Method for manufacturing recycled material and method for disassembling bipolar battery

Abstract

To provide a method capable of efficiently disassembling a bipolar battery and efficiently manufacturing a recycled material.SOLUTION: A manufacturing method for manufacturing a recycled material from a bipolar battery, wherein a current collector laminate in the bipolar battery has a coating layer containing an alkali-soluble resin in at least a part of a region in contact with the sealing material on the upper surface and the lower surface, the manufacturing method comprising, in order, (a) a step of preparing the bipolar battery, (b) a step of injecting an alkaline liquid into the cell through the liquid injection port to bring at least a part of the coating layer into contact with the alkaline liquid, and (c) a step of pulling out the sealing material from the bipolar battery.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing recycled materials and a method for dismantling bipolar batteries. [Background technology]

[0002] Japanese Patent Application Laid-Open No. 2007-180063 discloses a method for disassembling a solar cell module, which includes a heating step for thermally decomposing a buffer material and a swelling step for swelling a sealing material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-180063 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for recycling by recovering various materials from disused bipolar batteries, i.e., for producing recycled materials. Prior to producing recycled materials, it is expected that bipolar batteries can be efficiently disassembled.

[0005] An object of the present disclosure is to provide a method by which bipolar batteries can be efficiently dismantled and recycled materials can be efficiently produced. [Means for solving the problem]

[0006] 1. One aspect of the present disclosure is a method for producing recycled materials from a bipolar battery, the bipolar battery including a plurality of bipolar electrodes, a plurality of separators, and a sealing material, the plurality of bipolar electrodes and the plurality of separators being alternately stacked in a direction perpendicular to the surface, each of the plurality of bipolar electrodes including a positive electrode layer, a current collecting laminate, and a negative electrode layer in this order in the direction perpendicular to the surface, the sealing material continuously covering an end face in an in-plane direction of the current collecting laminate, a portion of an upper surface in the direction perpendicular to the surface, and a portion of a lower surface in the direction perpendicular to the surface, and filling spaces between adjacent bipolar electrodes to form a plurality of cells, each of the plurality of cells including the positive electrode layer, the separator, and the negative electrode layer stacked in the direction perpendicular to the surface, and an electrolyte injection port, the current collecting laminate having a coating layer containing an alkali-soluble resin on at least a portion of an area of ​​the upper surface and the lower surface that contacts the sealing material, the manufacturing method comprising: (a) providing the bipolar battery; (b) injecting an alkaline liquid into the cell through the inlet to bring at least a portion of the coating layer into contact with the alkaline liquid; and (c) removing the sealing material from the bipolar battery.

[0007] In the manufacturing method of the present disclosure, in step (b), the alkaline liquid is injected to bring at least a portion of the coating layer into contact with the alkaline liquid, thereby dissolving at least a portion of the coating layer and reducing the adhesive strength between the current collecting laminate and the sealing material. Therefore, step (c) can be carried out efficiently. Furthermore, in step (b), the injection port used for injecting the alkaline liquid is the same injection port formed for injecting the electrolyte, so there is no need to adjust the configuration of the bipolar battery just to carry out step (b).

[0008] 2. The manufacturing method described in the above item "1" may include, between the step (b) and the step (c), a step (d) of heating the coating layer.

[0009] 3. The manufacturing method described in the above item "1" or "2" may include, before the step (c), a step (e) of forming a cut in the sealing material.

[0010] 4. In the manufacturing method according to any one of the above items "1" to "3," the coating layer in the bipolar battery may further contain a carbon material.

[0011] 5. Another aspect of the present disclosure is a method for disassembling a bipolar battery, the bipolar battery including a plurality of bipolar electrodes, a plurality of separators, and a sealing material, the plurality of bipolar electrodes and the plurality of separators being alternately stacked in a direction perpendicular to the surface, each of the plurality of bipolar electrodes including a positive electrode layer, a current collecting laminate, and a negative electrode layer in this order in the direction perpendicular to the surface, the sealing material continuously covering an end face in an in-plane direction of the current collecting laminate, a portion of an upper surface in the direction perpendicular to the surface, and a portion of a lower surface in the direction perpendicular to the surface, and filling spaces between adjacent bipolar electrodes to form a plurality of cells, each of the plurality of cells including the positive electrode layer, the separator, and the negative electrode layer stacked in the direction perpendicular to the surface, and an electrolyte injection port, the current collecting laminate having a coating layer containing an alkali-soluble resin on at least a portion of an area of ​​the upper surface and the lower surface that contacts the sealing material, the disassembly method comprising: (a) providing the bipolar battery; (b) injecting an alkaline liquid into the cell through the inlet to bring at least a portion of the coating layer into contact with the alkaline liquid; and (c) pulling out the sealing material from the bipolar battery.

[0012] 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]

[0013] [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 taken along line III-III in FIG. [Figure 4] 3 is a schematic cross-sectional view showing a bipolar electrode and a first sealing material in the present embodiment. FIG. [Figure 5] FIG. 1 is a diagram showing a schematic flowchart of a method for producing recycled materials in this embodiment. [Figure 6] FIG. 1 is a cross-sectional view schematically showing an example of a method for injecting an alkaline liquid. DETAILED DESCRIPTION OF THE INVENTION

[0014] -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.

[0015] The "perpendicular to the surface" refers to the normal direction to the surface of a sheet-like member (e.g., foil, bipolar electrode, 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.

[0016] -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, and Fig. 3 is a schematic cross-sectional view taken along line III-III in Fig. 1.

[0017] The bipolar battery 100 includes multiple bipolar electrodes 10, multiple separators 20, and a first sealant 31. The bipolar battery 100 may further include a separator 20, a second sealant 32, and the like. The bipolar battery 100 includes an electrolyte (not shown). The multiple bipolar electrodes 10 and the multiple separators are alternately stacked in the perpendicular direction (Z-axis direction). Hereinafter, the perpendicular direction (Z-axis direction) will also be referred to as the "stacking direction." In the perpendicular direction, each of the multiple bipolar electrodes 10 includes a positive electrode layer 11, a current collecting laminate 13, and a negative electrode layer 12, in this order.

[0018] The current collecting laminate 13 is a conductor and may include, for example, a metal foil.

[0019] The positive electrode layer 11 is attached to the current collector laminate 13. 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, for example, a conductive material, a binder, and the like.

[0020] The negative electrode layer 12 is attached to the current collector laminate 13. In the current collector laminate 13, the negative electrode layer 12 is located on the opposite side of the positive electrode layer 11. The negative electrode layer 12 may have 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 material, a lithium-titanium composite oxide, or the like. The negative electrode layer 12 may also further include, for example, a conductive material, a binder, or the like.

[0021] The separator 20 is interposed between the bipolar electrodes 10. The separator 20 electrically separates the positive electrode layer 11 and the negative electrode layer 12 that are adjacent in the direction perpendicular to the surface. The separator 20 may include, for example, a porous resin membrane.

[0022] At the peripheral edges in the in-plane direction, the first sealant 31 fills the gaps between the bipolar electrodes 10 (the current collecting laminates 13). That is, at least a portion of the first sealant 31 fills the gaps between adjacent bipolar electrodes 10. This forms a plurality of cells 50. The first sealant 31 may contain, for example, polyolefin resin, epoxy resin, acrylic resin, fluororesin, etc.

[0023] A cell 50 is the smallest unit of a battery. Because the bipolar battery 100 includes multiple cells 50, it may also be called a "bipolar module." Each of the multiple cells 50 is sealed. That is, the bipolar battery 100 is sealed. The multiple cells 50 are isolated from each other. Each of the multiple cells 50 includes a positive electrode layer 11, a separator 20, a negative electrode layer 12, and an electrolyte. That is, each of the multiple cells 50 is filled with the electrolyte. The electrolyte is a liquid electrolyte. The electrolyte may include, for example, an organic solvent and a supporting salt (lithium salt), etc.

[0024] A liquid inlet 51 is formed in each of the multiple cells 50. For example, the liquid inlet 51 (through-hole) may be formed in the first sealant 31. When manufacturing the bipolar battery 100, the electrolyte is injected into the cell 50 through the liquid inlet 51. After the electrolyte is injected, the liquid inlet 51 may be closed by the second sealant 32. For example, the second sealant 32 may be heat-sealed to the first sealant 31. The second sealant 32 may be in the form of a film, for example. The second sealant 32 may include a metal foil laminate film, for example. The second sealant 32 may include an aluminum laminate film, for example. In addition to the liquid inlet 51, each of the multiple cells 50 may further be provided with, for example, a gas release valve.

[0025] The bipolar battery 100 may further include an exterior body (not shown). For example, the plurality of bipolar electrodes 10, the first seal material 31, and the second seal material 32 may all be packaged in the exterior body. The exterior body may include, for example, a metal foil laminate film.

[0026] FIG. 4 is a schematic cross-sectional view showing a bipolar electrode and a first sealing material according to this embodiment. As shown in FIG. 4, the current collecting laminate 13 may include, for example, a first metal foil 13a, an adhesive layer 13c, and a second metal foil 13b, arranged in this order in the perpendicular direction. The first metal foil 13a is a positive electrode current collecting foil. The first metal foil 13a may include, for example, aluminum (Al). The second metal foil 13b is a negative electrode current collecting foil. The second metal foil 13b may include, for example, copper (Cu). The first sealing material 31 continuously covers the in-plane end face 13e of the current collecting laminate 13, a portion of the perpendicular upper face 13f, and a portion of the perpendicular lower face 13g. The current collecting laminate 13 has a coating layer 13d containing an alkali-soluble resin. The coating layer 13d may cover the entire upper surface 13f and the lower surface 13g of the current collecting laminate 13, or may include the entire area in contact with the first seal material 31. The coating layer 13d includes at least a part of the area in contact with the first seal material 31.

[0027] The coating layer 13d contains an alkali-soluble resin and a carbon material. The alkali-soluble resin functions as a binder. Examples of alkali-soluble resins include (meth)acrylic resins (hereinafter also referred to as "acrylic resins"), phenolic resins, alkali-soluble polyimides, polymethyl glutarimide (PMGI), and polyhydroxystyrene. The alkali-soluble resin preferably contains an acrylic resin. The acrylic resin is a resin containing an acrylic monomer as a constituent unit. The acrylic resin may also contain a polymerizable monomer other than the acrylic monomer as a constituent unit. The acrylic resin contains an acrylic monomer as a constituent unit in an amount of preferably 30% by weight or more, more preferably 50% by weight or more, even more preferably 70% by weight or more, and even more preferably 90% by weight or more.

[0028] 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 coating layer 13d may further include, for example, another binder in addition to the alkali-soluble resin and the carbon material. Examples of other binders include polyvinylidene fluoride (PVDF). For example, the coating layer 13d may include a mass fraction of 10 to 90% of the carbon material, with the remainder being a binder. The binder preferably includes 50 mass% or more of an acrylic resin. The coating layer 13d may be formed, for example, by gravure coating.

[0029] The first sealant 31 may contain, for example, at least one selected from the group consisting of polyolefin resin, polyamide resin, acrylic resin, and fluororesin. The first sealant 31 may contain, for example, at least one selected from the group consisting of polyethylene (PE) and polypropylene (PP).

[0030] -Method of manufacturing recycled materials- FIG. 5 is a schematic flowchart of a method for producing recycled materials according to this embodiment. Hereinafter, the "method for producing recycled materials according to this embodiment" may be abbreviated as "this method." This method includes the steps of "(a) preparing a battery," "(b) injecting an alkaline liquid," and "(c) removing the first sealing material," in that order. This method may include, for example, "(d) heating the coating layer" between steps (b) and (c), or "(e) forming an incision in the first sealing material" before step (c). This method may further include "(f) dismantling the battery," "(g) recovering materials," and "(h) recycling materials," etc.

[0031] (a) Battery preparation This method includes preparing a bipolar battery 100. An example of the details of the bipolar battery 100 has been described above. That is, the bipolar battery 100 may be a battery to be subjected to this method. For example, a used battery that has progressed in deterioration may be prepared. For example, a defective battery discarded during a manufacturing process may be prepared. The bipolar battery 100 prepared in this process may be a sealed battery containing an electrolyte, or may be one that has not been filled with electrolyte or one from which the electrolyte has been exhausted.

[0032] (b) Injection of alkaline liquid In this method, alkaline liquid is injected into the cells through the inlet 51 of the bipolar battery 100. If the inlet 51 is electrically connected to the outside, the alkaline liquid is injected directly. If the bipolar battery 100 contains an electrolyte and is sealed, and the inlet 51 is not electrically connected to the outside, the inlet 51 of each cell is electrically connected to the outside. For example, as shown in FIG. 2, the bipolar battery 100 may include a first end E1 and a second end E2 in one direction perpendicular to the plane direction (e.g., the Y-axis direction). The second end E2 is located on the opposite side of the first end E1. For example, a conductive port may be formed in the first end E1 to connect the inlet 51 to the outside.

[0033] The inlet openings may be formed by any method. For example, the inlet openings may be formed by drilling holes in the film-like second sealing material 32 at positions corresponding to the injection openings 51. For example, by using a tool with multiple needle-shaped portions, such as a drilling jig, the inlet openings can be easily and simultaneously formed for each of the multiple cells 50. If electrolyte remains in the cells, the bipolar battery 100 may be heated to vaporize the electrolyte and drain it through the inlet openings. It is preferable to drain the electrolyte before injecting the alkaline liquid.

[0034] FIG. 6 is a cross-sectional view schematically illustrating an example of a method for injecting an alkaline liquid. As shown in FIG. 6, the alkaline liquid can be injected into the cell through an injection port 51. The alkaline liquid is injected to bring at least a portion of the coating layer 13d into contact with the alkaline liquid. In this method, the injection of the alkaline liquid brings at least a portion of the coating layer 13d into contact with the alkaline liquid, thereby dissolving at least a portion of the coating layer 13d and reducing the adhesive strength with the first sealant 31. This allows for efficient implementation of step (c). Furthermore, since the injection port used for injecting the alkaline liquid in step (b) is the injection port 51 formed for injecting the electrolyte, there is no need to adjust the configuration of the bipolar battery just to perform step (b).

[0035] The alkaline liquid used in step (b) may be an aqueous solution containing an alkali. Examples of the alkali include sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, ammonia, ethylamine, n-propylamine, diethylamine, di-n-propylamine, triethylamine, methyldiethylamine, dimethylethanolamine, triethanolamine, tetramethylammonium hydroxide, tetraethylammonium hydroxide, pyrrole, piperidine, 1,8-diazabicyclo[5,4,0]-7-undecene, and 1,5-diazabicyclo[4,3,0]-5-nonane. The aqueous solution containing an alkali may also contain a water-soluble organic solvent, a surfactant, or the like. Examples of the water-soluble organic solvent include methanol and ethanol.

[0036] To promote dissolution of the coating layer 13d by the alkaline liquid, for example, a step (step (d)) of heating the coating layer 13d may be included. Examples of a method for heating the coating layer 13d include heating the entire bipolar battery 100.

[0037] (c) Removal of the first seal material In this method, the first seal material 31 is pulled out from the bipolar battery 100. The adhesive strength between the first seal material 31 and the current collecting laminate 13 is reduced by step (b), making it easier to separate the first seal material 31 and the current collecting laminate 13. When the first seal material 31 is formed as an integral part, for example, as shown in FIG. 1 , incisions 14 may be made in the first seal material 31 (step (e)). The first seal material 31 can be divided at the incisions 14 and pulled out from the bipolar battery 100. The timing of making the incisions 14 in the first seal material 31 is not limited as long as it is made before step (c), and it may be made after step (b) or before step (b).

[0038] (f) Dismantling of batteries This method may include, for example, disassembling the bipolar battery 100 after the first sealing material 31 has been removed. Since the first sealing material 31 has been removed, it is expected that the other components can be easily disassembled. Therefore, for example, it is expected that the work efficiency during disassembly will be improved. After disassembly, various materials and components can be recovered from within the battery (step (g)). For example, the positive electrode active material, current collector foil, etc. may be recovered. In other words, this method may be used as a method for disassembling a bipolar battery.

[0039] (h) Regeneration This method may include, for example, producing recycled materials from recovered materials. For example, recovered materials or components may be used as recycled materials as they are (direct recycling). Various recycled materials may be produced by processing recovered materials or components. For example, a positive electrode active material may be regenerated from metal components extracted from the positive electrode active material. [Explanation of symbols]

[0040] 10 bipolar electrode, 11 positive electrode layer, 12 negative electrode layer, 13 current collector laminate, 13a first metal foil, 13b second metal foil, 13c adhesive layer, 13d coating layer, 14 notch, 20 separator, 31 first sealing material, 32 second sealing material, 50 cell, 51 filling port, 100 bipolar battery, E1 first end, E2 second end.

Claims

1. A manufacturing method for producing recycled materials from bipolar batteries, comprising: The bipolar battery includes a plurality of bipolar electrodes, a plurality of separators, and a sealant; the plurality of bipolar electrodes and the plurality of separators are alternately stacked in a direction perpendicular to the surface, each of the plurality of bipolar electrodes includes a positive electrode layer, a current collecting laminate, and a negative electrode layer in this order in the perpendicular direction; the sealing material continuously covers an end surface in an in-plane direction of the current collecting laminate, a part of an upper surface in a direction perpendicular to the plane, and a part of a lower surface in the direction perpendicular to the plane, and fills spaces between adjacent bipolar electrodes, thereby forming a plurality of cells; each of the plurality of cells includes the positive electrode layer, the separator, and the negative electrode layer stacked in a plane perpendicular direction, and an electrolyte injection port; the current collecting laminate has a coating layer containing an alkali-soluble resin on at least a part of the area of ​​the upper surface and the lower surface that contacts the sealing material, The manufacturing method includes: (a) providing the bipolar battery; (b) injecting an alkaline liquid into the cell through the inlet to bring at least a portion of the coating layer into contact with the alkaline liquid; and (c) removing the sealing material from the bipolar battery.

2. Between the step (b) and the step (c), The method of claim 1 , further comprising the step of: (d) heating the coating layer.

3. Before the step (c), The manufacturing method according to claim 1 or 2, further comprising: (e) forming a cut in the sealing material.

4. The manufacturing method according to claim 1 or 2, wherein the coating layer further contains a carbon material.

5. A method for dismantling a bipolar battery, comprising: The bipolar battery includes a plurality of bipolar electrodes, a plurality of separators, and a sealant; the plurality of bipolar electrodes and the plurality of separators are alternately stacked in a direction perpendicular to the surface, each of the plurality of bipolar electrodes includes a positive electrode layer, a current collecting laminate, and a negative electrode layer in this order in the perpendicular direction; the sealing material continuously covers an end surface in an in-plane direction of the current collecting laminate, a part of an upper surface in a direction perpendicular to the plane, and a part of a lower surface in the direction perpendicular to the plane, and fills spaces between adjacent bipolar electrodes, thereby forming a plurality of cells; each of the plurality of cells includes the positive electrode layer, the separator, and the negative electrode layer stacked in a plane perpendicular direction, and an electrolyte injection port; the current collecting laminate has a coating layer containing an alkali-soluble resin on at least a part of the area of ​​the upper surface and the lower surface that contacts the sealing material, The disassembly method includes: (a) providing the bipolar battery; (b) injecting an alkaline liquid into the cell through the inlet to bring at least a portion of the coating layer into contact with the alkaline liquid; and (c) pulling out the sealing material from the bipolar battery.

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