Electrode manufacturing method

Abstract

To provide an electrode manufacturing method capable of preventing the electrode from peeling off from the current collecting foil.SOLUTION: The electrode manufacturing method includes: a coating step of obtaining a coating by dispersing the electrode material in a solvent and applying the resulting slurry over the current collecting foil; and a drying step of drying the coating while the current collecting foil on which the coating is formed is transported inside the drying oven. The coating has three regions divided along the transport direction, including a central portion disposed at the center in the width direction and edges on both sides of the central portion. In the drying step, each edge of the coating is dried with a low-energy-density heat source, and the center of the coating is dried by a high-energy-density heat source.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, a method for manufacturing an electrode has been known in which a slurry obtained by dispersing an electrode material in a solvent is applied onto a current collector foil to obtain a coating film, and then the coating film is dried in a drying furnace to obtain an electrode.

[0003] For example, Patent Document 1 discloses a method for manufacturing an electrode, in which a slurry for forming an electrode composite layer is applied to a web-shaped current collector foil, and then the current collector foil coated with the slurry is sent in one direction in a drying furnace while hot air is applied to the coating film to dry the coating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-084383 Summary of the Invention [Problem to be solved by the invention]

[0005] The coating film formed on the current collector foil becomes thinner at its edges than at its center due to dripping caused by surface tension. As a result, the edges of the coating film dry more quickly than the center. This makes the edges of the electrode more likely to peel off from the current collector foil as the coating film dries, which can lead to a decrease in battery performance.

[0006] Therefore, a main object of the present disclosure is to provide a method for manufacturing an electrode that can prevent the electrode from peeling off from the current collecting foil. [Means for solving the problem]

[0007] The present disclosure provides at least the following aspects.

[0008] The first aspect is a method for manufacturing an electrode, comprising: a coating step of coating a current collecting foil with a slurry obtained by dispersing an electrode material in a solvent to obtain a coating film; and a drying step of drying the coating film while transporting the current collecting foil with the coating film formed thereon inside a drying furnace, wherein the coating film is divided into three regions along the transport direction, having a central portion located in the center in the width direction and end portions located on either side of the central portion, and the drying step dries each end portion of the coating film with a low-energy density heat source, and dries the central portion of the coating film with a high-energy density heat source.

[0009] A second aspect is the electrode manufacturing method according to the first aspect, wherein in the drying step, the low energy density heat source is hot air or a laser, and the high energy density heat source is a laser.

[0010] A third aspect is the method for producing an electrode according to the second aspect, wherein EC / EE calculated based on the following formula is 1 or more and 4 or less, where EC is the sum of the average energy densities of the heat sources irradiated to the center part of the coating film and EE is the sum of the average energy densities of the heat sources irradiated to the edge part of the coating film. (Laser average energy density (W / cm 2 )) = (laser energy density (W / cm 2 )) ÷ (laser irradiation length in the transport direction (mm)) × (total length of drying oven in the transport direction (mm)) (Average hot air energy density (W / cm 2 )) = (Laser average energy density (W / cm 2 )) × (time (s) to dry the coating using only the laser) ÷ (time (s) to dry the coating using only hot air)

[0011] A fourth aspect is a method for producing an electrode according to any one of the first to third aspects, wherein the end of the coating film is a region extending from the outermost end of the coating film in the width direction to a widthwise inner side of 3 to 18 mm from the starting point.

[0012] A fifth aspect is the method for producing an electrode according to any one of the first to fourth aspects, wherein the length of the coating film in the width direction is 1000 mm or more and 1500 mm or less.

[0013] A method for manufacturing a battery, comprising: an electrode manufacturing step of obtaining an electrode using the electrode manufacturing method according to any one of the first to fifth aspects; and a battery manufacturing step of assembling a battery using the electrode. [Effects of the Invention]

[0014] The electrode manufacturing method of the present disclosure can prevent the electrode from peeling off from the current collecting foil, and the battery manufacturing method of the present disclosure can prevent the deterioration of battery performance due to electrode peeling. [Brief explanation of the drawings]

[0015] [Figure 1] 2 is a cross-sectional view of the drying furnace 30 taken along the transport direction X of the current collector foil 10. FIG. [Figure 2] FIG. 2 is a plan view of the coating film 20. [Figure 3] FIG. 2 is a side view of the coating film 20. [Figure 4] (A) Schematic diagram of pulsed irradiation in the transport direction X. (B) Schematic diagram of continuous irradiation in the transport direction X. [Figure 5] FIG. 1 is a schematic diagram of a heat source device 132, which is an example of the heat source device 32. [Figure 6] FIG. 2 is a schematic diagram of a heat source device 232, which is an example of the heat source device 32. [Figure 7] 10 is an experimental result showing the relationship between the edge area of ​​a coating film and the residual moisture content after drying. [Figure 8] 10 shows experimental results showing the relationship between the coating position and the drying time. [Figure 9] 1 is an experimental result showing a laser energy density map. DETAILED DESCRIPTION OF THE INVENTION

[0016] [Electrode manufacturing method] The method for manufacturing an electrode according to the present disclosure will be described using one embodiment.

[0017] The method for manufacturing an electrode in one embodiment includes a coating step in which a slurry obtained by dispersing an electrode material in a solvent is applied onto a current collector foil 10 to obtain a coating film 20, and a drying step in which the current collector foil 10 on which the coating film 20 has been formed is transported inside a drying furnace 30 to dry the coating film 20.

[0018] <Coating process> The coating step is a step in which a slurry obtained by dispersing an electrode material in a solvent is applied onto the current collector foil 10 to obtain a coating film 20. Such coating steps are well known. A typical example will be described below, but the present invention is not limited to this example.

[0019] The current collector foil 10 is not particularly limited as long as it is a sheet-like conductive material. For example, the current collector foil 10 may be a metal foil made of a metal such as stainless steel, copper, aluminum, titanium, or nickel. The metal foil may be made of an alloy containing two or more of these metals. The metal foil may also be subjected to a surface treatment such as plating. The current collector foil 10 may be made of two or more metal foils. In this case, the metal foils may be joined with an adhesive or by pressing.

[0020] The electrode material includes at least an active material. The active material can be a positive electrode active material or a negative electrode active material. The positive electrode active material is not particularly limited and may be appropriately selected from known materials depending on the desired battery performance. Examples include composite oxides, metallic lithium, and sulfur. The composite oxide composition includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum, and lithium. An example of a composite oxide is olivine-type lithium iron phosphate (LiFePO4). The negative electrode active material is not particularly limited and may be appropriately selected from known materials depending on the desired battery performance. Examples include graphite, artificial graphite, highly oriented graphite, mesocarbon microbeads, carbon such as hard carbon and soft carbon, metal compounds, elements or compounds thereof that can be alloyed with lithium, and boron-doped carbon. Examples of elements that can be alloyed with lithium include silicon and tin.

[0021] When the electrode material contains a positive electrode active material, the resulting electrode is a positive electrode. Conversely, when the electrode material contains a negative electrode material, the resulting electrode is a negative electrode.

[0022] The electrode material may optionally contain a conductive additive. The conductive additive is not particularly limited and may be appropriately selected from known materials depending on the desired battery performance. Examples include acetylene black, carbon black, and graphite.

[0023] The electrode material may optionally contain a binder. The binder is not particularly limited and may be appropriately selected from known materials depending on the desired battery performance. Examples of binders include fluorine-containing resins such as polyvinylidene fluoride, polytetrafluoroethylene, and fluorine rubber; thermoplastic resins such as polypropylene and polyethylene; imide resins such as polyimide and polyamideimide; alkoxysilyl group-containing resins; acrylic resins such as poly(meth)acrylic acid; styrene-butadiene rubber (SBR); carboxymethyl cellulose; alginates such as sodium alginate and ammonium alginate; water-soluble cellulose ester crosslinks; and starch-acrylic acid graft polymers.

[0024] The electrode material may optionally contain a solid electrolyte. The solid electrolyte is not particularly limited and may be appropriately selected from known materials depending on the target battery performance. Examples include oxide solid electrolytes and sulfide solid electrolytes.

[0025] The solvent is not particularly limited as long as it can properly disperse the electrode material. Examples include water and organic solvents. Examples of organic solvents include N-methyl-2-pyrrolidone, dimethylformamide, dimethylacetamide, methanol, acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methyl acetate, ethyl acetate, and tetrahydrofuran. These solvents may be used alone or in combination of two or more.

[0026] The coating method is not particularly limited as long as it can coat the current collector foil 10 with the slurry in a thin film form. For example, the current collector foil 10 can be coated with the slurry in any thickness using a known coating device.

[0027] <Drying process> The drying step is a step in which the coating film 20 formed on the current collector foil 10 is dried while being transported inside a drying furnace 30. An electrode is obtained by the drying step. A schematic diagram illustrating the drying step is shown in Figure 1. Figure 1 is a cross-sectional view of the drying furnace 30 taken along the transport direction X of the current collector foil 10.

[0028] As shown in Fig. 1, the current collector foil 10 on which the coating film 20 has been formed is transported using a plurality of transport rollers 31 installed inside a drying furnace 30. During this transport, the coating film 20 is dried by a heat source device 32 installed above the coating film 20. Typically, a plurality of heat source devices 32 are installed along the transport direction of the current collector foil 10. The transport speed is not particularly limited, but is, for example, in the range of 1 to 10 m / sec.

[0029] The heat source device 32 is a device that irradiates the coating film 20 with a heat source. In Figure 1, multiple heat source devices 32 are installed in the drying furnace 30, so the coating film 20 is irradiated with the heat source multiple times. However, the number of heat source devices 32 may be changed appropriately depending on the purpose, and at least one is sufficient. In other words, the drying process only requires that the coating film 20 be irradiated with the heat source at least once.

[0030] Here, the coating film 20 formed on the current collector foil 10 is conveniently divided into three regions. FIG. 2 shows a plan view of the coating film 20. As shown in FIG. 2, the coating film 20 is divided into three regions along the transport direction X, and has a central portion 21 located at the center in the width direction Y and end portions 22 located on both sides of the central portion 21. The width direction Y is the surface direction of the coating film 20, and is a direction perpendicular to the transport direction. The reason for dividing the coating film 20 into three regions in this way is as follows.

[0031] FIG. 3 shows a side view of the coating film 20. The coating film 20 formed on the current collector foil 10 has a thinner film thickness at its edge 22 than at its central portion 21 due to dripping caused by surface tension. As a result, the edge 22 of the coating film 20 dries more easily than the central portion 21 of the coating film 20. Furthermore, because drying also progresses from the sides of the coating film 20, the edge 22 of the coating film 20 dries more easily than the central portion 21 of the coating film 20 from this perspective as well. Therefore, the edge of the electrode obtained by drying the coating film 20 is likely to peel off from the current collector foil 10, which may result in a decrease in battery performance. This problem becomes more pronounced when a laser is used as the heat source.

[0032] To address this issue, the drying process of one embodiment is characterized by drying each end 22 of the coating film 20 with a low energy density heat source and drying the central portion 21 of the coating film 20 with a high energy density heat source.

[0033] This allows the drying times of the end portions 22 and the central portion 21 to be adjusted to be the same, thereby preventing the end portions of the resulting electrode from peeling off from the current collector foil 10. "The same drying time" means that the drying time of the central portion 21 and each end portion 22 of the coating film 20 is the same in the drying oven 30. However, this does not mean that they dry completely simultaneously, but rather that there is a predetermined time interval between them. Furthermore, adjusting the drying time of the central portion 21 and each end portion 22 of the coating film 20 to be the same has the advantage of enabling high-speed drying while downsizing the equipment. Furthermore, it also makes it possible to reduce the amount of binder added to the electrode material, thereby improving battery performance.

[0034] A high energy density heat source is one with an average energy density of 1W / cm 2 The heat source is, for example, a laser. Specific examples of the laser include a semiconductor laser, a direct laser, and a VCSEL laser. A laser with high focusing properties may be used. The frequency of laser irradiation in the transport direction may be pulsed or continuous. For reference, Figure 4(A) shows a schematic diagram of pulsed irradiation in the transport direction X, and Figure 4(B) shows a schematic diagram of continuous irradiation in the transport direction X.

[0035] A low energy density heat source is a heat source with a lower average energy density than a high energy density heat source. For example, a low energy density heat source with an average energy density of 1 W / cm 2 The heat source is less than 100°C. For example, it is hot air or a laser. The temperature of the hot air is not particularly limited, but is, for example, in the range of 100°C to 120°C. The speed of the hot air is not particularly limited, but is, for example, 3 m / s to 50 m / s. The hot air may be irradiated only to each end 22, or may be irradiated to the entire coating film 20. By irradiating the hot air, a large amount of gaseous solvent generated in the drying furnace 30 can be discharged to the outside of the furnace. This effect is exhibited even when the hot air is irradiated only to each end 22, but is more pronounced when the hot air is irradiated to the entire coating film 20. Specific examples of lasers include fiber lasers, direct lasers, and VCSFL lasers. A laser with high focusing properties may be used. The laser irradiation frequency in the transport direction may be pulsed or continuous (see Figure 4).

[0036] As described above, the drying process of one embodiment can be carried out by combining a high-energy density heat source and a low-energy density heat source. The mechanism by which the coating film 20 is dried simultaneously using these heat sources is as follows. First, the central portion 21 of the coating film 20 can be dried by irradiating the central portion 21 with a high-energy density heat source. Furthermore, each end portion 22 can be dried by heat conduction from the central portion 21 to each end portion 22. Furthermore, by irradiating each end portion 22 with a low-energy density heat source, combined with residual heat from the central portion 21, each end portion 22 can be dried simultaneously with the central portion 21. This allows the drying times of the central portion 21 and each end portion 22 of the coating film 20 to be adjusted to be the same.

[0037] Here, the formula for calculating the average energy density of the laser and hot air is shown below. (Laser average energy density (W / cm 2 )) = (laser energy density (W / cm 2)) ÷ (laser irradiation length in the transport direction (mm)) × (total length of drying oven in the transport direction (mm)) (Average hot air energy density (W / cm 2 )) = (Laser average energy density (W / cm 2 )) × (time (s) to dry the coating using only the laser) ÷ (time (s) to dry the coating using only hot air)

[0038] "The time required to dry the coating film using only a laser" refers to the time required to dry the coating film by irradiating the entire coating film with only a laser. "The time required to dry the coating film using only hot air" refers to the time required to dry the coating film by irradiating the entire coating film with only hot air.

[0039] When the sum of the average energy densities of the heat sources irradiated onto the central portion 21 of the coating film 20 is defined as EC and the sum of the average energy densities of the heat sources irradiated onto the edge 22 of the coating film 20 is defined as EE, the ratio EC / EE may be 1 or more and 4 or less. The reason for defining "EC as the sum of the average energy densities of the heat sources irradiated onto the central portion 21 of the coating film 20" is that the central portion 21 of the coating film 20 may be irradiated with other heat sources in addition to a high-energy-density heat source. For example, as shown in FIG. 5 (described later), the central portion 21 may be irradiated with a laser and hot air. In this case, EC is the sum of the average energy densities of the laser and hot air. The same applies to EE. That is, the edge 22 of the coating film 20 may be irradiated with other heat sources in addition to a low-energy-density heat source. This means that the edge 22 is irradiated with multiple low-energy-density heat sources. For example, the edge 22 may be irradiated with a laser and hot air. In this case, EE is the sum of the average energy densities of the laser and hot air. However, typically, end 22 is irradiated with a single low energy density heat source.

[0040] If EC / EE is less than 1, the energy density of the laser irradiated to each end 22 will be too high, and the drying time of the end 22 will be shorter than that of the central portion 21, which may make it difficult to prevent cracking or peeling of the end. If EC / EE exceeds 4, the energy density of the laser irradiated to each end 22 will be too low, and there is a risk that drying of the end 22 will not be completed. From the viewpoint of further improving the effect, EC / EE may be 2 or more and 4 or less.

[0041] Here, the coating film 20 will be further described. As described above, each edge 22 of the coating film 20 dries simultaneously with the central portion 21 due to heat conduction from the central portion 21, which is irradiated with a high-energy density heat source, in addition to irradiation with a low-energy density heat source. Therefore, the extent of each edge 22 is set in consideration of the above mechanism so that it dries simultaneously with the central portion 21. Therefore, the specific extent of the edge 22 of the coating film 20 is not particularly limited and varies depending on the type of high-energy density heat source and the low-energy density heat source and the average energy density. For example, the edge 22 of the coating film 20 may be a region extending from the outermost edge in the width direction of the coating film 20 to a width of 3 to 18 mm inward from the starting point (i.e., the width length of the edge 22 of the coating film 20 may be 3 to 18 mm). Alternatively, the edge 22 of the coating film 20 may be a region extending from the starting point to a width of 5 to 18 mm inward (i.e., the width length of the edge 22 of the coating film 20 may be 5 to 18 mm).

[0042] Furthermore, the width direction length of the coating film 20 is not particularly limited, but the drying step of one embodiment is suitable for a coating film 20 having a long width direction length. This is because the longer the width direction length of the coating film 20, the more likely it is that uneven drying will occur. For example, the width direction length of the coating film 20 may be 1000 mm or more and 1500 mm or less.

[0043] Next, a description will be given of a heat source device 32 capable of carrying out the drying step of one embodiment. The heat source device 32 can be realized by combining a high-energy density heat source device capable of irradiating a center portion 21 of the coating film 20 with a high-energy density heat source and a low-energy density heat source device capable of irradiating each end portion 22 of the coating film 20 with a low-energy density heat source.

[0044] FIG. 5 shows a heat source device 132, an example of the heat source device 32. The heat source device 132 is a combination of a laser irradiation device 133, which is a high-energy density heat source device, and a hot air irradiation device 134, which is a low-energy density heat source device. As shown in FIG. 5, the laser irradiation device 133 has multiple laser irradiation units 133a arranged in the width direction, and is capable of irradiating a laser onto the central portion 21 of the coating film 20. The area indicated by L in FIG. 5 is the laser irradiation range. The number of laser irradiation units 133a is not particularly limited as long as the entire width of the central portion 21 can be set as the laser irradiation range. FIG. 5 shows an example of a laser irradiation device 133 equipped with three laser irradiation units 133a. The hot air irradiation device 134 has a length equal to or greater than the width of the coating film 20 and is arranged across the width of the coating film 20. Thus, hot air can be irradiated onto the entire width of the coating film 20. The area indicated by W in FIG. 5 is the hot air irradiation range. By using such a heat source device 132, the drying step of one embodiment can be carried out, and the drying time can be adjusted to be the same for the center and edges of the coating film 20. The hot air irradiating devices 134 are not limited to being arranged across the width of the coating film 20 as shown in Figure 5, but may be arranged outward in the width direction of the laser irradiating devices 233, and may irradiate hot air to each edge 22 of the coating film 20.

[0045] FIG. 6 shows a heat source device 232, another example of the heat source device 32. The heat source device 232 is a combination of a laser irradiation device (high-energy density laser irradiation device) 233, which is a high-energy density heat source device, and laser irradiation devices (low-energy density laser irradiation devices) 234, 234, which are low-energy density heat source devices. The average energy density of the laser irradiated from the high-energy density laser irradiation device 233 is set higher than the average energy density of the laser irradiated from the low-energy density laser irradiators 234, 234. As shown in FIG. 6, the high-energy density laser irradiation device 233 is exemplified by a device having a structure similar to that of the laser irradiation device 133 in FIG. 5. As shown in FIG. 6, the range indicated by L1 is the irradiation range of the high-energy density laser. The low-energy density laser irradiation devices 234, 234 are each positioned outward in the width direction from the laser irradiation device 233, and are capable of irradiating the entire width direction of each end 22 of the coating film 20 with a laser. As shown in FIG. 6, the range indicated by L2 is the irradiation range of the low-energy density laser. In FIG. 6, the low energy density laser irradiation devices 234, 234 are provided with one laser irradiation unit, but are not limited to this configuration and may be provided with a plurality of laser irradiation units.

[0046] The method for manufacturing an electrode according to the present disclosure has been described above using one embodiment. The method for manufacturing an electrode according to the present disclosure can prevent the electrode from peeling off from the current collecting foil.

[0047] [Battery manufacturing method] The method for manufacturing a battery according to the present disclosure will be described using one embodiment.

[0048] One embodiment is a battery manufacturing method including an electrode manufacturing step of obtaining an electrode using the above-described electrode manufacturing method, and a battery manufacturing step of assembling a battery using the electrode. Since the electrode manufacturing step has been described above, the battery manufacturing step will be described below.

[0049] The battery fabrication process is a process of assembling a battery using the electrode obtained in the electrode fabrication process. Such a battery fabrication process is known. A typical example in which the electrode obtained in the electrode fabrication process is a positive electrode will be described below, but the present invention is not limited to this example.

[0050] When the electrode obtained in the electrode preparation step is a positive electrode, a battery is prepared using a separately prepared negative electrode and electrolyte layer.

[0051] When the electrolyte is a liquid electrolyte, a battery can be fabricated by placing a separator between the positive electrode and the negative electrode and then supplying the electrolyte to the separator. The separator is typically a porous polyolefin sheet. The electrolyte is a non-aqueous solvent with a supporting salt dissolved in it. Examples of non-aqueous solvents include carbonates, ethers, and esters. Examples of supporting salts include LiPF6, LiBF4, lithium bis(fluorosulfonyl)imide (LiFSI), and lithium bis(trifluoromethane)sulfonimide (LiTFSI).

[0052] When the electrolyte is a solid electrolyte, a battery can be fabricated by disposing a solid electrolyte layer between a positive electrode and a negative electrode. The solid electrolyte layer contains a solid electrolyte. The solid electrolyte layer may also contain a binder. The solid electrolyte and binder may be appropriately selected from the solid electrolytes and binders described above.

[0053] The battery manufacturing method according to the present disclosure has been described above using one embodiment. The battery manufacturing method according to the present disclosure manufactures electrodes based on the electrode manufacturing method described above, thereby suppressing peeling of the electrodes from the current collecting foil. Therefore, the battery manufacturing method according to the present disclosure can suppress deterioration of battery performance due to electrode peeling. [Example]

[0054] [Relationship between the edge area of ​​the coating film and the residual moisture content after drying] A slurry of electrode material dispersed in a solvent was applied to the current collector foil to form a coating, which was then placed in a drying oven to dry. The width of the coating was adjusted to 1160 mm.

[0055] The heat source device of the drying oven was constructed following the configuration shown in Figure 5. That is, a heat source device combining a laser irradiation device and a hot air irradiation device was used. The average energy density of the laser irradiated from the laser irradiation device was 0.44 W / cm. 2 The average energy density of the hot air irradiated from the hot air irradiation device was set to 0.19 W / cm 2 The EC / EE ratio was calculated from these values ​​to be 2.32. The width of the hot air irradiation device was set to 1160 mm.

[0056] Here, the width of each edge of the coating film was varied to 5 mm, 10 mm, 18 mm, and 20 mm, i.e., the width of the center of the coating film (the laser irradiation range) was varied to 1150 mm, 1140 mm, 1124 mm, and 1120 mm. The moisture content of the electrode edge after drying was measured. The moisture content was calculated by cutting a piece of the electrode and calculating the weight ratio of the piece before and after drying. The results are shown in Figure 7.

[0057] As shown in Figure 7, when the width direction length of each end of the coating film was set to 5 mm, 10 mm, or 18 mm, the residual moisture rate in the electrode end was 0%, and the electrode end was completely dry. On the other hand, when the width direction length of each end of the coating film was set to 20 mm, the residual moisture rate in the electrode end was 0.16%, and the electrode end was not completely dry. From these results, it is considered desirable to set the width direction length of each end of the coating film to 18 mm or less.

[0058] [Relationship between coating position and drying time] A slurry of electrode material dispersed in a solvent was applied onto the current collector foil to form a coating, which was then placed in a drying oven to dry. The width of the coating was adjusted to 1000 mm.

[0059] The heat source device of the drying oven was constructed following the configuration shown in Figure 8. That is, a heat source device combining a laser irradiation device and a hot air irradiation device was used. Then, after the coating film was stopped at a predetermined position in the drying oven, the coating film was dried using a laser and hot air.

[0060] The laser irradiation device and hot air irradiation device used in the examples and comparative examples are as follows. Example: Laser average energy density 1.2 W / cm 2 A laser irradiation device capable of irradiating a laser beam with a width of 960 mm and a speed of 10 m / s was used. The edges were not irradiated with laser. A hot air irradiation device capable of irradiating a hot air beam with a width of 1100 mm and a speed of 10 m / s was used. Comparative example: Laser average energy density 1.2 W / cm 2 A laser irradiation device capable of irradiating a laser beam measuring 1100 mm in width was used. Also, a hot air irradiation device capable of irradiating hot air measuring 10 m / s in width and 1100 mm in width was used.

[0061] The measurement points 1 to 5 shown in Figure 8 will now be explained. Measurement points 1 and 5 are the edges of the coating film, and points 2 to 4 are the measurement positions when the central part is divided into three parts. The drying time at each measurement point was measured from the temperatures of the front and back surfaces. The surface temperature was measured using a thermoviewer. The back surface temperature was measured using a thermocouple. The results are shown in Figure 8.

[0062] As shown in Figure 8, in the comparative example, the drying time of the edges was shorter than that of the center, while in the example, the drying time of the center and edges was the same. From this result, it is thought that the drying times of the center and edges can be adjusted to be the same by adjusting the average energy density of the heat source irradiated to the center and edges.

[0063] [Laser energy density map] As shown in Figure 9, three laser irradiation devices 1 to 3 with different energy densities were installed. The irradiation width of each laser irradiation device was set to 400 mm. The average energy density of the laser irradiated from the laser irradiation devices was as follows: Laser irradiation device 1:1W / cm2 Laser irradiation device 2: 2.5W / cm 2 Laser irradiation device 3:1W / cm 2

[0064] The laser energy density map (temperature distribution) was obtained by irradiating each laser onto a heat-resistant block and measuring the block surface with a thermoviewer. The results are shown in Figure 9.

[0065] As shown in Figure 9, the temperature of the part irradiated by laser irradiation device 2 was high, while the temperatures of the parts irradiated by laser irradiation devices 1 and 3 were low. This result also suggests that by adjusting the average energy density of the heat source irradiated to the center and edges, it is possible to adjust the drying times of the center and edges to be the same. [Explanation of symbols]

[0066] 10 Current collecting foil 20 Paint film 21 Central part 22 End 30 Drying oven 31 Transport roller 32, 132, 232 Heat source equipment 133 Laser irradiation device 134 Hot air irradiation device 233 High Energy Density Laser Irradiation Device 234 Low Energy Density Laser Irradiation Device

Claims

1. a coating step of coating a current collecting foil with a slurry obtained by dispersing an electrode material in a solvent to obtain a coating film; a drying step of drying the coating film while transporting the current collecting foil on which the coating film has been formed in a drying furnace, the coating film is divided into three regions along the transport direction, and has a central portion disposed at the center in the width direction and end portions disposed on both sides of the central portion, In the drying step, each of the edges of the coating film is dried with hot air, which is a heat source with a low energy density, and the central part of the coating film is dried with a laser, which is a heat source with a high energy density. Electrode manufacturing method.

2. The drying process dries both the ends and the center of the coating film by irradiating them with hot air, which is a low-energy density heat source, and dries the center of the coating film by irradiating it with a laser, which is a high-energy density heat source, and the range that is dried by irradiating it with the high-energy density heat source entirely overlaps with the range that is dried by irradiating it with the low-energy density heat source in the transport direction. A method for manufacturing the electrode according to claim 1 .

3. 3. The method for producing an electrode according to claim 1, wherein the end of the coating film is a region extending from an outermost end of the coating film in the width direction to an inner side in the width direction by 3 to 18 mm when the end of the coating film is taken as a starting point.

4. The method for producing an electrode according to claim 1 or 2, wherein the length of the coating film in the width direction is 1000 mm or more and 1500 mm or less.

5. an electrode production step of obtaining an electrode by using the electrode production method according to claim 1 or 2; A battery fabrication step of assembling a battery using the electrode. How batteries are manufactured.

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