Sheet winding device for secondary battery manufacturing

Abstract

According to one embodiment of the present invention, there is provided a sheet winding device for manufacturing a secondary battery, which includes at least two bobbins including a running bobbin on which a winding process is performed and a standby bobbin that waits during the winding process, and a sensor disposed at a predetermined distance from the standby bobbin, the sensor detecting a mark for identifying a position where the sheet wound on the running bobbin is automatically attached to the standby bobbin. When the winding process on the running bobbin is completed, the sheet wound on the running bobbin is attached to the outer peripheral surface of the standby bobbin, and then the winding process is performed.

Description

Technical Field

[0001] [Cross - reference to Related Applications] This application claims the benefit of priority based on Korean Patent Application No. 10 - 2022 - 0142920 filed on October 31, 2022, and all the contents disclosed in the literature of the Korean patent application are included as part of this specification.

[0002] The present invention relates to an apparatus used in the winding process of a sheet for manufacturing a secondary battery. More specifically, it relates to a sheet winding apparatus for manufacturing a secondary battery that can automatically recognize the position where an electrode sheet or a separator sheet is connected to a bobbin and improve the winding performance with respect to the electrode sheet or the separator sheet.

Background Art

[0003] Recently, due to the depletion of fossil fuels, the price of energy sources has increased, and there has been a growing concern about environmental pollution. The demand for environmentally friendly alternative energy sources has become an essential factor for future life. Therefore, research on various power generation technologies such as nuclear power, solar power, wind power, and tidal power has continued, and much attention has also been paid to power storage devices for more efficiently using the energy thus produced.

[0004] Particularly, as the technology development and demand for mobile devices increase, the demand for secondary batteries as an energy source has rapidly increased, and accordingly, many studies on secondary batteries that can meet various requirements have been conducted.

[0005] There is a high demand for lithium secondary batteries such as lithium - ion batteries and lithium - ion polymer batteries, which typically have merits such as high energy density, discharge voltage, and output stability.

[0006] A secondary battery may include a positive electrode and a negative electrode. The positive electrode consists of a positive electrode current collector coated with a positive electrode active material and a plain positive electrode portion that is not coated. Similarly, the negative electrode consists of a negative electrode current collector coated with a negative electrode active material and a plain negative electrode portion that is not coated. Electrode tabs are provided on both the plain positive electrode portion and the plain negative electrode portion.

[0007] A porous separation membrane is interposed between the positive and negative electrodes. This membrane insulates the positive and negative electrodes from each other and allows for the exchange of active material ions between the electrodes, thereby triggering an electrochemical reaction.

[0008] Such secondary batteries can sometimes be classified according to the structure of the electrode assembly, which consists of a positive electrode, a negative electrode, and a separator membrane interposed between the positive and negative electrodes. Typical examples include jelly roll (wind-up type) electrode assemblies, which have a structure in which a long sheet-type positive electrode and negative electrode with a separator membrane interposed between them are wound up, and stacked (laminated type) electrode assemblies, in which a large number of positive and negative electrodes cut into units of a predetermined size are sequentially laminated with a separator membrane interposed between them. Recently, in order to solve the problems of the jelly roll electrode assemblies and stacked electrode assemblies, stack / folding type electrode assemblies have been developed as a hybrid form of the jelly roll and stacked type, in which unit cells, each with a separator membrane interposed between a predetermined unit of positive and negative electrode, are arranged on a separation film and sequentially wound up.

[0009] On the other hand, each electrode that makes up the electrode assembly is manufactured in sheet form and supplied to the secondary battery manufacturing process. Typically, the electrode sheet that has gone through the electrode manufacturing process is wound into a roll on a designated bobbin. The electrode sheet is wound onto the bobbin while being supported by a final bobbin located at the front end of the bobbin.

[0010] Referring to Figure 1, in the conventional secondary battery manufacturing sheet winding device 1, double-sided tape 30 is attached to a linear mark 20 on the bobbin 10 to which the starting portion of the electrode sheet is attached. In addition, to ensure that the starting portion of the electrode sheet is accurately attached to the mark 20 on the bobbin 10, a convex dog 50 is provided on at least one of the two mounting parts 40 on both sides of the bobbin 10 to guide the starting portion of the electrode sheet, and the dog 50 is positioned on the extension of the mark 20. The operator attaches the bobbin 10 to the secondary battery manufacturing sheet winding device 1 and rotates the dog 50 so that the mark 20 on the bobbin 10 is positioned in front of the operator. After the operator aligns the starting portion of the electrode sheet with the mark 20, the operator manually attaches the electrode sheet to the double-sided tape 30 on the surface of the bobbin 10. The electrode sheet winding process is then carried out.

[0011] There is a need to switch from such a manual, conventional sheet winding device 1 for secondary battery manufacturing to an automated process system in order to increase the convenience and efficiency of the process. [Overview of the project] [Problems that the invention aims to solve]

[0012] The present invention aims to provide a secondary battery manufacturing sheet winding device that has a structure capable of automatically recognizing the attachment position of a sheet (electrode sheet or separation membrane sheet) to a bobbin used in the winding process of secondary battery manufacturing, and automatically attaching the sheet to the bobbin and winding the sheet.

[0013] Another object of the present invention is to increase the convenience and efficiency of the process by using such a sheet winding device for secondary battery manufacturing, while also reducing the defect rate of electrode winding rolls by attaching the electrode rolls to the correct position.

[0014] However, the problems that the embodiments of the present invention aim to solve are not limited to those described above, and can be broadly expanded within the scope of the technical ideas included in the present invention. [Means for solving the problem]

[0015] A sheet winding apparatus for manufacturing secondary batteries according to one embodiment of the present invention includes at least two bobbins, including a traveling bobbin on which a winding process is performed and a standby bobbin that is on standby during the winding process, and a sensor positioned at a predetermined distance from the standby bobbin, the sensor sensing a mark for identifying a position where the sheet wound on the traveling bobbin is automatically attached to the standby bobbin, wherein when the winding process on the traveling bobbin is completed, the sheet wound on the traveling bobbin is attached to the outer surface of the standby bobbin, and the winding process is subsequently performed.

[0016] The sensor may detect the mark, thereby adjusting the position on the standby bobbin where the sheet is attached to face the sheet side.

[0017] The outer circumferential surface of the standby bobbin is provided with an adhesive portion to which the starting end of the sheet is attached, and when the sensor detects the mark, the sheet may be attached to the adhesive portion of the standby bobbin.

[0018] The system further includes a turret that supports the traveling bobbin and the standby bobbin and rotates the traveling bobbin and the standby bobbin, and after the winding process on the traveling bobbin is completed by the rotation of the turret, the winding process on the standby bobbin may be performed thereafter.

[0019] The sheet moves between the standby bobbin and the pressurizing section, is wound onto the traveling bobbin, and when the winding process on the traveling bobbin is completed, the sheet is attached to the outer surface of the standby bobbin by the pressurizing section, cut by the cutting section, and then the winding process on the standby bobbin is performed.

[0020] When the winding of the sheet on the traveling bobbin is complete, the sensor may detect the mark on the standby bobbin.

[0021] During the winding process on the running bobbin, the sensor may detect the mark on the standby bobbin in advance.

[0022] When the winding process on the running bobbin is completed, it may further include a pressing part for attaching the sheet to the outer peripheral surface of the standby bobbin.

[0023] The mark has a color distinguishable from the outer peripheral surface of the standby bobbin, and the sensor may be a laser light sensor or a color sensor.

[0024] The bonding part has a strip shape and is located along the length direction of the bobbin. The bonding part may be in contact with the mark or be separated from the mark by a predetermined distance.

[0025] The outer peripheral surface of the standby bobbin is surrounded by a film part, and the bonding part may be attached onto the film part.

[0026] The film part may be PET (polyethylene terephthalate), or PP (polypropylene), HDPE (high density polyethylene).

[0027] The mark may be a finishing tape for finishing and fixing the end of the film part.

[0028] The pressing part may be a nip roller that can reciprocate on the standby bobbin side.

[0029] It may further include a guide part for changing or guiding the moving direction of the sheet.

[0030] The guide part further includes a first guide part located on the moving path of the sheet between the running bobbin and the standby bobbin. By the first guide part, the tension of the sheet between the running bobbin and the first guide part may be maintained, and the tension between the first guide part and the standby bobbin may also be maintained.

[0031] The first guide portion may be a guide roller.

[0032] The guide section may further include a dancer roller.

[0033] The mark may be a line displayed along the entire length of the bobbin, or a set of lines or dots displayed only in part along the length of the bobbin.

[0034] The aforementioned sheet may be any one of the positive electrode sheet, negative electrode sheet, or separator membrane sheet of a secondary battery. [Effects of the Invention]

[0035] The present invention increases the convenience and efficiency of a secondary battery manufacturing process by automatically recognizing the attachment position of a sheet (electrode sheet or separation membrane sheet) to a bobbin used in the winding process and automatically attaching the sheet to the bobbin. Furthermore, even in such an automated process, the defect rate of electrode winding rolls can be significantly reduced by attaching the electrode rolls to the correct positions. [Brief explanation of the drawing]

[0036] [Figure 1] This diagram schematically shows a sheet winding device for secondary battery manufacturing that is based on conventional technology. [Figure 2] This diagram schematically shows a sheet winding device for secondary battery manufacturing according to one embodiment of the present invention. [Figure 3] Figure 2 is a front view of a sheet winding device for secondary battery manufacturing. [Figure 4] Figure 2 is a side view of a sheet winding device for secondary battery manufacturing. [Figure 5] Figure 2 is a front view of a bobbin attached to a sheet winding device for secondary battery manufacturing. [Figure 6] This is a perspective view of a bobbin according to one embodiment of the present invention. [Modes for carrying out the invention]

[0037] The present invention will be described in detail below, with reference to the attached drawings, so that various embodiments may be easily implemented by a person with ordinary skill in the art to which the invention pertains. The present invention can be embodied in various different forms and is not limited to the embodiments described herein.

[0038] Furthermore, the dimensions and thicknesses of each component shown in the drawings are arbitrary for the sake of explanation and are not necessarily limited to those shown in the present invention. The thicknesses are shown enlarged in the drawings to clearly represent various layers and regions. In addition, the thicknesses of some layers and regions are exaggerated in the drawings for the sake of explanation.

[0039] Furthermore, when we say that a layer, membrane, region, plate, or other part is "on top of" or "on top of" another part, this includes not only the case where it is "directly above" the other part, but also the case where the other part is in between. Conversely, when we say that one part is "directly above" another part, it means that there is no other part in between. Also, when we say that a part is "on top of" or "on top of" a reference part, it means that it is located above or below the reference part, and does not necessarily mean that it is located "on top of" or "on top of" in the opposite direction of gravity.

[0040] Furthermore, when a specification states that a certain part "includes" a certain component, unless otherwise specified, this means that it does not exclude other components, but rather that it can further encompass other components.

[0041] Furthermore, throughout the specification, "on a plane" means when the subject is viewed from above, and "on a cross-section" means when the subject is viewed from the side of a cross-section obtained by cutting the subject perpendicularly.

[0042] Furthermore, since the top / bottom or upper / lower parts of a particular section may be judged differently depending on the direction used as the reference, throughout the specification, "top" and "bottom" refer to two surfaces facing each other on the z-axis in that section, and "upper part" and "lower part" refer to surfaces located in opposite directions on the z-axis in that section.

[0043] Figure 2 is a schematic diagram showing a sheet winding device 100 for secondary battery manufacturing according to one embodiment of the present invention. Figure 3 is a front view of the sheet winding device 100 for secondary battery manufacturing shown in Figure 2. Figure 4 is a side view of the sheet winding device 100 for secondary battery manufacturing shown in Figure 2. Figure 5 is a front view of a bobbin 110 attached to the sheet winding device 100 for secondary battery manufacturing shown in Figure 2.

[0044] A sheet winding device 100 for secondary battery manufacturing according to one embodiment of the present invention can be used to wind (rewind) electrode sheets (positive electrode sheets or negative electrode sheets) that have undergone a series of processes such as coating and drying in the electrode manufacturing process of secondary batteries. Alternatively, it can be used to wind (rewind) separation membrane sheets. However, the present invention is not limited thereto and can be applied to a variety of environments, such as winding other films and sheets used in the electrode manufacturing process. For the sake of explanation, the case of winding electrode sheets will be described below. The following description can be similarly applied when winding other sheets such as separation membrane sheets.

[0045] Referring to Figures 2 to 5, the sheet winding device 100 for secondary battery manufacturing according to one embodiment of the present invention includes at least two bobbins 110 on which electrode sheets are wound. This embodiment shows a case in which two bobbins 110 are included.

[0046] Of the two bobbins 110, the traveling bobbin is the traveling bobbin 110a, and the standby bobbin is the standby bobbin 110b. The traveling bobbin 110a is the bobbin on which the electrode sheet is wound. The standby bobbin 110b is a bobbin that is in standby mode, and when the winding of the traveling bobbin 110a is completed, it is replaced by the traveling bobbin 110a, and the winding of the electrode sheet is carried out again in the same manner.

[0047] On the other hand, the present invention is not limited to the above, and may be equipped with multiple traveling bobbins 110a to perform the winding process simultaneously, or may be equipped with multiple standby bobbins 110b so that an operator can attach multiple standby bobbins 110b to the secondary battery manufacturing sheet winding device 100 at once, and when winding is completed on one bobbin 110, winding is then moved to the next bobbin 110, and the winding process is performed sequentially.

[0048] The outer surface of the bobbin 110 is surrounded by a film portion 120 that runs around the bobbin 110. The film portion 120 may be, for example, vinyl, or it may be, for example, PET (polyethylene terephthalate), PP (polypropylene), or HDPE (high-density polyethylene). The film portion 120 may be wrapped around the outer surface of the bobbin 110 multiple times. An adhesive portion 140 is adhered to the outer surface of the film portion 120 surrounding the bobbin 110, and the electrode sheet is then adhered again on top of the adhesive portion 140. The adhesive portion 140 may be, for example, double-sided tape. In other words, after surrounding the outer surface of the bobbin 110 with the film portion 120 (vinyl), the adhesive portion 140 (double-sided tape) is attached on top of it, and the electrode sheet is wound on top of that. In other words, the adhesive portion 140 may be provided on the outer surface of the bobbin 110 with the film portion 120 interposed in between.

[0049] This prevents the surface of the bobbin 110 from being contaminated by the adhesive portion 140, allowing the bobbin 110 to be reused repeatedly.

[0050] On the other hand, a mark 130 is provided on the outer surface of the bobbin 110 or the outer surface of the film portion 120 surrounding the bobbin 110. The position where the starting portion (starting end) of the electrode sheet is attached, that is, the position of the adhesive portion 140 described later, is determined based on the mark 130. The sensor 150 is, for example, a laser light sensor or a color sensor, and the mark 130 is a different color from the outer surface of the bobbin 110 or the film portion 120 so that the sensor 150 can sense the color. In the case of a laser light sensor, it is a laser-type photoelectric sensor that recognizes the presence or absence of the mark 130 through the intensity that is reflected back after the film portion 120 with a white background and the colored mark 130. As a result, the position of the adhesive portion 140 can be identified by sensing the position of the mark 130. The sensor 150 is placed near the bobbin 110, at a predetermined distance away from the bobbin 110.

[0051] If the film portion 120 surrounds the bobbin 110, the mark 130 may be located along the length of the bobbin 110 at the point where the film portion 120 ends. Alternatively, the mark 130 may be located on the outer surface of the bobbin 110 along the length of the bobbin 110, and the film portion 120 may be made of a transparent material.

[0052] Furthermore, there are no restrictions on the shape or form of the mark 130; it is sufficient as long as it indicates the starting point of the electrode sheet and allows the sensor 150 to detect its color. The mark 130 may be a solid line or a dotted line, a line displayed along the entire length of the bobbin 110, or a set of lines or dots displayed only in part along the length of the bobbin 110. For example, it may be a solid line extending along the entire length of the bobbin 110, or it may be a set of multiple dots displayed at various points along the length of the bobbin 110; various modifications and changes are possible.

[0053] Figure 6 is a perspective view of a bobbin according to one embodiment of the present invention. In this embodiment, the mark 130 is shown to be a finishing sticker for fixing the film portion 120.

[0054] On the other hand, the adhesive portion 140 may be attached to the entire outer surface of the bobbin 110. In this case, when the electrode sheet is wound along the adhesive portion 140 that surrounds the entire bobbin 110, if the electrode sheet is mistakenly attached to part or all of the adhesive portion 140, and the electrode sheet is attached in a way that causes it to bend or become uneven, the electrode roll R that is subsequently wound onto the bobbin 110 may not be smooth.

[0055] Referring again to Figures 2 to 5, it is preferable that the adhesive portion 140 has a strip shape with a certain width and is attached along the portion of the outer surface of the bobbin 110 where the mark 130 is located, or at a predetermined distance from the mark 130. In the latter case, as will be described later, after the electrode sheet is fixed to the adhesive portion 140 located at the mark 130, the bobbin 110 rotates while maintaining a constant tension on the electrode sheet, allowing the electrode sheet to be smoothly wound around the bobbin 110.

[0056] Figure 5 shows the case where the adhesive portion 140 is attached to a part of the outer surface of the bobbin 110 at a predetermined distance (for example, 10 mm) from the mark 130.

[0057] For example, as shown in Figure 5, the adhesive portion 140 is attached using the mark 130 as a reference. Alternatively, the worker may pre-surround the film portion 120 on the bobbin 110, attach the adhesive portion 140 on top of it, and then attach the bobbin 110 to the secondary battery manufacturing sheet winding device 100. Or, after attaching the bobbin 110 to the secondary battery manufacturing sheet winding device 100, the film portion 120 may be surrounded by a nip roller or the like provided on the secondary battery manufacturing sheet winding device 100, and the adhesive portion 140 may be attached. Various modifications and changes are possible.

[0058] Referring to Figure 2, a system in which the electrode sheet is wound onto the traveling bobbin 110a, and then similarly wound onto the standby bobbin 110b, will be explained. When the winding of the electrode sheet onto the traveling bobbin 110a is complete, the following operations are performed to attach the electrode sheet to the standby bobbin 110b.

[0059] First, the standby bobbin 110b rotates slowly, and the sensor 150 detects the mark 130 on the standby bobbin 110b, causing the mark 130 to be positioned at a predetermined location where it can come into contact with the pressurizing section 160. The pressurizing section 160 is, for example, a nip roller.

[0060] The sensor 150 may detect the color of the mark 130, thereby positioning the mark 130 to face the pressurizing section 160. Alternatively, the sensor 150 may detect the color of the mark 130, and after the standby bobbin 110b has rotated a little further for a predetermined time or to a predetermined angle, the mark 130 may be positioned to face the pressurizing section 160. This can be modified and applied in various ways depending on the diverse environments in which the present invention is implemented, such as the spacing between the standby bobbin 110b, the sensor 150, and the pressurizing section 160. The important point is that the sensor 150 can detect the mark 130, and the electrode sheet can be accurately attached to the electrode attachment position (i.e., the adhesive section 140) of the standby bobbin 110b, as will be described later.

[0061] Furthermore, the sensor 150 may detect the mark 130 on the standby bobbin 110b when the winding of the electrode sheet on the traveling bobbin 110a is complete. Alternatively, the sensor 150 may detect the mark 130 on the standby bobbin 110b in advance while the traveling bobbin 110a is winding the electrode sheet, and pre-position the electrode attachment position (i.e., the adhesive portion 140) of the standby bobbin 110b in the direction of the electrode sheet.

[0062] The electrode sheet passes between the pressurizing unit 160 and the standby bobbin 110b. The pressurizing unit 160 moves towards the standby bobbin 110b, and the pressurizing unit 160 attaches the electrode sheet to the adhesive portion 140 of the standby bobbin 110b, and then moves away from the standby bobbin 110b again. At this time, the cutting unit 170 cuts the electrode sheet along the dotted line shown in Figure 2.

[0063] Meanwhile, the turret 180 rotates 180 degrees around its central axis, and the standby bobbin 110b with the electrode sheet attached moves to the existing traveling bobbin 110a side, and begins winding the electrode sheet. For the sake of explanation, we have named them the traveling bobbin 110a and the standby bobbin 110b, but when the standby bobbin 110b moves to the traveling bobbin 110a side and begins winding the electrode sheet, the standby bobbin 110b in the previous winding step becomes the traveling bobbin 110a in the current winding step, the electrode roll wound on the traveling bobbin 110a in the previous winding step is detached and transferred to the next process, and when the new bobbin 110 is attached, it becomes the standby bobbin 110b in the current winding step.

[0064] The rotation angle of the turret 180 is not limited to those described above and can be modified or changed depending on the diverse environments in which the present invention is implemented. For example, by changing the number of bobbins 110, the position where the traveling bobbin 110a that winds the electrode sheet is attached, and the position where the standby bobbin 110b that adheres the electrode sheet to the pressurizing section 160 is attached, the invention can be modified and applied in various ways.

[0065] The secondary battery manufacturing sheet winding device 100 further includes guide sections 190 that change or guide the direction of movement of the electrode sheet. The number, type, position, etc., of the guide sections 190 are not particularly limited and can be modified and changed in various ways depending on the environment in which the present invention is implemented. The guide sections 190 may be in the form of rollers, for example. Guide rollers 190a located in the path between the traveling bobbin 110a and the standby bobbin 110b facilitate winding on the traveling bobbin 110a, while also facilitating the attachment of the electrode sheet to the standby bobbin 110b by the pressurizing section 160. Furthermore, the guide rollers 190a support the electrode sheet and maintain its tension, thereby preventing the traveling bobbin 110a and the standby bobbin 110b from unintentionally influencing each other through their respective operations. The secondary battery manufacturing sheet winding device 100 may further include dancer rollers 190c in the path of the electrode sheet.

[0066] Furthermore, the secondary battery manufacturing sheet winding device 100 includes a frame (not shown) that supports the bobbin 110 and the turret 180, and drive means (not shown) that drive components such as the bobbin 110, the turret 180, and the pressurizing unit 160, respectively.

[0067] In the manner described above, the traveling bobbin 110a and the standby bobbin 110b rotate and sequentially wind the electrode sheet.

[0068] According to the present invention described above, after the winding process on one bobbin is completed, the sheet can be automatically attached to another bobbin immediately and the winding process can be performed again, thus reducing the time required to change bobbins. This increases the production efficiency of the process.

[0069] A person with ordinary skill in the art to which the present invention belongs can make various applications and modifications within the scope of the present invention based on the above.

[0070] Although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto. Various modifications and improvements by those skilled in the art, using the basic concepts of the present invention as defined in the appended claims, also fall within the scope of the present invention. [Explanation of Symbols]

[0071] 100: Sheet winding device for secondary battery manufacturing 110: Bobbin 110a: Traveling bobbin 110b: Standby bobbin 120: Film section 130: Mark 140: Adhesive part 150: Sensor 160: Pressurized section 170: Cutting section 180: Turret 190: Guide Section

Claims

1. A device for winding up sheets for the manufacture of secondary batteries, It includes at least two bobbins, including a traveling bobbin on which the winding process is performed and a standby bobbin that waits during the winding process, The bobbin has a mark on its outer surface, and the mark identifies the position on the bobbin to which the sheet is attached. A sensor positioned at a predetermined distance from the standby bobbin, further including a sensor that detects the mark, A sheet winding apparatus for manufacturing secondary batteries, wherein, once the winding process on the aforementioned traveling bobbin is completed, the sheet is attached to the outer surface of the standby bobbin, and then the winding process is performed.

2. The sheet winding apparatus for manufacturing a secondary battery according to claim 1, wherein the sheet is one of a positive electrode sheet, a negative electrode sheet, and a separation membrane sheet of a secondary battery.

3. The sheet winding device for manufacturing secondary batteries according to claim 1, wherein when the sensor detects the mark, the position of the standby bobbin to which the sheet is attached is turned toward the sheet side.

4. The outer circumferential surface of the standby bobbin is provided with an adhesive portion to which the starting end of the sheet is attached. The sheet winding device for manufacturing secondary batteries according to claim 1, wherein when the sensor detects the mark, the sheet is attached to the adhesive portion.

5. The system further includes a turret that supports the traveling bobbin and the standby bobbin and rotates the traveling bobbin and the standby bobbin, The sheet winding apparatus for manufacturing secondary batteries according to claim 1, wherein, after the winding process on the traveling bobbin is completed by the rotation of the turret, the winding process on the standby bobbin is subsequently performed.

6. The sheet moves between the standby bobbin and the pressurizing section and is wound up by the traveling bobbin. The sheet winding apparatus for manufacturing secondary batteries according to claim 1, wherein, after the winding process on the traveling bobbin is completed, the sheet is attached to the outer surface of the standby bobbin in the pressurizing section, cut in the cutting section, and then the winding process on the standby bobbin is performed.

7. The sheet winding apparatus for manufacturing secondary batteries according to claim 1, wherein when the winding of the sheet on the traveling bobbin is completed, the sensor detects the mark on the standby bobbin.

8. The sheet winding apparatus for manufacturing secondary batteries according to claim 1, wherein the sensor detects the mark on the standby bobbin in advance during the winding process on the traveling bobbin.

9. The sheet winding apparatus for manufacturing secondary batteries according to claim 1, further comprising a pressurizing unit that adheres the sheet to the outer surface of the standby bobbin after the winding process on the traveling bobbin is completed.

10. The mark has a color that distinguishes it from the outer surface of the standby bobbin. The sheet winding apparatus for manufacturing secondary batteries according to claim 1, wherein the sensor is a laser light sensor or a color sensor.

11. The adhesive portion has a strip shape and is positioned along the length of the bobbin. The sheet winding device for manufacturing secondary batteries according to claim 4, wherein the adhesive portion is located in contact with the mark or at a predetermined distance from the mark.

12. The sheet winding device for manufacturing secondary batteries according to claim 4, wherein the outer surface of the standby bobbin is surrounded by a film portion, and the adhesive portion is attached to the film portion.

13. The sheet winding apparatus for manufacturing secondary batteries according to claim 12, wherein the film portion is made of PET (polyethylene terephthalate), PP (polypropylene), or HDPE (high-density polyethylene).

14. The sheet winding apparatus for manufacturing secondary batteries according to claim 12, wherein the mark is a finishing tape for finishing and fixing the end of the film portion.

15. The sheet winding device for manufacturing secondary batteries according to claim 9, wherein the pressurizing section is a nip roller that can reciprocate toward the standby bobbin side.

16. The sheet winding device for manufacturing secondary batteries according to claim 1, further comprising a guide section for changing or guiding the direction of movement of the sheet.

17. The guide portion further includes a first guide portion located in the movement path between the traveling bobbin and the standby bobbin of the sheet, The sheet winding apparatus for manufacturing secondary batteries according to claim 16, wherein the tension of the sheet between the traveling bobbin and the first guide portion is maintained by the first guide portion, and the tension between the first guide portion and the standby bobbin is maintained.

18. The sheet winding device for manufacturing secondary batteries according to claim 17, wherein the first guide portion is a guide roller.

19. The sheet winding apparatus for manufacturing secondary batteries according to claim 16, wherein the guide portion further includes a dancer roller.

20. The sheet winding apparatus for manufacturing secondary batteries according to claim 1, wherein the mark is a line displayed along the entire length of the bobbin, or a plurality of lines or dots displayed only in part along the length of the bobbin.

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