Power storage device

Abstract

The power storage device (1) includes: a plurality of cylindrical electrode bodies; and a thin film outer body (4), which has a plurality of housings (12) that individually wrap the plurality of electrode bodies, and a sealing portion (14) that seals each housing (12) and connects the plurality of housings (12) to each other, and extends in a zigzag shape between adjacent housings (12) in a zigzag or curved manner.

Description

Technical Field

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

[0002] A power storage module that mounts multiple cylindrical power storage devices (e.g., batteries) is known (see, for example, Patent Document 1). In the power storage module disclosed in Patent Document 1, the multiple power storage devices have cylindrical outer cans, each of which houses a wound electrode assembly.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2014-170613 Summary of the Invention

[0006] Technical problem to be solved by the invention

[0007] Energy storage modules are sometimes used as power sources for vehicles or portable devices. Therefore, there is a desire to reduce the weight of these modules. One approach to reducing the weight of these modules is to enclose multiple electrode bodies in a common film outer casing while maintaining their respective sealing properties. This results in an energy storage device having multiple electrode bodies. In this case, the outer canister housing each electrode body can be eliminated, further reducing the weight of the energy storage module.

[0008] When multiple electrode bodies are sealed within a thin film outer casing, high sealing performance is required for each electrode body to ensure safety and power generation performance of the battery module. To achieve this high sealing performance, a large sealing portion is desirable that encompasses the electrode body housing. However, a larger sealing portion increases the spacing between adjacent electrode bodies, increasing the external dimensions of the battery storage device and potentially reducing the energy density of the battery storage module.

[0009] The present disclosure has been made in view of such circumstances, and one object of the present disclosure is to provide a technology for improving the energy density of a power storage module while suppressing a decrease in the sealing performance of an electrode assembly.

[0010] Methods used to solve technical problems

[0011] One aspect of the present disclosure is an electricity storage device. The electricity storage device includes: a plurality of cylindrical electrode bodies; and a thin film outer casing having a plurality of housings that individually enclose the plurality of electrode bodies; and a sealing portion that seals each housing and connects the plurality of housings together, the outer casing extending in a zigzag pattern, zigzagging or curving between adjacent housings.

[0012] Another embodiment of the present disclosure is a power storage module comprising a plurality of power storage devices according to the above embodiment and a bracket for holding the plurality of power storage devices.

[0013] Another solution disclosed in the present invention is a storage device. The storage device includes: a plurality of cylindrical electrode bodies; and a thin film outer body, which has a plurality of housings that individually wrap the plurality of electrode bodies, and a sealing portion that seals each housing and connects the plurality of housings to each other, bends between adjacent housings, and meanders in the arrangement direction of the electrode bodies. The sealing portion includes: a first connecting portion and a second connecting portion, which are clamped by two adjacent housings and connect the two housings, and an outer edge portion, which is further outward than each housing in the axial direction of the electrode body and extends over the plurality of housings. The first connecting portion and the second connecting portion are staggered in the arrangement direction of the electrode bodies, and are staggered with each other in a direction orthogonal to the axial direction and the arrangement direction, and extend in the arrangement direction. The outer edge portion includes a first tilted portion, which is continuous from the first connecting portion and the receiving portion, and has a concave portion that bends toward the second connecting portion in a direction perpendicular to the first connecting portion, starting from the first connecting portion and the connection portion with the receiving portion, and fits between adjacent receiving portions; and a second tilted portion, which is continuous from the second connecting portion and two first tilted portions arranged with the second connecting portion sandwiched therebetween, and bends toward the first connecting portion in a direction perpendicular to the first connecting portion, starting from the second connecting portion and the connection portion with the two first tilted portions. When viewed in the axial direction, the first tilted portion and the second tilted portion overlap on the receiving portion to form an overlapping portion.

[0014] Optional combinations of the above-described constituting elements and modes in which the present disclosure is converted into methods, apparatuses, systems, etc. may also be effective as modes of the present disclosure.

[0015] Effects of the Invention

[0016] According to the present disclosure, it is possible to improve the energy density of the electricity storage module while suppressing a decrease in the sealing performance of the electrode assembly. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a perspective view of the power storage device according to the first embodiment.

[0018] Figure 2 (A) is a schematic diagram of the power storage device viewed from the axial direction. Figure 2 (B) is a schematic diagram of the power storage device viewed from the second direction.

[0019] Figure 3 (A)~ Figure 3 (C) is a process diagram of a method for manufacturing an electricity storage device.

[0020] Figure 4 (A)~ Figure 4 (C) is a step of the method for manufacturing the power storage device.

[0021] Figure 5 This is a perspective view of the power storage module according to the first embodiment.

[0022] Figure 6 This is an exploded perspective view of the power storage module.

[0023] Figure 7 This is a perspective view showing an enlarged portion of the electricity storage module.

[0024] Figure 8 This is a perspective view of a power storage module according to the second embodiment.

[0025] Figure 9 This is an exploded perspective view of the power storage module.

[0026] Figure 10 It is a cross-sectional view of the power storage module.

[0027] Figure 11 It is a perspective view of a power storage device according to a third embodiment.

[0028] Figure 12 It is a perspective view of the power storage device before the outer edge portion is folded.

[0029] Figure 13 This is a diagram showing the power storage device as viewed from the axial direction.

[0030] Figure 14 (A) and Figure 14 (B) is a perspective view of a portion of the power storage device viewed from one side in the orthogonal direction.

[0031] Figure 15 (A) and Figure 15 (B) is a perspective view of a portion of the power storage device viewed from the other side in the orthogonal direction.

[0032] Figure 16 A diagram showing an arrangement of a plurality of power storage devices.

[0033] Figure 17 It is a schematic diagram for explaining the arrangement of electrode leads.

[0034] Figure 18 (A)~ Figure 18 (C) is a process diagram of a method for manufacturing an electricity storage device.

[0035] Figure 19 (A)~ Figure 19 (C) is a process diagram of a method for manufacturing an electricity storage device. DETAILED DESCRIPTION

[0036] Below, the present disclosure is described with reference to the accompanying drawings based on preferred embodiments. The embodiments do not limit the present disclosure but are illustrative, and all the features or combinations thereof described in the embodiments do not necessarily represent the essential content of the present disclosure. The same or equivalent components, parts, and processes shown in the drawings are marked with the same figure marks, and repeated descriptions are appropriately omitted. In addition, the scales or shapes of the various parts shown in the drawings are conveniently set for easy explanation, and are not interpreted as restrictive unless otherwise specified. In addition, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, the terms do not indicate any order or importance, but are used to distinguish one configuration from other configurations. In addition, in the drawings, a part of unimportant components is omitted for display when describing the embodiments.

[0037] (Implementation Method 1)

[0038] Figure 1 It is a perspective view of the power storage device 1 according to the first embodiment. Figure 2 (A) is a schematic diagram of the power storage device 1 viewed from the axial direction A. Figure 2 (B) is a schematic diagram of the power storage device 1 viewed from the second direction C. Figure 2 In (B), for convenience of explanation, the interior of the film outer casing 4 is also shown. In addition, the state before the film outer casing 4 is folded is shown by the dotted line. In this embodiment, the direction in which the winding axis of the electrode body 2 extends is referred to as the axial direction A, the direction in which the plurality of electrode bodies 2 are arranged is referred to as the first direction B (sometimes referred to as the arrangement direction B in this disclosure), and the direction orthogonal to the axial direction A and the first direction B is referred to as the second direction C (sometimes referred to as the orthogonal direction C in this disclosure).

[0039] The power storage device 1 of this embodiment is, for example, a rechargeable secondary battery such as a lithium-ion battery, a nickel-hydrogen battery, or a nickel-cadmium battery, or a capacitor such as an electric double-layer capacitor. The power storage device 1 includes a plurality of electrode bodies 2 and a thin film outer casing 4. While the power storage device 1 of this embodiment includes eight electrode bodies 2, the number is not particularly limited; it may be two or more.

[0040] Each electrode body 2 is cylindrical and has a first strip-shaped electrode plate and a second strip-shaped electrode plate stacked with an electrode spacer, and a wound structure wound in a coiled shape. As an example, the first electrode plate is a negative electrode plate and the second electrode plate is a positive electrode plate. A first electrode lead 8 is electrically connected to the first electrode plate. A second electrode lead 10 is electrically connected to the second electrode plate. For example, the first electrode lead 8 and the second electrode lead 10 are strip-shaped, and one end of each is welded to each electrode plate. The plurality of electrode bodies 2 are arranged in a first direction B with predetermined intervals in a manner such that the axial directions A of the electrode bodies 2 are parallel to each other. The plurality of electrode bodies 2 are wrapped by a common thin film outer casing 4.

[0041] The film outer casing 4 has, for example, a structure in which two laminate films are laminated. Each laminate film has, for example, a structure in which thermoplastic resin sheets are laminated on both sides of a metal sheet such as aluminum. In addition, the film outer casing 4 has a plurality of accommodating portions 12 and a sealing portion 14. The plurality of accommodating portions 12 are arranged in a first direction B at predetermined intervals. Each accommodating portion 12 is cylindrical and wraps each electrode body 2 to accommodate it. Each accommodating portion 12 is composed of a bag portion provided on the film outer casing 4. The bag portion is a portion that separates the two laminate films from each other. Therefore, each accommodating portion 12 protrudes from the sealing portion 14 along the shape of the side surface of the electrode body 2. That is, each accommodating portion 12 bulges in the thickness direction of the film outer casing 4. In each accommodating portion 12, an electrolyte 16 is accommodated together with the electrode body 2.

[0042] Seal 14 surrounds the periphery of each container 12, sealing each container 12. Seal 14 is formed, for example, from a welded portion of a thermoplastic resin sheet. The welded portion is formed by thermocompression-bonding the periphery of the bag portion of the film exterior 4, fusing the two thermoplastic resin sheets of the laminate film together. Seal 14 seals each container 12 and interconnects the plurality of containers 12.

[0043] The end of the first electrode lead 8 and the second electrode lead 10 on the opposite side to the side connected to the electrode body 2 protrudes outside the film outer body 4. The interface between each electrode lead and the film outer body 4 is sealed by a well-known sealant. In this embodiment, the first electrode lead 8 and the second electrode lead 10 connected to each electrode body 2 protrude to opposite sides of each other in the axial direction A. In addition, each first electrode lead 8 protrudes to the same side. In addition, the first electrode lead 8 and the second electrode lead 10 may also protrude to the same side in the axial direction A.

[0044] The film exterior body 4 zigzags or bends between adjacent housing portions 12, extending in a zigzag pattern. That is, the film exterior body 4 meanders in the first direction B. By folding the film exterior body 4 in a zigzag pattern, the spacing between the housing portions 12 in the first direction B can be narrowed compared to the pre-folded state, thereby shortening the length of the energy storage device 1 in the first direction B. Furthermore, the multiple housing portions 12 in this embodiment are arranged so that, when the film exterior body 4 extends in a zigzag pattern, their centers are aligned on the same straight line when viewed from the axial direction A. This prevents the size of the energy storage device 1 in the second direction C from increasing compared to a case where the multiple housing portions 12 are arranged with their centers staggered in the second direction C. Furthermore, in this embodiment, each housing portion 12 protrudes further outward in the second direction C than the sealing portion 14 in the zigzag-bent state. In other words, the sealing portion 14 in the zigzag-bent state is accommodated further inward in the second direction C than the housing portion 12. Thus, by folding the film exterior body 4 , the size of the power storage device 1 in the second direction C can be further suppressed while reducing the size of the power storage device 1 in the first direction B. In the present disclosure, the centers of the plurality of housings 12 do not necessarily need to be on the same straight line.

[0045] Specifically, the sealing portion 14 includes a pair of first side portions 14a and a pair of second side portions 14b that surround each accommodating portion 12. The pair of first side portions 14a are arranged in the axial direction A, sandwiching each accommodating portion 12, and seal the ends of each accommodating portion 12 in the axial direction A. In this embodiment, the first side portions 14a extend linearly through the center of the accommodating portion 12 as viewed in the axial direction A. The pair of second side portions 14b are arranged in a direction perpendicular to the axial direction A, sandwiching each accommodating portion 12, and extend in the axial direction A, connecting the pair of first side portions 14a.

[0046] The two second sides 14b located between two adjacent receiving portions 12 have a predetermined angle θ with each other, that is, they are connected non-linearly. In addition, the directions in which the connecting portions of the two second sides 14b are bent or curved are different from each other at the multiple connecting portions arranged in the first direction B. As a result, the film outer cover 4 extends in a zigzag shape in the first direction B. In addition, when the connecting portion is bent, the angle θ formed by the two second sides 14b is, for example, the angle at which the extension line of the first side 14a corresponding to (connected to) the receiving portion 12 on one side intersects with the extension line of the first side 14a corresponding to the receiving portion 12 on the other side.

[0047] Preferably, the connecting portion is curved. This can prevent the film outer body 4 from breaking or the two laminated films from peeling off at the connecting portion, thereby reducing the sealing performance of each receiving portion 12. Furthermore, preferably, the film outer body 4 is bent or curved so that the two first sides 14a corresponding to the two adjacent receiving portions 12 extend in directions intersecting each other. That is, the bending amount (angle amount) or bending amount (angle amount) of the two second sides 14b from the straight state is less than 180°, and the two adjacent first sides 14a extend non-parallel to each other.

[0048] Thus, compared to the case where the two first sides 14a are bent or curved to become parallel, it is easy to avoid the sealing portion 14 protruding further outward than the accommodating portion 12 in the second direction C. Alternatively, the protruding amount of the sealing portion 14 can be reduced. Therefore, the size of the power storage device 1 can be suppressed from becoming larger in the second direction C. More preferably, the angle θ formed by the two second sides 14b is an obtuse angle (higher than 90° and less than 180°). In other words, the bending amount (angle amount) or the bending amount (angle amount) is higher than 0° and less than 90°. Thus, the pressure applied to the connecting portion can be reduced. Therefore, it is further suppressed that the sealing portion 14 breaks or the two laminated films peel off at the connecting portion, and the sealing performance of each accommodating portion 12 is reduced.

[0049] Next, an example of a method for manufacturing the power storage device 1 will be described. Figure 3 (A)~ Figure 3 (C) and Figure 4 (A)~ Figure 4 (C) is a process diagram of a method for manufacturing the power storage device 1. First, Figure 3 As shown in (A), a first laminate film 20a is prepared. A plurality of semi-cylindrical depressions 18 are pre-formed in the first laminate film 20a. The plurality of depressions 18 are formed, for example, by subjecting the first laminate film 20a to a known process such as stamping. An electrode body 2 is placed in each depression 18. A first electrode lead 8 and a second electrode lead 10 are pre-connected to the electrode body 2. A sealant (not shown) is provided in the first electrode lead 8 and the second electrode lead 10.

[0050] Then, if Figure 3 As shown in (B), the second laminate film 20b overlaps the first laminate film 20a to form a thin film outer package 4. On the second laminate film 20b, semi-cylindrical recesses 18 are provided at positions opposite to the recesses 18 of the first laminate film 20a. Therefore, by overlapping the first laminate film 20a and the second laminate film 20b, a housing 12 is formed by a pair of recesses 18. The method of forming the recess 18 on the second laminate film 20b is the same as the method of forming the recess 18 on the first laminate film 20a. When the electrode body 2 is accommodated in the housing 12, the front end of the first electrode lead 8 and the front end of the second electrode lead 10 protrude outside the thin film outer package 4.

[0051] Then, if Figure 3 As shown in (C), a portion of the film outer casing 4 is subjected to a heat-compression bonding treatment to form a welded portion 22. The portion of the film outer casing 4 that is not subjected to the heat-compression bonding treatment is a non-welded portion 24. The non-welded portion 24 is configured to connect each housing portion 12 and the outside of the film outer casing 4. In this embodiment, the non-welded portion 24 is provided in such a manner that the protruding side of the first electrode lead 8 among the four sides of each housing portion 12 is connected to the outside of the film outer casing 4. The remaining three sides of each housing portion 12 are surrounded by the welded portion 22. The interface between the film outer casing 4 and the second electrode lead 10 is sealed by a sealant.

[0052] Then, if Figure 4 As shown in (A), the electrolyte 16 is injected into each housing portion 12 through the non-welded portion 24. After the electrolyte 16 is injected, as shown in FIG. Figure 4 As shown in (B), the non-welded portion 24 is also subjected to a heat-compression bonding process. As a result, a sealing portion 14 is formed around the entire periphery of each housing portion 12. The interface between the film outer body 4 and the first electrode lead 8 is sealed with a sealant. Figure 4 As shown in (C), the film outer cover 4 is bent into a Z-shape. Through the above steps, the power storage device 1 is obtained.

[0053] The method for manufacturing the electricity storage device 1 is not limited to the above method. For example, a laminate film having a length twice that of the electricity storage device 1 may be used, and each electrode body 2 may be wrapped by folding the laminate film in half. In addition, if the required amount of electrolyte 16 is small, the electrolyte 16 may be pre-impregnated into the electrode separator, thereby eliminating the need for the electrolyte 16. Figure 4 The electrolyte 16 injection process shown in (A) is performed. Figure 3 In the thermocompression bonding step shown in (C), the entire circumference of each housing portion 12 is subjected to thermocompression bonding to form the sealed portion 14 .

[0054] The power storage device 1 of this embodiment can be incorporated into a power storage module 100 described below. Figure 5 This is a perspective view of the power storage module 100 according to the first embodiment. Figure 6 It is an exploded perspective view of the power storage module 100 . Figure 7 This is a perspective view showing an enlarged portion of the electricity storage module 100 .

[0055] The power storage module 100 includes a plurality of power storage devices 1, spacers 102, brackets 104, insulating plates 106, and bus bars 108. The power storage module 100 of this embodiment includes eight power storage devices 1, but the number is not particularly limited and may be two or more.

[0056] The plurality of power storage devices 1 are arranged in the second direction C with their respective housings 12 aligned in the same direction. The plurality of power storage devices 1 are divided into two units 110. The number of power storage devices 1 constituting a unit 110 is not limited to two.

[0057] In each unit 110, the two energy storage devices 1 are arranged with an offset in the first arrangement direction B, such that the axis of the electrode body 2 of one energy storage device 1 is positioned between the axis centers of the adjacent electrode bodies 2 of the other energy storage device 1. In other words, the housing 12 of one energy storage device 1 fits between the recesses of the two housings 12 of the other energy storage device 1. This allows the size of each unit 110 to be reduced in the second direction C.

[0058] In each cell 110, a spacer 102 is arranged between two power storage devices 1. Spacers 102, also known as insulating washers, are used to electrically insulate two adjacent power storage devices 1, to maintain contact between the power storage devices 1, or to absorb tolerances in the installation of multiple power storage devices 1. Spacer 102 can be, for example, a corrugated plate with repeated convex and concave portions in a first direction B, or a plate having a thickness greater than a corrugated plate and having multiple concave portions arranged in the first direction B on both sides. Spacer 102 is made of, for example, an insulating resin. Examples of resins that can be used to construct spacer 102 include thermoplastic resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and Noryl (registered trademark) resin (modified PPE). Alternatively, spacer 102 can be made of an elastic material such as polyurethane, or a thermal insulator such as silica. Furthermore, spacer 102 can be made of a metal such as aluminum, an aluminum alloy, or steel, as long as it can maintain insulation between power storage devices 1.

[0059] Multiple power storage devices 1 are held by multiple brackets 104. Each bracket 104 has a side plate 112 and a pair of protrusions 114. The side plate 112 is a rectangular plate extending in a first direction B. The pair of protrusions 114 are rectangular plates that protrude from both ends of the side plate 112 in the first direction B toward the second direction C. The pair of protrusions 114 face each other in the first direction B. Therefore, the bracket 104 has a generally U-shaped shape that is elongated in the first direction B. The bracket 104 is positioned so that the main surface of the side plate 112 faces the second direction C, and the main surface of each protrusion 114 faces the first direction B.

[0060] As an example, each bracket 104 is composed of one sheet of plate. The side plate 112 and the pair of protrusions 114 can be formed by bending the two ends of the metal plate. In addition, if the rigidity above the prescribed level is obtained, the bracket 104 can also be made of resin. In addition, the side plate 112 and the protrusion 114 that are single bodies can be joined to form the bracket 104. Examples of the metal used for the bracket 104 include aluminum, aluminum alloy, steel, etc. In addition, examples of the resin used for the bracket 104 include thermoplastic resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), Noryl (registered trademark) resin (modified PPE); fiber reinforced plastics (FRP) including carbon fiber reinforced plastics or glass fiber reinforced plastics, etc.

[0061] Each bracket 104 is mounted one-to-one to each cell 110. Each cell 110 is surrounded by the bracket 104 on three sides in the first direction B and the second direction C. The side plate 112 covers one surface of the cell 110 in the second direction C. The pair of protrusions 114 covers two surfaces of the cell 110 in the first direction B. As an example, the side plate 112 is fixed to the opposing power storage device 1 using an adhesive. The adhesive is preferably an insulating adhesive. In addition, an insulating sheet (not shown) may be provided between the cell 110 and the bracket 104.

[0062] Each unit 110 is arranged in the second direction C with the bracket 104 attached. At this point, each unit 110 is positioned so that its exposed surface, not covered by the bracket 104, faces the same direction. When the units 110 are arranged, the exposed surface of each unit 110 is covered by a side plate 112 attached to the bracket 104 of the adjacent unit 110 and secured with an adhesive. Thus, each unit 110 is sandwiched in the second direction C by a pair of side plates 112. Furthermore, the side plate 112 located between two units 110 is sandwiched between the two power storage devices 1.

[0063] Each protrusion 114 has a front end 114a and a base end 114b. The base end 114b is interposed between the side plate 112 and the front end 114a. The front end 114a is offset relative to the base end 114b in a direction away from the unit 110. Therefore, the distance between the pair of protrusions 114 is greater on the front end 114a side than on the base end 114b side. Furthermore, each front end 114a protrudes to a position where it overlaps with the base end 114b of the adjacent bracket 104 when viewed from the first direction B.

[0064] In other words, when multiple units 110 are arranged in the second direction C, between two adjacent brackets 104, the side plates 112 and the pair of base ends 114b of one bracket 104 enter between the pair of front ends 114a of the other bracket 104. Furthermore, the overlapping portion of the front end 114a of one bracket 104 and the base end 114b of the other bracket 104 is subjected to a known joining process such as laser welding to form a joint 116. As a result, the brackets 104 are connected, and the multiple brackets 104 hold the multiple power storage devices 1.

[0065] The side plate 112 has multiple recesses 112a arranged in the first direction B. Each recess 112a is groove-shaped and extends in the axial direction A. Furthermore, when the unit 110 is mounted with the bracket 104, the housings 12 of the power storage device 1 facing the side plate 112 fit into the recesses 112a. As a result, the side plate 112 extends along the curved surface of each housing 12. This allows the power storage device 1 to be more stably held. In particular, displacement of the power storage device 1 in the first direction B is restricted.

[0066] Furthermore, the side plate 112 of this embodiment has a corrugated plate shape with repeated concavities and convexities in the first direction B. That is, when viewed from one main surface, a plurality of concave portions 112a and a plurality of convex portions 112b are arranged alternately in the first direction B. Therefore, the respective housings 12 of the storage devices 1 arranged on both sides of the side plate 112 can be embedded in the side plate 112. Specifically, for the concave portions 112a and convex portions 112b when viewing the side plate 112 from one main surface, the respective housings 12 of one storage device 1 are embedded in each concave portion 112a. Furthermore, the respective housings 12 of another storage device 1 are embedded from the inner side of each convex portion 112b (which is a concave portion when viewed from the opposite side). This further improves the stability of each storage device 1 in the storage module 100.

[0067] Furthermore, there are no other units 110 on the exposed surface of the unit 110 located at one end in the second direction C. Therefore, an end bracket 105 is attached to the exposed surface of this unit 110. The end bracket 105 has the same shape as the bracket 104, except that the protrusion 114 protrudes in the opposite direction to the bracket 104 and the protrusion 114 does not have the front end 114a.

[0068] When the multiple cells 110 are connected, busbars 108 are placed on both sides of the multiple cells 110 in the axial direction A via insulating plates 106. Furthermore, the first electrode lead 8 and the second electrode lead 10 of each power storage device 1 are electrically connected to the busbar 108. For example, each electrode lead is joined to the busbar 108 by a known joining process such as laser welding. The presence of insulating plates 106 between the cells 110 and the busbar 108 can suppress electrical connection between each power storage device 1 and the busbar 108 at portions other than the electrode leads. The insulating plates 106 only need to be an insulator having a predetermined hardness and can be made of the same material as the spacer 102 or another material.

[0069] In this embodiment, the two power storage devices 1 in each cell 110 are positioned so that their respective first electrode leads 8 protrude toward the same side. Furthermore, each cell 110 is positioned so that the protruding directions of the first electrode leads 8 differ from one another. Consequently, when each electrode lead is bonded to the bus bar 108, the electrode bodies 2 within each cell 110 are connected in parallel, and the cells 110 are connected in series.

[0070] Furthermore, the electrical connection scheme for each electrode assembly 2 is not particularly limited. For example, in each power storage device 1, the first electrode leads 8 and second electrode leads 10 may be arranged in a staggered manner, with adjacent first and second electrode leads 8 and 10 electrically connected. In other words, multiple electrode assemblies 2 may be connected in series in each power storage device 1. Furthermore, in each cell 110, two power storage devices 1 may be connected in series. Furthermore, all electrode assemblies 2 mounted in the power storage module 100 may be connected in series or in parallel.

[0071] Furthermore, the first electrode lead 8 and the second electrode lead 10 can protrude toward the same side in the axial direction A. This allows electrical connection of the electrode bodies 2 simply by placing the insulating plate 106 and the bus bar 108 on one side of the power storage module 100. This reduces the number of components and assembly steps required for the power storage module 100.

[0072] As described above, the energy storage device 1 of this embodiment includes: multiple cylindrical electrode bodies 2; and a thin film exterior body 4 having multiple housings 12 that individually enclose the multiple electrode bodies 2, and a sealing portion 14 that seals each housing 12 and interconnects the multiple housings 12. Furthermore, the thin film exterior body 4 zigzags or bends between adjacent housings 12, extending in a zigzag pattern. Furthermore, the energy storage module 100 of this embodiment includes multiple energy storage devices 1 and a holder 104 that holds the multiple energy storage devices 1.

[0073] When multiple chambers 12 individually house electrode assemblies 2, the generation of gas within the chambers 12 and the expansion of the electrode assemblies 2 during charging and discharging of the electricity storage device 1 may place a significant load on the sealing portion 14. If the sealing portion 14 is damaged, allowing the interior of the chamber 12 to connect to the exterior of the film outer casing 4, the electrolyte 16 may leak out of the film outer casing 4. Furthermore, if the sealing portion 14 is damaged, allowing adjacent chambers 12 to connect, the adjacent electrode assemblies 2 may short-circuit, causing an imbalance in the amount of electrolyte 16 within the two chambers 12, potentially reducing the power generation performance of the electricity storage device 1.

[0074] Therefore, in order to ensure the sealing performance of the electrode body 2, it is expected that the area of ​​the sealing portion 14 will be increased to improve the strength of the sealing portion 14. In particular, in recent years, there has been a tendency to pursue higher capacitance of the power storage device 1, and as the capacitance increases, the amount of expansion of the electrode body 2 tends to increase. Therefore, the need to improve the strength of the sealing portion 14 is gradually increasing. However, the enlargement of the sealing portion 14 will lead to the enlargement of the power storage device 1. Moreover, the enlargement of the power storage device 1 will lead to a decrease in the filling rate of the electrode body 2 in the power storage module 100, that is, the energy density of the power storage module 100. On the other hand, if the sealing portion 14 is reduced in order to increase the energy density of the power storage module 100, the sealing performance of the electrode body 2 will be sacrificed.

[0075] In contrast, in the energy storage device 1 of this embodiment, the film exterior body 4 is folded in a zigzag pattern. This allows the spacing between adjacent housings 12, and consequently the length of the energy storage device 1, to be shortened compared to a case where the film exterior body 4 is not folded, without reducing the size of the sealing portion 14. As a result, the number of electrode assemblies 2 mounted in the energy storage module 100 can be increased, or the energy storage module 100 can be miniaturized without reducing the number of electrode assemblies 2 mounted. In other words, according to this embodiment, the energy density of the energy storage module 100 can be improved while suppressing a decrease in the sealing performance of the electrode assemblies 2.

[0076] Furthermore, the pouch structure in which the plurality of electrode assemblies 2 are sealed by the film outer casing 4 allows the weight of the electricity storage module 100 to be reduced compared to a case in which each electrode assembly 2 is individually sealed by an outer can. This significant weight reduction effect is particularly achieved when the number of electrode assemblies 2 mounted in the electricity storage module 100 increases as the capacity of the electricity storage module 100 increases.

[0077] In addition, the sealing portion 14 of this embodiment has a first side portion 14a that seals the end of each housing portion 12 in the axial direction A of the electrode body 2. Moreover, the thin film outer casing 4 is bent or curved so that the two first sides 14a corresponding to two adjacent housing portions 12 extend in directions intersecting with each other. As a result, it is easy to avoid the sealing portion 14 protruding further outward than the housing portion 12 in the second direction C. Alternatively, the amount of protrusion of the sealing portion 14 can be reduced. As a result, since the size of the storage device 1 in the second direction C can be suppressed, the energy density of the storage module 100 can be further improved.

[0078] Furthermore, the bracket 104 of this embodiment includes a side plate 112 extending in the direction (first direction B) in which the multiple accommodating portions 12 are arranged. Furthermore, the side plate 112 includes multiple recesses 112a arranged in the first direction B, into which each accommodating portion 12 fits. This allows for more stable retention of the power storage device 1. Consequently, the electrical connection between each power storage device 1 and the bus bar 108 can be more stably maintained, further minimizing damage to each power storage device 1. Consequently, the power generation performance and safety of the power storage module 100 can be improved.

[0079] Furthermore, the side plates 112 of this embodiment have a corrugated shape with repeated concavities and convexities in the first direction B, and are sandwiched between the two energy storage devices 1. Furthermore, the housings 12 of one energy storage device 1 fit into the concave portions 112a when viewed from one main surface, while the housings 12 of the other energy storage device 1 fit into the convex portions 112b when viewed from the same main surface. This further improves the stability of each energy storage device 1 in the energy storage module 100.

[0080] (Implementation Method 2)

[0081] Embodiment 2 has the same structure as the first embodiment except for the structure for holding the power storage device 1. Hereinafter, this embodiment will be described focusing on the structures different from the first embodiment, and the common structures will be briefly described or omitted. Figure 8 This is a perspective view of a power storage module 100 according to the second embodiment. Figure 9 It is an exploded perspective view of the power storage module 100 . Figure 10 is a cross-sectional view of the power storage module 100 .

[0082] The energy storage module 100 of this embodiment includes multiple energy storage devices 1, a bracket 104, and a bus bar 108. The number of energy storage devices 1 included in the energy storage module 100, or the number of electrode bodies 2 included in each energy storage device 1, is not limited to the number shown in the figure. Each energy storage device 1 includes multiple electrode bodies 2 and a thin film outer casing 4. First electrode leads 8 and second electrode leads 10 protrude from each electrode body 2. The thin film outer casing 4 has multiple housings 12 and a sealing portion 14. The thin film outer casing 4 zigzags or bends between adjacent housings 12, extending in a zigzag pattern.

[0083] The plurality of power storage devices 1 are positioned so that their respective housings 12 are aligned in the same direction and are arranged in the second direction C. Two adjacent power storage devices 1 are staggered in the first direction B so that the housing 12 of one power storage device 1 fits between the recesses of the two housings 12 of the other power storage device 1 .

[0084] Multiple power storage devices 1 are held by a holder 104. Holder 104 in this embodiment is composed of a first plate 118 and a second plate 120. First plate 118 and second plate 120 are plate-shaped bodies that widen in first direction B and second direction C, and sandwich multiple power storage devices 1 in axial direction A. The materials constituting first plate 118 and second plate 120 are the same as those of holder 104 in Embodiment 1.

[0085] The surfaces of the first plate 118 and the second plate 120 facing the energy storage devices 1 are provided with a plurality of support portions 122, which are bottomed cylindrical recesses. The support portions 122 are arranged so as to overlap with the housings 12 of the energy storage devices 1 in the axial direction A, with the ends of the housings 12 in the axial direction A fitting into the support portions 122. For example, each plate and the energy storage devices 1 are secured with an adhesive. Alternatively, a plurality of posts (not shown) may be provided between the first plate 118 and the second plate 120 to connect the posts to the plates.

[0086] Furthermore, the first plate 118 and the second plate 120 are provided with a plurality of slits 124 extending in a zigzag pattern in the first direction B and penetrating the plates in the axial direction A. Each slit 124 divides the bottom of each support portion 122 and connects adjacent support portions 122, that is, extends across a plurality of support portions 122. The plurality of slits 124 are arranged so as to overlap with the sealing portion 14 of each power storage device 1 in the axial direction A, with the end portion (including the first side portion 14a) of each sealing portion 14 in the axial direction A penetrating the slits 124. As a result, the first electrode lead 8 and the second electrode lead 10 of each power storage device 1 protrude to the outside of the bracket 104. Alternatively, only the first electrode lead 8 and the second electrode lead 10 may be inserted through the slits 124.

[0087] Furthermore, a plurality of bus bar mounting surfaces 126 are provided on the surfaces of first plate 118 and second plate 120 opposite to power storage device 1. Thus, bracket 104 of this embodiment also functions as insulating plate 106 of Embodiment 1. Each bus bar mounting surface 126 is positioned between two slits 124 aligned along second direction C.

[0088] In a state where a first plate 118 and a second plate 120 are installed on a plurality of power storage devices 1 and a bus bar 108 is placed on a bus bar placement surface 126, the first electrode lead 8 and the second electrode lead 10 protruding from the slit 124 are electrically connected to the bus bar 108 extending in the first direction B. In this embodiment, all the first electrode leads 8 protrude to the same side. Therefore, when each electrode lead is joined to the bus bar 108, all the electrode bodies 2 are connected in parallel. In addition, as in embodiment 1, the scheme for electrically connecting each electrode body 2 is not particularly limited. In addition, the shape of the bus bar 108 is also not limited. For example, a plurality of bus bars connecting adjacent electrode bodies 2 in series can be arranged in the first direction B.

[0089] The holder 104 of this embodiment includes the first plate 118 and the second plate 120 , but may include only one plate. For example, by increasing the size of one plate in the axial direction A and providing a deeper support portion 122 , a plurality of power storage devices 1 can be held by only one plate.

[0090] This embodiment also suppresses degradation of the sealing properties of the electrode assembly 2 while achieving an improvement in the energy density of the electricity storage module 100. Furthermore, compared to the first embodiment, the number of components and assembly steps for the electricity storage module 100 can be reduced. Furthermore, according to the first embodiment, the number of electricity storage devices 1 mounted in the electricity storage module 100 can be changed more easily than in this embodiment.

[0091] (Implementation 3)

[0092] Figure 11 It is a perspective view of the power storage device 1 according to the third embodiment. Figure 12 2 is a perspective view of the power storage device 1 before the outer edge portion 26 is folded. Figure 11 , a portion of the electrode body 2 is shown by a dotted line. In this embodiment, the direction in which the winding axis of the electrode body 2 extends is defined as the axial direction A, the arrangement direction of the plurality of electrode bodies 2 is defined as the arrangement direction B, and the direction orthogonal to the axial direction A and the arrangement direction B is defined as the orthogonal direction C.

[0093] The power storage device 1 of this embodiment is, for example, a rechargeable secondary battery such as a lithium-ion battery, a nickel-hydrogen battery, or a nickel-cadmium battery, or a capacitor such as an electric double-layer capacitor. The power storage device 1 includes a plurality of electrode bodies 2 and a thin film outer casing 4. While the power storage device 1 of this embodiment includes eight electrode bodies 2, the number is not particularly limited; it may be two or more.

[0094] Each electrode body 2 is cylindrical, having a first strip-shaped electrode plate and a second strip-shaped electrode plate stacked with an electrode spacer, and a winding structure in which the electrode plates are wound in a coiled shape. As an example, the first electrode plate is a negative electrode plate, and the second electrode plate is a positive electrode plate. A first electrode lead 8 is electrically connected to the first electrode plate. A second electrode lead 10 is electrically connected to the second electrode plate. For example, the first electrode lead 8 and the second electrode lead 10 are strip-shaped (rectangular in one direction), and one end of each is welded to each electrode plate. The plurality of electrode bodies 2 are positioned in a manner such that the axial directions A of the electrode bodies 2 are parallel to each other, and are arranged in an arrangement direction B at predetermined intervals. The plurality of electrode bodies 2 are wrapped by a common thin film outer casing 4.

[0095] The film outer casing 4 has, for example, a structure in which two laminated films are laminated. Each laminated film has, for example, a structure in which thermoplastic resin sheets are laminated on both sides of a metal sheet such as aluminum. In addition, the film outer casing 4 has a plurality of accommodating portions 12 and a sealing portion 14. The plurality of accommodating portions 12 are arranged in an arrangement direction B at predetermined intervals. Each accommodating portion 12 is cylindrical and wraps each electrode body 2 to accommodate it. Each accommodating portion 12 is composed of a bag portion provided on the film outer casing 4. The bag portion is a portion that separates the two laminated films from each other. Therefore, each accommodating portion 12 protrudes from the sealing portion 14 along the shape of the side surface of the electrode body 2. In each accommodating portion 12, an electrolyte is accommodated together with the electrode body 2.

[0096] Seal 14 surrounds the periphery of each container 12, sealing it. Seal 14 is formed, for example, from a welded portion of a thermoplastic resin sheet. The welded portion is formed by thermocompression-bonding the periphery of the bag portion of the film exterior 4, fusing the two thermoplastic resin sheets of the laminate film together. Seal 14 seals each container 12 and interconnects the plurality of containers 12.

[0097] In the first electrode lead 8 and the second electrode lead 10, the end portion on the opposite side to the side connected to the electrode body 2 protrudes to the outside of the thin film outer casing 4. In addition, each first electrode lead 8 protrudes to the same side. The sealing portion 14 of this embodiment is further outward than each accommodating portion 12 in the axial direction A, and has a pair of outer edge portions 26 extending across multiple accommodating portions 12. Each first electrode lead 8 protrudes to the outside of the thin film outer casing 4 from one outer edge portion 26. Each second electrode lead 10 protrudes to the outside of the thin film outer casing 4 from the other outer edge portion 26. The interface between each electrode lead and the outer edge portion 26 is sealed by a known sealant.

[0098] The film exterior body 4 is folded between adjacent housing portions 12, zigzagging in the arrangement direction B. That is, the film exterior body 4 extends in a generally zigzag pattern when viewed from the axial direction A. By folding the film exterior body 4 in a zigzag pattern, the spacing between the housing portions 12 in the arrangement direction B can be narrowed compared to the pre-folded state, thereby shortening the length of the power storage device 1 in the arrangement direction B.

[0099] Furthermore, the plurality of housings 12 of this embodiment are arranged so that, when the film exterior body 4 is in a meandering state, their respective centers are aligned on the same straight line as viewed from the axial direction A. This can suppress the size of the power storage device 1 in the orthogonal direction C from increasing in size compared to a case where the plurality of housings 12 are arranged with their respective centers staggered in the orthogonal direction C. Furthermore, the zigzag-curved sealing portion 14 is housed further inward of the housing 12 in the orthogonal direction C. Thus, by folding the film exterior body 4, the size of the power storage device 1 in the orthogonal direction C can be suppressed. Furthermore, in the present disclosure, the centers of the plurality of housings 12 do not necessarily need to be aligned.

[0100] The sealing portion 14 includes a first connecting portion 28 and a second connecting portion 30, which are sandwiched between two adjacent accommodating portions 12 and connect the two accommodating portions 12. The first connecting portion 28 and the second connecting portion 30 are staggered in the arrangement direction B and staggered with each other in the orthogonal direction C. In addition, each connecting portion is longer in the axial direction A and extends parallel to the arrangement direction B. Each connecting portion is sandwiched between the two accommodating portions 12 in the arrangement direction B and is sandwiched between the two outer edge portions 26 in the axial direction A. Each accommodating portion 12 has both ends in the axial direction A sealed by the outer edge portions 26, one end in the arrangement direction B sealed by the first connecting portion 28, and the other end in the arrangement direction B sealed by the second connecting portion 30.

[0101] like Figure 12 As shown, before the outer edge portion 26 is folded, the area of ​​the outer edge portion 26 that is continuous from the housing portion 12, that is, the area that overlaps with the housing portion 12 when viewed from the axial direction A, extends linearly through the center of the housing portion 12 when viewed from the axial direction A and is inclined relative to the arrangement direction B. In addition, in two adjacent housing portions 12, the directions in which the outer edge portion 26 on one housing portion 12 extends are different from those of the outer edge portion 26 on the other housing portion 12. In addition, the outer edge portion 26 on the housing portion 12 and the outer edge portion 26 on the first connecting portion 28 have a predetermined angle with each other, that is, they are connected non-linearly. The outer edge portion 26 on the housing portion 12 and the outer edge portion 26 on the second connecting portion 30 are also connected non-linearly. As a result, the outer edge portion 26 and, therefore, the film outer body 4 meanders in the arrangement direction B.

[0102] The outer edge 26 is as follows Figure 12 As shown, it tilts from the upright state to the orthogonal direction C and becomes Figure 11The flat state is shown. Thus, the size of the power storage device 1 in the axial direction A can be reduced. However, since the outer edge portion 26 is meandering, it will bend randomly if simply tilted in the orthogonal direction C. If the outer edge portion 26 is bent randomly, the number of fold lines formed or the total extension will increase. The film outer body 4 is a component that welds two laminated films, so the film is easily peeled off at the fold line portion. Therefore, it is desirable to minimize the fold lines generated when the outer edge portion 26 is tilted in the orthogonal direction C.

[0103] In contrast, in the power storage device 1 of the present embodiment, the outer edge portion 26 is folded as described below. Figure 13 This is a diagram showing the power storage device 1 as viewed from the axial direction A. Figure 14 (A) and Figure 14 FIG. 1(B) is a perspective view of a portion of the power storage device 1 as viewed from one side C1 in the orthogonal direction C. FIG. Figure 15 (A) and Figure 15 FIG. 1B is a perspective view of a portion of the power storage device 1 as viewed from the other side C2 in the orthogonal direction C. FIG.

[0104] As described above, the sealing portion 14 includes the first connecting portion 28 and the second connecting portion 30. When viewed in the axial direction A, the first connecting portion 28 is offset to one side C1 in the orthogonal direction C relative to the center line L passing through the centers of the plurality of housing portions 12, and extends parallel to the center line L. On the other hand, the second connecting portion 30 is offset to the other side C2 in the orthogonal direction C relative to the center line L, and extends parallel to the center line L.

[0105] The outer edge portion 26 has a first tilted portion 32 and a second tilted portion 34. Figure 13 In the figure, the area indicated by the horizontal dashed line is the first tilting portion 32, and the area indicated by the vertical dashed line is the second tilting portion 34. The first tilting portion 32 is a region continuous from the first connecting portion 28 and the accommodating portion 12. At the first connecting portion 28 and the connection with the accommodating portion 12, it bends toward the second connecting portion 30 in the orthogonal direction C, i.e., the other side C2, starting from the connection. Meanwhile, the second tilting portion 34 is a region continuous from the second connecting portion 30 and the two first tilting portions 32 arranged with the second connecting portion 30 sandwiched therebetween. At the second connecting portion 30 and the connection with the two first tilting portions 32, it bends toward the first connecting portion 28 in the orthogonal direction C, i.e., the one side C1, starting from the connection. The connection between the first tilting portion 32 and the second tilting portion 34 corresponds to a fold line 36 where the outer edge portion 26, which tilts toward the other side C2, folds toward the one side C1. One endpoint of the fold line 36 contacts the second connecting portion 30.

[0106] Specifically, the portion of the outer edge portion 26 on the first connecting portion 28 tilts toward the other side C2 when viewed from the axial direction A, forming a portion of the first tilted portion 32. The portion of the second connecting portion 30 tilts toward the one side C1, forming a portion of the second tilted portion 34. The portion of the accommodating portion 12 tilts toward the other side C2 and then folds obliquely, tilting toward the one side C1. The portion tilted toward the other side C2 forms a portion of the first tilted portion 32, and the portion tilted toward the one side C1 forms a portion of the second tilted portion 34.

[0107] Therefore, the first tilted portion 32 and the second tilted portion 34 overlap each other on the housing portion 12 when viewed from the axial direction A, forming an overlapping portion 38. Figure 13 , the area indicated by the solid oblique lines is the overlapping portion 38. In the overlapping portion 38, the first tilting portion 32 is located closer to the receiving portion 12 than the second tilting portion 34. That is, the second tilting portion 34 overlaps the first tilting portion 32. In addition, the first tilting portion 32 has a concave fold 40 that is embedded between adjacent receiving portions 12. In the first connecting portion 28, the portion that is loosened in the arrangement direction B by tilting toward the other side C2, that is, the portion of the first tilting portion 32 that is left surplus due to the difference in circumference between the inner peripheral edge and the outer peripheral edge, is embedded between the two receiving portions 12, forming the concave fold 40.

[0108] In the above-described embodiment, by folding the outer edge portion 26, the number of fold lines formed when folding the outer edge portion 26 and the total length of the fold lines can be reduced. Furthermore, when viewed from the axial direction A, the second tilted portion 34 of this embodiment is an isosceles trapezoidal shape, with the connection with the second connecting portion 30 (the boundary between the second tilted portion 34 and the second connecting portion 30) as the base and the two fold lines 36 connecting the first tilted portion 32 and the second tilted portion 34 (the connection between the first tilted portion 32 and the second tilted portion 34) as the waist. This further reduces the total length of the fold lines formed by the outer edge portion 26.

[0109] When the outer edge portion 26 is folded in the above-mentioned manner, the following conditions are met. Figure 13As shown, the endpoint of the fold line 36 opposite the second connecting portion 30 is defined as endpoint P1, and the endpoint connecting the second connecting portion 30 is defined as endpoint P2. Furthermore, the connection between the first pouring portion 32 and the accommodating portion 12 is defined as boundary line L1, and the perpendicular line drawn from endpoint P1 to boundary line L1 is defined as perpendicular line L2. Furthermore, the intersection of boundary line L1 and perpendicular line L2 is defined as intersection point P3. Furthermore, the outermost edge of the film outer body 4 is defined as outermost edge L3. The fold line 36 and outermost edge L3 merge at endpoint P1. On both sides of each second connecting portion 30 in the arrangement direction B, a triangle is formed with endpoints P1, endpoint P2, and intersection point P3 as vertices. In this case, the sum of the length from intersection point P3 to endpoint P2 of one triangle, the length of the second connecting portion 30 (the length between the two endpoints P2), and the length from endpoint P2 to intersection point P3 of the other triangle is approximately equal to the length of outermost edge L3 between the two endpoints P1.

[0110] The first electrode leads 8 of the electrode bodies 2 are electrically connected via bus bars 42. The bus bars 42 are strip-shaped conductive members extending in the arrangement direction B. Specifically, Figure 14 As shown in (B), the bus bar 42 is inserted between each housing 12 and each first electrode lead 8 from one side C1. Each first electrode lead 8 is placed on the bus bar 42 and joined to the bus bar 42 by a known joining process such as laser welding. In this way, the plurality of electrode bodies 2 are electrically connected. An insulating sheet may be present between the bus bar 42 and each housing 12. The same applies to electrically connecting the second electrode leads 10 of each electrode body 2.

[0111] In the present embodiment, a plurality of first electrode leads 8 protrude to the same side. Therefore, when each electrode lead is joined to the bus bar 42, all the electrode bodies 2 are connected in parallel to each other. However, the scheme for electrically connecting each electrode body 2 is not particularly limited. For example, the first electrode lead 8 and the second electrode lead 10 may be arranged alternately, and the adjacent first electrode leads 8 and the second electrode leads 10 may be electrically connected. That is, a plurality of electrode bodies 2 may also be connected in series. In addition, the first electrode lead 8 and the second electrode lead 10 of each electrode body 2 may also protrude to the same side as each other in the axial direction A. Thus, the bus bar 42 is arranged only on one side of the axial direction A to perform electrical connection of each electrode body 2. Therefore, the number of connection steps of the energy storage device 1 can be reduced.

[0112] Figure 16 This diagram illustrates an arrangement of multiple power storage devices 1. When combining multiple power storage devices 1 to form a power storage module, the multiple power storage devices 1 are arranged in an orthogonal direction C, as an example. Furthermore, the power storage devices 1 are positioned so that their housings 12 are aligned in the same direction. Furthermore, the first electrode leads 8 of each power storage device 1 are arranged so that they extend toward the same side in the orthogonal direction C. The same applies to the second electrode leads 10.

[0113] Two adjacent power storage devices 1 in the orthogonal direction C are arranged offset from each other in the arrangement direction B so that the axis of the electrode body 2 of one power storage device 1 is located between the axis of the two adjacent electrode bodies 2 in the same power storage device 1. That is, the housing 12 of one power storage device 1 is embedded between the recesses of the two housings 12 of the other power storage device 1. This can reduce the size of the power storage module in the orthogonal direction C. In addition, Figure 16 The middle figure shows two power storage devices 1, but the number of power storage devices 1 constituting the power storage module may be three or more. Figure 16 The two power storage devices 1 shown are positioned so that the first electrode leads 8 protrude to the same side, but may be arranged so that the first electrode leads 8 protrude in opposite directions.

[0114] Figure 17 This is a schematic diagram for explaining the configuration of the electrode leads. Below, the configuration of the electrode leads is described using the example of the first electrode lead 8, but the same applies to the second electrode lead 10. The first electrode lead 8 is bent at the boundary line L1 between the first tilting portion 32 and the accommodating portion 12. Furthermore, when the first electrode lead 8 passes through the overlapping portion 38, it is also bent at the folding line 36. When the first electrode lead 8 is bent, the first electrode lead 8 and the outer edge portion 26 may peel off starting from the bent position, forming a peeling portion 44.

[0115] The more parts that are stacked, the more likely the peeling portion 44 is to be formed. The portion where the first electrode lead 8 and the outer edge portion 26 overlap has a structure in which at least three parts are stacked, specifically, the first electrode lead 8 and two laminated films are stacked. Therefore, the peeling portion 44 is more likely to be formed than the portion where the first electrode lead 8 does not extend. The first electrode lead 8 is bent at two positions as described above, so two peeling portions 44 can be formed along the protruding direction of the first electrode lead 8. When the accommodating portion 12 is connected to the outside of the film outer body 4 via the two peeling portions 44, a path for the contents of the accommodating portion 12 to leak out is formed, and at this position, the sealing of the sealing portion 14 is impaired.

[0116] In this regard, Figure 17As shown, the first electrode lead 8 of the present embodiment is configured to pass through a position offset from the midpoint 36a of the folding line 36 (connecting portion) connecting the first tilting portion 32 and the second tilting portion 34. At the midpoint 36a of the folding line 36, the distance D1 from the boundary line L1 to the folding line 36 is approximately equal to the distance D2 from the folding line 36 to the outermost edge L3 of the film outer casing 4. Therefore, when the first electrode lead 8 passes through the midpoint 36a, the possibility of the above-mentioned leakage path being formed through the two peeling portions 44 that can be formed along the first electrode lead 8 increases. Therefore, by configuring the first electrode lead 8 in a manner offset from the midpoint 36a of the folding line 36, it is possible to suppress the reduction in the sealing performance of the electrode body 2 by folding the outer edge portion 26.

[0117] The closer the folding line 36 is to the second connecting portion 30 than the midpoint 36a, the further it is separated from the outermost edge L3. Therefore, by making the position where the first electrode lead 8 passes through the folding line 36 closer to the second connecting portion 30 than the midpoint 36a, the peeling portion 44 formed around the folding line 36 can be separated from the outermost edge L3. Therefore, the formation of a leakage path can be suppressed. On the other hand, the further the folding line 36 is from the second connecting portion 30 than the midpoint 36a, the further it is from the boundary line L1. Therefore, by making the position where the first electrode lead 8 passes through the folding line 36 further from the second connecting portion 30 than the midpoint 36a, the peeling portion 44 formed around the folding line 36 can be separated from the peeling portion 44 formed around the boundary line L1. Thus, the formation of a leakage path can be suppressed.

[0118] Preferably, the first electrode lead 8 is configured so that at least a portion passes through the outer end region R (the region of the outer 1 / 4) when the folding line 36 is divided into four equal parts. More preferably, the first electrode lead 8 is configured so that the entirety passes through the outer end region R. Thus, the peeling portion 44 formed around the folding line 36 can be separated from the outermost edge L3, or from the peeling portion 44 formed around the boundary line L1. Thus, the formation of a leakage path can be further suppressed. Alternatively, the first electrode lead 8 can be configured so as to pass through the outside of the overlapping portion 38. In this case, the position where the first electrode lead 8 is bent is only the position overlapping with the boundary line L1. Therefore, the formation of a leakage path can be further suppressed. In addition, the peeling portion 44 is not a component that must be formed in the power storage device 1 of the present disclosure (it may also be not formed).

[0119] An example of a method for manufacturing the power storage device 1 will be described below. Figure 18 (A)~ Figure 18 (C) and Figure 19 (A)~ Figure 19 (C) is a process diagram of a method for manufacturing the power storage device 1. First, Figure 18As shown in (A), a first laminate film 20a is prepared. A plurality of semi-cylindrical depressions 18 are pre-formed on the first laminate film 20a. The plurality of depressions 18 are formed, for example, by subjecting the first laminate film 20a to a known process such as stamping. An electrode body 2 is placed on each depression 18. The first electrode lead 8 and the second electrode lead 10 are pre-connected to the electrode body 2. A sealant (not shown) is provided on the first electrode lead 8 and the second electrode lead 10.

[0120] Then, if Figure 18 As shown in (B), the second laminate film 20b overlaps the first laminate film 20a to form a thin film outer body 4. On the second laminate film 20b, a semi-cylindrical recess 18 is provided at a position opposite to each recess 18 of the first laminate film 20a. Therefore, by overlapping the first laminate film 20a and the second laminate film 20b, a bag portion is formed by a pair of recesses 18, in other words, a housing portion 12 is formed. The method of forming the recess 18 in the second laminate film 20b is the same as the method of forming the recess 18 in the first laminate film 20a. When the electrode body 2 is accommodated in the housing portion 12, the front end of the first electrode lead 8 and the front end of the second electrode lead 10 protrude outside the thin film outer body 4.

[0121] Then, if Figure 18 As shown in (C), a portion of the film outer casing 4 is subjected to a heat-compression bonding treatment to form a welded portion 22. The portion of the film outer casing 4 that is not subjected to the heat-compression bonding treatment becomes a non-welded portion 24. The non-welded portion 24 is configured to connect each housing 12 to the outside of the film outer casing 4. In this embodiment, the non-welded portion 24 is provided to connect the protruding side of the first electrode lead 8 among the four sides of each housing 12 to the outside of the film outer casing 4. The remaining three sides of each housing 12 are surrounded by the welded portion 22. The interface between the film outer casing 4 and the second electrode lead 10 is sealed by a sealant.

[0122] Then, if Figure 19 As shown in (A), the electrolyte 16 is injected into each housing portion 12 through the non-welded portion 24. After the electrolyte 16 is injected, as shown in FIG. Figure 19 As shown in (B), the non-welded portion 24 is also subjected to a heat-compression bonding process. As a result, a sealing portion 14 is formed around the entire periphery of each housing portion 12. The interface between the film outer body 4 and the first electrode lead 8 is sealed with a sealant. Next, as shown in FIG. Figure 19 As shown in (C), the film outer casing 4 is bent into a Z-shape. Furthermore, the outer edge portion 26 is folded. Through the above steps, the power storage device 1 is obtained. The outer edge portion 26 is folded, for example, by assigning a jig corresponding to the shape of the first tilted portion 32 from the other side C2, assigning a jig corresponding to the shape of the second tilted portion 34 from one side C1, and punching the outer edge portion 26 using a press.

[0123] The method for manufacturing the electricity storage device 1 is not limited to the above method. For example, a laminate film having a length twice that of the electricity storage device 1 may be used, and the laminate film may be folded in half to wrap each electrode body 2. In addition, if the required amount of electrolyte 16 is small, the electrode spacer may be pre-soaked with electrolyte 16 to omit the need for the electrolyte 16. Figure 19 The electrolyte 16 injection process shown in (A) is performed. Figure 18 In the thermocompression bonding step shown in (C), the entire circumference of each housing portion 12 is subjected to thermocompression bonding to form the sealed portion 14 .

[0124] As described above, the electricity storage device 1 of this embodiment includes: a plurality of cylindrical electrode bodies 2; and a thin film exterior body 4 having a plurality of housings 12 that individually encase the plurality of electrode bodies 2, and a sealing portion 14 that seals each housing 12 and connects the plurality of housings 12 to one another. The thin film exterior body 4 is bent between adjacent housings 12, meandering in the arrangement direction B. The sealing portion 14 includes a first connecting portion 28 and a second connecting portion 30 that are sandwiched between two adjacent housings 12 to connect the two housings 12; and an outer edge portion 26 that extends outward from each housing 12 in the axial direction A of the electrode body 2 and across the plurality of housings 12.

[0125] The first connecting portion 28 and the second connecting portion 30 are arranged alternately in the arrangement direction B of the electrode body 2, and are offset from each other in the orthogonal direction C that is orthogonal to the axial direction A and the arrangement direction B, extending in the arrangement direction B. The outer edge portion 26 has a first tilting portion 32 and a second tilting portion 34. The first tilting portion 32 has a concave fold 40, which is continuous from the first connecting portion 28 and the accommodating portion 12, and is bent toward the second connecting portion 30 in the orthogonal direction C starting from the connection portion with them, and is located between adjacent accommodating portions 12. The second tilting portion 34 is continuous from the second connecting portion 30 and the two first tilting portions 32 arranged with the second connecting portion 30 sandwiched therebetween, and is bent toward the first connecting portion 28 in the orthogonal direction C starting from the connection portion with them. The first tilting portion 32 and the second tilting portion 34 overlap each other on the accommodating portion 12 as viewed from the axial direction A to form an overlapping portion 38.

[0126] When multiple chambers 12 house individual electrode assemblies 2, the generation of gas within the chambers 12 and the expansion of the electrode assemblies 2 during charging and discharging of the electricity storage device 1 may place a significant load on the sealing portion 14. If the sealing portion 14 breaks, connecting the interior of the chamber 12 with the exterior of the film outer casing 4, the electrolyte 16 may leak out of the film outer casing 4. Furthermore, if the sealing portion 14 breaks, connecting adjacent chambers 12, the adjacent electrode assemblies 2 may short-circuit, or the amount of electrolyte 16 may be uneven between the two chambers 12, potentially reducing the power generation performance of the electricity storage device 1.

[0127] Therefore, to ensure the sealing of the electrode assembly 2, it is desirable to increase the area of ​​the sealing portion 14 to improve the strength of the sealing portion 14. However, increasing the size of the sealing portion 14 leads to an increase in the size of the power storage device 1. Furthermore, an increase in the size of the power storage device 1 leads to a decrease in the filling rate of the electrode assembly 2 in the power storage module, that is, the energy density of the power storage module 100. On the other hand, if the sealing portion 14 is reduced in size to increase the energy density of the power storage module, the sealing of the electrode assembly 2 will be compromised.

[0128] In contrast, in the electricity storage device 1 of this embodiment, the film exterior body 4 is folded in a meandering manner in the arrangement direction B. This allows the spacing between adjacent housings 12 to be shortened without reducing the size of the sealing portion 14, thereby shortening the length of the electricity storage device 1 in the arrangement direction B. Furthermore, in the electricity storage device 1 of this embodiment, the outer edge portion 26 of the sealing portion 14, which extends outward from the housing 12 in the axial direction A, is tilted in the orthogonal direction C. This allows the length of the electricity storage device 1 in the axial direction A to be shortened.

[0129] Furthermore, when the outer edge portion 26 meandering in the arrangement direction B is tilted, a first tilting portion 32 and a second tilting portion 34 tilting toward opposite sides in the orthogonal direction C are alternately formed in the arrangement direction B, with portions of the two tilting portions overlapping. Furthermore, a concave fold 40 is provided in the first tilting portion 32. This minimizes fold lines, wrinkles, and deformations that occur when the outer edge portion 26 is folded, thereby suppressing a reduction in the sealing performance of the electrode body 2. Therefore, according to the power storage device 1 of this embodiment, while suppressing a reduction in the sealing performance of the electrode body 2, the power storage device 1 can be miniaturized, thereby achieving an improvement in the mounting efficiency of the power storage device 1, that is, an improvement in the energy density of the power storage module.

[0130] Furthermore, the energy storage device 1 of this embodiment has a bag structure in which multiple electrode assemblies 2 are sealed within a film outer casing 4. This allows for a lighter energy storage module compared to a case where each electrode assembly 2 is individually sealed within an outer can. This significant weight reduction effect is particularly evident when the number of electrode assemblies 2 mounted in an energy storage module increases as the capacity of the module increases.

[0131] Furthermore, the second tilted portion 34 of this embodiment, when viewed from the axial direction A, has an isosceles trapezoidal shape, with the connection with the second connecting portion 30 serving as the base and the two fold lines 36 connecting the first tilted portion 32 and the second tilted portion 34 serving as the waist. This further reduces the total length of the fold lines generated when folding the outer edge portion 26. Consequently, a reduction in the sealing performance of the electrode assembly 2 can be further suppressed.

[0132] Furthermore, the energy storage device 1 of this embodiment includes a first electrode lead 8 and a second electrode lead 10, which are electrically connected to each electrode body 2 and protrude from the outer edge portion 26. Each electrode lead is arranged so as to pass through a position offset from the midpoint 36a of the fold line 36, which connects the first inclined portion 32 and the second inclined portion 34. Furthermore, each electrode lead is arranged so that at least a portion passes through the outer end region R of the fold line 36, which is divided into four equal parts, or passes outside the overlapping portion 38. This further reduces the risk of a reduction in the sealing performance of the electrode body 2 due to the folding of the outer edge portion 26.

[0133] The above is a detailed description of the embodiments of the present disclosure. The aforementioned embodiments only show specific examples when implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and various design changes such as changes, additions, and deletions of constituent elements can be made without departing from the scope of the idea of ​​the invention specified in the claims. The new embodiment with design changes has the effects of the combined embodiment and the deformation. In the aforementioned embodiments, the content that can be subjected to such design changes is emphasized by giving expressions such as "this embodiment" and "in this embodiment", and design changes are allowed even if there is no such expression. In addition, any combination of the constituent elements included in each embodiment is also valid as a scheme of the present disclosure. The hatching marked on the cross section of the accompanying drawings does not limit the material of the object marked with the hatching.

[0134] Industrial applicability

[0135] The present disclosure can be utilized in a power storage device and a power storage module.

[0136] Description of Reference Numerals

[0137] 1. Energy storage device, 2. Electrode assembly, 4. Thin film exterior, 12. Housing, 14. Sealing portion, 14a. First side, 26. Outer edge, 28. First connecting portion, 30. Second connecting portion, 32. First tilting portion, 34. Second tilting portion, 36. Folding line, 36a. Midpoint, 38. Overlapping portion, 40. Concave fold, 100. Energy storage module, 104. Bracket, 112. Side plate.

Claims

1. An electric storage device comprising: A plurality of cylindrical electrode bodies, and a film outer casing having a plurality of housing portions that individually wrap the plurality of electrode bodies, and a sealing portion that seals each housing portion and connects the plurality of housing portions to each other, the film outer casing being bent between adjacent housing portions and meandering in the arrangement direction of the electrode bodies; The sealing portion has: The first connecting portion and the second connecting portion are sandwiched between two adjacent accommodating portions to connect the two accommodating portions, and An outer edge portion is located outside each housing portion in the axial direction of the electrode body and extends across the plurality of housing portions; The first connecting portion and the second connecting portion are staggered in the arrangement direction and extend in the arrangement direction while being staggered in a direction perpendicular to the axial direction and the arrangement direction. The outer edge portion has: The first tilting portion includes a concave folded portion that is continuous from the first connecting portion and the accommodating portion, bends toward the second connecting portion in the orthogonal direction starting from the first connecting portion and the connection portion with the accommodating portion, and is embedded in the concave folded portion between adjacent accommodating portions; and a second tilted portion, continuous from the second connecting portion and the two first tilted portions arranged with the second connecting portion interposed therebetween, and bending toward the first connecting portion in the orthogonal direction starting from the second connecting portion and the connection portion with the two first tilted portions; When viewed from the axial direction, the first tilted portion and the second tilted portion overlap with each other on the accommodation portion to form an overlapping portion.

2. The power storage device according to claim 1, When viewed from the axial direction, the second tilted portion is an isosceles trapezoidal shape having a connection with the second connecting portion as a base and two folding lines at the connection between the first tilted portion and the second tilted portion as waists.

3. The power storage device according to claim 1 or 2, A strip-shaped electrode lead electrically connected to each electrode body and protruding from the outer edge portion is provided. The electrode lead is arranged to pass through a position offset from a midpoint of a fold line that is a connecting portion between the first inclined portion and the second inclined portion.

4. The power storage device according to claim 3, The electrode lead is arranged so that at least a portion thereof passes through an outer end region of the folding line divided into four equal parts, or passes through the outside of the overlapping portion.

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