Manufacturing method for electrode

Abstract

To provide a manufacturing method for an electrode that can improve productivity.SOLUTION: A manufacturing method for an electrode includes a forming step of forming an electrode layer on a base material, and a drying step of drying the electrode layer. The drying step includes a first step of drying the electrode layer with a laser, and a second step of drying the electrode layer with at least one of hot air or IR after the first step.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Various techniques have been proposed for producing electrodes such as those disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-145034 A Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional technology, in order to suppress springback of the electrode, which occurs when the residual stress from press processing is released over time and the electrode thickness increases, the processes are performed in the order of coating and drying, pressing, and baking (bone drying).However, when bone drying the electrode moisture (to below 500 ppm), it is necessary to blow hot air with a low dew point over the entire furnace, which consumes a lot of energy (low productivity).

[0005] The present disclosure has been made in consideration of the above-mentioned circumstances, and has as its main object to provide a method for manufacturing an electrode that can improve productivity. [Means for solving the problem]

[0006] In a first embodiment of the present disclosure, there is provided a method for producing an electrode, comprising the steps of: A forming step of forming an electrode layer on a substrate; A drying step of drying the electrode layer, The drying step includes: A first step of drying the electrode layer by a laser; and a second step of drying the electrode layer with at least one of hot air and IR after the first step.

[0007] In a second embodiment of the present disclosure, in the first embodiment, the pressure in the first furnace in the first step may be lower than the pressure in the second furnace in the second step.

[0008] In the third embodiment of the present disclosure, in the second embodiment, the temperature in the second furnace in the second step may be 65° C. or higher.

[0009] In a fourth embodiment of the present disclosure, in the second embodiment, the volume of the first furnace may be larger than the volume of the second furnace.

[0010] In the fifth embodiment of the present disclosure, in the second embodiment, the dew point in the second furnace may be −20° C. or lower. Effect of the Invention

[0011] The electrode manufacturing method of the present disclosure can improve productivity. [Brief description of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic diagram showing an example of a drying step according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present disclosure will be described. Note that matters other than those specifically mentioned in this specification and necessary for implementing the present disclosure (for example, the general configuration and manufacturing process of the electrode that do not characterize the present disclosure) can be understood as design matters of a person skilled in the art based on the prior art in the field. The present disclosure can be implemented based on the contents disclosed in this specification and the technical common sense in the field. Furthermore, the dimensional relationships (length, width, thickness, etc.) in the drawings do not reflect the actual dimensional relationships.

[0014] The present disclosure provides a method for producing an electrode, comprising the steps of: A forming step of forming an electrode layer on a substrate; A drying step of drying the electrode layer, The drying step includes: A first step of drying the electrode layer by a laser; and a second step of drying the electrode layer with at least one of hot air and IR after the first step.

[0015] Since the laser is only absorbed by the material, the temperature in the space remains at room temperature, and the drying condition is not good. The researchers found that it is important to combine raising the temperature of the electrode layer by laser irradiation and raising the temperature of the space by at least one of hot air and IR in the baking (bone drying) process of the electrode layer. They also found that by lowering the dew point, the electrode layer can be dried at a low space temperature. In the present disclosure, the productivity in the step of bone-drying the electrode layer can be improved.

[0016] (1) Formation process The forming step is a step of forming an electrode layer on a substrate.

[0017] The substrate may be a current collector or the like. The current collector may be a negative electrode current collector, a positive electrode current collector, a bipolar current collector, or the like. Examples of materials for the current collector include metals such as aluminum, copper, SUS, and nickel. The thickness of the current collector is, for example, 0.1 μm or more and 100 μm or less. The shape of the current collector may be a sheet or the like.

[0018] The electrode layer is formed by applying an electrode slurry to a first surface of the substrate. The electrode slurry may be applied only to the first surface of the current collector, or may be applied to the first surface of the current collector and a second surface opposite to the first surface, and the electrode layer may be formed on both surfaces of the current collector. The electrode slurry can be prepared by mixing electrode materials including an active material, a binder, a conductive material, an electrolyte, a thickener, and the like, together with a solvent. The electrode slurry may be a positive electrode slurry or a negative electrode slurry. The electrode slurry may contain water of about 10,000 ppm or less. The electrode slurry applied onto the substrate may be dried and pressed to form an electrode layer.

[0019] The active material may be a positive electrode active material. Examples of the positive electrode active material include oxide active materials. Examples of the oxide active material include LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2, etc., rock salt layered active materials, LiMn2O4, Li(Ni 0.5 Mn 1.5 )O4 and the like; and olivine type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4.

[0020] The active material may be a negative electrode active material. Examples of the negative electrode active material include carbon active materials, oxide active materials, and metal active materials. Examples of the carbon active material include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. Examples of the oxide active material include Nb2O5, Li4Ti5O 12 and SiO. Examples of the metal active material include In, Al, Si, Sn, and the like.

[0021] Examples of the binder include fluorine-containing binders such as polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE), rubber-based binders such as butadiene rubber, and acrylic-based binders.

[0022] Examples of conductive materials include carbon materials, metal particles, conductive polymers, etc. Examples of carbon materials include particulate carbon materials such as acetylene black (AB) and ketjen black (KB), and fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF).

[0023] Examples of thickeners include polysaccharides such as carboxymethylcellulose and methylcellulose.

[0024] Examples of the electrolyte include solid electrolytes such as sulfide solid electrolytes and oxide solid electrolytes. Examples of the sulfide solid electrolyte include solid electrolytes containing Li, X (X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, and In), and S. The sulfide solid electrolyte may further contain at least one of O and halogen elements. Examples of the halogen elements include F, Cl, Br, and I.

[0025] Examples of oxide solid electrolytes include Li2O-B2O3-P2O5, Li2O-SiO2, Li2O-B2O3, Li 1.3 Al 0.3 Ti 0.7 (PO4)3, Li5La3Ta2O 12 , Li7La3Zr2O 12 , Li6BaLa2Ta2O 12 , Li 3.6 S 0.6 P 0.4 O4, Li4SiO4, Li3PO4, Li3PO 4-3 / 2x N x (x≦1).

[0026] Examples of the solvent include aqueous solvents and organic solvents. The aqueous solvent means water or a mixed solvent containing water and a polar organic solvent. For example, an appropriate dispersion medium can be selected depending on the types of active material, binder, etc. As the aqueous solvent, water is preferably used because of its ease of handling. Examples of polar organic solvents that can be used in the mixed solvent include alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone, and ethers such as tetrahydrofuran. An example of the organic solvent is N-methyl-2-pyrrolidone (NMP).

[0027] (2) Drying process The drying step is a step of drying the electrode layer. In general, in the drying step, a drying device is used to dry the electrode layer. The drying device may be a conventional device capable of drying the electrode layer, such as a hot air device, a laser device, or an IR (infrared) device. In the drying step, the electrode layer may be completely dried until the moisture content is several hundred ppm or less, for example, 500 ppm or less.

[0028] The drying step includes a first step and a second step. The first step is to dry the electrode layer by using a laser. The second step is a step of drying the electrode layer with at least one of hot air and IR after the first drying step. In the first step, the electrode layer may be dried in a first furnace, and in the second step, the electrode layer may be dried in a second furnace. In the drying step, a workpiece including a substrate and an electrode layer formed on the substrate may be placed on a carrier and transported to the first furnace and then the second furnace. Also, the workpiece may be placed on a carrier and transported in the forming step and drying step in that order. The transport speed may be, for example, 30 m / min or more.

[0029] The dew point in the second furnace (the second dew point) may be lower than the dew point in the first furnace (the first dew point). The first dew point may be greater than or equal to −20° C. The second dew point may be less than or equal to −20° C.

[0030] The pressure in the first furnace in the first step may be lower than the pressure in the second furnace in the second step, thereby suppressing the generation of an air flow from the first furnace to the second furnace, and making it possible to maintain a state in which the dew point of the second furnace is lower than the dew point of the first furnace. The pressure in the first furnace in the first step may be negative relative to the pressure outside the drying process system, and may also be negative relative to the pressure in the second furnace in the second step. The pressure in the second furnace in the second step may be a positive pressure relative to the pressure in the first furnace in the first step, and may also be a negative pressure relative to the outside of the drying step system.

[0031] The volume of the first furnace may be larger than the volume of the second furnace. By making the volume of the second furnace smaller than the volume of the first furnace, the dew point in the second furnace can be lowered.

[0032] In the first step, the electrode layer may be dried by a laser using a laser device. In the first step, the electrode layer may be dried by using a hot air device, an IR device, or the like in addition to the laser device. In the first step, outside air may be supplied into the first furnace, or air with a dew point of -20°C or more and 25°C or less and a temperature of 65°C or more may be supplied as hot air to set the temperature in the first furnace to 65°C or more. In the first step, the pressure in the first furnace is smaller than the pressure in the second furnace, so that hot air is supplied into the second furnace, an air flow is generated so that the hot air flows from the second furnace into the first furnace, and the hot air supplied into the second furnace may be supplied into the first furnace. This makes it possible to suppress an increase in the dew point in the second furnace. In the first step, radiant heat may be used. In the first step, the electrode layer may be heated to the maximum temperature necessary for drying the electrode layer, and the heating temperature of the electrode layer may be 100°C to 200°C. The drying time of the electrode layer in the first step can be appropriately set depending on the dew point and temperature in the first furnace, the heating temperature of the electrode layer, and the like. In the first step, the electrode layer may be dried using a laser, IR, or the like under conditions of a temperature of 100° C. to 200° C. and a time period of 10 to 15 seconds.

[0033] In the second step, the electrode layer is dried by at least one of hot air and IR. In the second step, the electrode layer may be dried by using a laser device in addition to the hot air device and the IR device. In the second step, radiant heat may be used. The temperature in the second furnace in the second step may be 65°C or higher. In the second step, air with a dew point of -20°C or lower and a temperature of 65°C or higher may be supplied as hot air into the second furnace, and the temperature in the second furnace may be 65°C or higher. The temperature of the hot air supplied into the second furnace in the second step may be the same as or higher than the temperature of the hot air supplied into the first furnace in the first step, from the viewpoint of suppressing a decrease in the temperature of the electrode layer, and may be a temperature higher than the temperature reached by the electrode layer. In the second step, the electrode layer may be dried using a laser, IR, or the like under conditions of a temperature of 100° C. to 200° C. and a time period of 10 to 15 seconds. The drying time of the electrode layer in the second step can be appropriately set depending on the dew point and temperature in the second furnace, the heating temperature of the electrode layer, and the like.

[0034] The dew point at the outlet of the second furnace in the second step may be -20°C or less. The area on the outlet side after leaving the second furnace may be in a dry air atmosphere. By the second step, moisture is removed from the electrode layer until the moisture is several hundred ppm or less, for example, 500 ppm or less, and the electrode layer is completely dried, thereby obtaining the electrode of the present disclosure.

[0035] The dew point varies when outside air flows into the furnace or when moisture in the electrode layer itself dries. Therefore, in the drying process, a dew point meter may be provided to appropriately adjust the dew point of the air, the amount of hot air supplied, and the temperature of the hot air according to the dew point actually measured in an environment in which air is supplied as hot air. Specifically, the dew point meter may be provided in the exhaust piping in the second furnace. The dew point of the exhaust piping may be fed back to the air supply side, and the dew point of the air, the amount of hot air supply, and the temperature of the hot air may be adjusted so that the dew point value becomes a predetermined dew point. Even if the environment inside the furnace fluctuates due to evaporation of moisture in the electrode layer, etc., the electrode layer can be stably dried by adjusting the dew point, hot air supply amount, hot air temperature, etc. to follow the changes. Rather than adjusting the dew point, hot air supply amount, hot air temperature, etc. for all of the first to second furnaces, the electrode layer can be most efficiently dried by observing and controlling the dew point of the second furnace, which is the final zone. The amount of hot air supplied may be adjusted using an auto-damper or the like whose opening / closing and opening degree can be controlled according to the dew point.

[0036] FIG. 1 is a schematic diagram showing an example of the drying step of the present disclosure. In the drying process shown in Figure 1, the workpiece 1 is transported in the transport direction, and in the first process, the workpiece 1 is heated by a laser device 11 in a first furnace 10, and in the second process, hot air 50 is supplied by a hot air device 21 into a second furnace 20, and the workpiece 1 is heated by the hot air 50. In the second step, instead of the hot air device 21, an IR device or the like may be used. In the second step, a partition may be provided between the first furnace 10 and the second furnace 20. In the second step, the hot air 50 supplied from the hot air device 21 may have a dew point of -20°C or lower and a temperature of 65°C or higher. The volume of the second furnace 20 is smaller than the volume of the first furnace 10. Since the pressure in the first furnace 10 is smaller than the pressure in the second furnace 20, the hot air 50 supplied to the second furnace 20 generates an airflow from the second furnace 20 to the first furnace 10, and the second dew point in the second furnace 20 is maintained lower than the first dew point in the first furnace 10. The area on the outlet side of the second furnace 20 after the second step may be in a dry air atmosphere.

[0037] The electrode obtained by the production method of the present disclosure comprises an electrode layer and a current collector. The electrode layer may be a positive electrode layer or a negative electrode layer. The electrode layer may contain one of a positive electrode active material and a negative electrode active material, and may further contain a binder, a conductive material, an electrolyte, etc. These materials are as described above. The current collector may be a negative electrode current collector, a positive electrode current collector, a bipolar current collector, etc. The material of the current collector, the thickness of the current collector, and the shape of the current collector are as described above.

[0038] The electrodes of the present disclosure are typically used in the manufacture of batteries. The electrodes may be positive or negative electrodes. The type of battery in which the electrode is used is not particularly limited, and may be, for example, a lithium ion secondary battery. The battery may be a liquid battery using an electrolytic solution as an electrolyte, or a solid battery using a solid electrolyte as an electrolyte. Examples of uses of the battery include power sources for vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), electric vehicles (BEVs), gasoline automobiles, and diesel automobiles. In particular, the battery may be used as a driving power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery may also be used as a power source for moving objects other than vehicles (for example, railways, ships, and aircraft), and may be used as a power source for electrical products such as information processing devices. [Explanation of symbols]

[0039] 1. Work 10.First furnace 11. Laser equipment 20.Second Furnace 21.Hot air device 50. Hot air

Claims

1. A method for manufacturing an electrode, comprising the steps of: A forming step of forming an electrode layer on a substrate; A drying step of drying the electrode layer, The drying step includes: A first step of drying the electrode layer by laser; a second step of drying the electrode layer by at least one of hot air and IR after the first step.

2. 2. The method for producing an electrode according to claim 1, wherein a pressure in the first furnace in the first step is lower than a pressure in the second furnace in the second step.

3. The method for producing an electrode according to claim 2 , wherein a temperature in the second furnace in the second step is 65° C. or higher.

4. The method for manufacturing an electrode according to claim 2 , wherein a volume of the first furnace is greater than a volume of the second furnace.

5. The method for producing an electrode according to claim 2 , wherein a dew point in the second furnace is −20° C. or lower.

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