Method for manufacturing electrode

Abstract

To provide a manufacturing method of an electrode capable of suppressing deformation or breakage of a current collector foil in an uncoated part.SOLUTION: The method of manufacturing an electrode includes a pressing step of roll-pressing the precursor sheet 200 using the upper roll 10 and the lower roll 13. A spacer 19 is provided between a main axle box 11 that rotatably supports an axle 10a portion of the upper roll 10 and a main axle box 14 that rotatably supports an axle 13a portion of the lower roll 13. The spacer 19 has a first structure in which the spacer 19 is arranged on the side of the upper roll 10 and the lower roll 13 with respect to the main axle box 11,14. The pressing step includes a step of bending the upper roll 10 and the lower roll 13 outward by bringing the main axle box 11,14 into contact with the spacer 19 when the uncoated part 240 passes between the upper roll 10 and the lower roll 13.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing an electrode. [Background technology]

[0002] Japanese Patent Application Laid-Open Publication No. 2023-94978 (Patent Document 1) discloses a method for manufacturing an electrode, which includes a preparation step of preparing a precursor sheet having a current collecting foil and a coated portion and an uncoated portion arranged on the current collecting foil, and a coated portion pressing step of roll-pressing the coated portion in the thickness direction using a pair of rolls. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-94978 Summary of the Invention [Problem to be solved by the invention]

[0004] In the coated portion pressing step, when the uncoated portion passes between a pair of rolls, the rolls may come into contact with the current collector foil, causing deformation or breakage of the current collector foil.

[0005] The present disclosure has been made to solve the above-mentioned problems, and its purpose is to provide a method for manufacturing an electrode that can suppress deformation or breakage of the current collecting foil in uncoated areas. [Means for solving the problem]

[0006] A method for manufacturing an electrode according to one aspect of the present disclosure includes a preparation step of partially coating a current collector foil with an electrode material to prepare a precursor sheet having a coated portion and an uncoated portion, and a press step of roll-pressing the precursor sheet using a first roll and a second roll. A spacer is provided between a main axle box that rotatably supports a first shaft of the first roll and a main axle box that rotatably supports a second shaft of the second roll. The spacer has at least one of a first structure that is disposed on the first roll and second roll side of the main axle box, and a second structure that has a tapered shape that widens toward the first roll and second roll side in a cross section taken along a plane including the first shaft and the second shaft. The press step includes a step of contacting the main axle boxes of the first roll and the second roll with the spacer when the uncoated portion passes between the first roll and the second roll, thereby curving the first roll and the second roll outward.

[0007] According to the present disclosure, the distance between the center of the first roll and the center of the second roll is longer than the distance between the end of the first roll and the end of the second roll, which prevents the center of the first roll or the second roll from coming into contact with the uncoated portion, thereby suppressing deformation or breakage of the uncoated portion. [Effects of the Invention]

[0008] According to the method for manufacturing an electrode of the present disclosure, deformation or breakage of the current collector foil in the uncoated portion is suppressed. [Brief explanation of the drawings]

[0009] [Figure 1] 1A to 1C are diagrams showing a flow of a method for manufacturing an electrode according to an embodiment. [Figure 2] 2 is a cross-sectional view showing the configuration of a press machine used in the press step S2 shown in FIG. 1. [Figure 3] FIG. 1 is a diagram showing a press machine provided with a spacer having a first structure. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference numerals, and description thereof will not be repeated.

[0011] The electrode manufactured by the manufacturing method according to this embodiment is applied to an electric storage device used as a battery for a vehicle such as a hybrid vehicle or an electric vehicle. The electrode manufactured by the manufacturing method according to this embodiment is, for example, a bipolar electrode. The electrode manufactured by the manufacturing method according to this embodiment may be a positive electrode or a negative electrode.

[0012] Fig. 1 is a diagram showing the flow of a method for manufacturing an electrode according to an embodiment. As shown in Fig. 1, the method for manufacturing an electrode includes a preparation step S1 in which an electrode material 220 is partially coated on a current collector foil 210 to prepare a precursor sheet 200 having a coated portion 230 and an uncoated portion 240. The precursor sheet 200 is strip-shaped.

[0013] The current collector foil 210 is used as a current collector for a battery. The current collector foil 210 may be either a positive electrode current collector or a negative electrode current collector. When the current collector foil 210 is used as a positive electrode current collector, examples of the material for the current collector foil 210 include Al, SUS, and Ni. When the current collector foil 210 is used as a negative electrode current collector, examples of the material for the current collector foil 210 include Cu, SUS, and Ni. The current collector foil 210 is strip-shaped.

[0014] The electrode material 220 includes at least an active material and may further include at least one of a solid electrolyte, a conductive material, and a binder.

[0015] When manufacturing a positive electrode, the active material is a positive electrode active material. As the positive electrode active material, a lithium ion composite metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, a polyanion compound, or the like that can be used as a positive electrode active material for a lithium ion secondary battery can be used. Two or more positive electrode active materials may also be used in combination. For example, the positive electrode active material may contain olivine-type lithium iron phosphate (LiFePO4).

[0016] When a negative electrode is produced, the active material is a negative electrode active material, which may be lithium, carbon, a metal compound, or an element or compound thereof that can be alloyed with lithium.

[0017] The coated sections 230 are sections of the current collector foil 210 that are coated with the electrode material 220. The uncoated sections 240 are sections of the current collector foil 210 that are not coated with the electrode material 220. The coated sections 230 and the uncoated sections 240 are arranged alternately along the longitudinal direction of the current collector foil 210.

[0018] The precursor sheet 200 is prepared, for example, by applying an electrode material 220 containing a dispersion medium to a current collector foil 210 and drying the applied material. The method for applying the electrode material is not particularly limited, and any common coating method can be used. The drying temperature is also not particularly limited as long as it is a temperature at which the dispersion medium volatilizes.

[0019] The electrode manufacturing method further includes a pressing step S2 in which the precursor sheet 200 is roll-pressed using an upper roll 10 and a lower roll 13. The upper roll 10 is an example of a "first roll" in the present disclosure. The lower roll 13 is an example of a "second roll" in the present disclosure. The upper roll 10 and the lower roll 13 are arranged to face each other. The precursor sheet 200 is transported between the upper roll 10 and the lower roll 13 along the longitudinal direction.

[0020] Fig. 2 is a cross-sectional view showing the configuration of a press machine used in the press step S2 shown in Fig. 1. As shown in Fig. 2, the press machine 100 includes an upper roll 10, a lower roll 13, main chocks 11 and 14, bend chocks 12 and 15, a lifting mechanism 16, a load cell 17, a bend cylinder 18, and a frame 20.

[0021] The frame 20 accommodates the upper roll 10, the lower roll 13, the main axle boxes 11 and 14, the bend axle boxes 12 and 15, the lifting mechanism 16, the load cell 17, and the bend cylinder 18. Within the frame 20, the upper roll 10 is disposed above the lower roll 13.

[0022] A pair of main axle boxes 11 are arranged at both ends of the upper roll 10 and rotatably support the shaft 10a of the upper roll 10. The pair of main axle boxes 11 are fixed to the upper surface of the frame 20, and a pair of bend axle boxes 12 are arranged on both outer sides of the pair of main axle boxes 11 and rotatably support the shaft 10a of the upper roll 10. The shaft 10a is an example of the "first shaft" in the present disclosure.

[0023] The pair of main axle boxes 14 are disposed on both ends of the lower roll 13 and rotatably support the shaft 13a of the lower roll 13. The pair of bend axle boxes 15 are disposed on both outer sides of the pair of main axle boxes 14 and rotatably support the shaft 13a of the lower roll 13. The shaft 13a is an example of the "second shaft" of the present disclosure.

[0024] The lifting mechanism 16 moves the pair of main axle boxes 14 upward. The load cell 17 measures the load (hereinafter referred to as "press load") that the pair of main axle boxes 14 receive from the lifting mechanism 16.

[0025] The bend cylinder 18 is attached to the bend axle box 12 and the bend axle box 15, and applies a load (hereinafter referred to as "bend load") in a direction that moves the bend axle box 12 and the bend axle box 15 apart.

[0026] A precursor sheet 200 is transported between the upper roll 10 and the lower roll 13. While the precursor sheet 200 passes between the upper roll 10 and the lower roll 13, the press machine 100 controls the lifting mechanism 16 so that the press load measured by the load cell 17 falls within a desired range.

[0027] 2 shows the press 100 when the coating unit 230 passes between the upper roll 10 and the lower roll 13. When the coating unit 230 passes between the upper roll 10 and the lower roll 13, the press 100 preferably applies a uniform load to the entire coating unit 230. In order to apply a uniform load to the entire coating unit 230, the upper roll 10 and the lower roll 13 are preferably flat and not bent. Therefore, the bend load is adjusted in advance so that the upper roll 10 and the lower roll 13 do not bend (are flat) when the coating unit 230 passes between the upper roll 10 and the lower roll 13.

[0028] As described above, the precursor sheet 200 has a coated portion 230 and an uncoated portion 240. When the uncoated portion 240 passes between the upper roll 10 and the lower roll 13, if the upper roll 10 comes into contact with the uncoated portion 240, the uncoated portion 240 (i.e., the current collector foil 210) may be deformed or broken. To prevent the uncoated portion 240 from being deformed or broken, the press machine 100 according to this embodiment has a spacer 19 between the main axle box 11 and the main axle box 14. That is, the spacer 19 is disposed above the main axle box 14 for the lower roll 13.

[0029] The height of the spacer 19 is set so that the main chock 11 does not come into contact with the spacer 19 when the coated portion 230 passes between the upper roll 10 and the lower roll 13, and so that the main chock 11 comes into contact with the spacer 19 when the uncoated portion 240 passes between the upper roll 10 and the lower roll 13. Furthermore, the height of the spacer 19 is set so that when the uncoated portion 240 passes between the upper roll 10 and the lower roll 13, the separation distance between the upper roll 10 and the lower roll 13, assuming that the bending load is 0, is longer than the thickness of the current collecting foil 210.

[0030] As described above, the bending load is adjusted so that the upper roll 10 and the lower roll 13 do not bend (so that they remain flat) when the coated portion 230 passes between the upper roll 10 and the lower roll 13. Therefore, when the uncoated portion 240 passes between the upper roll 10 and the lower roll 13, the upper roll 10 does not receive a reaction force from the electrode material 220, and the upper roll 10 and the lower roll 13 are curved inward by the bending load. In other words, the distance between the center of the upper roll 10 and the center of the lower roll 13 is shorter than the distance between the end of the upper roll 10 and the end of the lower roll 13. As a result, even if a spacer 19 is provided between the main chock 11 and the main chock 14, the center of the upper roll 10 may come into contact with the uncoated portion 240, causing the uncoated portion 240 to deform or break.

[0031] Therefore, in order to further suppress deformation or breakage of the uncoated portion 240, the spacer 19 has a first structure in which it is arranged on the upper roll 10 and lower roll 13 side with respect to the main chocks 11, 14.

[0032] FIG. 3 is a diagram showing a press equipped with a spacer having the first structure. FIG. 3 shows the main components of the press 100 when the uncoated portion 240 passes between the upper roll 10 and the lower roll 13. Because the spacer 19 is positioned on the upper roll 10 and lower roll 13 sides of the main chocks 11 and 14, the force points on the shafts 10a and 13a where the press load is applied are located on both sides outside the fulcrums corresponding to the spacer 19. As a result, as shown in FIG. 3, when the uncoated portion 240 passes between the upper roll 10 and the lower roll 13, the upper roll 10 and the lower roll 13 bend outward. In other words, the distance between the center of the upper roll 10 and the center of the lower roll 13 is longer than the distance between the end of the upper roll 10 and the end of the lower roll 13. This prevents the center of the upper roll 10 from coming into contact with the uncoated portion 240, thereby preventing deformation or breakage of the uncoated portion 240.

[0033] Instead of or in addition to the first structure, the spacer 19 may have a second structure having a tapered shape that widens toward the upper roll 10 and the lower roll 13 in a cross section taken along a plane including the shafts 10a, 13a. When the spacer 19 has the second structure, the press load also acts to curve the upper roll 10 and the lower roll 13 outward relative to the shafts 10a, 13a. This prevents the center of the upper roll 10 from coming into contact with the uncoated portion 240, and suppresses deformation or breakage of the uncoated portion 240.

[0034] It is preferable that the spacer 19 has both the first structure and the second structure, which further prevents the center of the upper roll 10 from contacting the uncoated portion 240.

[0035] When the spacer 19 has only the first structure, the spacer 19 has a rectangular shape in a cross section cut along a plane including the axes 10a and 13a.

[0036] As described above, the method for manufacturing an electrode according to this embodiment includes a preparation step S1 in which electrode material 220 is partially coated on a current collector foil 210 to prepare a precursor sheet 200 having a coated portion 230 and an uncoated portion 240, and a pressing step S2 in which the precursor sheet 200 is roll-pressed using the upper roll 10 and the lower roll 13. A spacer 19 is provided between the main axle box 11 that rotatably supports the shaft 10a of the upper roll 10 and the main axle box 14 that rotatably supports the shaft 13a of the lower roll 13. The spacer 19 has at least one of a first structure that is disposed on the upper roll 10 and lower roll 13 side with respect to the main axle boxes 11 and 14, and a second structure that has a tapered shape that widens toward the upper roll 10 and lower roll 13 in a cross section taken along a plane including the shafts 10a and 13a. The pressing step S2 includes a step of bending the upper roll 10 and the lower roll 13 outward by bringing the main chocks 11, 14 into contact with the spacer 19 when the uncoated portion 240 passes between the upper roll 10 and the lower roll 13. This prevents the uncoated portion 240 from being deformed or broken.

[0037] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is defined by the claims, not by the description of the above embodiments, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0038] 10 upper roll, 10a, 13a shafts, 11, 14 main axle boxes, 12, 15 bend axle boxes, 13 lower roll, 16 lifting mechanism, 17 load cell, 18 bend cylinder, 19 spacer, 20 frame, 100 press machine, 200 precursor sheet, 210 current collecting foil, 220 electrode material, 230 coated section, 240 uncoated section.

Claims

[Claim 1] A method for manufacturing an electrode, comprising: a preparation step of partially coating an electrode material on a current collecting foil to prepare a precursor sheet having a coated portion and an uncoated portion; a pressing step of roll-pressing the precursor sheet using a first roll and a second roll, a spacer is provided between a main axle box that rotatably supports a first shaft of the first roll and a main axle box that rotatably supports a second shaft of the second roll, the spacer has at least one of a first structure disposed on the first roll and second roll side with respect to the main chock, and a second structure having a tapered shape expanding toward the first roll and second roll side in a cross section taken along a plane including the first axis and the second axis, the pressing step includes a step of contacting the main chocks of the first roll and the second roll with the spacer when the uncoated portion passes between the first roll and the second roll, thereby curving the first roll and the second roll outward.

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