Manufacturing method for electrode assemblies

Abstract

The present invention relates to a method for manufacturing electrode assemblies, and moreover, to a method for manufacturing electrode assemblies that can improve upon the limitations of conventional lamination technology, secure freedom in cell design (such as freedom in tab position design), solve the problem of separator folding, and prevent problems such as uncut separators due to process tolerances.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0101553 filed on August 3, 2023, and Korean Patent Application No. 10-2024-0098745 filed on July 25, 2024, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference as part of this specification.

[0002] The present invention relates to a method for manufacturing an electrode assembly. Conventionally, it is possible to improve the limitations of lamination technology to ensure the degree of freedom in cell design (such as the degree of freedom in tab position design), solve the problem of folding of the separator, and prevent problems such as uncutting of the separator due to process tolerances. The present invention relates to a method for manufacturing an electrode assembly that can achieve these objectives.

Background Art

[0003] In recent years, the rising value of energy sources due to the depletion of fossil fuels and the increasing concern about environmental pollution have amplified the need for environmentally friendly alternative energy sources, which has become an essential and indispensable factor for future life. Therefore, research on various power generation technologies such as solar, wind, and tidal power continues, and there has also been a great deal of interest in power storage devices such as batteries for more efficiently using the electrical energy produced in this way.

[0004] Furthermore, as the technology development and demand for electronic mobile devices and electric vehicles using batteries increase, the demand for batteries as an energy source has rapidly increased. Along with this, many studies have been conducted on batteries that can meet various needs.

[0005] Rechargeable batteries have received a great deal of attention as an energy source in various product groups such as various mobile devices and electric vehicles. Such rechargeable batteries are excellent energy resources that can be used instead of conventional products using fossil fuels, do not generate by-products due to energy use, and have been in the spotlight as an environmentally friendly energy source.

[0006] A secondary battery includes an electrode assembly formed by alternately stacking electrodes and separators, and a battery case that houses such an electrode assembly. Conventionally, a variety of methods have existed for manufacturing electrode assemblies. For example, stack type, folding type, stack-and-fold type, jelly roll method, and lamination-and-stack method are widely known in the industry. Among these, the Z-folding method (or zigzag folding method), obtained by alternately arranging at least one negative electrode and at least one positive electrode on one or both sides of a rectangular separator and folding it in a zigzag direction, is a representative manufacturing method that improves the efficiency of electrode assembly production.

[0007] Figure 1 is a conceptual perspective view illustrating a conventional method for manufacturing an electrode assembly using the Z-folding method.

[0008] Referring to Figure 1, the Z-folding method involves manufacturing an electrode assembly 90 by folding a long rectangular separator 30 in a zigzag pattern, interposing a positive electrode 12 and a negative electrode 11 between them. Specifically, the separator 30 is folded once, the positive electrode 12 is placed on the folded separator 30, the separator 30 is then folded on the placed positive electrode 12, and the negative electrode 11 is placed on the folded separator 30. This process can be repeated to manufacture the electrode assembly 90. The positive electrode 12 and the negative electrode 11 each have a positive electrode tab 12-1 and a negative electrode tab 11-1 attached to them in a protruding state. Even when the separator 30 is folded, these positive electrode tabs 12-1 and negative electrode tabs 11-1 are not completely covered by the separator 30, but are stacked so that at least a portion of them protrudes outside the separator 30. In this way, once the zigzag folding is complete, the completed electrode assembly 90 can be fabricated. In Figure 1, the completed electrode assembly 90 is shown at the bottom. Looking at this electrode assembly 90, the positive electrode tab 12-1 and the negative electrode tab 11-1 are not completely covered by the separator 30, and at least a portion of them protrudes outside the separator stack. This allows for connection to external terminals and electrode leads.

[0009] However, conventional Z-folding methods can be problematic when the shape of electrodes 11 and 12 is not a simple rectangle. For example, if the electrode includes a recessed portion, and the electrode tab is located in that recess, applying the conventional Z-folding method directly presents problems. This is because, during the zigzag folding process, when the separator 30 covers the electrode, it completely covers the recessed portion of the electrode and the electrode tab located therein, making it impossible to utilize the electrode tab thereafter. Furthermore, simply cutting the separator 30 in the recessed portion to solve this problem can result in the electrode tab being cut off or damaged during the cutting process of the separator 30, thus the problem remains unresolved. [Overview of the project] [Problems that the invention aims to solve]

[0010] The present invention was derived to solve the above-mentioned problems, and the object of the present invention is to provide a method for manufacturing an electrode assembly that can improve upon the limitations of conventional electrode separator lamination technology and ensure a degree of freedom in cell design (such as the degree of freedom in tab position design).

[0011] Furthermore, the present invention provides a method for manufacturing an electrode assembly that solves the problem of separator folding during the process of manufacturing an electrode assembly by stacking electrode separators, and prevents problems such as uncut separators due to process tolerances. [Means for solving the problem]

[0012] The method for manufacturing an electrode assembly according to the present invention includes: a step of forming a pre-cut portion in which a separator is prepared and a portion of the separator is pre-cut for each unit length of the separator; a step of forming an electrode stack in which the separator that has gone through the pre-cut portion formation step is folded and an electrode stack is formed by interposing electrodes that have electrode tab connecting portions in which electrode tabs are connected between the folded separators; a main cutting step in which cutting lines connected to the pre-cut portion are formed in the electrode stack so as to cut out the separator at a position corresponding to the electrode tab connecting portion, and the separator is cut out; and a separator scrap removal step is to remove the separator scrap cut out in the main cutting step.

[0013] The electrode tab connecting portion of the electrode has a recessed shape and includes a base edge, which is the edge from which the electrode tab protrudes, and a side edge connected to the base edge. The pre-cutting portion formation process allows the separator to be pre-cut in the electrode stack state so that the pre-cutting portion forms a line shape separated by a predetermined distance from the base edge.

[0014] The predetermined distance can be smaller than the protrusion length of the electrode tab that extends from the base edge.

[0015] In the process of forming an electrode stack, the process of folding the separator is a process of folding the separator in a zigzag pattern, and the process of folding the separator in a zigzag pattern can be performed so that the separator is folded in a zigzag pattern at unit lengths.

[0016] The main cutting process may include a first cutting step of cutting the separator such that a cutting line parallel to the side is formed, while maintaining a predetermined distance from the side.

[0017] The main cutting process may include a second cutting step in which a separator is cut so as to form a cutting line that connects the cutting line formed in the first cutting step and the cutting line formed in the pre-cutting section formation step.

[0018] The second cutting step allows the separator to be cut such that the cutting line formed by the second cutting step has a curved shape.

[0019] The second cutting step allows the separator to be cut such that the cutting line formed by the second cutting step is more recessed toward the base edge than the cutting line formed by the pre-cutting section.

[0020] The first cutting step and the second cutting step can be performed in sequence.

[0021] The first cutting step and the second cutting step can be performed simultaneously.

[0022] The main cutting process can cut a separator laminate that is stacked in multiple layers in the state of an electrode laminate at once.

[0023] The formation process of the precutting portion can be performed by a laser cutting method or a die cutting method.

[0024] The main cutting process can be performed by a laser cutting method or a die cutting method.

[0025] After the main cutting process, a separator scrap removal process for removing the separator scrap cut out by the main cutting process can be further included.

Effect of the Invention

[0026] The method for manufacturing an electrode assembly according to the present invention can improve the limitations of the conventional electrode separator lamination technology and ensure the degree of freedom in cell design (such as the degree of freedom in tab position design).

[0027] In addition, the method for manufacturing an electrode assembly according to the present invention can solve the problem of folding of the separator and prevent problems such as uncutting of the separator due to process tolerances during the process of manufacturing the electrode assembly by laminating the electrode separator.

Brief Description of the Drawings

[0028] [Figure 1] It is a conceptual perspective view showing a method for manufacturing a conventional electrode assembly by a Z-folding method. [Figure 2] It is a flowchart schematically showing a method for manufacturing an electrode assembly according to an embodiment of the present invention. [Figure 3] It is a perspective view explaining the formation process of the precutting portion in the method for manufacturing an electrode assembly according to an embodiment of the present invention. [Figure 4] It is a plan view showing an electrode inserted into a separator in the method for manufacturing an electrode assembly according to an embodiment of the present invention. [Figure 5] This is a perspective view illustrating the electrode stack formation process in a method for manufacturing an electrode assembly according to one embodiment of the present invention. [Figure 6] This is a perspective view illustrating the main cutting process in a method for manufacturing an electrode assembly according to one embodiment of the present invention. [Figure 7] This is a plan view showing an enlarged view of the separator cutting line portion illustrated in Figure 6. [Figure 8] This is a perspective view illustrating the process of removing the separator task wrap in a method for manufacturing an electrode assembly according to one embodiment of the present invention. [Figure 9] This is a plan view illustrating an electrode assembly manufactured by a method for manufacturing an electrode assembly according to one embodiment of the present invention. [Figure 10] This is an enlarged view showing a magnified view of section E of the dotted box in Figure 9. [Figure 11] This is a cross-sectional view taken along line A-A' in Figure 10. [Figure 12] This is a cross-sectional view taken along line B-B' in Figure 10. [Modes for carrying out the invention]

[0029] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited or restricted by the following embodiments.

[0030] For the purpose of clearly describing the present invention, detailed descriptions of related known technologies that are irrelevant to the description or that could obscure the gist of the invention have been omitted. In this specification, when assigning reference numerals to components in each drawing, the same or similar reference numerals are used throughout the specification for components that are the same or similar.

[0031] Furthermore, the terms and words used in this specification and in the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather should be interpreted in a manner consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0032] Manufacturing method for electrode assemblies Figure 1 is a conceptual perspective view illustrating a conventional Z-folding method for manufacturing an electrode assembly. Figure 2 is a flowchart illustrating a manufacturing method for an electrode assembly according to one embodiment of the present invention. Figure 3 is a perspective view illustrating the pre-cutting process in the manufacturing method for an electrode assembly according to one embodiment of the present invention. Figure 4 is a plan view illustrating the electrode inserted into the separator in the manufacturing method for an electrode assembly according to one embodiment of the present invention. Figure 5 is a perspective view illustrating the electrode stack formation process in the manufacturing method for an electrode assembly according to one embodiment of the present invention. Figure 6 is a perspective view illustrating the main cutting process in the manufacturing method for an electrode assembly according to one embodiment of the present invention. Figure 7 is a plan view showing an enlarged view of the separator cutting line portion illustrated in Figure 6. Figure 8 is a perspective view illustrating the separator clap removal process in the manufacturing method for an electrode assembly according to one embodiment of the present invention.

[0033] Referring to Figure 2, a method for manufacturing an electrode assembly 100 according to one embodiment of the present invention can be a method for manufacturing an electrode assembly 100 formed by stacking an electrode 110 including an electrode tab connecting portion 113 and a separator 130. Here, the electrode tab connecting portion 113 may have an inwardly recessed shape. For this purpose, a method for manufacturing an electrode assembly 100 according to one embodiment of the present invention includes a pre-cutting portion formation step P1, an electrode stack formation step P2, a main cutting step P3, and a separator task wrap removal step P4.

[0034] Referring to Figure 3, the pre-cutting section formation step P1 can be a step of preparing a separator 130 and forming a pre-cutting section 131, which is a portion of the separator 130 that has been pre-cut, at intervals of the separator 130. As shown in Figure 3, a rectangular separator 130 can be prepared, and a pre-cutting section 131, which is a portion of the separator 130 that has been pre-cut, can be formed on this separator 130. This pre-cutting section formation step P1 can be carried out by forming the pre-cutting sections 131 at predetermined intervals while the long separator 130 is spread flat, or by bending or folding the separator 130 into the required shape. Alternatively, the separator 130 can be unwound using a roll, and various methods are possible.

[0035] The process P1 for forming such pre-cut sections can be carried out by a laser cutting method or a mold cutting method. The pre-cut sections 131 can be formed for each unit length of the separator, and this unit length can be the same as the interval at which the separators 130 are folded when they are folded for the subsequent manufacture of the electrode stack 99.

[0036] Referring to Figures 4 and 5, the electrode stack formation step P2 can be a step in which the separator 130 that has gone through the pre-cutting step P1 is folded in a zigzag pattern, and an electrode 110 having an electrode tab connecting section 113 in which electrode tabs are connected between the zigzag-folded separator 130 is interposed to form an electrode stack 99.

[0037] Figure 4 illustrates an electrode 110 interposed between separators 130. The electrode 110 may include a positive electrode 110-2 and a negative electrode 110-1. The electrode 110 may have an inwardly recessed shape and may include an electrode tab connecting portion 113 to which electrode tabs are connected, and in particular, an electrode tab connecting portion 113 may have a rectangular recess. This electrode tab connecting portion 113 may include a base side 114 and a side side 115.

[0038] The electrode 110 may be provided with an electrode tab located at the electrode tab connecting portion 113. In the electrode tab connecting portion 113, the base side 114 may be the side from which the electrode tab 111 protrudes. The side side 115 may be the side connected to the base side 114. The side side 115 and the base side 114 may be in contact at a predetermined angle. In this embodiment, the base side 114 and the side side 115 may be in a perpendicular contact relationship. The positive electrode 110-2 may be provided with a positive electrode tab 111-2, and the negative electrode 110-1 may be provided with a negative electrode tab 111-1.

[0039] Referring to Figure 5, the electrode stack formation step P2 can manufacture the electrode stack 99 by folding a long rectangular separator 130, which already has pre-cut portions 131 formed on it, in a zigzag pattern, with the positive electrode 110-2 and negative electrode 110-1 shown in Figure 4 interposed between them. Here, the process of folding the separator 130 in a zigzag pattern can be done so that the separator 130 is folded into the aforementioned unit length. This is to ensure that each pre-cut portion 131 matches each electrode 110.

[0040] Specifically, the separator 130 is folded once, the positive electrode 110-2 is placed on the folded separator 130, the separator 130 is folded again on the placed positive electrode 110-2, and the negative electrode 110-1 is placed on the folded separator 130. This process can be repeated to manufacture the electrode stack 99. The positive electrode 110-2 and the negative electrode 110-1 have positive electrode tabs 111-2 and negative electrode tabs 111-1 attached to them, respectively. When folding is performed on the separator 130, these positive electrode tabs 111-2 and negative electrode tabs 111-1 are first stacked while being covered by the separator 130. In this way, once the zigzag folding is complete, a finished electrode stack 99 can be formed as shown at the bottom of Figure 5.

[0041] In the electrode stack 99 formed in this manner, the pre-cut portion 131 can be in a line shape separated by a predetermined distance D from the base edge 114 (see Figure 7). Here, the predetermined distance D can be smaller than the protrusion length L of the electrode tab 111 protruding from the base edge 114. For this reason, the pre-cut portion formation step P1 performed earlier allows the separator 130 to be pre-cut so that, in the electrode stack 99 state, the pre-cut portion 131 is in a line shape separated by a predetermined distance D from the base edge 114.

[0042] More specifically, for example, the negative electrode 110-1 can be larger than the positive electrode 110-2, and the pre-cutting portion 131 can be in the form of a line separated by a predetermined distance D from the base side 114 of the electrode tab connecting portion 113 formed on the negative electrode 110-1.

[0043] Referring to Figure 6, the main cutting process P3 can be a process in which the separator 130 located in the electrode stack 99 at a position corresponding to the electrode tab connecting portion 113 is cut out by a cutting line CL connected to the pre-cutting portion 131.

[0044] Referring to Figure 8, the separate task scrap removal step P4 can be a step that removes the separate task scrap 150 (scrap) cut out by the main cutting step P3 after the main cutting step P3. After completing such a separate task scrap removal step P4, the electrode assembly 100 can be manufactured.

[0045] When manufacturing the electrode assembly 100 using the manufacturing method for the electrode assembly 100 according to one embodiment of the present invention as described above, it is possible to improve upon the limitations of conventional lamination technology and secure a degree of freedom in cell design (such as the degree of freedom in tab position design).

[0046] Specifically, conventional cell designs were not problematic when the electrode tab 111 was positioned outside the separator 130. However, if the electrode tab 111 was, for example, located in an electrode tab connecting portion 113 recessed inside the electrode 110, and the electrode tab 111 was covered by the separator 130 in the electrode stack 99, it was difficult to cut the separator 130 in such a way that the electrode tab 111 would be exposed. During the cutting process, the electrode tab would either be damaged, or cutting without damaging the electrode tab required an extremely complex and difficult operation. This became a constraint on the positional design of the electrode tab 111.

[0047] In other words, with conventional technology, if one attempts to cut the separator 130 corresponding to the electrode tab connecting portion 113 of the electrode 110 while leaving the electrode tab 111 as is, there is a possibility that the cutting line and the electrode tab will overlap, greatly increasing the risk of damaging or cutting the electrode tab 111. Therefore, it has been difficult to cut the separator 130 as is.

[0048] Alternatively, to solve this problem, one could consider pre-cutting the portion of the separator 130 corresponding to the shape of the electrode tab connecting portion 113 and then folding it. However, in the completely cut portion, the tension of the separator 130 is lost, and defects such as bending due to surrounding airflow or static electricity occur during stacking. In particular, the portion of the separator 130 corresponding to the corner K portion of the electrode 110 where the electrode tab connecting portion 113 begins can easily be bent (see Figure 8). This is problematic because it can hinder mass production and product safety. Therefore, the manufacturing method of the electrode assembly 100 according to one embodiment of the present invention can also be considered to solve the problem of folding of the separator 130.

[0049] On the other hand, referring to Figure 7, in a method for manufacturing an electrode assembly 100 according to one embodiment of the present invention, the main cutting step P3 may include a first cutting step and a second cutting step.

[0050] The first cutting step can be a step of cutting the separator 130 so that a cutting line parallel to the side edge 115 is formed, while being separated from the side edge 115 by a predetermined distance G. For convenience, the pre-cutting section 131 formed in the pre-cutting section formation step can be named the first cutting line 131. If the pre-cutting section 131 is considered the first cutting line 131, the cutting line formed in the first cutting step can be the second cutting line 132 shown in Figure 7.

[0051] The second cutting step can be a step of cutting the separator 130 so that a cutting line is formed that connects the cutting line 132 formed in the first cutting step and the cutting line 131 formed in the pre-cutting section formation step P1. That is, with reference to Figure 7, the second cutting step can be a step of cutting the separator 130 so that a third cutting line 133 is formed that connects the first cutting line 131, which is the pre-cutting section 131, and the second cutting line 132. The first and second cutting steps may be performed sequentially, or they may be performed simultaneously. Through these first and second cutting steps, the separator 130 can be cut so that the separator task wrap 150 can be completely separated from the electrode laminate 99.

[0052] In the pre-cutting section formation step P1, if the separator 130 is cut one by one, then the cutting in the main cutting step P3 (i.e., the first cutting step and the second cutting step) can be performed in a way that simultaneously cuts the separator 130 stack, which is stacked in multiple layers in the electrode stack 99 state. That is, while gripping the separator stack, in which multiple separators 130 are stacked in the stacking direction, the separator stack can be cut all at once. The specific method for cutting all at once in this way may be a laser cutting method or a mold cutting method.

[0053] Referring to Figure 7, in the main cutting step P3 according to one embodiment of the present invention, the separator 130 can be cut such that the cutting line formed by the second cutting step, i.e., the third cutting line 133, is more recessed in the direction toward the base edge 114 than the cutting line formed by the pre-cutting section (i.e., the first cutting line 131).

[0054] Referring to Figure 7, the second cutting step for forming the third cutting line 133 can be a method in which the separator is cut by moving down from the end where the second cutting line 132 ends, further down toward the base edge 114 than the pre-cutting section 131, and then moving up again so as to come into contact with the pre-cutting section 131. In this way, if the third cutting line 133 is cut in a recessed shape toward the base edge 114 than the pre-cutting section 131, the pre-cutting section 131 and the third cutting line 133 can have a stepped shape.

[0055] As illustrated in Figure 7, due to tolerances during the formation process of the pre-cutting sections 131, the alignment of the pre-cutting sections 131 may not be perfectly aligned. That is, the multiple pre-cutting sections 131 formed at various positions on the separator 130 may not align to coincide on a single line after folding due to tolerances. As illustrated in Figure 7, they may appear to be aligned on multiple lines that are slightly offset. In this case, in order for the third cutting line 133 to touch all the lines of the pre-cutting sections 131, it is necessary to cut from bottom to top, passing through all the lines of the pre-cutting sections 131. In this case, the third cutting line 133 will have a shape that is recessed towards the base side 114.

[0056] If the third cutting line 133 is not in contact with the pre-cutting section 131 in the horizontal direction (i.e., the direction in which the line of the pre-cutting section 131 extends), then there may be separator 130 layers where the third cutting line 133 does not contact the pre-cutting section 131. Therefore, cutting in such a way that the third cutting line 133 descends to a shape recessed from the pre-cutting section 131 in the direction toward the base edge 114, then rises up to contact the pre-cutting section 131, can be a necessary method for manufacturing an electrode assembly 100 of superior quality more effectively and without cutting defects. This prevents problems such as uncut separators 130 due to process tolerances.

[0057] Of course, when forming the second cutting line 132 in the first cutting step, it is possible to cut so that the second cutting line 132 passes through all the pre-cutting sections 131 at once, and to omit the second cutting step. However, in this case, the cutting must be performed so that the second cutting line 132 is relatively farther away from the side edge 115. In this case, the second cutting line 132 is formed further away from the side. That is, the length of the separator 130 protruding from the side edge 115 becomes longer. In this case, unnecessary space may be wasted in the final product electrode assembly 100.

[0058] Therefore, in the present invention, in the first cutting step, the second cutting line 132 is cut at an optimal distance (or minimum distance) away from the side edge 115, and in the second cutting step, the third cutting line 133 is cut by descending in the direction toward the base edge 114 so that it is recessed compared to the pre-cutting section 131, and then rising again, thereby preventing the aforementioned waste of space and achieving optimal space efficiency.

[0059] On the other hand, in order to ensure smooth and rapid operation, the separator 130 can be cut in the second cutting step such that the cutting line 133 formed by the second cutting step has a curved shape.

[0060] On the other hand, although this embodiment describes a case in which the electrode tab connecting portion 113 has an inwardly recessed shape, this does not mean that the shape of the electrode tab connecting portion 113 is limited to this, and other forms may also be included in the scope of the present invention. That is, if the pre-cutting portion formation process P1 can ensure a degree of freedom in cell design (such as the degree of freedom in tab position design) and improve production efficiency, the present invention can also be applied when the shape of the electrode tab connecting portion 113 is not an inwardly recessed shape.

[0061] electrode assembly Figure 9 is a plan view illustrating an electrode assembly manufactured by the electrode assembly manufacturing method according to one embodiment of the present invention. Figure 10 is an enlarged view showing a magnified view of portion E of the dotted box in Figure 9. Figure 11 is a cross-sectional view taken along line A-A' in Figure 10. Figure 12 is a cross-sectional view taken along line B-B' in Figure 10.

[0062] Another embodiment of the present invention, the electrode assembly, differs from the above-described embodiment in that it relates to an electrode assembly manufactured by the method for manufacturing an electrode assembly described in the above-described embodiment.

[0063] We will omit as much as possible the information that is common to the above-described method for manufacturing the electrode assembly, and will focus on the differences below. In other words, it is obvious that if information not described in this embodiment of the electrode assembly is necessary, it can be supplemented by referring to the above-described embodiment of the method for manufacturing the electrode assembly.

[0064] Referring to Figures 9 and 10, the electrode assembly 100 according to another embodiment of the present invention includes a separator 130 and an electrode 110, and can be in a laminated form formed by stacking the electrode 110 and the separator 130. Here, the separator 130 has a zigzag folding and stacked form, and the electrode 110 can be configured to be interposed between the separators 130. The electrode 110 can also be provided with an electrode tab connecting portion 113 to which electrode tabs are connected. The electrode 110 can also be a positive electrode 110-2 or a negative electrode 110-1. The electrode 110 can be provided with an electrode tab 111. Here, the electrode tab 111 includes a positive electrode tab 111-2 and a negative electrode tab 111-1. The positive electrode 110-2 can be provided with a positive electrode tab 111-2. The negative electrode 110-1 can be provided with a negative electrode tab 111-1. Furthermore, the electrode tab 111 can be provided on the electrode tab connecting portion 113. That is, the electrode 110 can be provided with an electrode tab 111 located on the electrode tab connecting portion 113. Also, the separator 130 may be cut to a shape corresponding to the electrode tab connecting portion 113 at a position corresponding to the electrode tab connecting portion 113. By having such a configuration, the electrode assembly 100 according to the embodiment of the present invention can improve upon the limitations of conventional lamination technology and secure a degree of freedom in cell design (such as freedom in tab position design).

[0065] In the electrode assembly 100 according to an embodiment of the present invention, the electrode 110 may be provided with an electrode tab connecting portion 113. Here, the electrode 110 may, for example, be a negative electrode 110-1.

[0066] Furthermore, the electrode tab connecting portion 113 can have a recessed shape. Specifically, such an electrode tab connecting portion 113 may include a base side 114, which is the side from which the electrode tab 111 protrudes, and a side side 115 connected to the base side 114. Also, the protrusion length L of the electrode tab 111 protruding from the base side 114 can be smaller than the recess depth H of the electrode tab connecting portion 113 measured with respect to the base side 114 (see Figure 10).

[0067] Similarly, referring to Figures 9 and 10, the separator 130 having a zigzag stacked configuration may include a first cutting line 131, a second cutting line 132, and a third cutting line 133.

[0068] The first cutting line 131 may have a line shape that is separated by a predetermined distance D from the base side 114. In a method for manufacturing an electrode assembly 100 according to one embodiment of the present invention, a pre-cutting portion 131 can be formed on the separator 130 after going through a pre-cutting portion formation step P1, and the first cutting line 131 may be a cutting line formed by such a pre-cutting portion formation step P1.

[0069] Referring to Figure 10, the predetermined distance D, which is the distance the first cutting line 131 is separated from the base edge 114, can be smaller than the protrusion length L of the electrode tab 111 protruding from the base edge 114. This may be a result of manufacturing the electrode assembly 100 in a manner in which, during the pre-cutting section formation step P1, the pre-cutting section 131 is formed in a line shape separated from the base edge 114 by a predetermined distance D, and the predetermined distance is smaller than the protrusion length of the electrode tab 111 protruding from the base edge 114.

[0070] The second cutting line 132 can be a cutting line in the shape of a line parallel to the direction in which the side edge 115 extends, while being separated from the side edge 115 by a predetermined distance G. The second cutting line 132 can be a cutting line formed by the main cutting step P3 performed in the manufacturing method of the electrode assembly 100 according to the above-described embodiment. More specifically, the second cutting line 132 can be a cutting line formed by the first cutting step of the main cutting step P3.

[0071] The third cutting line 133 can be a cutting line connecting the second cutting line 132 and the first cutting line 131. The third cutting line 133 can be formed to have a shape that is recessed in the direction toward the base edge 114 compared to the first cutting line 131. With such a shape, the first cutting line 131 and the third cutting line 133 can have a stepped shape. As described above, an electrode assembly 100 having such a configuration can prevent problems such as uncutting of the separator 130 due to process tolerances, and the second cutting line 132 can be formed at an optimal (or minimum) distance from the side edge 115, eliminating wasted space and achieving optimal space efficiency.

[0072] To ensure smooth and rapid operation, in the second cutting step of the main cutting process P3, the separator 130 can be cut such that the cutting line formed by the second cutting step has a curved shape. As a result, the third cutting line 133 can be formed to have a curved shape or the shape of a part of a circle.

[0073] Referring to Figure 11, the electrode assembly 100 according to an embodiment of the present invention can have a relatively more uniform electrode 110-separator 130 overhang value X1 along the stacking direction at the position of the first cutting line 131, based on a longitudinal cross-sectional view obtained by cutting the laminate of separators 130 along the stacking direction. Also, referring to Figure 12, at the position of the second cutting line 132, the separator 130 can have a relatively more non-uniform electrode 110-separator 130 overhang value X2 along the stacking direction. Here, the electrode 110-separator 130 overhang value X refers to the distance from the end of electrode 110 to the end of separator 130.

[0074] Specifically, Figure 11 is a cross-sectional view taken along line A-A' in Figure 10, illustrating the cross-section of the separator 130 in the stacking direction from the first cutting line 131. Figure 12 is a cross-sectional view taken along line B-B' in Figure 10, illustrating the cross-section of the separator 130 in the stacking direction from the second cutting line 132.

[0075] In Figure 11, referring to the change in the length of the separator 130, it can be seen that it has a relatively uniform length. That is, referring to Figure 11, it can be seen that at the position of the first cutting line 131, the electrode 110-separator 130 overhang value X1 does not change significantly among the multiple separators 130 placed in the stacking direction, and is relatively uniform. Here, the electrode 110-separator 130 overhang value can specifically be the negative electrode-separator overhang value. That is, it can mean the value of the distance between the end of the negative electrode 110-1 and the end of the separator 130.

[0076] When considering the electrode 110-separator 130 overhang value at the position of the first cutting line 131, the end of the separator 130 is formed by the first cutting line 131, which is formed in the pre-cutting section formation step P1. In the pre-cutting section formation step P1, the separator 130 is cut one by one at a predetermined position, so that the position of the end of the separator 130 can be fixed to be constant. Therefore, the end of the separator 130 can be formed at a substantially uniform position, except for minute tolerances. As a result, a uniform electrode 110-separator 130 overhang value X1 can be obtained at the position of the first cutting line 131.

[0077] In contrast, referring to Figure 12, it can be seen that at the position of the second cutting line 132, the electrode 110-separator 130 overhang value X2 varies among the multiple separators 130 placed in the stacking direction, and is relatively more non-uniform. Here, the electrode 110-separator 130 overhang value can specifically be the negative electrode-separator overhang value. That is, it can mean the distance between the end of the negative electrode 110-1 and the end of the separator 130.

[0078] Considering the overhang value of the electrode 110-separator 130 at the position of the second cutting line 132, the end of the separator 130 is formed by the second cutting line 132, which is formed in the main cutting process P3. In the main cutting process P3, the electrode stack 99 can be cut all at once by taking a stack of separators 130 that are stacked on top of each other. When the stack of separators 130 is cut all at once while being held, the cutting length may differ among the separators 130 stacked in the thickness direction, depending on the frictional force between the cutting tool and the separator 130, the difference in contact area between the separators, and the slip phenomenon between the separators 130. Therefore, the end of the separator 130 can be formed at a substantially non-uniform position. As a result, at the position of the second cutting line 132, the electrode 110-separator 130 can have a relatively more non-uniform overhang value X1.

[0079] Specifically, referring to Figure 12, with reference to a longitudinal cross-sectional view obtained by cutting the separator stack along the stacking direction, at the position of the second cutting line 132, the separator 130 may have an electrode 110-separator 130 overhang value that gradually decreases and then gradually increases along the stacking direction. This shape may be formed by cutting the electrode stack 99, in which multiple layers of separators 130 are stacked on top of each other, by taking one layer at a time and cutting it vertically. Also, when cutting vertically with a vertically symmetrical cutting tool, at the position of the second cutting line 132, the stacked separators 130 may have an electrode 110-separator 130 overhang value that is vertically symmetrical with respect to the separator 135 stacked at an intermediate height.

[0080] As described above, the electrode assembly 100 realized by the embodiment of the present invention can improve upon the limitations of conventional lamination technology, secure a degree of freedom in cell design (such as the degree of freedom in tab position design), solve the problem of separator folding, and prevent problems such as uncut separators due to process tolerances.

[0081] secondary battery On the other hand, in yet another embodiment of the present invention, a secondary battery can be provided. The secondary battery according to an embodiment of the present invention may include the electrode assembly 100 described above and a battery case (not shown) capable of housing the electrode assembly 100.

[0082] Such secondary batteries can improve upon the limitations of conventional lamination technology, ensuring greater freedom in cell design (such as freedom in tab position design), solving the problem of separator folding, and preventing issues such as uncut separators due to process tolerances.

[0083] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible by persons with ordinary skill in the art to which the present invention pertains, within the equivalent scope of the technical concept of the present invention and the claims described below. [Explanation of symbols]

[0084] 99 Electrode Stack 90, 100 electrode assembly 110 electrodes 11, 110-1 negative electrode 12, 110-2 positive electrode 111 Electrode Tabs 111-1 Negative electrode tab 111-2 Positive Tab 113 Electrode tab connection part 114 Base edge 115 Side 30, 130 separator 131 Pre-cutting section, first cutting line 132 Second Cutting Line 133 Third Cutting Line 135 Separators stacked at intermediate height 150 Separates Tuck P1 Formation process of the pre-cut section P2 Electrode Stack Formation Process P3 Main Cutting Process P4 Separator Strap Removal Process

Claims

1. A pre-cutting section formation step, which involves preparing a separator and forming a pre-cut section in which a portion of the separator is pre-cut for each unit length of the separator, An electrode laminate formation step involves folding the separator that has undergone the pre-cutting portion formation step, and forming an electrode laminate by interposing electrodes that have electrode tab connecting portions in which electrode tabs are connected between the folded separators, In the electrode laminate, a main cutting step is performed to cut the separator by forming a cutting line connected to the pre-cutting section so that the separator located at the position corresponding to the electrode tab connecting portion is cut out. A method for manufacturing an electrode assembly, comprising a step of removing the separate task scraps (Scraps) cut out by the main cutting step.

2. The electrode tab connecting portion of the electrode has a recessed shape and includes a base side which is the side from which the electrode tab protrudes and a side side which is connected to the base side. The process of forming the pre-cut portion is as follows: The method for manufacturing an electrode assembly according to claim 1, wherein, in the state of the electrode stack, the separator is pre-cut so that the pre-cut portion is in a line shape separated by a predetermined distance from the base edge.

3. The method for manufacturing an electrode assembly according to claim 2, wherein the predetermined distance is smaller than the protrusion length of the electrode tab protruding from the base side.

4. In the process of forming the electrode stack, The process of folding the separator is the process of folding the separator in a zigzag pattern. The process of folding the separator in a zigzag pattern is to fold the separator in a zigzag pattern so that it is folded into units of the specified length, as described in claim 1, for the method of manufacturing an electrode assembly.

5. The aforementioned main cutting process is: A method for manufacturing an electrode assembly according to claim 2, comprising a first cutting step of cutting the separator such that a cutting line parallel to the side is formed while the separator is separated from the side by a predetermined distance.

6. The aforementioned main cutting process is: A method for manufacturing an electrode assembly according to claim 5, comprising a second cutting step of cutting the separator so as to form a cutting line that connects the cutting line formed by the first cutting step and the cutting line formed by the pre-cutting section formation step.

7. The second cutting step mentioned above is: The method for manufacturing an electrode assembly according to claim 6, wherein the separator is cut such that the cutting line formed by the second cutting step has a curved shape.

8. The second cutting step mentioned above is: The method for manufacturing an electrode assembly according to claim 6, wherein the separator is cut such that the cutting line formed by the second cutting step is more recessed in the direction toward the base edge than the cutting line formed by the pre-cutting section.

9. The method for manufacturing an electrode assembly according to claim 6, wherein the first cutting step and the second cutting step are performed in order.

10. The method for manufacturing an electrode assembly according to claim 6, wherein the first cutting step and the second cutting step are performed simultaneously.

11. The aforementioned main cutting process is: The method for manufacturing an electrode assembly according to claim 1, wherein a plurality of separator stacks, which are stacked in the state of the electrode stack, are cut at once.

12. The process of forming the pre-cut portion is as follows: A method for manufacturing an electrode assembly according to claim 1, which is carried out by a laser cutting method or a mold cutting method.

13. The aforementioned main cutting process is: A method for manufacturing an electrode assembly according to claim 1, which is carried out by a laser cutting method or a mold cutting method.

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