Method of manufacturing electrode assembly and electrode assembly

Abstract

A method of manufacturing an electrode assembly according to an embodiment of the present invention comprises: preparing a cell stack in which first electrodes and second electrodes having a width larger than that of the first electrodes are alternately stacked with a separator between the first electrodes and the second electrodes; a joining portion folded toward the cell stack is formed by joining a plurality of separators protruding beyond the first electrode and the second electrode to each other.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to 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, which are hereby incorporated by reference in their entirety. Technical Field

[0003] The present invention relates to a method of manufacturing an electrode assembly of a secondary battery and the electrode assembly manufactured thereby. Background Art

[0004] In recent years, due to the depletion of fossil fuels, rising energy prices, and increased concerns about environmental pollution, the demand for environmentally friendly alternative energy is becoming an indispensable factor in future life. Therefore, research on various power generation technologies such as solar energy, wind energy, and tidal energy continues, and energy storage devices such as batteries that can more efficiently utilize the generated electricity are also attracting attention.

[0005] In addition, with the development of technology and the increase in demand for electronic mobile devices and electric vehicles using batteries, the demand for secondary batteries as energy sources is rapidly increasing. Therefore, many studies are being conducted on batteries that can meet various needs.

[0006] According to the shape of a battery case, secondary batteries are divided into cylindrical batteries and prismatic batteries in which an electrode assembly is embedded in a cylindrical or prismatic metal can, and pouch batteries in which an electrode assembly is embedded in a pouch made of an aluminum laminate sheet.

[0007] In addition, the electrode assembly can be divided into various types according to its manufacturing method. For example, the electrode assembly can be divided into: a simple stacking type in which a plurality of electrodes and separators are alternately stacked, a laminated stacking type in which unit cells laminated with electrodes and separators are stacked, a jelly roll type in which electrode sheets and separator sheets are wound together, a stacking folding type in which a separator sheet in which unit cells are stacked is folded, a Z-folding type in which a separator sheet in which a plurality of electrodes are stacked is folded in a Z shape, and the like.

[0008] In particular, the laminated stacked electrode assembly has the advantages of high quality and high manufacturing speed. However, the laminated stacked electrode assembly has no or weak adhesion between unit cells, and thus, there is a risk of misalignment between the unit cells.

[0009] Furthermore, there is a risk that the separator may fold due to external force or shrink due to heat, thereby causing a direct short circuit between the positive and negative electrodes. Summary of the invention

[0010] Technical issues

[0011] An object of the present invention to solve the above-mentioned problems is to provide an electrode assembly that prevents a short circuit between electrodes having opposite polarities by bonding between separators, and a method of manufacturing the electrode assembly.

[0012] An object of the present invention to solve the above-mentioned problems is to provide an electrode assembly that is easy to bond between separators and has high energy density, and a method of manufacturing the electrode assembly.

[0013] Technical Solution

[0014] According to an embodiment of the present invention, a method for manufacturing an electrode assembly includes: preparing a battery stack in which a first electrode and a second electrode having a width greater than that of the first electrode are alternately stacked, and a separator is provided between the first electrode and the second electrode; and forming a joint portion folded toward the battery stack by joining a plurality of separators protruding beyond the first electrode and the second electrode to each other.

[0015] In forming the joined portion, the plurality of separators may be passed between the first roller and the second roller to join the plurality of separators to each other, at least one of the first roller and the second roller being heated.

[0016] The diameter of the first roller may be smaller than the diameter of the second roller.A plurality of membranes may be engaged with each other and rolled toward the first roller.

[0017] Preparing a battery stack may include: preparing a unit cell in which the sum of the number of first electrodes and the number of second electrodes is the same as the number of separators; and stacking the unit cells. In each unit cell, the length of the separator protruding outside the second electrode is 1.25 times or more the height of the battery stack.

[0018] In the unit cell, the length of the separator protruding outside the second electrode is 1.88 times or less of the height of the battery stack.

[0019] When stacking the unit cells, one type of unit cells may be repeatedly stacked, or two types of unit cells may be stacked in a predetermined order.

[0020] The engaging portion may be provided on each of both sides of the battery stack in the width direction to extend in the full length direction of the battery stack.

[0021] An electrode assembly according to an embodiment of the present invention includes: a battery stack in which a first electrode and a second electrode having a width greater than that of the first electrode are alternately stacked, with a separator between the first electrode and the second electrode; and a joining portion folded toward the battery stack by joining a plurality of separators protruding beyond the first electrode and the second electrode to each other.

[0022] The length by which the outermost separator of the plurality of separators protrudes outside the second electrode may be 1.25 times or more the height of the battery stack.

[0023] The length by which the outermost separator protrudes beyond the second electrode may be 1.88 times or less of the height of the battery stack.

[0024] The engaging portion may be provided on each of both sides of the battery stack in the width direction to extend in the full length direction of the battery stack.

[0025] The engaging portion may not protrude outside the battery stack in the stacking direction of the battery stack.

[0026] The proximal end of the engaging portion may be disposed to correspond to a central portion in a stacking direction of the battery stack.

[0027] The separator may include: a first region overlapping with the first electrode or the second electrode in the stacking direction of the battery stack; a second region configured to constitute a joint portion; and a third region configured to connect the first region to the second region. At the separator provided on each of the two outer sides, the inclination of the third region may be steeper.

[0028] Beneficial Effects

[0029] According to the preferred embodiment of the present invention, the bonding portion provided by bonding the separators to each other can prevent the first electrode and the second electrode from being short-circuited.

[0030] Furthermore, the separator can protrude from the negative electrode long enough to easily form the joining portion, thereby preventing the joining portion from being broken or disconnected.

[0031] Furthermore, since the joining portion is folded, it is possible to prevent the overall width of the electrode assembly from being unnecessarily increased, thereby increasing the energy density of the electrode assembly.

[0032] Furthermore, since the roller can position the inner end of the engaging portion as close to the battery stack as possible, the width of the electrode assembly increased by the separator can be minimized, and the energy density of the electrode assembly can be improved.

[0033] Furthermore, effects that are obvious to those skilled in the art can be predicted from the configuration according to the embodiment of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The following drawings attached to this specification together with the detailed description of the present invention illustrate preferred embodiments and functions of the present invention to further understand the technical essence of the present invention, and thus the present invention should not be construed as being limited to the drawings.

[0035] Figure 1 is a perspective view showing an electrode assembly according to an embodiment of the present invention.

[0036] Figure 2 is a cross-sectional view showing an electrode assembly according to an embodiment of the present invention.

[0037] Figure 3 It is shown that the formation Figure 2 A cross-sectional view of the state of the bonding part.

[0038] Figure 4 is a flowchart illustrating a method of manufacturing an electrode assembly according to another embodiment of the present invention.

[0039] Figure 5 is a schematic diagram showing an apparatus for manufacturing a unit battery.

[0040] Figure 6 and Figure 7 is a view showing an example of a stacking structure of a battery stack.

[0041] Figure 8 is a schematic diagram illustrating an example of a method for manufacturing a joining portion.

[0042] Fig. 9 is a schematic diagram showing another example of the method for manufacturing a joining portion. DETAILED DESCRIPTION

[0043] Hereinafter, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the present invention. However, the present invention can be implemented in several different forms and is not limited or constrained by the following embodiments.

[0044] In order to explain the present invention clearly, the detailed description of the related known technology that is irrelevant to the description or may unnecessarily obscure the main points of the present invention is omitted, and in this specification, reference numerals are added to the elements of each drawing. In this case, the same or similar reference numerals are assigned to the same or similar elements throughout the specification.

[0045] Furthermore, the terms or words used in the specification and claims should not be strictly interpreted as ordinary meanings or meanings based on dictionaries, but should be interpreted as meanings and concepts consistent with the scope of the present invention based on the principle that the inventor can appropriately define the concepts of the terms to best describe and interpret his invention.

[0046] Figure 1 is a perspective view showing an electrode assembly according to an embodiment of the present invention, Figure 2 is a cross-sectional view showing an electrode assembly according to an embodiment of the present invention.

[0047] The electrode assembly 10 according to the embodiment of the present invention may include a battery stack 11 in which a separator 130 is provided between stacked electrodes 110 and 120 , and a joint portion 12 in which a plurality of separators 130 protruding out of the electrodes 110 and 120 are joined to each other.

[0048] Each electrode 110 and 120 may have a substantially square shape. Each electrode 110 and 120 may have a substantially square shape in the entire length direction of the battery stack 11 (e.g., Figure 1 A pair of long sides extending in a direction parallel to the Y axis in the battery stack 11 and in a full width direction of the battery stack 11 (for example, Figure 1 A pair of short sides extending in a direction parallel to the X-axis.

[0049] The electrodes 110 and 120 may include a first electrode 110 and a second electrode 120. The width of the second electrode 120 may be greater than the width of the first electrode 110. The first electrodes 110 and the second electrodes 120 are alternately stacked with a separator 130 therebetween. For example, the first electrode 110 may be a positive electrode, and the second electrode 120 may be a negative electrode.

[0050] The separator 130 may protrude outside the electrodes 110 and 120 and may be joined to each other to form a joining portion 12. The joining portion 12 may be formed by joining the edges of the separator 130 to each other. In more detail, the joining portion 12 may be formed by joining two edges in the width direction of the separator 130 to each other. Therefore, the joining portion 12 may be provided on both sides of the battery stack 11 in the width direction.

[0051] Therefore, a short circuit between the long sides of the electrodes 110 and 120 can be reliably prevented. In particular, since the full length of the electrode assembly 10 is longer than the full width (e.g., a long battery), there is a risk that the edge in the width direction of the separator 130 is folded. Therefore, if the joint portion 12 is provided on each of both sides in the width direction of the battery stack 11, the above problem can be effectively prevented.

[0052] The long engaging portion 12 may be provided in the entire length direction of the battery stack 11. However, not limited thereto, a plurality of engaging portions 12 may be provided in the entire length direction of the battery stack 11 at predetermined intervals.

[0053] The joint portion 12 may be folded toward the battery stack 11. In more detail, the joint portion 12 may be folded toward the battery stack 11 at least once. Figure 2 As shown, the engagement portion 12 may be folded once. As another example, the engagement portion 12 may be double-sided folded (DSF).

[0054] Therefore, the full width of the electrode assembly 10 can be prevented from being unnecessarily increased, so that the energy density can be increased more. In addition, when the electrode assembly 10 is accommodated in a pouch-type battery case (not shown), the interference of the joint portion 12 with the battery case can be minimized. In addition, compared with the case where the short joint portion 12 is provided so as not to be folded, the joint force between the plurality of separators forming the joint portion 12 can be strengthened.

[0055] With respect to the stacking direction of the battery stack 11, the folded joint portion 12 may not protrude outside the battery stack 11. In more detail, the entirety of the folded joint portion 12 may overlap the battery stack 11 in the full width direction of the battery stack 11. For example, when the joint portion 12 is as shown in FIG. Figure 2 When folded once as shown, the end of the engagement portion 12 may not protrude beyond the uppermost end or the lowermost end of the battery stack 11 .

[0056] Therefore, the height of the electrode assembly 10 may be prevented from being unnecessarily increased, thereby more increasing the energy density. In addition, when the electrode assembly 10 is accommodated in a pouch-type battery case (not shown), interference of the joining portion 12 with the battery case may be minimized.

[0057] 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 battery stack 11, a second region 132 forming the joint portion 12, and a third region 133 connecting the first region 131 to the second region 132. The first region 131 may be parallel to the electrodes 120 and 130. The third regions 133 of the plurality of separators 130 may be arranged to be inclined close to each other in a direction toward the outside.

[0058] All separators 130 of the battery stack 11 may be joined at once to form the joint portion 12. The proximal end of the joint portion 12 may be arranged to correspond to the battery stack 11 in the stacking direction (eg, Figure 1 Therefore, at the diaphragm 130 provided on each of the two outer sides, the inclination of the third region 133 can be steeper. The longer the diaphragm 130 provided on the two outer sides is, the longer the third region 133 can be formed.

[0059] If the proximal end of the joint portion 12 is arranged eccentrically downward relative to the stacking direction of the battery stack 11, there is a problem that the third region 133 of the uppermost separator 130 must be very long. That is, the proximal end of the joint portion 12 can be set to correspond to the central portion of the battery stack 11, so that the length of the outermost separator 130 required to form the joint portion 12 can be reduced. The outermost separator 130 can be a separator 130 disposed at the outermost side of the battery stack 11, or a separator 130 stacked in the electrodes 110 and 120 disposed at the outermost side of the battery stack 11.

[0060] Since the length of the third region 133 is set longer when the separator 130 is provided at each of the two outer sides, the length of the outermost separator 130 must be long enough to easily form the joint portion 12. In addition, as the height of the battery stack 11 increases, the length of the outermost separator 130 required to form the joint portion 12 must also increase.

[0061] Therefore, the length of the outermost separator 130 of the plurality of separators 130 of the electrode assembly 10 protruding outside the second electrode 120 may be 0.7 times or more of the height h of the battery stack 11. Therefore, the joint portion 12 may be easily formed, and the third region 133 of the outermost separator 130 may be prevented from being broken or disconnected after the joint portion 12 is formed.

[0062] In more detail, if Figure 2 As shown, when viewed in the full width direction of the battery stack 11 , the length of the outermost 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 battery stack 11 .

[0063] The length of each separator 130 protruding out of the second electrode 120 refers to the sum of the length of the bonding portion 12 of each separator 130 and the length of the third region 133 .

[0064] Figure 3 It is shown that the formation Figure 2 A cross-sectional view of the state of the bonding part.

[0065] Before forming the joint portion 12, the outermost separator 130 of the battery stack 11 is formed to have a length different from that of the other separators 130, which may be inefficient in terms of manufacturing. Figure 3 As shown, before the joining portion 12 is formed, the plurality of separators 130 provided in the battery stack 11 may have the same width or similar widths.

[0066] Before forming the joining portion 12, the length d of the separator 130 protruding from the battery stack 11 beyond the second electrode 120 may be 0.7 times or more, preferably 1.25 times or more, the height h of the battery stack 11. Therefore, the joining portion 12 can be easily formed.

[0067] In addition, before forming the joint portion 12, the length d of the separator 130 protruding from the battery stack 11 beyond the second electrode 120 may be 2.4 times or less, preferably 1.88 times or less, the height h of the battery stack 11. Therefore, the separator 130 can be prevented from being formed too long unnecessarily, and the manufacturing cost of the battery stack 11 can be reduced.

[0068] That is, before forming the joining portion 12 , the length d of the separator 130 protruding from the battery stack 11 beyond the second electrode 120 may be 0.7 to 2.4 times, preferably 1.25 to 1.88 times, the height h of the battery stack 11 .

[0069] For example, the height h of the battery stack 11 may be about 8 mm, and the length of each separator 130 protruding out of the second electrode 120 may be 10 mm to 15 mm.

[0070] The battery stack 11 may be formed by stacking a plurality of unit cells 100. That is, the battery stack 11 may be a laminated stack (L&S) type. In each unit cell 100, the sum of the number of first electrodes 110 and second electrodes 120 may be equal to the number of separators 130. For example, Figure 3 As shown, each unit cell may include one first electrode 110 , one second electrode 120 , and two separators 130 .

[0071] The electrodes 110 and 120 and the separator 130 provided in each unit cell 100 may be in a laminated state.

[0072] The adhesion between the adjacent unit cells 100 may be weaker than the adhesion between the electrodes 110 and 120 and the separator 130 within each unit cell 100. In more detail, the adhesion between each electrode 110 and 120 of one unit cell 100 and the separator 130 of another unit cell 100 may be weaker than the adhesion between each electrode 110 and 120 and the separator 130 within one unit cell 100. Based on these features, it can be determined that the battery stack 11 is a laminated stack (L&S) type, rather than a simple stack type.

[0073] 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, of the height h of the battery stack 11 in which the plurality of unit cells 100 are stacked. In addition, in each unit cell 100, the length d of the separator 130 protruding beyond the second electrode 120 of the battery stack 11 may be 2.4 times or less, preferably 1.88 times or less, of the height h of the battery stack 11.

[0074] That is, in each unit cell 100 , the length d of the separator 130 protruding from the battery stack 11 beyond the second electrode 120 may be 0.7 to 2.4 times, preferably 1.25 to 1.88 times, the height h of the battery stack 11 where the plurality of unit cells 100 are stacked.

[0075] Figure 4 is a flowchart showing a method of manufacturing an electrode assembly according to another embodiment of the present invention, Figure 5 is a schematic diagram showing an apparatus for manufacturing a unit battery, Figure 6 and Figure 7 is a view showing an example of a stacking structure of a battery stack, Figure 8 is a schematic diagram illustrating an example of a method for manufacturing a joining portion.

[0076] Hereinafter, a method for manufacturing the above-mentioned electrode assembly 10 will be described as another embodiment of the present invention.

[0077] A method of manufacturing an electrode assembly according to another embodiment of the present invention (hereinafter referred to as “manufacturing method”) includes a process of preparing a battery stack 11 ( S10 ) and a process of forming a joining portion 12 ( S20 ).

[0078] The process ( S10 ) of preparing the battery stack 11 may include a process ( S11 ) of preparing the unit cells 100 and a process ( S12 ) of stacking the unit cells 100 .

[0079] Below, we will refer to Figure 5 A process ( S11 ) of preparing the unit cell 100 is described.

[0080] The separator unwinder 230 may unwind the separator roll mounted thereon to unfold the sheet-shaped separator 1 .

[0081] The separator unwinders 230 may be provided in pairs, and the sheet-like separators 1 unwound from the pair of separator unwinders 230 may be aligned side by side to face each other.

[0082] The electrode unwinding machines 210 and 220 may unwind the electrode rolls mounted thereon to unwind the sheet-shaped electrodes 110 and 120 .

[0083] The electrode unwinding machine 230 may be provided in pairs. The sheet-shaped first electrode 110 unwound from one electrode unwinding machine 210 may be cut into the first electrode 110 having a predetermined width by the cutter 242, and may be arranged at regular intervals on one sheet-shaped separator 130. The sheet-shaped second electrode 120 unwound from another electrode unwinding machine 220 may be cut into the second electrode 120 having a predetermined width by the cutter 241, and may be arranged at regular intervals on another sheet-shaped separator 130. In this process, the second electrode 120 may be cut to be longer than the first electrode 110.

[0084] For example, the second electrodes 120 may be arranged at regular intervals between a pair of sheet-shaped separators 130, and the first electrodes 110 may be arranged at regular intervals on the upper separator 130 of the pair of sheet-shaped separators 130. However, this is not limiting, and the first and second electrodes 110 and 120 may be arranged oppositely.

[0085] In addition, Figure 5 Different from the illustration, the electrodes 110 and 120 each having a predetermined width may be manufactured in a previous process, and the previously manufactured electrodes 110 and 120 may be placed on the diaphragm 130 by a transfer device (not shown) such as a pick-and-place device.

[0086] Therefore, the electrode stack 101 in which the sheet-shaped separators 130 and the electrodes 110 and 120 having a predetermined width are alternately stacked may be formed.

[0087] The electrode stack 101 may be laminated by the laminating device 260. That is, the laminating device 260 may laminate the separator 130 and the electrodes 110 and 120 of the electrode stack 101 to each other.

[0088] For example, the laminating device 260 may include a heater to heat the electrode stack 101 and a press roller (not shown) to press the electrode stack 101. However, the configuration of the laminating device 260 is not limited thereto and may vary as desired.

[0089] The laminated electrode stack 101 may be cut into unit cells 100 by a cutter 243. In more detail, the sheet-like separator 130 of the laminated electrode stack 101 may be cut into a separator 130 having a predetermined width by a cutter 243. In this process, the separator 130 may be cut to be longer than the second electrode 120. In the unit cell 100, the length of the separator 130 protruding beyond the second electrode 120 may be 0.7 times or more and 2.4 times or less of the height of the battery stack 11 to be manufactured subsequently. Preferably, in the unit cell 100, the length of the separator 130 protruding beyond the second electrode 120 may be 1.25 times or more and 1.88 times or less of the height of the battery stack 11 to be manufactured subsequently.

[0090] Thus, it is possible to prepare the unit cell 100. However, this is just an exemplary method, and the unit cell 100 may also be prepared by other methods.

[0091] Below, we will refer to Figure 6 and Figure 7 The process ( S12 ) of stacking the unit battery 100 is described.

[0092] When the process of stacking the unit batteries 100 (S12) is performed, a plurality of unit batteries 100 may be stacked. In more detail, as shown in FIG. Figure 6 As shown, one type of unit cells 100 may be repeatedly stacked, or as Figure 7 As shown, two or more types of unit cells 100a and 100b may be stacked in a given order.

[0093] like Figure 6 As shown, when one type of unit battery 100 is repeatedly stacked, the unit battery 100 may have a four-layer structure in which electrodes 110 and 120 and separator 130 are alternately stacked. For example, the unit battery 100 may have a four-layer structure in which separator 130, second electrode 120, separator 130, and first electrode 110 are sequentially stacked.

[0094] like Figure 7As shown, when two or more types of unit batteries 100a and 100b are stacked in a given order, if two or more types of unit batteries 100a and 100b are stacked in a given order, a four-layer structure in which electrodes 110 and 120 and separators 130 are alternately stacked, or a structure in which a four-layer structure is repeatedly arranged can be formed.

[0095] For example, the first type unit cell 100a may have a six-layer structure in which the separator 130, the first electrode 110, the separator 130, the second electrode 120, the separator 130, and the first electrode 110 are sequentially stacked, and the second type unit cell 100b may have a six-layer structure in which the separator 130, the second electrode 120, the separator 130, the first electrode 110, the separator 130, and the second electrode 120 are sequentially stacked. Therefore, when the first type unit cell 100a and the second type unit cell 100b are sequentially stacked, a structure in which a four-layer structure is repeatedly arranged three times may be formed.

[0096] Thus, a plurality of unit cells 100 may be stacked to manufacture a battery stack 11 in which the first electrodes 110 and the second electrodes 120 are alternately stacked with the separators 130 .

[0097] When the battery stack 11 is formed using only the unit cells 100, the electrodes 110 and 120 may be disposed at the outermost side of the battery stack 11, and the separator 130 may be disposed at the other outermost side. However, it is not limited thereto, and by additionally stacking sub-unit cells (not shown) on a plurality of unit cells 100, the separator 130 may be disposed at both outermost sides of the battery stack 11, or the electrodes 110 and 120 may be disposed at both outermost sides of the battery stack 11. Since this is a well-known technique, a detailed description thereof will be omitted.

[0098] Below, we will refer to Figure 8 The process ( S20 ) of forming the bonding portion 12 is described.

[0099] As an example of a method of forming the bonding portion 12, Figure 8 A pair of rollers 270 are shown.

[0100] Each roller 270 may rotate around a rotation axis parallel to the full length direction of the battery stack 11. Each roller 270 may be a single long roller formed in the full length direction of the battery stack 11. However, it is not limited thereto, and each roller 270 may include a plurality of sub-heating rollers arranged at predetermined intervals in the full length direction of the battery stack 11. In this case, a plurality of engaging portions 12 may be formed at predetermined intervals in the full length direction of the battery stack 11.

[0101] In the process ( S20 ) of forming the joining portion 12 , the plurality of separators 130 may be joined to each other while passing between a pair of rollers 270 , at least one of which is heated.

[0102] In more detail, the edges of the plurality of separators 130 protruding out of the negative electrode 160 in the width direction may pass between a pair of rollers 270 and be joined to each other. At least one of the pair of rollers 270 may press the plurality of separators 130 while being heated to a temperature sufficiently higher than room temperature. Thus, the edges of the plurality of separators 130 may be joined by thermoforming to form the joining portion 12.

[0103] In this process, it is apparent that an edge fixing jig (not shown) configured to gather the plurality of separators 130 protruding out of the negative electrode 120 is used.

[0104] The pair of rollers 270 may include a first roller 271 and a second roller 282. The diameter of the first roller 271 may be smaller than the diameter of the second roller 272. Therefore, the plurality of separators 130 may be rolled toward the first roller 271 while being engaged with each other. That is, while the engagement portion 12 is formed, the engagement portion 12 may be folded toward the battery stack 11.

[0105] In order to conveniently fold the joint portion 12, the rotation speed of each roller 271 and 272 and the movement path of the rotation axis of each roller 271 and 272 may be appropriately set. For example, the second roller 272 may rotate and move along the outer circumference of the first roller 271. Therefore, there is an advantage that a separate process is not required to fold the joint portion 12.

[0106] In addition, the first roller 271 and the second roller 272 may be rotated and moved toward the battery stack 11. Therefore, the inner end of the joint portion 12 may be formed to be as close to the battery stack 11 as possible. The inner end of the joint portion 12 may represent the second region 132 of the separator 130 (see Figure 2 ) and a boundary between the third region 133. Therefore, an increase in the width of the electrode assembly 10 caused by the third region 133 of the separator 132 may be minimized, and the energy density of the electrode assembly 10 may be improved.

[0107] If the folded joint portion 12 protrudes outside the battery stack 11 in the stacking direction of the battery stack 11 , a part of the end side of the joint portion 12 may be cut.

[0108] Fig. 9 is a schematic diagram showing another example of the method for manufacturing a joining portion.

[0109] As another example of a method of forming the bonding portion 12, a method such as Fig. 9 A pair of rollers 270 are shown having the same or similar diameters.

[0110] The plurality of separators 130 , more specifically, edges of the plurality of separators 130 protruding out of the negative electrode 160 in the width direction may pass between a pair of rollers 270 and be engaged with each other.

[0111] In more detail, a pair of rollers 270 may move toward the battery stack 11 with the edges of the gathered separators 130 located between the pair of rollers 270. Here, it is apparent that a fixing jig (not shown) configured to gather the edges of the plurality of separators 130 protruding out of the negative electrode 160 is used.

[0112] Each roller 270 is rotatable about a rotation axis parallel to the full length direction of the battery stack 11. Each roller 270 is rotatable and movable in the full width direction of the battery stack 11.

[0113] As described above, the pair of rollers 270 may be moved toward the battery stack 11 to join the plurality of separators 130 to each other, and thus the inner end of the joining portion 12 may be formed as close as possible to the battery stack 11. Therefore, the increase in the width of the electrode assembly 10 caused by the third region 133 of the separator 132 may be minimized, and the energy density of the electrode assembly 10 may be improved. Thereafter, a process of folding the joining portion 12 toward the battery stack 11 may be additionally performed.

[0114] The above-disclosed subject matter is illustrative and not restrictive, and the appended claims are intended to cover all such modifications, variations, and other embodiments that fall within the true spirit and scope of the present invention.

[0115] Therefore, the embodiments of the present invention are illustrative rather than restrictive, and the technical spirit of the present invention is not limited to the above-mentioned embodiments.

[0116] Therefore, the scope of the invention is defined not by the detailed description of the invention but by the appended claims, and all differences within the scope will be construed as being included in the present invention.

[0117] [Explanation of Reference Numerals]

[0118] 10: Electrode assembly

[0119] 11: Battery stack

[0120] 12: Jointing part

[0121] 100: Cell

[0122] 110: First electrode

[0123] 120: Second electrode

[0124] 130: Diaphragm

[0125] 131: First Area

[0126] 132: Second Area

[0127] 133: The Third Area

[0128] 270: Roller

[0129] 271: First Roll

[0130] 272: Second Roller

Claims

1. A method for manufacturing an electrode assembly, the method comprising: preparing a battery stack in which a first electrode and a second electrode having a width greater than that of the first electrode are alternately stacked, and a separator is provided between the first electrode and the second electrode; and By joining a plurality of separators protruding out of the first electrode and the second electrode to each other, a joined portion folded toward the battery stack is formed.

2. The method according to claim 1, wherein: In forming the joining portion, the plurality of separators pass between a first roller and a second roller, at least one of which is heated, and are joined to each other.

3. The method according to claim 2, wherein: The diameter of the first roller is smaller than the diameter of the second roller, The plurality of separators are engaged with each other and rolled toward the first roller.

4. The method according to claim 1, wherein: Preparing the battery 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; stacking the unit cells, In each of the unit cells, a length of the separator protruding out of the second electrode is 1.25 times or more of a height of the battery stack.

5. The method according to claim 4, wherein: In the unit cell, a length of the separator protruding out of the second electrode is 1.88 times or less of a height of the battery stack.

6. The method according to claim 4, wherein: When stacking the unit cells, One type of unit cell is repeatedly stacked, or Two types of unit cells are stacked in a predetermined order.

7. The method according to claim 1, wherein: The engaging portion is provided on each of both sides of the battery stack in the width direction to extend in the full length direction of the battery stack.

8. An electrode assembly, comprising: A battery stack, in which first electrodes and second electrodes having a width greater than that of the first electrodes are alternately stacked, with a separator between the first electrodes and the second electrodes; and A joint portion is folded toward the battery stack by mutually joining a plurality of separators protruding out of the first electrode and the second electrode.

9. The electrode assembly according to claim 8, wherein: A length by which an outermost separator of the plurality of separators protrudes outside the second electrode is 1.25 times or more the height of the battery stack.

10. The electrode assembly according to claim 9, wherein: The length of the outermost separator protruding outside the second electrode is 1.88 times or less of the height of the battery stack.

11. The electrode assembly according to claim 8, wherein: The engaging portion is provided on each of both sides of the battery stack in the width direction to extend in the full length direction of the battery stack.

12. The electrode assembly according to claim 8, wherein: The engaging portion does not protrude outside the battery stack in the stacking direction of the battery stack.

13. The electrode assembly according to claim 8, wherein: The proximal end of the engaging portion is disposed to correspond to a central portion in a stacking direction of the battery stack.

14. The electrode assembly according to claim 8, wherein: The diaphragm comprises: a first region overlapping the first electrode or the second electrode in a stacking direction of the battery stack; a second region configured to constitute the engagement portion; and a third area configured to connect the first area to the second area, Therein, at the diaphragm arranged on each of the two outer sides, the inclination of the third region is steeper.

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