Bipolar collector, bipolar electrode, bipolar battery, and method for manufacturing bipolar collector

Abstract

To reduce the amount of usage of metal.SOLUTION: The bipolar collector includes a first metal foil, an adhesive layer, and a second metal foil. The first metal foil includes a first main surface and a second main surface. The second main surface is the opposite surface to the first main surface. The adhesive layer covers the first main surface. The adhesive layer has an electron conduction property. The second metal foil is attached to the first main surface by the adhesive layer. The second metal foil has a frame-like flat surface. The second metal foil is attached along the periphery of the first main surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a bipolar current collector, a bipolar electrode, a bipolar battery, and a method for manufacturing a bipolar current collector.

Background Art

[0002] Japanese Unexamined Patent Application Publication No. 2023-053669 discloses a bipolar current collector.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A bipolar current collector is an electrode current collector for a bipolar battery. Conventionally, a bipolar current collector has been manufactured by laminating two types of metal foils. For example, from the viewpoint of effective utilization of resources and the like, reduction of the amount of metal used is desired.

[0005] An object of the present disclosure is to reduce the amount of metal used.

Means for Solving the Problems

[0006] 1. The bipolar current collector includes a first metal foil, an adhesive layer, and a second metal foil. The first metal foil has a first main surface and a second main surface. The second main surface is the opposite surface of the first main surface. The adhesive layer covers the first main surface. The adhesive layer has electronic conductivity. The second metal foil is adhered to the first main surface by the adhesive layer. The second metal foil has a frame-shaped planar shape. The second metal foil is attached along the periphery of the first main surface.

[0007] Since the second metal foil is in a frame shape, the amount of metal used is reduced. When the second metal foil is in a frame shape, there is a possibility that the first main surface of the first metal foil may corrode due to contact with the electrolytic solution. However, since the adhesive layer covers the first main surface, the adhesive layer can inhibit the contact between the first main surface and the electrolytic solution. Furthermore, since the adhesive layer has conductivity, electrons can conduct in the thickness direction of the bipolar current collector. The frame-shaped second metal foil can contribute to the sealing property of the bipolar battery. By filling a sealing material between the second metal foil (frame) and the first metal foil, an improvement in the sealing property is expected. If there is no second metal foil (frame), adhesiveness with the sealing material is required for the adhesive layer. That is, the range of material selection for the adhesive layer and the sealing material will be narrowed. It is expected that the degree of freedom in material selection will increase due to the presence of the second metal foil (frame).

[0008] 2. The bipolar current collector described in the above "1" may include, for example, the following configuration. The first metal foil contains aluminum. The adhesive layer contains a resin material and a conductive filler. The second metal foil contains copper.

[0009] In the bipolar current collector described in the above "2", the amount of copper used can be reduced.

[0010] 3. The bipolar electrode includes the bipolar current collector, the positive electrode layer, and the negative electrode layer described in the above "1" or "2". The positive electrode layer is disposed on the second main surface. The negative electrode layer is disposed on the adhesive layer.

[0011] For example, the first main surface of the first metal foil may be on the negative electrode side and the second main surface may be on the positive electrode side. Of course, a form in which the first main surface is on the positive electrode side and the second main surface is on the negative electrode side is also conceivable.

[0012] 4. The bipolar battery includes a plurality of bipolar electrodes, an electrolytic solution, and a sealing material. Each of the plurality of bipolar electrodes is the bipolar electrode described in the above "3". The plurality of bipolar electrodes are laminated in the thickness direction. The sealing material seals between the second main surface and the second metal foil between two adjacent bipolar electrodes.

[0013] 5. The method for manufacturing a bipolar current collector includes the following (a) to (c). (a) Prepare a first metal foil and a second metal foil. (b) Form an adhesive layer by applying an adhesive to one side of the first metal foil. (c) Manufacture a bipolar current collector by attaching the second metal foil to the adhesive layer. The adhesive layer has electronic conductivity. The second metal foil includes a portion having a frame-shaped planar shape. The second metal foil is attached along the periphery of the first metal foil.

[0014] Hereinafter, embodiments of the present disclosure (hereinafter may be abbreviated as "the present embodiment"), and examples of the present disclosure (hereinafter may be abbreviated as "the present example") will be described. However, the present embodiment and the present example do not limit the technical scope of the present disclosure. The present embodiment and the present example are illustrative in all respects. The present embodiment and the present example are non-limiting. The technical scope of the present disclosure includes all modifications within the meaning and scope equivalent to the description of the claims. For example, any configuration is extracted from the present embodiment, and their arbitrary combinations are also initially planned.

[0015] Geometric terms (such as parallel, perpendicular, orthogonal, etc.) should not be construed in a strict sense. For example, "parallel" may deviate slightly from "parallel" in the strict sense. Geometric terms may include, for example, tolerances, errors, etc. in design, work, manufacturing, etc. The dimensional relationships in each figure may not match the actual dimensional relationships. The dimensional relationships in each figure may be changed to assist the reader's understanding. For example, the length, width, thickness, etc. may be changed. Some configurations may be omitted.

[0016] A numerical range such as "from m to n%" includes the upper and lower limit values, unless otherwise specified. "From m to n%" indicates a numerical range of "m% or more and n% or less". "m% or more and n% or less" includes "more than m% and less than n%".

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 8

Figure 9

Figure 10

Modes for Carrying Out the Invention

[0018] <Bipolar Current Collector> FIG. 1 is a schematic plan view showing an example of a bipolar current collector according to the present embodiment. FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1. The bipolar current collector 10 includes a first metal foil 11, an adhesive layer 13, and a second metal foil 12. For convenience, the adhesive layer 13 is not shown in FIG. 1. As shown in FIG. 2, the first metal foil 11 has a first main surface 11a and a second main surface 11b. The second main surface 11b is the opposite surface of the first main surface 11a. The adhesive layer 13 covers the first main surface 11a. The second metal foil 12 is adhered to the first main surface 11a by the adhesive layer 13. As shown in FIG. 1, the second metal foil 12 has a frame-shaped planar shape. The second metal foil 12 is attached along the periphery of the first main surface 11a. The width dimension (w) of the second metal foil 12 may be, for example, 1 to 50 mm, 1 to 30 mm, or 1 to 10 mm.

[0019] The ratio of the area of the portion surrounded by the second metal foil 12 (frame) to the area of the entire first main surface 11a may be, for example, 0.95 or less, 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, or 0.2 or less. The ratio of the same areas may be, for example, 0.1 or more, 0.2 or more, 0.3 or more, 0.4 or more, 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, or 0.9 or more.

[0020] ·First metal foil, second metal foil The first metal foil 11 and the second metal foil 12 are made of different materials from each other. As long as they are made of different materials from each other, the first metal foil 11 and the second metal foil 12 may include any metal material. The first metal foil 11 and the second metal foil 12 may include, for example, at least one selected from the group consisting of aluminum (Al), copper (Cu), nickel (Ni), titanium (Ti), iron (Fe), and stainless steel (SUS).

[0021] The first metal foil 11 may contain, for example, Al. That is, the first metal foil 11 may be an Al foil. The Al foil in this embodiment includes pure Al foil and Al alloy foil. The Al foil may contain any metal material represented by alloy numbers from 1000 to 8000 described in "JIS H 4000", for example. The thickness of the first metal foil 11 may be, for example, 1 to 100 μm, 5 to 75 μm, or 10 to 50 μm.

[0022] The second metal foil 12 may contain, for example, Cu. That is, the second metal foil 12 may be a Cu foil. The Cu foil in this embodiment includes pure Cu foil and Cu alloy foil. The Cu foil may contain any metal material represented by alloy numbers from 1000 to 7000 described in "JIS H 3100", for example. The thickness of the second metal foil 12 may be, for example, 1 to 50 μm, 3 to 30 μm, or 5 to 10 μm.

[0023] ·Adhesive layer The adhesive layer 13 has electronic conductivity. The adhesive layer 13 may contain, for example, a resin material and a conductive filler. For example, the adhesive layer 13 may contain 1 to 99% by mass of the conductive filler and the balance of the resin material. The mass fraction of the conductive filler may be, for example, 5 to 50% or 10 to 30%.

[0024] The resin material is an adhesive component. The resin material may have resistance to the electrolytic solution. The resin material may be insoluble in the electrolytic solution. The resin material may contain, for example, at least one selected from the group consisting of olefin resins, urethane resins, polyamide resins, cellulose resins, polyether resins, acrylic resins, epoxy resins, and polyester resins. The resin material may contain, for example, one-component adhesives, two-component adhesives, etc. In the two-component adhesive, the main agent may contain, for example, an olefin resin or the like. The curing agent may contain, for example, a compound having an isocyanate group or the like.

[0025] The conductive filler is a conductive component. The conductive filler may contain, for example, carbon particles, metal particles, metal-plated particles, etc. The core of the metal-plated particles may be solid or hollow resin particles. The conductive filler may contain at least one selected from the group consisting of, for example, carbon black, graphite, vapor-grown carbon fibers, carbon nanotubes, carbon nanofibers, carbon nanospheres, Ni particles, Ni-plated particles, Cu particles, and Cu-plated particles. The particle shape of the conductive filler is arbitrary. The conductive filler may be, for example, spherical, flake-shaped, rod-shaped, needle-shaped, fibrous, etc.

[0026] The particle diameter of the conductive filler may be, for example, 0.1 to 10 μm, 0.5 to 5 μm, or 1 to 3 μm. "Particle diameter" indicates the average value of the maximum Feret diameter in the particle image. The average value is calculated from the measurement results of 10 times or more. The ratio of the thickness of the adhesive layer 13 to the particle diameter of the conductive filler may be, for example, 0.5 to 2, or 0.8 to 1.2. The thickness of the adhesive layer 13 may be, for example, 1 to 10 μm, 1 to 5 μm, or 2 to 4 μm. When the thickness of the adhesive layer 13 is 2 μm or more, an improvement in the electrolyte permeation resistance is expected.

[0027] ·Through resistance The through resistance indicates the resistance when electrons flow through the first metal foil 11 and the adhesive layer 13 in the thickness direction. The through resistance of the bipolar current collector 10 may be, for example, 150 mΩ or less. The through resistance may be, for example, 125 mΩ or less, 100 mΩ or less, or 75 mΩ or less. The through resistance may be, for example, 10 mΩ or more, or 50 mΩ or more.

[0028] <Method for manufacturing bipolar current collector> Figure 3 is a schematic flowchart of a method for manufacturing a bipolar current collector according to the present embodiment. Hereinafter, the "method for manufacturing a bipolar current collector according to the present embodiment" may be abbreviated as the "present manufacturing method". The present manufacturing method includes "(a) preparation of metal foils", "(b) formation of an adhesive layer", and "(c) bonding". Note that the order in Figure 3 is merely an example. For example, a plurality of steps may proceed simultaneously. For example, a plurality of steps may proceed in sequence. Figure 4 is a conceptual diagram showing an example of a manufacturing apparatus according to the present embodiment. The manufacturing apparatus 200 can implement the present manufacturing method. The bipolar current collector 10 may be manufactured, for example, by a roll-to-roll method. The arrow in Figure 4 indicates the conveyance direction of the workpiece.

[0029] ·(a) Preparation of metal foils Figure 5 is a schematic plan view showing an example of a first metal foil and a second metal foil. The present manufacturing method includes preparing a first metal foil 11 and a second metal foil 12. As the first metal foil 11, for example, a strip-shaped Al foil may be prepared.

[0030] The second metal foil 12 is prepared so as to include a portion having a frame-shaped planar shape. In the second metal foil 12, the portion having a frame-shaped planar shape may be singular or plural. For example, the second metal foil 12 may be manufactured by punching. For example, a strip-shaped Cu foil may be prepared. For example, punching may be performed at a constant pitch in the length direction of the strip-shaped Cu foil. The punched portion 12a may be reused, for example, in the manufacture of Cu foil.

[0031] As long as punching is performed so that a frame-shaped portion is formed, the planar shape of the punched portion 12a (hole) is arbitrary. The planar shape of the punched portion 12a may be, for example, rectangular. Figure 6 is a first schematic plan view showing an example of the second metal foil. The planar shape of the punched portion 12a may be, for example, elliptical, circular, or the like. Figure 7 is a second schematic plan view showing an example of the second metal foil. For example, the metal foil may be left so as to bridge two opposing sides (frames).

[0032] · (b) Formation of the Adjacent Layer This manufacturing method includes forming an adhesive layer 13 by applying an adhesive 3 to one side (the first main surface 11a) of the first metal foil 11. For example, the adhesive 3 may be prepared by mixing a main agent, a curing agent, and a conductive filler. The application method is arbitrary. For example, as shown in FIG. 4, the adhesive 3 may be applied to the first metal foil 11 by a gravure roll 201. The adhesive 3 may be dried, for example, by a drying furnace 202.

[0033] · (c) Lamination This manufacturing method includes manufacturing the bipolar current collector 10 by attaching a second metal foil 12 to the adhesive layer 13. For example, the lamination may be performed by dry lamination processing. For example, the second metal foil 12 may be laminated to the first metal foil 11 by a hot roll 203. The second metal foil 12 is attached along the periphery of the first metal foil 11 (the first main surface 11a).

[0034] The bipolar current collector 10 may be cut according to the electrode shape. The cutting may be performed before the formation of the positive electrode layer 21 and the negative electrode layer 22, or after the formation of the positive electrode layer 21 and the negative electrode layer 22. The dashed-dotted line in FIGS. 5 to 7 shows an example of the cutting line.

[0035] <Bipolar Electrode> FIG. 8 is a schematic cross-sectional view showing an example of the bipolar electrode in the present embodiment. The bipolar electrode 20 is an electrode for a bipolar battery. The bipolar electrode 20 includes a bipolar current collector 10, a positive electrode layer 21, and a negative electrode layer 22. The positive electrode layer 21 is disposed on the second main surface 11b. "On the second main surface 11b" can be paraphrased as the surface of the second main surface 11b. The same applies to "on the adhesive layer 13" described later.

[0036] The positive electrode layer 21 contains a positive electrode composite material. The positive electrode composite material may include, for example, a positive electrode active material, a conductive material, a binder, and the like. The positive electrode active material may include, for example, a lithium nickel composite oxide, lithium iron phosphate, and the like. The conductive material may include, for example, carbon black and the like. The binder may include polyvinylidene fluoride and the like. The thickness of the positive electrode layer 21 may be, for example, 10 to 500 μm, 50 to 300 μm, or 100 to 200 μm.

[0037] The negative electrode layer 22 is disposed on the adhesive layer 13. The negative electrode layer 22 may have a larger area than the positive electrode layer 21. The ratio of the area of the negative electrode layer 22 to the area of the positive electrode layer 21 may be, for example, 1.05 to 1.15. The negative electrode layer 22 may extend so as to cover a part of the second metal foil 12. The negative electrode layer 22 contains a negative electrode composite material. The negative electrode composite material may include, for example, a negative electrode active material, a conductive material, a binder, and the like. The negative electrode active material may include, for example, graphite, silicon, silicon oxide, and the like. The conductive material may include, for example, carbon black and the like. The binder may include styrene-butadiene rubber, carboxymethyl cellulose, and the like. The thickness of the negative electrode layer 22 may be, for example, 10 to 500 μm, 50 to 300 μm, or 100 to 200 μm.

[0038] <Bipolar battery> FIG. 9 is a schematic cross-sectional view showing an example of the bipolar battery in the present embodiment. The bipolar battery 100 includes a bipolar electrode 20, an electrolytic solution (not shown), and a sealing material 40. The bipolar battery 100 may include, for example, an exterior body (not shown). The exterior body may house the bipolar electrode 20 and the electrolytic solution. The exterior body may be, for example, a pouch made of a metal foil laminate film, a metal case, or the like.

[0039] The electrolyte is a liquid electrolyte. The electrolyte may contain, for example, a supporting salt and a solvent. The supporting salt may contain, for example, LiPF6 or the like. The solvent may contain, for example, ethylene carbonate, ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, or the like. The electrolyte may further contain any additive.

[0040] The plurality of bipolar electrodes 20 are stacked in the thickness direction (Z direction). The bipolar battery 100 may further include a separator 30. The separator 30 is disposed between the positive electrode layer 21 and the negative electrode layer 22. The separator 30 separates the positive electrode layer 21 from the negative electrode layer 22. The separator 30 may contain, for example, a porous film made of resin or the like.

[0041] The sealing material 40 seals between the second main surface 11b and the second metal foil 12 (frame) between two adjacent bipolar electrodes 20. In the XY plane, the sealing material 40 surrounds the periphery of the positive electrode layer 21 and the negative electrode layer 22. The sealing material 40 may include, for example, a first sealing material 41 (primary sealing) and a second sealing material 42 (secondary sealing). The first sealing material 41 may seal between the second main surface 11b and the second metal foil 12. The second sealing material 42 may further seal the outside of the first sealing material 41. The sealing material 40 includes, for example, a resin material. The sealing material may contain, for example, at least one selected from the group consisting of polypropylene, polyphenylene sulfide, and modified polyphenylene ether. The second sealing material 42 may be the same material as the first sealing material 41 or a different material.

Example

[0042] <Preparation of Sample> ·No.1 The following materials were prepared.

[0043] First metal foil 11: Al foil Second metal foil 12: Cu foil (already punched, punched portion 12a: rectangular shape) Main agent: olefin resin Hardening agent: isocyanate compound Conductive filler: Ni-plated particles

[0044] The adhesive 3 was prepared by mixing the main agent, hardening agent and conductive filler. The first metal foil 11, the second metal foil 12 and the adhesive 3 were set in the manufacturing apparatus 200 (see Fig. 4). Under the following conditions, the bipolar current collector 10 was manufactured.

[0045] Line speed (work transfer speed): 15 m / min Gravure roll 201: elongate, 75 lines Set temperature of the drying oven 202: 150°C Surface temperature of the hot roll 203: 90°C Nip pressure of the hot roll 203: 0.45 MPa

[0046] ·No.2 The bipolar current collector 10 was manufactured in the same manner as No.1, except that a Cu foil (unprocessed product, no holes) was used as the second metal foil 12.

[0047] <Evaluation> Fig. 10 is a table showing the evaluation results. "Standard" and "Target" in Fig. 10 are values for the samples of this experiment. No.1 (framed Cu foil) showed a through-resistance equivalent to that of No.2 (ordinary Cu foil). The quality (minimum thickness, average thickness) of the adhesive layer 13 of No.1 was also sufficient. Therefore, sufficient permeation resistance against the electrolytic solution is expected. In No.1, the coatability of the composite material was also evaluated by applying the negative electrode composite material onto the adhesive layer 13. The coatability of No.1 was equivalent to that of No.2.

Explanation of symbols

[0048] 3 Adhesive, 10 Bipolar current collector, 11 First metal foil, 11a First main surface, 11b Second main surface, 12 Second metal foil, 12a Portion, 13 Adhesive layer, 20 Bipolar electrode, 21 Positive electrode layer, 22 Negative electrode layer, 30 Separator, 40 Sealing material, 41 First sealing material, 42 Second sealing material, 100 Bipolar battery, 200 Manufacturing apparatus, 201 Gravure roll, 202 Drying furnace, 203 Heating roll.

Claims

1. A first metal foil, An adhesive layer, and A second metal foil, comprising, The first metal foil has a first main surface and a second main surface, The second main surface is the opposite surface of the first main surface, The adhesive layer covers the first main surface, The adhesive layer has electronic conductivity, The second metal foil is adhered to the first main surface by the adhesive layer, The second metal foil has a frame-shaped planar shape and The second metal foil is attached along the periphery of the first main surface. A bipolar current collector.

2. The first metal foil contains aluminum, The adhesive layer contains a resin material and a conductive filler, and The second metal foil contains copper. The bipolar current collector according to Claim 1.

3. The bipolar current collector according to Claim 1 or Claim 2, A positive electrode layer, and A negative electrode layer, comprising, The positive electrode layer is disposed on the second main surface, and The negative electrode layer is disposed on the adhesive layer. A bipolar electrode.

4. A plurality of bipolar electrodes, An electrolytic solution, and A sealing material, comprising, Each of the plurality of bipolar electrodes is the bipolar electrode according to Claim 3, The plurality of bipolar electrodes are stacked in the thickness direction, and The sealing material seals between the second main surface and the second metal foil between two adjacent bipolar electrodes. Bipolar battery.

5. (a) Preparing a first metal foil and a second metal foil; (b) Forming an adhesive layer by applying an adhesive to one side of the first metal foil; and (c) Manufacturing a bipolar current collector by attaching the second metal foil to the adhesive layer. comprising the adhesive layer has electronic conductivity; the second metal foil includes a portion having a frame-shaped planar shape, and the second metal foil is attached along the periphery of the first metal foil. Method for manufacturing a bipolar current collector.

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