Electrode manufacturing method

Abstract

To provide a manufacturing method of an electrode capable of suppressing over-drying of a coating liquid which is transferred into a drying furnace for the first time after a coating step is restarted.SOLUTION: A manufacturing method of an electrode includes a coating step Pr1 and a drying step. The drying step includes a first drying step and a second drying step Pr22. The first drying step is executed y operating a drying furnace 40 with such an air quantity and a temperature of a hot wind that a drying strength of the drying furnace 40 becomes a predetermined drying strength. The second drying step Pr22 is executed by operating the drying furnace 40 with such an air quantity and a temperature of the hot wind that the drying strength of the drying furnace 40 becomes a lower drying strength than the predetermined drying strength, After the coating step Pr1 is interrupted, during a period from restart of the coating step Pr1 to a predetermined time point, the second drying step Pr22 is performed. After the predetermined time point, the first drying step is performed.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 describes a method for manufacturing an electrode. The above-mentioned electrode manufacturing method uses an electrode manufacturing apparatus including a feed roll, a coater, a drying oven, and a take-up roll. A strip of metal foil is wound around the feed roll. The feed roll is a raw roll around which the metal foil is wound. The coater is a coating unit that applies a coating liquid containing an active material to the metal foil fed from the feed roll. The drying oven dries the coating liquid applied to the metal foil with hot air. The take-up roll takes up the metal foil that has passed through the drying oven.

[0003] The method for manufacturing an electrode includes a coating step and a drying step. The coating step is a step of applying a coating liquid to a metal foil using a coater. The drying step is a step of continuously transporting the metal foil coated with the coating liquid after the coating step to a drying oven and drying the coating liquid applied to the metal foil in the drying oven. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 11-102696 Summary of the Invention [Problem to be solved by the invention]

[0005] When the production of electrodes is continued, the coating process may be interrupted at some point due to the need to replace the raw roll or to replenish the coating liquid in the coater. When the coating process is interrupted, there may be no metal foil coated with the coating liquid inside the drying furnace. In this case, it is desirable to stop the operation of the drying furnace, but it may take time to restart the drying furnace. For this reason, it is preferable to continue operating the drying furnace even if there is no metal foil coated with the coating liquid inside the drying furnace when the coating process is interrupted.

[0006] However, when the coating process is interrupted while the drying furnace is continuously operating and no metal foil coated with the coating liquid is present inside the drying furnace, the temperature of the drying furnace becomes higher than when a metal foil coated with the coating liquid is present inside the drying furnace.As a result, when the coating process is resumed, there is a risk that the coating liquid applied to the metal foil transported to the drying furnace immediately after the resumption of the coating process will be overdried. [Means for solving the problem]

[0007] The method for manufacturing an electrode that solves the above-mentioned problems uses an electrode manufacturing apparatus including a raw web around which a strip-shaped substrate is wound, a coating unit that coats a coating liquid containing an active material on the substrate fed from the raw web, a drying oven that dries the coating liquid coated on the substrate with hot air, and a take-up roll that winds up the substrate that has passed through the drying oven, and includes a coating step of coating the substrate with the coating liquid by the coating unit, and a drying step of drying the coating liquid in the drying oven while continuously transporting the substrate coated with the coating liquid after the coating step to the drying oven, wherein the drying step is carried out by The method includes a first drying process that is carried out by operating the drying oven at a volume and temperature of the hot air that results in a predetermined drying strength, and a second drying process that is carried out by operating the drying oven at a volume and temperature of the hot air that results in a drying strength that is lower than the predetermined drying strength, and when the coating process is interrupted during the first drying process, the drying oven is operated so that the predetermined drying strength is maintained, and the second drying process is carried out during the period from when the coating process is resumed after the coating process is interrupted until a predetermined time point, and the first drying process is carried out after the predetermined time point.

[0008] According to the above-described electrode manufacturing method, during the period from the resumption of the coating process to a predetermined time, the second drying process is performed, and then the first drying process is performed again. That is, the drying strength of the drying oven can be temporarily reduced when drying the coating liquid that is transported to the drying oven for the first time after the coating process is resumed. Therefore, even if the temperature of the drying oven increases while the coating process is suspended, the coating liquid that is transported to the drying oven for the first time after the coating process is resumed can be prevented from being over-dried.

[0009] In the above-described method for manufacturing an electrode, the predetermined time point may be a time point after the coating liquid, which has been transported to the drying furnace for the first time since the coating step was restarted, has passed through the drying furnace. According to the above-described electrode manufacturing method, the second drying step is always performed while the coating liquid transported to the drying oven for the first time after the coating step is resumed remains in the drying oven. Therefore, the drying strength of the drying oven can be maintained at a reduced level until the coating liquid transported to the drying oven for the first time after the coating step is resumed passes through the drying oven. Therefore, the coating liquid transported to the drying oven for the first time after the coating step is resumed can be more reliably prevented from being overdried.

[0010] In the above-described method for manufacturing an electrode, in the second drying step, the drying intensity may be reduced by reducing the volume of the hot air in the drying furnace. The drying state of the coating liquid is determined by the drying strength of the drying oven, i.e., the volume and temperature of the hot air in the drying oven. The time required to adjust the volume of the hot air is shorter than the time required to adjust the temperature of the hot air. Therefore, in the above-mentioned electrode manufacturing method, a method of reducing the volume of the hot air in the drying oven is selected to reduce the drying strength of the drying oven in the second drying step, thereby instantly affecting the drying state of the coating liquid. Therefore, excessive drying of the coating liquid can be further suppressed.

[0011] In the above-described electrode manufacturing method, the coating process is interrupted when the raw roll is replaced, and the raw roll with the smaller amount of substrate is designated as the old raw roll, and the raw roll with the larger amount of substrate is designated as the new raw roll. The replacement of the raw roll includes bonding together the end end of the substrate on the old raw roll and the start end of the substrate on the new raw roll while continuing to wind up the substrate on the winding roll, and the coating process is interrupted until the bonded portion of the end end and the start end passes the coating section, and the coating process is resumed after the bonded portion of the end end and the start end passes the drying oven.

[0012] According to the above-described electrode manufacturing method, the substrate continues to be wound around the winding roll while the terminal end of the substrate on the old web and the starting end of the substrate on the new web are stuck together. This allows the substrate to be maintained in a state where it has always passed through the drying oven. In other words, it is possible to avoid the need to pass the starting end of the substrate on the new web through the drying oven again after the terminal end of the substrate on the old web has been wound around the winding roll. This allows the substrate to be efficiently handled in the drying oven when replacing the web, thereby enabling the electrode to be manufactured in an optimal manner.

[0013] Furthermore, the portion where the end of the substrate on the old web and the beginning of the substrate on the new web are bonded together is discarded without being used for the electrode. The coating process is interrupted until the portion where the end of the substrate on the old web and the beginning of the substrate on the new web are bonded together passes through the coating section. The coating process is then resumed after the portion where the end of the substrate on the old web and the beginning of the substrate on the new web are bonded together passes through a drying oven. This prevents the coating liquid from being wasted on the discarded portion of the current collector, thereby reducing the cost of the coating liquid. [Effects of the Invention]

[0014] According to this invention, it is possible to prevent the coating liquid that is transported to the drying furnace for the first time after the coating process is restarted from being overdried. [Brief explanation of the drawings]

[0015] [Figure 1] 1A to 1C are schematic diagrams illustrating a method for manufacturing an electrode. [Figure 2] FIG. 10 is a schematic diagram showing replacement of the raw material. [Figure 3] FIG. 10 is a schematic view showing when the coating process is resumed. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, a specific embodiment of the method for producing an electrode will be described with reference to FIGS. <Electrode manufacturing equipment> As shown in FIG. 1 , an electrode manufacturing method uses an electrode manufacturing apparatus 10. The electrode manufacturing apparatus 10 includes a raw web 20, a coating unit 30, four drying furnaces 40, and a winding roll 50. A strip-shaped current collector 100 is wound around the raw web 20. The current collector 100 is an example of a substrate. The current collector 100 has a first surface 101 and a second surface 102. The current collector 100 is transported from the raw web 20 toward the winding roll 50. The direction in which the current collector 100 is transported is referred to as a transport direction A.

[0017] The coating unit 30 faces the first surface 101 of the current collector 100. The coating unit 30 is disposed downstream of the web 20 in the conveyance direction A. The coating unit 30 is a device that applies a coating liquid 31 to the current collector 100 fed from the web 20. The coating liquid 31 contains a positive electrode active material or a negative electrode active material. Thus, the coating liquid 31 contains an active material. The coating unit 30 adjusts the amount of the coating liquid 31 discharged onto the current collector 100. The coating unit 30 is filled with the coating liquid 31, or the coating liquid 31 is supplied from a supply device (not shown). In this embodiment, the coating unit 30 intermittently applies the coating liquid 31 to the first surface 101 of the current collector 100 being conveyed in the conveyance direction A.

[0018] When the electrode manufactured in this embodiment is, for example, a positive electrode for use in a lithium-ion battery, the coating liquid 31 contains a positive electrode active material that can absorb and release charge carriers such as lithium ions. The positive electrode active material may be any material that can be used as a positive electrode active material for lithium-ion secondary batteries, such as a lithium composite metal oxide having a layered rock salt structure, a metal oxide having a spinel structure, or a polyanionic compound. Two or more positive electrode active materials may also be used in combination.

[0019] When the electrode manufactured in this embodiment is, for example, a negative electrode used in a lithium-ion battery, the coating liquid 31 can be any element, alloy, or compound capable of absorbing and releasing charge carriers such as lithium ions. Examples of the negative electrode active material include Li, carbon, metal compounds, elements or compounds thereof that can be alloyed with lithium, etc. Examples of carbon include natural graphite, artificial graphite, hard carbon (non-graphitizable carbon), and soft carbon (easily graphitizable carbon). Examples of artificial graphite include highly oriented graphite and mesocarbon microbeads. Examples of elements that can be alloyed with lithium include silicon and tin.

[0020] The current collector 100 employed in this embodiment is a chemically inactive electrical conductor that allows current to continue to flow through an active material layer formed by the coating liquid 31 applied to the current collector 100 during, for example, discharging or charging a lithium-ion secondary battery. The material of the current collector 100 is, for example, a metal material, a conductive resin material, or a conductive inorganic material. Examples of conductive resin materials include resins obtained by adding a conductive filler to a conductive polymer material or a non-conductive polymer material as needed. The current collector 100 may have multiple layers. In this case, each layer of the current collector 100 may contain the above-mentioned metal material and / or conductive resin material. The electrode manufactured in this embodiment may also be an electrode used in batteries other than lithium-ion batteries. In this case, the active material contained in the coating liquid 31 is not limited to the above and may be changed as appropriate.

[0021] The four drying ovens 40 are disposed between the raw web 20 and the winding roll 50 in the conveying direction A. The four drying ovens 40 are disposed downstream of the coating unit 30 in the conveying direction A. The four drying ovens 40 are aligned in the conveying direction A. The current collector 100 coated with the coating liquid 31 by the coating unit 30 is continuously transported to the four drying ovens 40.

[0022] Each of the four drying ovens 40 has a box-shaped oven body 41 and a hot air generator 42. The oven body 41 of each of the four drying ovens 40 is open in the conveying direction A so that the current collector 100 can pass through. The hot air generator 42 includes a heat generator 42a and a fan 42b. The heat generator 42a includes, for example, a boiler as a heat source and a heat exchanger. The heat generator 42a supplies heat from water vapor generated when water is evaporated in the boiler to the air surrounding the fan 42b via the heat exchanger. Note that the heat generator 42a may be configured as appropriate as long as it can supply heat to the air surrounding the fan 42b.

[0023] The fan 42b generates airflow that flows in the direction B opposite to the conveyance direction A within the furnace body 41. The fan 42b sends the surrounding air that has absorbed the heat generated by the heat generating unit 42a into the interior of the furnace body 41. That is, the fan 42b sends hot air into the interior of the furnace body 41. When the current collector 100 coated with the coating liquid 31 passes through the interior of the furnace body 41, the coating liquid 31 is dried by the hot air sent into the furnace body 41. The four drying furnaces 40 dry the coating liquid 31 applied to the current collector 100 with the hot air. The hot air sent into the furnace body 41 is drawn back into the hot air generating unit 42 by the fan 42b. That is, the hot air generated by the hot air generating unit 42 circulates inside the furnace body 41.

[0024] The coating liquid 31 is dried in the four drying ovens 40, thereby forming a coating film 32 on the first surface 101 of the current collector 100. The coating film 32 is formed on the current collector 100 that has passed through the four drying ovens 40. In other words, an electrode is formed by passing the current collector 100, to which the coating liquid 31 has been applied, through the four drying ovens 40. Then, the take-up roll 50 takes up the current collector 100 that has passed through the four drying ovens 40. An electrode is taken up around the take-up roll 50.

[0025] The hot air volume and temperature may be set to be the same or different for each of the four drying ovens 40. In this embodiment, the hot air volume and temperature are set to be the same for the three drying ovens 40 except for the drying oven 40 located most downstream in the conveyance direction A. The hot air volume and temperature for the drying oven 40 located most downstream in the conveyance direction A are set to be lower than the hot air volume and temperature for the other three drying ovens 40. By adjusting the hot air volume and temperature for the drying oven 40 located most downstream, it is possible to dry the coating liquid 31 to a degree that does not result in excessive drying.

[0026] <Electrode manufacturing method> 1, the method for manufacturing an electrode includes a coating step Pr1 and a drying step Pr2. The coating step Pr1 is a step in which a coating liquid 31 is applied to a current collector 100 by an application unit 30. The drying step Pr2 is a step carried out after the coating step Pr1. The drying step Pr2 is a step in which the coating liquid 31 is dried in a drying oven 40 while the current collector 100, onto which the coating liquid 31 has been applied after the coating step Pr1, is continuously transported to the drying oven 40.

[0027] The drying process Pr2 includes a first drying process Pr21 and a second drying process Pr22. The first drying process Pr21 is performed by operating each of the drying ovens 40 at a hot air volume and temperature that results in a predetermined drying intensity in each drying oven 40. The drying intensity in each drying oven 40 is an index that indicates how easily the coating liquid 31 present inside the drying oven 40 dries. The drying intensity in each drying oven 40 is determined by the hot air volume and temperature in the drying oven 40. The predetermined drying intensity in this embodiment is a drying intensity set in each of all drying ovens 40 so that the coating liquid 31 is suitably dried while the coating process Pr1 is being continuously performed. As described above, in this embodiment, the predetermined drying intensity in each of the three drying ovens 40 except for the drying oven 40 located most downstream is set to be higher than the predetermined drying intensity in the drying oven 40 located most downstream. The second drying step Pr22 is performed by operating each of the drying ovens 40 at a hot air volume and temperature that results in a drying strength lower than a predetermined drying strength in each of the drying ovens 40. The electrode manufacturing method may also include, for example, a cooling step of cooling the current collector 100 that has passed through the drying oven 40. The electrode manufacturing method may include the coating step Pr1 and the drying step Pr2.

[0028] <About interruption of coating process> When the production of the electrode continues, the coating step Pr1 may be interrupted until preparations are complete to resume the production of the electrode, for example, to replace the raw web 20 or to replenish the coating unit 30 with the coating liquid 31. Immediately after the coating step Pr1 is interrupted, undried coating liquid 31 remains on the current collector 100. For this reason, by continuing to operate all of the drying furnaces 40, the drying step Pr2 can be continued, and the winding of the current collector 100 by the winding roll 50 can also be continued.

[0029] Note that interrupting the coating step Pr1 does not simply mean not discharging the coating liquid 31 from the coating unit 30. In this embodiment, there is a stop period during which the coating liquid 31 is not temporarily applied because the coating liquid 31 is intermittently applied to the current collector 100. Interrupting the coating step Pr1 is a period until preparations are made to resume the production of the electrode, and means not discharging the coating liquid 31 from the coating unit 30 for a period longer than the stop period.

[0030] <Replacing the raw material and coating process> In this embodiment, the coating process Pr1 is interrupted when the raw web 20 is replaced. The operation when replacing the raw web 20 will be described below with reference to Figures 2 and 3. When replacing the raw web 20, the raw web 20 with the smaller amount of current collector 100 is designated as the old raw web 201, and the raw web 20 with the larger amount of current collector 100 is designated as the new raw web 202.

[0031] As shown in FIG. 2 , replacement of the workpiece 20 involves bonding together the end 100b of the current collector 100 on the old workpiece 201 and the start 100a of the current collector 100 on the new workpiece 202 while continuing to wind the current collector 100 on the winding roll 50. The start 100a and the end 100b are the ends of the long sides of the current collector 100. The start 100a is the end of the current collector 100 that is fed out first when the current collector 100 is fed out of the workpiece 20. The end 100b is the end of the current collector 100 that is fed out last as the current collector 100 is fed out of the workpiece 20. The end 100b of the current collector 100 on the old workpiece 201 and the start 100a of the current collector 100 on the new workpiece 202 are attached together, for example, with double-sided tape.

[0032] The coating step Pr1 is interrupted before the portion where the end 100b of the current collector 100 in the old web 201 and the beginning 100a of the current collector 100 in the new web 202 are bonded together passes through the coating unit 30.

[0033] All drying ovens 40 perform the first drying step Pr21 while electrodes are being manufactured continuously in the drying step Pr2 before the coating step Pr1 is interrupted. Even if the coating step Pr1 is interrupted, all drying ovens 40 continue to perform the first drying step Pr21. In other words, the first drying step Pr21 is a step of operating each drying oven 40 so as to maintain a predetermined drying strength when the coating step Pr1 is interrupted during the first drying step Pr21. Note that while the coating step Pr1 is interrupted, the winding of the current collector 100 by the winding roll 50 continues, so that the drying of the coating liquid 31 by the drying ovens 40 and the handling of the new raw roll 202 of the current collector 100 in all drying ovens 40 are performed simultaneously.

[0034] 3, as the winding of the current collector 100 by the winding roll 50 continues, the bonded portion of the end 100b of the current collector 100 wound around the old web 201 and the start 100a of the current collector 100 on the new web 202 passes through all of the drying ovens 40. It takes, for example, about one minute for the bonded portion of the end 100b of the current collector 100 wound around the old web 201 and the start 100a of the current collector 100 on the new web 202 to pass through all of the drying ovens 40. In this embodiment, the coating step Pr1 is resumed after the bonded portion of the end 100b of the current collector 100 wound around the old web 201 and the start 100a of the current collector 100 on the new web 202 has passed through all of the drying ovens 40. The portion where the end 100b of the current collector 100 in the old web 201 and the start 100a of the current collector 100 in the new web 202 are joined is cut off and discarded. The portion of the new web 202 where the start 100a of the current collector 100 was cut off is then attached to a new winding roll 50.

[0035] <After the coating process is resumed> When the coating step Pr1 is interrupted while all of the drying ovens 40 are continuously operating, the current collectors 100 continue to be wound around the take-up roll 50, and eventually, no current collectors 100 coated with the coating liquid 31 remain inside the drying ovens 40. That is, only current collectors 100 not coated with the coating liquid 31 remain inside the drying ovens 40. In this state, the coating liquid 31 does not absorb the heat from the drying ovens 40, and the temperatures of all of the drying ovens 40 may become higher than the temperatures of the drying ovens 40 when current collectors 100 coated with the coating liquid 31 are present inside the drying ovens 40. For this reason, there is a risk that the coating liquid 31 that is transported to the drying ovens 40 for the first time after the coating step Pr1 is resumed may be overdried.

[0036] In this regard, the present embodiment employs a method that can prevent over-drying of the coating liquid 31 that is transported to the drying furnace 40 for the first time after the coating process Pr1 is resumed. In the present embodiment, during the period from the suspension of the coating process Pr1 to the restart of the coating process Pr1 until a predetermined point in time, all of the drying furnaces 40 perform the second drying process Pr22.

[0037] The period from the resumption of the coating process Pr1 to a predetermined point in time is set by experimentally confirming in advance that the coating liquid 31, which is transported to the drying ovens 40 for the first time after the resumption of the coating process Pr1, is sufficiently dried when it has passed through all the drying ovens 40, and that the coating film 32 does not peel off from the current collector 100.

[0038] The predetermined time point is changed as appropriate depending on the length of the drying path of the coating liquid 31, etc. The predetermined time point may be the time point when the coating liquid 31 transported to the drying ovens 40 for the first time after the restart of the Coating step Pr1 has passed through all of the drying ovens 40, or a later time point. The predetermined time point may be any time point when the coating liquid 31 transported to the drying ovens 40 for the first time after the restart of the Coating step Pr1 is located inside the drying ovens 40. That is, the predetermined time point may be set at least as the time point after the coating liquid 31 transported to the drying ovens 40 for the first time after the restart of the Coating step Pr1 has entered the drying ovens 40. The predetermined time point may also be determined based on the time it takes for the temperature of the drying oven 40 located furthest downstream in the transport direction A to decrease to the same temperature as before the interruption of the Coating step Pr1. In other words, the predetermined time point is arbitrary as long as the coating liquid 31 transported to the drying ovens 40 for the first time after the restart of the Coating step Pr1 can be sufficiently dried to prevent it from peeling off from the current collector 100.

[0039] In this embodiment, the time point after the coating liquid 31, which is transported to the drying ovens 40 for the first time after the coating step Pr1 is restarted, has passed through all the drying ovens 40, is set as the predetermined time point. In the second drying step Pr22, the hot air volume in all drying ovens 40 is reduced, thereby reducing the drying intensity in each drying oven 40. In other words, when the coating step Pr1 is resumed, the output of the fans 42b in each drying oven 40 is reduced below the output of the fans 42b in each drying oven 40 when the first drying step Pr21 is being performed. In this embodiment, the output of each fan 42b in each drying oven 40 is reduced in response to a signal output from the coating unit 30 when the coating step Pr1 is resumed, thereby reducing the hot air volume. Therefore, the force of the hot air blown onto the coating liquid 31 that is transported to the drying oven 40 for the first time after the coating step Pr1 is resumed is weakened. This reduces the amount of heat absorbed by the coating liquid 31 from the hot air. Furthermore, the moisture contained in the coating liquid 31 is less likely to volatilize, making the coating liquid 31 less likely to dry. This prevents the coating liquid 31 from being overdried when it is transported to the drying oven 40 for the first time immediately after the coating step Pr1 is resumed.

[0040] During the period from the resumption of the coating process Pr1 until a predetermined point in time, all drying ovens 40 perform the second drying process Pr22 and then perform the first drying process Pr21 again. That is, all drying ovens 40 perform the first drying process Pr21 after the predetermined point in time. The predetermined point in time is synonymous with the point in time when the hot air flow rate in all drying ovens 40 is returned to the same level as immediately before the resumption of the coating process Pr1. That is, each drying oven 40 temporarily reduces the drying intensity by performing the second drying process Pr22 to prevent over-drying of the coating liquid 31 that is transported to the drying oven 40 for the first time after the resumption of the coating process Pr1.

[0041] <Relationship between fan output and coating film peeling before and after restarting the coating process> As shown in Table 1, the comparative example is an electrode formed when the hot air flow rate in all drying furnaces 40 was not changed before and after the resumption of coating process Pr1 in the manufacture of the electrode. The example is an electrode formed according to this embodiment in the manufacture of the electrode. Note that the output of fan 42b before the resumption of coating process Pr1 is the same in the manufacture of the comparative example and the example. The numerical values ​​indicating the output of fan 42b after the resumption of coating process Pr1 listed in Table 1 are numerical values ​​when the output of fan 42b before the resumption of coating process Pr1 is set to "100".

[0042] The inventors of the present application conducted a bending test using the cylindrical mandrel method specified in JIS K 5600-5-1 to check for peeling of the coating film 32 from the current collector 100 in each of the comparative example and example. The mandrel used had a diameter of 20 mm. The results are shown in Table 1. Peeling of the coating film 32 in the comparative example was evaluated as "× (peeling occurred)," while peeling of the coating film 32 in the example was evaluated as "◯ (no peeling)." In short, the above test results indicate that when the coating step Pr1 is resumed, reducing the volume of hot air in all drying ovens 40 prevents over-drying of the coating liquid 31, thereby maintaining the adhesive strength of the coating film 32 to the current collector 100.

[0043] [Table 1]

[0044] [Actions and Effects of This Embodiment] The operation and effects of this embodiment will be described. (1) During the period from the resumption of the coating process Pr1 to a predetermined point in time, the second drying process Pr22 is performed, and then the first drying process Pr21 is performed again. In other words, the drying strength of the drying furnace 40 can be temporarily reduced when drying the coating liquid 31 that is transported to the drying furnace 40 for the first time after the coating process Pr1 is resumed. Therefore, even if the temperature of the drying furnace 40 increases while the coating process Pr1 is suspended, the coating liquid 31 that is transported to the drying furnace 40 for the first time after the coating process Pr1 is resumed can be prevented from being over-dried.

[0045] (2) The predetermined time point is the time point after the coating liquid 31, which is transported to the drying oven 40 for the first time after the coating process Pr1 is restarted, has passed through all of the drying ovens 40. Therefore, the second drying process Pr22 is always performed while the coating liquid 31, which is transported to the drying oven 40 for the first time after the coating process Pr1 is restarted, is present in the drying oven 40. Therefore, by reducing the volume of hot air from the drying oven 40, the drying strength of the drying oven 40 can be maintained at a reduced level until the coating liquid 31, which is transported to the drying oven 40 for the first time after the coating process Pr1 is restarted, passes through the drying oven 40. Therefore, it is possible to more reliably prevent the coating liquid 31, which is transported to the drying oven 40 for the first time after the coating process Pr1 is restarted, from being overdried.

[0046] (3) In the second drying step Pr22, the drying intensity of the drying furnace 40 is reduced by reducing the volume of hot air in the drying furnace 40. The time required to adjust the volume of hot air is shorter than the time required to adjust the temperature of the hot air.

[0047] For this reason, in this embodiment, in order to reduce the drying intensity of the drying furnace 40 in the second drying step Pr22, a method of reducing the volume of hot air in the drying furnace 40 is selected, which can instantaneously affect the dry state of the coating liquid 31. As a result, excessive drying of the coating liquid 31 can be further suppressed.

[0048] (4) The winding of the current collector 100 by the take-up roll 50 continues in a state in which the end 100b of the current collector 100 in the old web 201 and the start 100a of the current collector 100 in the new web 202 are stuck together. This allows the current collector 100 to be maintained in a state in which it has always passed through all of the drying ovens 40. In other words, it is possible to avoid the need to pass the start 100a of the current collector 100 in the new web 202 through all of the drying ovens 40 again after the end 100b of the current collector 100 in the old web 201 has been taken up by the take-up roll 50. This allows the current collector 100 to be efficiently routed to all of the drying ovens 40 when the web 20 is replaced, thereby enabling the electrode to be manufactured in an efficient manner.

[0049] (5) The portion where the end 100b of the current collector 100 in the old web 201 and the start 100a of the current collector 100 in the new web 202 are bonded together is not used for an electrode and is discarded. The coating step Pr1 is interrupted before the portion where the end 100b of the current collector 100 in the old web 201 and the start 100a of the current collector 100 in the new web 202 are bonded together passes through the coating unit 30. The coating step Pr1 is then resumed after the portion where the end 100b of the current collector 100 in the old web 201 and the start 100a of the current collector 100 in the new web 202 are bonded together passes through the drying furnace 40. This prevents the coating liquid 31 from being wasted on the discarded portion of the current collector 100, thereby reducing the cost of the coating liquid 31.

[0050] [Example of change] This embodiment can be modified as follows: This embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0051] When replacing the work roll 20, it is not necessary to bond the end 100b of the current collector 100 on the old work roll 201 to the start 100a of the current collector 100 on the new work roll 202. The start 100a of the current collector 100 on the new work roll 202 may be passed through all of the drying ovens 40 after all of the current collectors 100 wound on the old work roll 201 have been taken up onto the take-up roll 50. In this case, the coating step Pr1 only needs to be interrupted before the end 100b of the current collector 100 on the old work roll 201 passes through the coating unit 30.

[0052] The coating step Pr1 may be interrupted when the coating unit 30 is replenished with the coating liquid 31 . In the second drying step Pr22, the drying intensity of the drying oven 40 may be reduced by reducing both the volume and temperature of the hot air in the drying oven 40. In such a modification, the heat generating unit 42a of the drying oven 40 may reduce the temperature of the hot air, for example, by reducing the output of the boiler that is the heat source of the heat generating unit 42a, in response to a signal output from the application unit 30 when the application step Pr1 is resumed.

[0053] In the second drying step Pr22, the drying intensity of the drying furnace 40 may be reduced by lowering only the temperature of the hot air in the drying furnace 40. Although the first drying step Pr21 and the second drying step Pr22 are performed as the drying step Pr2 in all drying ovens 40, this is not limited to this. It is sufficient that the first drying step Pr21 and the second drying step Pr22 are performed as the drying step Pr2 in at least one drying oven 40 among the plurality of drying ovens 40.

[0054] The number of drying ovens 40 may be five or more, or may be three or less. The electrode manufacturing apparatus 10 may include a support roll that assists the transport of the current collector 100 in the transport direction A, in addition to the raw web 20 and the winding roll 50 .

[0055] As a test to check for peeling of the coating film 32 from the current collector 100, a test may be added in which the current collector 100 on which the coating film 32 has been formed is wound around the winding roll 50 or the roll with the smallest diameter among the above-mentioned support rolls at the largest possible wrap angle.

[0056] The coating unit 30 may continuously apply the coating liquid 31 to the first surface 101 of the current collector 100 being transported in the transport direction A. Although the current collector 100 is wound around the raw web 20, for example, the current collector 100 may be wound with a coating film already formed on its second surface 102. In this case, the current collector 100 with a coating film already formed on its second surface 102 is an example of a substrate. For example, a bipolar electrode can be produced by forming a coating film containing a positive electrode active material on the first surface 101 of the current collector 100 and a coating film containing a negative electrode active material on the second surface 102 of the current collector 100 according to this modified example. [Explanation of symbols]

[0057] 10...electrode manufacturing apparatus, 20...raw roll, 30...coating section, 31...coating liquid, 40...drying furnace, 50...winding roll, 100...current collector as substrate, 100a...starting end of current collector, 100b...end of current collector, 201...old raw roll, 202...new raw roll, Pr1...coating process, Pr2...drying process, Pr21...first drying process, Pr22...second drying process.

Claims

1. an electrode manufacturing apparatus including: a raw roll around which a strip-shaped substrate is wound; a coating unit that coats a coating liquid containing an active material on the substrate fed from the raw roll; a drying oven that dries the coating liquid coated on the substrate with hot air; and a winding roll that winds up the substrate that has passed through the drying oven; a coating step of applying the coating liquid to the substrate by the coating unit; a drying step of drying the coating liquid in the drying furnace while continuously transporting the substrate coated with the coating liquid into the drying furnace after the coating step, The drying step includes: a first drying step in which the drying oven is operated at a volume and temperature of the hot air such that the drying intensity of the drying oven is a predetermined drying intensity; a second drying step that is carried out by operating the drying oven at an air volume and a temperature of the hot air that make the drying intensity of the drying oven lower than the predetermined drying intensity, When the coating step is interrupted during the first drying step, the drying oven is operated so as to maintain the predetermined drying intensity; performing the second drying step during a period from when the coating step is interrupted and then resumed until a predetermined time point; A method for manufacturing an electrode, characterized in that the first drying step is carried out after the predetermined time point.

2. The method for manufacturing an electrode according to claim 1 , wherein the predetermined time point is a time point after the coating liquid, which is transported to the drying furnace for the first time after the coating step is restarted, has passed through the drying furnace.

3. 3. The method for manufacturing an electrode according to claim 1, wherein in the second drying step, the drying intensity is reduced by reducing the volume of the hot air in the drying furnace.

4. The coating process is interrupted when the raw material is replaced, The raw roll having the smaller amount of the substrate is called an old raw roll, and the raw roll having the larger amount of the substrate is called a new raw roll. replacing the web includes bonding together the end of the substrate on the old web and the beginning of the substrate on the new web while continuing to wind the substrate on the winding roll; 3. The method for manufacturing an electrode according to claim 1, wherein the coating step is interrupted before the portion where the end end and the start end are bonded together passes through the coating section, and the coating step is resumed after the portion where the end end and the start end are bonded together passes through the drying oven.

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