Apparatus for manufacturing electrode assembly for preventing separator from being folded and electrode assembly manufactured by the same

Abstract

The present invention relates to an electrode assembly manufacturing apparatus including a first separator supplying unit that supplies a first separator sheet from a first separator roll, a first electrode supplying unit that cuts a first electrode coming out of a first electrode roll to supply a first unit electrode, a second separator supplying unit that supplies a second separator sheet from a second separator roll, a wrinkle prevention unit that holds the first separator sheet and the second separator sheet and applies tension, a surface treatment unit that forms a fine embossed pattern on the first separator sheet and the second separator sheet, a lamination unit that heats and presses the first separator sheet, a first unit electrode, and a second separator sheet to adhere them, and a cutting unit that cuts the first separator sheet and the second separator sheet, and thereby it is possible to prevent wrinkles from occurring in the separator during the manufacturing process of the electrode assembly, thereby preventing the production of defective electrode assemblies.

Description

[Technical field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 2022-0061860 filed on May 20, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to an electrode assembly manufacturing apparatus for preventing a separator from being folded, and an electrode assembly manufactured by the same. More specifically, the present invention relates to an electrode assembly manufacturing apparatus that can prevent a separator from being folded by forming a fine relief pattern on a portion of a separator sheet to be cut in a state where the separator sheet is tautly spread, and an electrode assembly manufactured by the same. [Background technology]

[0003] Lithium secondary batteries are rechargeable and have high energy density, and are attracting attention as a new energy source with environmentally friendly characteristics, as they can dramatically reduce the use of fossil fuels and do not produce by-products due to energy consumption.

[0004] Lithium secondary batteries have been attracting attention not only as energy sources for wearable or portable devices, but also for devices having high power and high energy density, such as electric vehicles.

[0005] The lithium secondary battery may form a battery cell, which is a unit structure in which an electrode assembly, in which a positive electrode and a negative electrode are stacked with a separator sandwiched therebetween, is housed in a battery case together with an electrolyte.

[0006] The electrode assembly includes a half-cell in which one electrode is disposed between two separators and stacked, and a mono-cell in which two electrodes of opposite polarity are stacked with a separator disposed on one side.

[0007] In order to manufacture the half cell and mono cell, two separators and electrodes are arranged to completely overlap in the lamination direction, and then a lamination process is performed in which heat and pressure are applied to bond them together.

[0008] Generally, a separator is designed to have a larger area than an electrode to ensure insulation between opposite polarities, but a defective electrode assembly may occur in which the separator breaks or wrinkles during a transfer process for manufacturing an electrode assembly. If the defective electrode assembly is manufactured into a battery cell, a short circuit may occur between electrodes of opposite polarities.

[0009] Therefore, various attempts have been made to prevent the separator from breaking and to minimize the occurrence of defective electrode assemblies.

[0010] Patent Document 1 relates to an electrode assembly manufacturing device that performs a joining process with electrodes aligned in a desired position; before the electrode is inserted into the joining section, a gripper fixes the electrode in a fixed position, and a guide roller transports the electrode aligned in the fixed position to the joining section, thereby preventing the electrode from shifting or the occurrence of steps.

[0011] However, Patent Document 1 does not present any technology for preventing folding of the separation membrane.

[0012] Patent Document 2 relates to an electrode assembly manufacturing method and device for correcting electrode meandering, and includes a meandering correction process for measuring the center position of the electrode using a vision sensor, and moving the electrode and separation membrane in the X-axis direction, which is the electrode travel direction, and the Y-axis direction, which is the electrode width direction, to correct position deviation by moving the positions of the electrode and separation membrane during electrode assembly manufacturing.

[0013] Patent Document 2 discloses a method and apparatus for aligning the positions of an electrode and a separator prior to a bonding process for bonding the electrode and the separator, but does not provide a technology that can solve problems such as the separator being broken during the transportation of the electrode assembly.

[0014] Therefore, there is a need for a technology that can prevent defective electrode assemblies from being produced during the lamination process by preventing folding of the separator laminated with the electrodes when manufacturing the electrode assembly. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] Korean Patent Publication No. 2017-0114351 [Patent Document 2] Korean Patent Publication No. 2021-0058170 Summary of the Invention [Problem to be solved by the invention]

[0016] The present invention has been made to solve the above problems, and an object of the present invention is to provide an electrode assembly manufacturing apparatus capable of performing lamination without wrinkles or folds in a separator of an electrode assembly, thereby preventing defects in the electrode assembly, and an electrode assembly manufactured by the same. [Means for solving the problem]

[0017] To achieve the above object, an electrode assembly manufacturing apparatus according to the present invention may include a first separator supplying unit that supplies a first separator sheet from a first separator roll, a first electrode supplying unit that cuts a first electrode coming out of a first electrode roll to supply a first unit electrode, a second separator supplying unit that supplies a second separator sheet from a second separator roll, a wrinkle prevention unit that holds the first separator sheet and the second separator sheet and applies tension, a surface treatment unit that forms a fine embossed pattern on the first separator sheet and the second separator sheet, a lamination unit that heats and presses the first separator sheet, the first unit electrode, and the second separator sheet to adhere them, and a cutting unit that cuts the first separator sheet and the second separator sheet.

[0018] In addition, the laminate may further include a second electrode supplying unit that cuts the second electrode coming out of the second electrode roll and supplies a second unit electrode, and the lamination unit may press and attach the first separator sheet, the first unit electrode, the second separator sheet, and the second unit electrode.

[0019] The surface treatment portion may be located within the wrinkle prevention portion.

[0020] The surface treatment unit may be disposed after the wrinkle prevention unit.

[0021] The wrinkle prevention unit can include a pair of first grippers that grip both ends parallel to the running direction of the first separation membrane sheet, and a pair of second grippers that grip both ends parallel to the running direction of the second separation membrane sheet.

[0022] The pair of first grippers and the pair of second grippers can pull both ends of the first separation membrane sheet and the second separation membrane sheet so that the first separation membrane sheet and the second separation membrane sheet are in a taut state.

[0023] The first gripper and the second gripper are configured such that a plurality of unit grippers are arranged on a circulating transfer line, and the circulating transfer line can transfer the plurality of unit grippers at the same speed as the transfer speed of the first separation membrane sheet and the second separation membrane sheet.

[0024] The plurality of unit grippers may have a shape capable of moving individually toward or away from the first and second separation membrane sheets.

[0025] The surface treatment section includes a first surface treatment section for surface treatment of the first separation membrane sheet and a second surface treatment section for surface treatment of the second separation membrane sheet, and the first surface treatment section and the second surface treatment section are composed of a lower die and an upper punch, and fine protrusions may be formed on the upper punch.

[0026] The surface treatment unit may form a fine relief pattern at the portion where the first and second separator sheets are cut.

[0027] In a state in which the first separation membrane sheet and the second separation membrane sheet are arranged to overlap each other, the fine relief pattern formed on the first separation membrane sheet and the fine relief pattern formed on the second separation membrane sheet may be arranged to overlap each other.

[0028] The present invention provides an electrode assembly manufactured by the electrode assembly manufacturing apparatus, wherein outer peripheries of a first separator and a second separator include excess portions extending beyond outer peripheries of first unit electrodes, and a fine relief pattern may be formed on the excess portions of the first separator and the second separator.

[0029] The electrode assembly may be a half cell in which a first separator, a first unit electrode, and a second separator are sequentially stacked, or a mono cell in which a first separator, a first unit electrode, a second separator, and a second unit electrode are sequentially stacked.

[0030] Furthermore, the present invention can provide the above-mentioned means for solving problems in the form of various combinations. Effect of the Invention

[0031] As described above, the present invention allows lamination to be performed while maintaining the separator sheet in a taut state.

[0032] In addition, since the fine relief pattern is formed on the separator sheet, it is possible to prevent slippage between two overlapping separator sheets. [Brief description of the drawings]

[0033] [Figure 1] 1 is a schematic diagram of an electrode assembly manufacturing apparatus according to the present invention; [Diagram 2] FIG. 2 is a plan view of a state in which a wrinkle prevention unit according to the present invention grips a separation membrane sheet. [Diagram 3] FIG. 3 is a perspective view of FIG. 2. [Figure 4] FIG. 2 is a side view of the wrinkle prevention unit according to the present invention. [Diagram 5] FIG. 2 is a front view of the wrinkle prevention unit according to the present invention. [Figure 6] FIG. 2 is a plan view of a separation membrane sheet on which a fine relief pattern is formed. [Figure 7] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] Hereinafter, a detailed description will be given of an embodiment of the present invention that can be easily implemented by a person having ordinary skill in the art to which the present invention pertains, with reference to the accompanying drawings. However, when describing the operation principle of the preferred embodiment of the present invention in detail, detailed description of related well-known functions or configurations may be omitted if it is determined that such detailed description may unnecessarily obscure the gist of the present invention.

[0035] In addition, the same reference numerals are used throughout the drawings for parts having similar functions and actions. Throughout the specification, when a part is said to be connected to another part, this includes not only the case where the part is directly connected to another part, but also the case where the part is indirectly connected via another element between the two parts. In addition, when a part includes a certain component, it does not mean that the other component is excluded, but that the part may further include the other component, unless otherwise specified.

[0036] Furthermore, descriptions that limit or add specific elements are applicable to all inventions and are not limited to a particular invention unless otherwise specified.

[0037] Furthermore, throughout the description of the present invention and the claims, the singular includes the plural unless otherwise stated.

[0038] In addition, throughout the description of the present invention and the claims, unless otherwise stated, "or" includes "and." Therefore, "including A or B" means three cases: including A, including B, or including both A and B.

[0039] The invention will now be explained with reference to the drawings and in conjunction with detailed embodiments.

[0040] FIG. 1 is a schematic diagram of an electrode assembly manufacturing apparatus according to the present invention.

[0041] Referring to FIG. 1, the electrode assembly manufacturing apparatus according to the present invention includes a first separator supplying unit 100 for supplying a first separator sheet 110 from a first separator roll, a first electrode supplying unit 200 for cutting a first electrode 210 coming out of a first electrode roll and supplying a first unit electrode 211, a second separator supplying unit 300 for supplying a second separator sheet 310 from a second separator roll, a wrinkle prevention unit 500 for holding the first separator sheet 110 and the second separator sheet 310 and applying tension thereto, a surface treatment unit 600 for forming a fine embossed pattern on the first separator sheet 110 and the second separator sheet 310, a lamination unit 700 for heating and pressing the first separator sheet 110, the first unit electrode 211, and the second separator sheet 310 to adhere them to each other, and a cutting unit 800 for cutting the first separator sheet 110 and the second separator sheet 310.

[0042] In this manner, the first separator sheet 110, the first unit electrode 211, and the second separator sheet 310 supplied from the first separator supply unit 100, the first electrode supply unit 200, and the second separator supply unit 300, respectively, are heat-sealed, and the first separator sheet 110 and the second separator sheet 310 are cut in the cutting unit 800, thereby manufacturing an electrode assembly in the form of a half cell.

[0043] In addition, the lamination unit 700 may further include a second electrode supplying unit 400 that cuts the second electrode 410 coming out of the second electrode roll and supplies the second unit electrode 411. The lamination unit 700 may press and attach the first separator sheet 110, the first unit electrode 211, the second separator sheet 310, and the second unit electrode 411 to manufacture a mono-cell type electrode assembly.

[0044] That is, the present invention includes a wrinkle prevention unit 500 to prevent the separator sheet from folding or from being wrinkled when manufacturing an electrode assembly including at least two separator sheets.

[0045] In addition, the separator membrane sheets include a surface treatment section 600 that forms a fine relief pattern on the surfaces facing each other to prevent slippage during transportation by increasing the friction between the two or more separator membrane sheets facing each other.

[0046] The wrinkle prevention unit 500 grips and pulls the outer peripheries of the first separation membrane sheet 110 and the second separation membrane sheet 310 so as to keep them taut in order to prevent wrinkles from occurring in the first separation membrane sheet 110 and the second separation membrane sheet 310.

[0047] Since the wrinkle prevention unit 500 is disposed before the lamination unit 700, it is possible to prevent wrinkles from occurring in the separator sheet before the stacked body including the separator sheet and the electrodes enters the lamination unit 700. Therefore, when the stacked body including the separator sheet and the electrodes is attached by heating and pressing in the lamination unit 700, the electrodes and the separator sheet can be attached in a flat state.

[0048] In this manner, when the electrode assembly manufacturing apparatus of the present invention is used, the occurrence of folding or wrinkling of the separator can be prevented, and therefore the problem of contact between electrodes of opposite polarities caused by poor attachment of the separator can be solved.

[0049] In one embodiment, when the surface treatment unit 600 is located within the wrinkle prevention unit 500, a process of forming a fine embossed pattern on the outer surfaces of the first separator sheet 110 and the second separator sheet 310 can be performed while the first separator sheet 110 and the second separator sheet 310 are kept taut.

[0050] Alternatively, the surface treatment unit 600 can be disposed downstream of the wrinkle prevention unit 500, so that when the first separation membrane sheet 110 and the second separation membrane sheet 310, which have been put into a taut state by the wrinkle prevention unit 500, are moved to the surface treatment unit 600, the surface treatment unit 600 can form a fine relief pattern on the first separation membrane sheet 110 and the second separation membrane sheet 310.

[0051] Fig. 2 is a plan view of the wrinkle prevention unit according to the present invention gripping a separation membrane sheet, Fig. 3 is a perspective view of Fig. 2, and Fig. 4 is a side view of the wrinkle prevention unit according to the present invention. Figs. 2 and 3 show one separation membrane sheet and the wrinkle prevention unit gripping it, and the one separation membrane sheet includes a first separation membrane sheet 110 and a second separation membrane sheet 310. Therefore, the description of the first separation membrane sheet 110 in Figs. 2 and 3 can be similarly applied to the second separation membrane sheet.

[0052] In addition, although Figures 2 to 4 show only the first gripper 510 that grips the first separation membrane sheet, the description below of the first gripper 510 that grips the first separation membrane sheet 110 can be similarly applied to the second gripper that grips the second separation membrane sheet 310.

[0053] 2 to 4, the wrinkle prevention unit 500 according to the present invention includes a pair of first grippers 510 for gripping both ends parallel to the running direction A of the first separation membrane sheet 110, and a pair of second grippers for gripping both ends parallel to the running direction of the second separation membrane sheet.

[0054] Although the second gripper is not shown in the drawing, a second separator sheet and a second gripper gripping the second separator sheet may be disposed above the first separator sheet 110 and the first gripper 510 gripping the second separator sheet.

[0055] The first unit electrodes 211 are arranged on the upper surface of the first separator sheet 110 along the traveling direction A so as to be spaced apart at a predetermined interval. Excess portions extending from the ends of the first unit electrodes 211 are located on both ends of the first separator sheet 110 parallel to the traveling direction A, so that the first gripper 510 grips the excess portions.

[0056] Therefore, the first unit electrode 211 can be prevented from being damaged by the first gripper 510 gripping the first separation membrane sheet 110.

[0057] The first gripper 510 and the second gripper pull both ends of the first separation membrane sheet 110 and the second separation membrane sheet 310 so that the first separation membrane sheet 110 and the second separation membrane sheet 310 are in a taut state. That is, the pair of first grippers 510 pull the first separation membrane sheet 110 in a direction that increases the distance between them, so that the first separation membrane sheet 110 is in a taut state.

[0058] 2 to 4 show a configuration in which 16 pairs of first grippers 510, each consisting of one pair, are arranged on the circulating transfer line 520 along the running direction A of the first separation membrane sheet 110, but the number of pairs of first grippers arranged on the circulating transfer line 520 is not limited to this.

[0059] The circulating transfer lines 520 are located at both ends of the first separation membrane sheet 110 parallel to the running direction A, and a plurality of unit grippers 511 are arranged at predetermined intervals on each circulating transfer line 520 .

[0060] The circulating transfer line 520 transfers a plurality of unit grippers 511 while running at the same speed as the transfer speed of the first separator sheet 110 and the second separator sheet 310 .

[0061] FIG. 5 is a front view of the wrinkle prevention unit according to the present invention.

[0062] Referring to FIG. 5, a plurality of unit grippers 511 may include an upper unit and a lower unit, and one side end of the upper unit and the lower unit may function as a kind of rotation axis when connected, and the other side end may have a deformable shape so that it can be repeatedly opened and closed based on the rotation axis.

[0063] Specifically, when the multiple unit grippers 511 move along the circulating transfer line 520 with the upper and lower units spread out as shown in the upper part of FIG. 5 and approach the first separation membrane sheet 110, they are deformed into a closed state as shown in the lower part of FIG. 5 in order to grip both ends of the first separation membrane sheet 110 parallel to the running direction A, and a tension that pulls the first separation membrane sheet 110 can be applied.

[0064] When the process of pulling the separator membrane sheet while moving along the circulating transfer line 520 is completed, the unit grippers 511 release the first separator membrane sheet 110 that they have been holding, and are deformed into the shape shown in the upper part of FIG.

[0065] In addition, when the multiple unit grippers 511 move along the circulating transfer line 520 and approach the separation membrane sheet, they move closer to the separation membrane sheet and grip the excess portion around the outer periphery of the separation membrane sheet while changing from an open state to a closed state. Then, to make the separation membrane sheet taut, both ends are pulled away from each other. In this way, when the process of pulling the separation membrane sheet is completed, the closed state of the unit grippers can change from an open state to a closed state and move away from the separation membrane sheet.

[0066] That is, in order to use multiple unit grippers to manage the entire continuously moving separation membrane sheet so that it is kept taut, the multiple unit grippers 511 may have a shape that allows them to move individually toward or away from the separation membrane sheet.

[0067] FIG. 6 is a plan view of a separation membrane sheet on which a fine relief pattern is formed, and FIG. 7 is a perspective view of a surface treatment section.

[0068] FIG. 6 shows one separator sheet and electrodes arranged thereon at a predetermined interval, and the separator sheet shown in FIG. 6 includes a first separator sheet and a second separator sheet.

[0069] FIG. 7 shows two types of surface treatment sections, including a first surface treatment section for surface treatment of a first separation membrane sheet and a second surface treatment section for surface treatment of a second separation membrane sheet, and each of the surface treatment sections shown in FIG. 7 can be applied as the first surface treatment section and the second surface treatment section.

[0070] 6 and 7, the first and second surface treatment sections are composed of a lower die 620 and an upper punch 610, and fine protrusions 611 are formed on the lower surface of the upper punch 610.

[0071] The shape of the fine protrusions 611 is not particularly limited as long as it can form a fine relief pattern on the surface when the separator sheet is pressed, and can be formed in a variety of shapes, such as linear, curved, hemispherical, cylindrical, prismatic, etc., and can be formed on all or part of the lower surface of the upper punch.

[0072] Meanwhile, since the upper surface 621 of the lower die 620 has a flat shape, the fine relief pattern 601 is formed on the upper surface of the first separator sheet 110 pressed by the upper punch having the fine protrusions 611, and the lower surface facing the lower die can be flat without the fine relief pattern.

[0073] When the first separation membrane sheet 110 and the second separation membrane sheet are arranged in an overlapping state, the fine relief pattern 601 formed on the first separation membrane sheet 110 and the fine relief pattern 601 formed on the second separation membrane sheet may be arranged to overlap each other.

[0074] In addition, the portion where the fine embossed pattern 601 is formed by the surface treatment unit may be the portion where the first separation membrane sheet 110 and the second separation membrane sheet 310 are cut. If the fine embossed pattern 601 is formed such that the center of the fine embossed pattern 601 is positioned on the cutting line 630, when the first separation membrane sheet 110 and the second separation membrane sheet 310 are cut, the cut first separation membrane (first separation membrane 111 in FIG. 1) and second separation membrane (second separation membrane 311 in FIG. 1) can be maintained attached to each other due to the frictional force generated by the fine embossed pattern 601.

[0075] The electrode assembly manufactured by the electrode assembly manufacturing apparatus may be a half cell in which a first separator, a first unit electrode, and a second separator are sequentially stacked, or a mono cell in which a first separator, a first unit electrode, a second separator, and a second unit electrode are sequentially stacked. The first unit electrode and the second unit electrode may be a positive electrode and a negative electrode, or a negative electrode and a positive electrode, respectively.

[0076] In the electrode assembly, the outer peripheries of the first and second separators include excess portions extending beyond the outer peripheries of the first unit electrodes, and the excess portions of the first and second separators may have fine relief patterns formed thereon. That is, the fine relief patterns are formed on both outer peripheries of the first and second separators that are parallel to each other, and the excess portions may increase friction between the separators due to the fine relief patterns.

[0077] Therefore, the excess portion of the separator can be prevented from being folded during a process of transporting the electrode assembly, stacking the electrode assemblies, and injecting an electrolyte in order to manufacture a battery cell by placing the electrode assembly in a battery case.

[0078] Those skilled in the art will appreciate that various applications and modifications within the scope of the present invention will be possible based on the above content. [Explanation of symbols]

[0079] 100 First separation membrane supply section 110 First separation membrane sheet 111 First separation membrane 200 1st electrode supply section 210 1st electrode 211 First unit electrode 300 Second separation membrane supply section 310 Second separation membrane sheet 311 Second separation membrane 400 Second electrode supply section 410 2nd electrode 411 Second unit electrode 500 Wrinkle prevention section 510 First Gripper 511 unit gripper 520 Transfer Line 600 Surface Treatment Section 601 Micro-relief pattern 610 Upper punch 611 Fine protrusions 620 Lower Die 621 Top surface 630 Cutting Line 700 Lamination Department 800 Cutting section

Claims

1. A first separation membrane supply unit that supplies a first separation membrane sheet from a first separation membrane roll; a first electrode supplying unit that cuts the first electrode coming out of the first electrode roll and supplies the first unit electrodes; A second separation membrane supply unit that supplies a second separation membrane sheet from the second separation membrane roll; A wrinkle prevention unit that holds the first separation membrane sheet and the second separation membrane sheet and applies tension to them; A surface treatment section for forming a fine relief pattern on the first separation membrane sheet and the second separation membrane sheet; a lamination unit that heats and presses the first separator sheet, the first unit electrode, and the second separator sheet to adhere them to each other; a cutting unit that cuts the first separation membrane sheet and the second separation membrane sheet; An electrode assembly manufacturing apparatus comprising:

2. The second electrode supplying unit may further include a second electrode supplying unit that cuts the second electrode coming out of the second electrode roll and supplies the second unit electrodes. 2 . The electrode assembly manufacturing apparatus of claim 1 , wherein the lamination unit presses and attaches the first separator sheet, the first unit electrode, the second separator sheet, and the second unit electrode.

3. The electrode assembly manufacturing apparatus according to claim 1 , wherein the surface treatment portion is located within the wrinkle prevention portion.

4. The electrode assembly manufacturing apparatus according to claim 1 , wherein the surface treatment unit is disposed after the wrinkle prevention unit.

5. 2. The electrode assembly manufacturing apparatus according to claim 1, wherein the wrinkle prevention unit includes a pair of first grippers that grip both ends parallel to the running direction of the first separator sheet, and a pair of second grippers that grip both ends parallel to the running direction of the second separator sheet.

6. 6. The electrode assembly manufacturing apparatus of claim 5, wherein the pair of first grippers and the pair of second grippers pull both ends of the first separator sheet and the second separator sheet so that the first separator sheet and the second separator sheet are in a taut state.

7. The first gripper and the second gripper are configured such that a plurality of unit grippers are arranged on the circulating transfer line, The electrode assembly manufacturing apparatus of claim 5 , wherein the circulating transfer line transfers the plurality of unit grippers at the same speed as a transfer speed of the first separator sheet and the second separator sheet.

8. The electrode assembly manufacturing apparatus of claim 7 , wherein the plurality of unit grippers are configured to be movable individually toward or away from the first separator sheet and the second separator sheet.

9. The surface treatment section includes a first surface treatment section for surface treatment of the first separation membrane sheet, and a second surface treatment section for surface treatment of the second separation membrane sheet, The first surface treatment section and the second surface treatment section are composed of a lower die and an upper punch, 2. The electrode assembly manufacturing apparatus according to claim 1, wherein the upper punch is formed with fine protrusions.

10. The electrode assembly manufacturing apparatus of claim 1 , wherein the surface treatment section forms the micro-relief pattern at a portion where the first separator sheet and the second separator sheet are cut.

11. 11. The electrode assembly manufacturing apparatus of claim 10, wherein the first separator sheet and the second separator sheet are arranged so as to overlap each other, and the fine relief pattern formed on the first separator sheet and the fine relief pattern formed on the second separator sheet are arranged so as to overlap each other.

12. An electrode assembly which is a half cell in which a first separation membrane, a first unit electrode, and a second separation membrane are sequentially stacked, or a mono cell in which a first separation membrane, a first unit electrode, a second separation membrane, and a second unit electrode are sequentially stacked, the first and second separators each include an excess portion extending beyond the outer periphery of the first unit electrode, The electrode assembly further comprises a micro-relief pattern formed on the excess portions of the first and second separators.

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