30J has a central portion and an end portion, the size in the height direction of this central portion is formed to be larger than the size in the height direction of the end portion. More specifically, the shape of the opening edge of the thin-walled portion 30J is an arc shape in which the upper step portion of the thin-walled portion 30J (specifically, the start position and the end position of the step portion) bulges upward when viewed from the depth direction, and the lower step portion of the thin-walled portion 30J (specifically, the start position and the end position of the step portion) is an arc shape that bulges downward when viewed from the depth direction.

[0037] Here, in the outer can 30, both end portions in the width direction of the long wall 30X are close to the corner portions of the outer can 30 and have high rigidity. Therefore, for example, when the power storage device 10 bulges, the central portion in the width direction of the long wall 30X deforms more greatly compared to both end portions in the width direction of the long wall 30X. Thus, by making the size in the height direction of the central portion in the width direction of the thin-walled portion 30J larger than the size in the height direction of both end portions in the width direction of the thin-walled portion 30J, when the power storage device 10 bulges, it is possible to suppress the load on the central portion of the joint portion in the width direction where the deformation becomes large. Further, it is considered that the same effect can be obtained even if the depth of the indentation of the central portion of the thin-walled portion in the width direction is larger than the depth of the indentation of the end portion of the thin-walled portion in the width direction instead of the size in the height direction.

[0038] Using FIG. 4, the effect of the power storage device 10 in which the thin-walled portion 30J is formed will be described.

[0039] The power storage device 10 may bulge due to various factors such as the aging deterioration of the power storage device 10, the expansion or contraction of the electrode body 20, or the like. When the power storage device 10 in which the sealing plate 40 and the opening 30H of the outer can 30 are joined by welding bulges, mechanical stress is likely to be applied to the joint portion. If excessive stress occurs in the joint portion, there is also a risk that the joint portion will break.

[0040] As illustrated in FIG. 4, according to the power storage device 10 which is an example of the present embodiment, when the power storage device 10 bulges, the long wall 30X deforms in an arc shape that bulges outward so that the thin-walled portion 30J of the long wall 30X bends greatly. On the other hand, in the long wall 30X above the thin-walled portion 30J of the outer can 30, the amount of deformation is reduced, and the mechanical stress generated in the joint portion can be reduced. As a result, breakage of the joint portion is suppressed, and the reliability of the power storage device 10 can be improved.

[0041] Using FIG. 5, the outer can 30 which is another example of the present embodiment will be described. FIG. 5 is a cross-sectional view corresponding to the AA cross-section of FIG. 2.

[0042] As illustrated in FIG. 5, in another example of the present embodiment, a thin portion 30K is formed along the width direction on the long wall 30X of the outer can 30. The thin portion 30K is formed on the inner surface of each long wall 30X of the outer can 30 such that the surface is concave. The thin portion 30K is the same as the above-described thin portion 30J except that it is formed inside each long wall 30X of the outer can 30. Therefore, the thin portion 30K exhibits substantially the same effects as the effects of the above-described thin portion 30J.

[0043] Further, according to the thin portion 30K, it is formed on the inner surface of each long wall 30X of the outer can 30 such that the surface is concave, and the concave stepped portion has a gentle slope. Thereby, when inserting the electrode body 20 into the outer can 30 in the manufacturing process of the power storage device 10, compared with the outer can in which a concave shape with a stepped portion of 90° is formed, it is possible to prevent the electrode body 20 from being damaged by the concave stepped portion.

[0044] Another example of the outer can 30 of the present embodiment will be described with reference to FIG. 6. FIG. 6 is a front view of the power storage device 10.

[0045] As illustrated in FIG. 6, a thin portion 30L is formed along the width direction on the long wall 30X of the outer can 30, which is another example of the present embodiment. The thin portion 30L is formed such that the stepped portion (specifically, the start position and the end position of the stepped portion) is substantially rectangular when viewed from the depth direction. In other words, the shape of the opening edge of the thin portion L is substantially rectangular. The thin portion 30L is the same as the above-described thin portion 30J except that the stepped portion is formed in a rectangular shape. By adopting such a configuration, substantially the same effects as the effects of the power storage device 10 in which the above-described thin portion 30J is formed are exhibited.

[0046] Another example of the outer can 30 of the present embodiment will be described with reference to FIG. 7. FIG. 7 is a cross-sectional view corresponding to the AA cross-section of FIG. 2 of the power storage device 10.

[0047] As illustrated in FIG. 7, in another example of the present embodiment, a thin portion 30M is formed along the width direction on the long wall 30X of the outer can 30. The stepped portion of the concave shape of the thin portion 30M is formed vertically. The thin portion 30M is the same as the above-described thin portion 30J except that the stepped portion is formed vertically. By adopting such a configuration, an effect substantially the same as that of the power storage device 10 in which the above-described thin portion 30J is formed is achieved.

[0048] Using FIG. 8, a power storage module 100 including the power storage device 10 will be described. FIG. 8 is a cross-sectional view corresponding to the AA cross-section of FIG. 2.

[0049] A power storage module 100 which is an example of the embodiment is mainly used as a power source for power. The power storage module 100 is used, for example, as a power source for electric devices driven by a motor such as a power tool, an electric assist bicycle, an electric motorcycle, an electric wheelchair, an electric tricycle, or an electric cart. However, the use of the power storage module 100 is not specified, and it may be used as a power source for electric devices other than electric devices, for example, various electric devices used indoors and outdoors such as a cleaner, a wireless device, a lighting device, a digital camera, or a video camera.

[0050] Hereinafter, for convenience of explanation, description will be made based on the depth direction as the first direction, the width direction as the second direction, and the height direction, which are the same as those of the power storage device 10.

[0051] As illustrated in FIG. 8, in the power storage module 100, the power storage devices 10 are arranged side by side along the depth direction, and a spacer 50 as a holding member is provided between adjacent power storage devices 10. A buffer member 60 is provided between the power storage device 10 and the spacer 50. In the power storage module 100 of the present embodiment, it is assumed that the power storage device 10 has the thin portion 30J formed on the long wall 30X of the outer can 30 described above, but it is not limited thereto. The power storage device 10 may have the thin portion 30K formed on the long wall 30X of the outer can 30 described above.

[0052] The spacer 50 insulates adjacent power storage devices 10 from each other and adjusts the depth dimension of the power storage module 100. The spacer 50 is made by molding a thermoplastic resin such as, for example, polypropylene, polystyrene, polycarbonate, polybutylene terephthalate, Noryl (registered trademark) resin (modified PPE), etc., but is not particularly limited.

[0053] The spacer 50 has a plate-shaped main body 50A that is substantially the same shape as the long wall 30X of the exterior can 30 when viewed from the depth direction, a lower-end holding portion 50B that holds the lower end portion of the power storage device 10, and an upper-end holding portion 50C that holds the upper end portion of the power storage device 10. More specifically, the lower-end holding portion 50B holds the vicinity of the bottom portion 30B of the exterior can 30, which is the lower end portion of the long wall 30X of the exterior can 30. Also, the upper-end holding portion 50C holds the vicinity of the joint portion between the exterior can 30 and the sealing plate 40, which is the upper end portion of the long wall 30X of the exterior can 30.

[0054] When the lower-end holding portion 50B of the spacer 50 holds the lower end portion of the long wall 30X and the upper-end holding portion 50C holds the upper end portion of the long wall 30X, deformation of the upper and lower end portions of the long wall 30X can be suppressed when the power storage device 10 bulges, and mechanical stress generated at the joint portion between the exterior can 30 and the sealing plate 40 at the upper end portion can be reduced. As a result, the risk of breakage of the joint portion is eliminated, and the reliability of the power storage device 10 can be improved.

[0055] The buffer member 60 is made of a material softer than the spacer 50, and examples thereof include thermosetting elastomers such as natural rubber, synthetic rubber, urethane rubber, silicone rubber, and fluororubber, and thermoplastic elastomers such as polystyrene, olefin, polyurethane, polyester, and polyamide. Note that these materials may be foamed, but are not particularly limited.

[0056] The buffer member 60 is provided between the long wall 30X of the outer can 30 and the main body 50A of the spacer 50, and holds the substantially central portion in the height direction of the long wall 30X of the outer can 30. The size of the buffer member 60 in the width direction is, for example, equal to or greater than the size of the electrode body 20 in the width direction, and is preferably substantially the same as the size of the long wall 30X of the outer can 30. The size of the buffer member 60 in the height direction is, for example, equal to or greater than the size of the electrode body 20 in the height direction, and is preferably smaller than the interval between the lower end holding portion 50B and the upper end holding portion 50C of the spacer 50. With the above size, the buffer member can press the surfaces of the positive electrode plate and the negative electrode plate of the electrode body 20 more uniformly.

[0057] Here, when the buffer member 60 holds the substantially central portion in the height direction of the long wall 30X, when the power storage device 10 bulges, the bulge of the central portion of the long wall 30X can be absorbed. Thereby, for example, the reaction force on the holding member can be reduced and the power storage module can be miniaturized as compared with the case where the central portion of the long wall 30X is held by a rigid body.

[0058] The effects of the power storage module 100 including the power storage device 10 will be described with reference to FIG. 9.

[0059] As illustrated in FIG. 9, when the power storage device 10 bulges, although the central portion of the long wall 30X deforms so as to bulge outward, the upper end holding portion 50C of the spacer 50 holds the joint portion between the outer can 30 and the sealing plate 40, whereby the mechanical stress generated in the joint portion can be reduced. As a result, there is no risk of the joint portion breaking, and the reliability of the power storage device 10 can be improved. Further, the buffer member 60 absorbs the bulge of the central portion of the long wall 30X, and for example, the reaction force on the holding member can be reduced and the power storage module can be miniaturized as compared with the case where the central portion of the long wall 30X is held by a rigid body.

[0060] Note that the present disclosure is not limited to the above-described embodiments and their modifications, and it goes without saying that various changes and improvements can be made within the scope of the matters described in the claims of the present application. For example, in the above embodiment, a power storage device using one sealing plate for an outer packaging can is described. However, it is not limited to this configuration. For example, sealing plates may be joined and sealed to the openings at both ends of the cylindrical side wall portion, respectively. At this time, the thin-walled portions may be provided near both sealing plates. At this time, a spacer may be provided between the sealing plate and the electrode body so that the electrode body is separated from both sealing plates by a predetermined distance. With this configuration, it becomes easier to press only the electrode body 20 without pressing the thin-walled portion.

Description of Reference Numerals

[0061] 10 Power storage device, 20 Electrode body, 21 Positive electrode lead, 22 Negative electrode lead, 23 Current collecting member, 24 Current collecting member, 25 Insulating member, 26 Insulating member, 29 Insulating holder, 30 Outer packaging can, 30B Bottom, 30H Opening, 30J Thin-walled portion, 30K Thin-walled portion, 30L Thin-walled portion, 30M Thin-walled portion, 30X Long wall, 30Y Short wall, 40 Sealing plate, 41 Positive electrode terminal, 42 Negative electrode terminal, 45 Pressure regulating valve, 50 Spacer, 50A Body, 50B Lower end holding portion, 50C Upper end holding portion, 60 Buffer member, 100 Power storage module.

Claims

1. An electrode body in which a positive electrode plate and a negative electrode plate are laminated via a separator, An exterior can that houses the electrode body and an electrolytic solution, and has a cylindrical side wall portion and an opening formed at at least one end of the side wall portion, A sealing plate that closes the opening of the exterior can, comprising: A joint portion is formed where the periphery of the sealing plate and the opening are joined, On a pair of side walls facing each other in the first direction of the side wall portion, a thin portion extending in a second direction orthogonal to the first direction is formed, The stepped portion above the thin portion is arcuate and bulges upward when viewed from the first direction, and the stepped portion below the thin portion is arcuate and bulges downward when viewed from the first direction, A power storage device.

2. The power storage device according to claim 1, The thin portion is formed between the joint portion with the sealing plate and the electrode body, A power storage device.

3. The power storage device according to claim 1 or 2, In the thin portion extending in the second direction, the size in the direction perpendicular to the second direction at the center portion in the second direction is larger than the size in the direction perpendicular to the second direction at the end portion in the second direction of the thin portion, A power storage device.

4. The power storage device according to any one of claims 1 to 3, The thin portion is formed such that the outer surface of the side wall of the exterior can is concave, A power storage device.

5. The power storage device according to claim 4, The stepped portion of the concave shape is formed obliquely, A power storage device.

6. The power storage device according to any one of claims 1 to 5, The first direction is parallel to the direction in which the positive electrode plate and the negative electrode plate are stacked. Power storage device.

7. A power storage module including a plurality of the power storage devices according to any one of claims 1 to 6, wherein the plurality of power storage devices are arranged side by side in the first direction, and a holding member is provided between adjacent ones of the plurality of power storage devices. Power storage module.

8. The power storage module according to claim 7, wherein the holding member holds at least the vicinity of the joint portion in a third direction perpendicular to the sealing plate. Power storage module.

9. The power storage module according to claim 7 or 8, further including a buffer member between the power storage device and the holding member, wherein the buffer member holds the central portion of the exterior can in a third direction perpendicular to the sealing plate and is made of a material softer than the holding member. Power storage module.

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