Bipolar battery and method for manufacturing recycled material

Abstract

To provide a bipolar battery easy to be disassembled.SOLUTION: The bipolar battery includes a plurality of bipolar electrodes and a sealing material. The plurality of bipolar electrodes are stacked in the surface-perpendicular direction. In the through-plane direction, each of the plurality of bipolar electrodes includes a positive electrode layer, a collector foil, and a negative electrode layer in this order. In the in-plane direction, the current collector foil extends outward as compared with the positive electrode layer and the negative electrode layer. The seal material is joined to the current collector foil at the end in the in-plane direction, thereby sealing between the current collector foils adjacent to each other in the through-plane direction. The seal material includes a first resin layer and a second resin layer in the surface-perpendicular direction. The relationship "Tm2 <Tm1 <Tm0" is satisfied. "Tm0" indicates the melting points of the current collector foils. "Tm1" indicates the melting temperature of the first polymer layer. "Tm2" indicates the melting temperature of the second plastic layer.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Japanese Patent Application Laid-Open Publication No. 2010-277862 discloses a bipolar battery. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-277862 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 divided into multiple cells by sealing the spaces between each bipolar electrode are being considered. These bipolar batteries tend to have large sealed areas. When disassembling a bipolar battery, the challenge is how to separate the sealing material that firmly joins the bipolar electrodes (collector foils) together.

[0006] An object of the present disclosure is to provide a bipolar battery that is easy to disassemble. [Means for solving the problem]

[0007] 1. One aspect of the present disclosure is a bipolar battery. The bipolar battery includes a plurality of bipolar electrodes and a sealing material. The plurality of bipolar electrodes are stacked in the plane normal direction. In the plane normal direction, each of the plurality of bipolar electrodes includes a positive electrode layer, a current collector foil, and a negative electrode layer in this order. In the in-plane direction, the current collector foil extends outward compared to the positive electrode layer and the negative electrode layer. At the end in the in-plane direction, the sealing material is joined to the current collector foil, thereby sealing the space between the current collector foils adjacent in the plane normal direction. The sealing material includes a first resin layer and a second resin layer in the plane normal direction. The relationship of "Tm2 < Tm1 < Tm0" is satisfied. "Tm0" represents the melting point of the current collector foil. "Tm1" represents the melting point of the first resin layer. "Tm2" represents the melting point of the second resin layer.

[0008] In the present disclosure, the sealing material includes a first resin layer and a second resin layer. The second resin layer is so-called a release layer. Among the second resin layer, the first resin layer, and the current collector foil, the second resin layer has the lowest melting point. Therefore, by heating the sealing material at a temperature equal to or higher than the melting point of the second resin layer and lower than the melting point of the first resin layer, the second resin layer can be selectively melted. Starting from the vulnerable part generated by the melting of the second resin layer, the sealing material can be easily peeled off from the current collector foil. That is, a bipolar battery that is easy to disassemble can be provided.

[0009] 2. The bipolar battery described in "1" above may include, for example, the following configuration. The second resin layer is thinner than the first resin layer.

[0010] Since the second resin layer (release layer) is relatively thin, it is considered that heat is easily transmitted to the entire area of the second resin layer. Since the first resin layer is relatively thick, for example, an improvement in sealing performance is expected.

[0011] 3. The bipolar battery described in "1" or "2" above may include, for example, the following configuration. The second resin layer includes at least a part of the interface between the sealing material and the current collector foil.

[0012] By disposing the second resin layer at the interface between the sealing material and the current collecting foil, separation of the sealing material and the current collecting foil can be promoted.

[0013] 4. The bipolar battery according to any one of the above items "1" to "3" may include, for example, the following configuration: In the in-plane direction, the second resin layer extends along the periphery of the current collecting foil.

[0014] 5. The bipolar battery according to any one of the above items "1" to "4" may include, for example, the following configuration: In the perpendicular direction, the sealing material includes a second resin layer, a first resin layer, and a second resin layer in this order.

[0015] The sealing material may have a multi-layer structure, for example, three or more layers.

[0016] 6. The bipolar battery according to any one of the above items "1" to "5" may include, for example, the following configuration: The second resin layer covers the entire surface of the first resin layer.

[0017] 7. The bipolar battery according to any one of the above items "1" to "5" may include, for example, the following configuration: The second resin layer covers a part of the surface of the first resin layer.

[0018] 8. One aspect of the present disclosure is a method for producing recycled materials. The method for producing recycled materials includes the following (a) and (b): (a) Prepare a bipolar battery described in any one of the above items "1" to "7". (b) At least a portion of the second resin layer is selectively melted or dissolved to separate the bipolar electrodes.

[0019] As described above, the second resin layer may be selectively melted by heating the sealing material. For example, the second resin layer may be dissolved by applying a solvent that selectively dissolves the second resin layer to the sealing material.

[0020] 9. The method for producing recycled materials described in "8" above may include, for example, the following configuration: (b) above includes heating the sealing material at a temperature equal to or higher than Tm2 and lower than Tm1.

[0021] 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]

[0022] [Figure 1] 1 is a schematic top view of a bipolar battery according to an embodiment of the present invention. FIG. [Figure 2] FIG. 2 is a schematic cross-sectional view taken along line II-II in FIG. [Figure 3] 1 is a first schematic cross-sectional view showing an example of a sealing material according to the present embodiment. [Figure 4] FIG. 2 is a second schematic cross-sectional view showing an example of the sealing material in the present embodiment. [Figure 5] FIG. 3 is a third schematic cross-sectional view showing an example of the sealing material in the present embodiment. [Figure 6] 1 is a schematic flowchart showing a method for producing recycled materials in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] -Terms and phrases- "Comprises," "includes," "has," and variations thereof are open-ended expressions. An open-ended structure may or may not further include additional elements in addition to the required elements. "Consists of" is a closed expression. However, even a closed structure may include additional elements that are normally associated impurities or unrelated to the subject technology. "Consists essentially of..." is a semi-closed expression. A semi-closed structure allows the addition of elements that do not substantially affect the basic and novel characteristics of the subject technology.

[0024] 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.

[0025] The terms "first," "second," etc. are used only to distinguish between multiple elements. Such terms do not limit the elements to which they are attached. Such terms have no bearing on, for example, the order or importance of the elements to which they are attached.

[0026] 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.

[0027] 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.

[0028] The melting point "Tm0" of the current collector foil can be measured by a conventional melting point test. For example, if the current collector foil contains two or more types of metal foil (metal layer), the lower melting point is considered to be the melting point of the current collector foil. The melting points "Tm1" and "Tm2" of the resin material indicate the "melting temperature" measured in accordance with JIS K 7121.

[0029] "Selectively" means that under the same conditions, such as heating, the value of the second resin layer is greater than the value of the first resin layer and the value of the current collecting foil in at least one of the melting amount (per unit mass), melting rate, dissolution amount (per unit mass), and dissolution rate.

[0030] All numerical values ​​are modified by the term "about." The term "about" may mean, for example, ±5%, ±3%, ±1%, etc. All numerical values ​​may be approximate values ​​that may vary depending on the application of the subject technology. All numerical values ​​may be expressed with significant figures. Unless otherwise specified, measured values ​​may be average values ​​of multiple measurements. The number of measurements may be three or more, five or more, or ten or more. In general, the more measurements are made, the more reliable the average value is expected to be. Measured values ​​may be rounded to the nearest significant figure. Measured values ​​may include errors, such as those associated with the detection limits of the measuring device.

[0031] "Greater than or equal to" and "less than or equal to" are expressed by inequality signs with an equal sign "≦, ≧". "Greater than" and "less than" are expressed by inequality signs without an equal sign "<, >". Any numerical value selected from within a numerical range may be used as the new upper or lower limit.

[0032] -Bipolar battery- The bipolar battery may have any configuration. In some of the present embodiments, the bipolar battery may be a liquid lithium-ion battery. In some of the present embodiments, the bipolar battery may be an all-solid-state lithium-ion battery. In some of the present embodiments, the bipolar battery may be a nickel-metal hydride battery. The present embodiment relating to a liquid lithium-ion battery will be described below as an example.

[0033] FIG. 1 is a schematic top 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 multiple bipolar electrodes 10, a sealing material 30, and an electrolyte (not shown). The bipolar battery 100 may further include a separator 20. The multiple bipolar electrodes 10 are stacked in a direction perpendicular to the surface (Z-axis direction). The direction perpendicular to the surface (Z-axis direction) may also be referred to as the "stacking direction." In the direction perpendicular to the surface, 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.

[0034] 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 together an aluminum foil (melting point: 660°C) and a copper foil (melting point: 1085°C). In this case, the melting point "Tm0" of the current collector foil 13 is 660°C. In the in-plane direction, the current collector foil 13 extends outward compared to the positive electrode layer 11 and the negative electrode layer 12.

[0035] The positive electrode layer 11 is attached to one surface of 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.

[0036] The negative electrode layer 12 is attached to one surface of the current collector foil 13. In the current collector foil 13, the negative electrode layer 12 is located on the opposite surface to 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.

[0037] 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.

[0038] The sealing material 30 is joined to the current collector foil 13 at the end in the in-plane direction. For example, the sealing material 30 may be heat-welded to the current collector foil 13. For example, the sealing material 30 may be disposed around the entire periphery in the in-plane direction. By joining the sealing material 30 to the current collector foil 13, the spaces between adjacent current collector foils 13 in the direction perpendicular to the plane are sealed.

[0039] In the in-plane direction, the outside of the sealing material 30 may be further sealed by a second sealing material 40. The second sealing material 40 may contain, for example, polypropylene, polyphenylene sulfide, modified polyphenylene ether, or the like.

[0040] The spaces between the current collecting foils 13 are sealed to form a plurality of cells 50. The cell 50 is the smallest unit of a battery. The bipolar battery 100 includes a plurality of cells 50, and therefore may also be called a "bipolar module." The plurality of cells 50 are isolated from one another. Each of the plurality of cells 50 includes a positive electrode layer 11, a separator 20, a negative electrode layer 12, and an electrolyte solution. The electrolyte solution is a liquid electrolyte. The electrolyte solution may include, for example, an organic solvent and a supporting salt (lithium salt), etc.

[0041] The sealing material 30 includes a first resin layer 31 and a second resin layer 32 in the plane normal direction. The melting point "Tm2" of the second resin layer 32 is lower than the melting point "Tm1" of the first resin layer 31. As long as the relationship "Tm2 < Tm1 < Tm0" is satisfied, the first resin layer 31 and the second resin layer 32 can contain any resin material. For example, a resin material may be selected from the following material group so that the relationship "Tm2 < Tm1 < Tm0" is satisfied. The melting points listed together with each resin material are for reference. For example, the melting point may change due to molecular weight, density, acid modification, etc.

[0042] Low-density polyethylene (melting point: 100 °C), high-density polyethylene (melting point: 130 °C), polypropylene (melting point: 160 °C), polyacetal (melting point: 180 °C), nylon 6 (melting point: 225 °C), nylon 66 (melting point: 265 °C), polybutylene terephthalate (melting point: 224 °C), polyphenylene sulfide (melting point: 290 °C), polyether ether ketone (melting point: 343 °C)

[0043] In some embodiments, for example, low-density polyethylene can be selected as the second resin layer 32. In some embodiments, for example, high-density polyethylene can be selected as the first resin layer 31.

[0044] The difference in melting point "Tm1 - Tm2" may be, for example, 10 °C or more. The difference in melting point may be, for example, 25 °C or more, 50 °C or more, 75 °C or more, or 100 °C or more. The difference in melting point may be, for example, 200 °C or less, 150 °C or less, 100 °C or less, or 75 °C or less.

[0045] The second resin layer 32 may be thinner than the first resin layer 31. The ratio of the thickness of the second resin layer 32 to the thickness of the first resin layer 31 may be, for example, 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less. The ratio of the thickness of the second resin layer 32 to the thickness of the first resin layer 31 may be, for example, 0.01 or more, 0.05 or more, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, or 0.6 or more.

[0046] The thickness of the second resin layer 32 may be, for example, 1 μm or more, 10 μm or more, 25 μm or more, 50 μm or more, or 75 μm or more. The thickness of the second resin layer 32 may be, for example, 100 μm or less, 75 μm or less, or 50 μm or less.

[0047] The thickness of the first resin layer 31 may be, for example, more than 100 μm, 150 μm or more, 200 μm or more, 300 μm or more, 400 μm or more, 500 μm or more, 600 μm or more, 700 μm or more, 800 μm or more, or 900 μm or more. The thickness of the first resin layer 31 may be, for example, 1000 μm or less, 900 μm or less, 800 μm or less, 700 μm or less, 600 μm or less, or 500 μm or less.

[0048] FIG. 3 is a first schematic cross-sectional view showing an example of a sealing material in this embodiment. The second resin layer 32 may include, for example, a portion of the interface between the sealing material 30 and the current collecting foil 13. The second resin layer 32 may include, for example, the entire interface between the sealing material 30 and the current collecting foil 13. That is, the second resin layer 32 may include at least a portion of the interface between the sealing material 30 and the current collecting foil 13. The second resin layer 32 may cover a portion of the surface of the first resin layer 31. The second resin layer 32 may cover the entire surface of the first resin layer 31. An end face of the second resin layer 32 may be exposed to the outside in the in-plane direction (Y-axis direction). The second resin layer 32 may be exposed from the current collecting foil 13 in the in-plane direction. The second resin layer 32 may extend outward beyond the current collecting foil 13 in the in-plane direction.

[0049] In the in-plane direction (the direction normal to the paper surface), the second resin layer 32 may extend along the periphery of the current collector foil 13. The second resin layer 32 may be formed over the entire periphery of the current collector foil.

[0050] The second resin layer 32 may be formed on one side of the first resin layer 31. The second resin layer 32 may be formed on both sides of the first resin layer 31. That is, in the direction perpendicular to the surface, the sealing material 30 may include the second resin layer 32, the first resin layer 31, and the second resin layer 32 in this order.

[0051] 4 is a second schematic cross-sectional view showing an example of the sealing material according to the present embodiment. In the direction perpendicular to the surface, the sealing material 30 may include a first resin layer 31, a second resin layer 32, and another first resin layer 31 in this order.

[0052] FIG. 5 is a third schematic cross-sectional view showing an example of a sealing material according to this embodiment. The sealing material 30 may further include an additional layer in addition to the first resin layer 31 and the second resin layer 32. The sealing material 30 may further include, for example, a spacer layer 33. The spacer layer 33 may be disposed at the center of the sealing material 30 in the direction perpendicular to the surface. The first resin layer 31 may be bonded to the spacer layer 33. The spacer layer 33 may include, for example, ABS, polycarbonate, polyethylene terephthalate, polyethylene, polypropylene, polyimide, or the like. The spacer layer 33 may be thicker than the first resin layer 31. The thickness of the spacer layer 33 may be, for example, 0.1 to 3 mm.

[0053] -Method of manufacturing recycled materials- FIG. 6 is a schematic flowchart showing the method for producing recycled materials in this embodiment. Hereinafter, "the method for producing recycled materials in this embodiment" may be abbreviated as "the method." The method includes "(a) preparation" and "(b) separation." The method may further include, for example, "(c) recovery."

[0054] (a) Preparation This method includes preparing a bipolar battery 100. Details of the bipolar battery 100 are as described above. For example, a used battery that has progressed in degradation may be prepared. For example, a defective battery discarded during the manufacturing process may be prepared.

[0055] (b) Separation This method includes separating the bipolar electrodes 10 from each other by selectively melting or dissolving at least a portion of the second resin layer 32. For example, the second sealant 40 may be removed in advance by cutting or the like. A portion of the second resin layer 32 may be melted, or the entire second resin layer 32 may be melted. For example, this method may include heating the sealant 30 at a temperature equal to or higher than Tm2 and lower than Tm1. Any heating method may be used. For example, a heating iron or the like may be used. Note that a portion of the first resin layer 31 may be melted.

[0056] In some embodiments of the present invention, the first resin layer 31 and the second resin layer 32 have different solubility parameters. For example, a solvent that selectively dissolves the second resin layer 32 may be applied to the sealant 30. In some embodiments of the present invention, a solvent and heating may be used in combination.

[0057] (c) Recovery For example, the method may further include recovering various materials from the separated bipolar electrode 10. For example, the positive electrode composite (positive electrode layer 11), the negative electrode composite (negative electrode layer 12), the current collector foil 13, etc. may be recovered.

[0058] Recycled materials may be produced from the recovered materials. For example, various battery materials may be produced. For example, the recovered positive electrode active material may be used as the recycled material as is (direct recycling). For example, a positive electrode active material may be synthesized from the recovered material (metal salt). For example, various metal products may be produced by melting and refining the recovered current collecting foil. [Explanation of symbols]

[0059] 10 bipolar electrode, 11 positive electrode layer, 12 negative electrode layer, 13 current collecting foil, 20 separator, 30 sealing material, 31 first resin layer, 32 second resin layer, 33 spacer layer, 40 second sealing material, 50 cell, 100 bipolar battery.

Claims

1. 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; the current collecting foil extends outward relative to the positive electrode layer and the negative electrode layer in an in-plane direction, the sealing material is joined to the current collecting foil at the end portion in the in-plane direction, thereby sealing the spaces between the current collecting foils adjacent to each other in the perpendicular-to-plane direction; the sealing material includes a first resin layer and a second resin layer in the surface-perpendicular direction, Tm 2 <Tm 1 <Tm 0 The relationship is satisfied, The Tm 0 indicates the melting point of the current collecting foil, The Tm 1 indicates the melting point of the first resin layer, and The Tm 2 indicates the melting point of the second resin layer, Bipolar battery.

2. The second resin layer is thinner than the first resin layer.

10. The bipolar battery of claim 1.

3. the second resin layer includes at least a part of the interface between the sealing material and the current collecting foil; 10. The bipolar battery of claim 1.

4. In the in-plane direction, the second resin layer extends along the periphery of the current collecting foil.

10. The bipolar battery of claim 1.

5. In the plane perpendicular direction, the sealing material includes the second resin layer, the first resin layer, and the second resin layer in this order.

10. The bipolar battery of claim 1.

6. The second resin layer covers the entire surface of the first resin layer.

10. The bipolar battery of claim 1.

7. the second resin layer covers a portion of the surface of the first resin layer; 10. The bipolar battery of claim 1.

8. (a) providing a bipolar battery according to any one of claims 1 to 7; and (b) selectively melting or dissolving at least a portion of the second resin layer to separate the bipolar electrodes; Including, How recycled materials are produced.

9. (b) is the Tm 2 As mentioned above, the Tm 1 heating the sealant at a temperature less than A method for producing the recycled material according to claim 8.

Images