Electrode drying device and electrode drying method

Abstract

The electrode drying device of the present invention includes a shielding film unit provided to block a portion of radiant heat emitted from an infrared heater, the shielding film unit including a first shielding portion and a second shielding portion configured to shield one and the other longitudinal sides of the infrared heater, a shielding film connecting the first shielding portion and the second shielding portion and including a first connecting portion and a second connecting portion spaced apart from each other, and a base plate disposed on a bottom surface of the shielding film to support the shielding film, and the shielding film includes a bending portion bent toward an upper portion where the infrared heater is located.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0113035, filed on September 6, 2022.

[0002] The present invention relates to an electrode drying device that prevents the deflection of a shielding film installed in the electrode drying device to prevent thermal wrinkles that occur around the boundary between the coated and uncoated areas during the drying process of an electrode sheet. [Background technology]

[0003] Generally, a secondary battery is a battery that can be charged and discharged, unlike a primary battery that cannot be charged. Such secondary batteries are widely used in advanced electronic devices such as mobile phones, laptops, and camcorders.

[0004] The secondary batteries are classified into can-type secondary batteries and pouch-type secondary batteries. The can-type secondary battery includes an electrode assembly, an electrolyte, a can containing the electrode assembly and the electrolyte, and a cap assembly mounted on the opening of the can. The electrode assembly has a structure in which electrodes and separators are alternately stacked. The electrode includes a current collector and an electrode active material coated on the current collector.

[0005] Meanwhile, the method for manufacturing the electrode includes a transporting step of transporting a current collector, a coating step of applying an electrode slurry to a surface of the current collector to form an electrode mixture layer, and a drying step of drying the electrode slurry coated on the current collector by applying radiant heat from an infrared heater or spraying hot air.

[0006] During the drying step, the electrode slurry is converted from a liquid phase to a solid phase, causing shrinkage of the electrode mixture layer, resulting in increased drying stress. Referring to FIG. 1, in an electrode sheet 10 in which electrode slurry 11 is applied to a current collector 12, the boundary between the coated portion, where the electrode slurry is applied, and the uncoated portion, where the electrode slurry is not applied, is a region where significant thermal wrinkles occur. The drying speed of both side edges of the coated portion in the width direction (y-axis direction) is faster than the drying speed of the center portion of the coated portion. This difference in drying speed causes thermal wrinkles. In particular, since the current collector expands with increasing temperature, the contraction of the electrode slurry during drying, combined with the expansion of the current collector, deepens the thermal wrinkles.

[0007] To prevent this, attempts have been made to mitigate this heat wrinkle phenomenon by placing a shielding film unit 30 below the infrared heater of the electrode drying device and controlling the position and area of ​​the electrode surface exposed to the radiant heat emitted from the infrared heater. Referring to Figure 1, a shielding film unit 30 is placed below each side of the infrared heater 20, and part of the radiant heat emitted from the infrared heater 20 is blocked by the shielding film unit 30.

[0008] FIG. 2 is an enlarged view of a portion of a conventional shielding film unit. In the shielding film unit, the widthwise (y) end of the shielding film 32, which functions to block radiant heat, is a linear extension of the flat shielding film. When a shielding film with this structure is exposed to a high-temperature environment for a long period of time, the shielding film sags downward due to its own weight and thermal expansion. FIG. 3 illustrates this shielding film sag. If the shielding film sags too much, it may come into contact with the electrode slurry during drying, which can result in poor electrode quality.

[0009] Therefore, there is a need for technological development of a shielding film unit that can prevent the shielding film of the shielding film unit from bending. Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention provides an electrode drying device and an electrode drying method that prevent the deflection of a shielding film in a shielding film unit installed in an electrode drying device in order to mitigate the thermal wrinkle phenomenon that occurs around the boundary between the coated and uncoated parts of an electrode sheet, thereby ultimately improving the quality of the electrode. [Means for solving the problem]

[0011] An electrode drying device according to one embodiment of the present invention is an electrode drying device for drying an electrode sheet in which electrode slurry is applied to a sheet-shaped current collector, and includes: an infrared heater that applies radiant heat to the electrode sheet; and a shielding film unit that is provided to block a portion of the radiant heat emitted from the infrared heater, wherein the shielding film unit includes first and second shielding portions configured to shield one and the other longitudinal sides of the infrared heater; a shielding film that connects the first and second shielding portions and includes first and second connecting portions that are spaced apart from each other; and a base plate that is disposed on a bottom surface of the shielding film and supports the shielding film, and the shielding film includes a bending portion that is bent toward an upper portion where the infrared heater is located.

[0012] In an embodiment of the present invention, the shielding film may include a first bent portion formed at the first connecting portion and a second bent portion formed at the second connecting portion.

[0013] In an embodiment of the present invention, the bent portion is spaced apart from the plane of the base plate by a maximum distance of 0.1 mm to 5 mm.

[0014] In one embodiment of the present invention, the bent portion may have a width of 5 mm to 30 mm at a position spaced 1 mm to 20 mm inward from the end of the shielding film.

[0015] In an embodiment of the present invention, a cross section of the space between the bent portion and the base plate may be semicircular.

[0016] In an embodiment of the present invention, a cross section of the space between the bent portion and the base plate may be triangular.

[0017] In an embodiment of the present invention, a cross section of the space between the bent portion and the base plate may be rectangular.

[0018] In one embodiment of the present invention, the base plate may have a rectangular frame shape with a first rectangular through-hole at the center, and the ends of the two edges may be bent upward.

[0019] In one embodiment of the present invention, the shielding film may have a square frame shape with a rectangular second through-hole provided in the center.

[0020] In one embodiment of the present invention, the shielding film unit may further include a fixing clamp configured to detachably attach the shielding film unit to or around the infrared heater.

[0021] In one embodiment of the present invention, the shielding film may be made of stainless steel having a thickness of 0.5 mm to 10 mm.

[0022] In one embodiment of the present invention, the shielding membrane may be configured to be slidably coupled to the base plate.

[0023] The electrode drying apparatus according to one embodiment of the present invention may further include a conveying unit that supports and conveys the electrode sheet to be dried in one direction, and the shielding film unit may be disposed between the infrared heater and the conveying unit.

[0024] The electrode drying device according to one embodiment of the present invention may further include a hot air drying means for spraying hot air onto the electrode sheet.

[0025] The electrode drying method according to the present invention dries an electrode sheet using the electrode drying device described above. [Effects of the Invention]

[0026] The shielding film unit according to the present invention includes a curved bending portion in a portion of the shielding film, thereby improving thermal fluidity and preventing deflection of the shielding film. As a result, the drying apparatus according to the present invention can reduce electrode defects caused by deflection of the shielding film. [Brief explanation of the drawings]

[0027] [Figure 1] FIG. 10 is a conceptual diagram illustrating the necessity of a shielding film unit. [Figure 2] 1 is an enlarged view of a part of a conventional shielding film unit. [Figure 3] 1 is a diagram illustrating a problem with a conventional shielding film unit. [Figure 4] 1 is a view showing a part of a side surface of an electrode drying device according to an embodiment of the present invention. [Figure 5] 1 is a side view of an electrode drying device according to an embodiment of the present invention. [Figure 6] 1 is a front view of an electrode drying device according to an embodiment of the present invention. [Figure 7] FIG. 2 is an exploded perspective view of a shielding film unit according to an embodiment of the present invention. [Figure 8] 1 is a view showing an assembly of a shielding film unit according to an embodiment of the present invention; [Figure 9] FIG. 2 is a top view of a shielding film according to an embodiment of the present invention. [Figure 10] FIG. 1 is a top view of a base plate according to an embodiment of the present invention. [Figure 11] 1 is an enlarged view of a portion of a base plate according to an embodiment of the present invention. [Figure 12] 1 is an enlarged view of a portion of a shielding film unit according to an embodiment of the present invention. [Figure 13] 1 is a diagram of a bending portion according to an embodiment of the present invention; [Figure 14] 1 is a diagram of a bending portion according to various embodiments of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0028] Because the present invention can be modified in various ways and can take various forms, specific embodiments are shown by way of example in the drawings and described in detail herein, but it is not intended to limit the invention to the particular disclosed forms, and it is understood that the invention includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention.

[0029] 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, but 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, being "located on" can include not only being located on top, but also being located on bottom.

[0030] In this specification, the x-axis is the direction of transport of the electrode sheet, the y-axis is the width direction of the electrode sheet or the longitudinal direction of the infrared heater, and the z-axis is the direction perpendicular to the plane of the electrode sheet, which corresponds to the direction of infrared radiation or the direction of hot air injection.

[0031] The electrode drying device of the present invention will be described below.

[0032] FIG. 4 is a view showing a portion of the side of an electrode drying device according to one embodiment of the present invention, FIG. 5 is a side view of an electrode drying device according to one embodiment of the present invention, FIG. 6 is a front view of an electrode drying device according to one embodiment of the present invention, FIG. 7 is an exploded perspective view of a shielding film unit according to one embodiment of the present invention, and FIG. 8 is an assembly view of a shielding film unit according to one embodiment of the present invention.

[0033] 1 and 5, the electrode sheet 10 to be dried by the drying apparatus 100 of the present invention may include a sheet-shaped current collector 12 and an electrode slurry 11 applied to at least one surface of the current collector 12. That is, the electrode sheet 10 of the present invention is manufactured by coating one or both surfaces of a sheet-shaped current collector being transported with the electrode slurry 11, and the electrode slurry 11 of the electrode sheet 10 manufactured in this manner is dried through the electrode drying apparatus 100 of the present invention.

[0034] The electrode drying device 100 according to one embodiment of the present invention is a drying device for reducing the difference in drying between the widthwise center and both side edges of the electrode slurry and the thermal wrinkle phenomenon caused by the thermal expansion of the current collector, and may include an infrared heater 110 that applies radiant heat to the electrode sheet 10, a shielding film unit 120 that is provided to block a portion of the radiant heat emitted from the infrared heater 110, and a transport unit 130 that transports the electrode sheet to be dried in one direction while supporting it.

[0035] The infrared heater 110 may be a drying means disposed above the electrode sheet 10 in a direction perpendicular to the plane of the electrode sheet 10 (z-axis direction) and configured to emit radiant heat toward the electrode sheet 10 below. The infrared heater may include an infrared lamp (not shown) that irradiates infrared rays and a mounting base (not shown) that supports or mounts the infrared lamp. The number and shape of the infrared heater are not particularly limited. When multiple infrared heaters are included, the infrared heaters may be disposed spaced apart from each other along the electrode sheet transport direction (x-axis direction).

[0036] The shielding film unit 120 controls the position and area of ​​the region irradiated with radiant heat emitted from the infrared heater, and is installed in the vicinity of the infrared heater 110, for example, below the infrared heater 110. The size and shape of the shielding film unit 120 are not particularly limited and may have a shape corresponding to the size and shape of the infrared heater. For example, if the infrared heater is rod-shaped, the shielding film unit 120 may also be rod-shaped.

[0037] 4 and 5, if a plurality of infrared heaters 110 are arranged along the transport direction of the electrode sheet 10, the shielding film units 120 may also be arranged in pairs with the infrared heaters 110.

[0038] The transport unit 130 is a means for transporting the electrode sheet 10 in the transport direction (x-axis direction) and may include one or more transport rollers. The transport rollers support the electrode sheet and move the electrode sheet in the transport direction by rotational motion, and may further include a motor (not shown) that applies a rotational force to the transport rollers.

[0039] The electrode drying device 100 of the present invention may further include a hot air drying means 140 that sprays hot air onto the electrode sheet. The hot air drying means is not particularly limited as long as it is capable of spraying heated air toward the electrode sheet. An electrode drying device that includes a hot air drying means in addition to an infrared heater has the advantage of further improving drying efficiency.

[0040] FIG. 7 is an exploded perspective view of a shielding film unit according to one embodiment of the present invention, FIG. 8 is an assembled view of a shielding film unit according to one embodiment of the present invention, FIG. 9 is a top view of a shielding film according to one embodiment of the present invention, FIG. 10 is a top view of a base plate according to one embodiment of the present invention, FIG. 11 is an enlarged view of a portion of a base plate according to one embodiment of the present invention, FIG. 12 is an enlarged view of a portion of a shielding film unit according to one embodiment of the present invention, FIG. 13 is a view of a bending portion according to one embodiment of the present invention, and FIG. 14 is a view of a bending portion according to various embodiments of the present invention.

[0041] The shielding film unit according to the present invention will be described in detail with reference to these drawings.

[0042] The shielding film unit 120 according to one embodiment of the present invention includes a first shielding portion 122a and a second shielding portion 122b configured to shield one side and the other side of the infrared heater 110 in the longitudinal direction (y-axis direction), a shielding film 122 including a first connecting portion 122c and a second connecting portion 122d connecting the first shielding portion and the second shielding portion and spaced apart from each other, and a base plate 121 disposed on the bottom surface of the shielding film 122 to support the shielding film, and the shielding film 122 includes bending portions B1 and B2 bent toward an upper portion where the infrared heater 110 is located.

[0043] Referring to FIG. 2, the conventional shielding film 32 has a shape in which its ends are not bent and are extended linearly on a plane, whereas the shielding film 122 of the present invention includes bending portions B1 and B2 as shown in FIG. 12. The shape of such bending portions improves thermal fluidity in high temperature environments, thereby reducing the bending phenomenon of the shielding film.

[0044] 7 and 8, 10 and 11, the base plate 121 has a rectangular frame shape with a rectangular first through-hole 121h provided in the center.

[0045] The base plate 121 functions to support the shielding film 122, and the shielding film 122 is seated on the base plate 121.

[0046] In one specific example, the base plate 121 may have two edges that are bent upward to align the shielding film that is seated on the base plate. Referring to Figures 10 and 11, the rectangular base plate 121 has four edges 121a to 121d, and among these edges 121a to 121d, the ends of two edges 121c and 121d that extend parallel to the longitudinal direction (y-axis direction) of the infrared heater may be bent upward based on the direction perpendicular to the ground (z-axis direction).

[0047] The shielding film 122 mounted on the base plate 121 has a first shielding portion 122a and a second shielding portion 122b, which shield a portion of the infrared heater 110 to prevent a portion of the radiant heat emitted from the infrared heater 110 from being transmitted to the electrode sheet 10.

[0048] Referring to Figure 9, the shielding film 122 has a rectangular frame shape with a rectangular second through-hole 122h in the center, and around the second through-hole 122h, a first shielding portion 122a is located on the left side, a second shielding portion 122b is located on the right side, a first connecting portion 122c is located on the top side, and a second connecting portion 122d is located on the bottom side.

[0049] The first and second shielding portions 122a and 122b may be positioned above the electrode sheet so as to shield areas where heat wrinkles may occur, such as both side edges in the width direction (y-axis direction) of the electrode sheet or the boundary between the coated and uncoated areas. The area of ​​the first and second shielding portions 122a and 122b may be adjusted to increase or decrease the amount of radiant heat to be blocked.

[0050] The first and second connecting portions 122c and 122d are respectively disposed inside the third and fourth edges 121c and 121d of the base plate 121, have a predetermined width, and extend along the longitudinal direction (y-axis direction) of the infrared heater. The second through-hole 122h is located in the space between the first and second connecting portions 122c and 122d.

[0051] Radiant heat emitted from the infrared heater 110 passes through the second through-holes 122h and is irradiated onto the electrode sheet 10.

[0052] The shielding film is preferably made of stainless steel, which is less susceptible to thermal deformation in a high temperature environment of 100°C to 150°C, and may have a thickness of 0.5mm to 10mm.

[0053] In one specific example, the shielding membrane 122 may be slidably coupled to the base plate 121 .

[0054] According to a specific example, the shielding film 122 may include a first bending portion B1 formed at the first connecting portion 122c and a second bending portion B2 formed at the second connecting portion 122d.

[0055] The first bending portion B1 and the second bending portion B2 extend along the longitudinal direction (y-axis direction) of the shielding film 122 and may be formed in a region from one end to the other end of the first connecting portion 122c and from one end to the other end of the second connecting portion 122d, respectively. However, the embodiment of the bending portions B1 and B2 of the present invention is not limited thereto and may be implemented in various forms. For example, the bending portions B1 and B2 may be formed at the positions shown in FIG. 9 and have lengths that are 60% to 100% of the length L of the first connecting portion 122c and the second connecting portion 122d in the extension direction (y-axis length).

[0056] In addition, the bending portions B1 and B2 may be formed around the ends of the first and second shielding portions 122a and 122b in addition to the positions shown in FIG.

[0057] 12 and 13, the bending portions B1 and B2 of the present invention are spaced apart by a predetermined height in a direction perpendicular to the plane (z-axis direction) from the plane of the base plate 121. At this time, the maximum height H of the bending portions, which is the maximum distance, may be 0.1 mm to 5 mm.

[0058] 13, the bending portions B1 and B2 may be configured to have a width W of 5 mm to 30 mm at a position spaced 1 mm to 20 mm inward from the end 122f of the shielding film 122. Here, the spaced distance of 1 mm to 20 mm corresponds to D in FIG.

[0059] Referring to FIG. 13, in the bending portion according to an embodiment of the present invention, the cross section of the space between the bending portion B and the base plate 121 may be semicircular.

[0060] The bent shape of the bending portion is not limited thereto, and as shown in Fig. 14, the cross section of the space between the bending portion B and the base plate 121 may be triangular, trapezoidal, or rectangular. The rectangular shape may include both a right square and a regular square.

[0061] Referring to the above drawings, the shielding film unit 120 according to one embodiment of the present invention may further include a fixing clamp 123 configured to detachably attach the shielding film unit 120 to the infrared heater 110 or its surrounding area.

[0062] The placement position and number of the fixing clamps 123 are not particularly limited as long as they can fix the shielding film unit, but the fixing clamps 123 in one embodiment of the present invention can be provided around each of the four vertices of the base plate 121 that supports the shielding film 122 so that the rectangular shaped shielding film unit 120 can be stably fixed to the infrared heater 110 and its surrounding area.

[0063] In the method for drying electrodes according to the present invention, the electrodes are dried using the electrode drying device.

[0064] The electrode drying apparatus according to the present invention includes a bending portion in the shielding film that constitutes the shielding film unit installed to block a portion of the radiant heat emitted from the infrared heater. This has the effect of suppressing the temperature rise of the shielding film in a high-temperature environment, thereby improving the deflection phenomenon of the shielding film. Therefore, the drying apparatus and drying method according to the present invention can reduce electrode defects caused by the deflection of the shielding film.

[0065] <Experimental Example 1: Measurement of maximum deflection length of shielding film>

[0066] <Comparative Example> The shielding film unit including the conventional shielding film shown in FIG. 2 was placed in an electrode drying device, and the electrode sheet was dried for 30 days.

[0067] Thereafter, the shielding film unit was removed, and the maximum deflection length of the portion of the shielding film that was deflected below the height of the base plate was measured. The results are shown in Table 1.

[0068] <Example> As shown in FIG. 12, the shielding film unit including the shielding film having the bent portion formed therein was placed in an electrode drying device, and the electrode sheet was dried for 30 days.

[0069] Thereafter, the shielding film unit was removed, and the maximum deflection length of the portion of the shielding film that was deflected below the height of the base plate was measured. The results are shown in Table 1.

[0070] <Experimental Example 2: Heat flow measurement> DT_max was measured for each of the shielding films of the comparative examples and examples, and the results are shown in Table 1. DT_max refers to the maximum temperature difference across the entire volume of the shielding film, and a smaller DT_max indicates better thermal flow.

[0071] [Table 1]

[0072] Referring to Table 1, it can be seen that the shielding film including the bending portion according to the present invention has improved thermal fluidity and has the effect of reducing the deflection of the shielding film due to the accumulation of drying time. Therefore, it is expected that the electrode drying device according to the present invention has the effect of reducing the risk of electrode quality defects. [Explanation of symbols]

[0073] 10: Electrode sheet 11: Electrode slurry 12: Current collector 20: Infrared heater 30: Shielding membrane unit 100: Electrode drying device 110: Infrared heater 120: Shielding membrane unit 121: Base plate 121h: 1st through hole 122: Shielding membrane 122a: First shielding part 122b: Second shielding part 122c: 1st connection part 122d: 2nd connection part B1: First bending section B2: Second bending section 123: Fixing clamp 130:Transfer section 140:Hot air drying means

Claims

1. An electrode drying device that dries an electrode sheet in which electrode slurry is applied to a sheet-shaped current collector, an infrared heater that applies radiant heat to the electrode sheet; a shielding film unit provided to block a portion of the radiant heat emitted from the infrared heater, The shielding film unit is a first shielding portion and a second shielding portion configured to shield one side and the other side of the infrared heater in a longitudinal direction; a shielding film including a first connecting portion and a second connecting portion that connect the first shielding portion and the second shielding portion and are spaced apart from each other; a base plate disposed on a bottom surface of the shielding film to support the shielding film; The electrode drying device, wherein the shielding film includes a bending portion that is bent toward an upper portion where the infrared heater is located.

2. The shielding film is a first bending portion formed on the first connecting portion; The electrode drying device according to claim 1 , further comprising: a second bending portion formed in the second connecting portion.

3. The electrode drying device according to claim 1 , wherein the bent portion is spaced apart from the plane of the base plate, and a maximum distance between the bent portion and the plane of the base plate is 0.1 mm to 5 mm.

4. The electrode drying device according to claim 1 , wherein the bent portion has a width of 5 mm to 30 mm at a position spaced 1 mm to 20 mm inward from the end of the shielding film.

5. The electrode drying device according to claim 1 , wherein a cross section of the separation space between the bent portion and the base plate is semicircular.

6. The electrode drying device according to claim 1 , wherein a cross section of the space between the bent portion and the base plate is triangular.

7. The electrode drying device according to claim 1 , wherein a cross section of the space between the bent portion and the base plate is rectangular.

8. 2. The electrode drying device according to claim 1, wherein the base plate has a rectangular frame shape with a rectangular first through-hole at the center, and the ends of two edges of the rectangular frame-shaped base plate are each bent upward.

9. The electrode drying device according to claim 1 , wherein the shielding film has a rectangular frame shape with a rectangular second through-hole provided in the center.

10. The electrode drying device according to claim 8 , wherein the shielding film unit further includes a fixing clamp configured to attach and detach the shielding film unit to and from the infrared heater.

11. 2. The electrode drying device according to claim 1, wherein the shielding film is made of a stainless steel material having a thickness of 0.5 mm to 10 mm.

12. The electrode drying device according to claim 1 , wherein the shielding membrane is configured to be slidably coupled to the base plate.

13. The drying device further includes a transport unit that transports the electrode sheet to be dried in one direction while supporting the electrode sheet, The electrode drying apparatus according to claim 1 , wherein the shielding film unit is disposed between the infrared heater and the transport unit.

14. 2. The electrode drying device according to claim 1, further comprising hot air drying means for spraying hot air onto the electrode sheet.

15. A method for drying electrodes using the electrode drying device according to claim 1.

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