Electrode assembly

Abstract

The invention relates to an electrode assembly. The electrode assembly includes: a first current collector; a first composite material layer; a second current collector; a second composite material layer; and a diaphragm. And the first composite material layer is arranged on the first current collector. And the second composite material layer is arranged on the second current collector. And the diaphragm is arranged between the first composite material layer and the second composite material layer. And the second composite material layer comprises a groove part. And the groove part extends along the plane direction of the first composite material layer. A vent portion is formed at a position in contact with the groove portion.

Description

[0001] Cross - reference to related applications

[0002] This non - provisional application is based on Japanese Patent Application No. 2023 - 214456, filed with the Japan Patent Office on December 20, 2023, the entire content of which is incorporated herein by reference. Technical Field

[0003] The present disclosure relates to an electrode assembly. Background Art

[0004] Japanese Patent Laid - Open No. 2001 - 357836 discloses a battery including an electrode assembly. The battery includes the following elements formed by superposing a positive electrode and a negative electrode with a separator interposed therebetween, and bonding the separator to the positive electrode and the negative electrode with an adhesive layer interposed between the separator and the positive electrode and the negative electrode. Grooves are formed in the composite material surface of the positive electrode, and the positive electrode has a separator bonded thereto, with the adhesive layer interposed between the separator and the positive electrode, and the ends of the grooves reach the end side of the electrode. Japanese Patent Laid - Open No. 2001 - 357836 describes that the solvent volatilized from the adhesive layer for bonding the separator to the electrode is quickly discharged to the outside through the grooves formed in the composite material surface of the electrode, which prevents the solvent from remaining in the battery. Summary of the Invention

[0005] As the battery is used and deteriorated, gas may be generated due to side reactions in the composite material layer of the electrode assembly. The gas may remain in the composite material layer, thereby inhibiting the battery reaction.

[0006] In the electrode assembly disclosed in Japanese Patent Laid - Open No. 2001 - 357836, the gas generated on the negative electrode side when viewed from the separator cannot pass through the grooves formed in the positive electrode composite material layer on the opposite side. Therefore, the gas generated within the electrode assembly is less likely to be discharged to the outside.

[0007] In view of the above problems, the present disclosure has been made, and an object of the present disclosure is to provide an electrode assembly capable of easily discharging the gas generated within the electrode assembly to the outside.

[0008] (1) An electrode assembly according to an aspect of the present disclosure includes: a first current collector; a first composite material layer; a second current collector; a second composite material layer; and a separator. The first composite material layer is provided on the first current collector. The second composite material layer is provided on the second current collector. The separator is provided between the first composite material layer and the second composite material layer. The second composite material layer includes a groove portion extending in a plane direction of the first composite material layer. An air - vent portion is formed at a position in contact with the groove portion.

[0009] According to the structure of (1) above, by providing the groove portion, the vent portion can be easily formed as described above. Through this vent portion, the gas generated in the electrode assembly can be easily discharged to the outside.

[0010] (2) In the structure of (1) above, the groove portion can be arranged such that the second current collector is exposed toward the separator side.

[0011] According to the structure of (2) above, the cross-sectional area of the groove portion is larger in the direction in which the groove portion extends. Therefore, the flow path of the gas in the vent portion can be enlarged.

[0012] (3) In the structure of (2) above, the first composite material layer can be a negative composite material layer, and the second composite material layer can be a positive composite material layer.

[0013] According to the structure of (3) above, even when the groove portion is arranged such that the second current collector is exposed toward the separator side, deposition of a metal such as metallic lithium on the second current collector can be suppressed.

[0014] (4) In the structure of any one of (1) to (3) above, the separator can include a first vent portion as the vent portion, and the first vent portion allows gas to flow from the first composite material layer side to the second composite material layer side.

[0015] According to the structure of (4) above, the gas staying in the first composite material layer moves to the groove portion through the first vent portion. The gas that has moved to the groove portion can further move along the groove portion. Therefore, the gas generated in the first composite material layer can be easily discharged to the outside.

[0016] (5) In the structure of (4) above, the separator can include a plurality of separated separators, and the plurality of separated separators are arranged along the planar direction of the first composite material layer. The ends of the plurality of separated separators can be arranged at positions corresponding to the groove portion. The first vent portion can be the ends of the plurality of separated separators, and can be configured to allow gas to flow from the first composite material layer side through the gap between the ends to the second composite material layer side. According to the structure of (5), the first vent portion can be easily formed.

[0017] (6) In the structure of (5) above, the ends of the plurality of separated separators can overlap each other.

[0018] According to the structure of (6) above, since the ends overlap each other, even when the separator includes the first vent portion, a short circuit between the first composite material layer and the second composite material layer or the second current collector can be suppressed.

[0019] (7) In the structure according to any one of (4) to (6) above, the groove portion may linearly extend along the planar direction of the first composite material layer. The first ventilation portion may form a slit extending along the groove portion.

[0020] According to the structure of (7) above, the flow of gas in the groove portion may be a flow along the direction in which the groove portion linearly extends. Therefore, the direction of gas flow in the groove portion is stabilized. In addition, the cross-sectional area of the flow path in the first ventilation portion can be enlarged.

[0021] (8) In the structure according to any one of (1) to (3) above, the second ventilation portion may be formed as the ventilation portion. The second ventilation portion may include a first portion and a second portion, where the first portion is the portion of the diaphragm disposed at a position corresponding to the groove portion, and the second portion is the portion of the first composite material layer facing the first portion. The second ventilation portion may be configured to allow gas to flow between the first portion and the second portion along the direction in which the groove portion extends.

[0022] According to the structure of (8) above, the gas staying in the first composite material layer can move within the second ventilation portion along the direction in which the groove portion extends. Therefore, the gas generated in the first composite material layer can be easily discharged.

[0023] (9) In the structure of (8) above, the diaphragm may include a plurality of separated diaphragms, and the plurality of separated diaphragms are arranged along the planar direction of the first composite material layer. The ends of the plurality of separated diaphragms may constitute the first portion while overlapping each other.

[0024] According to the structure of (9) above, at least one of the ends is easily separated from the first composite material layer. Therefore, a gap between the first portion and the second portion can be ensured, and gas can flow more easily within the second ventilation portion.

[0025] (10) In the structure of (9) above, the groove portion may be arranged such that the second current collector is exposed toward the diaphragm side. One end of the ends of the plurality of separated diaphragms may be welded to the second current collector.

[0026] According to the structure of (10) above, the flow path of gas in the second ventilation portion can be formed more stably.

[0027] (11) In the structure of (6) or (9) above, the overlapping portions of the ends of the plurality of separated diaphragms may be partially welded to each other.

[0028] According to the structure of (11) above, even when the separator includes the plurality of separated separators, the short circuit between the first composite material layer and the second composite material layer or the second current collector through the gap between the ends can be suppressed by the above welding.

[0029] When combined with the accompanying drawings, the foregoing and other objects, features, aspects and advantages of the present disclosure will become more apparent from the following detailed description of the present disclosure. Brief Description of the Drawings

[0030] Figure 1 is a plan view showing an electrode assembly according to a first embodiment.

[0031] Figure 2 is Figure 1 a partial cross-sectional view of the electrode assembly taken along line II-II.

[0032] Figure 3 is a partial cross-sectional view of the electrode assembly, in which the gas generated in the electrode assembly according to the first embodiment is schematically shown.

[0033] Figure 4 is a partial cross-sectional view of an electrode assembly according to a second embodiment. Detailed Description of the Embodiments

[0034] Hereinafter, the electrode assembly according to each embodiment of the present disclosure will be described with reference to the accompanying drawings. In the following description of the embodiments, the same or corresponding parts in the drawings are denoted by the same reference numerals, and their description will not be repeated.

[0035] (First Embodiment)

[0036] Figure 1 is a plan view showing an electrode assembly according to a first embodiment. Figure 2 is Figure 1 a partial cross-sectional view of the electrode assembly taken along line II-II.

[0037] As Figure 1 and Figure 2 shown, the electrode assembly 1 includes a first current collector 10, a first composite material layer 20, a second current collector 30, a second composite material layer 40, and a separator 50. A plurality of vent portions 100 are formed in the electrode assembly 1.

[0038] The electrode assembly 1 according to the present disclosure can be an electrode assembly 1 for a battery such as a non-aqueous electrolyte secondary battery. The electrode assembly 1 can be used in a battery in a wound state. A plurality of electrode assemblies 1 can be used in a battery in a stacked state. The electrode assembly 1 can be used in a battery in a zigzag state.

[0039] The electrode assembly 1 can be accommodated in, for example, a housing (not shown) filled with an electrolyte therein or a laminated film (not shown). Thus, a power storage unit or a power storage device including the electrode assembly 1 and the housing or the laminated film can be manufactured. The power storage unit or the power storage device can be mounted on a vehicle.

[0040] As Figure 1 and Figure 2 shown, the first current collector 10 extends in a planar shape. The first current collector 10 has a plate-like, sheet-like, or foil-like outer shape. In the present embodiment, the first current collector 10 has a foil-like outer shape. When viewed from a direction orthogonal to the planar direction of the first current collector 10, the first current collector 10 has a rectangular outer shape.

[0041] The first current collector 10 is made of metal. In the present embodiment, the first current collector 10 is made of copper.

[0042] The first composite layer 20 is provided on the first current collector 10. The first composite layer 20 extends in a planar shape along the planar direction of the first current collector 10. When viewed from a direction orthogonal to the planar direction of the first composite layer 20, the first composite layer 20 has a rectangular outer shape. The outer shape of the first composite layer 20 follows the outer shape of the first current collector 10.

[0043] In the present embodiment, the first composite layer 20 is a negative electrode composite layer. The negative electrode composite layer includes a negative electrode active material, a binder, and the like. Examples of the negative electrode active material include graphite and the like.

[0044] The second current collector 30 extends substantially parallel to the first current collector 10. The second current collector 30 has a plate-like, sheet-like, or foil-like outer shape. In the present embodiment, the second current collector 30 has a foil-like outer shape. When viewed from a direction orthogonal to the planar direction of the second current collector 30, the outer edge of the second current collector 30 substantially overlaps with the outer edge of the first current collector 10. The second current collector 30 has a substantially rectangular outer shape.

[0045] The second current collector 30 is made of metal. In the present embodiment, the second current collector 30 is made of aluminum or an aluminum alloy.

[0046] The second composite layer 40 is provided on the second current collector 30. The second composite layer 40 extends in a planar shape along the planar direction of the first composite layer 20. When viewed from a direction orthogonal to the planar direction of the first composite layer 20, the outer edge of the second composite layer 40 is located inside the outer edge of the first composite layer 20. Thus, when the electrode assembly 1 is used in a lithium ion battery or the like, deposition of metallic lithium on the first current collector 10 can be suppressed.

[0047] As Figure 1As shown, in this embodiment, the second composite material layer 40 has a plurality of groove portions 41. The plurality of groove portions 41 extend in the plane direction of the first composite material layer 20. Specifically, the plurality of groove portions 41 linearly extend in the plane direction of the first composite material layer 20. Therefore, the flow of gas in each groove portion 41 may be a flow along the direction in which the groove portion 41 linearly extends. Thus, the direction of gas flow in each groove portion 41 is stabilized. The gas flow in each groove portion 41 will be described below.

[0048] In Figure 1 it, the first direction D1 and the second direction D2 are shown as the plane direction of the first composite material layer 20. The second direction D2 is a direction orthogonal to the first direction D1. The plurality of groove portions 41 extend parallel to the second direction D2. The plurality of groove portions 41 extend along the second direction D2 from one edge of the second composite material layer 40 to the other edge.

[0049] As Figure 2 shown, in this embodiment, the plurality of groove portions 41 are arranged such that the second current collector 30 is exposed toward the separator 50 side in each of the plurality of groove portions 41. Therefore, the cross-sectional area of each groove portion 41 is larger in the direction in which the groove portion 41 extends.

[0050] The second composite material layer 40 has a plurality of separated second composite material layers 40D. The plurality of separated second composite material layers 40D are arranged along the first direction D1. A pair of adjacent separated second composite material layers 40D are arranged with a groove portion 41 interposed therebetween.

[0051] However, the groove portion 41 does not necessarily need to be arranged such that the second current collector 30 is exposed in each groove portion 41. In other words, each groove portion 41 may have a recessed strip-like shape that is at least open toward the separator 50 side.

[0052] Preferably, only one first composite material layer 20 should be provided for the above-mentioned plurality of separated second composite material layers 40D. This makes it possible to increase the energy density of the electrode assembly 1. In addition, preferably, the first composite material layer 20 should not include grooves or the like formed such that the first current collector 10 is exposed at positions corresponding to each groove portion 41. This makes it possible to increase the energy density of the electrode assembly 1.

[0053] In this embodiment, the second composite material layer 40 is a positive electrode composite material layer. Therefore, even when the groove portion 41 is provided such that the second current collector 30 is exposed toward the separator 50 side, deposition of a metal such as metallic lithium on the second current collector 30 can be suppressed. The positive electrode composite material layer includes a positive electrode active material, a binder, and the like. Examples of the positive electrode active material include LiCoO2, LiNO2, LiMn2O4, and the like. It should be noted that the first composite material layer 20 may be a positive electrode composite material layer, and the second composite material layer 40 may be a negative electrode composite material layer.

[0054] As Figure 2 shown, the separator 50 is disposed between the first composite material layer 20 and the second composite material layer 40. The separator 50 separates the first current collector 10 and the first composite material layer 20 from the second current collector 30 and the second composite material layer 40. The separator 50 is made of an insulating material. The separator 50 may be a porous membrane. In this embodiment, the separator 50 has minute gaps that allow the transport of ions, such as lithium ions.

[0055] The separator 50 includes a plurality of first vent portions 110 as the plurality of vent portions 100. Each first vent portion 110 is configured to allow gas to flow from the first composite material layer 20 side toward the second composite material layer 40 side. The plurality of first vent portions 110 are respectively formed at positions corresponding to the plurality of groove portions 41. Each first vent portion 110 forms a slit extending along the corresponding groove portion 41. Therefore, the cross-sectional area of the flow path in each first vent portion 110 can be enlarged. The specific structure of the slit will be described below.

[0056] In this embodiment, the separator 50 includes a plurality of separated separators 50D. The plurality of separated separators 50D are arranged in the planar direction of the first composite material layer 20. Specifically, the plurality of separated separators 50D are arranged along the first direction D1. The end portions of the plurality of separated separators 50D adjacent to each other in the first direction D1 overlap each other.

[0057] Next, a pair of separated separators 50A and 50B adjacent to each other among the plurality of separated separators 50D will be described. A pair of separated separators 50D other than this pair of separated separators 50A and 50B may also have the same configuration as the pair of separated separators 50A and 50B.

[0058] In the present embodiment, the ends 52A and 52B of the plurality of separated diaphragms 50A and 50B are provided at positions corresponding to the groove portion 41. In the present embodiment, the first ventilation portion 110 is specifically the ends 52A and 52B of the plurality of separated diaphragms 50A and 50B. The first ventilation portion 110 is configured to allow gas to flow from the first composite material layer 20 side through the gap between the ends 52A and 52B to the second composite material layer 40 side. Therefore, the first ventilation portion 110 can be easily formed. The slit formed by the first ventilation portion 110 is the gap between the ends 52A and 52B. It should be noted that the diaphragm 50 may be formed of one member. When the diaphragm 50 is formed of one member, the slit formed by the first ventilation portion 110 may be a through hole passing through the diaphragm 50.

[0059] In the present embodiment, the ends 52A and 52B are positioned to overlap the groove portion 41 in a direction orthogonal to the plane direction of the first composite material layer 20. As a result, even when the width of the groove portion 41 decreases due to the volume change of the second composite material layer 40, a short circuit between the first composite material layer 20 and the second composite material layer 40 can be suppressed. It should be noted that the edges of the ends 52A and 52B may be set to be flush with the two edges of the groove portion 41 in the first direction D1, respectively.

[0060] The ends 52A and 52B of the plurality of separated diaphragms 50A and 50B overlap each other. Since the ends 52A and 52B overlap each other as described above, even when the diaphragm 50 has the first ventilation portion 110, a short circuit between the first composite material layer 20 and the second composite material layer 40 or the second current collector can be suppressed. In addition, since the ends 52A and 52B overlap each other, at least one of the ends 52A and 52B is likely to be separated from the first composite material layer 20. However, the ends 52A and 52B of the plurality of separated diaphragms 50A and 50B may face each other in the first direction D1.

[0061] Preferably, the overlapping portion of the plurality of separated diaphragms 50A and 50B should be located in the central region CA of the groove portion 41. This makes it possible to suppress the case where any one of the ends 52A and 52B of the separated diaphragms 50A and 50B cannot be provided in the groove portion 41, even when there are manufacturing errors in the dimensions of the plurality of separated diaphragms 50A and 50B. The central region CA of the groove portion 41 refers to the region other than the regions OA on both sides when the groove portion 41 is divided into four regions along the first direction D1. It should be noted that the overlapping portion of the above-mentioned plurality of separated diaphragms 50A and 50B may be located in different regions OA other than the central region CA of the groove portion 41.

[0062] The overlapping portions of the ends 52A and 52B of the plurality of separated diaphragms 50A and 50B can be partially welded to each other. Thus, even when the diaphragm 50 includes the plurality of separated diaphragms 50A and 50B, a short circuit between the first composite material layer 20 and the second composite material layer 40 or the second current collector 30 through the gap between the ends 52A and 52B can be suppressed by the above welding. However, the ends 52A and 52B of the plurality of separated diaphragms 50A and 50B can partially include portions that are not welded to each other. Thus, in the overlapping portion of the plurality of separated diaphragms 50A and 50B, gas can flow from the first composite material layer 20 side through the gap between the ends 52A and 52B to the second composite material layer 40 side.

[0063] In the electrode assembly 1, the number of the plurality of separated diaphragms 50D can be the same as the number of the plurality of separated second composite material layers 40D. Thus, the plurality of first vent portions 110 can be easily formed to correspond one-to-one to the plurality of groove portions 41. Thus, the discharge of gas through the groove portions 41 and the first vent portions 110 can be finely performed at a plurality of positions (details will be described below). The number of the plurality of separated diaphragms 50D can be different from the number of the plurality of separated second composite material layers 40D.

[0064] Furthermore, in the electrode assembly 1 according to the present embodiment, the second vent portion 120 is formed as the vent portion 100. The second vent portion 120 includes a first portion 121 and a second portion 122, where the first portion 121 is the portion of the diaphragm 50 provided at a position corresponding to the groove portion 41, and the second portion 122 is the portion of the first composite material layer 20 facing the first portion 121. The second vent portion 120 is configured to allow gas to flow between the first portion 121 and the second portion 122 in a direction extending along the groove portion 41. Specifically, the second vent portion 120 is configured to allow gas to flow between the first portion 121 and the second portion 122 in the second direction D2.

[0065] In the present embodiment, the ends 52A and 52B of the plurality of separated diaphragms 50A and 50B constitute the first portion 121 while overlapping each other. Specifically, the first portion 121 is the first vent portion 110.

[0066] As described above, in the electrode assembly 1 according to the present embodiment, both the first vent portion 110 and the second vent portion 120 are formed as the vent portion 100. However, only one of the first vent portion 110 and the second vent portion 120 can be formed.

[0067] For example, when no gap is formed between the separator 50 and the first composite material layer 20, the second vent portion 120 is not formed. However, even in such a case, the first vent portion 110 can be formed by facing the ends 52A and 52B of the plurality of separated separators 50A and 50B constituting the first vent portion 110 with each other in the first direction D1. In addition, in the above case, the first vent portion 110 can be formed by forming the separator 50 with one member and forming the above-described slit passing through the separator 50.

[0068] When the ends 52A and 52B of the separated separators 50A and 50B are completely welded to each other along the second direction D2, for example, the first vent portion 110 is not formed. Even in such a case, the second vent portion 120 can be formed by overlapping the ends 52A and 52B of the separated separators 50A and 50B with each other.

[0069] Next, the flow path of the gas when gas is generated in the first composite material layer 20 will be described. Figure 3 is a partial cross-sectional view of the electrode assembly, schematically showing the gas generated in the electrode assembly according to the first embodiment. Figure 3 Shows the same Figure 2 electrode assembly in the cross-sectional view. In Figure 3 , the gas G generated in the first composite material layer 20 is shown. The moving direction of the gas G is also schematically shown by the arrow provided to the gas G.

[0070] As Figure 3 shown, the gas G generated in the first composite material layer 20 stays in the gap between the separator 50 and the first composite material layer 20. Specifically, the gas G stays in the gap between the first portion 121 and the second portion 122 of the second vent portion 120. In addition, the gas G moves to the trench portion 41 through the gap between the ends 52A and 52B in the first vent portion 110. The gas G that has moved to the trench portion 41 moves along the second direction D2 (see Figure 1 ). Then, the gas G can be discharged to the outside of the electrode assembly 1 from any one of the ends of the trench portion 41 in the second direction D2.

[0071] In addition, the gas G generated in the first composite material layer 20 and continuously staying in the gap between the first portion 121 and the second portion 122 of the second vent portion 120 also moves in the direction along the trench portion 41. That is, the gas G in the gap between the first portion 121 and the second portion 122 also moves along the second direction D2 (see Figure 1 ). Then, the gas G can also be discharged to the outside of the electrode assembly 1 from any one of the ends of the gap between the first portion 121 and the second portion 122 in the second direction D2.

[0072] As described above, in the electrode assembly 1 according to the first embodiment of the present disclosure, the ventilation portion 100 is formed at a position in contact with the groove portion 41.

[0073] According to the above configuration, by providing the groove portion 41, the ventilation portion 100 can be easily formed. Through the ventilation portion 100, the gas generated in the electrode assembly 1 can be easily discharged to the outside.

[0074] In addition, the separator 50 includes a first ventilation portion 110 as the ventilation portion 100 that allows gas to flow from the first composite material layer 20 side to the second composite material layer 40 side.

[0075] According to the above configuration, the gas staying in the first composite material layer 20 moves to the groove portion 41 through the first ventilation portion 110. The gas that has moved to the groove portion 41 can further move along the groove portion 41. Therefore, the gas generated in the first composite material layer 20 can be easily discharged to the outside.

[0076] Furthermore, in the electrode assembly 1, a second ventilation portion 120 is formed as the ventilation portion 100. The second ventilation portion 120 includes a first portion 121 and a second portion 122, where the first portion 121 is the portion of the separator 50 provided at a position corresponding to the groove portion 41, and the second portion 122 is the portion of the first composite material layer 20 facing the first portion 121. The second ventilation portion 120 is configured to allow gas to flow between the first portion 121 and the second portion 122 in the direction extending along the groove portion 41.

[0077] According to the above configuration, the gas staying in the first composite material layer 20 can move within the second ventilation portion 120 in the direction extending along the groove portion 41. Therefore, the gas generated in the first composite material layer 20 can be easily discharged.

[0078] (Second Embodiment)

[0079] Next, the electrode assembly according to the second embodiment will be described. In the electrode assembly according to the second embodiment, the divided separators are different from the divided separators 50A and 50B of the electrode assembly 1 according to the first embodiment. The description of the same configurations and effects as those of the electrode assembly 1 according to the first embodiment will not be repeated.

[0080] Figure 4 is a partial cross-sectional view of the electrode assembly according to the second embodiment. Figure 4 Shown in the same cross-sectional view as the electrode assembly 1 of the first embodiment in Figure 2 is the electrode assembly 1a according to the second embodiment.

[0081] As Figure 4As shown, one of the ends 52Aa and 52Ba of the plurality of separated diaphragms 50A and 50B is welded to the second current collector 30. According to this configuration, a short circuit between the first composite material layer 20 and the second current collector 30 can be further suppressed. In addition, the flow path of the gas in the second ventilation portion 120 can be formed more stably. In this embodiment, the end 52Ba is welded to the second current collector 30. The end 52Aa may also be partially welded to the second current collector 30.

[0082] Although embodiments of the present disclosure have been described, it should be understood that the embodiments disclosed herein are illustrative and non-limiting in every aspect. The scope of the present disclosure is defined by the terms of the claims and is intended to include any variations within the scope and meaning equivalent to the terms of the claims.

Claims

1. An electrode assembly, comprising: First Collector Fluid; a first composite material layer, the first composite material layer being disposed on the first current collector; Second episode fluid; a second composite material layer, the second composite material layer being disposed on the second current collector; as well as a diaphragm disposed between the first composite material layer and the second composite material layer, wherein The second composite material layer includes a groove portion extending along a plane direction of the first composite material layer, and The vent portion is formed at a position in contact with the groove portion.

2. The electrode assembly according to claim 1, wherein: The groove portion is provided so that the second current collector is exposed toward the separator side.

3. The electrode assembly according to claim 2, wherein: The first composite material layer is a negative electrode composite material layer, and The second composite material layer is a positive electrode composite material layer.

4. The electrode assembly according to claim 1, wherein: The separator includes a first vent portion as the vent portion that allows gas to flow from a first composite material layer side to a second composite material layer side.

5. The electrode assembly according to claim 4, wherein: The diaphragm includes a plurality of divided diaphragms, and the plurality of divided diaphragms are arranged along a plane direction of the first composite material layer. The ends of the plurality of divided diaphragms are disposed at positions corresponding to the groove portions, and The first vent is an end portion of the plurality of divided membranes, and is configured to allow gas to flow from the first composite material layer side to the second composite material layer side through a gap between the end portions.

6. The electrode assembly according to claim 5, wherein: End portions of the plurality of divided diaphragms overlap with each other.

7. The electrode assembly according to claim 4, wherein: The groove portion extends linearly along the plane direction of the first composite material layer, and The first ventilation portion forms a slit extending along the groove portion.

8. The electrode assembly according to claim 1, wherein: A second vent is formed as the vent, the second vent includes a first portion and a second portion, wherein the first portion is a portion of the diaphragm disposed at a position corresponding to the groove portion, and the second portion is a portion of the first composite material layer facing the first portion, and The second vent portion is configured to allow gas to flow between the first portion and the second portion along a direction in which the groove portion extends.

9. The electrode assembly according to claim 8, wherein: The diaphragm includes a plurality of divided diaphragms, and the plurality of divided diaphragms are arranged along a plane direction of the first composite material layer, and End portions of the plurality of divided diaphragms constitute the first portion while overlapping each other.

10. The electrode assembly according to claim 9, wherein: The groove portion is configured such that the second current collector is exposed toward the separator side, and One of the ends of the plurality of divided separators is welded to the second current collector.

11. The electrode assembly according to claim 6 or 9, wherein: The mutually overlapping portions of the ends of the plurality of divided diaphragms are partially welded to each other.

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