Manufacturing method for current collector foil

Abstract

To provide a manufacturing method for a current collector foil whereby generation of pinholes can be reduced.SOLUTION: A manufacturing method for a current collector foil, includes: a first step of applying an adhesive to one surface of a first metal foil; a second step of bonding a second metal foil to the surface of the first metal foil to which the adhesive has been applied, and applying heat and pressure thereto to obtain a bonded foil; and a third step of winding and heating the bonded foil; wherein, in the third step, the winding tensile force of the bonded foil is 316 N / m or more; and wherein, in the third step, the heating temperature of the bonded foil is equal to or higher than a fusing point of a main agent of the adhesive.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a method for manufacturing a current collector foil. [Background technology]

[0002] Various techniques have been proposed for manufacturing current collector foils as disclosed in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. H08-007926 [Patent Document 2] JP 2023-053669 A Summary of the Invention [Problem to be solved by the invention]

[0004] The current collector foil used in bipolar batteries is, for example, a clad material in which aluminum (Al) foil and copper (Cu) foil are bonded together. It is known that the current collector foil is manufactured by rolling aluminum foil and copper foil. From the viewpoint of improving the battery capacity, it is preferable that this current collector foil is thin. If the current collector foil is made thin, pinholes may occur in the current collector foil. If pinholes exist, they may become larger during charging and discharging. As a method for solving the above problems, for example, Patent Document 2 proposes a current collector foil having an anodized aluminum layer with Ni portions formed in pores between Al-Cu. However, the anodizing process is costly. In addition, this technology has problems such as the anodized aluminum layer being formed on the Al foil, so that if there are pinholes in the Al foil, the anodized aluminum layer is not formed in the pinholes in the Al foil.

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a manufacturing method for a current collector foil that can reduce the occurrence of pinholes. [Means for solving the problem]

[0006] That is, the present disclosure includes the following aspects. <1> A first step of applying an adhesive to one side of a first metal foil; A second step of laminating a second metal foil to the surface of the first metal foil to which the adhesive is applied, and then heating and pressing the second metal foil to obtain a laminated foil; A third step of winding and heating the laminated foil, In the third step, the winding tension of the laminated foil is 316 N / m or more; The method for producing a current collector foil, wherein in the third step, the heating temperature of the laminated foil is equal to or higher than the melting point of the main agent of the adhesive.

[0007] <2> In the third step, the laminated foil is wound up so that a pressure of 1.6 kPa or more is applied thereto. <1> A method for producing the current collector foil according to claim 1.

[0008] <3> The base material of the adhesive is a polyolefin resin. <1> or the above <2> A method for producing the current collector foil according to claim 1.

[0009] <4> <1> ~ <3> 13. A method for producing a battery using a current collecting foil obtained by the method according to claim 12. Effect of the Invention

[0010] The method for producing a current collector foil according to the present disclosure can reduce the occurrence of pinholes. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a schematic diagram showing an example of a bonding apparatus (dry lamination). [Diagram 2] FIG. 2 is a graph showing the results of CAE calculations of compressive stress acting on the laminated foil during winding of the laminated foil versus the radial position from the center of the roll in the third step of Examples 1 and 2 and Comparative Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, embodiments of the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of the current collector foil that do not characterize the present disclosure) can be understood as design matters of a person skilled in the art based on the prior art in the field. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships.

[0013] In the present disclosure, a first step includes applying an adhesive to one side of a first metal foil; A second step of laminating a second metal foil to the surface of the first metal foil to which the adhesive is applied, and then heating and pressing the second metal foil to obtain a laminated foil; A third step of winding and heating the laminated foil, In the third step, the winding tension of the laminated foil is 316 N / m or more; The present invention provides a method for producing a current collector foil, wherein in the third step, the heating temperature of the laminated foil is equal to or higher than the melting point of the main agent of the adhesive.

[0014] In the present disclosure, a laminated foil is produced by laminating a first metal foil and a second metal foil together using a dry laminator. The adhesive between the first metal foil and the second metal foil is made to flow by setting the winding tension of the laminated foil to a predetermined value or higher and the heating temperature of the laminated foil during aging to a melting point of the adhesive or higher, so that the adhesive flows into pinholes on the metal foils where there is no adhesive during lamination, thereby reducing the occurrence of pinholes in the current collecting foil.

[0015] The method for producing a current collector foil according to the present disclosure includes a first step, a second step, and a third step.

[0016] (1st step) The first step is to apply an adhesive to one side of a first metal foil. The method of applying the adhesive is not particularly limited, and for example, the first metal foil in a roll form may be unwound and the adhesive may be applied using a doctor blade, a gravure roll, or the like. The adhesive may then be dried using hot air or the like in a drying oven. The temperature of the drying oven may be, for example, 150° C. or higher.

[0017] The base material of the adhesive may be a polyolefin resin. Here, the polyolefin resin refers to a resin containing 50% by mass or more of olefin as a structural unit relative to the total mass of the structural units contained in the entire resin. By using the polyolefin resin, the corrosion resistance against the electrolyte can be improved. The polyolefin resin is preferably an acid-modified polyolefin resin. Examples of the acid-modified polyolefin resin include polyolefin resins modified with an unsaturated carboxylic acid; polyolefin resins modified with an unsaturated carboxylic anhydride; and the like. Examples of the acid-modified polyolefin resin include maleic anhydride-modified polypropylene. Specific examples of the acid-modified polyolefin resin include acid-modified polyolefin resins contained in Mitsui Chemical's UNISTOL (R-200X, R-303XE, E-200EM, A-200PM, A-201PM, H-100, H-200, XP01A, XP01B / 11B, XP03F, XP04A, etc. UNISTOL is a registered trademark), etc. The content of the base agent may be 50% by mass or more based on the total mass of the adhesive.

[0018] The melting point of the main agent of the adhesive is, for example, preferably 30°C or higher and 80°C or lower, more preferably 40°C or higher and 75°C or lower, and even more preferably 45°C or higher and 70°C or lower. The melting point of the base material is a value measured by a known melting point measuring device.

[0019] The adhesive may contain a conductive additive, which may be Ni-plated particles or the like. The content of the conductive assistant is not particularly limited. The adhesive may include a hardener. The content of the curing agent is not particularly limited. The hardener may be an epoxy resin or the like.

[0020] Examples of metals that can be used for the first metal foil include aluminum, copper, SUS, and nickel. The first metal foil may be an aluminum foil. The thickness of the first metal foil is, for example, not less than 0.1 μm and not more than 100 μm.

[0021] (2nd process) The second step is a step of laminating a second metal foil onto the surface of the first metal foil on which the adhesive has been applied, and then heating and pressing the resulting laminated foil.

[0022] The method of heating and pressing in the second step is not particularly limited, and for example, a workpiece in which a roll of a second metal foil is unrolled and bonded onto the surface of a first metal foil to which an adhesive has been applied may be heated and pressed using a heat roll, a rubber roll, or the like. The hot roll temperature may be, for example, 90° C. or higher. The hot roll nip pressure may be, for example, 0.45 MPa or more.

[0023] The metal used for the second metal foil may be different from the metal used for the first metal foil. Metals that can be used for the second metal foil include copper, SUS, nickel, and the like. For example, aluminum may be selected as the metal for the first metal foil, and copper may be selected as the metal for the second metal foil. The second metal foil may be a copper foil. The thickness of the second metal foil is, for example, not less than 0.1 μm and not more than 100 μm.

[0024] (3rd step) The third step is a step of winding up the laminated foil and heating it. In the third step, the take-up tension of the laminated foil is 316 N / m or more. In the third step, the laminated foil may be wound up so that a pressure of 1.6 kPa or more is applied thereto. In the third step, the heating temperature of the laminated foil may be equal to or higher than the melting point of the main agent of the adhesive. The heating time for the laminated foil in the third step is not particularly limited, and may be, for example, 3 days or more. The method for winding the laminated foil is not particularly limited, and the laminated foil obtained in the second step may be wound using a roller, etc. After winding the laminated foil, the laminated foil in the roll state is heated at a temperature equal to or higher than the melting point of the main agent of the adhesive. The winding line speed may be, for example, 15 m / min or more.

[0025] The current collector foil obtained by the manufacturing method of the present disclosure comprises a laminated foil in which a first metal foil and a second metal foil are laminated with an adhesive. The current collector foil may be a bipolar current collector foil. A bipolar current collector foil is a current collector foil having a positive current collector foil on one side and a negative current collector foil on the other side. The first metal foil is a positive current collector foil, and the second metal foil is a negative current collector foil. The thickness of the current collecting foil is, for example, not less than 0.2 μm and not more than 200 μm.

[0026] The present disclosure provides a method for producing a battery that uses a current collector foil obtained by the method for producing a current collector foil. The current collector foil of the present disclosure is used in the manufacture of batteries. The type of battery in which the current collecting foil is used is not particularly limited, and may be, for example, a lithium ion secondary battery. The battery may be a liquid battery using an electrolytic solution as an electrolyte, or a solid battery using a solid electrolyte as an electrolyte. Applications of the battery include, for example, power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline automobiles, and diesel automobiles. In particular, the battery may be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery may also be used as a power source for moving objects other than vehicles (for example, railways, ships, and aircraft), and may be used as a power source for electrical appliances such as information processing devices. EXAMPLES

[0027] Example 1 An aluminum foil was used as the first metal foil, and a copper foil was used as the second metal foil. The adhesive used a polyolefin resin (Mitsui Chemicals, Inc., Unistall XP11B, melting point: 80° C.) as a base agent, Ni-plated particles as a conductive assistant, and an epoxy resin as a curing agent. FIG. 1 is a schematic diagram showing an example of a bonding apparatus (dry lamination). The dry lamination conditions shown in FIG. 1 were set as follows: Line speed: 15m / min Gravure roll: Elongated, 75 lines ·Drying oven temperature: 150℃ Heat roll temperature: 90℃ Heat roll nip pressure: 0.45MPa In Example 1, as shown in FIG. 1 , in the first step, a first metal foil 1 is unwound, an adhesive 2 is applied to one side of the first metal foil 1 using a gravure roll 3, and the adhesive 2 is dried in a drying furnace 4. In the second step, a second metal foil 5 is unwound and placed on the side of the first metal foil 1 on which the adhesive 2 is applied, and these are bonded together while being heated and pressed using a heat roll 6 and a rubber roll 7. In the third step, a bonded foil 8 is wound up so that the winding tension is 316 N / m. Thereafter, as an aging treatment, the bonded foil 8 is given a thermal history of 80° C. for 3 days while still in the wound roll state, to obtain a current collector foil.

[0028] Example 2 In Example 2, a current collector foil was obtained in the same manner as in Example 1, except that in the third step, the laminated foil 8 was wound up so that the winding tension was 474 N / m.

[0029] Comparative Example 1 In Comparative Example 1, a current collector foil was obtained in the same manner as in Example 1, except that in the third step, the laminated foil 8 was wound up so that the winding tension was 158 N / m.

[0030] FIG. 2 is a graph showing the results of CAE calculations of compressive stress acting on the laminated foil during winding of the laminated foil versus the radial position from the center of the roll in the third step of Examples 1 and 2 and Comparative Example 1. The calculation software used was Wind Master, manufactured by SUNAMI Corporation. Table 1 also shows the winding tension in the third step in Examples 1 and 2 and Comparative Example 1, the average compressive stress (pressure) calculated from FIG. 2, and the results of an evaluation of whether or not the current collecting foils produced in Examples 1 and 2 and Comparative Example 1 contained pinholes. As shown in Figure 2, the compressive stress decreases the further away from the center of the roll. However, as shown in Table 1, when the winding tension is 316 N / m or more and it is ensured that the minimum compressive stress applied to the laminated foil is 1.6 kPa or more, sufficient pressure is applied to the entire laminated foil, and the laminated foil is heated to above the melting point of the main adhesive, causing the adhesive to flow and filling pinholes in the resulting current collecting foil with adhesive. As a result, the current collecting foil is evaluated as being pinhole-free.

[0031] [Table 1]

[0032] As shown in Table 1, it has been demonstrated that the current collecting foil obtained by the manufacturing method of the present disclosure can reduce the occurrence of pinholes. [Explanation of symbols]

[0033] 1. First metal foil 2. Glue 3. Gravure roll 4.Drying oven 5. Second metal foil 6. Heat roll 7. Rubber roll 8. Laminated foil

Claims

1. A first step of applying an adhesive to one side of a first metal foil; A second step of laminating a second metal foil onto the surface of the first metal foil on which the adhesive is applied, and then heating and pressing the second metal foil to obtain a laminated foil; A third step of winding and heating the laminated foil, In the third step, the winding tension of the laminated foil is 316 N / m or more, In the third step, the heating temperature of the laminated foil is equal to or higher than the melting point of the main agent of the adhesive.

2. The method for producing a current collector foil according to claim 1 , wherein in the third step, the laminated foil is wound up so that a pressure of 1.6 kPa or more is applied thereto.

3. The method for producing a current collector foil according to claim 1 , wherein the base material of the adhesive is a polyolefin resin.

4. A method for producing a battery using a current collecting foil obtained by the method according to any one of claims 1 to 3.

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