Manufacturing method of electrode

Abstract

To provide a manufacturing method of an electrode capable of improving the productivity.SOLUTION: A manufacturing method of an electrode includes: a coating step of coating a base material with electrode slurry; an electrode mixture layer formation step of drying the electrode slurry, and forming an electrode mixture layer; a press step of pressing the electrode mixture layer on the base material; a first dry step of drying the electrode mixture layer under a first dew point; a second dry step of drying the electrode mixture layer under a second dew point that is lower than the first dew point after the first dry step; and a third dry step of drying the electrode mixture layer under a third dew point that is lower than the second dew point after the second dry step. The press step and the first dry step are executed in the same first section, and the first section of the first dry step, a second section of the second dry step, and a third section fo the third dry step are connected.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] Conventional techniques have 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] That is, the present disclosure includes the following aspects. <1> 1. A method for manufacturing an electrode, comprising: a coating step of coating an electrode slurry on a substrate; an electrode mixture layer forming step of drying the electrode slurry to form an electrode mixture layer; a pressing step of pressing the electrode mixture layer on the substrate; a first drying step of drying the electrode mixture layer at a first dew point; a second drying step of drying the electrode mixture layer at a second dew point lower than the first dew point after the first drying step; and a third drying step of drying the electrode mixture layer at a third dew point lower than the second dew point after the second drying step, wherein the pressing step and the first drying step are performed in the same first section, and the first section of the first drying step, the second section of the second drying step, and the third section of the third drying step are connected to each other. Effect of the Invention

[0007] The electrode manufacturing method of the present disclosure can improve productivity. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of the manufacturing method of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] 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.

[0010] The present disclosure provides a method for producing an electrode, the method including: a coating step of coating an electrode slurry on a substrate; an electrode mixture layer forming step of drying the electrode slurry to form an electrode mixture layer; a pressing step of pressing the electrode mixture layer on the substrate; a first drying step of drying the electrode mixture layer at a first dew point; a second drying step of drying the electrode mixture layer at a second dew point lower than the first dew point after the first drying step; and a third drying step of drying the electrode mixture layer at a third dew point lower than the second dew point after the second drying step, wherein the pressing step and the first drying step are performed in the same first section, and the first section of the first drying step, the second section of the second drying step, and the third section of the third drying step are connected.

[0011] In the present disclosure, the electrode mixture layer can be subjected to an absolute drying treatment while suppressing an increase in the thickness of the electrode mixture layer, thereby improving the drying efficiency of the electrode mixture layer and improving the productivity of the electrode.

[0012] (1) Coating process The coating step is a step of coating the electrode slurry onto a substrate. 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.

[0013] The electrode slurry is applied to a first surface of the substrate. The electrode slurry may be applied only to the first surface of the substrate, or may be applied to the first surface and a second surface opposite to the first surface of the substrate. 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 method for applying the electrode slurry to the substrate is not particularly limited, and any conventionally known method can be used.

[0014] (2) Electrode composite layer formation process The electrode mixture layer forming step is a step of drying the electrode slurry to form an electrode mixture layer. A drying device may be used to dry the electrode slurry. The drying device may be a conventionally known device capable of drying the electrode slurry, such as a hot air device, a laser device, or an IR (infrared) device, and these may be used in combination. The drying temperature of the electrode slurry may be 100° C. to 200° C. The drying time of the electrode slurry is not particularly limited.

[0015] (3) Pressing process The pressing step is a step of pressing the electrode mixture layer on the substrate. Examples of the method for pressing the electrode mixture layer include roll pressing and hot pressing. (4) First drying process The first drying step is a step of drying the electrode mixture layer at a first dew point or below. (5)Second drying process The second drying step is a step of drying the electrode mixture layer at a second dew point lower than the first dew point after the first drying step. (6)Third drying process The third drying step is a step of drying the electrode mixture layer at a third dew point lower than the second dew point after the second drying step.

[0016] The pressing step and the first drying step are carried out in the same first section. The first section of the first drying step, the second section of the second drying step, and the third section of the third drying step are connected to each other. In the first drying step, the electrode mixture layer may be dried in the first section, in the second drying step, the electrode mixture layer may be dried in the second section, and in the third drying step, the electrode mixture layer may be dried in the third section. In the first to third drying steps, a work including a substrate and an electrode mixture layer obtained by drying the electrode slurry applied to the substrate may be placed on a conveyor and conveyed in the order of the first section, the second section, and the third section. In addition, the work may be placed on the conveyor and conveyed in the order of the coating step, the electrode mixture layer forming step, and the pressing step. The conveying speed may be, for example, 30 m / min or more. In the first section, the electrode mixture layer is pressed and dried, in the second section, the dew points of the first section and the third section are separated, and in the third section, the electrode mixture layer may be completely dried (baked). The first section may be provided with an exhaust hole. The first zone may be general air conditioning, and the second zone and the third zone may be dry air conditioning.

[0017] The second dew point is lower than the first dew point, and the third dew point is lower than the second dew point. The first dew point may be -20° C. or higher, or may be -10° C. or higher. The second dew point may be lower than the first dew point and higher than the third dew point, for example, -10° C. or lower. The third dew point may be -20° C. or lower.

[0018] The pressure in the first section in the first drying step may be lower than the pressure in the second section in the second drying step, and the pressure in the second section in the second drying step may be lower than the pressure in the third section in the third drying step, thereby suppressing the generation of an airflow from the first section to the second section and suppressing the generation of an airflow from the second section to the third section, and making it possible to maintain a state in which the dew points in the second and third sections are lower than the dew point in the first section. The pressure in the second section in the second drying step may be positive with respect to the pressure in the first section in the first drying step, and may be negative with respect to the pressure in the third section in the third drying step. The pressure in the third zone in the third drying step may be negative with respect to the outside of the third drying step system, and may be positive with respect to the pressure in the second zone in the second drying step.

[0019] The volume of the first section may be larger than the volumes of the second and third sections. By making the volumes of the second and third sections smaller than the volume of the first section, the dew point of the air can be lowered after the second drying step. The volumes of the second and third sections may be the same or different.

[0020] In the first drying step, the electrode mixture layer may be heated using a hot air device, a laser device, an IR device, or the like. In the first drying step, outside air may be supplied into the first section, or air having a temperature of, for example, 65°C or higher may be supplied as hot air. In the first drying step, the pressure in the first section is smaller than the pressure in the second section, so that hot air is supplied into the second section, an airflow is generated so that the hot air flows from the second section into the first section, and the hot air supplied into the second section is supplied into the first section. This makes it possible to suppress an increase in the dew point in the second section. In the first drying step, radiant heat may be used. In the first drying step, the electrode mixture layer may be heated to the maximum temperature required for drying the electrode mixture layer, and the heating temperature of the electrode mixture layer may be 100°C to 200°C. The drying time for the electrode mixture layer in the first drying step is not particularly limited. The drying time of the electrode mixture layer in the first drying step can be appropriately set depending on the dew point and temperature in the first zone, the heating temperature of the electrode mixture layer, and the like.

[0021] In the second drying step, for example, air with a dew point of -10°C or less and a temperature of 65°C or more may be supplied as hot air into the second zone, and the temperature in the second zone may be 65°C or more. In the second drying step, the pressure in the first zone is lower than the pressure in the second zone, and the pressure in the second zone is lower than the pressure in the third zone, so that hot air is supplied into the third zone, an airflow is generated so that hot air flows from the third zone into the second zone and the first zone, and the hot air supplied into the third zone may be supplied into the second zone and the first zone. This makes it possible to suppress an increase in the dew point in the third zone. In the second drying step, by providing the second zone, the first zone and the third zone are isolated, and the third zone can be maintained at a low dew point. The drying time for the electrode mixture layer in the second drying step is not particularly limited.

[0022] In the third drying step, hot air having a dew point of -20°C or less and a temperature of 65°C or more may be supplied into the third zone to set the temperature in the third zone to 65°C or more. In the third drying step, the electrode mixture layer may be heated using a hot air device, a laser device, an IR device, or the like. In the third drying step, radiant heat may be used. The heating temperature of the electrode mixture layer in the third drying step may be 100°C to 200°C. The temperature of the hot air supplied within the third section in the third drying step may be the same as or higher than the temperature of the hot air supplied within the first section in the first drying step, from the viewpoint of suppressing a decrease in the temperature of the electrode mixture layer, and may be a temperature higher than the temperature reached by the electrode mixture layer. The drying time for the electrode mixture layer in the third drying step is not particularly limited. In the third drying step, the electrode mixture layer may be dried by 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.

[0023] The dew point at the outlet of the third section in the third drying step may be -20°C or lower. The area on the outlet side after leaving the third section may be in a dry air atmosphere. The third drying step may remove moisture from the electrode mixture layer until the moisture content is several hundred ppm or less, for example, 500 ppm or less.

[0024] FIG. 1 is a schematic diagram showing an example of the manufacturing method of the present disclosure. The work 1 shown in FIG. 1 includes a substrate and an electrode mixture layer formed by applying an electrode slurry onto the substrate in a coating step and drying the electrode slurry in an electrode mixture layer forming step. As shown in FIG. 1, the work 1 is conveyed in the conveying direction, and in the pressing step and the first drying step, the work 1 is heated by hot air 50 while being pressed by a roll press 11 in the first section 10. An exhaust hole 60 is provided in the first section 10, and the hot air 50 flowing from the second section 20 is exhausted to the outside of the first section 10. In the second drying step, the hot air 50 is supplied into the second section 20 by the hot air device 21, and in the third step, the hot air 50 is supplied into the third section 30 by the hot air device 32, and the work 1 is heated by a laser device 31 in the third section 30. A partition 70 may be provided separating the first section 10 and the second section 20 . In the second drying step, the hot air 50 supplied from the hot air device 21 may have a dew point of -10°C or lower and a temperature of 65°C or higher. In the third drying step, the hot air 50 supplied from the hot air device 32 may have a dew point of -20°C or lower and a temperature of 65°C or higher. The volumes of the second section 20 and the third section 30 are smaller than the volume of the first section 10. Because the pressure in the first section 10 is smaller than the pressure in the second section 20, an airflow is generated such that the hot air 50 supplied into the second section 20 flows from the second section 20 into the first section 10, and the second dew point in the second section 20 is maintained lower than the first dew point in the first section 10. Because the pressure in the second section 20 is lower than the pressure in the third section 30, an airflow is generated such that the hot air 50 supplied into the third section 30 flows from the third section 30 into the second section 20, and the third dew point in the third section 30 is maintained lower than the second dew point in the second section 20. With a compact configuration in which the heat source is directly connected to the press, the electrode mixture layer is efficiently heated by radiant heat after pressing, the hot air 50 in the third section 30 is not leaked outside, and the general dew point air in the first section 10 is not brought into the third section 30, so that an increase in the thickness of the electrode mixture layer can be suppressed and moisture can be efficiently removed.

[0025] Table 1 shows the results of investigating the tendency of the electrode mixture layer to return to its original thickness after being pressed under various heating conditions using an electrode mixture layer containing graphite as an active material having a predetermined density. As shown in Table 1, when stored at room temperature, it takes about a week for the thickness to return to its original state and stabilize. When using a hot roll press (transport speed: approximately 40 m / min), the time it takes to pass through the electrode mixture layer is too short to raise the temperature sufficiently, and the increase in the thickness of the electrode mixture layer cannot be restored. It is possible to raise the temperature by increasing the roll temperature, but this will be inefficient relative to the required temperature. In the case of hot plate heating, the electrode mixture layer can be heated in a relatively short time and the thickness of the electrode mixture layer can be restored, but it takes time for heat transfer. The laser can rapidly increase the temperature and return the electrode mixture layer thickness to its original thickness in a short time, and it is found that the return tendency of the electrode mixture layer thickness is efficiently achieved by the laser. Therefore, the combination of the hot roll press and the laser can improve productivity.

[0026] [Table 1]

[0027] The electrode obtained by the manufacturing method of the present disclosure includes a current collector and an electrode mixture layer formed by drying an electrode slurry applied to at least one surface of the current collector. The electrodes of the present disclosure are typically used in the manufacture of batteries. The electrodes may be positive, negative, or bipolar electrodes. A bipolar electrode comprises a positive electrode mixture layer on one side of a current collector and a negative electrode mixture layer on the other side of the current collector. 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]

[0028] 1. Work 10. First Section 11.Roll press 20. Second Section 21.Hot air device 30. Third Section 31. Laser equipment 32.Hot air device 50. Hot air 60. Exhaust vent 70. Partition

Claims

[Claim 1] A method for manufacturing an electrode, comprising the steps of: A coating step of coating the electrode slurry on a substrate; an electrode mixture layer forming step of drying the electrode slurry to form an electrode mixture layer; a pressing step of pressing the electrode mixture layer on the substrate; A first drying step of drying the electrode mixture layer at a first dew point; a second drying step of drying the electrode mixture layer at a second dew point lower than the first dew point after the first drying step; A third drying step of drying the electrode mixture layer at a third dew point lower than the second dew point after the second drying step, The pressing step and the first drying step are carried out in the same first section, A method for manufacturing an electrode, wherein the first section of the first drying step, the second section of the second drying step, and the third section of the third drying step are connected to each other.

Images