Bipolar electrode, bipolar battery, and method for manufacturing recycled material

Abstract

To provide a bipolar electrode which can be easily separated into a positive electrode and a negative electrode.SOLUTION: The bipolar electrode includes a positive electrode composite material layer, a positive electrode collector foil, an interposed film, a negative electrode collector foil, and a negative electrode composite material layer in this order in a direction perpendicular to a surface of the bipolar electrode. Each of the positive electrode collector foil and the negative electrode collector foil adheres to the intervening film. The positive electrode composite material layer is attached to the positive electrode collector foil. The negative electrode composite material layer is attached to the negative electrode collector foil. The intervening film has conductivity. At least one of the positive electrode collector foil and the negative electrode collector foil is configured to be separated from the intervening film before the intervening film breaks when the intervening film is stretched in the in-plane direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] JP 2022-114963 A discloses a method for recovering metal materials from bipolar electrodes. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-114963 Summary of the Invention [Problem to be solved by the invention]

[0004] There is a need to recover materials from discarded batteries for recycling. The positive and negative electrodes can be recovered separately from monopolar batteries. The positive and negative electrodes contain different materials. Generally, the process for obtaining recycled materials from the positive electrode is different from the process for obtaining recycled materials from the negative electrode.

[0005] A bipolar battery contains a bipolar electrode, which has a positive electrode and a negative electrode integrated together. To obtain recycled materials from the bipolar electrode, it is first necessary to separate the positive electrode and the negative electrode.

[0006] An object of the present disclosure is to provide a bipolar electrode that can be easily separated into a positive electrode and a negative electrode. [Means for solving the problem]

[0007] 1. One aspect of the present disclosure is a bipolar electrode. The bipolar electrode includes, in the perpendicular direction, a positive electrode composite layer, a positive electrode current collector foil, an intervening film, a negative electrode current collector foil, and a negative electrode composite layer, in this order. Each of the positive electrode current collector foil and the negative electrode current collector foil is attached to the intervening film. The positive electrode composite layer is attached to the positive electrode current collector foil. The negative electrode composite layer is attached to the negative electrode current collector foil. The intervening film is conductive. When the intervening film is stretched in the in-plane direction, at least one of the positive electrode current collector foil and the negative electrode current collector foil is configured to separate from the intervening film before the intervening film breaks.

[0008] The positive electrode composite layer and the positive electrode current collector foil constitute a positive electrode. The negative electrode composite layer and the negative electrode current collector foil constitute a negative electrode. Conventionally, the positive electrode current collector foil is adhered to the negative electrode current collector foil, for example, with an adhesive. For example, if a strong external force is applied perpendicular to the surface of the positive electrode current collector foil and the positive electrode current collector foil is peeled off from the negative electrode current collector foil, damage to each component can occur, resulting in contamination between the positive electrode and the negative electrode. This contamination can reduce the yield of recycled materials.

[0009] In the present disclosure, an intervening film connects the positive electrode current collector foil and the negative electrode current collector foil. The bipolar electrode in the present disclosure is configured such that at least one of the positive electrode current collector foil and the negative electrode current collector foil is separated from the intervening film by stretching the intervening film in the in-plane direction. In other words, by stretching the intervening film in the in-plane direction, the bipolar electrode can be easily separated into the positive electrode and the negative electrode.

[0010] 2. The bipolar electrode described in the above item "1" may include, for example, the following configuration: The intervening film has a greater total elongation at break than the positive electrode current collector foil and the negative electrode current collector foil.

[0011] Because the total elongation at break of the intervening film is greater than the total elongation at break of the positive and negative current collector foils, when the intervening film is stretched in the in-plane direction, the positive and negative current collector foils cannot keep up with the elongation (deformation) of the intervening film, which can result in the positive and negative current collector foils peeling off from the intervening film.

[0012] 3. The bipolar electrode according to the above item "1" or "2" may include, for example, the following configuration: In the in-plane direction, the intervening film protrudes outward beyond the positive electrode current collector foil and the negative electrode current collector foil.

[0013] The protruding portion of the intervening membrane can serve as a grip (handle) when stretching the intervening membrane.

[0014] 4. One aspect of the present disclosure is a bipolar battery. The bipolar battery includes the bipolar electrode described in any one of the above items "1" to "3."

[0015] 5. 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 electrode according to any one of the above items "1" to "3". (b) At least one of the positive electrode current collector foil and the negative electrode current collector foil is separated from the intervening film by stretching the intervening film in the in-plane direction.

[0016] 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]

[0017] [Figure 1] FIG. 2 is a schematic cross-sectional view showing an example of a bipolar electrode according to the present embodiment. [Figure 2] FIG. 2 is a schematic cross-sectional view showing a first separation mode. [Figure 3] FIG. 10 is a schematic cross-sectional view showing a second separation mode. [Figure 4] 1 is an example of a stress-strain diagram. [Figure 5]1 is a schematic cross-sectional view showing an example of a bipolar battery according to an embodiment of the present invention. [Figure 6] 1 is a schematic flowchart showing a method for producing recycled materials in this embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0018] -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.

[0019] The "perpendicular direction" refers to the normal direction to the surface of the electrode. The perpendicular direction can be rephrased as, for example, the thickness direction. The "in-plane direction" refers to any direction perpendicular to the perpendicular direction.

[0020] -Bipolar electrode- FIG. 1 is a schematic cross-sectional view showing an example of a bipolar electrode according to this embodiment. Bipolar electrode 10 includes, in the perpendicular-to-plane direction (Z-axis direction), a positive electrode composite layer 11, a positive electrode current collector foil 12, an intervening film 13, a negative electrode current collector foil 14, and a negative electrode composite layer 15, in this order. Bipolar electrode 10 may have any planar shape. For example, bipolar electrode 10 may have a rectangular planar shape. Bipolar electrode 10 is configured such that, when intervening film 13 is stretched in the in-plane direction, at least one of positive electrode current collector foil 12 and negative electrode current collector foil 14 separates from intervening film 13 before intervening film 13 breaks. The X-axis and Y-axis directions in FIG. 1 are examples of in-plane directions.

[0021] The positive electrode mixture layer 11 is attached to the positive electrode current collector foil 12. The thickness of the positive electrode mixture layer 11 may be, for example, 10 to 1000 μm. For example, grooves (not shown) may be formed in the positive electrode mixture layer 11. The positive electrode mixture layer 11 includes a positive electrode active material. The positive electrode active material may include any component. The positive electrode active material may include, for example, a layered lithium metal composite oxide, an olivine-type phosphate compound, or the like. The positive electrode active material may include various valuable metals. The positive electrode mixture layer 11 may further include, for example, a conductive material, a binder, or the like in addition to the positive electrode active material.

[0022] The positive electrode current collector foil 12 is attached to the interposing film 13. The positive electrode current collector foil 12 may have a thickness of, for example, 5 to 100 μm. The positive electrode current collector foil 12 may include, for example, aluminum foil, aluminum alloy foil, titanium foil, stainless steel foil, etc.

[0023] The negative electrode current collector foil 14 is attached to the interposing film 13. The negative electrode current collector foil 14 may have a thickness of, for example, 5 to 100 μm. The negative electrode current collector foil 14 may include, for example, copper foil, copper alloy foil, nickel foil, nickel alloy foil, etc.

[0024] The negative electrode mixture layer 15 is attached to the negative electrode current collector foil 14. The thickness of the negative electrode mixture layer 15 may be, for example, 10 to 1000 μm. The negative electrode mixture layer 15 includes a negative electrode active material. The negative electrode active material may include any component. The negative electrode active material may include, for example, silicon, silicon oxide, graphite, spinel-type titanium oxide, etc. The negative electrode mixture layer 15 may further include, in addition to the negative electrode active material, for example, a conductive material, a binder, etc.

[0025] The intervening film 13 is interposed between the positive electrode current collector foil 12 and the negative electrode current collector foil 14. The intervening film 13 bonds the positive electrode current collector foil 12 and the negative electrode current collector foil 14 together. The intervening film 13 has a first main surface and a second main surface. The second main surface is the surface opposite to the first main surface. The positive electrode current collector foil 12 may be attached to the first main surface. The negative electrode current collector foil 14 may be attached to the second main surface.

[0026] The thickness of the intervening film 13 may be, for example, 3 μm or more, 5 μm or more, or 10 μm or more. The thickness of the intervening film 13 may be, for example, 30 μm or less, 20 μm or less, or 15 μm or less.

[0027] The interposed film 13 may have a protruding portion 13a. In an in-plane direction (e.g., the X-axis direction), the protruding portion 13a protrudes outward relative to the positive electrode current collector foil 12 and the negative electrode current collector foil 14. The protruding amount (w) of the protruding portion 13a may be, for example, 1 mm or more, 5 mm or more, or 10 mm or more. The protruding amount (w) of the protruding portion 13a may be, for example, 20 mm or less, 15 mm or less, or 10 mm or less.

[0028] The intervening film 13 may be, for example, a self-supporting film. The intervening film 13 may include, for example, a resin film. The resin film may include, for example, a resin material, a rubber material, an elastomer material, or the like. The resin film may include, for example, a fluororesin, an acrylic resin, a polyimide resin, a polyester resin, a fluororubber, a urethane rubber, a silicone rubber, a fluoroelastomer, a urethane elastomer, or the like.

[0029] The intervening film 13 is electrically conductive (electronically conductive). The positive electrode current collector foil 12 and the negative electrode current collector foil 14 are electrically connected via the intervening film 13. The intervening film 13 may contain, for example, a conductive filler. For example, the resin film may be the continuous phase (matrix material) and the conductive filler may be the dispersed phase. The intervening film 13 may contain, for example, 1 to 50% by mass of the conductive filler, with the remainder being the resin film. The conductive filler may include, for example, metal particles, carbon black, carbon fibers, carbon nanotubes, etc.

[0030] The intervening film 13 has a bonding force. The intervening film 13 may contain, for example, an adhesive. For example, a conductive adhesive may be applied to both sides of the resin film. The conductive adhesive may contain, for example, a base agent, a curing agent, and a conductive filler. The base agent may contain, for example, an olefin-based resin. The curing agent may contain, for example, a compound having an isocyanate group. The conductive filler is as described above.

[0031] -Tensile properties- The interlayer 13 may have specific tensile properties. For example, the interlayer 13 may have a total elongation at break greater than those of the positive current collector foil 12 and the negative current collector foil 14. If the total elongation at break of the interlayer 13 is large, when the interlayer 13 is stretched in the in-plane direction, the positive current collector foil 12 and the negative current collector foil 14 cannot keep up with the elongation (deformation) of the interlayer 13 and may peel off.

[0032] Therefore, for example, when the interlayer 13 is stretched in the in-plane direction, if the positive current collector foil 12 peels off before the interlayer 13 breaks, it can be determined that the total elongation at break of the interlayer 13 is greater than the total elongation at break of the positive current collector foil 12. For example, when the interlayer 13 is stretched in the in-plane direction, if the negative current collector foil 14 peels off before the interlayer 13 breaks, it can be determined that the total elongation at break of the interlayer 13 is greater than the total elongation at break of the negative current collector foil 14.

[0033] 2 is a schematic cross-sectional view showing the first separated form. In the first separated form, for example, the following relationship may be satisfied. ε 11 <ε 12 <ε 13 ε 13 : Total elongation at break of interposed film 13 ε 11 : Total elongation at break of positive electrode mixture layer 11 ε 12 : Total elongation at break of positive electrode current collecting foil 12

[0034] "ε 11 <ε 12 <ε 13" relationship is satisfied, the positive electrode composite layer 11 may peel off from the positive electrode current collector foil 12, and then the positive electrode current collector foil 12 may peel off from the interposed film 13. That is, the positive electrode current collector foil 12 and the positive electrode composite layer 11 may be recovered separately. The first separation mode is suitable for a recycling process in which the positive electrode current collector foil 12 and the positive electrode composite layer 11 are treated separately. Furthermore, for example, a reduction in contamination from the positive electrode current collector foil 12 to the positive electrode composite and an improvement in recovery efficiency are also expected.

[0035] As with the positive electrode side, the negative electrode side may also satisfy, for example, the following relationship: ε 15 <ε 14 <ε 13 ε 13 : Total elongation at break of interposed film 13 ε 14 : Total elongation at break of negative electrode current collecting foil 14 ε 15 : Total elongation at break of negative electrode mixture layer 15

[0036] 3 is a schematic cross-sectional view showing the second separated form. In the second separated form, for example, the following relationship may be satisfied. ε 12 <ε 11 <ε 13 ε 13 : Total elongation at break of interposed film 13 ε 11 : Total elongation at break of positive electrode mixture layer 11 ε 12 : Total elongation at break of positive electrode current collecting foil 12

[0037] "ε 12 <ε 11 <ε 13" relationship is satisfied, the positive electrode mixture layer 11 and the positive electrode current collector foil 12 can be peeled off together from the interposing film 13. The second separation mode is suitable for a regeneration process in which the positive electrode mixture layer 11 and the positive electrode current collector foil 12 are treated together. For example, a process in which the positive electrode mixture layer 11 and the positive electrode current collector foil 12 are dissolved together can be considered. When the positive electrode mixture layer 11 and the positive electrode current collector foil 12 are treated together, for example, it is not necessary to consider a decrease in recovery efficiency due to adhesion of the positive electrode mixture to the positive electrode current collector foil 12.

[0038] As with the positive electrode side, the negative electrode side may also satisfy, for example, the following relationship: ε 14 <ε 15 <ε 13 ε 13 : Total elongation at break of interposed film 13 ε 14 : Total elongation at break of negative electrode current collecting foil 14 ε 15 : Total elongation at break of negative electrode mixture layer 15

[0039] The total elongation at break of the positive electrode current collector foil 12, ε 12 ” relative to the total elongation at break of the interposed film 13 “ε 13 " ratio "ε 13 / ε 12 The ratio of total elongation at break "ε" may be, for example, 1.001 or more, 1.01 or more, 1.03 or more, 1.05 or more, 1.1 or more, 1.2 or more, 1.5 or more, or 2 or more. 13 / ε 12 " may be, for example, 10 or less, 5 or less, 3 or less, or 2 or less.

[0040] The total elongation at break of the positive electrode current collector foil 12, ε 12 ” relative to the total elongation at break “ε 11 " ratio "ε 11 / ε 12 The ratio of total elongation at break "ε" may be, for example, 0.1 or more, 0.3 or more, 0.5 or more, 0.7 or more, 1 or more, 2 or more, 3 or more, or 5 or more. 11 / ε 12" may be, for example, 10 or less, 5 or less, 3 or less, 2 or less, 1 or less, 0.7 or less, 0.5 or less, or 0.3 or less.

[0041] The total elongation at break of the negative electrode current collector foil 14, ε 14 ” relative to the total elongation at break of the interposed film 13 “ε 13 " ratio "ε 13 / ε 14 The ratio of total elongation at break "ε" may be, for example, 1.001 or more, 1.01 or more, 1.03 or more, 1.05 or more, 1.1 or more, 1.2 or more, 1.5 or more, or 2 or more. 13 / ε 14 " may be, for example, 10 or less, 5 or less, 3 or less, or 2 or less.

[0042] The total elongation at break of the negative electrode current collector foil 14, ε 14 ” relative to the total elongation at break “ε 15 " ratio "ε 15 / ε 14 The ratio of total elongation at break "ε" may be, for example, 0.1 or more, 0.3 or more, 0.5 or more, 0.7 or more, 1 or more, 2 or more, 3 or more, or 5 or more. 15 / ε 14 " may be, for example, 10 or less, 5 or less, 3 or less, 2 or less, 1 or less, 0.7 or less, 0.5 or less, or 0.3 or less.

[0043] FIG. 4 shows an example of a stress-strain diagram. A stress-strain diagram can be obtained by tensile testing each component. For example, a tensile testing machine compliant with JIS B 7721 Class 1 or higher can be used. Test specimens of the same size are prepared from each component. The test force may be adjusted, for example, within a range of 100 to 300 MPa. The strain rate may be adjusted, for example, within a range of 0.01 to 1% / s. The vertical axis of the stress-strain diagram represents stress, and the horizontal axis represents strain. Three measurement examples are shown in FIG. 4. The stress-strain curve may or may not have a yield point. In either case, the total elongation at break (ε) is the sum of the elastic elongation and plastic elongation of the extensometer at break. The total elongation at break is expressed as a percentage of the extensometer gauge length.

[0044] The total elongation at break of the intervening film 13 can be adjusted, for example, by the type of resin material or the type of conductive filler (e.g., fibrous conductive filler). The total elongation at break of the positive electrode current collector foil 12 and the negative electrode current collector foil 14 can be adjusted, for example, by the type of metal foil (alloy material). The total elongation at break of the positive electrode composite layer 11 and the negative electrode composite layer 15 can be adjusted, for example, by the type of binder or the mass fraction (mixture amount) of the binder. For example, by selecting a fibrous binder (e.g., polytetrafluoroethylene) or a binder with high extensibility (e.g., polyvinylidene fluoride), it is expected that the total elongation at break of the composite layer will increase.

[0045] -Bipolar battery- 5 is a schematic cross-sectional view showing an example of a bipolar battery according to this embodiment. The bipolar battery 100 may include an exterior body 90, a power generating element 50, and an electrolyte (not shown). 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 exterior body 90 houses the power generating element 50.

[0046] The power generating element 50 includes a bipolar electrode 10, a separator 20, an electrolyte (not shown), and a sealing material 30. That is, the bipolar battery 100 includes a bipolar electrode 10. The multiple bipolar electrodes 10 are stacked in the direction perpendicular to the surface (Z-axis direction). That is, the direction perpendicular to the surface of the bipolar electrodes 10 corresponds to the stacking direction of the power generating element 50.

[0047] The power generating element 50 may further include a terminal unit in addition to the bipolar electrode 10. The terminal unit is disposed at an end in the stacking direction. The terminal unit may have, for example, a monopolar structure. The terminal unit may be composed of, for example, a positive electrode composite layer 11 and a positive electrode current collector foil 12. The terminal unit may be composed of, for example, a negative electrode composite layer 15 and a negative electrode current collector foil 14.

[0048] The separator 20 is disposed between the bipolar electrodes 10. The separator 20 separates the adjacent positive electrode composite layer 11 and negative electrode composite layer 15. The separator 20 may include, for example, a porous membrane. The area surrounded by the positive electrode current collector foil 12 and the negative electrode current collector foil 14, sandwiching the separator 20, constitutes a unit battery (cell). Because the bipolar battery 100 includes multiple cells, it may also be referred to as, for example, a "bipolar module." Each cell is filled with an electrolyte.

[0049] The sealing material 30 fills the gaps between the bipolar electrodes 10 at the periphery in the in-plane direction. The sealing material 30 may contain, for example, an epoxy resin. The sealing material 30 may have, for example, a lower melting point than the intervening film 13. For example, when the power generating element 50 is disassembled, the sealing material 30 may be selectively melted to separate the intervening film 13 from the sealing material 30. The difference in melting point between the sealing material 30 and the intervening film 13 may be, for example, 10°C or more, 30°C or more, 50°C or more, or 100°C or more. The difference in melting point between the sealing material 30 and the intervening film 13 may be, for example, 200°C or less, 150°C or less, or 100°C or less.

[0050] The sealing material 30 may have a thermal decomposition temperature that is lower than the melting point of the intervening film 13, for example. For example, when the power generating element 50 is disassembled, the sealing material 30 may be thermally decomposed, thereby separating the intervening film 13 from the sealing material 30. The difference between the thermal decomposition temperature of the sealing material 30 and the melting point of the intervening film 13 may be, for example, 10°C or more, 30°C or more, 50°C or more, or 100°C or more. The difference between the thermal decomposition temperature of the sealing material 30 and the melting point of the intervening film 13 may be, for example, 200°C or less, 150°C or less, or 100°C or less.

[0051] At one end in the stacking direction, the positive electrode current collector foil 12 is attached to the first current collector plate 91. At the other end in the stacking direction, the negative electrode current collector foil 14 is attached to the second current collector plate 94.

[0052] In another embodiment of the present disclosure, the bipolar battery 100 may be an all-solid-state battery. The all-solid-state battery includes a solid electrolyte instead of an electrolytic solution. The all-solid-state battery may include, for example, a sulfide solid electrolyte.

[0053] -Method of manufacturing recycled materials- 6 is a schematic flowchart showing the method for producing a recycled material according to this embodiment. Hereinafter, the "method for producing a recycled material according to this embodiment" may be abbreviated as "this method." This method includes "(a) preparation of a bipolar electrode" and "(b) separation."

[0054] -(a) Preparation of bipolar electrodes- The method includes preparing a bipolar electrode 10. For example, the bipolar electrode 10 may be recovered by dismantling an unnecessary bipolar battery 100. For example, the bipolar electrode 10 may be recovered from a defective product discarded during the manufacturing process of batteries and electrodes.

[0055] -(b) Separation- This method includes separating at least one of positive electrode current collector foil 12 and negative electrode current collector foil 14 from intervening film 13 by stretching intervening film 13 in the in-plane direction. Either positive electrode current collector foil 12 or negative electrode current collector foil 14 may be separated, or both positive electrode current collector foil 12 and negative electrode current collector foil 14 may be separated. Furthermore, as shown in a first separation form ( FIG. 2 ), at least one of positive electrode composite layer 11 and negative electrode composite layer 15 may be separated.

[0056] For example, the protruding portion 13a of the intervening film 13 may be clamped. For example, the intervening film 13 may be uniaxially stretched. For example, the intervening film 13 may be biaxially stretched. The biaxial stretching may be simultaneous biaxial stretching or sequential biaxial stretching. For example, the stretching may be performed by an inching operation.

[0057] The various components separated from the interposed film 13 are collected. The various components can be recycled by any method. For example, the various components may be reused. For example, battery materials (current collector foil, active material, etc.) may be recycled using components extracted from the various components. For example, the materials may be reused for applications other than batteries. [Explanation of symbols]

[0058] 10 bipolar electrode, 11 positive electrode composite layer, 12 positive electrode current collector foil, 13 interposed film, 13a protrusion, 14 negative electrode current collector foil, 15 negative electrode composite layer, 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 positive electrode composite layer, a positive electrode current collecting foil, an intervening film, a negative electrode current collecting foil, and a negative electrode composite layer, arranged in this order in the perpendicular direction; each of the positive electrode current collector foil and the negative electrode current collector foil is attached to the interposing film; the positive electrode mixture layer is attached to the positive electrode current collector foil, the negative electrode mixture layer is attached to the negative electrode current collector foil, The intervening film is electrically conductive, and when the intervening film is stretched in an in-plane direction, at least one of the positive electrode current collector foil and the negative electrode current collector foil is separated from the intervening film before the intervening film is broken. Bipolar electrodes.

2. the intervening film has a greater total elongation at break than the positive electrode current collector foil and the negative electrode current collector foil; 10. The bipolar electrode of claim 1.

3. the intervening film protrudes outward beyond the positive electrode current collector foil and the negative electrode current collector foil in the in-plane direction; 10. The bipolar electrode of claim 1.

4. A bipolar electrode according to any one of claims 1 to 3, Bipolar battery.

5. (a) providing a bipolar electrode according to any one of claims 1 to 3; and (b) separating at least one of the positive electrode current collector foil and the negative electrode current collector foil from the intervening film by stretching the intervening film in the in-plane direction; Including, How recycled materials are produced.

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