Method for producing recycled material and bipolar battery

Abstract

To provide a method for recovering an electrolyte from a bipolar battery.SOLUTION: The method for producing a recycled material includes the following (a) to (d). (a) preparing a sealed bipolar battery containing an electrolytic solution; (b) An exhaust port is formed in the bipolar battery. (c) heating the bipolar battery by induction heating to vaporize at least a portion of the electrolyte solution. (d) The vaporized electrolytic solution is collected from the exhaust port.SELECTED DRAWING: Figure 8

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open No. 2012-204000 discloses that a battery pack is heated to recover thermal decomposition products released from the battery pack. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-204000 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a demand for dismantling batteries that are no longer needed in order to recover various materials from the batteries and recycle them. It is expected that the efficiency of dismantling batteries will be improved if the electrolyte solution is recovered from the batteries prior to dismantling. Conventionally, it has been proposed to heat the batteries from the outside by bringing heated steam (heat medium) into contact with the batteries, and recover the vaporized electrolyte solution.

[0005] A bipolar battery is composed of multiple bipolar electrodes stacked on top of each other. A structure in which each bipolar electrode is sealed to separate it into multiple cells is being considered. When a bipolar battery with this structure is heated by contact with a heat transfer medium, heat conduction between the partitioned cells is difficult, which may result in low heating efficiency. In particular, the closer to the center of the stacking direction, the lower the heating efficiency, making it difficult to recover the electrolyte.

[0006] An object of the present disclosure is to provide a method for recovering electrolyte from a bipolar battery. [Means for solving the problem]

[0007] 1. One aspect of the present disclosure is a method for producing recycled materials. The method for producing recycled materials includes the following steps (a) to (d): (a) A sealed bipolar battery containing an electrolyte is provided. (b) Forming a vent in the bipolar battery. (c) heating the bipolar battery by induction heating to vaporize at least a portion of the electrolyte; (d) The vaporized electrolyte is collected from the exhaust port. The bipolar battery includes a plurality of bipolar electrodes and a sealing material. The bipolar electrodes are stacked in a direction perpendicular to the surface. Each of the bipolar electrodes includes a positive electrode layer, a current collecting foil, and a negative electrode layer in this order in the direction perpendicular to the surface. At least a portion of the sealing material fills the spaces between adjacent bipolar electrodes, thereby forming a plurality of cells. The cells are isolated from one another. The cells include a positive electrode layer, a negative electrode layer, and an electrolyte. In the above (b), an exhaust port is formed in each of the plurality of cells.

[0008] In the present disclosure, an exhaust port (gas outlet) is formed in each of the multiple cells. That is, an electrolyte recovery route is formed for each cell. Furthermore, in the present disclosure, the bipolar battery is heated by induction heating (IH). With IH, each of the multiple bipolar electrodes (current collector foils) within the battery can generate heat. That is, each of the multiple cells can be heated from the inside. The cell in the center of the stacking direction can also be sufficiently heated. Therefore, it is believed that the electrolyte can be recovered from each of the multiple cells.

[0009] 2. The method for producing recycled materials described in "1" above may include, for example, the following configuration: (c) above includes performing induction heating while applying pressure to the bipolar battery in a direction perpendicular to its surface.

[0010] Vaporization of the electrolyte can increase the internal pressure of the cell. This increase in internal pressure causes the cell to expand. When the cell expands, heating efficiency may decrease. Multiple cells are stacked in the perpendicular direction (stacking direction). Pressurizing the bipolar battery in the perpendicular direction can pressurize each of the multiple cells. Suppressing the expansion of each cell improves heating efficiency, which is expected to shorten the time required for evaporation of the electrolyte.

[0011] 3. The method for producing recycled materials described in "1" above may include, for example, the following configuration: (c) above includes moving a heating coil along the outer surface of the bipolar battery. In a direction perpendicular to the perpendicular direction, the bipolar battery includes a first end and a second end. The second end is located opposite the first end. An exhaust port is formed in the first end. The heating coil starts from the first end and moves toward the second end. A groove is formed in at least one of the positive electrode layer and the negative electrode layer. The groove extends along the direction of movement of the heating coil.

[0012] For example, if the entire bipolar battery is heated at once, the electrolyte vaporizes from the entire cell in the in-plane direction, and the vaporized electrolyte flows toward the exhaust port (exit) all at once. This can result in congestion of the electrolyte (gas), potentially reducing the efficiency of gas discharge from the exhaust port. IH is implemented using a heating coil. By sequentially heating the bipolar battery from the exhaust port side, the electrolyte (gas) vaporizes sequentially while ensuring a migration route for the electrolyte (gas). This is expected to ensure smooth migration of the electrolyte (gas). Furthermore, by forming grooves in the electrode layer along the migration route of the heating coil, the electrolyte (gas) is expected to migrate through the grooves. This can further improve the discharge efficiency.

[0013] 4. One aspect of the present disclosure is a bipolar battery. The bipolar battery includes multiple bipolar electrodes, a sealing material, and an electrolyte. The multiple bipolar electrodes are stacked in a direction perpendicular to the surface. Each of the multiple bipolar electrodes includes a positive electrode layer, a current collecting foil, and a negative electrode layer, in this order, in the direction perpendicular to the surface. At least a portion of the sealing material fills the gap between adjacent bipolar electrodes, thereby forming multiple cells. The multiple cells are isolated from each other. Each cell includes a positive electrode layer, a negative electrode layer, and an electrolyte. The multiple bipolar electrodes include a first bipolar electrode and a second bipolar electrode. The current collecting foil of the first bipolar electrode is thicker than the current collecting foil of the second bipolar electrode. In the direction perpendicular to the surface, the first bipolar electrode is located closer to the center than the second bipolar electrode.

[0014] In induction heating, individual cells are thought to be heated primarily by heat generated by the current collecting foil (conductor). For example, as the capacity of bipolar batteries increases, their thickness is also expected to increase. In thick bipolar batteries, the skin effect can cause a temperature difference between the current collecting foils located on the outer side of the stacking direction (perpendicular to the surface) and those located in the center. This temperature difference can reduce the efficiency of electrolyte drainage. Placing a thick current collecting foil in the center of the stacking direction is expected to increase eddy currents in the center of the stacking direction, resulting in an increase in the amount of heat generated. This is expected to reduce the temperature difference between the current collecting foils located on the outer side of the stacking direction and those located in the center. This reduction in temperature difference is expected to improve the efficiency of electrolyte drainage.

[0015] 5. The bipolar battery described in "4" above may include, for example, the following configuration: Each of the plurality of cells is provided with a liquid filling port. The sealing material includes a first sealing material and a second sealing material. The first sealing material fills the gap between adjacent bipolar electrodes. The second sealing material closes the liquid filling port. The second sealing material is in the form of a film.

[0016] For example, the liquid inlet can be easily opened by piercing the film-like second sealing material with a needle-shaped tool, etc. The opened liquid inlet can be used as an exhaust port when recovering the electrolyte.

[0017] 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]

[0018] [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] FIG. 2 is a schematic cross-sectional view taken along line IV-IV in FIG. [Figure 5] FIG. 2 is a schematic cross-sectional view showing an example of a laminated structure in the present embodiment. [Figure 6] FIG. 2 is a schematic plan view showing an example of a bipolar electrode in the present embodiment. [Figure 7] 1 is a schematic flowchart of a method for producing recycled materials in the present embodiment. [Figure 8] FIG. 2 is a schematic cross-sectional view showing an example of a drilling jig in the present embodiment. [Figure 9] FIG. 2 is a first schematic view showing an example of a heating jig in the present embodiment. [Figure 10] FIG. 2 is a second schematic view showing an example of a heating jig in the present embodiment. [Figure 11] FIG. 2 is a schematic cross-sectional view showing an example of a recovery jig in the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0019] -Terms and phrases- The terms "comprise," "include," "have," and variations thereof are open-ended. An open-ended configuration may or may not include additional elements in addition to the required elements.

[0020] Unless otherwise specified, the order of execution of multiple steps, actions, operations, etc. included in various methods is not limited to the order described. For example, multiple steps may proceed simultaneously. For example, multiple steps may occur one after the other.

[0021] 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.

[0022] The "perpendicular to the surface" refers to the normal direction to the surface of a sheet-like member (e.g., foil, 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.

[0023] -Bipolar battery- The bipolar battery may have any configuration as long as it has a bipolar structure and contains an electrolyte. In some embodiments, the bipolar battery may be a lithium-ion battery. In some embodiments, the bipolar battery may be a nickel-metal hydride battery. The following describes this embodiment of a lithium-ion battery as an example.

[0024] 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. Fig. 3 is a schematic cross-sectional view taken along line III-III in Fig. 1. Fig. 4 is a schematic cross-sectional view taken along line IV-IV in Fig. 1.

[0025] The bipolar battery 100 includes multiple bipolar electrodes 10, a first sealant 31, and an electrolyte (not shown). The bipolar battery 100 may further include a separator 20, a second sealant 32, and the like. The multiple bipolar electrodes 10 are 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 foil 13, and a negative electrode layer 12, in this order.

[0026] The current collector foil 13 is a conductor. The current collector foil 13 may include, for example, a metal foil. For example, the current collector foil 13 may be formed by bonding an aluminum (Al) foil and a copper (Cu) foil together.

[0027] The positive electrode layer 11 is attached to the current collector foil 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.

[0028] The negative electrode layer 12 is attached to the current collector foil 13. In the current collector foil 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, etc. The negative electrode layer 12 may also further include, for example, a conductive material, a binder, etc.

[0029] 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.

[0030] At the peripheral edges in the in-plane direction, the first sealing material 31 fills the spaces between the bipolar electrodes 10 (the current collecting foils 13). That is, at least a portion of the sealing material fills the spaces between adjacent bipolar electrodes 10. This forms a plurality of cells 50. The first sealing material 31 may contain, for example, polyolefin resin, epoxy resin, acrylic resin, fluororesin, etc.

[0031] 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.

[0032] A liquid inlet 51 may be 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, for example, in the form of a film. The second sealant 32 may include, for example, a metal foil laminate film or the like. The second sealant 32 may include, for example, an aluminum laminate film or the like. In addition to the liquid inlet 51, for example, a gas release valve or the like may be further provided in each of the multiple cells 50.

[0033] 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.

[0034] 5 is a schematic cross-sectional view showing an example of a stacked structure in this embodiment. In some of the present embodiments, the thickness of the current collecting foils 13 in the multiple bipolar electrodes 10 may be uniform. In some of the present embodiments, the thickness of the current collecting foils 13 in the multiple bipolar electrodes 10 may differ from one another. The difference in thickness of the current collecting foils 13 may improve the heating efficiency by induction heating.

[0035] For example, the multiple bipolar electrodes 10 may include a first bipolar electrode 10a and a second bipolar electrode 10b. The first current collecting foil 13a of the first bipolar electrode 10a is thicker than the second current collecting foil 13b of the second bipolar electrode 10b. In the perpendicular direction (stacking direction), the first bipolar electrode 10a is located closer to the center than the second bipolar electrode 10b. For example, the first bipolar electrode 10a may be located in the center in the stacking direction. For example, the second bipolar electrode 10b may be located at both ends in the stacking direction. The ratio of the thickness of the first current collecting foil 13a to the thickness of the second current collecting foil 13b may be, for example, 1.01 or more, 1.05 or more, 1.1 or more, or 1.2 or more. The ratio of the thickness of first current collector foil 13a to the thickness of second current collector foil 13b may be, for example, 2.0 or less, 1.5 or less, or 1.2 or less.

[0036] For example, the thickness of the current collector foil 13 may increase stepwise from both ends toward the center in the stacking direction (Z-axis direction). The ratio of the thickness of the current collector foils 13 between adjacent bipolar electrodes 10 may be, for example, 1.01 or more, 1.05 or more, 1.1 or more, or 1.2 or more. The ratio of the thickness of the current collector foils 13 between adjacent bipolar electrodes 10 may be, for example, 2.0 or less, 1.5 or less, or 1.2 or less. The thickness of the second current collector foil 13b (or the thinnest current collector foil 13) may be, for example, 5 μm or more, 10 μm or more, 25 μm or more, or 50 μm or more. The thickness of the second current collector foil 13b (or the thinnest current collector foil 13) may be, for example, 100 μm or less, 75 μm or less, or 50 μm or less.

[0037] FIG. 6 is a schematic plan view showing an example of a bipolar electrode according to this embodiment. A groove 14 may be formed in at least one of the positive electrode layer 11 and the negative electrode layer 12. In FIG. 6, as an example, the groove 14 is formed in the positive electrode layer 11. A similar groove 14 may also be formed in the negative electrode layer 12 (back surface). The groove 14 indicates a portion that is lower than the surface of the electrode layer. The current collecting foil 13 may be exposed at the bottom of the groove 14. The positive electrode layer 11 may be formed at the bottom of the groove 14. The groove 14 may extend linearly, for example. The groove 14 may extend along the inflow direction (Y-axis direction) of the electrolyte solution from the inlet 51. For example, the extension direction of the groove 14 may be parallel to the inflow direction of the electrolyte solution. The groove 14 can serve as a permeation path for the electrolyte solution. The groove 14 aligned along the inflow direction of the electrolyte solution is expected to promote permeation of the electrolyte solution during injection. A single groove 14 may be formed. There may be formed a plurality of grooves 14. The plurality of grooves 14 may be arranged in parallel lines (stripes).

[0038] -Method of manufacturing recycled materials- FIG. 7 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 "(a) preparing a battery," "(b) forming an exhaust port," "(c) induction heating," and "(d) recovering the electrolyte." This method may further include, for example, "(e) dismantling the battery," "(f) recovering materials," and "(g) regenerating materials."

[0039] (a) Battery preparation This method includes preparing a bipolar battery 100. Details of the bipolar battery 100 are as 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 deteriorated may be prepared. For example, a defective battery discarded during the manufacturing process may be prepared.

[0040] (b) Formation of exhaust vent The method includes forming an exhaust port in the bipolar battery 100. The exhaust port is formed in each of the plurality of cells 50. In each cell 50, the exhaust port may be formed at any position. For example, as shown in FIG. 2, the bipolar battery 100 may include a first end E1 and a second end E2 in a 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, the exhaust port may be formed in the first end E1.

[0041] The exhaust port can be formed by any method. Fig. 8 is a schematic cross-sectional view showing an example of a drilling jig in this embodiment. For example, when the cell 50 has a liquid injection port 51, the exhaust port may be formed by drilling a film-like second sealing material 32. For example, by using a jig having multiple needle-shaped portions 201, such as drilling jig 200, exhaust ports can be easily and simultaneously formed for each of the multiple cells 50.

[0042] If the cell 50 has a gas exhaust valve (not shown), the gas exhaust valve may be opened. However, the gas exhaust valve usually includes a metal member. Therefore, when opening the gas exhaust valve with a needle or the like, it is considered that opening the liquid injection port 51 is less likely to cause problems such as a short circuit than opening the gas exhaust valve.

[0043] (c) Induction heating This method includes heating the bipolar battery 100 by induction heating to vaporize at least a portion of the electrolyte. The entire electrolyte may be vaporized. A portion of the electrolyte may be vaporized. For example, only the organic solvent contained in the electrolyte may be vaporized. For example, the supporting salt may remain in the battery without being vaporized. As long as the bipolar battery 100 is heated by induction heating, any heating method may be used.

[0044] FIG. 9 is a first schematic diagram showing an example of a heating jig in this embodiment. The first heating jig 310 includes a restraint plate 311 and a first heating coil 312. The first heating coil 312 is a flat coil. When a high-frequency current is applied to the first heating coil 312, eddy currents can be generated in conductors (e.g., the current collector foil 13) within the battery. The first heating coil 312 is held by the restraint plate 311. The first heating coil 312 extends across the entire restraint plate 311 in the in-plane direction. The bipolar battery 100 is sandwiched between the pair of restraint plates 311. The pair of restraint plates 311 are configured to apply pressure to the bipolar battery 100 in the direction perpendicular to the surface (Z-axis direction). The first heating jig 310 makes it possible to heat the bipolar battery 100 while applying pressure to it. The pressure can suppress expansion of each cell 50. As a result, it is expected that the heating efficiency (i.e., the vaporization efficiency of the electrolyte) will be improved.

[0045] FIG. 10 is a second schematic diagram showing an example of a heating jig in this embodiment. The second heating jig 320 includes a second heating coil. The second heating coil is a ring-shaped air-core coil. The air-core portion 321 of the second heating coil may have a shape that follows the outer shape of the bipolar battery 100. When a high-frequency current is passed through the second heating coil, eddy currents may be generated locally within the battery. The bipolar battery 100 may be passed through the air-core portion 321. In other words, this method may include moving the heating coil along the outer surface of the bipolar battery 100. The second heating jig 320 allows the bipolar battery 100 to be locally heated and the heated area to be moved.

[0046] For example, the second heating jig 320 (heating coil) may move from the first end E1 where the exhaust port (pouring port 51) is formed toward the second end E2 on the opposite side. By sequentially heating from the exhaust port (gas outlet) side, the electrolyte can be sequentially vaporized while a gas exhaust route is secured. This is expected to improve gas exhaust efficiency.

[0047] Furthermore, as shown in FIG. 6, when grooves 14 are formed in at least one of the positive electrode layer 11 and the negative electrode layer 12, for example, the movement direction of the second heating jig 320 (heating coil) may be along the extension direction (Y-axis direction) of the grooves 14. The grooves 14 can also serve as a movement path for the gas (electrolyte). By moving the heating coil along the extension direction of the grooves 14, it is expected that the gas discharge efficiency will be further improved. For example, the movement direction of the heating coil may be parallel to the extension direction of the grooves 14.

[0048] (d) Recovery of electrolyte This method includes recovering the vaporized electrolyte solution from the exhaust port. Any recovery method may be used. FIG. 11 is a schematic cross-sectional view showing an example of a recovery tool in this embodiment. The recovery tool 400 (recovery joint) is configured to collectively cover multiple exhaust ports (liquid injection ports 51). The arrows in FIG. 11 indicate an example of a movement path of the electrolyte solution (gas). The recovery tool 400 makes it possible to efficiently recover gas from each of the multiple cells 50. The recovered gas may be liquefied by cooling. A recycled material may be produced from the recovered electrolyte solution (organic solvent). The recovered organic solvent may be reused.

[0049] (e) Dismantling of batteries This method may include, for example, disassembling the bipolar battery 100 after recovering the electrolyte. Because the disassembly is performed after recovering the electrolyte, it is expected that problems such as short circuits are less likely to occur during disassembly. Therefore, it is expected that the work efficiency during disassembly is improved.

[0050] (f) Recovery of materials This method may include recovering various materials and components from within the bipolar battery 100 after disassembling the battery. For example, the positive electrode active material, current collector foil, etc. may be recovered.

[0051] (g) Reclaiming materials 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]

[0052] 10 bipolar electrode, 10a first bipolar electrode, 10b second bipolar electrode, 11 positive electrode layer, 12 negative electrode layer, 13 current collecting foil, 13a first current collecting foil, 13b second current collecting foil, 14 groove, 20 separator, 31 first sealing material, 32 second sealing material, 50 cell, 51 filling port, 100 bipolar battery, 200 drilling jig, 201 needle-shaped portion, 310 first heating jig, 311 restraint plate, 312 first heating coil, 320 second heating jig, 321 air core portion, 400 recovery jig, E1 first end, E2 second end.

Claims

1. (a) providing a sealed bipolar battery containing an electrolyte; (b) forming a vent in the bipolar battery; (c) heating the bipolar battery by induction heating to vaporize at least a portion of the electrolyte; and (d) recovering the vaporized electrolyte from the exhaust port; Including, The bipolar battery includes a plurality of bipolar electrodes and a sealing material; The plurality of bipolar electrodes are stacked in a direction perpendicular to the surface, each of the plurality of bipolar electrodes includes a positive electrode layer, a current collecting foil, and a negative electrode layer in this order in the plane perpendicular direction; At least a portion of the sealing material fills the gaps between adjacent bipolar electrodes to form a plurality of cells, The plurality of cells are isolated from one another; The plurality of cells include the positive electrode layer, the negative electrode layer, and the electrolyte solution, and In the method (b), the exhaust port is formed in each of the plurality of cells. How recycled materials are produced.

2. The step (c) includes performing the induction heating while applying pressure to the bipolar battery in the direction perpendicular to the surface. A method for producing the recycled material according to claim 1.

3. (c) includes moving a heating coil along an outer surface of the bipolar battery; In a direction perpendicular to the plane-normal direction, the bipolar battery includes a first end and a second end, the second end is located opposite the first end, the exhaust port is formed in the first end, the heating coil starts at the first end and moves toward the second end; A groove is formed in at least one of the positive electrode layer and the negative electrode layer, and The groove extends along the direction of movement of the heating coil. A method for producing the recycled material according to claim 1.

4. a plurality of bipolar electrodes, a sealing material, and an electrolyte; The plurality of bipolar electrodes are stacked in a direction perpendicular to the surface, each of the plurality of bipolar electrodes includes a positive electrode layer, a current collecting foil, and a negative electrode layer in this order in the plane perpendicular direction; At least a portion of the sealing material fills the gaps between adjacent bipolar electrodes to form a plurality of cells, The plurality of cells are isolated from one another; the plurality of cells each including the positive electrode layer, the negative electrode layer, and the electrolyte; the plurality of bipolar electrodes include a first bipolar electrode and a second bipolar electrode; The current collecting foil of the first bipolar electrode is thicker than the current collecting foil of the second bipolar electrode, and In the direction perpendicular to the surface, the first bipolar electrode is located closer to the center than the second bipolar electrode. Bipolar battery.

5. Each of the plurality of cells is provided with a liquid inlet, the sealing material includes a first sealing material and a second sealing material; the first sealing material fills the gaps between the adjacent bipolar electrodes, the second sealing material closes the liquid injection hole, and The second sealing material is in a film form.

5. The bipolar battery according to claim 4.

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