Method for manufacturing an electrode assembly and electrode assembly

Abstract

A method for manufacturing an electrode assembly according to an embodiment of the present invention may include the steps of preparing a cell stack in which first electrodes and second electrodes having a width wider than the first electrodes are alternately stacked with separators interposed therebetween, and joining a plurality of the separators that protrude outward from the first and second electrodes to each other to form a joint that is folded toward the cell stack.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0108707 filed on August 29, 2022 and Korean Patent Application No. 10-2023-0109253 filed on August 21, 2023, and all the contents disclosed in the documents of the Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a method for manufacturing an electrode assembly for a secondary battery and an electrode assembly manufactured thereby.

Background Art

[0003] In recent years, as the price of energy sources has increased due to the depletion of fossil fuels and interest in environmental pollution has grown, the demand for environmentally friendly alternative energy sources has become an essential and indispensable factor for future life. Therefore, research on various power generation technologies such as solar power, wind power, and tidal power has continued, 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 technology development and demand for electronic mobile devices and electric vehicles using batteries have increased, the demand for secondary batteries as an energy source has rapidly increased, and thus, many studies on secondary batteries that can meet various requirements have been conducted.

[0005] Secondary batteries can be classified into cylindrical batteries and prismatic batteries in which the electrode assembly is built into a cylindrical or prismatic metal can according to the shape of the battery case, and pouch-type batteries in which the electrode assembly is built into a pouch-shaped case of an aluminum laminate sheet, etc.

[0006] Furthermore, electrode assemblies can be classified into various types depending on their manufacturing method. For example, electrode assemblies can be classified into simple stack type, in which multiple electrodes and separators are stacked alternately; lamination and stack type, in which unit cells with laminated electrodes and separators are stacked; jelly-roll type, in which the electrode sheet and separator sheet are wound together; stack and folding type, in which a separator sheet with stacked unit cells is folded; and z-folding type, in which a separator sheet with multiple electrodes stacked is folded in a zigzag pattern.

[0007] Lamination and stack type electrode assemblies, in particular, have the advantages of high quality and rapid manufacturing. However, because the adhesive force between unit cells in lamination and stack type electrode assemblies is weak or nonexistent, there is a risk of misalignment between unit cells. Furthermore, the separator may be bent by external force or contract due to heat, potentially causing a direct short circuit between the positive and negative electrodes. [Overview of the project] [Problems that the invention aims to solve]

[0008] One problem that the present invention aims to solve is to provide an electrode assembly and a method for manufacturing the same that prevents short circuits between electrodes having opposite polarities by joining separators. Another problem that the present invention aims to solve is to provide an electrode assembly and a method for manufacturing the same, which allows for easy joining of separators and has a high energy density. [Means for solving the problem]

[0009] A method for manufacturing an electrode assembly according to an embodiment of the present invention may include the steps of: preparing a cell laminate in which a first electrode and a second electrode having a wider width than the first electrode are alternately stacked with separators in between; and joining a plurality of separators that protrude outward from the first electrode and the second electrode to each other to form a joint that is folded toward the cell laminate.

[0010] During the step of forming the joint, the plurality of separators can be joined to one another while passing between a first roll and a second roll, at least one of which is heated. The diameter of the first roll may be smaller than the diameter of the second roll. The plurality of separators can be wound onto the first roll side while being joined together.

[0011] The step of preparing the cell stack may include the step of preparing unit cells in which the sum of the number of the first electrodes and the second electrodes is equal to the number of separators, and the step of stacking the unit cells. In the unit cell, the length to which the separator protrudes beyond the second electrode may be 1.25 times or more the height of the cell stack. In the aforementioned unit cell, the length to which the separator protrudes beyond the second electrode may be 1.88 times or less the height of the cell stack.

[0012] During the stacking step of the unit cells, one type of unit cell may be repeatedly stacked, or two or more types of unit cells may be stacked in a predetermined order. The joint portion is located on both sides in the width direction of the cell laminate and can extend in the overall length direction of the cell laminate.

[0013] An electrode assembly according to an embodiment of the present invention may include a cell laminate in which a first electrode and a second electrode having a wider width than the first electrode are alternately stacked with separators in between, and a joint portion in which a plurality of separators protruding outward from the first and second electrodes are joined to each other and folded toward the cell laminate.

[0014] The length to which the outermost separator among the plurality of separators protrudes beyond the second electrode may be 1.25 times or more the height of the cell stack. The length to which the outermost separator protrudes beyond the second electrode may be 1.88 times or less the height of the cell stack.

[0015] The joint portion is located on both sides in the width direction of the cell laminate and can extend in the overall length direction of the cell laminate. The folded joint portion does not need to protrude beyond the cell laminate with respect to the stacking direction of the cell laminate. The base end of the joint can be positioned so as to correspond to the central part with respect to the stacking direction of the cell laminate.

[0016] The separator may include a first region that overlaps with the first or second electrode in the stacking direction of the cell stack, a second region that forms the joint, and a third region that connects the first and second regions. The further outward the separator is located, the steeper the gradient of the third region can be. [Effects of the Invention]

[0017] According to a preferred embodiment of the present invention, a joint formed by joining separators together can prevent a short circuit from occurring between the first electrode and the second electrode. Furthermore, the separator protrudes sufficiently longer than the negative electrode, allowing the joint to be easily formed and preventing breakage or disconnection of the joint. Furthermore, because the joint can be folded, it prevents the overall width of the electrode assembly from becoming unnecessarily large, and allows for a higher energy density of the electrode assembly.

[0018] In addition, since the inner end of the joint can be formed as close as possible to the cell laminate by the roll, the increase in the width of the electrode assembly due to the separator can be minimized, and the energy density of the electrode assembly can be improved. In addition, effects that can be easily predicted by those skilled in the art from the configurations according to the preferred embodiments of the present invention can be included.

Brief Description of the Drawings

[0019] The following drawings attached to this specification illustrate the preferred embodiments of the present invention and serve to further understand the technical idea of the present invention together with the detailed description of the invention to be described later. Therefore, the present invention should not be construed as being limited only to the matters described in the drawings.

[0020] [Figure 1] It is a perspective view of an electrode assembly according to an embodiment of the present invention. [Figure 2] It is a cross-sectional view of an electrode assembly according to an embodiment of the present invention. [Figure 3] It is a cross-sectional view showing the state before the joint shown in FIG. 2 is formed. [Figure 4] It is a flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present invention. [Figure 5] It is a schematic diagram of a unit cell manufacturing apparatus. [Figure 6] It is a diagram showing various examples of the laminated structure of the cell laminate. [Figure 7] It is a diagram showing various examples of the laminated structure of the cell laminate. [Figure 8] It is a schematic diagram showing an example of a method for manufacturing a joint. [Figure 9] It is a schematic diagram showing another example of a method for manufacturing a joint.

Modes for Carrying Out the Invention

[0021] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying 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 may be realized in various different forms and is not limited or restricted by the following embodiments.

[0022] To clearly explain the present invention, detailed descriptions of relevant prior art that are irrelevant to the description or that may unnecessarily obscure the essence 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 assigned to components that are the same or similar throughout the specification.

[0023] 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 appropriately define the concepts of terms in order to best describe their invention.

[0024] Figure 1 is a perspective view of an electrode assembly according to one embodiment of the present invention, and Figure 2 is a cross-sectional view of an electrode assembly according to one embodiment of the present invention. An electrode assembly 10 according to one embodiment of the present invention may include a cell laminate 11 in which electrodes 110 and 120 are stacked with separators 130 interposed between them, and a joint portion 12 in which a plurality of separators 130 that protrude outward from the electrodes 110 and 120 are joined to each other.

[0025] Each electrode 110, 120 can have a substantially square shape. Each electrode 110, 120 can have a pair of long sides extending in the overall direction of the cell stack 11 (for example, in the direction parallel to the Y-axis in Figure 1) and a pair of short sides extending in the overall width direction of the cell stack 11 (for example, in the direction parallel to the X-axis in Figure 1).

[0026] The electrodes 110 and 120 may include a first electrode 110 and a second electrode 120. The second electrode 120 may have a wider width than the first electrode 110. The first electrode 110 and the second electrode 120 may be stacked alternately with a separator 130 in between. For example, the first electrode 110 may be a positive electrode and the second electrode 120 may be a negative electrode.

[0027] The separator 130 can protrude outward from the electrodes 110 and 120 and can be joined to each other to form a joint 12. The joint 12 can be formed by joining the edges of the separator 130 to each other. More specifically, the joint 12 can be formed by joining the two widthwise edges of the separator 130 to each other. Therefore, the joint 12 can be located on both sides in the widthwise direction of the cell stack 11.

[0028] This reliably prevents short circuits between the long sides of electrodes 110 and 120. In particular, the longer the total length of the electrode assembly 10 is compared to its total width (for example, a long cell), the greater the risk of the widthwise edges of the separator 130 being bent. Therefore, having the joint 12 located on both sides of the widthwise side of the cell stack 11 is effective in preventing the above-mentioned concerns.

[0029] The joint portion 12 can be formed to be long in the overall length direction of the cell laminate 11. However, it is not limited to this, and multiple joint portions 12 can be formed at predetermined intervals in the overall length direction of the cell laminate 11.

[0030] The joint 12 can be folded toward the cell stack 11. More specifically, the joint 12 can be folded toward the cell stack 11 at least once. As an example, the joint 12 can be folded once, as shown in Figure 2. As another example, the joint 12 can be double-sided folded (DSF).

[0031] This prevents the overall width of the electrode assembly 10 from becoming unnecessarily large, and allows for higher energy density. Furthermore, when the electrode assembly 10 is housed in a pouch-type battery case (not shown), interference between the joint 12 and the battery case can be minimized. Additionally, compared to the case where the joint 12 is formed to be too short to be folded, the bonding force between the multiple separators 130 forming the joint 12 can be increased.

[0032] The folded joint 12 does not need to protrude beyond the cell stack 11 in the stacking direction of the cell stack 11. More specifically, the entire folded joint 12 can overlap with the cell stack 11 in the full width direction of the cell stack 11. For example, as shown in Figure 2, when the joint 12 is folded once, the end of the joint 12 does not need to protrude beyond the top or bottom end of the cell stack 11.

[0033] This prevents the height of the electrode assembly 10 from becoming unnecessarily large, and allows for higher energy density. Furthermore, when the electrode assembly 10 is housed in a pouch-type battery case (not shown), interference between the joint 12 and the battery case can be minimized.

[0034] Each separator 130 may include a first region 131 that overlaps with the first electrode 110 or the second electrode 120 in the stacking direction of the cell stack 11, a second region 132 that forms a joint 12, and a third region 133 that connects the first region 131 and the second region 132. The first region 131 may be parallel to the electrodes 110 and 120. The third regions 133 of multiple separators 130 may be formed inclined so that they move closer to each other as they extend outwards.

[0035] All separators 130 of the cell stack 11 can be joined at once to form a joint 12. The base end of the joint 12 can be positioned to correspond to the center with respect to the stacking direction of the cell stack 11 (for example, the direction parallel to the Z-axis in Figure 1). Therefore, the further outward the separators 130 are, the steeper the slope of the third region 133 can be. The further outward the separators 130 are, the longer the length of the third region 133 can be formed.

[0036] If the base end of the joint 12 is positioned eccentrically downward with respect to the stacking direction of the cell stack 11, there is a problem that the third region 133 of the uppermost separator 130 must become very long. That is, by positioning the base end of the joint 12 to correspond to the central part of the cell stack 11, the length of the outermost separator 130 required to form the joint 12 can be reduced. The outermost separator 130 may be the separator 130 located on the outermost side of the cell stack 11, or it may be the separator 130 on which electrodes 110 and 120 located on the outermost side of the cell stack 11 are stacked.

[0037] The further outward the separator 130 is located, the longer the length of the third region 133 becomes. Therefore, in order to easily form the joint 12, the length of the outermost separator 130 needs to be sufficiently long. Furthermore, as the height of the cell laminate 11 increases, the length of the outermost separator 130 required for forming the joint 12 must also increase.

[0038] Therefore, the length to which the outermost separator 130 of the electrode assembly 10 protrudes beyond the second electrode 120 may be 0.7 times or more the height (h) of the cell stack 11. This allows the joint 12 to be easily formed and prevents breakage or disconnection of the third region 133 of the outermost separator 130 after the joint 12 is formed.

[0039] More specifically, as shown in Figure 2, when viewed in the overall width direction of the cell stack 11, the length to which the outermost separator 130 protrudes beyond the second electrode 120 may be 0.7 times or more, preferably 1.25 times or more, the height (h) of the cell stack 11. The length by which each separator 130 protrudes beyond the second electrode 120 may mean the sum of the length of the junction 12 and the length of the third region 133 of each separator 130.

[0040] Figure 3 is a cross-sectional view showing the state before the joint shown in Figure 2 is formed. It is inefficient from a manufacturing standpoint to form the outermost separator 130 of the cell laminate 11 with a different length from the other separators 130 before the formation of the joint 12. Therefore, as shown in Figure 3, the multiple separators 130 included in the cell laminate 11 before the formation of the joint 12 can have the same or similar widths to one another.

[0041] Before the formation of the joint 12, the length (d) of the separator 130 in the cell laminate 11 that protrudes beyond the second electrode 120 may be 0.7 times or more the height (h) of the cell laminate 11, and preferably 1.25 times or more. This allows the joint 12 to be easily formed.

[0042] Furthermore, before the formation of the joint 12, the length (d) of the separator 130 in the cell laminate 11 that protrudes beyond the second electrode 120 may be 2.4 times or less, preferably 1.88 times or less, the height (h) of the cell laminate 11. This prevents the separator 130 from being formed to be unnecessarily long, and can reduce the manufacturing cost of the cell laminate 11.

[0043] In other words, before the formation of the joint 12, the length (d) of the separator 130 in the cell laminate 11 that protrudes beyond the second electrode 120 may be 0.7 to 2.4 times the height (h) of the cell laminate 11, and preferably 1.25 to 1.88 times. For example, the height (h) of the cell stack 11 may be about 8 mm, and the length by which each separator 130 protrudes beyond the second electrode 120 may be 10 mm to 15 mm.

[0044] On the other hand, the cell stack 11 can be formed by stacking multiple unit cells 100. That is, the cell stack 11 may be of the Lamination and Stack (L&S) type. Each unit cell 100 may have a total number of first electrodes 110 and second electrodes 120 equal to the number of separators 130. For example, as shown in Figure 3, each unit cell may include one first electrode 110, one second electrode 120, and two separators 130.

[0045] The electrodes 110, 120 and separator 130 contained in each unit cell 100 may be laminated to each other. The adhesive force between adjacent unit cells 100 may be weaker than the adhesive force between the electrodes 110 and 120 within each unit cell 100 and the separator 130. More specifically, the adhesive force between the electrodes 110 and 120 of one unit cell 100 and the separator 130 of the other unit cell 100 may be weaker than the adhesive force between the electrodes 110 and 120 within each unit cell 100 and the separator 130. Based on these characteristics, it can be determined that the cell laminate 11 is not a simple laminate type, but a Lamination and Stack (L&S) type.

[0046] Therefore, in each unit cell 100, the length (d) of the separator 130 protruding beyond the second electrode 120 may be 0.7 times or more, preferably 1.25 times or more, the height (h) of the cell stack 11 formed by stacking multiple unit cells 100. Alternatively, in each unit cell 100, the length (d) of the separator 130 protruding beyond the second electrode 120 may be 2.4 times or less, preferably 1.88 times or less, the height (h) of the cell stack 11.

[0047] In other words, in each unit cell 100, the length (d) of the separator 130 protruding beyond the second electrode 120 may be 0.7 to 2.4 times the height (h) of the cell stack 11 formed by stacking multiple unit cells 100, and preferably 1.25 to 1.88 times.

[0048] Figure 4 is a flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present invention, Figure 5 is a schematic diagram of a unit cell manufacturing apparatus, Figures 6 and 7 show various examples of the laminated structure of the cell laminate, and Figure 8 is a schematic diagram showing an example of a method for manufacturing a joint.

[0049] The method for manufacturing the electrode assembly 10 described above will be explained below as another embodiment of the present invention. A method for manufacturing an electrode assembly according to another embodiment of the present invention (hereinafter referred to as "manufacturing method") may include the steps of preparing a cell laminate 11 (S10) and forming a joint 12 (S20).

[0050] The step of preparing the cell stack 11 (S10) may include the step of preparing the unit cells 100 (S11) and the step of stacking the unit cells 100 (S12). The following describes the step (S11) of preparing unit cell 100, referring to Figure 5.

[0051] The separator unwinder 230 can unwind the separator roll attached to it and unwind the sheet-like separator 1. The separator unwinders 230 can be provided in pairs, and the sheet-like separators 1 unwound from the pair of separator unwinders 230 can be aligned parallel to each other so as to face each other.

[0052] The electrode unwinders 210 and 220 can unwind the electrode rolls attached to them, thereby unwinding the sheet-like electrodes 110 and 120. The electrode unwinders 230 can be provided in pairs. The sheet-like first electrode 110 unwound from one electrode unwinder 210 can be cut into first electrodes 110 of a predetermined width by a cutter 242 and arranged at regular intervals on one sheet-like separator 130. The sheet-like second electrode 120 unwound from the other electrode unwinder 220 can be cut into second electrodes 120 of a predetermined width by a cutter 241 and arranged at regular intervals on the other sheet-like separator 130. In this process, the second electrodes 120 can be cut to be longer than the first electrodes 110.

[0053] For example, the second electrode 120 can be placed at regular intervals between a pair of sheet-like separators 130, and the first electrode 110 can be placed at regular intervals on the upper separator 130 of the pair of sheet-like separators 130. However, it is not limited to this, and of course, the first electrode 110 and the second electrode 120 can be placed in reverse order.

[0054] Furthermore, unlike the one shown in Figure 5, electrodes 110 and 120 having a predetermined width are already manufactured in a previous process, and the already manufactured electrodes 110 and 120 can be placed on the separator 130 by a transfer device (not shown), such as a pick-and-place device. This makes it possible to form an electrode laminate 101 in which a sheet-like separator 130 and electrodes 110 and 120 having a predetermined width are alternately stacked.

[0055] The electrode laminate 101 can be laminated by the laminating device 260. That is, the laminating device 260 can laminate the separator 130 and electrodes 110 and 120 of the electrode laminate 101 to each other.

[0056] For example, the laminating apparatus 260 may include a heater for heating the electrode laminate 101 and a pressure roller (not shown) for pressurizing the electrode laminate 101. However, the configuration of the laminating apparatus 260 is not limited thereto and may vary as needed.

[0057] The laminated electrode stack 101 can be cut into unit cells 100 by a cutter 243. More specifically, the sheet-like separator 130 of the laminated electrode stack 101 can be cut into separators 130 having a predetermined width by the cutter 243. In this process, the separator 130 can be cut to be longer than the second electrode 120. The length of the separator 130 in the unit cell 100 that protrudes beyond the second electrode 120 may be 0.7 times or more the height of the cell stack 11 that is subsequently manufactured, and may be 2.4 times or less. Preferably, the length of the separator 130 in the unit cell 100 that protrudes beyond the second electrode 120 may be 1.25 times or more the height of the cell stack 11 that is subsequently manufactured, and may be 1.88 times or less. This allows for the preparation of unit cell 100. However, this is merely an illustrative method, and unit cell 100 can also be prepared by other methods.

[0058] The step of stacking the unit cells 100 (S12) will be described below with reference to Figures 6 and 7. During the stacking step (S12) of the unit cell 100, multiple unit cells 100 can be stacked. More specifically, as shown in Figure 6, one type of unit cell 100 can be repeatedly stacked, or as shown in Figure 7, two or more types of unit cells 100a and 100b can be stacked in a predetermined order.

[0059] As shown in Figure 6, when one type of unit cell 100 is repeatedly stacked, the unit cell 100 can have a four-layer structure in which electrodes 110, 120 and separators 130 are stacked alternately. For example, the unit cell 100 can have a four-layer structure in which separators 130, second electrodes 120, separators 130, and first electrodes 110 are stacked sequentially.

[0060] As shown in Figure 7, when two or more types of unit cells 100a and 100b are stacked in a predetermined order, stacking one of each type of unit cell 100a and 100b in a predetermined order can form a four-layer structure in which electrodes 110 and 120 and separators 130 are stacked alternately, or a structure in which the above four-layer structure is repeatedly arranged.

[0061] For example, a first-type unit cell 100a may have a six-layer structure in which a separator 130, a first electrode 110, a separator 130, a second electrode 120, a separator 130, and a first electrode 110 are stacked sequentially, and a second-type unit cell 100b may have a six-layer structure in which a separator 130, a second electrode 120, a separator 130, a first electrode 110, a separator 130, and a second electrode 120 are stacked sequentially. Therefore, when one first-type unit cell 100a and one second-type unit cell 100b are stacked, a structure can be formed in which the above four-layer structure is repeated three times. Therefore, by stacking multiple unit cells 100, a cell stack 11 can be manufactured in which the first electrode 110 and the second electrode 120 are stacked alternately with a separator 130 in between.

[0062] When a cell stack 11 is formed using only unit cells 100, electrodes 110 and 120 can be placed on one outermost side of the cell stack 11, and a separator 130 can be placed on the other outermost side. However, it is not limited to this, and it is also possible to further stack sub-unit cells (not shown) on multiple unit cells 100, so that separators 130 or electrodes 110 and 120 are placed on both outermost sides of the cell stack 11. This is a well-known technique, so a detailed explanation will be omitted.

[0063] The following describes the step (S20) of forming the joint 12, with reference to Figure 8. As an example of a method for forming the joint 12, a pair of rolls 270 can be used, as shown in Figure 8.

[0064] Each roll 270 can rotate around a rotation axis parallel to the overall length direction of the cell stack 11. Each roll 270 may be a single roll formed to be long in the overall length direction of the cell stack 11. However, it is not limited to this, and each roll 270 may include a plurality of sub-heating rolls arranged at predetermined intervals in the overall length direction of the cell stack 11. In this case, multiple joints 12 can be formed at predetermined intervals in the overall length direction of the cell stack 11.

[0065] During the joint formation step (S20), the multiple separators 130 can be joined to each other while passing between a pair of rolls 270, at least one of which is heated. More specifically, the edges of the multiple separators 130 that protrude in the width direction beyond the negative electrode 120 can be joined to each other as they pass between a pair of rolls 270. At least one of the pair of rolls 270 can be heated to a temperature sufficiently higher than room temperature and pressurized to pressurize the multiple separators 130. This allows the edges of the multiple separators 130 to be joined by hot forming to form a joint 12. In this process, it is clear that a fixing jig (not shown) can be used, which is configured to bring together the edges of multiple separators 130 that protrude beyond the negative electrode 120.

[0066] A pair of rolls 270 may include a first roll 271 and a second roll 272. The diameter of the first roll 271 may be smaller than the diameter of the second roll 272. Thus, multiple separators 130 can be wound towards the first roll 271 while being joined to each other. That is, the joint 12 can be formed and at the same time be folded toward the cell laminate 11.

[0067] To facilitate the folding of the joint 12, the rotational speed of each roll 271, 272 and the movement path of the rotation axis of each roll 271, 272 can be appropriately set. For example, the second roll 272 can rotate and move along the outer circumference of the first roll 271. This has the advantage of eliminating the need for a separate process to fold the joint 12.

[0068] Furthermore, the first roll 271 and the second roll 272 can rotate and move toward the cell stack 11. Therefore, the inner end of the joint 12 can be formed as close as possible to the cell stack 11. The inner end of the joint 12 may refer to the boundary between the second region 132 (see Figure 2) and the third region 133 of the separator 130. This minimizes the increase in the width of the electrode assembly 10 due to the third region 133 of the separator 130, and improves the energy density of the electrode assembly 10. If the folded joint portion 12 protrudes beyond the cell laminate 11 in the stacking direction of the cell laminate 11, it is also possible to cut off a portion of the end of the joint portion 12.

[0069] Figure 9 is a schematic diagram illustrating another example of a method for manufacturing a joint. Another example of a method for forming the joint 12 is to use a pair of rolls 270 having the same or similar diameters, as shown in Figure 9.

[0070] Multiple separators 130, more specifically, the edges of multiple separators 130 that protrude in the width direction beyond the negative electrode 120, can be joined to each other while passing between a pair of rolls 270.

[0071] More specifically, a pair of rolls 270 can move toward the cell laminate 11 side, sandwiching the edges of the separators 130 that are joined together. In this case, it is clear that a fixing jig (not shown) can be used, which is configured to bring together the edges of the multiple separators 130 that protrude beyond the negative electrode 120.

[0072] Each roll 270 can rotate around a rotation axis parallel to the overall length direction of the cell stack 11. Each roll 270 can move in the overall width direction of the cell stack 11 while rotating. In this way, as a pair of rolls 270 move toward the cell stack 11 and join multiple separators 130, the inner end of the joint 12 can be formed as close as possible to the cell stack 11. This minimizes the increase in the width of the electrode assembly 10 due to the third region 133 of the separator 130, thereby improving the energy density of the electrode assembly 10. Subsequently, a further step can be performed to fold the joint 12 toward the cell stack 11.

[0073] The above description is merely illustrative of the technical concept of the present invention, and any person with ordinary skill in the art to which the present invention belongs can make various modifications and alterations without departing from the essential characteristics of the present invention.

[0074] Therefore, the embodiments disclosed in this invention are for illustrative purposes only and not to limit the technical concept of the invention, and the scope of the technical concept of the invention is not limited by such embodiments.

[0075] The scope of protection of this invention must be interpreted in accordance with the claims described below, and all technical concepts within an equivalent scope should be interpreted as being included within the scope of rights of this invention. [Explanation of Symbols]

[0076] 10: Electrode assembly 11: Cell stack 12:Joint part 100: Unit cell 110: 1st electrode 120: 2nd electrode 130: Separator 131:First area 132:Second area 133: Third area 270: Roll 271: First Roll 272: Second Roll

Claims

1. The steps include: preparing a cell laminate in which a first electrode and a second electrode having a wider width than the first electrode are alternately stacked with a separator in between; The process includes the step of joining together a plurality of separators that protrude outward from the first electrode and the second electrode, thereby forming a joint that is folded toward the cell laminate, During the step of forming the joint, The plurality of separators are joined to each other while passing between a first roll and a second roll, at least one of which is heated. The diameter of the first roll is smaller than the diameter of the second roll. A method for manufacturing an electrode assembly, wherein the plurality of separators are joined together and wound onto the first roll.

2. The step of preparing the cell stack is: The steps include: preparing a unit cell in which the sum of the number of the first electrode and the second electrode is the same as the number of separators; The step of stacking the aforementioned unit cells is included, The method for manufacturing an electrode assembly according to claim 1, wherein in the unit cell, the length to which the separator protrudes beyond the second electrode is 1.25 times or more the height of the cell stack.

3. The method for manufacturing an electrode assembly according to claim 2, wherein in the unit cell, the length by which the separator protrudes beyond the second electrode is 1.88 times or less the height of the cell stack.

4. During the stacking step of the aforementioned unit cell, One type of unit cell is repeatedly stacked, or A method for manufacturing an electrode assembly according to claim 2, wherein two or more unit cells are stacked in a predetermined order.

5. The method for manufacturing an electrode assembly according to any one of claims 1 to 4, wherein the joint portion is located on both sides in the width direction of the cell laminate and extends in the overall length direction of the cell laminate.

6. A cell laminate in which a first electrode and a second electrode having a wider width than the first electrode are alternately stacked with a separator in between, A plurality of separators protruding outward from the first electrode and the second electrode are joined to each other, and the joint portion is folded toward the cell laminate, An electrode assembly in which the length to which the outermost separator of the plurality of separators protrudes beyond the second electrode is 1.25 times or more the height of the cell stack.

7. The electrode assembly according to claim 6, wherein the length to which the outermost separator protrudes beyond the second electrode is 1.88 times or less the height of the cell stack.

8. The electrode assembly according to claim 6, wherein the joint portion is located on both sides in the width direction of the cell laminate and extends in the overall length direction of the cell laminate.

9. The electrode assembly according to claim 6, wherein the folded joint portion does not protrude beyond the cell laminate with respect to the stacking direction of the cell laminate.

10. The electrode assembly according to claim 6, wherein the base end of the joint is positioned so as to correspond to the central part with respect to the stacking direction of the cell laminate.

11. The aforementioned separator is, A first region overlapping with the first electrode or the second electrode in the stacking direction of the cell stack, The second region forming the joint, A third region connecting the first region and the second region, The electrode assembly according to any one of claims 6 to 10, wherein the gradient of the third region becomes steeper the further outward the separator is located on both sides.

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