Electrode manufacturing method
A two-step drying process using laser and hot air/IR in controlled furnaces addresses the high energy consumption issue in electrode manufacturing, enhancing productivity and moisture removal efficiency.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- TOYOTA JIDOSHA KK
- Filing Date
- 2023-09-14
- Publication Date
- 2026-05-26
AI Technical Summary
Conventional electrode manufacturing methods require high energy consumption to achieve absolute drying of moisture, leading to low productivity due to the need for blowing low-dew-point hot air into the entire furnace.
A two-step drying process involving laser drying followed by drying with hot air or IR, with controlled pressure, temperature, and dew point conditions in separate furnaces, to efficiently remove moisture from the electrode layer.
Improves productivity by reducing energy consumption and ensuring effective moisture removal, maintaining a stable drying environment.
Smart Images
Figure 0007865299000001
Abstract
Description
[Technical Field]
[0001] This disclosure relates to a method for manufacturing electrodes. [Background technology]
[0002] Various techniques have been proposed regarding the manufacturing method of electrodes, such as the one disclosed in Patent Document 1. [Prior art documents] [Patent Documents]
[0003] [Patent Document 1] Japanese Patent Publication No. 2020-145034 [Overview of the Initiative] [Problems that the invention aims to solve]
[0004] Conventional technology involves coating and drying, pressing, and baking (absolute drying) in order to suppress the springback of electrodes, where residual stress from press working is released over time, increasing the electrode thickness. However, achieving absolute drying of electrode moisture (below 500 ppm) requires blowing low-dew-point hot air into the entire furnace, resulting in high energy consumption (low productivity).
[0005] This disclosure is made in view of the above circumstances and primarily aims to provide a method for manufacturing electrodes that can improve productivity. [Means for solving the problem]
[0006] In a first embodiment of this disclosure, a method for manufacturing an electrode is described, Forming step, which involves forming an electrode layer on a substrate, The process includes a drying step for drying the electrode layer, The drying process described above is The first step is to dry the electrode layer with a laser, The present invention provides a method for manufacturing an electrode, comprising 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 this disclosure, in the first embodiment, the pressure in the first furnace in the first step may be less than the pressure in the second furnace in the second step.
[0008] In a third embodiment of this 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 this disclosure, in the second embodiment, the volume of the first furnace may be greater than the volume of the second furnace.
[0010] In a fifth embodiment of this disclosure, in the second embodiment, the dew point in the second furnace may be -20°C or lower. [Effects of the Invention]
[0011] The electrode manufacturing method of this disclosure can improve productivity. [Brief explanation of the drawing]
[0012] [Figure 1] This is a schematic diagram illustrating an example of the drying process in this disclosure. [Modes for carrying out the invention]
[0013] Embodiments of this disclosure are described below. Matters other than those specifically mentioned herein but necessary for the implementation of this disclosure (e.g., general configuration and manufacturing processes of electrodes not characterizing this disclosure) can be understood as design matters for those skilled in the art based on the prior art. This disclosure can be implemented based on the content disclosed herein and common technical knowledge in the art. Furthermore, the dimensions (length, width, thickness, etc.) shown in the diagram do not necessarily reflect the actual dimensions.
[0014] In the present disclosure, a method for manufacturing an electrode includes: a forming step of forming an electrode layer on a substrate; a drying step of drying the electrode layer, and 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. A method for manufacturing an electrode is provided.
[0015] Since the laser is only absorbed by the member, the space temperature remains at room temperature and the drying state is not good. The present researcher has found that it is important to combine the temperature increase of the electrode layer by laser irradiation and the temperature increase of the space temperature by at least one of hot air and IR in the baking (absolute drying) treatment of the electrode layer. It has also been 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 absolutely drying the electrode layer can be improved.
[0016] (1) Forming step 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 the material of 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 shape or the like.
[0018] The electrode layer is formed by coating an electrode slurry on the first surface of the substrate. The electrode slurry may be coated only on the first surface of the current collector, or may be coated on the first surface of the current collector and the second surface which is the back surface of the first surface, and the electrode layer may be formed on both surfaces of the current collector. Electrode slurry can be prepared by mixing electrode materials, including active material, binder, conductive material, electrolyte, thickener, etc., with a solvent. The electrode slurry may be a positive electrode slurry or a negative electrode slurry. The electrode slurry may contain a moisture content of about 10,000 ppm or less. The electrode slurry coated onto the substrate may be dried and pressed to form an electrode layer.
[0019] The active material may also be the positive electrode active material. Examples of positive electrode active materials include oxide active materials. Examples of oxide active materials include LiCoO2, LiMnO2, LiNiO2, LiVO2, and LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 Rock salt layered active materials such as O2, LiMn2O4, Li(Ni 0.5 Mn 1.5 Examples include spinel-type active materials such as O4, and olivine-type active materials such as LiFePO4, LiMnPO4, LiNiPO4, and LiCuPO4.
[0020] The active material may also be the negative electrode active material. Examples of negative electrode active materials include carbon active materials, oxide active materials, and metal active materials. Examples of carbon active materials include mesocarbon microbeads (MCMB), highly oriented graphite (HOPG), hard carbon, and soft carbon. Examples of oxide active materials include Nb2O5 and Li4Ti5O 12 Examples of metal active materials include SiO. Examples of metal active materials include In, Al, Si, and Sn.
[0021] Examples of binders 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 the conductive material include carbon materials, metal particles, conductive polymers, etc. Examples of the carbon materials include particulate carbon materials such as acetylene black (AB) and ketjen black (KB); fibrous carbon materials such as carbon fibers, carbon nanotubes (CNT), and carbon nanofibers (CNF).
[0023] Examples of the thickener include polysaccharides such as carboxymethyl cellulose and methyl cellulose.
[0024] Examples of the electrolyte include solid electrolytes such as sulfide solid electrolytes and oxide solid electrolytes. Examples of the sulfide solid electrolytes include solid electrolytes containing Li element, X element (X is at least one of P, As, Sb, Si, Ge, Sn, B, Al, Ga, In), and S element. Further, the sulfide solid electrolyte may further contain at least one of O element and halogen element. Examples of the halogen element include F element, Cl element, Br element, and I element.
[0025] Examples of the 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 Si 0.6 P 0.4 O4, Li4SiO4, Li3PO4, Li3PO 4-3 / 2x N x (x ≤ 1).
[0026] Examples of the solvent include aqueous solvents, organic solvents, etc. 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 according to the types of active materials, binders, etc. As an aqueous solvent, water is preferably used due to its ease of handling. Examples of polar organic solvents that can be used as a mixed solvent include alcohols such as methanol, ethanol, and isopropyl alcohol, ketones such as acetone, and ethers such as tetrahydrofuran. Examples of organic solvents include N-methyl-2-pyrrolidone (NMP).
[0027] (2) Drying process The drying step is a step of drying the electrode layer. Typically, a drying device is used in the drying process to dry the electrode layer. The drying device can be any conventionally known device capable of drying the electrode layer, such as a hot air device, a laser device, or an IR (infrared) device. In the drying process, 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 process includes a first step and a second step. The first step is to dry the electrode layer using a laser. The second step is to dry the electrode layer after the first drying step using at least one of hot air and IR. In the first step, the electrode layer may be dried in the first furnace, and in the second step, the electrode layer may be dried in the second furnace. In the drying step, the workpiece including the substrate and the electrode layer formed on the substrate may be placed on a conveyor and transported in the order of the first furnace and then the second furnace. Alternatively, the workpiece may be placed on a conveyor and transported in the order of the forming step and then the drying step. The transport speed may be, for example, 30 m / min or more.
[0029] The dew point in the second furnace (second dew point) may be lower than the dew point in the first furnace (first dew point). The first dew point may be above -20°C. The second dew point may be below -20°C.
[0030] The pressure in the first furnace during the first process may be lower than the pressure in the second furnace during the second process. This suppresses the generation of airflow from the first furnace to the second furnace, and allows the dew point of the second furnace to remain lower than that of the first furnace. The pressure inside the first furnace in the first process may be negative relative to the outside of the drying process system, and may also be negative relative to the pressure inside the second furnace in the second process. The pressure inside the second furnace in the second process may be positive relative to the pressure inside the first furnace in the first process, and negative relative to the outside of the drying process 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 inside the second furnace can be lowered.
[0032] In the first step, the electrode layer may be dried using a laser device. In the first step, in addition to the laser device, a hot air device, an IR device, etc., may be used in combination to dry the electrode layer. In the first step, outside air may be supplied into the first furnace, or hot air with a dew point of -20°C to 25°C and a temperature of 65°C or higher may be supplied to raise the temperature inside the first furnace to 65°C or higher. In the first step, taking advantage of the fact that the pressure inside the first furnace is lower than the pressure inside the second furnace, hot air may be supplied into the second furnace, an airflow may be generated so that the hot air flows from the second furnace to the first furnace, and the hot air supplied to the second furnace may be supplied into the first furnace. This makes it possible to suppress the rise in the dew point inside 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 required for drying the electrode layer, and the heating temperature of the electrode layer may be between 100°C and 200°C. The drying time of the electrode layer in the first step can be set appropriately according to the dew point, temperature, heating temperature of the electrode layer, etc. in the first furnace. In the first step, the electrode layer may be dried using a laser and IR at a temperature of 100°C to 200°C for 10 to 15 seconds.
[0033] In the second step, the electrode layer is dried using at least one of hot air and IR. In the second step, the electrode layer may be dried using a laser device in addition to a hot air device and an IR device. In the second step, radiant heat may be used. The temperature inside the second furnace in the second step may be 65°C or higher. In the second step, hot air, for example, air with a dew point of -20°C or lower and a temperature of 65°C or higher, may be supplied to the second furnace to raise the temperature inside the second furnace to 65°C or higher. The temperature of the hot air supplied to the second furnace in the second process may be the same as or higher than the temperature of the hot air supplied to the first furnace in the first process, or it may be a temperature higher than the temperature reached by the electrode layer, from the viewpoint of suppressing a decrease in the temperature of the electrode layer. In the second step, the electrode layer may be dried using a laser or IR at a temperature of 100°C to 200°C for 10 to 15 seconds. The drying time for the electrode layer in the second step can be set appropriately according to the dew point and temperature in the second furnace, the heating temperature of the electrode layer, etc.
[0034] The dew point at the outlet of the second furnace in the second step may be -20°C or lower. The area on the outlet side after leaving the second furnace may be a dry air atmosphere. In the second step, moisture is removed from the electrode layer to a level of several hundred ppm or less, for example, 500 ppm or less, the electrode layer is completely dried, and the electrode of the present disclosure is obtained.
[0035] The dew point fluctuates when outside air flows into the furnace or when the moisture in the electrode layer itself dries. Therefore, in the drying process, a dew point meter may be installed, and in an environment where hot air is supplied, the dew point of the air, the amount of hot air supplied, and the temperature of the hot air may be adjusted as appropriate according to the measured dew point. Specifically, the dew point meter may be installed in the exhaust piping of the second reactor. The dew point of the exhaust piping may then be fed back to the supply air side, and the dew point of the air, the amount of hot air supplied, and the temperature of the hot air may be adjusted so that the dew point value reaches a predetermined dew point. Even if the internal furnace environment fluctuates due to the evaporation of moisture from the electrode layer, the dew point, hot air supply rate, hot air temperature, etc., can be adjusted to follow these changes, thereby ensuring stable drying of the electrode layer. Instead of adjusting the dew point, hot air supply rate, and hot air temperature for all furnaces from the first to the second, the most efficient way to completely dry the electrode layer is to observe and control the dew point of the second furnace, which is the final zone. To adjust the amount of hot air supplied, an auto damper or the like, which can control opening and closing and the degree of opening according to the dew point, may be used.
[0036] Figure 1 is a schematic diagram showing an example of the drying process of this disclosure. In the drying process shown in Figure 1, the workpiece 1 is transported in the transport direction, in the first step the workpiece 1 is heated in the first furnace 10 by a laser device 11, and in the second step hot air 50 is supplied into the second furnace 20 by a hot air device 21, and the workpiece 1 is heated by the hot air 50. In the second step, an IR device or the like may be used instead of the hot air device 21. 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. Because the pressure inside the first furnace 10 is lower than the pressure inside the second furnace 20, the hot air 50 supplied to the second furnace 20 generates an airflow that flows from the second furnace 20 into the first furnace 10, and the second dew point inside the second furnace 20 is maintained to be lower than the first dew point inside the first furnace 10. The area on the outlet side of the second furnace 20 after the second process may be under a dry air atmosphere.
[0037] The electrode obtained by the manufacturing method of this disclosure comprises an electrode layer and a current collector. The electrode layer may be either a positive electrode layer or a negative electrode layer. The electrode layer may also contain a positive electrode active material and a negative electrode active material, as well as a binder, conductive material, 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, thickness, and shape of the current collector are as described above.
[0038] The electrodes of this disclosure are typically used in the manufacture of batteries. The electrodes may be positive or negative electrodes. The type of battery using electrodes is not particularly limited, but lithium-ion secondary batteries are an example. The battery may be a liquid-type battery using an electrolyte solution, or a solid-state battery using a solid electrolyte solution. Applications of the battery include, for example, powering vehicles such as hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), battery electric vehicles (BEVs), gasoline cars, and diesel cars. In particular, it may be used as a power source for hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), or electric vehicles (BEVs). The battery may also be used as a power source for mobile devices other than vehicles (e.g., trains, ships, aircraft), or as a power source for electrical products such as information processing devices. [Explanation of symbols]
[0039] 1. Work 10.First furnace 11. Laser device 20.Second Furnace 21.Hot air device 50. Hot air
Claims
1. A method for manufacturing electrodes, Forming step, which involves forming an electrode layer on a substrate, The process includes a drying step of drying the electrode layer until the moisture content is 500 ppm or less. The aforementioned drying process is The first step involves drying the electrode layer with a laser and hot air. The process includes a second step of drying the electrode layer with hot air and IR after the first step, The pressure inside the first furnace in the first step is less than the pressure inside the second furnace in the second step. The temperatures inside the first furnace and the second furnace are 65°C or higher. A method for manufacturing electrodes, wherein the dew point in the first furnace is between -20°C and 25°C, and the dew point in the second furnace is below -20°C.
2. The method for manufacturing an electrode according to claim 1, wherein the volume of the first furnace is greater than the volume of the second furnace.