Electrode sheet drying device, electrode sheet manufacturing system including the same, and electrode sheet drying method

Abstract

The present invention relates to an electrode sheet drying device, a manufacturing system including the same, and a method for drying an electrode sheet, which includes an air floating roller disposed downstream of a drying oven, and the air floating roller is configured to inject hot air through a plurality of air injection holes formed on an outer circumferential surface thereof. This allows the electrode sheet discharged from the drying oven in a partially undried state to be additionally dried, thereby preventing contamination of a transfer roller and / or equipment in a subsequent process.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2021-0188503, dated December 27, 2021.

[0002] The present invention relates to an electrode sheet drying device, an electrode sheet manufacturing system including the same, and an electrode sheet drying method. Specifically, the present invention relates to an electrode sheet drying device that, when an electrode sheet is not completely dried in a drying oven to prevent overdrying, has an air floating roller disposed downstream of the drying oven to compensate for insufficient drying, an electrode sheet manufacturing system including the same, and an electrode sheet drying method. [Background technology]

[0003] Lithium secondary batteries include electrodes containing electrically active materials, and these electrodes are manufactured by coating a sheet-shaped current collector with an electrode slurry to form an electrode mixture layer and drying it. The electrode manufacturing process typically involves an electrode slurry coating device and an electrode sheet drying device, which include a drying oven equipped with a hot air supply unit that supplies convection heat and / or a heater that supplies radiant heat to dry the mixture layer of the electrode substrate, and a transport roller that is positioned outside the exit of the drying oven and that transports the electrode sheet with the dried mixture layer.

[0004] If the electrode sheet is completely dried in a drying oven after being coated with the electrode slurry, the electrode sheet may be dried more than necessary, resulting in overdrying, which can cause heat wrinkles, cracks, etc. in the electrode sheet and reduce the quality of the electrode. Therefore, if necessary, the electrode sheet is often not completely dried in the drying oven, and is intentionally discharged from the drying oven while some of it is still wet.

[0005] However, although such an electrode sheet that is not completely dried can improve heat wrinkles, cracks, and the like, it may contaminate the transport rollers and may create unfavorable conditions for subsequent processes such as a rolling process or a punching and notching process.

[0006] Therefore, in order to prevent the electrode sheet from being over-dried, it is necessary to solve the above-mentioned problems when an electrode sheet that is not completely dried is discharged from a drying oven and wound up. Summary of the Invention [Problem to be solved by the invention]

[0007] When an electrode sheet is not completely dried in a drying oven but is intentionally left partially undried in order to prevent the electrode sheet from being over-dried, the partially undried electrode sheet may contaminate devices such as transport rollers and / or rolling rollers used in subsequent processes, thereby creating unfavorable conditions in subsequent rolling processes, etc., and the present invention aims to improve this problem. [Means for solving the problem]

[0008] According to one embodiment of the present invention, there is provided an electrode sheet drying device including: a drying oven having an internal space for drying an electrode sheet formed by applying electrode slurry onto a current collector; and one or more air-floating rollers disposed downstream of the drying oven and configured to spray hot air onto the electrode sheet.

[0009] In one embodiment of the present invention, the air floating roller may have a hollow cylindrical shape with a hollow interior and may have a plurality of air injection holes on the outer circumferential surface.

[0010] In one embodiment of the present invention, the diameter of the air injection holes may be in the range of 0.5 mm to 15 mm.

[0011] In one embodiment of the present invention, the air floating roller can be positioned so that the contact angle with the electrode sheet is 90° or less.

[0012] In one embodiment of the present invention, at least one of the air floating rollers may be arranged to spray hot air against a first surface of the electrode sheet facing upward in the drying oven.

[0013] In one embodiment of the present invention, at least one of the air floating rollers may be arranged to spray hot air against the second surface of the electrode sheet facing downward in the drying oven.

[0014] In one embodiment of the present invention, the air floating roller may include both a first air floating roller arranged to spray hot air onto a first surface of the electrode sheet facing upward in the drying oven, and a second air floating roller arranged to spray hot air onto a second surface of the electrode sheet facing downward in the drying oven.

[0015] In one embodiment of the present invention, a suction roller may be disposed downstream of the air floating roller.

[0016] In one embodiment of the present invention, a partition wall may be installed around the air floating roller to isolate it from the outside space.

[0017] According to another embodiment of the present invention, there is provided a system for manufacturing an electrode sheet, including a winder that continuously unwinds a current collector, a coating unit that applies electrode slurry to one surface of the current collector supplied from the winder, the drying device disposed downstream of the coating unit, and a rewinder that winds up the electrode sheet discharged from the drying device.

[0018] According to another embodiment of the present invention, there is provided a method for drying an electrode sheet, which includes a main drying step of drying an electrode sheet formed by applying an electrode slurry onto a current collector in a drying oven, and an additional drying step of additionally drying the electrode sheet being transported after the main drying step, wherein the additional drying step is performed while the electrode sheet is traveling on an air-floating roller configured to spray hot air onto the electrode sheet.

[0019] In one embodiment of the present invention, the main drying step may be a process of partially drying the electrode sheet so that the solvent removal rate calculated by the following formula 1 is 50% to 90%.

[0020] [Formula 1] Solvent removal rate (%) = (weight of electrode sheet before main drying process - weight of electrode sheet after main drying process) x 100 / (weight of electrode sheet before main drying process - weight of electrode sheet after additional drying process)

[0021] In one embodiment of the present invention, the air floating roller may have a hollow cylindrical shape with an open interior and may have a plurality of air injection holes for injecting hot air onto the outer circumferential surface.

[0022] In one embodiment of the present invention, the pressure of the hot air injected from one air injection hole may be 0.01 MPa to 0.5 MPa.

[0023] In one embodiment of the present invention, the temperature of the hot air ejected from the one air ejection hole may be 50°C to 150°C. [Effects of the Invention]

[0024] In the electrode sheet drying device and drying method according to the present invention, an air-floating roller is disposed downstream of a drying oven where main drying is performed, and the air-floating roller sprays hot air onto the electrode sheet after main drying, thereby making it possible to compensate for insufficient drying in the drying oven.

[0025] In addition, the electrode manufacturing system according to the present invention does not completely dry the electrode sheet in a drying oven, so that it is possible to manufacture an electrode sheet that is free from cracks and wrinkles. Furthermore, the air floating roller compensates for insufficient drying, so that it has the effect of preventing contamination of subsequent devices such as a transfer roller and a rolling roller. [Brief explanation of the drawings]

[0026] [Figure 1] FIG. 1 is a schematic diagram of an electrode sheet drying device according to an embodiment of the present invention. [Figure 2] FIG. 1 is a schematic diagram of an air floating roller according to one embodiment of the present invention. [Figure 3] 1 illustrates various embodiments and comparative examples of the contact angle between an air floating roller and an electrode sheet. [Figure 4] 2 is a diagram illustrating various arrangements of an air floating roller, which is one of the components of part A in FIG. 1; [Figure 5] 1 is a view illustrating a portion of a drying device according to an embodiment of the present invention. [Figure 6] FIG. 10 is a schematic diagram of an electrode sheet drying device according to another embodiment of the present invention. [Figure 7] 1 is a schematic diagram of an electrode sheet manufacturing system according to an embodiment of the present invention. [Figure 8] 1 is a flowchart of a method for drying an electrode sheet according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention can be modified in various ways and can have various forms, and therefore, specific embodiments are shown in the drawings and described in detail herein, but it is not intended to limit the invention to the particular disclosed forms, and it should be understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and technical scope of the invention.

[0028] In this application, terms such as "comprise" and "have" are intended to specify the presence of a feature, numeral, step, operation, component, part, or combination thereof described in the specification, and are understood not to preclude the presence or addition of one or more other features, numerals, steps, operations, components, parts, or combinations thereof. Furthermore, when a layer, film, region, plate, or other part is described as being "on" another part, this includes not only the case where it is "directly on" the other part, but also the case where there is another part between them. Conversely, when a layer, film, region, plate, or other part is described as being "under" another part, this includes not only the case where it is "directly under" the other part, but also the case where there is another part between them. Furthermore, in this application, "over" can include not only the case where it is "on top" but also the case where it is "under" the other part.

[0029] In this specification, the x-axis corresponds to the direction in which the electrode sheet is transported, the y-axis corresponds to the width direction of the electrode sheet and the length direction of the air floating roller, and the z-axis corresponds to the direction perpendicular to the plane of the electrode sheet.

[0030] The present invention will now be described in more detail.

[0031] <Electrode sheet drying device> The electrode sheet drying device (hereinafter referred to as the "drying device") according to the present invention includes a drying oven having an internal space for drying an electrode sheet in which electrode slurry is applied onto a current collector, and one or more air-floating rollers that are arranged downstream of the drying oven and configured to spray hot air onto the electrode sheet.

[0032] Although the temperature inside the drying oven can be controlled to prevent the electrode sheet from over-drying, there are limitations to this. Because the transport speed of the electrode sheet inside the drying oven is increasing to improve productivity, if the temperature inside the drying oven is set too high to accommodate the increased transport speed, over-drying, in which only the surface of the electrode slurry is over-dried, may occur.

[0033] It can be technically very difficult to uniformly dry the surface and the inside of the electrode slurry through temperature control of the drying oven. The series of processes, which requires real-time monitoring of the weight, temperature, etc. of the electrode sheet discharged from the drying oven, determining the dryness level of the electrode sheet based on the data, and controlling the hot air temperature, hot air velocity, and heater temperature inside the drying oven according to the determined dryness level, requires considerable effort.

[0034] Therefore, in the drying apparatus of the present invention, even if a portion of the electrode sheet may remain undried, the temperature inside the drying oven is set not too high to prevent the surface of the electrode slurry from being over-dried, and an air floating roller is disposed downstream of the drying oven to additionally dry the electrode sheet that is in a partially undried state, thereby preventing contamination of the transfer roller and / or equipment in subsequent processes.

[0035] Furthermore, the drying apparatus of the present invention does not require a significant effort for temperature control inside the drying oven, and only requires the addition of an air floating roller during the electrode sheet transport process, which is advantageous in that no major design changes are required for existing drying apparatuses.

[0036] First Embodiment FIG. 1 is a schematic diagram of an electrode sheet drying device according to one embodiment of the present invention, and FIG. 2 is a schematic diagram of an air floating roller according to one embodiment of the present invention.

[0037] Referring to these drawings, the electrode sheet drying apparatus according to the present invention (hereinafter referred to as the “drying apparatus”, 100 ) includes a drying oven 110 and an air floating roller 121 .

[0038] The electrode sheet 10 dried by the drying apparatus 100 of the present invention includes a sheet-shaped current collector and electrode slurry applied to one or both sides of the current collector. That is, the electrode sheet 10 of the present invention is manufactured by coating one or both sides of a sheet-shaped current collector with electrode slurry, and the electrode slurry of the electrode sheet 10 manufactured in this manner is dried by the electrode drying apparatus 100 of the present invention.

[0039] The drying oven 110 has a storage space S for drying therein. An inlet 111 through which the electrode sheet 10 to be dried is input may be provided on one side of the drying oven 110 based on the electrode sheet transfer direction (x-axis direction), and an outlet 112 through which the electrode sheet 10 to be dried is outputted after the drying process may be provided on the other side. The drying oven 110 may include a frame F that defines the outer shape of the drying oven.

[0040] Drying means 113 for drying the electrode slurry is installed inside the drying oven 110, and specific examples of such drying means 113 include a hot air injection nozzle that injects hot air toward the electrode sheet 10 and / or a heater that supplies radiant heat. Such a heater may be configured to irradiate infrared rays or a laser toward the electrode sheet.

[0041] One or more drying means 113 may be installed above the electrode sheet 10 in the direction perpendicular to the plane of the electrode sheet 10 (z-axis direction). Although not shown in FIG. 1, drying means 113 may also be installed below the electrode sheet 10, which may increase drying efficiency.

[0042] When the drying means 113 is a hot air injection nozzle, the drying device 100 may further include a heat exchanger (not shown), a blower fan (not shown), and a duct (not shown) to supply hot air to the hot air injection nozzle.

[0043] The heat exchanger is configured to heat the outside air to be supplied to the hot air injection nozzle, and the blower fan is configured to blow the outside air heated by the heat exchanger through a duct into the hot air injection nozzle installed inside the drying oven 110. The duct may be configured to be in communication with the inside of the storage space to supply the heated outside air into the drying oven. In addition, a damper operated by an actuator is installed inside the duct, and the amount of hot air supplied into the storage space through the damper may be adjusted.

[0044] The temperature inside the drying oven 110 by such drying means can be set to less than 170°C, preferably 80°C to 150°C, and more preferably 90°C to 130°C.

[0045] In addition, one or more transfer rollers 114 for transferring the electrode sheet 10 in a transfer direction (x-axis direction) may be included inside the drying oven 110. The transfer rollers 114 may be rotated by a driving unit (not shown) that applies a rotational force to the transfer rollers 114, thereby causing the electrode sheet to travel in the transfer direction.

[0046] The transport speed of the electrode sheet can be 10 m / min to 50 m / min, specifically 12 m / min to 40 m / min, or 15 m / min to 50 m / min, or 20 m / min to 40 m / min, or 15 m / min to 30 m / min, or 20 m / min to 30 m / min.

[0047] The air floating roller 121 is disposed downstream of the drying oven 110 and configured to spray hot air onto the electrode sheet 10. The drying device 100 of the present invention may include one or more air floating rollers 121.

[0048] The air floating roller 121 is configured to spray hot air onto the electrode sheet 10 discharged from the drying oven, and the thermal energy of the hot air sprayed from the air floating roller 121 is transferred to the electrode slurry that is not completely dried, thereby further drying the electrode sheet 10. As a result, the drying apparatus 100 according to the present invention can prevent the transfer roller or equipment for a subsequent process from being contaminated by the electrode slurry that is not completely dried.

[0049] 2, the air floating roller 121 according to the present invention has a hollow cylindrical shape with a plurality of air injection holes 121c formed along the outer circumferential surface 121a. The plurality of air injection holes 121c may be uniformly distributed over the entire outer circumferential surface of the air floating roller 121, thereby allowing hot air to be injected uniformly over the entire surface of the electrode sheet.

[0050] The diameter of one air injection hole can be 0.5 mm to 15 mm, preferably 1 mm to 10 mm, and more preferably 3 mm to 7 mm. When the diameter of the air injection hole is within the above numerical range, hot air of an appropriate pressure can be injected onto the electrode sheet, which is preferable.

[0051] The length of the air floating roller 121 in the longitudinal direction (y-axis direction) may correspond to the length of the electrode sheet 10 in the width direction (y-axis direction). One side of the air floating roller 121 in the longitudinal direction (y-axis direction) may be formed with an opening 121b for supplying hot air into the internal space of the air floating roller 121, and the other side of the air floating roller 121 in the longitudinal direction (y-axis direction) may have a sealed structure.

[0052] The drying apparatus 100 of the present invention may include a hot air supply unit (not shown) for supplying hot air to the air floating roller 121, and the hot air supply unit may be connected to the opening 121b and configured to supply hot air into the inside of the air floating roller 121. The hot air supply unit supplies hot air into the inside of the air floating roller, so that the hot air can be sprayed toward the electrode sheet 10 through the air spray holes 121c.

[0053] The hot air supply unit may include an air blower (not shown) that generates hot air, and the air blower may be composed of a motor that provides driving force and an impeller that rotates when driven by the motor. In addition to the air blower, the hot air supply unit may further include an air compressor and an air control unit that controls the flow rate and pressure of the air.

[0054] The air floating roller 121 configured as above can inject high-pressure hot air onto the electrode sheet 10 through a plurality of air injection holes formed on the outer circumferential surface.

[0055] In one specific example, the air-floating roller 121 may be positioned so that the contact angle with the electrode sheet 10 is 90° or less. Here, the contact angle between the air-floating roller 121 and the electrode sheet 10 may be defined as the interior angle between the electrode sheet 10 immediately before it runs on the air-floating roller 121 and the electrode sheet 10 immediately after it has run on the air-floating roller 121.

[0056] Figure 3 illustrates various embodiments and comparative examples of the contact angle between the air-floating roller and the electrode sheet. Figure 3(a) illustrates a case where the contact angle between the air-floating roller and the electrode sheet is 90°, Figure 3(b) illustrates a case where the contact angle between the air-floating roller and the electrode sheet is 30°, Figure 3(c) illustrates a case where the contact angle between the air-floating roller and the electrode sheet is 60°, and Figure 3(d) illustrates a case where the contact angle between the air-floating roller and the electrode sheet is 120°. As can be seen from these drawings, the smaller the contact angle, the larger the surface area of ​​the electrode sheet 10 in contact with the air-floating roller 121.

[0057] The larger the contact area of ​​the electrode sheet 10 with the air-floating roller 121, the more advantageous it is for the air-floating roller 121 to transfer thermal energy. Therefore, when arranging the air-floating roller 121, it is preferable to arrange the air-floating roller 121 so that the contact angle with the electrode sheet 10 is 90° or less.

[0058] The size of the contact angle between the air floating roller 121 and the electrode sheet 10 can be adjusted by adjusting the positions of the transport roller (or guide roller) located directly in front of the air floating roller 121 and the transport roller (or guide roller) located directly behind the air floating roller 121, based on the transport direction (x-axis direction) of the electrode sheet.

[0059] As shown in (a) of FIG. 3, if the transfer roller (or guide roller) located directly in front of the air floating roller 121 is positioned vertically (z-axis direction) above the air floating roller 121, and the transfer roller (or guide roller) located directly behind the air floating roller 121 is positioned horizontally (x-axis direction) to the right of the air floating roller 121, the contact angle can be 90°.

[0060] Furthermore, as shown in Figures 3(b) and 3(c), if the transfer roller (or guide roller) located directly in front of the air floating roller 121 is positioned upward in the vertical direction (z-axis direction) based on the air floating roller 121, and the transfer roller (or guide roller) located directly behind the air floating roller 121 is positioned upward and to the right of the air floating roller 121, the contact angle may be less than 90°.

[0061] Also, as shown in FIG. 3(d), if the transfer roller (or guide roller) located directly in front of the air floating roller 121 is positioned above and to the left of the air floating roller 121, and the transfer roller (or guide roller) located directly behind the air floating roller 121 is positioned to the right in the horizontal direction (x-axis direction) of the air floating roller 121, the contact angle can exceed 90°.

[0062] According to an embodiment of the present invention, at least one of the air floating rollers may be arranged to spray hot air onto a first surface of the electrode sheet facing upward in the drying oven.

[0063] According to another embodiment of the present invention, at least one of the air floating rollers may be arranged to spray hot air onto a second surface of the electrode sheet facing downward in the drying oven.

[0064] According to another embodiment of the present invention, the air floating roller may include both a first air floating roller arranged to spray hot air onto a first surface of the electrode sheet facing upward in the drying oven, and a second air floating roller arranged to spray hot air onto a second surface of the electrode sheet facing downward in the drying oven.

[0065] FIG. 4 is a diagram illustrating various arrangements of the air floating roller, which is one of the components of portion A shown in FIG. 1. Referring to FIGS. 1 and 4, a drying means 113 that supplies hot air and / or radiant heat to the electrode sheet may be installed on the ceiling of a frame F that forms the outer shape of the drying oven 110. Because the electrode slurry that constitutes the electrode sheet 10 is a fluid, the electrode sheet 10 is transferred into the drying oven 110 with the portion on which the electrode slurry is applied facing the drying means 113. If the side of the electrode sheet 10 facing the drying means 113 is defined as the first side, the first side facing upward in the drying oven 110 is dried. That is, the electrode sheet is loaded into and discharged from the drying oven 110 with the first side facing upward and the second side, which is the opposite side of the first side, facing downward.

[0066] The electrode sheet 10 that is intentionally discharged from the drying oven 110 in a partially undried state is further dried by the air floating rollers 121, and the side of the electrode sheet that faces the air floating rollers 121 can be selected depending on the arrangement order of the air floating rollers 121.

[0067] 4(a), when a transfer roller 122, an air-floating roller 121, and another transfer roller 122 are arranged in this order along the transfer direction of the electrode sheet 10, the first surface of the electrode sheet comes into contact with the air-floating roller 121. In this case, the air-floating roller 121 may spray ultra-high pressure hot air to prevent contamination by partially undried electrode slurry, so that the electrode sheet 10 passes through the air-floating roller 121 in a floating state above it.

[0068] 4(b), when the air-floating roller 121 and the transfer roller 122 are arranged in this order along the transfer direction of the electrode sheet 10, the second side of the electrode sheet 10 comes into contact with the air-floating roller 121. In this case, the second side of the electrode sheet 10 is the current collector and cannot contaminate the air-floating roller 121. Therefore, the air-floating roller 121 can spray high-pressure hot air onto the electrode sheet 10 to additionally dry the first side of the electrode sheet 10. Typically, the electrode slurry on the electrode sheet 10 is dried in the drying oven 110 from the surface to the vicinity of the current collector. However, when the air-floating roller is arranged as shown in FIG. 4(b), hot air is sprayed onto the second side of the electrode sheet 10, which has the effect of efficiently additionally drying the electrode slurry near the undried current collector due to the difference in drying speed.

[0069] When the second air floating roller 121b, the first air floating roller 121a, and the transport roller 122 are arranged in this order along the transport direction of the electrode sheet 10, as shown in Figure 4(c), the second surface of the electrode sheet 10 comes into contact with the second air floating roller 121b, and the first surface of the electrode sheet comes into contact with the air floating roller 121a.

[0070] Although Figures 4(a) and 4(b) show one air floating roller 121, this is merely a diagram for simply explaining the arrangement order of the air floating roller and the transfer roller, and two or more air floating rollers may be installed in the arrangement order of the air floating rollers.

[0071] In one embodiment, the drying apparatus 100 according to the present invention may have a tension control roller 123 and a drive roller 124 disposed downstream of the air floating roller 121 in order to control the transport tension of the electrode sheet 10.

[0072] The drive roller 124 is capable of rotating by itself, and the tension control roller 123 is a non-drive roller that is not capable of rotating by itself, and they may be designed to be opposed to each other in a pair.

[0073] The drive roller 124 may be located below the electrode sheet 10, and the tension control roller 123 may be located above the electrode sheet 10. When the electrode sheet 10 passes between the drive roller 124 and the tension control roller 123, tension may be applied to the electrode sheet 10 due to the difference in the movement speed between the drive roller and the tension control roller.

[0074] In the electrode drying apparatus of the present invention, an electrode sheet is discharged from the drying oven 110 in a state where it is not completely dried, and if tension is not applied to the electrode sheet, wrinkles may occur in the electrode sheet in the partially undried areas. The drying apparatus of the present invention has the effect of suppressing the possibility of such wrinkles occurring by including the tension control roller 123 and the drive roller 124.

[0075] FIG. 5 is a view illustrating a part of a drying device according to an embodiment of the present invention.

[0076] 5, the drying apparatus 100 according to the present invention may have a partition 130 installed around the air floating roller 121 to isolate it from the outside. The partition 130 can reduce the loss of thermal energy of the hot air sprayed from the air floating roller and increase the efficiency of additional drying.

[0077] The partitions 130 may be arranged in pairs in the transport direction (x-axis direction) of the electrode sheet 10 with the air floating rollers interposed therebetween.

[0078] Second Embodiment 6 is a schematic diagram of an electrode sheet drying apparatus according to another embodiment of the present invention. Referring to FIG. 6, a drying apparatus 200 according to the present invention includes a drying oven 210, an air floating roller 221, and a suction roller 225.

[0079] The drying oven 210 and the air floating roller 221 have been described in detail above, so a detailed description thereof will be omitted.

[0080] In the drying device 200 according to the second embodiment, a suction roller 225 is disposed downstream of the air floating roller 221.

[0081] In one specific example, the intake roller 225 may be a drive roller capable of rotating by itself. Therefore, tension can be applied to the electrode sheet depending on the difference in rotational speed between the intake roller 225 and the transfer roller 222 located downstream of the intake roller 225.

[0082] In addition, the suction roller 225 allows the electrode sheet to adhere tightly to the suction roller, so that the electrode sheet can run in a fixed position without floating up while running on the suction roller 225. In particular, in the drying device 200 according to the present invention, the position of the electrode sheet 10 may be shaken due to an external force of hot air while the electrode sheet 10 runs on the air-floating roller 221, but the suction roller 225 arranged downstream of the air-floating roller 221 adheres to the electrode sheet 10, thereby applying an appropriate tension to the electrode sheet 10 during transportation and preventing the electrode sheet from meandering.

[0083] In one embodiment, the intake roller 225 has a cylindrical outer shape, and a plurality of perforated holes or slits may be formed on the outer circumferential surface thereof to attract the electrode sheet onto the intake roller 225. The plurality of perforated holes or slits may be uniformly distributed over the entire outer circumferential surface of the intake roller 225.

[0084] A through-hole is provided inside the suction roller 225, and when a vacuum is applied to the inside of the suction roller 225 through the through-hole, the pressure difference between the inside and outside of the suction roller 225 causes outside air to flow into the inside, and the electrode sheet 10 running on the suction roller 225 can be adsorbed to the outer surface of the suction roller 225.

[0085] The shape of the perforated holes is not particularly limited, but may be one or more selected from the group consisting of a circle, an ellipse, and a polygon.

[0086] The perforated holes or slits preferably have a small area so as not to damage the electrode sheet when adsorbed by vacuum application. The length of each major axis of the perforated holes or slits may be 0.1 mm to 10 mm, preferably 0.2 mm to 7.5 mm, and more preferably 0.5 mm to 5 mm.

[0087] The drying apparatus 200 of the present invention may further include a vacuum pump (not shown) for applying a vacuum to the through-holes inside the suction roller 225 .

[0088] <Electrode sheet manufacturing system> 7 is a schematic diagram of an electrode sheet manufacturing system (hereinafter referred to as the "manufacturing system") according to one embodiment of the present invention. Referring to FIG. 7, the manufacturing system 1000 of the present invention may include a winder 200, a coating unit 300, a drying device 100, and a rewinder 400.

[0089] The manufacturing system 1000 of the present invention may continuously perform the following processes: a coating process of applying electrode slurry onto a sheet-shaped current collector; a main drying process of drying the electrode sheet coated with the electrode slurry in a drying oven; an additional drying process of additionally drying the electrode sheet that has undergone the main process; and a process of winding up the electrode sheet that has completed the drying process into a roll.

[0090] The winder 200 may be configured to continuously unwind the current collector sheet 11 wound on a roll and supply it to the coating unit 300 .

[0091] The coating units 300, 310, 320 may be configured to apply electrode slurry to one side of the current collector supplied from the winder. The coating units may include a coater 310 configured to discharge the electrode slurry onto the current collector through a discharge port, and a coating roller 320 that is paired with the coater 310 and installed at a position opposite the coater to support and transport the current collector sheet.

[0092] The drying device 100 is for drying the electrode slurry applied by the coating unit, and includes a drying oven 110 configured to perform main drying and an air floating roller 121 for additional drying, the details of which are as described above.

[0093] The rewinder 400 can be configured to wind up the electrode sheet 10 discharged from the drying device 100 into a roll.

[0094] The manufacturing system having such a configuration can be applied to a manufacturing system for a cross-sectional electrode in which electrode slurry is applied to one surface of a current collector.

[0095] A manufacturing system for a double-sided electrode in which electrode slurry is applied to both sides of a current collector may further include a coating unit and a drying unit in addition to the above manufacturing system. That is, the system may include a winder that continuously unwinds the current collector, a first coating unit that applies electrode slurry to one side of a current collector sheet supplied from the winder, a first drying unit disposed downstream of the first coating unit, a second coating unit that applies electrode slurry to the other side of the current collector sheet discharged from the first drying unit, a second drying unit disposed downstream of the second coating unit, and a rewinder that winds up the electrode sheet discharged from the second drying unit into a roll.

[0096] The manufacturing system of the present invention as described above includes a drying oven configured to perform main drying and an air-floating roller configured to perform additional drying, whereby the electrode sheet is discharged from the drying oven in a partially undried state, preventing cracks and wrinkles that may be caused by over-drying, while the air-floating roller allows the electrode sheet to be completely dried, thereby preventing contamination of transfer rollers and equipment in subsequent processes.

[0097] <How to dry the electrode sheet> 8 is a flowchart of a method for drying an electrode sheet according to one embodiment of the present invention. Referring to FIG. 8, the method for drying an electrode sheet according to the present invention includes a main drying step (S1) of drying an electrode sheet having an electrode slurry applied to a current collector in a drying oven, and an additional drying step (S2) of additionally drying the electrode sheet during transportation after the main drying step.

[0098] The drying method of the present invention is a two-step drying method including both a main drying step (S1) and an additional drying step (S2), and can use the drying apparatuses 100 and 200 described above. Specifically, the main drying step (S1) can be performed using the drying oven, and the additional drying step (S2) can be performed using an air-floating roller. The additional drying step (S2) can be performed while the electrode sheet travels over the air-floating roller configured to spray hot air onto the electrode sheet.

[0099] The main drying step (S1) and the additional drying step (S2) are continuous steps, and the main drying step (S1) and the additional drying step (S2) can be continuously performed on the electrode sheet during transportation.

[0100] In this case, the transport speed of the electrode sheet may be 10 m / min to 50 m / min, specifically 12 m / min to 40 m / min, or 15 m / min to 50 m / min, or 20 m / min to 40 m / min, or 15 m / min to 30 m / min, or 20 m / min to 30 m / min.

[0101] The main drying step (S1) may be a step of removing a substantial amount of the solvent in the electrode slurry to dry the electrode sheet but not to the extent that over-drying occurs, and the additional drying step (S2) may be a step of making up for insufficient drying.

[0102] As a result, the drying method according to the present invention has the effect of reducing the occurrence of cracks due to overdrying while enabling the electrode sheet to be completely dried before being wound up.

[0103] In the method for drying an electrode sheet according to one embodiment of the present invention, the main drying step may dry a portion of the electrode sheet so that the solvent removal rate calculated by the following formula 1 is 50% to 98%, preferably 60% to 96%, and more preferably 70% to 95%. When the solvent removal rate is within the above numerical range, the transport speed of the electrode sheet is not reduced, which is preferable in terms of productivity.

[0104] [Formula 1] Solvent removal rate (%) = (weight of electrode sheet before main drying process - weight of electrode sheet after main drying process) x 100 / (weight of electrode sheet before main drying process - weight of electrode sheet after additional drying process)

[0105] In the main drying step (S1), the drying temperature can be set to less than 170°C, preferably 80°C to 150°C, and more preferably 90°C to 130°C.

[0106] In one embodiment, the air floating roller may have a hollow cylindrical shape with a hollow interior and a plurality of air injection holes for injecting hot air onto the outer circumferential surface.

[0107] The pressure of the hot air sprayed from one air spray hole can be adjusted to 0.01 MPa to 0.5 MPa, more specifically 0.01 MPa to 0.4 MPa; 0.01 MPa to 0.3 MPa; 0.01 MPa to 0.2 MPa; 0.01 MPa to 0.1 MPa; 0.05 MPa to 0.2 MPa; 0.1 MPa to 0.5 MPa; 0.2 MPa to 0.4 MPa; 0.01 MPa to 0.09 MPa; or 0.05 MPa to 0.09 MPa.

[0108] In addition, the temperature of the hot air injected through the air injection holes can be adjusted to 50°C to 150°C, more specifically, 60°C to 140°C or 80°C to 120°C.

[0109] In the present invention, in order to enhance the drying complement effect of the air-floating roller, it is preferable that the area of ​​the air-floating roller facing the electrode sheet is as large as possible. Thus, in one specific example, the smaller the contact angle between the air-floating roller and the electrode sheet, the larger the area of ​​the air-floating roller facing the electrode sheet, and it is preferable that the contact angle between the air-floating roller and the electrode sheet is 90 degrees or less.

[0110] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations may be made by a person skilled in the art without departing from the essential characteristics of the present invention. Therefore, the drawings disclosed in the present invention are intended to explain, not to limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by such drawings. The scope of protection of the present invention should be interpreted by the scope of the claims, and all technical concepts within the equivalent range should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0111] 10: Electrode sheet 100, 200: Drying equipment 1000: Manufacturing System 110, 210: Drying oven 111: Inlet 112: Outlet 113, 213: Drying means 114, 214, 122, 222: Transfer rollers 121, 221: Air floating roller 121a: Outer surface 121b:Aperture 121c: Air injection hole 123: Tension control roller 124: Drive roller 130: Bulkhead 225: Suction roller 200: Winder 300: Coating section 400: Rewinder

Claims

1. a drying oven having an internal space for drying the electrode sheet in which the electrode slurry is applied onto the current collector; and one or more air floating rollers arranged downstream of the drying oven and configured to blow hot air onto the electrode sheet; The drying oven does not completely dry the electrode sheet, but leaves it partially undried, The electrode sheet drying device, wherein the air floating roller is positioned so that the contact angle with the electrode sheet is 90° or less.

2. The electrode sheet drying device according to claim 1 , wherein the air floating roller has a hollow cylindrical outer shape and is provided with a plurality of air injection holes on its outer circumferential surface.

3. The electrode sheet drying device according to claim 2 , wherein the diameter of the air injection holes is in the range of 0.5 mm to 15 mm.

4. The electrode sheet drying device according to claim 1 , wherein at least one of the air floating rollers is positioned to blow hot air against a first surface of the electrode sheet facing upward in the drying oven.

5. 2 . The electrode sheet drying device according to claim 1 , wherein at least one of the air floating rollers is positioned to spray hot air against a second surface of the electrode sheet facing downward in the drying oven.

6. The air floating roller is a first air floating roller positioned in the drying oven to spray hot air onto a first surface of the electrode sheet facing upward; and 2. The electrode sheet drying device according to claim 1, further comprising a second air floating roller positioned to blow hot air against a second surface of the electrode sheet facing downward in the drying oven.

7. The electrode sheet drying device according to claim 1 , wherein a suction roller is disposed downstream of the air floating roller.

8. The electrode sheet drying device according to claim 1 , wherein a partition wall is installed around the air floating roller to isolate it from an external space.

9. A winder that continuously unwinds the current collector, a coating unit that applies electrode slurry to one surface of the current collector supplied from the winder; The electrode sheet drying device according to claim 1 , which is disposed downstream of the coating unit; and a rewinder that winds up the electrode sheet discharged from the drying device;

10. a main drying process in which the electrode sheet having the electrode slurry applied onto the current collector is dried in a drying oven; and The method includes an additional drying step of additionally drying the electrode sheet during transportation after the main drying step, In the main drying step, the electrode sheet is partially dried so that the solvent removal rate calculated by the following formula 1 is 50% to 98%: [Formula 1] Solvent removal rate (%) = (weight of electrode sheet before main drying step - weight of electrode sheet after main drying step) x 100 / (weight of electrode sheet before main drying step - weight of electrode sheet after additional drying step) and the additional drying step is performed while the electrode sheet is traveling over an air-floating roller configured to spray hot air onto the electrode sheet; The method for drying an electrode sheet, wherein the air floating roller is positioned so that the contact angle with the electrode sheet is 90° or less.

11. The method for drying an electrode sheet according to claim 10 , wherein the air floating roller has a hollow cylindrical outer shape and is provided with a plurality of air injection holes for injecting hot air onto an outer circumferential surface thereof.

12. The method for drying an electrode sheet according to claim 11, wherein the pressure of the hot air injected from one air injection hole is 0.01 MPa to 0.5 MPa.

13. The method for drying an electrode sheet according to claim 11, wherein the temperature of the hot air ejected from one air ejection hole is 50°C to 150°C.

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