Reform pin

Abstract

In the reform pin according to the embodiment of the present invention, one end of the body connected to the head is provided thicker than the other end of the body, so that the contact surface with the inner surface of the electrode assembly is reduced when the pin is inserted into or removed from the electrode assembly, and the separator can be stably removed without lifting up. In addition, the reform pin according to the embodiment of the present invention has a head apex inclined to one side, so that the pin can be easily inserted into the hollow portion of the electrode assembly while avoiding the separator that has lifted up, thereby providing a high-performance and high-reliability reform pin.

Description

[Technical field]

[0001] This application claims the benefit of the filing date of Korean Patent Application No. 10-2021-0152370, filed with the Korean Intellectual Property Office on November 8, 2021, and all of the contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a reform pin, and more particularly, to a reform pin that enables a jelly-roll shape to be uniformly formed during the manufacture of an electrode assembly for a cylindrical battery. [Background technology]

[0003] Recently, as a countermeasure to the problems of environmental regulations and high crude oil prices, lithium batteries are being applied to many industrial fields, such as mobile application devices, automobiles, robots, and energy storage devices.

[0004] Such lithium batteries are generally classified into cylindrical, rectangular, and pouch types depending on the shape of the exterior material in which the electrode assembly is housed.

[0005] Among these, cylindrical batteries are provided in a battery pack (Cell To Pack, CTP) structure composed of multiple battery cells, which has the advantage that the packaging size can be reduced and mass production is possible due to standardized sizes compared to square or pouch type batteries provided in a battery pack structure composed of multiple battery modules.

[0006] On the other hand, cylindrical batteries include a jelly-roll type electrode assembly made up of a positive plate, a separator, and a negative plate.

[0007] The electrode assembly in a jelly roll configuration is provided by winding the electrode assembly around a core.

[0008] More specifically, the winding core contacts the negative electrode tab and one side of the hollow portion of the electrode assembly to serve as a support when the electrode assembly is wound up. Therefore, when the winding core is removed after the electrode assembly is wound up, the side wall of the electrode assembly that was in contact with the winding core may be separated to form a separator.

[0009] Therefore, when manufacturing the electrode assembly, a reforming process is performed as a post-process to maintain the jelly roll shape.

[0010] Generally, the reforming process is a process for forming the electrode assembly into a jelly roll shape, and is carried out in such a manner that a reforming pin is inserted into the portion from which the core has been removed, and the separator separated from the electrode assembly is pressed against the inner wall of the electrode assembly to adhere closely.

[0011] In the past, the reform process was carried out using a reform pin with a conical head, but when removing the inserted reform pin, the electrode assembly and the reform pin came into surface contact, making it difficult to remove the separator and difficult to reform in the negative electrode tab direction. Summary of the Invention [Problem to be solved by the invention]

[0012] SUMMARY OF THE PRESENT EMBODIMENT In order to solve the above problems, an object of the present invention is to provide a reform pin having high performance and high reliability. [Means for solving the problem]

[0013] In accordance with an embodiment of the present invention to achieve the above object, a reforming pin that is inserted into a hollow portion of an electrode assembly and reforms a separator formed on the inner wall of the hollow portion includes a body portion provided in a cylindrical shape having a first diameter, and a head portion provided as a three-dimensional figure having an apex formed at one end and the other end connected to one end of the body portion, and a second diameter of a circle formed by a vertical cross section at any point of the head is longer than the first diameter.

[0014] In this case, the head portion may have a vertical cross-sectional diameter that gradually becomes shorter from any point having the second diameter toward one end connected to the apex.

[0015] Also, the head portion may have a vertical cross-sectional diameter that gradually decreases from any point having the second diameter toward the other end connected to the body portion.

[0016] Additionally, the length of the second diameter may correspond to the width of the hollow portion.

[0017] The apex of the head may be located at any point within an imaginary region having a third diameter shorter than the second diameter, based on a horizontal central axis.

[0018] Meanwhile, the electrode assembly may be wound around a core in a jelly roll shape.

[0019] In addition, the reform pin according to the embodiment of the present invention may be used during the reform process of the electrode assembly. Effect of the Invention

[0020] In the reform pin according to the embodiment of the present invention, one end of the body connected to the head is provided thicker than the other end of the body, so that the contact surface with the inner surface of the electrode assembly is reduced when the pin is inserted into or removed from the electrode assembly, and the separator can be stably removed without lifting up. In addition, the reform pin according to the embodiment of the present invention has a head apex inclined to one side, so that the pin can be easily inserted into the hollow portion of the electrode assembly while avoiding the separator that has lifted up, thereby providing a high-performance and high-reliability reform pin. [Brief description of the drawings]

[0021] [Figure 1] FIG. 13 is a diagram of a reform pin inserted into an electrode assembly. [Diagram 2]FIG. 2 is a diagram of an electrode assembly wound on a winding core. [Diagram 3] 2 is a cross-sectional view of the conventional reform pin in FIG. 1 cut along the y-axis. [Figure 4] 2 is a cross-sectional view of the conventional reform pin in FIG. 1 cut along the x-axis. [Diagram 5] FIG. 2 is a diagram of a reform pin inserted into an electrode assembly according to an embodiment of the present invention. [Figure 6] 6 is a cross-sectional view of the reform pin according to the embodiment of the present invention shown in FIG. 5 cut along the y-axis. [Figure 7] 6 is a cross-sectional view of the reform pin according to the embodiment of the present invention shown in FIG. 5 cut along the x-axis. [Figure 8] FIG. 2 is a diagram of an electrode assembly wound by a reform pin according to an embodiment of the present invention. [Figure 9] FIG. 2 is a diagram of an electrode assembly in which a positive electrode tab is wound using a conventional reform pin according to a comparative example of the present invention. [Figure 10] FIG. 2 is a diagram of an electrode assembly in which a negative electrode tab is wound using a conventional reform pin according to a comparative example of the present invention. [Figure 11] FIG. 2 is a diagram of an electrode assembly in which a positive electrode tab is wound using a reform pin according to an experimental example of the present invention. [Figure 12] FIG. 2 is a diagram of an electrode assembly in which a negative electrode tab is wound using a reform pin according to an experimental example of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Since the present invention can be modified in various ways and has various embodiments, specific embodiments will be illustrated in the drawings and described in detail in the detailed description. However, it is understood that this is not intended to limit the present invention to the specific embodiments, but includes all modifications, equivalents, or alternatives within the spirit and technical scope of the present invention. Similar reference numerals are used for similar components while describing each drawing.

[0023] Terms such as first, second, A, B, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only to distinguish one component from another. For example, a first component may be named a second component, and similarly, the second component may be named a first component, without departing from the scope of the present invention. The term "and / or" includes a combination of multiple associated listed items or any item of multiple associated listed items.

[0024] When a component is referred to as being "coupled" or "connected" to another component, it should be understood that the component may be directly coupled or connected to the other component, but that there may be other components in between. In contrast, when a component is referred to as being "directly coupled" or "directly connected" to another component, it should be understood that there are no other components in between.

[0025] The terms used in this application are merely used to describe certain embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise. In this application, the terms "include" or "have" are intended to specify the presence of features, numbers, steps, operations, components, parts, or combinations thereof described in the specification, and are not intended to preclude the presence or additional possibility of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0026] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by a person of ordinary skill in the art to which the present invention belongs. Terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the meaning they have in the context of the relevant art, and should not be interpreted as having an ideal or overly formal meaning unless expressly defined in this application.

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0028] FIG. 1 is a diagram of a reform pin inserted into an electrode assembly.

[0029] Referring to FIG. 1, the reform pin is used in manufacturing a cylindrical battery having a CTP (Cell To Pack) structure.

[0030] More specifically, the reform pin is used in the reform process during the manufacture of cylindrical batteries, penetrating the hollow portion of the electrode assembly JR that has been wound into a jelly roll shape around a core, and fixing the separator that is generated by friction when the core is removed to the inner wall of the electrode assembly JR.

[0031] FIG. 2 is a diagram of an electrode assembly wound on a winding core.

[0032] 2, the electrode assembly JR is provided in a structure in which a separator is laminated between a positive electrode plate and a negative electrode plate, and is provided by being wound up in a jelly roll shape around a core. At this time, a positive electrode tab is attached to the uncoated portion of the positive electrode plate where no active layer is formed, and a negative electrode tab is attached to the uncoated portion of the negative electrode plate where no active layer is formed.

[0033] When the electrode assembly JR is wound into a jelly roll and the core is removed, at least one area of ​​the inner wall of the electrode assembly that abuts against the core is lifted up due to frictional force, and a Tae-kyung-shaped separator D can be produced.

[0034] When the electrode assembly JR is subsequently inserted into a can and a CTW process is performed, the separator D may be damaged by the insertion of a welding rod. Here, the CTW process may be a process of welding the negative electrode tab of the electrode assembly JR to the bottom of the can. Therefore, when manufacturing the electrode assembly JR, a reforming process may be performed so that the electrode assembly JR can maintain the jelly roll shape for a long period of time without damaging the separator.

[0035] 1 again, in the reforming process, a reform pin is inserted into a hollow portion H of the electrode assembly from which the core has been removed, and the taegeuk-shaped separator D is pressed toward the outer periphery of the hollow portion H to prevent damage caused by the separator lifting up. The conventional reform pin will be described below with reference to FIGS. 3 and 4.

[0036] FIG. 3 is a cross-sectional view of the conventional reform pin in FIG. 1 taken along the y-axis, and FIG. 4 is a cross-sectional view of the conventional reform pin in FIG. 1 taken along the x-axis.

[0037] 1, 3 and 4, a conventional reform pin is provided in a three-dimensional form including a cylindrical body portion B and a conical head portion T.

[0038] The conventional reform pin has a disadvantage that the diameter of the body B corresponds to the width of the hollow H, so that when the cylindrical reform pin is inserted into the hollow H of the electrode assembly, reforming is easy only for the separator near the positive electrode tab where the body B is located, and reforming efficiency is reduced near the negative electrode tab where the conical head T is located. In other words, the conventional reform pin has a disadvantage that the floating phenomenon is improved only for the separator at one end where the positive electrode tab is formed, and reforming is difficult for the separator at the other end where the negative electrode tab is formed. For example, the diameter of the conventional reform pin is made to be 3.15 pi, which is 0.25 pi difference from the winding core.

[0039] Furthermore, when the conventional reform pin is removed from the electrode assembly, the floating phenomenon of the separator D may occur again due to frictional force.

[0040] More specifically, the conventional reform pin has a body B provided in a cylindrical shape corresponding to the width of the hollow portion H, and thus comes into surface contact with the inner wall of the electrode assembly JR. In other words, since the conventional reform pin has a wide contact area with the electrode assembly JR, when the reform pin is removed from the electrode assembly for the CTW process, the floating phenomenon of the separator D may occur again due to frictional force, as occurs when the core is removed. Therefore, when using the conventional reform pin, there is a disadvantage that it is difficult to reform the electrode assembly with high reliability.

[0041] Therefore, in the present invention, a reform pin is provided that has a solid shape in which the cross-sectional diameter at any point on the head is wider than the cross-sectional diameter of the body, thereby minimizing contact with the separator when inserted into the hollow portion of the electrode assembly for the reform process, thereby enabling high-performance and high-reliability reform of the electrode assembly.

[0042] FIG. 5 is a diagram of a reform pin inserted into an electrode assembly according to an embodiment of the present invention.

[0043] 5, the reform pin according to the embodiment of the present invention can be inserted into the hollow portion of the electrode assembly to reform the positive electrode tab, the negative electrode tab, and the separator as described above. The structure of the reform pin will be described in more detail with reference to the following FIGS. 6 and 7.

[0044] Figure 6 is a cross-sectional view of the reform pin of the embodiment of the present invention in Figure 5 taken along the y-axis, and Figure 7 is a cross-sectional view of the reform pin of the embodiment of the present invention in Figure 5 taken along the x-axis.

[0045] 6 and 7, the reform pin has a body P B and head P T may include.

[0046] According to the embodiment, the reform pin has a head P T The torso P B It can be provided in larger chunk form.

[0047] The reform pin is explained in more detail by its structure: Body P B may be provided in a cylindrical shape having a first diameter R1. In this case, the first diameter R1 may be shorter than the diameter of the cross section of the hollow portion H of the electrode assembly JR.

[0048] Head P T is the torso P B To be more specific, the head P T At one end of the T The other end of the body P B One end of the can be connected.

[0049] Head P T is the torso P B In other words, the head P may include any point having a vertical cross section with a second diameter R2 that is longer than the first diameter R1. Tcan be provided as a rotating body having an arrowhead shape. For example, the second diameter R2 can be made 3.2 pi, which is 0.2 pi from the winding core.

[0050] To explain this more specifically with reference to an embodiment, the head P T can be divided into a first region A1 and a second region A2 based on a point having a second diameter R2.

[0051] The first region A1 may be a region between the apex and any point having the second diameter R2, and the second region A2 may be a region between any point having the second diameter R2 and the trunk P B It may be a region between one end of the

[0052] At this time, the head P in the first area A1 T The length of the diameter may gradually decrease from any point having the second diameter R2 toward the apex. In other words, the head P in the first region A1 T can be provided in a cone shape.

[0053] In addition, the head P in the second area A2 T is a point having a second diameter R2 from the trunk P B In other words, the length of the head P in the second region A2 may gradually decrease as it moves toward one end of the head P. T can be provided as a body of revolution whose horizontal cross section is trapezoidal.

[0054] Head P T The vertex P of the vertex P can be located at any point within an imaginary region having a third diameter R3 based on the horizontal central axis C.

[0055] According to one embodiment, the head P T The apex P of the can be located on the central axis C.

[0056] According to another embodiment, the head P T The apex P of the curve may be located offset to one side.

[0057] Therefore, the reform pin according to the embodiment of the present invention has a head P T Since the apex P of the electrode assembly JR is inclined at a predetermined angle toward one side, the separator D can be easily inserted into the S region (see FIG. 8 described below) while avoiding the separator D that caused the separator D to float when inserted into the hollow portion H of the electrode assembly JR.

[0058] On the other hand, head P T The length of the second diameter R2 at any point may correspond to the width of the hollow portion H of the electrode assembly.

[0059] FIG. 8 is a diagram of an electrode assembly wound by a reform pin according to an embodiment of the present invention.

[0060] Referring to FIG. 8, the reform pin according to the embodiment of the present invention has a head P T The size of at least one point of the torso P B Since the head P is provided larger than the head P, when the head P is inserted into the electrode assembly JR having the hollow portion H, T Due to the size of the torso P B Therefore, the reform pin according to the embodiment of the present invention has a small contact area with the electrode assembly JR and therefore friction is minimized, so that the reform pin can be stably removed from the electrode assembly JR without causing the separator D to lift up.

[0061] In addition, the reform pin according to the embodiment of the present invention can be easily inserted up to the negative electrode tab of the electrode assembly JR because the frictional force is minimized and it can be manufactured finely. Therefore, it is possible to reform the separator not only near the positive electrode tab but also near the negative electrode tab, so it is expected to have a highly efficient and reliable reform effect compared to the conventional reform pin that was only capable of reforming the separator near the positive electrode tab.

[0062] Furthermore, the reform pin according to an embodiment of the present invention can detect defects in the electrode assembly JR that occur when rotating the winding core after winding of the electrode assembly JR is completed and performing a primary reform of the internal separator of the electrode assembly JR.

[0063] More specifically, the reform pin according to the embodiment of the present invention has a head P T The size of at least one point of the torso P B Because the electrode assembly is provided larger, if the electrode assembly is defective, it may be difficult to insert it into the hollow portion H. Therefore, the reform pin according to the embodiment of the present invention can detect defects in the electrode assembly JR before assembly into the cylindrical can.

[0064] The reform pin according to the embodiment of the present invention has been described above. Hereinafter, the reform forming results of the electrode assembly of the cylindrical battery using the reform pin according to the experimental example and the comparative example of the present invention will be described in more detail.

[0065] FIG. 9 is a diagram of an electrode assembly in which a positive electrode tab is positioned, the positive electrode tab being wound using a conventional reform pin in accordance with a comparative example of the present invention, and FIG. 10 is a diagram of an electrode assembly in which a negative electrode tab is positioned, the negative electrode tab being wound using a conventional reform pin in accordance with a comparative example of the present invention.

[0066] Referring to Figures 9 and 10, when the diameter of the hollow portion of an electrode assembly reformed using a conventional reform pin was measured, the diameter near the positive electrode tab formed at the insertion end was measured to be 2.880 mm, and the diameter near the negative electrode tab was measured to be 2.538 mm.

[0067] FIG. 11 is a diagram of an electrode assembly in which a positive electrode tab is positioned, the positive electrode tab being wound using a reform pin according to an experimental example of the present invention, and FIG. 12 is a diagram of an electrode assembly in which a negative electrode tab is positioned, the negative electrode tab being wound using a reform pin according to an experimental example of the present invention.

[0068] Referring to Figures 11 and 12, when the diameter of the hollow portion of an electrode assembly reformed using a reform pin according to an embodiment of the present invention was measured, the diameter near the positive electrode tab formed at the insertion end was measured to be 2.909 mm, and the diameter near the negative electrode tab was measured to be 2.809 mm.

[0069] Comparing the reform shapes of the reform pin of the experimental example of the present invention and the conventional reform pin of the comparative example, it was confirmed that when using the reform pin of the experimental example of the present invention, the diameter of the hollow part near the positive electrode tab is expanded by about 0.030 mm compared to the reform formation using the conventional reform pin, and the separator molding is improved by 1.0%.

[0070] In addition, when using the reform pin of the experimental example of the present invention, the diameter of the hollow portion near the negative electrode tab is enlarged by about 0.268 mm compared to reform formation using a conventional reform pin, and it can be confirmed that separator molding is improved by 10.6%.

[0071] In addition, as shown in Table 1 below, the defective rate occurring during the winder reform process was confirmed using the reform pin according to the experimental example of the present invention and the conventional reform pin according to the comparative example.

[0072] [Table 1]

[0073] As shown in Table 1, when the reform pin according to the experimental example of the present invention is used, it can be confirmed that the defect rate is improved by 50% compared to when the conventional reform pin according to the comparative example is used.

[0074] The reform pin according to the embodiment of the present invention has been described above.

[0075] In the reform pin of an embodiment of the present invention, one end of the body connected to the head is provided to be thicker than the other end of the body, so that when inserted or removed from the electrode assembly, the contact area with the inner surface of the electrode assembly is reduced, allowing the separator to be removed stably without lifting up.

[0076] In addition, the reform pin according to an embodiment of the present invention has a head tip formed with a tilt to one side, thereby providing a high-performance, high-reliability reform pin that can be easily inserted while avoiding the separator that causes the floating phenomenon when inserted into the hollow portion of the electrode assembly.

[0077] Some aspects of the invention have been described in the context of an apparatus, but it may also be presented in terms of a corresponding method, where a block or apparatus corresponds to a method step or a feature of a method step. Similarly, aspects described in the context of a method may be presented in terms of a corresponding block or item or feature of a corresponding apparatus. Some or all of the method steps may be performed by (or using) a hardware apparatus, such as, for example, a microprocessor, a programmable computer, or an electronic circuit. In some embodiments, one or more of the most important method steps may be performed by such an apparatus.

[0078] Although the present invention has been described with reference to preferred embodiments thereof, those skilled in the art will understand that various modifications and variations of the present invention can be made without departing from the spirit and scope of the present invention as set forth in the following claims. [Explanation of symbols]

[0079] JR: Electrode assembly H: Hollow part of electrode assembly D: Separator C: Center of reform pin B: The body of a conventional reform pin T: The head of a conventional reform pin P: Top of reform pin head R1: Diameter of body R2: The diameter formed at the first point of the head R3: A virtual area where the vertex of the head can be located P B : The body P of the reform pin of the present invention T : Head of the reform pin of the present invention S: Region excluding the region where the separator is formed inside the hollow portion of the electrode assembly

Claims

1. A reforming pin that is inserted into a hollow portion of an electrode assembly to reform a separator formed on an inner wall of the hollow portion, The reform pin is a body provided cylindrically having a first diameter; and A head portion is provided as a three-dimensional figure having a top end and a top end connected to one end of the body portion, a second diameter of a circle formed by a vertical cross section of the head at any point is longer than the first diameter; The head portion includes: A diameter of a vertical cross section is gradually decreased from any point having the second diameter toward one end connected to the apex, The head portion includes: A diameter of a vertical cross section is gradually decreased from any point having the second diameter toward the other end connected to the body portion, The length of the second diameter corresponds to the width of the hollow portion. Reform pin.

2. The apex of the head is The reform pin according to claim 1 , which is located at any point within an imaginary area having a third diameter shorter than the second diameter, based on a horizontal central axis.

3. The reform pin of claim 1 , wherein the electrode assembly is wound in a jelly roll shape on a core.

4. The reform pin according to claim 1 , which is used during a reform process of the electrode assembly.

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