Electrode body and bipolar battery

Abstract

To provide an electrode body which includes a current collector laminate that is easily disassembled and maintains quality as an electrode body.SOLUTION: A current collector laminate and a seal material that seals the current collector laminate, wherein the current collector laminate has a first metal foil, an adhesive layer, and a second metal foil in this order, the adhesive layer has a defect portion extending inward from an end face in an in-plane direction of the current collector laminate, and the seal material is provided so as to cover the end face of the current collector laminate and continuously cover a part of an upper surface and a part of a lower surface of the current collector laminate, the seal material covers at least an in-plane region of the upper surface and the lower surface, the in-plane region corresponding to the defect portion.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an electrode assembly and a bipolar battery. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2023-147314 discloses a fuel cell stack that is disassembled by cutting a sealing sheet. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-147314 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need to recover various materials from discarded batteries and recycle them, which has led to a demand for batteries that are easy to disassemble.

[0005] Bipolar batteries that are partitioned into multiple cells by sealing the spaces between each electrode body are being studied. These bipolar batteries use a current collector laminate made of multiple metal foils bonded together. From the viewpoint of resource recycling, a current collector laminate that allows the multiple metal foils to be easily separated is desired.

[0006] An object of the present disclosure is to provide an electrode assembly that includes a current collecting laminate that is easily separated and that maintains the quality of the electrode assembly. [Means for solving the problem]

[0007] 1. One aspect of the present disclosure is an electrode assembly including a current collecting laminate and a sealing material that seals the current collecting laminate, wherein the current collecting laminate has a first metal foil, an adhesive layer, and a second metal foil, in that order, the adhesive layer having a missing portion extending inward from an end face in an in-plane direction of the current collecting laminate, the sealing material covering the end face of the current collecting laminate and continuously covering a portion of the upper surface and a portion of the lower surface of the current collecting laminate, and the sealing material covering at least an in-plane region of the upper surface and the lower surface that corresponds to the missing portion.

[0008] The current collecting laminate used in the electrode assembly of the present disclosure allows the first metal foil and the second metal foil to be easily separated using the missing portion of the adhesive layer as a gripping area. The electrode assembly includes a sealing material that seals the current collecting laminate. The sealing material covers at least the in-plane areas of the upper and lower surfaces of the current collecting laminate that correspond to the missing portion of the adhesive layer. Therefore, even if there are pinholes in the first metal foil and / or the second metal foil, the adhesive layer can prevent the electrolyte from permeating the current collecting laminate in the area where the adhesive layer is present, and the sealing material can prevent the electrolyte from permeating the current collecting laminate in the missing portion where no adhesive layer is present, thereby maintaining the quality of the electrode assembly.

[0009] 2. The electrode body described in "1" above may have, for example, the following configuration: the cutout portion extends in the in-plane direction by a length of less than 5 mm from the end face, and the sealing material extends in the in-plane direction on the upper and lower faces by a length of 5 mm or more from the end face.

[0010] 3. The electrode body described in "1" or "2" above may have, for example, the following configuration: It further includes a positive electrode layer and a negative electrode layer, and in an in-plane region where the sealing material is not provided, the positive electrode layer, the first metal foil, the adhesive layer, the second metal foil, and the negative electrode layer are laminated in this order.

[0011] 4. The electrode body described in "3" above may have, for example, the following configuration: The first metal foil contains aluminum, and the second metal foil contains copper.

[0012] 5. Another aspect of the present disclosure is a bipolar battery comprising the electrode assembly according to "3" or "4" above and a separator, wherein the electrode assembly and the separator are alternately stacked.

[0013] Hereinafter, one embodiment of the present disclosure (hereinafter, may be abbreviated as "the present embodiment") will be described. However, this embodiment does not limit the technical scope of the present disclosure. This embodiment is illustrative in all respects. This embodiment is non-restrictive. The technical scope of the present disclosure encompasses all modifications within the meaning and scope equivalent to the claims. For example, it is also intended from the beginning that any configuration may be extracted from this embodiment and arbitrarily combined. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic perspective view of a bipolar battery according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Figure 3] FIG. 2 is a schematic cross-sectional view showing an electrode body and a sealing material in the present embodiment. [Figure 4] FIG. 4 is a partially enlarged view of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0015] -Terms and phrases- Geometric terms should not be interpreted in a strict sense. Examples of geometric terms include "parallel," "perpendicular," and the like. For example, directions, angles, distances, and the like may be displaced relative to one another as long as substantially the same or similar functions are obtained. Geometric terms may include, for example, tolerances, errors, and the like in design, work, manufacturing, and the like. The dimensional relationships in each figure may not match the actual dimensional relationships. The dimensional relationships in each figure may be changed to aid the reader's understanding. For example, length, width, thickness, and the like may be changed. Some components may be omitted.

[0016] The "perpendicular to the surface" refers to the normal direction to the surface of a sheet-like member (e.g., foil, electrode body, etc.). The "in-plane direction" refers to any direction perpendicular to the perpendicular to the surface. In the drawings of this embodiment, the Z-axis direction corresponds to the perpendicular to the surface. The X-axis direction and the Y-axis direction are examples of in-plane directions.

[0017] -Bipolar battery- FIG. 1 is a schematic perspective view of a bipolar battery according to this embodiment. FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. 1. The bipolar battery 100 includes an exterior body 90 and a power generating element 50. The exterior body 90 houses the power generating element 50. The exterior body 90 may include, for example, a first current collecting plate 91, a first laminate film 92, a second laminate film 93, and a second current collecting plate 94. The first laminate film 92 and the second laminate film 93 are bonded to each other at their in-plane end portions. At the bond between the first laminate film 92 and the second laminate film 93, a sealant (not shown) may be interposed between the first laminate film 92 and the second laminate film 93.

[0018] The first current collector plate 91 and the second current collector plate 94 are joined to the power generating element 50 at their ends in the stacking direction (Z-axis direction). A first laminate film 92 is joined to the first current collector plate 91. A second laminate film 93 is joined to the second current collector plate 94. A sealant (not shown) may be interposed between the current collector plate and the laminate film at the joint between the current collector plate and the laminate film.

[0019] The power generating element 50 includes a plurality of electrode bodies 10. The plurality of electrode bodies 10 are stacked in the direction perpendicular to the plane (Z-axis direction). Each of the plurality of electrode bodies 10 includes a positive electrode layer 11, a current collecting laminate 13, and a negative electrode layer 12, in this order, in the direction perpendicular to the plane. In an in-plane direction (e.g., the X-axis direction), the current collecting laminate 13 extends outward relative to the positive electrode layer 11 and the negative electrode layer 12. For example, the current collecting laminate 13 may extend outward relative to the positive electrode layer 11 and the negative electrode layer 12 over the entire periphery in the in-plane direction.

[0020] The power generating element 50 includes a sealing material 30. The sealing material 30 is joined to the current collecting laminate 13 at the end in the in-plane direction. The sealing material 30 may be, for example, heat-welded to the current collecting laminate 13. For example, the sealing material 30 may be disposed around the entire periphery in the in-plane direction. The sealing material 30 seals between adjacent current collecting laminates 13 in the direction perpendicular to the plane. The sealing material 30 seals between the current collecting laminates 13, thereby dividing them into cells. A cell is the smallest unit of the power generating element 50. Because the bipolar battery 100 includes multiple cells, it may also be called a "bipolar module."

[0021] -Current collecting laminate and sealing material- Fig. 3 is a schematic cross-sectional view showing the electrode body and sealing material in this embodiment. Fig. 4 is a partially enlarged view of the joint between the electrode body and sealing material shown in Fig. 3. As shown in Fig. 3, the current collecting laminate 13 may include, for example, a first metal foil 13a, an adhesive layer 13c, and a second metal foil 13b in this order in the direction perpendicular to the surface.

[0022] The adhesive layer 13c bonds the first metal foil 13a and the second metal foil 13b together. The adhesive layer 13c has a missing portion 14 extending inward from an end face 13e of the current collecting laminate 13 in an in-plane direction. The sealant 30 covers the end face 13e of the current collecting laminate 13 and continuously covers a portion of the upper face 13f and a portion of the lower face 13g of the current collecting laminate 13. The sealant 30 covers at least the in-plane regions of the upper face 13f and the lower face 13g that correspond to the missing portion 14. That is, in any cross section perpendicular to the plane, the length d1 extending in the in-plane direction from the end face 13e of the missing portion 14 of the adhesive layer 13c and the length d2 extending in the in-plane direction from the end face 13e of the region where the sealant 30 covers the upper face 13f and the lower face 13g of the current collecting laminate 13 satisfy the relationship d2 > d1. The length d1 is preferably less than 5 mm, and may be less than 4 mm, or may be 2 mm or more, or 3 mm or more. The length d2 is not limited as long as it satisfies the relationship d2>d1, and may be, for example, 5 mm or more, or 30 mm or less, or 10 mm or less.

[0023] According to this embodiment, when disassembling the bipolar battery 100, the first metal foil 13a and the second metal foil 13b can be easily separated by using the missing portions 14 as gripping points in the current collector laminate 13. Furthermore, although the first metal foil 13a and the second metal foil 13b have regions where the adhesive layer 13c is not present, the presence of the sealing material 30 in these regions allows the quality of the electrode assembly to be maintained.

[0024] The first metal foil 13a and / or the second metal foil 13b may have pinholes. In the present embodiment, even if the first metal foil 13a and / or the second metal foil 13b have pinholes, the adhesive layer 13c can prevent the electrolyte from permeating through the current collecting laminate 13 in the region where the adhesive layer 13c is present, and the sealing material 30 can prevent the electrolyte from permeating through the current collecting laminate 13 in the defect portion 14 where the adhesive layer 13c is not present. Therefore, even if the defect portion 14 is present, the quality of the electrode body 10 is not reduced, and the quality of the electrode body 10 can be maintained.

[0025] The adhesive layer 13c may contain, for example, a conductive adhesive, etc. The conductive adhesive is not particularly limited as long as it has conductivity and adhesiveness, but typically contains a conductive material and a resin.

[0026] The conductive material contained in the conductive adhesive is not limited as long as it is a conductive material, and examples thereof include metal particles and carbon materials. Typically, either metal particles or carbon materials are used, but both may be used in combination. Examples of resins contained in the conductive adhesive include phenolic resins, epoxy resins, melamine resins, urea resins, urethane resins, alkyd resins, silicone resins, unsaturated polyester resins, polyolefin resins, polyimides, and acrylic resins. These may be used alone or in combination. Among these, it is preferable to use at least one resin selected from the group consisting of epoxy resins, urethane resins, silicone resins, polyolefin resins, and acrylic resins. By using resins from this group, more suitable adhesive strength and conductivity can be achieved. Thermosetting resins may also be used as the resin contained in the conductive adhesive.

[0027] The thickness of adhesive layer 13c may be, for example, 0.5 μm or more, 1 μm or more, 2 μm or more, or 3 μm or more, and may be, for example, 10 μm or less, 5 μm or less, or 3 μm or less.

[0028] The first metal foil 13a is a positive electrode current collector foil. The first metal foil 13a may contain, for example, aluminum (Al). The first metal foil 13a may contain, for example, Al foil, Al alloy foil, titanium foil, stainless steel foil, etc. The thickness of the first metal foil 13a may be, for example, 5 μm or more, 10 μm or more, 25 μm or more, 50 μm or more, or 75 μm or more. The thickness of the first metal foil 13a may be, for example, 100 μm or less, 75 μm or less, or 50 μm or less.

[0029] The second metal foil 13b is a negative electrode current collector foil. The second metal foil 13b may contain, for example, copper (Cu). The second metal foil 13b may contain, for example, Cu foil, Cu alloy foil, Ni foil, etc. The second metal foil 13b may be thinner than the first metal foil 13a. The thickness of the second metal foil 13b may be, for example, 2 μm or more, 4 μm or more, 6 μm or more, 8 μm or more, or 10 μm or more. The thickness of the second metal foil 13b may be, for example, 20 μm or less, 15 μm or less, 12 μm or less, 10 μm or less, or 8 μm or less.

[0030] The current collecting laminate 13 may include a carbon coating layer 13d. At least a portion of the carbon coating layer 13d may be disposed at the bonding interface between the current collecting laminate 13 and the sealing material 30. For example, the carbon coating layer 13d may cover the entire surface of the current collecting laminate 13. The carbon coating layer 13d may be formed on only one side of the current collecting laminate 13. The carbon coating layer 13d may be formed on both sides of the current collecting laminate 13. The carbon coating layer 13d may be formed only at the bonding interface between the current collecting laminate 13 and the sealing material 30.

[0031] The sealing material 30 may contain, for example, at least one selected from the group consisting of polyolefin resin, polyamide resin, acrylic resin, and fluororesin. The sealing material 30 may contain, for example, at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP). The thickness of the sealing material 30 in the in-plane outward direction from the end face 13e may be, for example, 5 mm or less, 3 mm or less, 1 mm or less, 0.8 mm or less, 0.6 mm or less, 0.4 mm or less, or 0.2 mm or less. The thickness of the sealing material 30 in the in-plane outward direction from the end face 13e may be, for example, 0.01 mm or more, 0.05 mm or more, 0.1 mm or more, or 0.2 mm or more.

[0032] The carbon coating layer 13d includes a carbon material. The carbon material may include, for example, at least one selected from the group consisting of carbon black, graphite, carbon fiber, carbon nanotubes, and graphene flakes. The carbon coating layer 13d may further include, for example, a binder in addition to the carbon material. The binder may include, for example, polyvinylidene fluoride (PVDF). For example, the carbon coating layer 13d may include, by mass fraction, 10 to 90% of the carbon material and the remainder being the binder. The carbon coating layer 13d may be formed, for example, by gravure coating.

[0033] -others- The electrode body 10 may further include a positive electrode layer 11 and a negative electrode layer 12. In the in-plane region of the electrode body 10 where the sealing material 30 is not provided, the positive electrode layer 11, the first metal foil 13a, the adhesive layer 13c, the second metal foil 13b, and the negative electrode layer 12 are laminated in this order.

[0034] The positive electrode layer 11 is attached to one surface (first metal foil 13a) of the current collector laminate 13. A carbon coating layer 13d may be interposed between the positive electrode layer 11 and the first metal foil 13a. The positive electrode layer 11 includes a positive electrode active material. The positive electrode active material may include, for example, a lithium nickel composite oxide, an olivine-type phosphate compound, or the like. The positive electrode layer 11 may further include a conductive material and a binder. The conductive material may include, for example, carbon black, or the like. The binder may include, for example, PVDF, or the like.

[0035] The negative electrode layer 12 is attached to one surface (second metal foil 13b) of the current collector laminate 13. A carbon coating layer 13d may be interposed between the negative electrode layer 12 and the second metal foil 13b. The negative electrode layer 12 may have, for example, a larger area than the positive electrode layer 11. The negative electrode layer 12 includes a negative electrode active material. The negative electrode active material may include, for example, graphite, silicon, silicon oxide, a silicon-carbon composite (Si / C material), or the like. The negative electrode layer 12 may also further include a conductive material and a binder. The conductive material is the same as that of the positive electrode layer 11. The binder may include, for example, carboxymethyl cellulose, styrene-butadiene rubber, or the like.

[0036] The electrode body 10 can be formed, for example, by bonding a first metal foil 13a and a second metal foil 13b together via an adhesive layer 13c, and then attaching a positive electrode layer 11 to the side of the first metal foil 13a opposite the adhesive layer 13c, and an negative electrode layer 12 to the side of the second metal foil 13b opposite the adhesive layer 13c. The adhesive is applied so as to leave an uncoated portion at the periphery, and the uncoated portion becomes the missing portion 14. A gravure coater, for example, can be used as an adhesive applicator.

[0037] In the bipolar battery 100, the separator 20 is interposed between the electrode assemblies 10. That is, in the bipolar battery 100, the electrode assemblies 10 and the separators 20 are alternately stacked. The separator 20 electrically separates the positive electrode layer 11 from the negative electrode layer 12. The separator 20 may include, for example, a porous resin membrane.

[0038] The electrolyte (not shown) is a liquid electrolyte. The electrolyte is filled in each cell. The electrolyte may include, for example, a lithium salt and a solvent.

[0039] As shown in FIG. 2, the power generating element 50 may further include a terminal unit in addition to the electrode body 10. The terminal unit is disposed at an end in the stacking direction (the direction perpendicular to the surface). The terminal unit may have, for example, a monopolar structure. The terminal unit may be composed of, for example, a positive electrode layer 11 and a current collecting laminate 13 (first metal foil 13a). The terminal unit may be composed of, for example, a negative electrode layer 12 and a current collecting laminate 13 (second metal foil 13b).

[0040] The bipolar battery 100 shown in this embodiment can be used in a manufacturing method for producing recycled materials from the battery. The first metal foil 13a and the second metal foil 13b can be easily separated from the current collector laminate 13, making the battery suitable as a starting body for producing recycled materials. The bipolar battery 100 shown in this embodiment can be used in a disassembly method for batteries. The first metal foil 13a and the second metal foil 13b can be easily separated from the current collector laminate 13, making the battery efficient for disassembly. The bipolar battery 100 shown in this embodiment can be used in a recovery method for recovering materials from the battery. The first metal foil 13a and the second metal foil 13b can be easily separated from the current collector laminate 13, making the battery suitable as a starting body for use in a material recovery method. [Explanation of symbols]

[0041] 10 electrode body, 11 positive electrode layer, 12 negative electrode layer, 13 current collector laminate, 13a first metal foil, 13b second metal foil, 13c adhesive layer, 13d carbon coating layer, 14 missing portion, 20 separator, 30 sealing material, 50 power generating element, 90 exterior body, 91 first current collector plate, 92 first laminate film, 93 second laminate film, 94 second current collector plate, 100 bipolar battery.

Claims

1. a current collecting laminate and a sealing material that seals the current collecting laminate, the current collecting laminate has a first metal foil, an adhesive layer, and a second metal foil in this order; the adhesive layer has a defect portion extending inward from an end surface in an in-plane direction of the current collecting laminate, the sealing material is provided so as to cover the end face of the current collecting stack and to continuously cover a portion of an upper surface and a portion of a lower surface of the current collecting stack, The sealing material covers at least an in-plane area of ​​the upper surface and the lower surface corresponding to the missing portion.

2. The recess extends in an in-plane direction from the end surface by a length of less than 5 mm, The electrode body according to claim 1 , wherein the sealing material extends in an in-plane direction on the upper surface and the lower surface for a length of 5 mm or more from the end surface.

3. Further comprising a positive electrode layer and a negative electrode layer, 2. The electrode body according to claim 1, wherein the positive electrode layer, the first metal foil, the adhesive layer, the second metal foil, and the negative electrode layer are stacked in this order in an in-plane region where the sealing material is not provided.

4. The electrode assembly according to claim 3 , wherein the first metal foil comprises aluminum and the second metal foil comprises copper.

5. The electrode assembly according to claim 3 or 4 and a separator, A bipolar battery in which the electrode assemblies and the separators are alternately stacked.

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