JP6942092B2 - Battery module - Google Patents

Description

One aspect of the present invention relates to a battery module.

As a conventional battery module, for example, a thin battery as described in Patent Document 1 is known. The thin battery described in Patent Document 1 is arranged so as to surround a positive electrode on one main surface of a bipolar electrode having a positive electrode, a negative electrode and a current collector, an electrolyte layer containing a separator and an electrolytic solution, and one main surface of the current collector. It includes a first seal portion, a second seal portion arranged on the other main surface of the current collector so as to surround the negative electrode, and a tube penetrating the second seal portion. One end of the tube faces the internal space defined by the separator, the current collector and the second seal, and the other end of the tube faces the outer space of the second seal. The gas generated inside the battery is discharged to the outside of the battery via a tube.

Japanese Unexamined Patent Publication No. 2010-287451

In the above-mentioned prior art, the tube functions as a pressure regulating valve that discharges gas in the internal space when the pressure in the internal space rises. In a battery module provided with such a pressure regulating valve, when the pressure in the internal space rises and the pressure regulating valve opens, the electrolytic solution may be released together with the gas in the internal space. In this case, the amount of electrolytic solution remaining in the internal space is reduced.

One aspect of the present invention is to provide a battery module in which the electrolytic solution in the internal space is not easily discharged from the pressure regulating valve even when the pressure regulating valve is opened.

In the battery module according to one aspect of the present invention, a bipolar electrode having a positive electrode formed on the first surface of the current collector plate and a negative electrode formed on the second surface of the current collector plate is laminated in the first direction. An electrode laminate, a seal portion arranged so as to surround the electrode laminate and having a communication hole communicated with an internal space provided between adjacent bipolar electrodes, and a pressure adjusting valve that closes the communication hole. An electrolytic solution is housed in the internal space, and the communication hole is arranged between the pressure adjusting valve and the internal space in a second direction orthogonal to the first direction. The negative electrode has a main surface that intersects the first direction, and the main surface has a first edge portion farthest from the communication hole and a second edge closest to the communication hole in the second direction. The internal space has a portion, and the internal space is orthogonal to the second direction and is located on the opposite side of the communication hole with respect to the first plane including the first edge portion, and the said portion. It has a second portion orthogonal to the second direction and located on the same side as the communication hole with respect to the second plane including the second edge portion, and the volume of the first portion is the second portion. Is larger than the volume of.

According to this battery module, when gas is generated from the positive electrode or the negative electrode and the pressure in the internal space rises, the gas flows from the second portion having a small volume to the first portion having a large volume. Along with this gas flow, the electrolytic solution in the internal space moves away from the communication hole in the second direction. Therefore, even if the pressure in the internal space rises and the pressure regulating valve opens, the electrolytic solution in the internal space is unlikely to be discharged from the pressure regulating valve.

The volume of the first portion may be 5 times or more the volume of the second portion. In this case, since the amount of the electrolytic solution contained in the first portion can be increased, the amount of the electrolytic solution contained in the second portion can be further reduced.

The main surface has a rectangular shape, and the main surface may have a first side in the first plane and a second side in the second plane.

The electrode laminate is provided with a plurality of the internal spaces, and each of the plurality of internal spaces may have the first portion and the second portion. In this case, the electrolytic solution in each internal space is unlikely to be discharged from the pressure regulating valve.

At least one of the positive electrode and the negative electrode may have a groove extending in the second direction. In this case, the electrolytic solution in the internal space can move away from the communication hole through the groove.

The power storage device according to one aspect of the present invention is a power storage device including a plurality of stacked battery modules and a restraint unit for restraining the plurality of battery modules in the stacking direction of the plurality of battery modules. Each of the plurality of battery modules is the above-mentioned battery module, and the first portions of the plurality of battery modules are at least partially overlapped with each other when viewed from the stacking direction. The second portion of the plurality of battery modules is at least partially overlapped with each other.

When the first portion and the second portion overlap each other when viewed from the stacking direction, the load applied to the second portion is relatively smaller than that of the first portion. On the other hand, when the plurality of first portions are at least partially overlapped with each other when viewed from the stacking direction, the load applied to the first portions can be easily made uniform. Further, when the plurality of second portions are at least partially overlapped with each other when viewed from the stacking direction, it is easy to make the load applied to the second portions uniform.

According to one aspect of the present invention, it is possible to provide a battery module in which the electrolytic solution in the internal space is not easily discharged from the pressure regulating valve even when the pressure regulating valve is opened.

It is a schematic cross-sectional view which shows the power storage device provided with the battery module which concerns on one Embodiment of this invention. It is a schematic cross-sectional view of a battery module. It is a schematic perspective view of a battery module. It is a figure which shows a part of the battery module schematically. It is a figure which shows typically the gas flow when the pressure of an internal space rises. It is a top view which shows a part of the battery module which concerns on a modification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate description is omitted. The drawings show the XYZ Cartesian coordinate system as needed.

FIG. 1 is a schematic cross-sectional view showing a power storage device including a battery module according to an embodiment of the present invention. In FIG. 1, the power storage device 1 is used as a battery for a vehicle such as a forklift, a hybrid vehicle, or an electric vehicle. The power storage device 1 includes a bipolar battery 2 as a plurality of (three in this case) battery modules. The bipolar battery 2 is, for example, a nickel hydrogen secondary battery.

The plurality of bipolar batteries 2 are laminated via a metal conductive plate 3. The conductive plates 3 are also arranged on the outside of the bipolar batteries 2 located at both ends in the stacking direction (Z-axis direction). The Z-axis direction is, for example, the vertical direction. The bipolar battery 2 and the conductive plate 3 have, for example, a rectangular shape (rectangular shape in a plan view) when viewed from the stacking direction. The conductive plate 3 is electrically connected to the adjacent bipolar battery 2. As a result, the plurality of bipolar batteries 2 are connected in series in the stacking direction.

The positive electrode terminal 4 is connected to the conductive plate 3 located at one end (lower end in this case) in the stacking direction. The negative electrode terminal 5 is connected to the conductive plate 3 located at the other end (here, the upper end) in the stacking direction. The positive electrode terminal 4 and the negative electrode terminal 5 extend in a direction perpendicular to the stacking direction (X-axis direction). The X-axis direction is, for example, the horizontal direction. By providing such a positive electrode terminal 4 and a negative electrode terminal 5, charging / discharging of the power storage device 1 can be performed.

The conductive plate 3 can also function as a heat radiating plate for releasing the heat generated in the bipolar battery 2. The conductive plate 3 is provided with a plurality of voids 3a extending in a direction (Y-axis direction) perpendicular to the stacking direction and the extending direction of the positive electrode terminal 4 and the negative electrode terminal 5. The Y-axis direction is, for example, the horizontal direction. By passing a refrigerant such as air through these voids 3a, the heat from the bipolar battery 2 can be efficiently released to the outside.

Further, the power storage device 1 includes a restraint unit 6 that restrains the bipolar battery 2 and the conductive plate 3 in the stacking direction. The restraint unit 6 has a pair of restraint plates 7 that sandwich the bipolar battery 2 and the conductive plate 3 in the stacking direction, and a plurality of sets of bolts 8 and nuts 9 that fasten the restraint plates 7 to each other.

The restraint plate 7 is made of a metal such as iron. An insulating film 10 such as a resin film is arranged between each restraint plate 7 and the conductive plate 3. The restraint plate 7 and the insulating film 10 have, for example, a rectangular shape in a plan view. With the shaft portion 8a of the bolt 8 inserted through the insertion holes 7a provided in each restraint plate 7, the nut 9 is screwed into the tip portion of the shaft portion 8a, whereby the bipolar battery 2, the conductive plate 3, and the insulating film are formed. A restraining load in the stacking direction is applied to 10.

FIG. 2 is a schematic cross-sectional view of the bipolar battery 2. FIG. 3 is a schematic perspective view of the bipolar battery 2. In FIGS. 2 and 3, the bipolar battery 2 has a structure (plural cell structure) in which a plurality of cells (for example, 24 cells) are laminated. The bipolar battery 2 is provided as an electrode laminate 15 in which a plurality of bipolar electrodes 13 are laminated in the Z-axis direction (first direction) via a separator 14 and a sealing portion arranged so as to surround the electrode laminate 15. A frame body 16 and a plurality of (here, four) pressure adjusting valves 12 attached to the frame body 16 are provided.

The bipolar electrode 13 and the separator 14 have, for example, a rectangular shape in a plan view. The separator 14 is arranged between the bipolar electrodes 13 adjacent to each other in the stacking direction. The bipolar electrode 13 includes a nickel foil 17 which is an example of a current collecting plate (conductive plate or metal plate), a positive electrode 18 formed on the upper surface 17a (first surface) of the nickel foil 17, and a lower surface 17b of the nickel foil 17. It has a negative electrode 19 formed on (a second surface opposite to the first surface). The positive electrode 18 is a positive electrode layer having a thickness in the Z-axis direction. The negative electrode 19 is a negative electrode layer having a thickness in the Z-axis direction. The positive electrode 18 and the negative electrode 19 have, for example, a rectangular shape in a plan view.

The positive electrode 18 of the bipolar electrode 13 faces the negative electrode 19 of one of the bipolar electrodes 13 adjacent to each other in the stacking direction with the separator 14 interposed therebetween. The negative electrode 19 of the bipolar electrode 13 faces the positive electrode 18 of the other bipolar electrode 13 adjacent to each other in the stacking direction with the separator 14 interposed therebetween.

A positive electrode side terminal electrode 20 is arranged on the lowermost layer of the electrode laminate 15. The positive electrode side terminal electrode 20 has a nickel foil 17 and a positive electrode 18 formed on the upper surface 17a of the nickel foil 17. A negative electrode side terminal electrode 21 is arranged on the uppermost layer of the electrode laminate 15. The negative electrode side terminal electrode 21 has a nickel foil 17 and a negative electrode 19 formed on the lower surface 17b of the nickel foil 17. The positive electrode 18 of the positive electrode side terminal electrode 20 faces the negative electrode 19 of the lowermost bipolar electrode 13 with the separator 14 interposed therebetween. The negative electrode 19 of the negative electrode side terminal electrode 21 faces the positive electrode 18 of the uppermost bipolar electrode 13 with the separator 14 interposed therebetween. The nickel foil 17 of the positive electrode side terminal electrode 20 and the negative electrode side terminal electrode 21 is connected to the conductive plates 3 (see FIG. 1) adjacent to each other in the stacking direction.

The positive electrode 18 is formed by applying a positive electrode active material to one surface of the nickel foil 17. As the positive electrode active material, for example, nickel hydroxide coated with a cobalt (Co) oxide is used. The negative electrode 19 is formed by applying a negative electrode active material to the other surface of the nickel foil 17. As the negative electrode active material, for example, a hydrogen storage alloy is used. The edge portion 17c of the nickel foil 17 is an uncoated region in which the positive electrode active material and the negative electrode active material are not coated.

The separator 14 is arranged between the positive electrode 18 and the negative electrode 19, and separates the positive electrode 18 and the negative electrode 19. The separator 14 is smaller than the nickel foil 17 and larger than the positive electrode 18 and the negative electrode 19 when viewed from the stacking direction. The separator 14 is formed in a sheet shape, for example. The separator 14 is formed of a porous film made of a polyolefin resin such as polyethylene (PE) or polypropylene (PP), or a non-woven fabric or woven fabric made of PE, PP, polyethylene terephthalate (PET), methyl cellulose or the like. Further, the separator 14 may be reinforced with a vinylidene fluoride resin compound or the like. The shape of the separator 14 is not particularly limited to a sheet shape, but may be a bag shape.

The frame body 16 is arranged around the electrode laminate 15, a plurality of primary seal portions 22 for holding the edge portions 17c of each nickel foil 17, and secondary seals arranged around these primary seal portions 22. It has a unit 23.

Each primary seal portion 22 is arranged for each nickel foil 17 along the stacking direction. The primary seal portion 22 is formed in a frame shape. The primary seal portion 22 is joined to the edge portion 17c of the nickel foil 17 by heat welding.

An internal space V defined by the nickel foil 17, the positive electrode 18, the negative electrode 19, and the primary sealing portion 22 is provided between the nickel foils 17 adjacent to each other in the stacking direction. Therefore, the electrode laminate 15 is provided with a plurality of internal spaces V. For example, an alkaline electrolytic solution is housed in the internal space V including the void portion in the separator 14. As the alkaline electrolytic solution, an alkaline solution containing, for example, an aqueous potassium hydroxide solution is used. The primary seal portion 22 seals the internal space V. Each cell of the bipolar battery 2 is composed of two nickel foils 17, a positive electrode 18, a negative electrode 19, a separator 14, and a primary seal portion 22, and has an internal space V.

The secondary seal portion 23 has a square tubular shape. The secondary seal portion 23 further seals the internal space V. The secondary seal portion 23 is joined to each primary seal portion 22. The secondary seal portion 23 is formed by, for example, injection molding or the like.

The primary seal portion 22 and the secondary seal portion 23 are made of a resin such as polypropylene (PP), polyphenylene sulfide (PPS), or modified polyphenylene ether (modified PPE).

As shown in FIG. 2, the frame body 16 has a communication hole 16a that communicates with each internal space V. The communication hole 16a penetrates from the inner peripheral surface 16b of the frame body 16 facing the internal space V to the outer peripheral surface 16c of the frame body 16 in the X-axis direction (second direction) orthogonal to the Z-axis direction. The communication hole 16a is closed by a pressure adjusting valve 12 attached to the outer peripheral surface 16c. For example, one pressure regulating valve 12 closes a plurality of (six in this case) communication holes 16a. The positions of the communication holes 16a in the Y-axis direction are different from each other. When the pressure in the internal space V rises, the pressure regulating valve 12 opens, and the gas in the internal space V is discharged to the outside of the bipolar battery 2 through the communication hole 16a. The communication hole 16a is arranged between the pressure adjusting valve 12 and the internal space V in the X-axis direction.

FIG. 4 is a diagram schematically showing a part of the bipolar battery 2. FIG. 4A is an enlarged cross-sectional view of a part of FIG. FIG. 4B is a plan view of a part of the bipolar battery 2 when the negative electrode 19 is viewed from the Z-axis direction. As shown in FIG. 4, the negative electrode 19 has a main surface 19a that intersects in the Z-axis direction. The main surface 19a is, for example, a plane orthogonal to the Z-axis direction. In the present embodiment, the main surface 19a has a rectangular shape. The main surface 19a has a first edge portion 19e1 farthest from the communication hole 16a and a second edge portion 19e2 closest to the communication hole 16a in the X-axis direction. The first edge portion 19e1 is the first side of the rectangle. The second edge portion 19e2 is the second side opposite to the first side. The first side and the second side extend in the Y-axis direction. When the main surface 19a is rectangular, the first edge portion 19e1 and the second edge portion 19e2 may have short sides. In this case, the first edge portion 19e1 can be kept away from the communication hole 16a in the X-axis direction. The inner peripheral surface 16b of the frame body 16 has a rectangular shape when viewed from the Z-axis direction. When viewed from the Z-axis direction, the inner peripheral surface 16b is arranged so as to surround the main surface 19a.

Each internal space V has a first portion R1 located on the opposite side of the communication hole 16a with respect to the first plane P1 including the first edge portion 19e1 and a second plane P2 including the second edge portion 19e2. It has a second portion R2 located on the same side as the communication hole 16a, and a third portion R3 arranged between the first portion R1 and the second portion R2. Both the first plane P1 and the second plane P2 are orthogonal to each other in the X-axis direction. The first portion R1, the second portion R2, and the third portion R3 are void portions capable of accommodating the electrolytic solution.

The volume V1 of the first portion R1 is larger than the volume V2 of the second portion R2 (V1> V2). The volume V1 may be 5 times or more of the volume V2, or may be 10 times or less. The volume V1 is, for example, 0.5 to 1.5 cc. The volume V2 is, for example, 0.1 to 0.3 cc.

For example, the volume of the rectangular parallelepiped region surrounded by the upper surfaces 17a and 17b of the adjacent nickel foils 17 facing each other, the inner peripheral surface 16b of the frame body 16, and the first plane P1 is V1a, and the first of the separators 14 Assuming that the volume of the non-void region (the region where the constituent material of the separator 14 exists) of the portion located on the opposite side of the communication hole 16a with respect to the plane P1 is V1b, the volume V1 is represented by the following equation (1). ..
V1 = V1a-V1b ... (1)

Assuming that the area of the lower surface 17b of the nickel foil 17 surrounded by the inner peripheral surface 16b of the frame body 16 and the first plane P1 is S1 and the distance between the adjacent nickel foils 17 is H, the volume V1a is as follows. It is represented by (2).
V1a = S1 × H ... (2)

Assuming that the volume of the rectangular parallelepiped region surrounded by the outer surface of the portion of the separator 14 opposite to the communication hole 16a with respect to the first plane P1 and the first plane P1 is V1s, and the porosity of the separator 14 is ε. , Volume V1b is represented by the following formula (3).
V1b = V1s × (1-ε)… (3)

The volume V2 can be calculated in the same manner. For example, it is surrounded by an upper surface 17a and a lower surface 17b of adjacent nickel foils 17 facing each other, an inner peripheral surface 16b of the frame body 16 (including an opening end on the internal space V side of the communication hole 16a), and a second plane P2. Assuming that the volume of the rectangular parallelepiped region is V2a and the volume of the non-void region of the separator 14 located on the same side as the communication hole 16a with respect to the second plane P2 is V2b, the volume V2 is expressed by the following equation (4). expressed.
V2 = V2a-V2b ... (4)

Assuming that the area of the lower surface 17b of the nickel foil 17 surrounded by the inner peripheral surface 16b of the frame body 16 and the second plane P2 is S2 and the distance between the adjacent nickel foils 17 is H, the volume V2a is as follows. It is represented by (5).
V2a = S2 × H ... (5)

Assuming that the volume of the rectangular parallelepiped region surrounded by the outer surface of the portion of the separator 14 located on the same side as the communication hole 16a with respect to the second plane P2 and the second plane P2 is V2s and the porosity of the separator 14 is ε. The volume V2b is represented by the following formula (6).
V2b = V2s × (1-ε)… (6)

The volume V1 and the volume V2 can be adjusted by the size of the area S1 and the area S2. The area S1 is larger than the area S2 and may be 5 times or more or 10 times or less the area S2. The area S1 and the area S2 may be adjusted depending on the range on which the negative electrode active material for the negative electrode 19 is applied on the lower surface 17b of the nickel foil 17, or a part of the range of the applied negative electrode active material is peeled off. It may be adjusted by.

According to the above-mentioned bipolar battery 2, when gas G is generated from the positive electrode 18 or the negative electrode 19 and the pressure of the internal space V rises, the gas G goes from the second portion R2 having a small volume toward the first portion R1 having a large volume. Flows (see FIG. 5). Along with the flow (convection) of the gas G, the electrolytic solution in the internal space V moves away from the communication hole 16a in the X-axis direction. Therefore, even if the pressure in the internal space V rises and the pressure regulating valve 12 opens, the electrolytic solution in the internal space V is unlikely to be discharged from the pressure regulating valve 12. Even when the electrolytic solution is discharged from the pressure regulating valve 12, the amount of the discharged electrolytic solution can be reduced.

Further, when the volume V1 of the first portion R1 of the internal space V is 5 times or more the volume V2 of the second portion R2, the amount of the electrolytic solution contained in the first portion R1 can be increased, so that the second portion R2 The amount of electrolyte contained in the can be reduced. As a result, the discharge of the electrolytic solution from the pressure regulating valve 12 is further suppressed.

See FIG. 1 again. As shown in FIG. 1, when viewed from the Z-axis direction, the first portions R1 of the plurality of bipolar batteries 2 overlap each other at least partially. In the present embodiment, the first portion R1 of one bipolar battery 2 overlaps with the first portion R1 of the other bipolar battery 2. Further, a plurality of first portions R1 in each bipolar battery 2 also overlap each other. Similarly, when viewed from the Z-axis direction, the second portion R2 of the plurality of bipolar batteries 2 overlaps each other at least partially. In the present embodiment, the second portion R2 of one bipolar battery 2 overlaps with the second portion R2 of the other bipolar battery 2. Further, a plurality of second portions R2 in each bipolar battery 2 also overlap each other. The pressure regulating valve 12 of each bipolar battery 2 is provided at the end of the same side of both ends of the bipolar battery 2 in the X-axis direction.

When the first portion R1 and the second portion R2 overlap each other when viewed from the Z-axis direction, when a load is applied to the bipolar battery 2 by the restraint unit 6, the second portion R2 is compared with the first portion R1. The load applied to is relatively small. Therefore, the load applied to each bipolar battery 2 varies widely. On the other hand, when the plurality of first portions R1 are at least partially overlapped with each other when viewed from the Z-axis direction, the load applied to the first portion R1 can be easily made uniform. Similarly, when the plurality of second portions R2 are at least partially overlapped with each other when viewed from the Z-axis direction, it is easy to equalize the load applied to the second portion R2.

FIG. 6 is a plan view showing a part of the battery module according to the modified example. The bipolar battery 2a shown in FIG. 6 has the same configuration as the bipolar battery 2 except that the negative electrode 19 has a groove 19t. In this modification, the negative electrode 19 has a plurality of groove portions 19t extending in the X-axis direction. Each groove portion 19t extends from the first edge portion 19e1 to the second edge portion 19e2 of the main surface 19a of the negative electrode 19. The number, width, depth, cross-sectional shape, shape of the main surface 19a, etc. of the groove portions 19t are not particularly limited. The depth of the groove 19t may be the same as the thickness of the negative electrode 19 so that the lower surface 17b of the nickel foil 17 is exposed, or may be smaller than the thickness of the negative electrode 19.

In the bipolar battery 2a, the electrolytic solution in the internal space V can move away from the communication hole 16a through the groove 19t. Therefore, the electrolytic solution contained in the second portion R2 can be quickly moved to the first portion R1. Therefore, even if the pressure in the internal space V rises in a short time and the pressure regulating valve 12 opens, the electrolytic solution in the internal space V is unlikely to be released from the pressure regulating valve 12.

Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the above embodiment.

For example, in the above embodiment, the main surface 19a has a rectangular shape, but may have other shapes such as an elliptical shape and a circular shape. When the main surface 19a has an elliptical shape, the first edge portion 19e1 is one end of the long axis of the ellipse, and the second edge portion 19e2 is the other end of the long axis of the ellipse.

Further, in the above embodiment, each of all the internal spaces V has a first portion R1 and a second portion R2, but at least one of the plurality of internal spaces V has a first portion R1 and a second portion. It may have R2.

Further, in the above embodiment, the negative electrode 19 has a groove portion 19t, but the positive electrode 18 may have a groove portion extending in the X-axis direction. In this case, the electrolytic solution in the internal space V can move away from the communication hole 16a through the groove of the positive electrode 18.

Further, in the above embodiment, the bipolar battery 2 is a nickel hydrogen secondary battery, but the bipolar battery 2 is not particularly limited to the nickel hydrogen secondary battery, and may be a lithium ion secondary battery or the like.

1 ... Power storage device, 2 ... Bipolar battery (battery module), 6 ... Restraint unit, 12 ... Pressure control valve, 13 ... Bipolar electrode, 15 ... Electrode laminate, 16 ... Frame (seal part), 16a ... Communication hole, 17 ... Nickel foil (collecting plate), 17a ... Upper surface (first surface), 17b ... Lower surface (second surface), 18 ... Positive electrode, 19 ... Negative electrode, 19a ... Main surface, 19e1 ... First edge, 19e2 ... Second edge, 19t ... groove, P1 ... first plane, P2 ... second plane, R1 ... first part, R2 ... second part, V ... internal space.

Claims (6)

An electrode laminate in which bipolar electrodes having a positive electrode formed on the first surface of the current collector plate and a negative electrode formed on the second surface of the current collector plate are laminated in the first direction, and
A seal portion arranged so as to surround the electrode laminate and having a communication hole communicated with an internal space provided between the adjacent bipolar electrodes.
A pressure regulating valve that closes the communication hole,
With
The electrolytic solution is housed in the internal space.
In the second direction orthogonal to the first direction, the communication hole is arranged between the pressure regulating valve and the internal space.
The negative electrode has a main surface that intersects the first direction.
The main surface has a first edge portion farthest from the communication hole and a second edge portion closest to the communication hole in the second direction.
The internal space is orthogonal to the second direction and is orthogonal to the second direction and is orthogonal to the first portion located on the side opposite to the communication hole with respect to the first plane including the first edge portion. It has a second portion located on the same side as the communication hole with respect to the second plane including the edge portion.
A battery module in which the volume of the first portion is larger than the volume of the second portion. The battery module according to claim 1, wherein the volume of the first portion is 5 times or more the volume of the second portion. The main surface has a rectangular shape and has a rectangular shape.
The battery module according to claim 1 or 2, wherein the main surface has a first side in the first plane and a second side in the second plane. The electrode laminate is provided with a plurality of the internal spaces.
The battery module according to any one of claims 1 to 3, wherein each of the plurality of internal spaces has the first portion and the second portion. The battery module according to any one of claims 1 to 4, wherein at least one of the positive electrode and the negative electrode has a groove extending in the second direction. A power storage device including a plurality of stacked battery modules and a restraint unit for restraining the plurality of battery modules in the stacking direction of the plurality of battery modules.
Each of the plurality of battery modules is the battery module according to any one of claims 1 to 5.
When viewed from the stacking direction, the first portions of the plurality of battery modules are at least partially overlapped with each other.
A power storage device in which the second portions of the plurality of battery modules are at least partially overlapped with each other when viewed from the stacking direction.

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