Method for manufacturing electrode

Abstract

A method for manufacturing an electrode, the method comprising: a coating step for coating a current collector foil with a slurry obtained by dispersing an electrode material in a solvent to obtain a coating film; and a drying step in which the current collector foil on which the coating film is formed is conveyed inside a drying furnace while the coating film is dried, the coating film having three regions divided in the conveying direction, i.e., a central portion disposed in the center in the width direction and end portions disposed on both sides of the central portion, in the drying step, each end portion of the coating film is dried by a low-energy-density heat source, and the center portion of the coating film is dried by a high-energy-density heat source.

Description

Technical Field

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

[0002] Conventionally, there is known a method for producing an electrode, in which a slurry obtained by dispersing an electrode material in a solvent is applied on 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, Japanese Patent Application Laid-Open No. 2013-084383 discloses a method for manufacturing an electrode, wherein after a mesh collector foil is coated with a slurry for forming an electrode composite material layer, the collector foil coated with the slurry is conveyed in one direction in a drying furnace while hot air is blown to dry the coating. Summary of the invention

[0004] The coating formed on the collector foil has a thinner film thickness at the end than in the center due to the dripping of liquid under surface tension. As a result, the coating is easier to dry at the end than at the center. Therefore, the end of the electrode obtained by drying the coating is easy to peel off from the collector foil, and the battery performance may be reduced.

[0005] Therefore, a main object of the present disclosure is to provide a method for producing an electrode capable of suppressing separation of the electrode from a current collector foil.

[0006] The present disclosure provides at least the following aspects.

[0007] A method for manufacturing an electrode according to a first aspect includes: a coating step of coating a slurry obtained by dispersing an electrode material in a solvent on the collector foil to obtain a coating film; and In the drying process, the current collector foil with the coating formed thereon is conveyed inside a drying furnace while the coating is dried. The coating film has three regions divided along the conveying direction, namely, a central portion arranged in the center in the width direction, and end portions arranged on both sides of the central portion. In the drying step, each end portion of the coating film is dried using a heat source with a low energy density, and the center portion of the coating film is dried using a heat source with a high energy density.

[0008] According to the electrode manufacturing method described in the first aspect, in the second aspect, in the drying step, the heat source with low energy density is hot air or laser, and the heat source with high energy density is laser.

[0009] According to the method for manufacturing an electrode described in the second embodiment, in a third embodiment, when the sum of average energy densities of heat sources irradiated to the central portion of the coating film is defined as EC, and the sum of average energy densities of heat sources irradiated to the end portions of the coating film is defined as EE, EC / EE calculated based on the following formula is greater than or equal to 1 and less than or equal to 4, (Laser average energy density (W / cm 2 ))=(Laser energy density (W / cm 2 ))÷(laser irradiation length in the conveying direction (mm))×(total length of the drying furnace in the conveying direction (mm)), (Average energy density of hot air (W / cm 2 ))=(Laser average energy density (W / cm 2 ))×(time (s) when the coating film is dried only by laser)÷(time (s) when the coating film is dried only by hot air).

[0010] According to the method for producing an electrode described in any one of the first to third aspects, in a fourth aspect, when the endmost portion in the width direction of the coating film is defined as the starting point, the end portion of the coating film is a region extending from 3 mm to 18 mm inward in the width direction from the starting point.

[0011] In a fifth aspect, the method for producing an electrode according to any one of the first to fourth aspects, the length of the coating film in the width direction is 1000 mm to 1500 mm.

[0012] A method for manufacturing a battery comprises: an electrode manufacturing step of obtaining an electrode using the electrode manufacturing method described in any one of the first to fifth aspects; and a battery manufacturing step of assembling a battery using the electrode.

[0013] According to the method for producing an electrode of the present disclosure, it is possible to suppress the electrode from peeling off from the current collector foil. In addition, according to the method for producing a battery of the present disclosure, it is possible to suppress the reduction in battery performance due to the peeling off of the electrode. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which like reference numerals represent like elements. Figure 1 is a cross-sectional view obtained by cutting the drying furnace 30 along the conveying direction X of the collector foil 10; Figure 2 is a top view of the coating film 20; Figure 3 is a side view of the coating film 20; Figure 4A This is a schematic diagram of pulse irradiation in the conveying direction X; Figure 4B It is a schematic diagram of continuous irradiation in the conveying direction X; Figure 5 is a schematic diagram of a heat source device 132 as an example of the heat source device 32; Figure 6 is a schematic diagram of a heat source device 232 as an example of the heat source device 32; Figure 7 The experimental results show the relationship between the range of the end of the coating film and the residual moisture after drying; Figure 8 It is an experimental result showing the relationship between the coating position and the drying time; Fig. 9 is an experimental result showing laser energy density mapping. DETAILED DESCRIPTION Electrode manufacturing method

[0015] The method for producing an electrode of the present disclosure will be described using one embodiment.

[0016] The electrode manufacturing method according to one embodiment includes: a coating step of coating a slurry obtained by dispersing an electrode material in a solvent on a collector foil 10 to obtain a coating film 20 ; and a drying step of drying the coating film 20 while conveying the collector foil 10 formed with the coating film 20 inside a drying furnace 30 . Coating process

[0017] The coating step is a step of coating the current collector foil 10 with a slurry obtained by dispersing an electrode material in a solvent to obtain a coating film 20. Such a coating step is well known. A typical example will be described below, but the present invention is not limited to this embodiment.

[0018] The collector foil 10 can be a sheet-shaped conductive component without any particular limitation. For example, the collector foil 10 can be a metal foil made of metals such as stainless steel, copper, aluminum, titanium, and nickel. The metal foil can also be made of an alloy containing two or more of these metals. In addition, the metal foil can also be subjected to surface treatments such as plating. The collector foil 10 can also be made of two or more metal foils. In this case, the metal foils can be joined by adhesives or the like, or by stamping or the like.

[0019] The electrode material contains at least an active material. The active material is a positive electrode active material or a negative electrode active material. The positive electrode active material is not particularly limited and can be appropriately selected from known materials according to the target battery performance. Examples thereof include composite oxides, metallic lithium, and sulfur. The composition of the composite oxide includes, for example, at least one of iron, manganese, titanium, nickel, cobalt, and aluminum and lithium. As an example of a composite oxide, olivine-type lithium iron phosphate (LiFePO 4 ). The negative electrode active material is not particularly limited and can be appropriately selected from known materials according to the target battery performance. Examples thereof include graphite, artificial graphite, highly oriented graphite, secondary carbon microbeads, hard carbon, soft carbon and other carbons, metal compounds, elements or compounds thereof that can alloy with lithium, boron-doped carbon, etc. Examples of elements that can alloy with lithium include silicon and tin.

[0020] When the electrode material contains a positive electrode active material, the final electrode becomes a positive electrode. On the contrary, when the electrode material contains a negative electrode material, the final electrode becomes a negative electrode.

[0021] The electrode material may optionally contain a conductive aid. The conductive aid is not particularly limited and may be appropriately selected from known materials according to the target battery performance. Examples thereof include acetylene black, carbon black, graphite, and the like.

[0022] The electrode material may arbitrarily include a binder. The binder is not particularly limited and can be appropriately selected from known materials according to the target battery performance. For example, polyvinylidene fluoride, polytetrafluoroethylene, fluorine-containing resins such as fluorine rubber, thermoplastic resins such as polypropylene and polyethylene, imide resins such as polyimide and polyamide-imide, alkoxysilyl-containing resins, acrylic resins such as poly(meth)acrylic acid, styrene-butadiene rubber (SBR), carboxymethyl cellulose, sodium alginate, alginate such as ammonium alginate, water-soluble cellulose ester crosslinked products, starch-acrylic acid graft polymers, etc. can be cited.

[0023] The electrode material may arbitrarily include a solid electrolyte. The solid electrolyte is not particularly limited and may be appropriately selected from known materials according to the target battery performance. Examples thereof include oxide solid electrolytes, sulfide solid electrolytes, and the like.

[0024] 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, tetrahydrofuran, etc. These solvents may be used alone or in combination of two or more.

[0025] The coating method is not particularly limited, and any method is sufficient as long as the slurry can be coated in a thin film on the collector foil 10. For example, the slurry can be coated on the collector foil 10 in an arbitrary thickness using a known coating device. Drying process

[0026] The drying step is a step of drying the coating film 20 while conveying the current collector foil 10 on which the coating film 20 is formed inside the drying furnace 30. The electrode is obtained through the drying step. Figure 1 A schematic diagram illustrating the drying process is shown in FIG. Figure 1 This is a cross-sectional view obtained by cutting the drying furnace 30 along the conveyance direction X of the collector foil 10 .

[0027] like Figure 1As shown, the collector foil 10 formed with the coating film 20 is conveyed using a plurality of conveying rollers 31 provided inside a drying furnace 30. At this time, the coating film 20 is dried by a heat source device 32 provided on the upper portion of the coating film 20. Typically, a plurality of heat source devices 32 are provided along the conveying direction of the collector foil 10. The conveying speed is not particularly limited, and is, for example, in the range of 1 m / sec to 10 m / sec.

[0028] The heat source device 32 is a device for irradiating the coating film 20 with a heat source. Figure 1 In the drying process, a plurality of heat source devices 32 are provided in the drying furnace 30, so the coating film 20 is irradiated with the heat source multiple times. However, the number of the heat source devices 32 can be appropriately changed according to the target, and at least one is sufficient. That is, the coating film 20 is irradiated with the heat source at least once in the drying process.

[0029] Here, the coating film 20 formed on the current collector foil 10 is divided into three regions for convenience. Figure 2 A top view of the coating film 20 is shown in FIG. Figure 2 As shown, the coating film 20 has three regions divided along the conveying direction X, namely, a central portion 21 arranged in the center of the width direction Y, and end portions 22 arranged on both sides of the central portion 21. The width direction Y refers to a direction orthogonal to the conveying direction in the surface direction of the coating film 20. The reason for dividing the coating film 20 into three regions like this is as follows.

[0030] Figure 3 , a side view of the coating film 20 is shown in FIG. The coating film 20 formed on the collector foil 10 has a film thickness at the end 22 that is thinner than the central portion 21 due to the dripping of liquid under surface tension. In this way, the drying progresses more easily at the end 22 of the coating film 20 than at the central portion 21 of the coating film 20. In addition, the drying progresses more easily from the side of the coating film 20, so from this point of view, the drying progresses more easily at the end 22 of the coating film 20 than at the central portion 21 of the coating film 20. Therefore, the end of the electrode obtained by drying the coating film 20 is easily peeled off from the collector foil 10, and the battery performance may be reduced. This problem is more significant when a laser is used as a heat source.

[0031] To address such a problem, a drying step according to one embodiment is characterized in that each end portion 22 of the coating film 20 is dried using a heat source with a low energy density, and the center portion 21 of the coating film 20 is dried using a heat source with a high energy density.

[0032] Thus, the drying time of each end 22 and the central portion 21 can be adjusted to be the same, and the situation that the end of the obtained electrode is peeled off from the collector foil 10 can be suppressed. "The same drying time" means that the drying completion time of the central portion 21 and each end 22 of the coating 20 in the drying furnace 30 is the same, but this does not mean completely at the same time, but means that there is a specified time width. In addition, by making the drying time of the central portion 21 and each end 22 of the coating 20 the same, it has the advantage of being able to achieve high-speed drying while reducing the equipment. Moreover, the amount of binder added in the electrode material can also be reduced, and the battery performance can also be improved.

[0033] High energy density heat source refers to the average energy density of 1W / cm 2 The heat source is a laser. Specific examples of lasers include semiconductor lasers, direct lasers, and VCSEL lasers. Lasers with high focusing properties can be used. In addition, the irradiation frequency of the laser can be either pulse irradiation or continuous irradiation in the conveying direction. For reference, Figure 4A A schematic diagram of pulse irradiation relative to the transport direction X is shown in FIG. Figure 4B , a schematic diagram showing continuous irradiation with respect to the transport direction X is shown.

[0034] A low energy density heat source refers to a heat source with a lower average energy density than a high energy density heat source. For example, a heat source with an average energy density of less than 1 W / cm 2 The heat source is, for example, hot air or laser. The temperature of the hot air is not particularly limited, for example, it is in the range of 100°C to 120°C. The wind speed of the hot air is not particularly limited, for example, it is 3m / s to 50m / s. The hot air may be irradiated only to each end 22, but the coating 20 as a whole may also be irradiated. By irradiating with 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 can be exerted even in the case of irradiating the hot air only to each end 22, but it can be exerted significantly in the case of irradiating the coating 20 as a whole. Specific examples of lasers include fiber lasers, direct lasers, VCSFL lasers, and the like. Lasers with high focusing properties can be used. In addition, the irradiation frequency of the laser may be either pulse irradiation in the conveying direction or continuous irradiation (see Figure 4A , Figure 4B ).

[0035] As such, the drying process of one embodiment can be implemented by combining a heat source with a high energy density and a heat source with a low energy density. The mechanism of simultaneously drying the coating film 20 using these heat sources is as follows. First, by irradiating the central portion 21 of the coating film 20 with a heat source with a high energy density, the central portion 21 can be dried. In addition, by heat conduction from the central portion 21 to each end portion 22, each end portion 22 can be dried. Furthermore, by irradiating each end portion 22 with a heat source with a low energy density, each end portion 22 can be dried simultaneously with the central portion 21 in a complementary manner with the residual heat from the central portion 21. Thus, the drying time of the central portion 21 and each end portion 22 of the coating film 20 can be adjusted to be the same.

[0036] Here, calculation formulas for the average energy density of laser light and hot air are shown. (Laser average energy density (W / cm 2 ))=(Laser energy density (W / cm 2 ))÷(Laser irradiation length in the conveying direction (mm))×(Overall length of the drying furnace in the conveying direction (mm)) (Average energy density of hot air (W / cm 2 ))=(Laser average energy density (W / cm 2 )) × (Time (s) when the coating is dried using only laser) ÷ (Time (s) when the coating is dried using only hot air)

[0037] The “time for drying the coating film by laser alone” means the time for drying the coating film by irradiating the entire coating film with laser alone. The “time for drying the coating film by hot air alone” means the time for drying the coating film by irradiating the entire coating film with hot air alone.

[0038] When the sum of the average energy densities of the heat sources irradiating 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 irradiating the end portions 22 of the coating film 20 is defined as EE, EC / EE may be greater than or equal to 1 and less than or equal to 4. The reason for "the sum of the average energy densities of the heat sources irradiating the central portion 21 of the coating film 20 is defined as EC" is that in addition to the heat sources with high energy density, other heat sources may be irradiated to the central portion 21 of the coating film 20. For example, as described later, Figure 5 As shown, the central portion 21 is irradiated with laser and hot air. In this case, EC becomes the sum of the average energy densities of the laser and the hot air. The same is true for EE. That is, there is a case where the end portion 22 of the coating 20 is irradiated with other heat sources in addition to the low energy density heat source. This means that a plurality of low energy density heat sources are irradiated to the end portion 22. For example, the end portion 22 may also be irradiated with laser and hot air. In this case, EE becomes the sum of the average energy densities of the laser and the hot air. However, usually a single low energy density heat source is irradiated to the end portion 22.

[0039] If EC / EE is less than 1, the energy density of the laser irradiated to each end 22 is too high, and the drying time of the end 22 becomes shorter than that of the central portion 21, and it may not be possible to suppress the cracking and peeling of the end. If EC / EE exceeds 4, the energy density of the laser irradiated to each end 22 is too low, and the drying of the end 22 may not be completed. From the perspective of further improving the effect, EC / EE may be set to 2 or more and 4 or less.

[0040] Here, the coating film 20 is further described. As described above, in addition to the irradiation of the heat source with low energy density, each end 22 of the coating film 20 is dried by heat conduction from the central part 21 irradiated with a high energy density heat source, and is dried simultaneously with the central part 21. Therefore, the range of each end 22 is set to be dried simultaneously with the central part 21 in consideration of the above mechanism. Therefore, the range of the end 22 of the specific coating film 20 is not particularly limited, and varies according to the type and average energy density of the heat source with high energy density and the heat source with low energy density. For example, when the end in the width direction of the coating film 20 is set as the starting point, the end 22 of the coating film 20 can be set to a region of 3mm to 18mm from the starting point toward the inner side in the width direction (that is, the width direction length of the end 22 of the coating film 20 can be set to 3mm to 18mm). In addition, the end 22 of the coating film 20 can also be set to a region of 5mm to 18mm from the above starting point toward the inner side in the width direction (that is, the width direction length of the end 22 of the coating film 20 can be set to 5mm to 18mm).

[0041] In addition, the width direction length of the coating film 20 is not particularly limited, and the drying process of one embodiment is suitable for a coating film 20 with a long width direction length. This is because the longer the width direction length of the coating film 20, the easier it is to produce uneven drying. For example, the width direction length of the coating film 20 can be set to 1000 mm or more and 1500 mm or less.

[0042] Next, a heat source device 32 capable of implementing a drying process of an embodiment will be described. The heat source device 32 can be realized by combining a high energy density heat source device capable of irradiating a high energy density heat source to the central portion 21 of the coating film 20 and a low energy density heat source device capable of irradiating a low energy density heat source to each end portion 22 of the coating film 20.

[0043] Figure 5 FIG. 1 shows a heat source device 132 as an example of the heat source device 32. The heat source device 132 is a combination of a laser irradiation device 133 as a high energy density heat source device and a hot air irradiation device 134 as a low energy density heat source device. Figure 5As shown, the laser irradiation device 133 is formed by arranging a plurality of laser irradiation parts 133 a in the width direction, and can irradiate the central part 21 of the coating film 20 with laser light. Figure 5 The range indicated by L in the figure is the laser irradiation range. The number of laser irradiation portions 133a is not particularly limited, as long as the entire width direction of the central portion 21 can be set as the laser irradiation range. Figure 5 , a laser irradiation device 133 having three laser irradiation units 133a is illustrated. The hot air irradiation device 134 has a length greater than the length in the width direction of the coating film 20 and is arranged across the width direction of the coating film 20. In addition, the hot air can be irradiated over the entire width direction of the coating film 20. Figure 5 The range indicated by W in the figure is the hot air irradiation range. By using such a heat source device 132, a drying process of an embodiment can be implemented, and the drying time of the central part and the end part of the coating film 20 can be adjusted to be the same. In addition, the hot air irradiation device 134 is not limited to Figure 5 The above-mentioned configuration across the width direction of the coating film 20 may be a configuration in which each of the laser irradiation devices 233 is disposed outside in the width direction and hot air is irradiated to each end portion 22 of the coating film 20 .

[0044] in addition, Figure 6 2 shows a heat source device 232 as 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 as a high energy density heat source device and laser irradiation devices (low energy density laser irradiation devices) 234, 234 as 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 to be higher than the average energy density of the laser irradiated from the low energy density laser irradiation devices 234, 234. Figure 6 As shown, the high energy density laser irradiation device 233 exemplifies Figure 5 The laser irradiation device 133 has the same structure. Figure 6 As shown in FIG. 1 , the range indicated by L1 is the irradiation range of the high energy density laser. The low energy density laser irradiation devices 234 and 234 are respectively arranged outside the laser irradiation device 233 in the width direction, and can irradiate the entire width direction of each end portion 22 of the coating film 20 with laser. Figure 6 As shown, the range indicated by L2 is the irradiation range of the low energy density laser. Figure 6 In the figure, the low energy density laser irradiation devices 234 and 234 include one laser irradiation unit, but are not limited to this form, and may include a plurality of laser irradiation units.

[0045] The method for producing an electrode of the present disclosure has been described above using one embodiment. According to the method for producing an electrode of the present disclosure, it is possible to suppress the electrode from peeling off from the current collector foil. Battery manufacturing method

[0046] The method for manufacturing the battery of the present disclosure will be described using one embodiment.

[0047] One embodiment is a method for manufacturing a battery, comprising: an electrode manufacturing step, using the electrode manufacturing method to obtain an electrode; and a battery manufacturing step, using the electrode to assemble a battery. The electrode manufacturing step has been described above, so the battery manufacturing step will be described below.

[0048] The battery manufacturing process is a process of assembling a battery using the electrode obtained in the electrode manufacturing process. Such a battery manufacturing process is well known. A typical example in which the electrode obtained in the electrode manufacturing process is a positive electrode is described below, but the present invention is not limited to this mode.

[0049] When the electrode obtained in the electrode production step is a positive electrode, a battery is produced using a negative electrode and an electrolyte layer produced separately.

[0050] When the electrolyte is a liquid electrolyte, the battery can be made by placing a separator between the positive electrode and the negative electrode and then supplying an electrolyte to the separator. The separator is mainly a porous sheet of a polyolefin system. The electrolyte is prepared by dissolving a supporting salt in a non-aqueous solvent. Examples of the non-aqueous solvent include carbonates, ethers, esters, etc. Examples of the supporting salt include LiPF 6 , LiBF 4 , lithium bis(fluorosulfonyl)imide (LiFSI), lithium bis(trifluoromethane)sulfonylimide (LiTFSI), etc.

[0051] When the electrolyte is a solid electrolyte, a battery can be made by configuring a solid electrolyte layer between the positive electrode and the negative electrode. The solid electrolyte layer contains a solid electrolyte. In addition, the solid electrolyte layer may also contain a binder. The solid electrolyte and the binder can be appropriately selected from the above-mentioned solid electrolytes and binders.

[0052] The above is a description of the manufacturing method of the battery disclosed in the present invention using one embodiment. The manufacturing method of the battery disclosed in the present invention manufactures the electrode based on the above-mentioned electrode manufacturing method, so the electrode is prevented from peeling off from the collector foil. Therefore, according to the manufacturing method of the battery disclosed in the present invention, the reduction of battery performance caused by the peeling off of the electrode can be suppressed. Example Relationship between the range of the end of the coating film and the residual moisture after drying

[0053] After applying a slurry obtained by dispersing an electrode material in a solvent onto the collector foil to obtain a coating, the collector foil with the coating formed thereon was introduced into a drying furnace to dry the coating. The width direction length of the coating was adjusted to 1160 mm.

[0054] The heat source device of the drying furnace is modeled after Figure 5 That is, a heat source device combining a laser irradiation device and a hot air irradiation device is used. The average energy density of the laser irradiated from the laser irradiation device is set to 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 EC / EE was calculated from these values ​​and was 2.32. The widthwise length of the hot air irradiation device was set to 1160 mm.

[0055] Here, the moisture content in the electrode ends after drying was measured when the width length of each end of the coating was changed to 5mm, 10mm, 18mm, and 20mm, and the width length of the central part of the coating (laser irradiation range) was changed to 1150mm, 1140mm, 1124mm, and 1120mm. The moisture content was calculated based on the weight ratio of the electrode before and after drying. The results are shown in Figure 7 .

[0056] like Figure 7 As shown in the figure, when the length of each end of the coating film in the width direction is set to 5 mm, 10 mm, or 18 mm, the residual moisture rate in the electrode end is 0%, and the electrode end is completely dry. On the other hand, when the length of each end of the coating film in the width direction is set to 20 mm, the residual moisture rate in the electrode end is 0.16%, and the electrode end is not completely dry. Based on this result, it can be considered that the length of each end of the coating film in the width direction is preferably set to 18 mm or less. Relationship between coating position and drying time

[0057] After applying a slurry obtained by dispersing an electrode material in a solvent onto the collector foil to obtain a coating film, the collector foil with the coating film formed thereon was introduced into a drying furnace to dry the coating film. The width direction length of the coating film was adjusted to 1000 mm.

[0058] The heat source device of the drying furnace is modeled after Figure 8 That is, a heat source device combining a laser irradiation device and a hot air irradiation device is used. After the coating film is stopped at a predetermined position in the drying furnace, the coating film is dried using laser and hot air.

[0059] The laser irradiation device and the hot air irradiation device used in the examples and comparative examples are as follows. Example: Using a laser that can irradiate with an average energy density of 1.2 W / cm 2The laser irradiation device of the laser beam of 960 mm in width was used. The end portion was not irradiated with laser beam. In addition, a hot air irradiation device capable of irradiating hot air of 10 m / s in wind speed and 1100 mm in width was used. Comparative example: A laser with an average energy density of 1.2 W / cm 2 A laser irradiation device capable of irradiating a laser beam with a width of 1100 mm was used. A hot air irradiation device capable of irradiating hot air with a wind speed of 10 m / s and a width of 1100 mm was also used.

[0060] right Figure 8 The measurement locations 1 to 5 shown are explained. Measurement locations 1 and 5 are the ends of the coating film, and locations 2 to 4 are the measurement locations when the central part is divided into three. The drying time of each measurement location is measured based on the surface and back surface temperatures. The surface temperature is measured using a thermal observation instrument. The back surface temperature is measured using a thermocouple. The results are shown in Figure 8 .

[0061] like Figure 8 As shown in the figure, in the comparative example, the drying time of the end portion is shorter than that of the central portion, while in the embodiment, the drying time of the central portion and the end portion is the same. Based on this result, it can be considered that by adjusting the average energy density of the heat source irradiated to the central portion and the end portion, the drying time of the central portion and the end portion can be adjusted to be the same. Laser energy density mapping

[0062] like Fig. 9 As shown, three laser irradiation devices 1 to 3 with different energy densities are provided. The irradiation width of each laser irradiation device is set to 400 mm. In addition, the average energy density of the laser irradiated from the laser irradiation device is as follows. Laser irradiation device 1: 1W / cm 2 Laser irradiation device 2: 2.5W / cm 2 Laser irradiation device 3: 1W / cm 2

[0063] Laser energy density mapping (temperature distribution) was obtained by irradiating a heat-resistant block with various lasers and measuring the block surface using a thermal imager. The results are shown in Fig. 9 .

[0064] like Fig. 9 As shown, the temperature of the portion irradiated by the laser irradiation device 2 is high, while the temperature of the portion irradiated by the laser irradiation devices 1 and 3 is low. Based on this result, it can be considered that by adjusting the average energy density of the heat source irradiated to the center and the end, the drying time of the center and the end can be adjusted to be the same.

Claims

1. A method for manufacturing an electrode, comprising: a coating step of coating a slurry obtained by dispersing an electrode material in a solvent on the collector foil to obtain a coating film; and a drying step of drying the coating film while conveying the collector foil having the coating film formed thereon in a drying furnace; The coating film has three regions divided along the conveying direction, namely, a central portion arranged at the center in the width direction, and end portions arranged at both sides of the central portion, respectively. The drying step dries the end portions of the coating film using a heat source having a low energy density, and dries the center portion of the coating film using a heat source having a high energy density.

2. The method for manufacturing an electrode according to claim 1, wherein: In the drying process, the heat source with low energy density is hot air or laser, and the heat source with high energy density is laser.

3. The method for manufacturing an electrode according to claim 2, wherein: When the sum of average energy densities of heat sources irradiated to the center of the coating film is defined as EC, and the sum of average energy densities of heat sources irradiated to the ends of the coating film is defined as EE, EC / EE calculated based on the following formula is 1 or more and 4 or less, (Laser average energy density (W / cm 2 ))=(Laser energy density (W / cm 2 ))÷(laser irradiation length in the conveying direction (mm))×(total length of the drying furnace in the conveying direction (mm)), (Average energy density of hot air (W / cm 2 ))=(Laser average energy density (W / cm 2 ))×(time (s) when the coating film is dried only by laser)÷(time (s) when the coating film is dried only by hot air).

4. The method for manufacturing an electrode according to any one of claims 1 to 3, wherein: When the endmost portion in the width direction of the coating film is defined as the starting point, the end portion of the coating film is a region extending from 3 mm to 18 mm inward in the width direction from the starting point.

5. The method for manufacturing an electrode according to any one of claims 1 to 3, wherein: The length of the coating film in the width direction is 1000 mm or more and 1500 mm or less.

6. A method for manufacturing a battery, comprising: An electrode manufacturing step, using the electrode manufacturing method according to any one of claims 1 to 3 to obtain an electrode; and The battery manufacturing process uses the electrodes to assemble the battery.

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