Battery manufacturing method

Abstract

To provide a method for manufacturing a battery, with which a separator and a resin member can be welded favorably.SOLUTION: The present disclosure provides a method for manufacturing a battery. The method includes: a first step of preparing a first member including a current collector, a mixture layer disposed at least one face of the current collector in a thickness direction, and a resin member covering the outer edge of the current collector; a second step of obtaining a second member in which a separator is disposed on the first member in the thickness direction; and a third step of obtaining an electrode laminate by using the second member. The second step includes: heat treatment of heating the resin member with laser while transporting the first member in a first direction; and thermal welding treatment of pressing the separator against the heated resin member to thermally weld the resin member and the separator, while transporting the first member in the first direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] This disclosure relates to a method for manufacturing a battery. [Background technology]

[0002] Information-related devices and communication equipment such as personal computers, video cameras, and mobile phones are widespread. Furthermore, from the perspective of reducing the environmental impact, motor-driven vehicles such as electric vehicles are becoming more common. Consequently, various studies are being conducted regarding the batteries used as power sources for these devices.

[0003] For example, Patent Document 1 discloses a method for manufacturing an electrode unit including an electrode, a resin frame, and a separator, wherein the separator is welded to the resin frame. Patent Document 2 also discloses a method for manufacturing an energy storage device, wherein a pair of separators are welded to at least two diagonal corners of the four corners of one of the electrodes. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-107485 [Patent Document 2] Japanese Patent Publication No. 2016-038955 [Overview of the project] [Problems that the invention aims to solve]

[0005] In battery manufacturing, it is known that a separator is laminated onto a component having a current collector, an asphalt layer, and a resin component by heat welding the resin component to the separator. However, if the welding of the separator is insufficient, the separator may not function properly in the battery, which could lead to short circuits and other problems.

[0006] This disclosure has been made in view of the above circumstances, and its main purpose is to provide a method for manufacturing a battery that can successfully weld a separator and a resin component together. [Means for solving the problem]

[0007] [1] A method for manufacturing a battery, comprising: a first step of preparing a first member having a current collector, a composite material layer disposed on at least one surface of the current collector in the thickness direction, and a resin member covering the outer edge of the current collector; a second step of obtaining a second member having a separator disposed on the first member in the thickness direction; and a third step of obtaining an electrode laminate using the second member, wherein the second step comprises a heat treatment in which the resin member is heated by a laser while the first member is transported in a first direction, and a heat welding treatment in which the separator is pressed against the heated resin member while the first member is transported in a first direction, thereby heat welding the resin member and the separator together.

[0008] [2] The method for manufacturing a battery according to [1], wherein the laser is a CO2 laser.

[0009] [3] A method for manufacturing a battery according to [1] or [2], wherein the resin member extending in the first direction is heated during the heat treatment described above.

[0010] [4] A method for manufacturing a battery according to any one of [1] to [3], wherein the planar shape of the first member is rectangular, and the first direction is the direction in which the longer side of the rectangle extends.

[0011] [5] A method for manufacturing a battery according to any one of [1] to [4], wherein the time from heating to pressing is 1 second or less. [Brief explanation of the drawing]

[0012] [Figure 1]These are schematic plan views and schematic cross-sectional views illustrating the first member prepared in the first step of this disclosure. [Figure 2] These are schematic plan views, schematic side views, and schematic cross-sectional views illustrating the second step in this disclosure. [Figure 3] These are exploded views and schematic cross-sectional views illustrating the third step in this disclosure. [Figure 4] This figure illustrates the issues in this disclosure. [Modes for carrying out the invention]

[0013] The battery manufacturing method described below will be explained in detail with reference to the drawings. The following figures are schematic representations, and the size and shape of each part have been exaggerated as appropriate for ease of understanding.

[0014] Figure 1 is a schematic plan view and schematic cross-sectional view illustrating the first member prepared in the first step of this disclosure. Specifically, Figures 1(a) and (c) are schematic plan views of the first member, and Figure 1(b) is a cross-sectional view AA of Figure 1(a). Figure 1(c) will be described later. First, in the battery manufacturing method of this disclosure, as shown in Figures 1(a) and (b), in the first step, a current collector 1 and a thickness direction D T A first member 10 is prepared, which has a composite material layer 2 (2A, 2B) arranged on at least one surface (p, q) of the current collector 1, and a resin member 3 that covers the outer edge O of the current collector 1.

[0015] FIG. 2 is a schematic plan view, a schematic side view, and a schematic cross-sectional view illustrating the second step in the present disclosure. Specifically, FIG. 2(a) is a schematic plan view of the second step viewed from the thickness direction, FIG. 2(b) is a schematic side view of FIG. 2(a) viewed from a direction orthogonal to the thickness direction (from the bottom of the paper surface toward the paper surface), and FIG. 2(c) is a schematic cross-sectional view of the second member obtained in the second step. In FIG. 2(b), the first member other than the resin member is omitted. Also, FIG. 2(b) is appropriately enlarged with respect to FIG. 2(a). As shown in FIGS. 2(a) and (b), in the second step, while the first member 10 is being conveyed in the first direction D1, the resin member 3 is heated by the laser L (heat treatment). In FIGS. 2(a) and (b), the laser L is irradiated from the laser head LH toward the resin member 3. Then, while the first member 10 is being conveyed in the first direction D1, the separator 11 is pressed against the heated resin member 3, and the resin member 3 and the separator 11 are heat-welded (heat welding process). In FIGS. 2(a) and (b), the separator 11 is fed out from the roll R and disposed on the first member, and is pressed by the pressing mechanism P. As a result, as shown in FIG. 2(c), in the thickness direction D T a second member 20 in which the separator 11 is disposed on the first member 10 is obtained.

[0016] Then, as shown in FIG. 3, an electrode laminate 100 is obtained using the second member 20 (20A, 20B, 20C) (third step). Details of the third step will be described later.

[0017] According to the present disclosure, by having the second step include a predetermined heat treatment and a heat welding process, the separator and the resin member can be favorably welded.

[0018] As described above, it is known that separators are heat-welded to resin members to create a laminate of separators. However, there is room for improvement in the welding method. For example, as shown in Figures 4(a) and (b), it is assumed that a separator 11 is placed and fixed on a first member 10 having a current collector 1, an asphalt layer 2, and a resin member 3, and then a hot iron 200 is pressed against it. In other words, it is assumed that the separator and the resin member are heated simultaneously to heat-weld them. On the other hand, since separators are generally thin, it is difficult to control the heat input balance. For example, if the heat source input is insufficient, it is difficult to sufficiently weld the separator and the resin member. Also, for example, if the heat source input is excessive, the separator may be damaged and its function may be impaired. In contrast, in the battery manufacturing method of this disclosure, as shown in Figures 2(a) and (b), the resin member and the separator are heat-welded by pressing the separator against the resin member heated by a laser. In other words, only the resin member is heated by the laser. Therefore, it becomes easier to control the heat input balance, and the separator and resin component can be heat-welded well while suppressing damage to the separator.

[0019] Furthermore, as shown in Figures 2(a) and (b), the separator 11 can also be fed out from the feed roll R while tension is applied. This makes it possible to suppress the occurrence of wrinkles in the separator when pressed.

[0020] 1.First step The first step is the step of preparing a predetermined first component.

[0021] As shown in Figures 1(a) and (b), the first member 10 is a current collector 1 and has a thickness direction D T The current collector 1 comprises a composite material layer 2 disposed on at least one surface (p, q) of the current collector 1, and a resin member 3 covering the outer edge O of the current collector 1.

[0022] The current collector may function as a positive electrode current collector, a negative electrode current collector, or both. In other words, the first component may be a positive electrode component, a negative electrode component, or a bipolar component. Examples of materials for the current collector include metals such as aluminum, copper, stainless steel, and nickel. Examples of shapes for the current collector include foil and mesh.

[0023] As shown in Figure 1(b), the composite layer 2 (2A, 2B) is in the thickness direction D T In this case, the composite material layers may be arranged on both sides (p, q) of the current collector 1. In this case, it is preferable that one of the composite material layers 2A and 2B is the positive electrode composite material layer (positive electrode active material layer) and the other is the negative electrode composite material layer (negative electrode active material layer). On the other hand, the composite material layers may be arranged on only one side of the current collector.

[0024] The composite layer contains at least an active material and, if necessary, at least one of a conductive additive and a binder.

[0025] When the composite layer is the positive electrode active material layer, the active material (positive electrode active material) can be, for example, an oxide active material. An example of an oxide active material is LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Examples of active materials include rock salt layered types such as O2, spinel-type active materials such as LiMn2O4, and olivine-type active materials such as LiFePO4. Sulfur (S) may also be used as the positive electrode active material. The shape of the positive electrode active material is, for example, particulate.

[0026] When the composite layer is the negative electrode active material layer, examples of active materials (negative electrode active materials) include Li-based active materials such as metallic lithium and lithium alloys; carbon-based active materials such as graphite, hard carbon, and soft carbon; oxide-based active materials such as lithium titanate; and Si-based active materials such as elemental Si, Si alloys, and Si oxides.

[0027] Examples of conductive additives include carbon materials. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and Ketjenblack (KB), and fibrous carbon materials such as carbon fibers, carbon nanotubes (CNTs), and carbon nanofibers (CNFs). Examples of binders include rubber-based binders such as butadiene rubber (BR), and fluorine-containing binders such as polyvinylidene fluoride (PVDF). The thickness of the composite layer is, for example, 0.1 μm or more and 1000 μm or less.

[0028] The resin member covers the outer edge of the current collector. Typically, in the first member, the entire circumference of the outer edge of the current collector is covered with the resin member. Also, as shown in Figure 1, typically the outer edge of the resin member is located outside the outer edge O of the current collector 1, and the inner edge of the resin member is located inside the outer edge O of the current collector 1. In addition, typically, the resin member is positioned with a gap between its inner edge and the outer edge of the composite layer.

[0029] Thermoplastic resins are preferred as the resin component. Examples of thermoplastic resins include fluororesins such as polytetrafluoroethylene (PTFE), polyethylene (PE), and olefin resins such as polypropylene.

[0030] As shown in Figure 1, the planar shape of the first member is preferably rectangular. The lengths of each side constituting the rectangle are not particularly limited, but the length of the shorter side is, for example, 20 cm or more and 100 cm or less, and the length of the longer side is, for example, 50 cm or more and 200 cm or less.

[0031] In the first step, one first member may be prepared, or multiple first members may be prepared. In the latter case, as shown in Figure 1(c), the multiple first members (10A, 10B) may be crosslinked by the resin member 3 in the direction of extension of their long sides (left-right direction of the paper).

[0032] 2.Second process The second step is to obtain a second member having undergone a predetermined heat treatment and heat welding treatment, wherein a separator is arranged on the first member in the thickness direction. In the second member, the composite material layer may be arranged on both sides of the current collector in the thickness direction, or on one side. In the former case, as shown in Figure 2(c), the separator 11 is usually arranged on the surface of one of the composite material layers (2A).

[0033] The material for the separator is not particularly limited as long as it is a porous membrane; for example, a resin such as polyethylene (PE) can be used. The thickness of the separator is, for example, 0.1 μm or more and 1000 μm or less.

[0034] (1) Heat treatment The heat treatment is a process in which the resin member is heated by a laser while the first member is transported in a first direction. The first direction is preferably the direction in which the long side extends as described above.

[0035] The type of laser is not particularly limited, but examples include solid-state lasers such as YAG lasers and gaseous lasers such as CO2 lasers. Among these, CO2 lasers are preferred.

[0036] The laser irradiation conditions, such as the laser wavelength, beam diameter, and power output, are not particularly limited as long as the resin component is heated above its melting point, and can be adjusted as appropriate. For example, the laser wavelength is 9 μm or more and 11 μm or less. The beam diameter (Φ) is 1 mm or more and 10 mm or less. The laser power output is 100 W or more and 150 W or less.

[0037] As shown in Figures 2(a) and (b), the laser head LH is typically installed upstream in the transport direction relative to the roll R and pressurizing mechanism P, which will be described later.

[0038] In the heat treatment, it is preferable to heat the resin member extending in the first direction. In other words, in the second step, it is preferable to heat-weld the resin member and the separator at the outer edge of the first member extending in the first direction. The resin member extending in the first direction can be considered, for example, the portion of the resin member that constitutes the long side when the planar shape of the first member is the rectangle described above.

[0039] (2) Heat welding treatment The heat welding process involves pressing the separator against the heated resin member while conveying the first member in the first direction, thereby heat welding the resin member and the separator together.

[0040] The pressing method is not particularly limited, and as shown in Figure 2, a method using a pressurizing mechanism such as an elastic roll can be cited. The applied pressure is not particularly limited as long as the resin member and the separator can be heat-welded together, and can be adjusted as appropriate.

[0041] It is preferable that the time from heating to pressing is 1 second or less. The above time may be 500 msec or less, 100 msec or less, or 10 msec or less. On the other hand, the above time is, for example, 5 msec or more. By setting the time as described above, the heat welding can be made stronger. Here, "time from heating to pressing" can be understood as the time from when the resin member 10 passes the edge α of the laser irradiation area (the downstream edge in the transport direction) to when it reaches the part β where pressing is applied (the part that overlaps with the pressurizing mechanism P in the thickness direction), as shown in Figure 2(b). It is preferable that the transport speed in the heating treatment and heat welding treatment be a speed that obtains the above time. The transport speed is, for example, 200 mm / s or more and 300 mm / s or less.

[0042] (3) Other processing The second step may include, for example, a single-sheet process in which, if multiple first members are crosslinked with a resin member as shown in Figure 1(c), the resin member at the crosslinked portion is cut after the heat welding process to obtain individual second members.

[0043] 3. Third Process The lamination process is a process of obtaining an electrode laminate using the above-described second member. The electrode laminate is a laminate in which a plurality of electrodes are laminated in the thickness direction.

[0044] FIG. 3(a) is an exploded view illustrating the lamination process, and FIG. 3(b) is a schematic cross-sectional view illustrating the electrode laminate obtained in the lamination process. In the lamination process, as shown in FIG. 3(a), a plurality of second members (20A to 20C) produced in the above-described second process and one first member 10 are laminated via a spacer 30 and a sheath 40. The material of the spacer can be the same as that of the resin member.

[0045] As shown in FIGS. 3(a) and (b), the second member 20A has a current collector 1, a composite layer 2A (positive electrode active material layer), and a separator 11 in this order in the thickness direction D T and functions as a positive electrode terminal electrode (CA) in the electrode laminate. Also, the second members 20B and 20C each have a composite layer 2B (negative electrode active material layer), a current collector 1, a composite layer 2A (positive electrode active material layer), and a separator 11 in this order in the thickness direction D T and function as bipolar electrodes (BP). Also, the first member 10 has a current collector 1 and a composite layer 2B (negative electrode active material layer) in the thickness direction D T and functions as a negative electrode terminal electrode (NA).

[0046] After lamination, a liquid injection port (not shown) is formed by pulling out the sheath 40, and an electrolytic solution 50 is injected through the liquid injection port. Then, by sealing the liquid injection port, an electrode laminate 100 filled with the electrolytic solution 50 as shown in FIG. 3(b) is obtained. Examples of the electrolytic solution include conventionally known electrolytic solutions that can be used in lithium ion batteries. Also, a battery is obtained by housing the electrode laminate in an exterior body. Examples of the exterior body include a laminate exterior body.

[0047] 4. Battery The battery in this disclosure is typically a lithium-ion battery. Furthermore, the battery in this disclosure is typically a liquid-based battery (non-aqueous battery) that uses an electrolyte solution. Applications of the battery include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. It is particularly preferable that the battery be used as a 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 other mobile devices (e.g., trains, ships, aircraft), or as a power source for electrical products such as information processing devices.

[0048] This disclosure is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of this disclosure and achieves similar effects is included within the technical scope of this disclosure. [Explanation of symbols]

[0049] 1 ... Current collector 2…Mixture layer 3 ... Resin component 10…First component 11... Separator 20...Second component 100… Electrode stack O...outer edge

Claims

1. A first step is to prepare a first member having a current collector, a composite material layer disposed on at least one surface of the current collector in the thickness direction, and a resin member covering the outer edge of the current collector. A second step is to obtain a second member in which a separator is arranged on the first member in the thickness direction, The process includes a third step of obtaining an electrode laminate using the second member, The second step is, A heat treatment is performed in which the resin member is heated by a laser while the first member is being transported in a first direction, A method for manufacturing a battery, comprising: a heat welding process in which, while conveying the first member in a first direction, the separator is pressed against the heated resin member to heat-weld the resin member and the separator together.

2. The laser is CO ２ A method for manufacturing a battery according to claim 1, wherein the laser is used.

3. The method for manufacturing a battery according to claim 1, wherein in the heat treatment, the resin member extending in the first direction is heated.

4. The planar shape of the first member is rectangular. The method for manufacturing a battery according to claim 1, wherein the first direction is the direction in which the longer side of the rectangle extends.

5. A method for manufacturing a battery according to any one of claims 1 to 4, wherein the time from heating to pressing is 1 sec or less.

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