Electrode assembly manufacturing method 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 contents disclosed in the documents of said 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 technology]

[0003] In recent years, with the depletion of fossil fuels causing rising energy prices and increasing concerns about environmental pollution, the demand for environmentally friendly alternative energy sources has become an essential factor for future life. Therefore, research into various electricity production technologies such as solar, wind, and tidal power has continued, and there has also been great interest in power storage devices such as batteries to more efficiently use the electrical energy produced in this way.

[0004] Furthermore, with the increasing technological development and demand for battery-based electronic mobile devices and electric vehicles, the demand for secondary batteries as energy sources is rapidly increasing, and as a result, much research is being conducted on secondary batteries that can meet various demands.

[0005] Depending on the shape of the battery case, secondary batteries can be classified into cylindrical batteries and prismatic batteries in which the electrode assembly is housed in a cylindrical or prismatic metal can, and pouch batteries in which the electrode assembly is housed in a pouch-shaped case made of an aluminum laminate sheet.

[0006] In addition, electrode assemblies can be classified into various types depending on their manufacturing method, such as a simple stack type in which multiple electrodes and separators are alternately stacked, a lamination & stack type in which unit cells, each of which is made up of an electrode and a separator laminated together, a jelly-roll type in which an electrode sheet and a separator sheet are rolled up together, a stack & folding type in which a separator sheet on which unit cells are stacked is folded, and a z-folding type in which a separator sheet on which multiple electrodes are stacked is folded in a zigzag pattern.

[0007] In particular, the lamination and stack type electrode assembly has the advantage of being high quality and being able to be manufactured quickly. However, the lamination and stack type electrode assembly has a risk of misalignment between the unit cells due to the lack or weak adhesion between the unit cells. Furthermore, the separator may be bent by an external force or may shrink due to heat, which may cause a direct short circuit between the positive electrode and the negative electrode. Summary of the Invention [Problem to be solved by the invention]

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide an electrode assembly and a manufacturing method thereof that prevents short circuits between electrodes having opposite polarities by bonding separators together. Another object of the present invention is to provide an electrode assembly in which separators can be easily bonded and which has a high energy density, and a manufacturing method thereof. [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 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 electrodes and the second electrodes to each other to form a joint that is folded toward the cell stack.

[0010] During the forming of the joint, the plurality of separators may 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 may be wound around the first roll while being joined together.

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

[0012] In the step of stacking 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 joints may be located on both sides of the cell stack in the width direction and extend along the entire length of the cell stack.

[0013] An electrode assembly according to an embodiment of the present invention may include 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 a joint portion in which a plurality of the separators protruding outward from the first electrodes and the second electrodes are joined to each other and folded toward the cell stack.

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

[0015] The joints may be located on both sides of the cell stack in the width direction and extend along the entire length of the cell stack. The folded joint portion may not protrude beyond the cell stack in the stacking direction of the cell stack. The base end of the joint may be located so as to correspond to the center of the cell stack in the stacking direction.

[0016] The separator may include a first region overlapping the first electrode or the second electrode in the stacking direction of the cell stack, a second region forming the joint, and a third region connecting the first region and the second region. The outermost separators may have a steeper gradient in the third region. [Effects of the Invention]

[0017] According to a preferred embodiment of the present invention, the joint formed by joining the separators together can prevent short circuits from occurring between the first electrode and the second electrode. Furthermore, the separator protrudes sufficiently far beyond the negative electrode, making it possible to easily form the joint, and preventing the joint from being broken or disconnected. In addition, since the joints can be folded, the overall width of the electrode assembly can be prevented from becoming unnecessarily large, and the energy density of the electrode assembly can be increased.

[0018] In addition, the inner end of the joint can be formed as close as possible to the cell stack by the rolling, which minimizes the increase in width of the electrode assembly due to the separator, thereby improving the energy density of the electrode assembly. In addition, the present invention can include effects that can be easily predicted by a person skilled in the art from the configurations according to the preferred embodiments of the present invention. [Brief explanation of the drawings]

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

[0020] [Figure 1] 1 is a perspective view of an electrode assembly according to an embodiment of the present invention; [Figure 2] 1 is a cross-sectional view of an electrode assembly according to an embodiment of the present invention. [Figure 3] FIG. 3 is a cross-sectional view showing the state before the bonded portion shown in FIG. 2 is formed. [Figure 4] 10 is a flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present invention. [Figure 5] FIG. 2 is a schematic diagram of a unit cell manufacturing apparatus. [Figure 6] 1A to 1C are diagrams showing various examples of stacking structures of a cell stack; [Figure 7] 1A to 1C are diagrams showing various examples of stacking structures of a cell stack; [Figure 8] 1A to 1C are schematic diagrams illustrating an example of a method for manufacturing a joint. [Figure 9] 10A to 10C are schematic diagrams showing another example of a method for manufacturing a joint. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will now be described in detail with reference to the accompanying drawings, so that those skilled in the art can easily understand and practice the preferred embodiments of the present invention. However, the present invention may be embodied in various different forms and is not limited to the following embodiments.

[0022] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may unnecessarily obscure the gist of the present invention will be omitted, and in this specification, when assigning reference symbols to components in each drawing, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0023] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, based on the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0024] FIG. 1 is a perspective view of an electrode assembly according to one embodiment of the present invention, and FIG. 2 is a cross-sectional view of the 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 stack 11 in which electrodes 110, 120 are stacked with separators 130 interposed therebetween, and a joint 12 in which a plurality of separators 130 protruding outward from the electrodes 110, 120 are joined to each other.

[0025] Each electrode 110, 120 may have a substantially rectangular shape and may have a pair of long sides extending along the entire length of the cell stack 11 (e.g., parallel to the Y axis in FIG. 1 ) and a pair of short sides extending along the entire width of the cell stack 11 (e.g., parallel to the X axis in FIG. 1 ).

[0026] The electrodes 110, 120 may include a first electrode 110 and a second electrode 120. The second electrode 120 may have a width greater than that of the first electrode 110. The first electrode 110 and the second electrode 120 may be alternately stacked with a separator 130 interposed therebetween. 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 may protrude outward beyond the electrodes 110, 120 and may be joined to each other to form a joint 12. The joint 12 may be formed by joining edges of the separator 130 to each other. More specifically, the joint 12 may be formed by joining both widthwise edges of the separator 130 to each other. Therefore, the joint 12 may be located on both widthwise sides of the cell stack 11.

[0028] This reliably prevents short circuits between the long sides of the electrodes 110, 120. In particular, the longer the overall length of the electrode assembly 10 is compared to the overall width (e.g., a long cell), the greater the risk of bending the widthwise edges of the separator 130. Therefore, positioning the joints 12 on both sides of the cell stack 11 in the width direction is effective in preventing this concern.

[0029] The joints 12 may be formed long in the overall length direction of the cell stack 11. However, this is not limited thereto, and multiple joints 12 may be formed at predetermined intervals in the overall length direction of the cell stack 11.

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

[0031] This prevents the overall width of the electrode assembly 10 from becoming unnecessarily large, thereby increasing the energy density. Also, 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. Also, the bonding strength between the multiple separators 130 forming the joint 12 can be stronger than when the joint 12 is formed too short to be folded.

[0032] The folded joint 12 may not protrude beyond the cell stack 11 in the stacking direction of the cell stack 11. More specifically, the entire folded joint 12 may overlap the cell stack 11 in the entire width direction of the cell stack 11. For example, as shown in FIG. 2, when the joint 12 is folded once, the end of the joint 12 may not 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, thereby increasing the 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 overlapping the first electrode 110 or the second electrode 120 in the stacking direction of the cell stack 11, a second region 132 forming the joint 12, and a third region 133 connecting 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 the plurality of separators 130 may be formed to be inclined in a direction approaching each other as they go outward.

[0035] All separators 130 of the cell stack 11 may be joined at once to form the joint 12. The base end of the joint 12 may be located to correspond to the center of the stacking direction of the cell stack 11 (e.g., a direction parallel to the Z axis in FIG. 1). Therefore, the gradient of the third region 133 may be steeper in the separators 130 located on both outer sides. The length of the third region 133 may be longer in the separators 130 located on both outer sides.

[0036] If the base end of the joint 12 were positioned eccentrically downward relative to the stacking direction of the cell stack 11, there would be a problem in that the third region 133 of the uppermost separator 130 would have to be very long. In other words, by positioning the base end of the joint 12 so that it corresponds to the center 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 positioned outermost in the cell stack 11, or it may be a separator 130 on which the electrodes 110, 120 positioned outermost in the cell stack 11 are stacked.

[0037] The separators 130 located on both sides have longer third regions 133, so the outermost separators 130 must be sufficiently long to easily form the joints 12. As the height of the cell stack 11 increases, the length of the outermost separators 130 required to form the joints 12 must also increase.

[0038] Therefore, the length by which the outermost separator 130 of the multiple separators 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 makes it possible to easily form the joint 12 and to prevent fracture or disconnection of the third region 133 of the outermost separator 130 after the joint 12 is formed.

[0039] More specifically, when viewed in the overall width direction of the cell stack 11 as shown in Figure 2, the length by 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 refer to the sum of the length of the joint portion 12 and the length of the third region 133 of each separator 130 .

[0040] FIG. 3 is a cross-sectional view showing the state before the bonded portion shown in FIG. 2 is formed. It would be inefficient in terms of manufacturing to form the outermost separator 130 of the cell stack 11 to have a different length from the other separators 130 before forming the joints 12. Therefore, as shown in FIG. 3, the multiple separators 130 included in the cell stack 11 before forming the joints 12 may have the same or similar widths.

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

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

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

[0044] Meanwhile, the cell stack 11 may be formed by stacking a plurality of unit cells 100. That is, the cell stack 11 may be a lamination and stack (L&S) type. In each unit cell 100, the total number of first electrodes 110 and second electrodes 120 may be the same as the number of separators 130. For example, as shown in FIG. 3, each unit cell may include one first electrode 110, one second electrode 120, and two separators 130.

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

[0046] Therefore, in each unit cell 100, the length (d) by which the 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 formed by stacking a plurality of unit cells 100. Also, in each unit cell 100, the length (d) by which the separator 130 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 stack 11.

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

[0048] FIG. 4 is a flowchart of a method for manufacturing an electrode assembly according to another embodiment of the present invention, FIG. 5 is a schematic diagram of a unit cell manufacturing apparatus, FIGS. 6 and 7 are diagrams showing various examples of stacking structures of cell stacks, and FIG. 8 is a schematic diagram showing an example of a method for manufacturing a joint.

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

[0050] The step (S10) of preparing the cell stack 11 may include a step (S11) of preparing the unit cells 100 and a step (S12) of stacking the unit cells 100. Hereinafter, the step (S11) of preparing the unit cell 100 will be described with reference to FIG.

[0051] The separator unwinder 230 can unwind the separator roll attached thereto and unwind the sheet-shaped 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 in parallel and facing each other.

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

[0053] For example, the second electrodes 120 may be disposed at regular intervals between a pair of sheet-like separators 130, and the first electrodes 110 may be disposed at regular intervals on the upper separator 130 of the pair of sheet-like separators 130. However, the present invention is not limited thereto, and the first electrodes 110 and the second electrodes 120 may be disposed in reverse.

[0054] Also, unlike what is shown in FIG. 5, it is of course possible for electrodes 110, 120 having a predetermined width to already be manufactured in a previous process, and for the already manufactured electrodes 110, 120 to be placed on the separator 130 by a transfer device (not shown) such as a pick-and-place device. As a result, an electrode stack 101 can be formed in which sheet-like separators 130 and electrodes 110 and 120 having a predetermined width are alternately stacked.

[0055] The electrode stack 101 can be laminated by a laminator 260. That is, the laminator 260 can laminate the separator 130 and the electrodes 110, 120 of the electrode stack 101 together.

[0056] For example, the laminating device 260 may include a heater that heats the electrode stack 101 and a pressure roller (not shown) that presses the electrode stack 101. However, the configuration of the laminating device 260 is not limited to this and may vary as necessary.

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

[0058] The step of stacking the unit cells 100 (S12) will be described below with reference to FIGS. In the stacking step (S12) of the unit cells 100, a plurality of unit cells 100 may be stacked. More specifically, as shown in Fig. 6, one type of unit cell 100 may be repeatedly stacked, or as shown in Fig. 7, two or more types of unit cells 100a, 100b may be stacked in a predetermined order.

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

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

[0061] For example, the 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 sequentially stacked, and the 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 sequentially stacked. Therefore, when one first type unit cell 100a and one second type unit cell 100b are stacked, a structure in which the above four-layer structure is repeated three times can be formed. Therefore, by stacking a plurality of unit cells 100, a cell stack 11 can be manufactured in which first electrodes 110 and second electrodes 120 are alternately stacked with separators 130 interposed therebetween.

[0062] When the cell stack 11 is formed only from unit cells 100, electrodes 110 and 120 may be disposed on one outermost side of the cell stack 11, and a separator 130 may be disposed on the other outermost side. However, without being limited thereto, it is of course possible to further stack sub-unit cells (not shown) on a plurality of unit cells 100, so that separators 130 or electrodes 110 and 120 are disposed on both outermost sides of the cell stack 11. This is a well-known technique, so a detailed description thereof will be omitted.

[0063] Hereinafter, the step (S20) of forming the bonded portion 12 will be described with reference to FIG. One example of a method for forming the joint 12 is to use a pair of rolls 270 as shown in FIG.

[0064] Each roll 270 can rotate around a rotation axis parallel to the overall length of the cell stack 11. Each roll 270 may be a single roll formed to be long in the overall length of the cell stack 11. However, without being limited thereto, each roll 270 may include a plurality of sub-heating rolls arranged at predetermined intervals in the overall length of the cell stack 11. In this case, a plurality of bonding portions 12 may be formed at predetermined intervals in the overall length of the cell stack 11.

[0065] In the step (S20) of forming the joint 12, the separators 130 may be joined to one another 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 bonded to one another while passing between a pair of rolls 270. At least one of the pair of rolls 270 can pressurize the multiple separators 130 while being heated to a temperature sufficiently higher than room temperature. This allows the edges of the multiple separators 130 to be bonded by hot forming, forming the bonded portion 12. It is apparent that in this process, a fixing jig (not shown) configured to gather together the edges of the plurality of separators 130 that protrude beyond the negative electrode 120 can be used.

[0066] The 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. Therefore, the multiple separators 130 can be wound onto the first roll 271 side while being joined to each other. That is, the separators 130 can be folded toward the cell stack 11 at the same time that the joints 12 are formed.

[0067] To facilitate folding of the joint 12, the rotation speed of each of the rolls 271 and 272 and the movement path of the rotation shaft of each of the rolls 271 and 272 can be appropriately set. For example, the second roll 272 can move along the outer periphery of the first roll 271 while rotating. This has the advantage that a separate process for folding the joint 12 is not required.

[0068] In addition, the first roll 271 and the second roll 272 can move toward the cell stack 11 while rotating. 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 FIG. 2) and the third region 133 of the separator 130. This can minimize an 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. If the folded joint 12 protrudes beyond the cell stack 11 in the stacking direction of the cell stack 11, it is possible to cut off a part of the end side of the joint 12.

[0069] FIG. 9 is a schematic diagram showing 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 of the same or similar diameter, as shown in FIG.

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

[0071] More specifically, a pair of rolls 270 can move toward the cell stack 11 while sandwiching the edges of the gathered separators 130. At this time, it is clear that a fixing jig (not shown) configured to gather the edges of the plurality of separators 130 that protrude beyond the negative electrodes 120 can be used.

[0072] Each roll 270 can rotate around a rotation axis parallel to the overall length of the cell stack 11. Each roll 270 can move in the overall width direction of the cell stack 11 while rotating. In this manner, the pair of rolls 270 moves toward the cell stack 11 to bond the plurality of separators 130, so that the inner end of the bonding portion 12 can be formed as close as possible to the cell stack 11. This minimizes an 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. Thereafter, a process of folding the bonding portion 12 toward the cell stack 11 can be further performed.

[0073] The above description is merely an illustrative example of the technical concept of the present invention, and various modifications and variations can be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0074] Therefore, the embodiments disclosed in the present invention are intended to explain rather than limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0075] The scope of protection of the present invention should be interpreted by the claims below, and all technical ideas within the equivalent range thereof should be interpreted as being included in the scope of the present 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. preparing a cell stack in which first electrodes and second electrodes having a width greater than that of the first electrodes are alternately stacked with separators interposed therebetween; a step of joining the separators that protrude outward beyond the first electrode and the second electrode to each other and forming a joint portion that is folded toward the cell stack; A method for manufacturing an electrode assembly, comprising:

2. During the step of forming the joint, The method of manufacturing an electrode assembly according to claim 1 , wherein the plurality of separators are bonded to each other while passing between a first roll and a second roll, at least one of which is heated.

3. The diameter of the first roll is smaller than the diameter of the second roll, The method for manufacturing an electrode assembly according to claim 2 , wherein the plurality of separators are wound around the first roll while being joined to one another.

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

5. The method of manufacturing an electrode assembly according to claim 4 , wherein the length by which the separator protrudes beyond the second electrode in the unit cell is 1.88 times or less the height of the cell stack.

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

7. The method for manufacturing an electrode assembly according to claim 1 , wherein the joints are located on both sides of the cell stack in a width direction and extend in a full length direction of the cell stack.

8. a cell stack in which first electrodes and second electrodes having a width greater than that of the first electrodes are alternately stacked with separators interposed therebetween; a joint portion where a plurality of the separators protruding outward beyond the first electrode and the second electrode are joined to each other and folded toward the cell stack; An electrode assembly comprising:

9. The electrode assembly of claim 8 , wherein a length by which an outermost separator of the plurality of separators protrudes beyond the second electrode is 1.25 times or more the height of the cell stack.

10. The electrode assembly according to claim 9 , wherein the length by which the outermost separator protrudes beyond the second electrode is 1.88 times or less the height of the cell stack.

11. The electrode assembly according to claim 8 , wherein the joints are located on both sides of the cell stack in a width direction and extend along the entire length of the cell stack.

12. The electrode assembly according to claim 8 , wherein the folded joint portion does not protrude beyond the cell stack in the stacking direction of the cell stack.

13. The electrode assembly according to claim 8 , wherein a base end of the joint is located so as to correspond to a center portion of the cell stack in a stacking direction.

14. The separator is a first region overlapping the first electrode or the second electrode in a stacking direction of the cell stack; a second region that forms the joint; a third region connecting the first region and the second region, The electrode assembly according to claim 8 , wherein the third region has a steeper gradient in the separators located on both sides.

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