Pouch folding device for secondary batteries and secondary batteries

Abstract

The present invention relates to a pouch folding device for a secondary battery and a secondary battery. The pouch folding device for a secondary battery according to the present invention is a pouch folding device for a secondary battery that folds a pouch including a main body in which an electrode assembly is accommodated and a sealing part formed along an edge of the main body, and includes a side folding part that side-folds the sealing part of the pouch toward the main body, and a corner folding part including a corner folding roller that pressurizes a corner portion of the side-folded sealing part to corner-fold the pouch toward the main body, the corner folding roller including a flat surface and an inclined surface formed on a pressing surface, and when pressing, the inclined surface of the corner folding roller is located at a position closer to the main body than the flat surface.

Description

【Technical Field】 【0001】 This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0025558 filed on February 25, 2022, and Korean Patent Application No. 10-2023-0023905 filed on February 22, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference in their entirety. 【0002】 The present invention relates to a pouch folding device for secondary batteries and a secondary battery. 【Background Art】 【0003】 Unlike primary batteries, secondary batteries are rechargeable and have been the subject of much research and development in recent years due to their potential for miniaturization and increased capacity. With the development of technology and the increasing demand for mobile devices, the demand for secondary batteries as an energy source has been rapidly increasing. 【0004】 Secondary batteries can be classified into coin-type batteries, cylindrical batteries, prismatic batteries, and pouch-type batteries according to the shape of the battery case. In a secondary battery, an electrode assembly mounted inside the battery case is a power generation element capable of charge and discharge, which is composed of a laminated structure of electrodes and separators. 【0005】 The electrode assembly can be generally classified into a jelly-roll type in which a separator is interposed between sheet-type positive and negative electrodes coated with an active material and wound, a stack type in which unit cells each having at least one electrode and at least one separator laminated are sequentially laminated, and a stack / folding type in which unit cells are wound with a long separation film. 【0006】 When manufacturing a secondary battery, a process of bending the corner portion of a pouch containing an electrode assembly is performed. In the process of bending the corner portion of the pouch, problems occur in the insulation quality when pressing the pouch with a tool. 【0007】 More specifically, the pouch has a cup portion, which is the main body that houses the electrode assembly, and a sealing portion formed along the edge of the cup portion. Here, the sealing portion is flat, while the cup portion, which houses the electrode assembly, is not flat but has a convex three-dimensional shape relative to the sealing portion. 【0008】 To fold the pouch multiple times, the tool needs to be attached towards the cup portion. However, if the cup portion is pressed with a flat tool while it is still unsealed, it can be damaged, posing a risk to the insulation quality. [Overview of the Initiative] [Problems that the invention aims to solve] 【0009】 One aspect of the present invention is to provide a pouch folding device for secondary batteries and a secondary battery that can ensure insulation quality during pouch folding. [Means for solving the problem] 【0010】 A pouch folding device for a secondary battery according to an embodiment of the present invention is a pouch folding device for a secondary battery that folds a pouch including a main body containing an electrode assembly and a sealing portion formed along the edge of the main body, comprising: a side folding portion that side-folds the sealing portion of the pouch toward the main body; and a corner folding portion including a corner folding roller that pressurizes the corner portion of the side-folded sealing portion and corner-folds it toward the main body, wherein the corner folding roller includes a flat surface and an inclined surface formed on the pressurizing surface, and when pressurized, the inclined surface on the corner folding roller can be positioned further adjacent to the main body than the flat surface. 【0011】 On the other hand, the secondary battery according to the embodiment of the present invention may be a secondary battery manufactured by the pouch folding device for secondary batteries according to the embodiment of the present invention. [Effects of the Invention] 【0012】 According to the present invention, by using a corner folding roller with an inclined surface, the corners of the pouch can be folded, preventing insulation quality risk from occurring in the non-flat portion of the pouch where the electrode assembly is housed. Specifically, the flat surface of the corner folding roller with a constant diameter pressurizes the sealing area of ​​the flat pouch, while the inclined surface pressurizes the non-sealed area of ​​the pouch where the electrode assembly is housed, thereby preventing damage to the non-sealed area of ​​the pouch and ensuring insulation quality. [Brief explanation of the drawing] 【0013】 [Figure 1] This is a plan view illustrating the process of how the electrode assembly is housed in the pouch before the pouch is folded. [Figure 2] This is a front view showing the process by which a pouch is side-folded via a side-folding section in a pouch folding device for secondary batteries according to an embodiment of the present invention. [Figure 3] This is a perspective view showing a pouch that has been side-folded via a pouch folding device for secondary batteries according to an embodiment of the present invention. [Figure 4] This is a perspective view showing the corner folding section of a pouch folding device for secondary batteries according to an embodiment of the present invention. [Figure 5] This is a perspective view showing the folding roller and roller moving part in a pouch folding device for secondary batteries according to an embodiment of the present invention. [Figure 6] This is a front view showing a corner folding roller in a pouch folding device for secondary batteries according to an embodiment of the present invention. [Figure 7] This is a perspective view of the main part illustrating the concept of corner folding in a pouch folding device for secondary batteries according to an embodiment of the present invention. [Figure 8] This is a perspective view of the main part showing a corner-folded pouch in a pouch folding device for secondary batteries according to an embodiment of the present invention. [Modes for carrying out the invention] 【0014】 The object, particular advantages, and novel features of the present invention will become more apparent from the accompanying drawings, the following detailed description, and preferred embodiments. It should be noted that, in assigning reference numerals to components in each drawing herein, the same component will, to the greatest extent possible, have the same number even if shown in different drawings. Furthermore, the present invention can be realized in a variety of different forms and is not limited to the embodiments described herein. In describing the present invention, detailed descriptions of related prior art that could obscure the gist of the invention are omitted. 【0015】 Figure 1 is a plan view illustrating the process of housing the electrode assembly in the pouch before folding the pouch; Figure 2 is a front view showing the process of side-folding the pouch via the side-folding section in a pouch folding device for secondary batteries according to an embodiment of the present invention; Figure 3 is a perspective view showing the pouch in a side-folded state via the pouch folding device for secondary batteries according to an embodiment of the present invention; and Figure 4 is a perspective view showing the corner-folding section in a pouch folding device for secondary batteries according to an embodiment of the present invention. 【0016】 Referring to FIGS. 1 to 4, a pouch folding device for a secondary battery according to an embodiment of the present invention is a pouch folding device for a secondary battery that folds a pouch 10 including a main body 12 in which an electrode assembly 20 is accommodated and a sealing portion 13, and includes a side folding portion SR that side-folds the sealing portion 13 of the pouch 10 in the direction of the main body 12, and a corner folding portion CR including a corner folding roller 110 that pressurizes a corner portion 14 with the side-folded sealing portion 13 and corner-folds it in the direction of the main body 12. 【0017】 More specifically, referring to FIG. 1, a secondary battery 1 applied to a pouch folding device for a secondary battery according to an embodiment of the present invention includes an electrode assembly 20 and a pouch 10 that houses the electrode assembly 20 in an internal accommodation portion 11. Further, the secondary battery 1 may further include an electrode lead 30 connected to the electrode assembly 20 and extending outside the pouch 10. The electrode lead 30 can extend in the length direction of the secondary battery 1. Here, the length direction of the secondary battery 1 can be, for example, the Y-axis direction as shown in FIG. 1. 【0018】 The pouch 10 includes a main body 12 in which the electrode assembly 20 is accommodated and a sealing portion 13 formed along the edge of the main body 12. 【0019】 Here, the sealing portion 13 is formed in a flat shape, and the main body 12 is formed in a three-dimensional shape that is convex with respect to the sealing portion 13 with the electrode assembly 20 accommodated therein. 【0020】 The electrode assembly 20 can be formed in a form in which electrodes and separators are alternately laminated and aggregated. Here, the electrode assembly 20 is a power generation element capable of charge and discharge. 【0021】 The electrodes include a positive electrode and a negative electrode, and in the electrode assembly 20, the positive electrode, the separator, and the negative electrode can be alternately laminated. Here, the separator separates the positive electrode and the negative electrode and electrically insulates them. 【0022】 The positive electrode can include a positive electrode current collector and a positive electrode active material laminated on the positive electrode current collector. 【0023】 The positive electrode current collector can be made of a foil of aluminum material. 【0024】 The positive electrode active material can be composed of lithium manganese oxide, lithium cobalt oxide, lithium nickel oxide, lithium iron phosphate, or a compound and mixture containing one or more of these. 【0025】 The negative electrode can include a negative electrode current collector and a negative electrode active material laminated on the negative electrode current collector. 【0026】 The negative electrode current collector can be made of, for example, a foil made of copper (Cu) material. 【0027】 The negative electrode active material can be a compound or mixture containing a carbonaceous material. 【0028】 The separator is made of an insulating material and electrically insulates between the positive electrode and the negative electrode. Here, the separator can be formed of a polyolefin-based resin film such as polyethylene or polypropylene having microporosity. 【0029】 Referring to FIGS. 2 and 3, the side folding portion SR can side-fold the sealing portion 13 of the pouch 10 in the direction of the main body 12. 【0030】 The side folding section SR can fold the sealing sections 13 located on both sides of the pouch 10 toward the main body 12. Here, the side folding section SR can side-fold the sealing sections 13 located on both sides of the pouch 10 toward the main body 12 in the width direction of the pouch 10. Here, the width direction of the pouch 10 can be the lateral direction with respect to the length direction of the pouch 10 from which the electrode leads 30 connected to the electrode assembly 20 extend. That is, referring to Figure 3, the width direction of the pouch 10 can be the X-axis direction. Also, the width direction of the pouch 10 can be the same direction as the width direction of the secondary battery 1. 【0031】 Furthermore, the side folding section SR allows both sides of the sealing section 13 of the pouch 10 to be folded at a right angle. 【0032】 The side folding section SR can be composed of, for example, a side folding roller. Here, the sealing section 13 of the pouch 10 can be pressed on both sides via the side folding roller to cause folding. However, in the secondary battery pouch folding device according to an embodiment of the present invention, the side folding section SR is not necessarily limited to a side folding roller, and various folding tools can be used. For example, multiple folding blocks can be alternately pressed on the sealing section 13 of the pouch 10 to cause folding. 【0033】 Figure 5 is a perspective view showing the folding roller and roller moving part in a pouch folding device for secondary batteries according to an embodiment of the present invention, and Figure 6 is a front view showing the corner folding roller in a pouch folding device for secondary batteries according to an embodiment of the present invention. Furthermore, Figure 7 is a perspective view of the main part illustrating the concept of corner folding in a pouch folding device for secondary batteries according to an embodiment of the present invention, and Figure 8 is a perspective view of the main part showing a corner-folded pouch in a pouch folding device for secondary batteries according to an embodiment of the present invention. 【0034】 Referring to Figures 4 to 8, the corner folding section CR may include a corner folding roller 110 that pressurizes the corner portion 14 with the side-folded sealing section 13 and folds the corner in the direction of the main body 12. 【0035】 Referring to Figures 4 and 5, the corner folding section CR can corner-fold the pouch 13 by moving the corner folding roller 110 from the outer edge toward the center of the pouch 10 so that the corner portion 14 of the side-folded sealing section 13 is in close contact with the outer surface of the pouch 10. Furthermore, after the pouch 10 is positioned parallel to the XY plane, the corner folding section CR can corner-fold the sealing section 13 by moving the corner folding roller 110 in the X-axis direction, which is the width direction of the pouch 10. 【0036】 Referring to Figures 6 and 7, the corner folding roller 110 can include a flat surface 112 and an inclined surface 111 formed on the pressurizing surface 113. Here, the inclined surface 111 can be formed at the end of the corner folding roller 110. That is, the outer circumferential surface portion of the corner folding roller 110 that pressurizes the pouch 10 can include a flat surface 112 formed with a constant diameter and an inclined surface 111 formed so that the diameter decreases towards the end. Also, when pressurized, the inclined surface 111 of the corner folding roller 110 can be located even closer to the main body 12 than the flat surface 112. 【0037】 Here, when the corner portion 14 of the sealing portion 13, which is side-folded via the corner folding roller 110, is pressurized, the inclined surface 111 can be positioned at the portion of the corner portion 14 that is folded so as to contact the main body 12. More specifically, the flat surface 112 pressurizes the first portion 14a at the corner portion 14 of the pouch 10, and the inclined surface 111 pressurizes the second portion 14b at the corner portion 14 of the pouch 10, causing the corner portion 14 of the pouch 10 to fold. In other words, the corner folding section CR pressurizes the corner portion 14 of the sealing section 13, and during corner folding, the first portion 14a, which is pressed against the flat surface 112 of the corner folding roller 110 at the corner portion 14, folds so as to come into contact with the portion 13a located in the longitudinal direction of the pouch 10 at the sealing section 13, and the second portion 14b, which is pressed against the inclined surface 111 of the corner folding roller 110 at the corner portion 14, folds so as to come into contact with the main body 12. 【0038】 Here, the flat surface 112 folds the first portion 14a at the corner portion 14, pressurizing the flat sealing area of ​​the pouch 10, and the inclined surface 111 folds the second portion 14b at the corner portion 14, housing the electrode assembly 20, and pressurizing the non-sealing area of ​​the non-flat pouch 10. Here, the sealing area of ​​the pouch 10 that is pressurized is the portion of the sealing portion 13 that extends in the longitudinal direction of the secondary battery 1, and the non-sealing area of ​​the pouch 10 can be the portion of the main body 12 of the pouch 10. Here, the portion of the main body 12 of the pouch 10 that is pressurized by the inclined surface 111 of the corner folding roller 110 can be, for example, the terrace portion. Here, the terrace portion can be the portion of the main body 12 that does not come into contact with the electrode assembly 20. In other words, it can be the portion of the pouch 10 located in the storage section 11 of the pouch 10, in the empty space between the end of the electrode assembly 20 and the sealing section 13 of the pouch 10. Here, the terrace portion can form an incline. 【0039】 Furthermore, when the corner folding roller 110 is pressurized at the corner portion 14 of the sealing portion 13 of the side-folded pouch 10, the inclined surface 111 can be positioned on the side adjacent to the main body 12 relative to the flat surface 112. Here, the inclined surface 111 of the corner folding roller 110 can be formed with a slope such that the width of the end narrows towards the tip of the end. Here, the inclination angle α of the inclined surface 111 can be formed to be, for example, 20 to 50°. Here, the inclination angle α of the inclined surface 111 can be the inclination angle of the inclined surface 111 with respect to a virtual extension line extending from the flat surface 112. 【0040】 Therefore, the inclination angle α of the inclined surface 111 is formed to be 20° or more, and the effect on insulation quality can be significantly improved. That is, with a flat cylindrical pressure roller without an inclined surface 111, when pressurizing the terrace portion, which is the non-sealed area of ​​the pouch 10 that is not flat and houses the electrode assembly 20, the corner portion of the pressure roller may damage the non-sealed area of ​​the pouch 10, potentially reducing insulation quality. However, in the pouch folding device for secondary batteries according to an embodiment of the present invention, the inclination angle α of the inclined surface 111 of the corner folding roller 110 is formed to be 20° or more, and when pressurizing the corner portion 14 of the sealing portion 13 of the pouch 10, it is possible to pressurize without damaging the terrace portion, which is the non-sealed area of ​​the pouch 10 that is not flat. This prevents damage to the non-sealed area of ​​the pouch 10 and ensures insulation quality. 【0041】 Furthermore, forming the inclination angle α of the inclined surface 111 to 50° or less has the effect of adjusting the degree of pouch folding to the desired shape. In other words, when the inclination angle α of the inclined surface 111 is 50° or more, the effect on folding may be significantly reduced. Ultimately, when the inclination angle α of the inclined surface 111 is 50° or more, the inclined surface 111 may not be able to pressurize the non-sealed area of ​​the pouch 10 that is not flat, or the pressurizing force may be significantly reduced, preventing sufficient folding of the corner portion 14 of the sealing portion 13 of the pouch 10. This can lead to damage to the non-sealed area of ​​the pouch 10 due to the corner between the inclined surface 111 and the flat surface 112, potentially reducing the insulation quality. 【0042】 On the other hand, the length L2 of the flat surface 112 can be formed to be, for example, 2 mm or more. This ensures that the length L2 of the flat surface 112 in the corner folding roller 110 is 2 mm or more, enabling corner folding of the sealing portion 13 of the side-folded pouch 10. 【0043】 On the other hand, for example, in the corner folding roller 110, the orthogonal projection length L1 of the inclined surface 111 can be formed to be longer than the length L2 of the flat surface 112. Furthermore, in the corner folding roller 110, the orthogonal projection length L1 of the inclined surface 111 can be formed to be 400% or less of the length L2 of the flat surface 112. 【0044】 On the other hand, the corner folding roller 110 may further include a roller shaft 114. The roller shaft 114 may consist of the rotation axis of the corner folding roller 110. 【0045】 On the other hand, when corner folding of the sealing portion 13 of the pouch 10 via the corner folding roller 110, this can be done, for example, at room temperature, but the method of implementing the pouch folding device for secondary batteries according to the embodiment of the present invention is not necessarily limited to this. 【0046】 On the other hand, in the folding device for the secondary battery pouch 10 according to an embodiment of the present invention, the corner folding section CR may further include a roller moving section 120, a lower support section 130, an upper support section 140, and a support frame 150. 【0047】 The roller moving section 120 is equipped with a corner folding roller 110 and can move the corner folding roller 110. The roller moving section 120 can move the corner folding roller 110 along the X-axis direction from the outer edge of the pouch 10 toward the center. 【0048】 The lower support section 130 can support the lower part of the pouch 10 when it is corner-folded. The lower support section 130 consists of multiple blocks and can support the lower end of the main body 12 of the pouch 10. 【0049】 The upper support portion 140 can support the top of the pouch 10 during corner folding. The upper support portion 140 can be positioned on the opposite side between the corner folding roller 110 and the pouch 10 when the pouch 10 is pressurized via the corner folding roller 110. This allows the pouch 10 to be supported when the pouch 10 is pressurized via the corner folding roller 110, making the folding operation easier. 【0050】 The support frame 150 can support each device of the corner folding section CR. 【0051】 Referring to Figures 5 and 6, the pouch folding device for secondary batteries according to the embodiment of the present invention configured as described above uses a corner folding roller 110 with an inclined surface 111 to fold the corner portion 14 of the pouch 10, preventing insulation quality risk from occurring in the non-flat portion of the pouch 10 where the electrode assembly 20 is housed. Specifically, the flat surface 112 with a constant diameter on the corner folding roller 110 pressurizes the sealing area of ​​the flat pouch 10, and the inclined surface 111 pressurizes the non-sealed area of ​​the non-flat pouch 10 where the electrode assembly 20 is housed, thereby preventing damage to the non-sealed area of ​​the pouch 10 and ensuring insulation quality. 【0052】 On the other hand, referring to Figures 1, 7, and 8, a secondary battery 1 can be manufactured via a pouch folding device for secondary batteries according to an embodiment of the present invention. 【0053】 In other words, the secondary battery according to the embodiment of the present invention is a secondary battery 1 manufactured via the secondary battery pouch folding device according to the embodiment of the present invention described above. 【0054】 The secondary battery 1 is installed in the pouch 10 with the corner portion 14 folded and bent toward the main body at the sealing portion 13. 【0055】 The folded corner portion 14 includes a first portion 14a that is pressed and folded against the flat surface 112 of the corner folding roller 110, and a second portion 14b that is pressed and folded against the inclined surface 111. 【0056】 The first portion 14a forms a flat portion, and the second portion 14b forms an inclined portion that is inclined relative to the first portion 14a. 【0057】 The second portion 14b can be formed at an inclination of 20 to 50 degrees with respect to the imaginary extension of the first portion 14a. 【0058】 <Manufacturing example> We manufactured a pouch folding device for secondary batteries that folds a pouch including a main body containing an electrode assembly and a sealing portion formed along the edge of the main body. 【0059】 The aforementioned pouch folding device for secondary batteries was manufactured to include a corner folding section that pressurizes the corner portion of the side-folded sealing section and folds it toward the main body. 【0060】 The corner folding section is composed of a corner folding roller that includes a flat surface and an inclined surface formed on the pressure surface. 【0061】 The corner folding roller was manufactured in such a way that when pressurized, the inclined surface can be positioned on the side adjacent to the pouch body. 【0062】 Furthermore, as shown in Figure 6, the corner folding roller was designed with a flat surface 112 length L2 of 2 mm and an orthogonal projection length L1 of the inclined surface 111 of 3.5 m. The inclination angle α of the inclined surface 111 was set to 25°. 【0063】 <Comparative Example> A pouch folding device for secondary batteries was manufactured using the same method as the example, except that the corner folding rollers had all their pressure surfaces formed into flat surfaces. 【0064】 <Example of experiment> In secondary batteries manufactured using pouch folding devices for secondary batteries according to the examples and comparative examples, the IR (resistance) failure rate and IV (voltage) failure rate of the corner folding portion of the pouch were measured using 100 MOhm as the standard. 【0065】 Here, a rechargeable battery with a sealing width of 2 mm in a pouch was corner-folded. 【0066】 [Table 1] 【0067】 As shown in Table 1, the IR defect rate in the comparative example was 8.2%, while in the manufactured example it was significantly reduced to 1.7%. Furthermore, the IR defect rate in the comparative example was 3.45%, while in the manufactured example it was significantly reduced to 0.0%. Therefore, it can be seen that the insulation defect rate was significantly reduced in the manufactured example compared to the comparative example. 【0068】 Although the present invention has been described in detail above with reference to specific examples, this is for illustrative purposes only and does not limit the present invention to these examples. It can be said that various implementations are possible within the technical concept of the present invention by persons with ordinary skill in the art. 【0069】 Furthermore, the specific scope of protection of the invention will be clarified by the attached claims. [Explanation of symbols] 【0070】 1 Secondary battery 10 pouches 11. Storage Unit 12 Main unit 13. Sealing section 14 Corner section 14a Part 1 14b Part 2 20 Electrode assembly 30 electrode leads 110 Corner Folding Roller 111 Slope 112 Flat surface 113 Pressure surface 114 Roller shaft 120 Roller moving part 130 Lower support part 140 Upper support part 150 Support Frame SR Side Folding Section CR Corner Folding Section

Claims

[Claim 1] A pouch folding device for secondary batteries that folds a pouch including a main body containing an electrode assembly and a sealing portion formed along the edge of the main body, The sealing portion of the pouch is side-folded in the width direction of the pouch, The sealing portion, which is side-folded, includes a corner folding section which includes a corner folding roller that pressurizes the corner portion and causes the pouch to be corner-folded in the longitudinal direction, The corner folding roller includes a flat surface and an inclined surface formed on the pressurizing surface, A pouch folding device for secondary batteries, wherein, when pressurized, the inclined surface of the corner folding roller is located further adjacent to the main body than the flat surface. [Claim 2] The pouch folding device for a secondary battery according to claim 1, wherein the side folding portion folds the sealing portion located on both sides of the pouch in the width direction of the pouch. [Claim 3] The pouch folding device for a secondary battery according to claim 2, wherein the width direction of the pouch is perpendicular to the length direction of the pouch from which the electrode leads connected to the electrode assembly extend. [Claim 4] The pouch folding device for a secondary battery according to claim 3, wherein the corner folding section moves the corner folding roller from the outer edge of the pouch, which is in the direction of the main body, toward the central part, and brings the corner portion of the side-folded sealing section into close contact with the outer surface of the pouch. [Claim 5] The corner folding section, when performing corner folding while applying pressure to the corner portion, The pouch folding device for a secondary battery according to claim 4, wherein the first portion that is pressed against the flat surface of the corner folding roller at the corner portion folds so as to contact the portion located at the longitudinal end of the pouch at the sealing portion, and the second portion that is pressed against the inclined surface of the corner folding roller at the corner portion folds so as to contact the main body. [Claim 6] The pouch folding device for secondary batteries according to claim 1, wherein the inclined surface is located at the end of the corner folding roller. [Claim 7] The pouch folding device for secondary batteries according to claim 6, wherein the inclined surface of the corner folding roller is formed to become narrower towards the tip. [Claim 8] The pouch folding device for secondary batteries according to claim 7, wherein the inclination angle of the inclined surface is formed to be 20 to 50 degrees. [Claim 9] The aforementioned corner folding section is The pouch folding device for a secondary battery according to claim 1, further comprising a roller moving section to which the corner folding roller is attached and to which the corner folding roller is moved. [Claim 10] The aforementioned corner folding section is The pouch folding device for a secondary battery according to claim 1, further comprising a lower support portion that supports the lower part of the pouch when corner folding. [Claim 11] The aforementioned corner folding section is The pouch folding device for a secondary battery according to claim 1, further comprising an upper support portion that supports the upper part of the pouch when corner folding.

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