Power storage device

Abstract

A power storage device 1 is provided with a plurality of cylindrical electrode bodies and a film outer package 4. The film outer package 4 comprises a plurality of containers 12 and a seal 14. The plurality of containers 12 individually encase the plurality of electrode bodies, and the seal 14 seals the containers 12 and connects the plurality of containers 12 to each other. The film outer package 4 extends in a zig-zag manner with bends or curves between adjacent containers 12.

Description

[Technical Field]

[0001] The present disclosure relates to an energy storage device and an energy storage module. [Background technology]

[0002] Conventionally, a power storage module equipped with a plurality of cylindrical power storage devices (e.g., batteries) has been known (see, for example, Patent Document 1). In the power storage module disclosed in Patent Document 1, each power storage device has a cylindrical outer can, and each outer can houses a wound electrode body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-170613 Summary of the Invention [Problem to be solved by the invention]

[0004] Energy storage modules are sometimes used as power sources for vehicles and mobile devices. Therefore, it is desirable to reduce the weight of energy storage modules. One possible method for reducing the weight of an energy storage module is to encase multiple electrode assemblies in a common film exterior while maintaining individual sealing. This allows for an energy storage device having multiple electrode assemblies. In this case, the exterior cans that house each electrode assembly can be eliminated, thereby reducing the weight of the energy storage module.

[0005] When multiple electrode bodies are sealed in a film exterior, high sealing performance is required for each electrode body to ensure the safety and power generation performance of the energy storage module. To achieve high sealing performance for each electrode body, it is desirable to surround the housing of the electrode body with a large-area sealing portion. However, if the area of ​​the sealing portion is large, the distance between adjacent electrode bodies increases, the external dimensions of the energy storage device increase, and the energy density of the energy storage module may decrease.

[0006] The present disclosure has been made in light of these circumstances, and one of its objectives is to provide a technique for improving the energy density of an electricity storage module while suppressing deterioration in the sealing performance of an electrode assembly. [Means for solving the problem]

[0007] One aspect of the present disclosure is an electricity storage device that includes a plurality of cylindrical electrode assemblies, a plurality of housing sections that individually encase the plurality of electrode assemblies, and a film exterior body that has sealing sections that seal each housing section and connect the plurality of housing sections to one another, and that bends or curves between adjacent housing sections and extends in a zigzag pattern.

[0008] Another aspect of the present disclosure is an electric storage module including a plurality of the electric storage devices according to the above aspect and a holder that holds the plurality of electric storage devices.

[0009] Another aspect of the present disclosure is an energy storage device. This energy storage device includes a plurality of cylindrical electrode assemblies, a plurality of housing sections that individually encase the plurality of electrode assemblies, and a film exterior body that has a sealing section that seals each housing section and connects the plurality of housing sections to one another, and that folds between adjacent housing sections and meanders in the arrangement direction of the electrode assemblies. The sealing section has first and second connecting sections that are sandwiched between two adjacent housing sections and connect the two housing sections, and an outer edge that extends across the plurality of housing sections outside each housing section in the axial direction of the electrode assemblies. The first and second connecting sections are arranged alternately in the arrangement direction of the electrode assemblies and extend in the arrangement direction while being offset from each other in an orthogonal direction perpendicular to the axial direction and the arrangement direction. The outer edge portion has a first inclined portion that continues from the first connecting portion and the storage portion, bends in an orthogonal direction from the connection portion between the first connecting portion and the storage portion to the second connecting portion side, and has a valley fold that fits between adjacent storage portions, and a second inclined portion that continues from the second connecting portion and two first inclined portions that are lined up on either side of the second connecting portion, bends in an orthogonal direction from the connection portion between the second connecting portion and the two first inclined portions to the first connecting portion side. The first inclined portion and the second inclined portion overlap each other on the storage portion when viewed from the axial direction to form an overlapping portion.

[0010] Any combination of the above components, and conversion of the expression of the present disclosure into a method, device, system, etc., are also valid aspects of the present disclosure. [Effects of the Invention]

[0011] According to the present disclosure, it is possible to improve the energy density of the energy storage module while suppressing deterioration in the sealing performance of the electrode body. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view of an electricity storage device according to a first embodiment. [Figure 2] Fig. 2(A) is a schematic diagram of the electricity storage device as viewed from the axial direction, and Fig. 2(B) is a schematic diagram of the electricity storage device as viewed from a second direction. [Figure 3] 3(A) to 3(C) are process diagrams of a method for manufacturing an electricity storage device. [Figure 4] 4(A) to 4(C) are process diagrams of a method for manufacturing an electricity storage device. [Figure 5] FIG. 1 is a perspective view of an electricity storage module according to a first embodiment. [Figure 6] FIG. 2 is an exploded perspective view of the electricity storage module. [Figure 7] FIG. 2 is an enlarged perspective view of a portion of the power storage module. [Figure 8] FIG. 10 is a perspective view of an electricity storage module according to a second embodiment. [Figure 9] FIG. 2 is an exploded perspective view of the electricity storage module. [Figure 10] FIG. 2 is a cross-sectional view of the storage module. [Figure 11] FIG. 11 is a perspective view of an electricity storage device according to a third embodiment. [Figure 12] FIG. 2 is a perspective view of the power storage device before the outer edge portion is folded. [Figure 13] FIG. 2 is a view of the electricity storage device as seen from the axial direction. [Figure 14] 14(A) and 14(B) are perspective views of a part of the electricity storage device as viewed from one side in the orthogonal direction. [Figure 15] 15(A) and 15(B) are perspective views of a part of the electricity storage device as viewed from the other side in the orthogonal direction. [Figure 16] FIG. 2 is a diagram showing an arrangement of a plurality of power storage devices. [Figure 17] FIG. 2 is a schematic diagram for explaining the arrangement of electrode leads. [Figure 18] 18(A) to 18(C) are process diagrams of a method for manufacturing an electricity storage device. [Figure 19] 19(A) to 19(C) are process diagrams of a method for manufacturing an electricity storage device. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure will be described below with reference to preferred embodiments and drawings. The embodiments are illustrative and do not limit the present disclosure, and all features and combinations thereof described in the embodiments are not necessarily essential to the present disclosure. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. The scale and shape of each part shown in each drawing are set for convenience to facilitate explanation and should not be interpreted as limiting unless otherwise specified. Furthermore, when terms such as "first" and "second" are used in this specification or claims, unless otherwise specified, these terms do not indicate any order or importance, but are intended to distinguish one configuration from another. Furthermore, some components that are not important for explaining the embodiments are omitted from each drawing.

[0014] (Embodiment 1) FIG. 1 is a perspective view of an energy storage device 1 according to a first embodiment. FIG. 2(A) is a schematic diagram of the energy storage device 1 as viewed from an axial direction A. FIG. 2(B) is a schematic diagram of the energy storage device 1 as viewed from a second direction C. For ease of explanation, FIG. 2(B) also illustrates the inside of a film exterior body 4. The state before the film exterior body 4 is folded is illustrated by a dashed line. In this embodiment, the direction in which the spiral axis of the electrode body 2 extends is referred to as an axial direction A, the direction in which the multiple electrode bodies 2 are arranged is referred to as a first direction B (sometimes referred to as an arrangement direction B in this disclosure), and the direction perpendicular to the axial direction A and the first direction B is referred to as a second direction C (sometimes referred to as an orthogonal direction C in this disclosure).

[0015] The power storage device 1 of this embodiment is, for example, a rechargeable secondary battery such as a lithium ion battery, a nickel-metal hydride 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 film exterior body 4. The power storage device 1 of this embodiment includes eight electrode bodies 2, but the number is not particularly limited as long as it is two or more.

[0016] Each electrode body 2 is cylindrical and has a spirally wound structure in which a strip-shaped first electrode plate and a strip-shaped second electrode plate are stacked with an inter-electrode separator sandwiched between them. For 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 the corresponding electrode plate. The multiple electrode bodies 2 are positioned so that the axial directions A of the electrode bodies 2 are parallel to each other, and are arranged at predetermined intervals in a first direction B. The multiple electrode bodies 2 are wrapped in a common film exterior body 4.

[0017] The film exterior body 4 has a structure in which, for example, two laminate films are stacked. Each laminate film has a structure in which a thermoplastic resin sheet is laminated on both sides of a metal sheet, such as aluminum. The film exterior body 4 also has multiple storage sections 12 and a sealing section 14. The multiple storage sections 12 are arranged at predetermined intervals in the first direction B. Each storage section 12 is cylindrical and individually encloses and stores each electrode assembly 2. Each storage section 12 is formed by a bag section provided in the film exterior body 4. The bag section is a portion where two laminate films are spaced apart from each other. Therefore, each storage section 12 protrudes from the sealing section 14 in accordance with the shape of the side surface of the electrode assembly 2. In other words, each storage section 12 bulges in the thickness direction of the film exterior body 4. Each storage section 12 stores an electrolyte 16 together with the electrode assembly 2.

[0018] The sealing portion 14 surrounds the outer periphery of each storage portion 12 to seal it. The sealing portion 14 is formed, for example, by a welded portion of a thermoplastic resin sheet. The welded portion is obtained by subjecting the outer periphery of the bag portion of the film exterior body 4 to a thermocompression treatment, thereby welding the thermoplastic resin sheets of the two laminate films together. The sealing portion 14 seals each storage portion 12 and also connects the multiple storage portions 12 to one another.

[0019] The ends of the first electrode lead 8 and the second electrode lead 10 opposite to the end connected to the electrode body 2 protrude outside the film exterior body 4. The interface between each electrode lead and the film exterior body 4 is sealed with a known sealant. In this embodiment, the first electrode lead 8 and the second electrode lead 10 connected to each electrode body 2 protrude on opposite sides of each other in the axial direction A. Furthermore, each first electrode lead 8 protrudes on the same side. Note that the first electrode lead 8 and the second electrode lead 10 may also protrude on the same side in the axial direction A.

[0020] The film exterior body 4 bends or curves between adjacent storage sections 12 and extends in a zigzag pattern. That is, the film exterior body 4 snakes in the first direction B. By folding the film exterior body 4 in a zigzag pattern, the spacing between the storage sections 12 in the first direction B can be narrower than in the state before folding, thereby shortening the length of the energy storage device 1 in the first direction B. Furthermore, the multiple storage sections 12 in this embodiment are arranged so that their centers are aligned on the same line as viewed from the axial direction A when the film exterior body 4 extends in a zigzag pattern. This prevents the size of the energy storage device 1 in the second direction C from increasing compared to when multiple storage sections 12 are arranged so that their centers are offset in the second direction C. Furthermore, each storage section 12 in this embodiment protrudes outward in the second direction C from the sealing section 14, which is bent in a zigzag pattern. In other words, the sealing portion 14, which is folded in a zigzag shape, is located inside the storage portion 12 in the second direction C. This makes it possible to reduce the dimension of the energy storage device 1 in the first direction B while further preventing the dimension of the energy storage device 1 in the second direction C from increasing when the film exterior body 4 is folded. Note that in the present disclosure, the centers of the multiple storage portions 12 do not necessarily have to be located on the same straight line.

[0021] Specifically, the sealing portion 14 has a pair of first sides 14a and a pair of second sides 14b that surround the periphery of each storage portion 12. The pair of first sides 14a are aligned in the axial direction A, sandwiching each storage portion 12 therebetween, and seal the end of each storage portion 12 in the axial direction A. In this embodiment, the first sides 14a extend linearly through the center of the storage portion 12 when viewed from the axial direction A. The pair of second sides 14b are aligned in a direction perpendicular to the axial direction A, sandwiching each storage portion 12 therebetween, and extend in the axial direction A to connect the pair of first sides 14a.

[0022] The two second sides 14b located between two adjacent storage sections 12 are connected to each other at a predetermined angle θ, i.e., non-linearly. The direction in which the connection between the two second sides 14b bends or curves alternates among the multiple connection sections aligned in the first direction B. As a result, the film exterior body 4 extends in a zigzag pattern in the first direction B. Note that when the connection section is curved, the angle θ formed by the two second sides 14b is, for example, the angle at which an extension line of the first side 14a corresponding to (contacting) one storage section 12 intersects with an extension line of the first side 14a corresponding to the other storage section 12.

[0023] Preferably, the connection portion is curved. This prevents the film exterior body 4 from breaking or the two laminate films from peeling off at the connection portion, which would otherwise reduce the sealing performance of each storage section 12. Preferably, the film exterior body 4 is bent or curved so that the two first sides 14a corresponding to two adjacent storage sections 12 extend in directions that intersect with each other. In other words, the amount of fold (angle) or bend (angle) of the two second sides 14b from a straight state is less than 180°, and the two adjacent first sides 14a extend non-parallel to each other.

[0024] This makes it easier to prevent the sealing portion 14 from protruding outward from the accommodating portion 12 in the second direction C, compared to when the two first side portions 14a are bent or curved until they are parallel. Alternatively, the amount of protrusion of the sealing portion 14 can be reduced. Therefore, the size of the energy storage device 1 in the second direction C can be prevented from increasing. More preferably, the angle θ formed by the two second side portions 14b is an obtuse angle (more than 90° and less than 180°). In other words, the amount of folding (angle amount) or bending (angle amount) is more than 0° and less than 90°. This reduces stress on the connecting portion. Therefore, it is possible to further prevent the sealing portion 14 from breaking or the two laminate films from peeling off at the connecting portion, which could lead to a deterioration in the sealing performance of each accommodating portion 12.

[0025] An example of a method for manufacturing the energy storage device 1 is shown below. FIGS. 3(A) to 3(C) and 4(A) to 4(C) are process diagrams of the method for manufacturing the energy storage device 1. First, as shown in FIG. 3(A), a first laminate film 20a is prepared. A plurality of semi-cylindrical depressions 18 are formed in advance in the first laminate film 20a. The depressions 18 are formed, for example, by subjecting the first laminate film 20a to a known process such as press working. An electrode body 2 is placed in each depression 18. A first electrode lead 8 and a second electrode lead 10 are connected to the electrode body 2 in advance. A sealant (not shown) is provided in the first electrode lead 8 and the second electrode lead 10.

[0026] 3(B), the second laminate film 20b is then superimposed on the first laminate film 20a to form the film exterior housing 4. The second laminate film 20b has semi-cylindrical depressions 18 formed in positions facing the depressions 18 in the first laminate film 20a. Therefore, when the first laminate film 20a and the second laminate film 20b are superimposed, the pair of depressions 18 form the housing section 12. The method for forming the depressions 18 in the second laminate film 20b is the same as the method for forming the depressions 18 in the first laminate film 20a. With the electrode body 2 housed in the housing section 12, the tip of the first electrode lead 8 and the tip of the second electrode lead 10 protrude outside the film exterior housing 4.

[0027] Next, as shown in FIG. 3(C), a thermocompression process is performed on a portion of the film exterior body 4 to form a welded portion 22. The portion of the film exterior body 4 that is not subjected to the thermocompression process becomes a non-welded portion 24. The non-welded portion 24 is arranged so as to connect each housing section 12 to the outside of the film exterior body 4. In the present embodiment, the non-welded portion 24 is provided so as to connect one of the four sides of each housing section 12 from which the first electrode lead 8 protrudes to the outside of the film exterior body 4. The remaining three sides of each housing section 12 are surrounded by the welded portion 22. The interface between the film exterior body 4 and the second electrode lead 10 is sealed with a sealant.

[0028] Next, as shown in FIG. 4(A), electrolyte 16 is poured into each housing section 12 through the non-welded sections 24. After the electrolyte 16 is poured, thermocompression bonding is also performed on the non-welded sections 24, as shown in FIG. 4(B). As a result, a sealing section 14 is formed that surrounds the entire periphery of each housing section 12. The interface between the film exterior body 4 and the first electrode lead 8 is sealed with a sealant. Next, as shown in FIG. 4(C), the film exterior body 4 is folded in a zigzag shape. Through the above steps, the electricity storage device 1 is obtained.

[0029] The manufacturing method of the energy storage device 1 is not limited to the above. For example, each electrode body 2 may be wrapped in a single laminate film having twice the length of the energy storage device 1, which is folded in half. Furthermore, when the required amount of electrolyte solution 16 is small, the step of injecting the electrolyte solution 16 shown in FIG. 4(A) can be omitted by pre-impregnating the inter-electrode separator with the electrolyte solution 16. In this case, in the thermocompression bonding step shown in FIG. 3(C), the entire periphery of each housing portion 12 is subjected to thermocompression bonding to form the sealing portion 14.

[0030] The energy storage device 1 of this embodiment can be incorporated into an energy storage module 100 described below. Fig. 5 is a perspective view of the energy storage module 100 according to the first embodiment. Fig. 6 is an exploded perspective view of the energy storage module 100. Fig. 7 is an enlarged perspective view of a portion of the energy storage module 100.

[0031] The energy storage module 100 includes a plurality of energy storage devices 1, a separator 102, a holder 104, an insulating plate 106, and a bus bar 108. The energy storage module 100 of the present embodiment includes eight energy storage devices 1, but the number is not particularly limited as long as it is two or more.

[0032] The plurality of energy storage devices 1 are aligned in the second direction C with their respective housing sections 12 aligned in the same direction. The plurality of energy storage devices 1 are divided into pairs of units 110. The number of energy storage devices 1 constituting a unit 110 is not limited to two.

[0033] In each unit 110, the two energy storage devices 1 are arranged offset from each other in the first arrangement direction B so that the axis of the electrode body 2 of one energy storage device 1 is located between the axes of two adjacent electrode bodies 2 of the other energy storage device 1. In other words, the accommodation section 12 of one energy storage device 1 fits into the valley between the two accommodation sections 12 of the other energy storage device 1. This makes it possible to reduce the dimension of each unit 110 in the second direction C.

[0034] In each unit 110, a separator 102 is disposed between the two energy storage devices 1. The separator 102 is also called an insulating spacer, for example, and is used to electrically insulate two adjacent energy storage devices 1, hold the energy storage devices 1 that it abuts against, and accommodate assembly tolerances for multiple energy storage devices 1. The separator 102 may be, for example, a corrugated plate with repeated concave and convex portions in the first direction B, or a plate material that is thicker than the corrugated plate and has multiple concave portions arranged in the first direction B on both sides. The separator 102 is made of, for example, an insulating resin. Examples of resins that may be used to form the separator 102 include thermoplastic resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and Noryl (registered trademark) resin (modified PPE). The separator 102 may also be made of an elastic material such as polyurethane, a silica-based insulating material, or the like. As long as the insulating state between the power storage devices 1 can be maintained, the separator 102 may be made of a metal such as aluminum, an aluminum alloy, or steel.

[0035] The multiple energy storage devices 1 are held by multiple holders 104. Each holder 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 protruding in a second direction C from both ends of the side plate 112 in the first direction B. The pair of protrusions 114 face each other in the first direction B. Therefore, the holder 104 has a generally U-shape that is long in the first direction B. The holder 104 is oriented so that the main surface of the side plate 112 faces the second direction C and the main surfaces of the protrusions 114 face the first direction B.

[0036] As an example, each holder 104 is made of a single plate material. The side plate 112 and the pair of protrusions 114 can be formed by bending both ends of a metal plate. Note that the holder 104 may be made of resin as long as a predetermined level of rigidity is obtained. Alternatively, the holder 104 may be formed by joining the side plate 112 and the protrusions 114, which are separate from each other. Examples of metals used for the holder 104 include aluminum, aluminum alloys, steel, etc. Examples of resins used for the holder 104 include thermoplastic resins such as polypropylene (PP), polybutylene terephthalate (PBT), polycarbonate (PC), and Noryl (registered trademark) resin (modified PPE); and fiber-reinforced plastics (FRP) including carbon fiber reinforced plastics and glass fiber reinforced plastics.

[0037] Each holder 104 is assembled to each unit 110 in a one-to-one relationship. Each unit 110 is surrounded on three sides in the first direction B and the second direction C by the holder 104. The side plate 112 covers one surface of the unit 110 in the second direction C. The pair of protrusions 114 cover both surfaces of the unit 110 in the first direction B. As an example, the side plate 112 is fixed to the opposing energy storage device 1 with an adhesive. The adhesive is preferably an insulating adhesive. An insulating sheet (not shown) may be interposed between the unit 110 and the holder 104.

[0038] The units 110 are arranged in the second direction C with the holders 104 assembled thereto. At this time, the units 110 are arranged so that the exposed surfaces not covered by the holders 104 face the same direction. With the units 110 arranged, the exposed surfaces of the units 110 are covered by the side plates 112 of the holders 104 assembled to the adjacent units 110 and fixed with an adhesive. As a result, each unit 110 is sandwiched between the pair of side plates 112 in the second direction C. Furthermore, the side plate 112 located between the two units 110 is sandwiched between the two energy storage devices 1.

[0039] Each protrusion 114 has a tip end 114a and a base end 114b. The base end 114b is interposed between the side plate 112 and the tip end 114a. The tip end 114a is offset from the base end 114b in a direction away from the unit 110. Therefore, the distance between the pair of protrusions 114 is wider on the tip end 114a side than on the base end 114b side. Each tip end 114a protrudes to a position where it overlaps with the base end 114b of the adjacent holder 104 when viewed from the first direction B.

[0040] That is, when the multiple units 110 are arranged in the second direction C, the side plates 112 and the pair of base ends 114b of one holder 104 enter between the pair of tip ends 114a of the other holder 104 in two adjacent holders 104. Then, a known joining process such as laser welding is performed on the portion where the tip end 114a of one holder 104 and the base end 114b of the other holder 104 overlap, forming a joint 116. As a result, the holders 104 are connected to each other, and the multiple power storage devices 1 are held by the multiple holders 104.

[0041] The side plate 112 has a plurality of recesses 112a aligned in the first direction B. Each recess 112a is groove-shaped and extends in the axial direction A. When the holder 104 is assembled to the unit 110, each of the accommodation sections 12 of the power storage device 1 facing the side plate 112 fits into each recess 112a. As a result, the side plate 112 extends along the curved surface of each accommodation section 12. This makes it possible to hold the power storage device 1 more stably. In particular, it is possible to restrict displacement of the power storage device 1 in the first direction B.

[0042] Furthermore, the side plate 112 of this embodiment has a corrugated plate shape with repeated concave and convex portions in the first direction B. That is, when viewed from one main surface side, a plurality of concave portions 112a and a plurality of convex portions 112b are alternately arranged in the first direction B. Therefore, the housing portions 12 of the power storage devices 1 on both sides of the side plate 112 can be fitted into the side plate 112. Specifically, with regard to the concave portions 112a and the convex portions 112b when the side plate 112 is viewed from one main surface side, each housing portion 12 of one power storage device 1 fits into each of the concave portions 112a. Furthermore, each of the convex portions 112b (which become concave portions when viewed from the opposite side) fits into each of the housing portions 12 of the other power storage device 1 from the back side. This further improves the stability of each power storage device 1 in the power storage module 100.

[0043] The unit 110 located at one end in the second direction C has no other units 110 on the exposed surface side. Therefore, an end holder 105 is assembled to the exposed surface of the unit 110. The end holder 105 has the same shape as the holder 104, except that the protruding portion 114 protrudes in the opposite direction to the holder 104 and the protruding portion 114 does not have a tip portion 114a.

[0044] With the multiple units 110 connected together, bus bars 108 are placed on both sides of the multiple units 110 in the axial direction A via insulating plates 106. The first electrode lead 8 and the second electrode lead 10 of each energy storage device 1 are electrically connected to the bus bars 108. For example, each electrode lead is joined to the bus bars 108 by a known joining process such as laser welding. By interposing the insulating plates 106 between the units 110 and the bus bars 108, electrical connection between each energy storage device 1 and the bus bars 108 at portions other than the electrode leads can be suppressed. The insulating plates 106 may be any insulator having a predetermined hardness, and may be made of the same material as the separators 102 or another material.

[0045] In this embodiment, the two energy storage devices 1 in each unit 110 are oriented so that the first electrode leads 8 protrude to the same side. Furthermore, the units 110 are oriented so that the protruding directions of the first electrode leads 8 are staggered. Therefore, when the electrode leads are joined to the bus bar 108, the electrode bodies 2 in each unit 110 are connected in parallel to each other, and the units 110 are connected in series to each other.

[0046] The manner of electrical connection of each electrode body 2 is not particularly limited. For example, in each energy storage device 1, the first electrode leads 8 and the second electrode leads 10 may be arranged alternately, and adjacent first electrode leads 8 and second electrode leads 10 may be electrically connected. That is, in each energy storage device 1, a plurality of electrode bodies 2 may be connected in series. Also, in each unit 110, two energy storage devices 1 may be connected in series. Furthermore, all of the electrode bodies 2 mounted in the energy storage module 100 may be connected in series or in parallel.

[0047] Furthermore, the first electrode lead 8 and the second electrode lead 10 may protrude to the same side in the axial direction A. This allows electrical connection of the electrode bodies 2 simply by arranging the insulating plate 106 and the bus bar 108 on only one side of the energy storage module 100. This allows the number of parts and assembly steps for the energy storage module 100 to be reduced.

[0048] As described above, the energy storage device 1 according to this embodiment includes a plurality of cylindrical electrode bodies 2, a plurality of housing sections 12 that individually encase the plurality of electrode bodies 2, and a film exterior body 4 that seals each housing section 12 and has sealing sections 14 that connect the plurality of housing sections 12 to one another. The film exterior body 4 bends or curves between adjacent housing sections 12 and extends in a zigzag pattern. The energy storage module 100 according to this embodiment also includes a plurality of energy storage devices 1 and a holder 104 that holds the plurality of energy storage devices 1.

[0049] When the electrode bodies 2 are individually housed in multiple housing sections 12, a large load may be placed on the sealing section 14 due to gas generation in the housing sections 12 and swelling of the electrode bodies 2 as the energy storage device 1 is charged and discharged. If the sealing section 14 is damaged and connects the inside of the housing section 12 with the outside of the film exterior body 4, there is a risk of the electrolyte solution 16 leaking out of the film exterior body 4. Furthermore, if the sealing section 14 is damaged and connects adjacent housing sections 12, the adjacent electrode bodies 2 may be short-circuited or the amount of electrolyte solution 16 may be uneven in the two housing sections 12, which may reduce the power generation performance of the energy storage device 1.

[0050] For this reason, it is desirable to increase the area of ​​the sealing portion 14 and increase the strength of the sealing portion 14 in order to ensure the sealing performance of the electrode assembly 2. In particular, in recent years, there has been a trend toward higher capacity for the energy storage device 1, and as the capacity increases, the amount of expansion of the electrode assembly 2 also tends to increase. Therefore, there is an increasing need to increase the strength of the sealing portion 14. However, an increase in the size of the sealing portion 14 leads to an increase in the size of the energy storage device 1. Furthermore, an increase in the size of the energy storage device 1 leads to a decrease in the packing rate of the electrode assembly 2 in the energy storage module 100, that is, a decrease in the energy density of the energy storage module 100. On the other hand, if the sealing portion 14 is made smaller in order to increase the energy density of the energy storage module 100, the sealing performance of the electrode assembly 2 is sacrificed.

[0051] In contrast, in the energy storage device 1 according to the present embodiment, the film exterior body 4 is folded in a zigzag pattern. This allows the distance between adjacent housing sections 12, and therefore the length of the energy storage device 1, to be shorter than when the film exterior body 4 is not folded, without reducing the size of the sealing section 14. As a result, it is possible to increase the number of electrode assemblies 2 mounted in the energy storage module 100, or to reduce the size of the energy storage module 100 without reducing the number of electrode assemblies 2 mounted. In other words, according to the present embodiment, it is possible to improve the energy density of the energy storage module 100 while suppressing a deterioration in the sealing performance of the electrode assemblies 2.

[0052] Furthermore, because the multiple electrode bodies 2 are sealed in the film exterior body 4 to form a pouch structure, the weight of the energy storage module 100 can be reduced compared to when each electrode body 2 is individually sealed in an exterior can. In particular, when the number of electrode bodies 2 mounted in the energy storage module 100 increases as the capacity of the energy storage module 100 increases, a significant weight reduction effect can be achieved.

[0053] Furthermore, the sealing portion 14 of the present 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. The film exterior body 4 is bent or curved so that the two first side portions 14a corresponding to two adjacent housing portions 12 extend in directions that intersect with each other. This makes it easier to prevent the sealing portion 14 from protruding outward from 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, the energy storage device 1 can be prevented from becoming larger in size in the second direction C, and the energy density of the energy storage module 100 can be further increased.

[0054] Moreover, the holder 104 of this embodiment has side plates 112 extending in the arrangement direction of the plurality of accommodating sections 12 (first direction B). The side plates 112 have a plurality of recesses 112a aligned in the first direction B, and each accommodating section 12 fits into each recess 112a. This makes it possible to more stably hold the energy storage devices 1. Therefore, the electrical connection state between each energy storage device 1 and the bus bar 108 can be more stably maintained, and damage to each energy storage device 1 can be further suppressed. This makes it possible to improve the power generation performance and safety of the energy storage module 100.

[0055] Furthermore, the side plate 112 of this embodiment is corrugated with repeated recesses and projections in the first direction B, and is sandwiched between two energy storage devices 1. When viewed from one main surface, each of the accommodation sections 12 of one energy storage device 1 fits into each of the recesses 112a, and when viewed from the main surface, each of the accommodation sections 12 of the other energy storage device 1 fits from the back surface into each of the protrusions 112b. This can further improve the stability of each energy storage device 1 in the energy storage module 100.

[0056] (Embodiment 2) Except for the holding structure of the energy storage device 1, the second embodiment has a common configuration with the first embodiment. The following description of the second embodiment will focus on configurations that are different from those of the first embodiment, and common configurations will be explained briefly or omitted. Fig. 8 is a perspective view of an energy storage module 100 according to the second embodiment. Fig. 9 is an exploded perspective view of the energy storage module 100. Fig. 10 is a cross-sectional view of the energy storage module 100.

[0057] The energy storage module 100 of this embodiment includes multiple energy storage devices 1, a holder 104, and a bus bar 108. The number of energy storage devices 1 included in the energy storage module 100 and the number of electrode bodies 2 included in the energy storage device 1 are not limited to those shown in the drawings. Each energy storage device 1 includes multiple electrode bodies 2 and a film exterior body 4. A first electrode lead 8 and a second electrode lead 10 protrude from each electrode body 2. The film exterior body 4 has multiple housing sections 12 and a sealing section 14. The film exterior body 4 bends or curves between adjacent housing sections 12 and extends in a zigzag pattern.

[0058] The multiple energy storage devices 1 are oriented so that their respective housing sections 12 are aligned in the same direction and are arranged in the second direction C. Two adjacent energy storage devices 1 are arranged offset in the first direction B so that the housing section 12 of one energy storage device 1 fits into the gap between the two housing sections 12 of the other energy storage device 1.

[0059] The plurality of energy storage devices 1 are held by a holder 104. The holder 104 of the present embodiment is composed of a first plate 118 and a second plate 120. The first plate 118 and the second plate 120 are plate-like bodies extending in a first direction B and a second direction C, and sandwich the plurality of energy storage devices 1 in the axial direction A. The materials constituting the first plate 118 and the second plate 120 are the same as those of the holder 104 of the first embodiment.

[0060] A plurality of support portions 122, which are cylindrical recesses with bottoms, are provided on the surfaces of the first plate 118 and the second plate 120 facing the energy storage device 1. The plurality of support portions 122 are arranged so as to overlap with the accommodation portions 12 of the respective energy storage devices 1 in the axial direction A, and the end of each accommodation portion 12 in the axial direction A fits into each support portion 122. As an example, each plate and the plurality of energy storage devices 1 are fixed with an adhesive. Note that a plurality of pillars (not shown) may be interposed between the first plate 118 and the second plate 120 to connect the plurality of pillars to each plate.

[0061] Furthermore, the first plate 118 and the second plate 120 are provided with a plurality of slits 124 that penetrate each plate in the axial direction A and extend in a zigzag pattern in the first direction B. Each slit 124 extends across the plurality of supports 122 while dividing the bottom of each support portion 122 and connecting adjacent support portions 122. The plurality of slits 124 are arranged in the axial direction A so as to overlap with the sealing portions 14 of each power storage device 1, and the end portions (including the first side portions 14a) of each sealing portion 14 in the axial direction A are inserted into the slits 124. This causes the first electrode lead 8 and the second electrode lead 10 of each power storage device 1 to protrude outside the holder 104. Note that only the first electrode lead 8 and the second electrode lead 10 may be inserted into the slits 124.

[0062] Furthermore, a plurality of bus bar mounting surfaces 126 are provided on the surfaces of first plate 118 and second plate 120 facing away from energy storage device 1. Therefore, holder 104 of the present embodiment also functions as insulating plate 106 of embodiment 1. Each bus bar mounting surface 126 is disposed between two slits 124 aligned in second direction C.

[0063] When the first plate 118 and the second plate 120 are assembled to the plurality of energy storage devices 1 and the bus bar 108 is placed on the bus bar mounting 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 the present embodiment, all of the first electrode leads 8 protrude to the same side. Therefore, when each electrode lead is joined to the bus bar 108, all of the electrode bodies 2 are connected in parallel. Note that, as in the first embodiment, the manner of electrical connection of each electrode body 2 is not particularly limited. Furthermore, the shape of the bus bar 108 is not particularly limited. For example, multiple bus bars connecting adjacent electrode bodies 2 in series may be arranged in the first direction B.

[0064] Although holder 104 of the present embodiment has first plate 118 and second plate 120, it may have only one of the plates. For example, by increasing the dimension of one of the plates in axial direction A and providing deeper support portion 122, it is possible to hold multiple electricity storage devices 1 with only that one plate.

[0065] This embodiment also makes it possible to improve the energy density of the energy storage module 100 while suppressing deterioration in the sealing performance of the electrode body 2. Furthermore, compared to the first embodiment, it is possible to reduce the number of parts and assembly steps of the energy storage module 100. Note that, according to the first embodiment, it becomes possible to change the number of energy storage devices 1 mounted in the energy storage module 100 more easily than in this embodiment.

[0066] (Embodiment 3) Fig. 11 is a perspective view of an energy storage device 1 according to embodiment 3. Fig. 12 is a perspective view of the energy storage device 1 before the outer edge portion 26 is folded. Note that in Fig. 11, some of the electrode bodies 2 are illustrated by dashed lines. In this embodiment, the direction in which the spiral axis of the electrode body 2 extends is referred to as axial direction A, the direction in which the multiple electrode bodies 2 are arranged is referred to as arrangement direction B, and the direction perpendicular to the axial direction A and arrangement direction B is referred to as orthogonal direction C.

[0067] The power storage device 1 of this embodiment is, for example, a rechargeable secondary battery such as a lithium ion battery, a nickel-metal hydride 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 film exterior body 4. The power storage device 1 of this embodiment includes eight electrode bodies 2, but the number is not particularly limited as long as it is two or more.

[0068] Each electrode body 2 is cylindrical, and has a spirally wound structure in which a strip-shaped first electrode plate and a strip-shaped second electrode plate are stacked with an inter-electrode separator sandwiched between them. 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 and elongated in one direction), and one end of each is welded to the corresponding electrode plate. The multiple electrode bodies 2 are oriented so that the axial directions A of the electrode bodies 2 are parallel to each other, and are arranged at predetermined intervals in an arrangement direction B. The multiple electrode bodies 2 are wrapped in a common film exterior body 4.

[0069] The film exterior body 4 has a structure in which, for example, two laminate films are stacked. Each laminate film has a structure in which a thermoplastic resin sheet is laminated on both sides of a metal sheet, such as aluminum. The film exterior body 4 also has multiple storage sections 12 and a sealing section 14. The multiple storage sections 12 are arranged at predetermined intervals in the arrangement direction B. Each storage section 12 is cylindrical and individually encloses and stores each electrode body 2. Each storage section 12 is formed by a bag section provided in the film exterior body 4. The bag sections are portions of the two laminate films that are spaced apart from each other. Therefore, each storage section 12 protrudes from the sealing section 14 along the shape of the side surface of the electrode body 2. Each storage section 12 stores an electrolyte together with the electrode body 2.

[0070] The sealing portion 14 surrounds the outer periphery of each storage portion 12 to seal it. The sealing portion 14 is formed, for example, by a welded portion of a thermoplastic resin sheet. The welded portion is obtained by subjecting the outer periphery of the bag portion of the film exterior body 4 to a thermocompression treatment, thereby welding the thermoplastic resin sheets of the two laminate films together. The sealing portion 14 seals each storage portion 12 and also connects the multiple storage portions 12 to one another.

[0071] The ends of the first electrode lead 8 and the second electrode lead 10 opposite to the end connected to the electrode body 2 protrude outside the film exterior housing 4. The first electrode lead 8 and the second electrode lead 10 connected to each electrode body 2 protrude on opposite sides of each other in the axial direction A. The first electrode leads 8 protrude on the same side. The sealing portion 14 of this embodiment has a pair of outer edge portions 26 that extend across the multiple housing portions 12, outside each housing portion 12 in the axial direction A. Each first electrode lead 8 protrudes outside the film exterior housing 4 from one outer edge portion 26. Each second electrode lead 10 protrudes outside the film exterior housing 4 from the other outer edge portion 26. The interface between each electrode lead and the outer edge portion 26 is sealed with a known sealant.

[0072] The film exterior body 4 is folded between adjacent storage sections 12 and snakes in the arrangement direction B. In other words, the film exterior body 4 extends in a roughly zigzag pattern when viewed from the axial direction A. By folding the film exterior body 4 in a zigzag pattern, the distance between each storage section 12 in the arrangement direction B can be made narrower than in the state before folding, and therefore the length of the energy storage device 1 in the arrangement direction B can be shortened.

[0073] Furthermore, in this embodiment, the multiple storage sections 12 are arranged so that their centers are aligned on the same straight line when viewed from the axial direction A while the film exterior body 4 is in a serpentine state. This makes it possible to prevent the size of the energy storage device 1 in the orthogonal direction C from increasing, compared to when the multiple storage sections 12 are arranged so that their centers are offset in the orthogonal direction C. Furthermore, the zigzag-folded sealing section 14 is located inside the storage sections 12 in the orthogonal direction C. This makes it possible to prevent the size of the energy storage device 1 in the orthogonal direction C from increasing when the film exterior body 4 is folded. Note that, in the present disclosure, the centers of the multiple storage sections 12 do not necessarily have to be aligned on the same straight line.

[0074] The sealing portion 14 has a first connecting portion 28 and a second connecting portion 30 that are sandwiched between two adjacent storage portions 12 and connect the two storage portions 12. The first connecting portions 28 and the second connecting portions 30 are arranged alternately in the arrangement direction B and are offset from each other in the orthogonal direction C. Each connecting portion is long in the axial direction A and extends parallel to the arrangement direction B. Each connecting portion is sandwiched between two storage portions 12 in the arrangement direction B and between two outer edge portions 26 in the axial direction A. Both ends of each storage portion 12 in the axial direction A are sealed by the outer edge portions 26, one end in the arrangement direction B is sealed by the first connecting portion 28, and the other end in the arrangement direction B is sealed by the second connecting portion 30.

[0075] As shown in FIG. 12 , before the outer edge portion 26 is folded, the region of the outer edge portion 26 that continues from the storage section 12, i.e., the region that overlaps with the storage section 12 as viewed from the axial direction A, extends linearly through the center of the storage section 12 as viewed from the axial direction A and obliquely with respect to the arrangement direction B. Furthermore, between two adjacent storage sections 12, the outer edge portion 26 on one storage section 12 and the outer edge portion 26 on the other storage section 12 extend in directions that are staggered. Furthermore, the outer edge portion 26 on the storage section 12 and the outer edge portion 26 on the first connecting portion 28 are connected to each other at a predetermined angle, i.e., non-linearly. The outer edge portion 26 on the storage section 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 exterior body 4, meander in the arrangement direction B.

[0076] The outer edge portion 26 is tilted from an upright state as shown in FIG. 12 in the orthogonal direction C to a lying state as shown in FIG. 11. This allows the dimensions of the energy storage device 1 in the axial direction A to be reduced. However, because the outer edge portion 26 is serpentine, simply tilting it in the orthogonal direction C will result in random bending. If the outer edge portion 26 is bent randomly, the number of fold lines formed and the total length will increase. Because the film exterior body 4 is made by welding two laminate films, the film is prone to peeling at the fold lines. For this reason, it is desirable to minimize the fold lines that occur when the outer edge portion 26 is tilted in the orthogonal direction C.

[0077] In contrast, in the energy storage device 1 of the present embodiment, the outer edge portion 26 is folded in a manner described below. Fig. 13 is a view of the energy storage device 1 as viewed from the axial direction A. Figs. 14(A) and 14(B) are perspective views of a portion of the energy storage device 1 as viewed from one side C1 in the orthogonal direction C. Figs. 15(A) and 15(B) are perspective views of a portion of the energy storage device 1 as viewed from the other side C2 in the orthogonal direction C.

[0078] As described above, the sealing portion 14 has the first connecting portion 28 and the second connecting portion 30. When viewed from the axial direction A, the first connecting portion 28 extends parallel to the center line L, offset to one side C1 in the orthogonal direction C from the center line L that passes through the centers of the multiple accommodating portions 12. On the other hand, the second connecting portion 30 extends parallel to the center line L, offset to the other side C2 in the orthogonal direction C from the center line L.

[0079] The outer edge portion 26 has a first tilting portion 32 and a second tilting portion 34. In FIG. 13 , the region indicated by the horizontal dashed line is the first tilting portion 32, and the region indicated by the vertical dashed line is the second tilting portion 34. The first tilting portion 32 is a region continuing from the first connecting portion 28 and the storage portion 12, and at the connection between the first connecting portion 28 and the storage portion 12, it bends from the connection to the second connecting portion 30 in the orthogonal direction C, i.e., the other side C2. On the other hand, the second tilting portion 34 is a region continuing from the second connecting portion 30 and the two first tilting portions 32 arranged on either side of the second connecting portion 30, and at the connection between the second connecting portion 30 and the two first tilting portions 32, it bends from the connection to the first connecting portion 28 in the orthogonal direction C, i.e., the one side C1. The connection between the first inclined portion 32 and the second inclined portion 34 corresponds to a fold line 36 where the outer edge portion 26, which has fallen toward the other side C2, is folded back toward the one side C1. One end point of the fold line 36 contacts the second connecting portion 30.

[0080] That is, the portion of the outer edge portion 26 above the first connecting portion 28 when viewed from the axial direction A leans toward the other side C2 and constitutes part of the first tilting portion 32. The portion above the second connecting portion 30 leans toward the one side C1 and constitutes part of the second tilting portion 34. The portion above the storage portion 12 is leaned toward the other side C2 and then folded back diagonally and leaned toward the one side C1, with the portion leaning toward the other side C2 constituting part of the first tilting portion 32 and the portion leaning toward the one side C1 constituting part of the second tilting portion 34.

[0081] Therefore, the first inclined portion 32 and the second inclined portion 34 overlap each other on the storage portion 12 when viewed from the axial direction A, forming an overlapping portion 38. In FIG. 13 , the area indicated by solid diagonal lines is the overlapping portion 38. In the overlapping portion 38, the first inclined portion 32 is positioned closer to the storage portion 12 than the second inclined portion 34. In other words, the second inclined portion 34 overlaps the first inclined portion 32. The first inclined portion 32 also has a valley fold 40 that fits between adjacent storage portions 12. The portion of the first connecting portion 28 that is loosened in the arrangement direction B by leaning toward the other side C2, i.e., the excess portion of the first inclined portion 32 due to the difference in circumferential length between the inner peripheral edge side and the outer peripheral edge side, fits between the two storage portions 12, forming the valley fold 40.

[0082] By folding outer edge portion 26 in the manner described above, it is possible to reduce the number of fold lines formed when outer edge portion 26 is folded and the total length of the fold lines. Furthermore, in this embodiment, second inclined portion 34 has an isosceles trapezoidal shape when viewed from axial direction A, with the connection portion with second connecting portion 30 (the boundary between second inclined portion 34 and second connecting portion 30) as the base and two fold lines 36 connecting first inclined portion 32 and second inclined portion 34 (the connection portions between first inclined portion 32 and second inclined portion 34) as legs. This makes it possible to further shorten the total length of the fold lines formed in outer edge portion 26.

[0083] When the outer edge portion 26 is folded as described above, the following conditions are met. That is, as shown in FIG. 13 , the end point of the fold line 36 on the side opposite the second connecting portion 30 is defined as end point P1, and the end point that meets the second connecting portion 30 is defined as end point P2. The connection between the first tilting portion 32 and the storage portion 12 is defined as boundary line L1, and the perpendicular line drawn from end point P1 to boundary line L1 is defined as perpendicular line L2. The intersection of boundary line L1 and perpendicular line L2 is defined as intersection point P3. The outermost edge of the film exterior body 4 is defined as outermost edge L3. The fold line 36 and outermost edge L3 meet at end point P1. On both sides of each second connecting portion 30 in the arrangement direction B, a triangle is formed with end point P1, end point P2, and intersection point P3 as vertices. In this case, the sum of the length from the intersection point P3 to the end point P2 in one triangle, the length of the second connecting portion 30 (the length between the two end points P2), and the length from the end point P2 to the intersection point P3 in the other triangle is approximately equal to the length of the outermost side L3 between the two end points P1.

[0084] The first electrode leads 8 of each electrode body 2 are electrically connected by a bus bar 42. The bus bar 42 is a strip-shaped conductive member extending in the arrangement direction B. Specifically, as shown in FIG. 14(B), the bus bar 42 is inserted from one side C1 between each housing portion 12 and each first electrode lead 8. 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. This electrically connects the multiple electrode bodies 2. An insulating sheet may be interposed between the bus bar 42 and each housing portion 12. The same applies to the electrical connection of the second electrode leads 10 of each electrode body 2.

[0085] In this embodiment, the multiple first electrode leads 8 protrude to the same side. Therefore, when each electrode lead is joined to the bus bar 42, all of the electrode bodies 2 are connected in parallel to one another. However, the manner of electrical connection of each electrode body 2 is not particularly limited. For example, the first electrode leads 8 and the second electrode leads 10 may be arranged alternately, and adjacent first electrode leads 8 and second electrode leads 10 may be electrically connected. In other words, the multiple electrode bodies 2 may be connected in series. Furthermore, the first electrode lead 8 and the second electrode lead 10 of each electrode body 2 may protrude to the same side in the axial direction A. This allows the electrode bodies 2 to be electrically connected simply by arranging the bus bar 42 on only one side in the axial direction A. This reduces the number of steps required for connecting the energy storage device 1.

[0086] 16 is a diagram showing an arrangement of a plurality of energy storage devices 1. When a plurality of energy storage devices 1 are combined to form an energy storage module, the plurality of energy storage devices 1 are arranged, for example, in the orthogonal direction C. The orientation of each energy storage device 1 is determined so that the housing sections 12 are aligned in the same direction. The first electrode leads 8 of each energy storage device 1 are arranged so as to extend to the same side in the orthogonal direction C. The same applies to the second electrode leads 10.

[0087] Two energy storage devices 1 adjacent to each other 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 energy storage device 1 is located between the axes of two adjacent electrode bodies 2 of the other energy storage device 1. In other words, the accommodation section 12 of one energy storage device 1 fits into the valley between the two accommodation sections 12 of the other energy storage device 1. This makes it possible to reduce the dimensions of the energy storage module in the orthogonal direction C. Note that although two energy storage devices 1 are illustrated in FIG. 16 , the number of energy storage devices 1 constituting the energy storage module may be three or more. Furthermore, although the two energy storage devices 1 shown in FIG. 16 are oriented so that the first electrode leads 8 protrude on the same side, they may also be arranged so that the first electrode leads 8 protrude in opposite directions.

[0088] 17 is a schematic diagram illustrating the arrangement of the electrode leads. The following describes the arrangement of the electrode leads using the first electrode lead 8 as an example, 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 inclined portion 32 and the housing portion 12. Furthermore, when the first electrode lead 8 passes through the overlapping portion 38, it is also bent at the fold line 36. When the first electrode lead 8 is bent, the first electrode lead 8 and the outer edge portion 26 may peel off from the bent portion, resulting in the formation of a peeled portion 44.

[0089] Peeling portion 44 is more likely to occur in locations where a larger number of laminated components are present. The portion where first electrode lead 8 and outer edge portion 26 overlap has a structure in which at least three components, specifically, first electrode lead 8 and two laminate films, are laminated. Therefore, peeling portion 44 is more likely to form there than in portions where first electrode lead 8 does not extend. Because first electrode lead 8 is bent at two locations as described above, two peeling portions 44 may be formed along the protruding direction of first electrode lead 8. If storage portion 12 is connected to the outside of film exterior body 4 through two peeling portions 44, a leakage path for the contents of storage portion 12 is formed, and the sealing performance of sealing portion 14 is impaired at that location.

[0090] In contrast, as shown in Fig. 17, the first electrode lead 8 in this embodiment is arranged to pass through a position offset from the midpoint 36a of the fold line 36 (connection portion) connecting the first inclined portion 32 and the second inclined portion 34. At the midpoint 36a of the fold line 36, a distance D1 from the boundary line L1 to the fold line 36 and a distance D2 from the fold line 36 to the outermost edge L3 of the film exterior body 4 are approximately equal. Therefore, when the first electrode lead 8 passes through the midpoint 36a, two peeled portions 44 that may be formed along the first electrode lead 8 increase the likelihood that the above-mentioned leakage path will be formed. Therefore, by arranging the first electrode lead 8 so as to be offset from the midpoint 36a of the fold line 36, it is possible to prevent a deterioration in the sealing performance of the electrode body 2 due to folding of the outer edge portion 26.

[0091] The fold line 36 moves away from the outermost edge L3 the closer it is to the second connecting portion 30 than the midpoint 36a. Therefore, by positioning the position where the first electrode lead 8 passes through the fold line 36 closer to the second connecting portion 30 than the midpoint 36a, the peeled portion 44 that may form around the fold line 36 can be spaced away from the outermost edge L3. This makes it possible to suppress the formation of a leakage path. On the other hand, the fold line 36 moves away from the boundary line L1 the farther it is from the second connecting portion 30 than the midpoint 36a. Therefore, by positioning the position where the first electrode lead 8 passes through the fold line 36 farther from the second connecting portion 30 than the midpoint 36a, it is possible to separate the peeled portion 44 that may form around the fold line 36 from the peeled portion 44 that may form around the boundary line L1. This makes it possible to suppress the formation of a leakage path.

[0092] Preferably, the first electrode lead 8 is arranged so that at least a portion thereof passes through the outer end region R (the outer 1 / 4 region) when the folding line 36 is divided into four equal parts. More preferably, the first electrode lead 8 is arranged so that the entire first electrode lead 8 passes through the outer end region R. This allows the peeled portion 44, which may be formed around the folding line 36, to be further separated from the outermost edge L3 or from the peeled portion 44 formed around the boundary line L1. This further reduces the formation of leakage paths. Alternatively, the first electrode lead 8 may be arranged so that it passes outside the overlapping portion 38. In this case, the first electrode lead 8 is bent only at the point where it overlaps with the boundary line L1. This further reduces the formation of leakage paths. Note that the peeled portion 44 is not necessarily formed in the energy storage device 1 of the present disclosure (it may not be formed in some cases).

[0093] An example of a method for manufacturing the energy storage device 1 is shown below. FIGS. 18(A) to 18(C) and 19(A) to 19(C) are process diagrams of the method for manufacturing the energy storage device 1. First, as shown in FIG. 18(A), a first laminate film 20a is prepared. A plurality of semi-cylindrical depressions 18 are formed in advance in the first laminate film 20a. The depressions 18 are formed, for example, by subjecting the first laminate film 20a to a known process such as press working. An electrode body 2 is placed in each depression 18. A first electrode lead 8 and a second electrode lead 10 are connected to the electrode body 2 in advance. A sealant (not shown) is provided in the first electrode lead 8 and the second electrode lead 10.

[0094] 18(B), the second laminate film 20b is then superimposed on the first laminate film 20a to form the film exterior housing 4. The second laminate film 20b has semi-cylindrical depressions 18 formed in positions facing the depressions 18 in the first laminate film 20a. Therefore, when the first laminate film 20a and the second laminate film 20b are superimposed, a bag portion, in other words, a storage portion 12, is formed by the pair of depressions 18. The method for forming the depressions 18 in the second laminate film 20b is the same as the method for forming the depressions 18 in the first laminate film 20a. With the electrode body 2 housed in the storage portion 12, the tip of the first electrode lead 8 and the tip of the second electrode lead 10 protrude outside the film exterior housing 4.

[0095] Next, as shown in FIG. 18(C), a thermocompression process is performed on a portion of the film exterior body 4 to form a welded portion 22. The portion of the film exterior body 4 that is not subjected to the thermocompression process becomes a non-welded portion 24. The non-welded portion 24 is arranged so as to connect each housing section 12 to the outside of the film exterior body 4. In the present embodiment, the non-welded portion 24 is provided so as to connect one of the four sides of each housing section 12 from which the first electrode lead 8 protrudes to the outside of the film exterior body 4. The remaining three sides of each housing section 12 are surrounded by the welded portion 22. The interface between the film exterior body 4 and the second electrode lead 10 is sealed with a sealant.

[0096] Next, as shown in FIG. 19(A), electrolyte 16 is injected into each housing portion 12 through the non-welded portion 24. After the electrolyte 16 is injected, thermocompression bonding is also performed on the non-welded portion 24 as shown in FIG. 19(B). As a result, a sealing portion 14 is formed that surrounds the entire periphery of each housing portion 12. The interface between the film exterior body 4 and the first electrode lead 8 is sealed with a sealant. Next, as shown in FIG. 19(C), the film exterior body 4 is folded in a zigzag shape. The outer edge portion 26 is also folded. Through these steps, the energy storage device 1 is obtained. The folding of the outer edge portion 26 can be achieved, for example, by applying a jig corresponding to the shape of the first tilt portion 32 from the other side C2 and a jig corresponding to the shape of the second tilt portion 34 from the one side C1, and pressing the outer edge portion 26 with a press.

[0097] The manufacturing method of the energy storage device 1 is not limited to the above. For example, each electrode body 2 may be wrapped in a single laminate film having a length twice that of the energy storage device 1, which may be folded in half. Furthermore, when the required amount of electrolyte solution 16 is small, the step of injecting the electrolyte solution 16 shown in FIG. 19(A) can be omitted by pre-impregnating the inter-electrode separator with the electrolyte solution 16. In this case, in the thermocompression bonding step shown in FIG. 18(C), the entire periphery of each housing portion 12 is subjected to thermocompression bonding to form the sealing portion 14.

[0098] As described above, the energy storage device 1 according to this embodiment includes a plurality of cylindrical electrode bodies 2, a plurality of housing sections 12 that individually encase the plurality of electrode bodies 2, and a film exterior body 4 that has a sealing section 14 that seals each housing section 12 and connects the plurality of housing sections 12 to one another, and that folds between adjacent housing sections 12 and meanders in the arrangement direction B. The sealing section 14 has a first connecting section 28 and a second connecting section 30 that are sandwiched between two adjacent housing sections 12 and connect the two housing sections 12, and an outer edge section 26 that extends across the plurality of housing sections 12, outside each housing section 12 in the axial direction A of the electrode body 2.

[0099] The first connecting portions 28 and the second connecting portions 30 are arranged alternately in the arrangement direction B of the electrode body 2 and extend in the arrangement direction B while being offset from each other in the orthogonal direction C that is perpendicular to the axial direction A and the arrangement direction B. The outer edge portion 26 has a first inclined portion 32 and a second inclined portion 34. The first inclined portion 32 is continuous with the first connecting portion 28 and the housing portion 12 and bends in the orthogonal direction C toward the second connecting portion 30 from the connection point therebetween, and has a valley fold 40 that fits between adjacent housing portions 12. The second inclined portion 34 is continuous with the second connecting portion 30 and the two first inclined portions 32 that are arranged on either side of the second connecting portion 30 and bends in the orthogonal direction C toward the first connecting portion 28 from the connection point therebetween. The first inclined portion 32 and the second inclined portion 34 overlap each other on the accommodating portion 12 when viewed from the axial direction A to form an overlapping portion 38.

[0100] When the electrode bodies 2 are individually housed in multiple housing sections 12, a large load may be placed on the sealing section 14 due to gas generation in the housing sections 12 and swelling of the electrode bodies 2 as the energy storage device 1 is charged and discharged. If the sealing section 14 is damaged and connects the inside of the housing section 12 with the outside of the film exterior body 4, there is a risk of the electrolyte solution 16 leaking out of the film exterior body 4. Furthermore, if the sealing section 14 is damaged and connects adjacent housing sections 12, the adjacent electrode bodies 2 may be short-circuited or the amount of electrolyte solution 16 may be uneven in the two housing sections 12, which may reduce the power generation performance of the energy storage device 1.

[0101] For this reason, it is desirable to increase the area of ​​the sealing portion 14 and increase the strength of the sealing portion 14 in order to ensure the sealing performance of the electrode body 2. However, increasing the size of the sealing portion 14 leads to an increase in the size of the energy storage device 1. Furthermore, an increase in the size of the energy storage device 1 leads to a decrease in the packing rate of the electrode body 2 in the energy storage module, that is, a decrease in the energy density of the energy storage module 100. On the other hand, if the sealing portion 14 is made smaller in order to increase the energy density of the energy storage module, the sealing performance of the electrode body 2 is sacrificed.

[0102] In contrast, in the energy storage device 1 of the present embodiment, the film exterior body 4 is folded in a serpentine manner in the arrangement direction B. This makes it possible to shorten the interval between adjacent storage sections 12, and therefore the length of the energy storage device 1 in the arrangement direction B, without making the sealed sections 14 smaller. Furthermore, in the energy storage device 1 of the present embodiment, outer edge sections 26 of the sealed sections 14 that extend outside the storage sections 12 in the axial direction A are inclined in the orthogonal direction C. This makes it possible to shorten the length of the energy storage device 1 in the axial direction A.

[0103] Furthermore, when the outer edge portion 26, which meanders in the arrangement direction B, is folded, first inclined portions 32 and second inclined portions 34, which are inclined to opposite sides in the orthogonal direction C, are alternately formed in the arrangement direction B, and a portion of each inclined portion overlaps. Furthermore, a valley fold 40 is provided in the first inclined portion 32. This minimizes fold lines, wrinkles, distortion, and the like that occur when the outer edge portion 26 is folded, thereby preventing a decrease in the sealing performance of the electrode assembly 2. Therefore, according to the energy storage device 1 of this embodiment, the energy storage device 1 can be miniaturized while preventing a decrease in the sealing performance of the electrode assembly 2, and the mounting efficiency of the energy storage device 1, i.e., the energy density of the energy storage module, can be improved.

[0104] Furthermore, the energy storage device 1 of the present embodiment has a pouch structure in which multiple electrode bodies 2 are sealed in a film exterior body 4, and therefore the weight of the energy storage module can be reduced compared to when each electrode body 2 is individually sealed in an exterior can. In particular, when the number of electrode bodies 2 mounted on the energy storage module increases as the capacity of the energy storage module increases, a significant weight reduction effect can be achieved.

[0105] Furthermore, when viewed from the axial direction A, the second inclined portion 34 of this embodiment has an isosceles trapezoidal shape with the connection portion with the second connecting portion 30 as the base and two fold lines 36, which are connection portions connecting the first inclined portion 32 and the second inclined portion 34, as legs. This makes it possible to further shorten the total length of the fold lines that are generated when the outer edge portion 26 is folded. Therefore, it is possible to further suppress a deterioration in the sealing performance of the electrode body 2.

[0106] The energy storage device 1 of this embodiment also includes strip-shaped first electrode leads 8 and second electrode leads 10 that are electrically connected to each electrode body 2 and protrude from the outer edge portion 26. Each electrode lead is arranged to pass through a position shifted from the midpoint 36a of the fold line 36, which is the connection portion that connects the first inclined portion 32 and the second inclined portion 34. Furthermore, each electrode lead is arranged so that at least a portion of the fold line 36 passes through the outer end region R when the fold line 36 is divided into four equal parts, or passes outside the overlapping portion 38. This makes it possible to further suppress deterioration in the sealing performance of the electrode body 2 due to folding of the outer edge portion 26.

[0107] The embodiments of the present disclosure have been described in detail above. The above-described embodiments merely illustrate specific examples of implementing the present disclosure. The content of the embodiments does not limit the technical scope of the present disclosure, and many design modifications, such as changing, adding, or deleting components, are possible within the scope of the invention defined in the claims. A new embodiment with design modifications will combine the effects of the combined embodiments and modifications. In the above-described embodiments, content that allows such design modifications is emphasized by using notations such as "in this embodiment" or "in this embodiment," but design modifications are also permitted even in content without such notation. Furthermore, any combination of components included in each embodiment is also valid as an aspect of the present disclosure. Hatching on cross sections in the drawings does not limit the material of the hatched object. [Industrial Applicability]

[0108] The present disclosure can be used in power storage devices and power storage modules. [Explanation of symbols]

[0109] 1 Energy storage device, 2 Electrode body, 4 Film exterior body, 12 Storage section, 14 Sealing section, 14a First edge section, 26 Outer edge section, 28 First connecting section, 30 Second connecting section, 32 First tilting section, 34 Second tilting section, 36 Folding line, 36a Midpoint, 38 Overlapping section, 40 Valley fold section, 100 Energy storage module, 104 Holder, 112 Side panel.

Claims

1. A plurality of cylindrical electrode bodies; a film exterior body having a plurality of housing sections that individually encase the plurality of electrode assemblies, and a sealing section that seals each housing section and connects the plurality of housing sections to one another, the film exterior body being folded between adjacent housing sections and meandering in the arrangement direction of the electrode assemblies, The sealing portion is a first connecting portion and a second connecting portion sandwiched between two adjacent storage portions to connect the two storage portions; an outer edge portion extending across the plurality of housing portions on the outer side of each housing portion in the axial direction of the electrode body; the first connecting portions and the second connecting portions are arranged alternately in the arrangement direction, and extend in the arrangement direction while being shifted from each other in the axial direction and an orthogonal direction orthogonal to the arrangement direction; The outer edge portion is a first inclined portion that is continuous with the first connecting portion and the storage portion, bends toward the second connecting portion in the orthogonal direction from a connection portion between the first connecting portion and the storage portion as a starting point, and has a valley fold that fits between adjacent storage portions; a second inclined portion that is continuous with the second connecting portion and the two first inclined portions that are arranged on either side of the second connecting portion, and that bends toward the first connecting portion in the orthogonal direction from a connection portion between the second connecting portion and the two first inclined portions as a starting point, the first inclined portion and the second inclined portion overlap each other on the accommodation portion when viewed from the axial direction to form an overlapping portion, The sealing portion is located inside the periphery of the accommodation portion in the orthogonal direction. Energy storage device.

2. When viewed from the axial direction, the second tilting portion has an isosceles trapezoidal shape with a connection portion with the second connecting portion as a base and two fold lines that are the connection portions between the first tilting portion and the second tilting portion as legs. The power storage device according to claim 1 .

3. a strip-shaped electrode lead electrically connected to each electrode body and protruding from the outer edge; the electrode lead is disposed so as to pass through a position shifted from a midpoint of a folding line which is the connection portion between the first inclined portion and the second inclined portion; The electricity storage device according to claim 1 or 2.

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

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