Method for manufacturing electrode assembly and electrochemical device including the electrode assembly

Abstract

Disclosed is a method for manufacturing an electrode assembly, comprising at least one step selected from the following: passing a heat-treated first separator and an electrode between a pair of surface-patterned rollers to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated; and passing a second separator with the preliminary electrode assembly disposed thereon between a pair of surface-patterned rollers to be pressed, and then winding the separator so that the second separator can be interposed between the preliminary electrode assemblies. Also disclosed is an electrochemical device including the electrode assembly.

Description

Technical Field

[0001] The present disclosure relates to a method for manufacturing an electrode assembly and an electrochemical device including the electrode assembly. Specifically, the present disclosure relates to a method for manufacturing an electrode assembly having improved electrolyte wetting and gas permeability characteristics, and an electrochemical device including the electrode assembly and having improved battery performance.

[0002] This application claims priority from Korean Patent Application No. 10-2020-0135061 filed in Korea on October 19, 2020, the disclosure of which is incorporated herein by reference. Background Art

[0003] Recently, interest in energy storage technology has been increasing. As its application has expanded to include energy sources for cell phones, camcorders, and notebook computers, and even electric vehicles, electrochemical devices are increasingly being researched and developed. Against this backdrop, electrochemical devices are attracting the most attention. In particular, with the recent trend toward miniaturization and lightweighting of electronic devices, the development of secondary batteries, which are compact, lightweight, and high-capacity rechargeable batteries, has become a focus.

[0004] In addition, secondary batteries can be classified according to the structure of the electrode assembly including the positive electrode, the separator and the negative electrode. Generally, the electrode assembly is divided into: a jelly roll (wound) type electrode assembly formed by winding the positive electrode and the negative electrode with a separator interposed between long sheets of positive and negative electrodes; and a stacked (laminated) type electrode assembly formed by continuously stacking the positive and negative electrodes with a separator interposed between a plurality of positive and negative electrodes cut into units of predetermined sizes.

[0005] However, such an electrode assembly according to the related art has many problems.

[0006] First, a jelly roll type electrode assembly is obtained by winding long sheets of positive and negative electrodes in a compact state to form a cylindrical or elliptical structure when viewed from a cross section. As a result, the stress caused by the expansion and contraction of the electrodes accumulates inside the electrode assembly. When this stress accumulation exceeds a certain limit, the electrode assembly deforms. This deformation of the electrode assembly causes the spacing between the electrodes to become uneven, thereby causing rapid deterioration of battery performance and adversely affecting battery safety due to internal short circuits. In addition, although long sheets of positive and negative electrodes should be wound, it is difficult to quickly wind the positive and negative electrodes while maintaining a constant spacing between the positive and negative electrodes, resulting in a decrease in productivity.

[0007] Secondly, the stacked electrode assembly requires continuous stacking of multiple positive and negative electrodes. Therefore, a separate step of transferring the electrode plates used to form a unit body is required, and the continuous stacking process requires a lot of time and labor, resulting in low productivity.

[0008] To address these issues, a stacked-folding type electrode assembly has been developed. This is an electrode assembly with an advanced structure that combines a jelly roll and a stacked structure. The stacked-folding type electrode assembly is obtained by stacking a predetermined number of positive and negative electrodes with a separator interposed between the two electrodes to form a bi-cell or full-cell, and then winding the bi-cell or full-cell using a continuous separator sheet having a long length.

[0009] When manufacturing this stacked-folding type electrode assembly, conventional lamination technology is used to bond the entire interface between the electrode and the separator under high-temperature pressing. To do this, the temperature and pressure are controlled to achieve a specific level of adhesion, and physical impact is applied to the electrode and separator.

[0010] The high-temperature pressing increases the venting time of the separator, so the resistance increases, which adversely affects the battery performance, and reduces the dielectric breakdown voltage of the separator, leading to safety issues.

[0011] Furthermore, due to the interfacial adhesion between the electrode and the separator, electrolyte wetting characteristics deteriorate, which undesirably affects output characteristics. Summary of the Invention

[0012] Technical issues

[0013] The present disclosure is designed to solve the problems of the related art, and therefore, the present disclosure aims to provide a method of manufacturing an electrode assembly that improves problems caused by interfacial adhesion between an electrode and a separator, and an electrochemical device including the electrode assembly.

[0014] Technical Solution

[0015] In one aspect of the present disclosure, a method of manufacturing an electrode assembly and an electrochemical device including the electrode assembly according to the following embodiments are provided.

[0016] According to a first embodiment, there is provided a method for manufacturing an electrode assembly, comprising the following steps:

[0017] heat-treating a plurality of electrodes and a first separator interposed between the electrodes;

[0018] Passing the heat-treated first separator and the electrode between a pair of surface-patterned rollers to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated;

[0019] disposing a plurality of the preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; and

[0020] The winding is performed in such a manner that the second separator is interposed between the preliminary electrode assemblies.

[0021] According to a second embodiment, there is provided a method for manufacturing an electrode assembly, comprising the following steps:

[0022] heat-treating a plurality of electrodes and a first separator interposed between the electrodes;

[0023] Passing the heat-treated first separator and the electrode between a pair of rollers having unpatterned surfaces and pressing them, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated;

[0024] disposing a plurality of the preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; and

[0025] The second separator having the preliminary electrode assembly disposed thereon is pressed by passing between a pair of rollers having patterned surfaces, and then wound in such a manner that the second separator is interposed between the preliminary electrode assemblies.

[0026] According to a third embodiment of the present disclosure, there is provided a method for manufacturing an electrode assembly, comprising the following steps:

[0027] heat-treating a plurality of electrodes and a first separator interposed between the electrodes;

[0028] Passing the heat-treated first separator and the electrode between a pair of surface-patterned rollers to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated;

[0029] disposing a plurality of the preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; and

[0030] The second separator having the preliminary electrode assembly disposed thereon is pressed by passing between a pair of rollers having patterned surfaces, and then wound in such a manner that the second separator is interposed between the preliminary electrode assemblies.

[0031] According to a fourth embodiment, in the method of manufacturing an electrode assembly according to any one of the first to third embodiments, the surface-patterned roller is formed by engraving a pattern on a roller surface or by attaching a pattern sheet to the roller surface.

[0032] According to a fifth embodiment, in the method for manufacturing an electrode assembly according to any one of the first to third embodiments, the pattern formed on the surface-patterned roller includes a hexagonal pattern, a quadrilateral pattern, a triangular pattern, a circular pattern, a pentagonal pattern, a straight line pattern, a diagonal line pattern, a polygonal pattern, or a combination of two or more of the above patterns.

[0033] According to a sixth embodiment, in the method of manufacturing an electrode assembly according to any one of the first to third embodiments, an area of the pattern directly facing the electrode formed on the surface-patterned roller is 1% to 99% based on the total surface area of the surface-patterned roller.

[0034] According to a seventh embodiment, there is provided an electrode assembly obtained by the method according to any one of the first to third embodiments.

[0035] According to an eighth embodiment, there is provided an electrochemical device including the electrode assembly according to the seventh embodiment accommodated in a case.

[0036] According to a ninth embodiment, in the electrochemical device according to the eighth embodiment, the electrochemical device is a lithium secondary battery.

[0037] Beneficial effects

[0038] According to an embodiment of the present disclosure, when a surface-patterned pressing roller is used during the step of pressing (laminating) electrodes and diaphragms, the contact area directly facing the electrodes, etc. during pressing can be reduced, so that the lamination load can be reduced, and thus bonding can be performed with minimized stimulation.

[0039] As a result, the problem caused by the interfacial adhesion between the electrode and the separator is solved by combining conventional lamination technology with patterning technology. Therefore, an electrode assembly with improved electrolyte wetting and gas permeability characteristics, and an electrochemical device with improved battery performance can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The accompanying drawings illustrate preferred embodiments of the present disclosure and, together with the foregoing disclosure, are used to provide a further understanding of the technical features of the present disclosure; thus, the present disclosure is not to be construed as being limited to these drawings.

[0041] Figure 1 is a schematic diagram illustrating a surface-patterned roller according to an embodiment of the present disclosure.

[0042] Figures 2 to 4 Illustrated are patterns engraved directly on the surface of the roller in various shapes.

[0043] Figure 5 A process for preparing a preliminary electrode assembly in which a first separator is laminated with a plurality of electrodes according to an embodiment of the present disclosure is illustrated.

[0044] Figure 6a A conventional press roller is illustrated.

[0045] Figure 6b Illustrated is a process of preparing a preliminary electrode assembly by using a conventional press roller.

[0046] Figure 7 Illustrated is a preliminary electrode assembly obtained by using a pair of surface-patterned rollers according to an embodiment of the present disclosure.

[0047] Figure 8 Illustrated is a preliminary electrode assembly obtained by using a conventional unpatterned roller.

[0048] Figure 9 and Figure 10 The diagram illustrates a process of passing the second separator having the preliminary electrode assembly provided thereon between a pair of rollers having patterned surfaces and being pressed.

[0049] Figure 11 is a schematic cross-sectional view illustrating one embodiment of an electrode assembly according to the related art.

[0050] Figure 12 is a schematic cross-sectional view illustrating another embodiment of an electrode assembly according to the related art.

[0051] Figure 13 is a schematic cross-sectional view illustrating still another embodiment of an electrode assembly according to the related art.

[0052] Figure 14 is a schematic cross-sectional view illustrating a structure of a stacked-folding type electrode assembly provided with single cells according to the related art.

[0053] Figure 15 is a schematic cross-sectional view illustrating a structure of a stacked-folding type electrode assembly provided with dual batteries according to the related art. DETAILED DESCRIPTION

[0054] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Before the description, it should be understood that the terms used in the specification and the appended claims should not be interpreted as limited to the general meaning and dictionary meaning, but should be interpreted based on the principle of allowing the inventor to appropriately define the terms for the best interpretation, on the basis of the meaning and concept corresponding to the technical aspects of the present disclosure.

[0055] The present disclosure aims to address problems encountered in methods of manufacturing stacked-folding electrode assemblies according to related art, and relates to an improved method of manufacturing an electrode assembly. In particular, the present disclosure relates to an improved method of manufacturing a stacked-folding electrode assembly, and an electrochemical device including an electrode assembly obtained by the method.

[0056] Hereinafter, a method of manufacturing a stack-folding type electrode assembly according to the related art will be explained.

[0057] Figures 11 to 13 1 is a schematic cross-sectional view illustrating the structure of a stack-folding type electrode assembly. In the drawings, the same reference numerals denote the same components.

[0058] Reference Figures 11 to 13 The electrode assembly 10, 20, 30 includes a plurality of unit cells 7a, 7b, 7c1, 7c2, each of which includes: a first separator 3a, 3b, 3c; and a negative electrode 1a, 1b, 1c and a positive electrode 5a, 5b, 5c disposed on both sides of the first separator 3a, 3b, 3c. The positive electrode 5a, 5b, 5c includes a positive electrode active material layer formed on both surfaces of the positive electrode current collector, and the negative electrode 1a, 1b, 1c includes a negative electrode active material layer formed on both surfaces of the negative electrode current collector. Figures 11 to 13 As shown in , the unit cell may include unit cells having various structures, such as full cells 7a and 7b in which a positive electrode 5a and 5b and a negative electrode 1a and 1b are provided on both sides of a first separator 3a and 3b; and bicells 7c1 and 7c2 in which a first separator 3c is provided on each of both surfaces of a positive electrode 5c or a negative electrode 1c and a negative electrode 1c or a positive electrode 5c is provided on the first separator 3c (positive electrode / separator / negative electrode / separator / positive electrode structure or negative electrode / separator / positive electrode / separator / negative electrode structure). In addition, the positive electrode / separator / negative electrode / separator / positive electrode structure 7c1 or the negative electrode / separator / positive electrode / separator / negative electrode structure 7c2 may be collectively referred to as a bicell, and the positive electrode / separator / negative electrode structure 7a and 7b may be collectively referred to as a single cell.

[0059] In the electrode assemblies 10, 20, 30, each unit cell 7a, 7b, 7c1, 7c2 exists in a stacked form. Here, a continuous single second separator 9a, 9b, 9c is provided around each unit cell 7a, 7b, 7c1, 7c2. Figures 11 to 13 , are shown to be interposed in various forms between adjacent unit cells 7a, 7b, 7c1, 7c2 facing each other, so that the second separator can be used as a separator between the unit cells 7a, 7b, 7c1, 7c2.

[0060] Figure 14 An embodiment of a structure for manufacturing a stack-folding type electrode assembly according to the related art is shown. Figure 14 The structure for manufacturing a stacked-folding type electrode assembly shown in uses a single cell including a first separator 1030 and a positive electrode 1010 and a negative electrode 1050 arranged on both sides of the first separator 1030, wherein the single cells 1100, 1200, 1300, 1400, 1500 are arranged on one surface of a second separator 1090 at predetermined intervals.

[0061] Furthermore, in the process of manufacturing the electrode assembly, after the electrode assembly is formed, the electrode assembly undergoes a pressing step.

[0062] According to another embodiment of the present disclosure, in the structure of manufacturing a stacked-folding type electrode assembly, a bi-cell (positive electrode / separator / negative electrode / separator / positive electrode structure or negative electrode / separator / positive electrode / separator / negative electrode structure) in which a first separator is provided on each of the two surfaces of the positive electrode or the negative electrode and the negative electrode or the positive electrode is provided on the first separator may be used instead of a single cell.

[0063] Figure 15 This is a schematic diagram illustrating the structure of a stacked-folding type electrode assembly manufactured using bicells. Bicells 2100, 2200, 2300, 2400, and 2500 are arranged at predetermined intervals on one surface of a second separator 2090. Bicells 2100, 2200, 2300, 2400, and 2500 may have a structure of positive electrode 2010 / first separator 2030 / negative electrode 2050 / first separator 2030 / positive electrode 2010 or a structure of negative electrode 2050 / first separator 2030 / positive electrode 2010 / first separator 2030 / negative electrode 2050. When the bibatteries 2100, 2200, 2300, 2400, and 2500 are used, preferably, when winding, bibatteries having a structure of positive electrode 2010 / first separator 2030 / negative electrode 2050 / first separator 2030 / positive electrode 2010 and bibatteries having a structure of negative electrode 2050 / first separator 2030 / positive electrode 2010 / first separator 2030 / negative electrode 2050 are appropriately arranged in such a manner that the positive electrode and the negative electrode meet on surfaces of one bibattery and another bibattery facing each other, as shown in FIG. Figures 11 to 13 As shown in .

[0064] When the structure for manufacturing the electrode assembly is prepared as described above, as Figures 11 to 13 As shown in , an electrode assembly is manufactured from the structure using a stack-folding process. Specifically, the structure is folded in a direction in which the second separator can surround the single cell or the bi-cell, and the single cells or the bi-cells can be aligned corresponding to each other in a stacked form.

[0065] exist Figure 14 and Figure 15 In the present disclosure, the structure of the Figure 11 The folding direction of the electrode assembly shown in FIG is indicated by an arrow mark, and the folding point is indicated by a dotted line.

[0066] As shown in the figure, when the structure is folded from the right end, there are areas where no single cells or dual cells are set, which are approximately as many as the width of one single cell 1100 or dual cell 2100, so that the electrodes 1010, 2010 located at the top of each single cell 1100 or dual cell 2100 can contact the second separator 1090, 2090.

[0067] Then, folding is continuously performed at the points indicated by the dotted lines in the direction marked by the arrows, and the single cells 1100, 1200, 1300, 1400, 1500 or the bi-cells 2100, 2200, 2300, 2400, 2500 are all surrounded by the second separators 1090, 2090, and the second separators 1090, 2090 are interposed between adjacent single cells or bi-cells, and the single cells or bi-cells have a structure aligned with each other in a stacked (stack-folded) form. However, in order to perform the stack-folding process, as shown in FIG. Figure 14 and Figure 15 The intervals between the single cells 1200, 1300, 1400, 1500 and the dual cells 2200, 2300, 2400, 2500 shown in FIG. 1 after the first single cell 1100 and the dual cell 2100 correspond to the height of the cells stacked before each single cell or dual cell, so it is obvious to those skilled in the art that the intervals gradually increase. However, it should be noted that in order to Figure 14 and Figure 15 For convenience of depiction, uniform spacing is shown.

[0068] When manufacturing electrode assemblies, especially stacked-folding type electrode assemblies, the entire interface between the electrode and the separator is bonded by high-temperature pressing. Therefore, the high-temperature pressing causes the separator to have an increased air permeability time, which ultimately leads to an increase in resistance, thereby affecting the performance of the battery. In addition, the separator exhibits a reduced dielectric breakdown voltage, which leads to safety issues. In addition, due to the interfacial adhesion between the electrode and the separator, the electrolyte wetting characteristics deteriorate, which undesirably affects the output characteristics.

[0069] An improved method of manufacturing an electrode assembly according to the present disclosure solves the above-mentioned problems by using a pair of surface-patterned rollers in a pressing step during the manufacturing of the electrode assembly.

[0070] The method for manufacturing an electrode assembly according to the present disclosure includes at least one step selected from the following steps: passing a heat-treated first diaphragm and an electrode between a pair of surface-patterned rollers and pressing them to prepare a preliminary electrode assembly in which the first diaphragm and the electrode are laminated; and passing a second diaphragm on which the preliminary electrode assembly is provided is pressed between a pair of surface-patterned rollers, and then winding them in such a manner that the second diaphragm can be inserted between the preliminary electrode assemblies.

[0071] According to one embodiment of the present disclosure, there is provided a method including applying pressure by using a pair of surface-patterned rollers only when preparing a preliminary electrode assembly.

[0072] Specifically, a method for manufacturing an electrode assembly is provided, comprising the following steps:

[0073] heat-treating the plurality of electrodes and a first separator interposed between the electrodes;

[0074] passing the heat-treated first separator and the electrode between a pair of surface-patterned rollers to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated;

[0075] disposing a plurality of preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; and

[0076] The winding is performed in such a manner that the second separator can be interposed between the preliminary electrode assemblies.

[0077] According to another embodiment of the present disclosure, there is provided a method including applying pressure by using a pair of surface-patterned rollers only when pressurizing a second separator having a plurality of preliminary electrode assemblies provided thereon.

[0078] Specifically, a method for manufacturing an electrode assembly is provided, comprising the following steps:

[0079] heat-treating the plurality of electrodes and a first separator interposed between the electrodes;

[0080] passing the heat-treated first separator and the electrode between a pair of rollers having unpatterned surfaces to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated;

[0081] disposing a plurality of preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; and

[0082] The second separator having the preliminary electrode assembly provided thereon is passed between a pair of rollers having patterned surfaces to be pressed, and then wound in such a manner that the second separator can be interposed between the preliminary electrode assemblies.

[0083] According to still another embodiment of the present disclosure, there is provided a method including pressing by using a pair of surface-patterned rollers not only when preparing a preliminary electrode assembly but also when pressing a second separator having a plurality of preliminary electrode assemblies provided thereon.

[0084] Specifically, a method for manufacturing an electrode assembly is provided, comprising the following steps:

[0085] heat-treating the plurality of electrodes and a first separator interposed between the electrodes;

[0086] passing the heat-treated first separator and the electrode between a pair of surface-patterned rollers to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated;

[0087] disposing a plurality of preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; and

[0088] The second separator having the preliminary electrode assembly provided thereon is passed between a pair of rollers having patterned surfaces to be pressed, and then wound in such a manner that the second separator can be interposed between the preliminary electrode assemblies.

[0089] Figure 1 A surface-patterned roller according to an embodiment of the present disclosure is illustrated.

[0090] Reference Figure 1 The surface-patterned roller 100 can be formed by directly engraving the pattern 120 on the surface of the roller body 110 or by attaching a separate pattern sheet to the roller surface. The method of engraving the pattern on the roller surface can be performed by engraving a portion having a desired pattern shape in an intaglio manner or by engraving a portion having a desired pattern shape in a relief manner.

[0091] Figures 2 to 4 Illustrated are patterns engraved directly on the surface of the roller in various shapes.

[0092] exist Figure 2 In the , a quadrilateral pattern is formed by intaglio. Figure 3 In the figure, a quadrilateral pattern is formed by relief carving.

[0093] exist Figure 4 , a pattern of a honeycomb structure is shown, in which the hexagonal shape retains only the edge portion as the pattern side, while the rest is removed by intaglio engraving.

[0094] Furthermore, the surface-patterned roller according to an embodiment of the present disclosure may be prepared by attaching a separate pattern sheet (pattern member) having a desired pattern to the surface of the roller.

[0095] Compared to conventional rollers with non-patterned surfaces, i.e., rollers with flat surfaces without surface irregularities, the surface-patterned rollers according to embodiments of the present disclosure exhibit reduced contact area with the electrodes and / or separators facing the rollers, thereby reducing the pressing (lamination) load of the electrode assembly, thereby reducing the physical stimulation applied to the separators and electrodes. By controlling the shape of the pattern formed on the surface and the exposed surface area, the contact area and contact area distribution of the roller directly facing the electrodes, etc. can be freely controlled.

[0096] When a roller with a patterned surface comes into contact with an electrode facing it during the lamination process, the portion where the pattern is formed but not in direct contact with the electrode (the surface portion removed by engraving or embossing, the original roller surface to which the pattern sheet is not attached, etc.) can reduce the lamination load, thereby reducing the physical stimulation applied to the diaphragm and the electrode.

[0097] The pattern formed on the roller may include a hexagonal pattern, a quadrilateral pattern, a triangular pattern, a circular pattern, a pentagonal pattern, a straight line pattern, a diagonal line pattern, a polygonal pattern, or a combination of two or more thereof.

[0098] According to one embodiment of the present disclosure, using a roller with a honeycomb-patterned surface maximizes bonding effectiveness with a minimal bonding area, utilizing the most stable structure. Consequently, in the final electrode assembly, the air permeability and electrolyte wetting properties of the separator at the portion not directly pressed can be further improved.

[0099] According to one embodiment of the present disclosure, the area of the pattern directly facing the electrode can be 1% to 99% of the total surface area of the roller based on the surface patterning. When the pattern directly facing the electrode meets the above-defined range, the pressure area can be reduced and the physical stimulation applied to the electrode and the separator can be minimized.

[0100] Figure 5 The diagram illustrates a process for preparing a preliminary electrode assembly in which the first separator and electrodes are laminated by heat-treating a plurality of electrodes and a first separator interposed between the electrodes, and then pressing the heat-treated first separator and electrodes between a pair of surface-patterned rollers. A positive electrode having positive electrode active material layers 220 and 230 formed on both surfaces of a positive electrode current collector 210 and a negative electrode having negative electrode active material layers 260 and 270 formed on both surfaces of a negative electrode current collector 250 are passed through a heat source 400 with a separator 240 interposed between the two electrodes. The heat-treated separator and electrodes are then pressed between a pair of rollers 100 having patterns 120 formed on the surfaces of roller bodies 110, thereby obtaining preliminary electrode assembly 200.

[0101] Here, the heat treatment may be performed at a temperature of 25° C. to 100° C. for a time of 0.01 seconds to 10 seconds by using a heater.

[0102] Furthermore, the pressing conditions (pressure, time, etc.) in the process of pressing the heat-treated separator and electrode by the pair of rollers 100 having the patterns 120 formed on their surfaces can be flexibly changed according to the requirements of adhesion and air permeability.

[0103] in addition, Figure 6aA conventional pressing roller, ie, a roller 500 having a non-patterned flat surface 520 without surface irregularities on the surface of a roller body 510 is illustrated. Figure 6b The diagram illustrates a process of preparing a preliminary electrode assembly in which the first separator is laminated with the electrodes by heat-treating a plurality of electrodes and a first separator interposed between the electrodes, and pressing the heat-treated first separator and the electrodes through a pair of rollers having unpatterned surfaces.

[0104] Figure 7 A preliminary electrode assembly 10P obtained by using a pair of surface-patterned rollers according to an embodiment of the present disclosure is illustrated.

[0105] Figure 7 The preliminary electrode assembly 10P shown in the figure includes: a pair of first electrodes 600, the first electrode 600 having first electrode layers 620 and 630 formed on both surfaces of a first electrode current collector 610; a second electrode 700, the second electrode 700 having second electrode layers 720 and 730 formed on both surfaces of a second electrode current collector 710; and a separator 800, the separator 800 being interposed between each first electrode and the second electrode and having an organic / inorganic porous coating formed on both surfaces of a porous polymer substrate 810. Here, Figure 7 The porous coating layer of the separator of the preliminary electrode assembly 10P can be divided into a contact area 820 that is in direct contact with the patterned portion of the roller during the pressing process, and a non-contact area 830 that is not in direct contact with the patterned portion but faces the non-patterned portion. Here, compared with the contact area 820, the non-contact area 830 that is not in direct contact with the patterned portion experiences a relatively low level of pressing strength (lamination strength) and is therefore less dense. As a result, when the final preliminary electrode assembly is applied to an electrochemical device, the electrolyte can easily enter the separator through the less dense non-contact area 830 of the separator, significantly improving the electrolyte wettability of the electrode assembly. In addition, the gas permeation time (Gurley number) of the separator can be minimized, thereby improving the performance of the electrochemical device. Here, during the pressing process, an area in direct contact with the patterned portion of the roller and its lower area may also be formed at positions in the first electrode layer 620, 630 and the second electrode layer 720, 730 corresponding to the contact area 820 and the non-contact area 830 of the diaphragm, that is, the contact areas 620a, 630a of the first electrode layer 620, 630; and the contact areas 720a, 730a of the second electrode layer 720, 730.

[0106] on the contrary, Figure 8 A preliminary electrode assembly 20P obtained by using a conventional unpatterned roller is illustrated. Figure 8, the porous coating layer of the separator includes only the contact area 820 that is in direct contact with the patterned portion of the roller during the pressing process, and does not include any non-contact area that is not in direct contact with the patterned portion.

[0107] According to one embodiment of the present disclosure, a plurality of preliminary electrode assemblies may be arranged on one surface of a second diaphragm while being spaced apart from each other, the second diaphragm on which the preliminary electrode assemblies are arranged may be pressed between a pair of surface-patterned rollers, and then may be wound in such a manner that the second diaphragm may be inserted between the preliminary electrode assemblies.

[0108] Reference Figure 9 and Figure 10 The preliminary electrode assembly disposed on one surface of the second separator 1000 may be a preliminary electrode assembly 10P obtained by using a pair of surface-patterned rollers or a preliminary electrode assembly 20P obtained by using a pair of surface-unpatterned rollers.

[0109] Furthermore, in the pressing process using a pair of surface-patterned rollers, the pressing conditions (pressure, time, etc.) to which the preliminary electrode assembly disposed on one surface of the second separator 1000 is subjected can be flexibly varied according to adhesion and air permeability requirements.

[0110] When the electrode assembly is completed as described above, it is housed in a case and sealed using a conventional method, thereby providing an electrochemical device. Preferably, the electrochemical device may be a lithium secondary battery.

[0111] [Description of main components]

[0112] 10, 20, 30: electrode assembly 3a, 3b, 3c: first separator

[0113] 1a, 1b, 1c, 2050: negative electrode 5a, 5b, 5c, 2010: positive electrode

[0114] 7a, 7b, 7c1, 7c2, 1100, 1200, 1300, 1400, 1500: Cells

[0115] 3a, 3b, 3c, 1030, 2030: first separator 7a, 7b: full battery

[0116] 7c1, 7c2, 2100, 2200, 2300, 2400, 2500: Dual battery

[0117] 9a, 9b, 9c, 1000, 1090: Second diaphragm

[0118] 100, 500: Roller 110, 510: Roller body 120: Pattern 520: Surface

[0119] 210: Positive electrode current collector 220, 230: Positive electrode active material layer

[0120] 250: Negative electrode current collector 260, 270: Negative electrode active material layer 240: Separator

[0121] 10P, 20P, 200: Preliminary electrode assembly

[0122] 610: First electrode current collector 620, 630: First electrode layer 600: First electrode

[0123] 710: Second electrode current collector 720, 730: Second electrode layer 700: Second electrode

[0124] 810: porous polymer substrate

[0125] 800: Diaphragm 820: Contact area 830: Non-contact area.

Claims

1. A method for manufacturing a stacked-folding type electrode assembly, comprising the following steps: heat-treating a plurality of electrodes and a first separator interposed between the electrodes; Passing the heat-treated first separator and the electrode between a pair of rollers having unpatterned surfaces or a pair of rollers having patterned surfaces to be pressed, thereby preparing a preliminary electrode assembly in which the first separator and the electrode are laminated; disposing a plurality of the preliminary electrode assemblies on one surface of a second separator while being spaced apart from each other; as well as The second separator having the preliminary electrode assembly disposed thereon is pressed by passing between a pair of rollers having patterned surfaces, and then wound in such a manner that the second separator is interposed between the preliminary electrode assemblies. 2 . The method of manufacturing a stacked-folding type electrode assembly according to claim 1 , wherein the surface-patterned roller is formed by engraving a pattern on a roller surface or by attaching a pattern sheet to a roller surface.

3. The method for manufacturing a stacked-folding type electrode assembly according to claim 1, wherein the pattern formed on the surface-patterned roller comprises a hexagonal pattern, a quadrilateral pattern, a triangular pattern, a circular pattern, a pentagonal pattern, a straight line pattern, a diagonal line pattern, or a combination of two or more of the above patterns. 4 . The method of manufacturing a stacked-folding type electrode assembly according to claim 1 , wherein an area of the pattern formed on the surface-patterned roller directly facing the electrode is 1% to 99% based on a total surface area of the surface-patterned roller. 5 . A stack-folding type electrode assembly obtained by the method according to claim 1 . 6 . An electrochemical device comprising the stack-folding type electrode assembly according to claim 5 housed in a case. The electrochemical device according to claim 6 , wherein the electrochemical device is a lithium secondary battery.

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