Jig for isostatic pressing of pouch cell and isostatic pressing method for pouch cell by using same

Abstract

The present invention provides a jig for isostatic pressing of a pouch cell and an isostatic pressing method for a pouch cell by using same, the jig for isostatic pressing of a pouch cell comprising: a lower plate having, at the center thereof, an opening portion into which a cup portion of a pouch cell can be inserted, and including an upper surface supporting a sealing portion of the pouch cell from below; and an upper plate coupled to the upper surface of the lower plate and including an opening portion overlapping the opening portion of the lower plate in an upper direction, and a lower surface pressing the sealing portion of the pouch cell from above, wherein the opening portions of the upper plate and the lower plate each have a transverse area wider than a transverse area of the cup portion of the pouch cell to be isostatically pressed, by 1% or more to 10% or less.

Description

Jig for isotropic pressurizing of a pouch cell and method for isotropic pressurizing of a pouch cell using the same

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0127975 dated September 23, 2024, and all contents disclosed in the document of said Korean patent application are incorporated herein as part of this specification.

[0002] The present invention relates to a jig for isotropically pressurizing a pouch cell and a method for isotropically pressurizing a pouch cell using the same.

[0003] Lithium-ion secondary batteries are classified into can-type secondary batteries, in which an electrode assembly is embedded in a metal can, and pouch-type secondary batteries, in which an electrode assembly is embedded in a pouch. The pouch-type secondary battery comprises an electrode assembly, an electrode lead coupled to the electrode assembly, and a pouch that accommodates the electrode assembly with the tip of the electrode lead drawn out to the outside.

[0004] Pouch-type secondary batteries are commercialized by housing an electrode assembly having a structure in which one or more unit cells, including a positive electrode, a negative electrode, and a separator interposed between them, are stacked in the cup portion of a pouch and then injecting an electrolyte, or by housing an electrode assembly equipped with a solid electrolyte from the beginning in the cup portion of a pouch and then sealing the sealing portion of the pouch.

[0005] Among these, all-solid-state batteries have the advantage of being superior in terms of safety. In the manufacturing process of all-solid-state batteries, a warm isostatic pressing (WIP) process is generally applied to bond the interface between the electrode and the solid electrolyte. This isostatic pressing is essential because if the interface between the electrode and the solid electrolyte is not properly formed, the movement of lithium (Li) ions becomes difficult, making battery operation impossible.

[0006] FIG. 1 is an exploded perspective view showing the form of a conventional pouch cell isotropic pressurizing jig and the form of a pouch cell receiving the same. That is, the conventional pouch cell isotropic pressurizing jig (1) is composed of an upper plate (1a) and a lower plate (1b), and the upper plate (1a) and the lower plate (1b) include an opening in the center that can receive the cup portion of the pouch cell.

[0007] In a conventional pouch cell isotropic pressurization jig (1), a relatively wide gap is formed between the cup portion (2a) and the opening of the pouch cell when the pouch cell (2) is contained, and the sealing portion (2b) of the pouch cell (2) is positioned in this gap and exposed to isotropic pressurization.

[0008] Therefore, when isotropic pressure is applied using this jig (1), as shown in FIG. 2, severe deformation occurs in the sealing part (2b) exposed to pressure, and consequently, there was a problem in that warping also occurred in the cup part.

[0009] [Prior Art Literature]

[0010] [Patent Literature]

[0011] Republic of Korea Published Patent No. 10-2024-0012798

[0012]

[0013] The present invention has been devised to resolve the above-mentioned problems of the prior art, and

[0014] The purpose is to provide a jig for isotropic pressing of a pouch cell and a method for isotropic pressing of a pouch cell using the same, which can significantly reduce deformation of the sealing portion and the resulting twisting of the pouch cup portion during isotropic pressing of the pouch cell.

[0015]

[0016] To achieve the above objective, the present invention

[0017] A lower plate having an opening in the center into which a cup portion of a pouch cell can be inserted, and an upper surface that supports a sealing portion of a pouch cell from below; and

[0018] The upper plate is coupled to the upper surface of the lower plate and includes an opening that overlaps the opening of the lower plate in an upward direction and a lower surface that presses the sealing portion of the pouch cell from above; and

[0019] The openings of the upper plate and the lower plate each provide a pouch cell isotropic pressurizing jig having a lateral area that is 1% or more to 10% or less wider than the lateral area of ​​the pouch cell cup portion to be isotropically pressurized.

[0020] In one embodiment of the present invention, the openings of the upper plate and the lower plate may each have a transverse area that is 1% or more to 5% or less wider than the transverse area of ​​the pouch cell cup portion to be isotropically pressurized.

[0021] In one embodiment of the present invention, the inner wall surface forming the opening of the upper plate and the lower plate and the outer wall surface of the pouch cell cup portion may have a gap of up to 2 mm.

[0022] In one embodiment of the present invention, the pouch cell isotropic pressurizing jig further includes an elastic ring provided on the upper surface of the lower plate or the lower surface of the upper plate, and the lateral internal area enclosed and partitioned by the elastic ring may be equal to or larger than the lateral area of ​​the opening by 5% or less.

[0023] In one embodiment of the present invention, the jig for isotropically pressurizing a pouch cell can be used for isotropically pressurizing a pouch cell in which a cup portion is formed above and below, respectively, with the sealing portion as the center.

[0024]

[0025] The present invention also,

[0026] A method for isotropically pressurizing a pouch cell using the above-described pouch cell isotropically pressurizing jig,

[0027] a) a step of preparing a pouch cell isotropic pressurizing jig in which the openings of the upper plate and the lower plate each have a lateral area that is 1% or more to 10% or less wider than the lateral area of ​​the pouch cell cup portion to be isotropically pressurized;

[0028] b) a step of inserting the cup portion of a pouch cell to be isotropically pressed into the opening of the lower plate and positioning the pouch cell so that the sealing portion of the pouch cell is supported on the upper surface of the lower plate;

[0029] c) a step of joining the upper plate to the lower plate such that the opening overlaps at the top of the pouch cell; and

[0030] d) a step of applying pressure to an isotropic pressurizing jig containing the above pouch cell by hydraulic pressure; the present invention provides a method for isotropically pressurizing a pouch cell.

[0031] In one embodiment of the present invention, in step a), a jig for isotropically pressurizing a pouch cell may be prepared and used, wherein the openings of the upper plate and the lower plate each have a lateral area that is 1% or more to 5% or less wider than the lateral area of ​​the pouch cell cup portion to be isotropically pressurized.

[0032] In one embodiment of the present invention, in step a), an elastic ring is further provided on the upper surface of the lower plate or the lower surface of the upper plate, and a pouch cell isotropic pressurizing jig can be prepared and used in which the lateral internal area enclosed by the elastic ring is equal to or wider than the lateral area of ​​the opening by 5% or less.

[0033] In one embodiment of the present invention, the method may be characterized by not using a sealing film that seals an isotropic pressure jig in which a pouch cell is fixed.

[0034]

[0035] When using the pouch cell isotropic pressurization jig of the present invention, the gap between the pouch cup portion and the opening of the jig in which the pouch cup portion is received is minimized, and accordingly, deformation of the sealing portion and the resulting twisting of the pouch cup portion during isotropic pressurization are minimized.

[0036] In addition, according to the isotropic pressurization method of the pouch cell of the present invention, the gap between the pouch cup portion and the opening of the jig in which the pouch cup portion is received is minimized, so the deformation of the sealing portion and the resulting twisting of the pouch cup portion during isotropic pressurization are minimized.

[0037]

[0038] FIG. 1 is an exploded perspective view showing the form of a conventional jig for isotropic pressure of a pouch cell and the form of a pouch cell receiving using the same.

[0039] FIG. 2 is a plan view illustrating the receiving form of a pouch cell with respect to the jig and the state of the pouch cell isotropically pressurized using the same when a conventional jig for isotropic pressurizing a pouch cell is used.

[0040] FIG. 3 is a plan view showing one embodiment of a jig for isotropic pressure of a pouch cell according to the present invention, and

[0041] FIG. 4 is a plan view illustrating the receiving form of a pouch cell with respect to the jig and the state of the pouch cell isotropically pressurized using the same when the pouch cell isotropically pressurized jig of the present invention is used.

[0042] FIG. 5 is a plan view showing another embodiment of the pouch cell isotropic pressurization jig of the present invention, and

[0043] FIG. 6 is a plan view illustrating the shape of a conventional pouch cell isotropic pressurization jig corresponding to the pouch cell isotropic pressurization jig of FIG. 5, and

[0044] FIG. 7 is a perspective view (a) and a plan view (b) showing the usage form of the pouch cell isotropic pressurization jig of the present invention, and

[0045] FIG. 8 is a cross-sectional view illustrating one form of a bicell type pouch cell that isotropically pressurized using the pouch cell isotropic pressurization jig of the present invention.

[0046]

[0047] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein. Throughout the specification, similar parts are denoted by the same reference numerals.

[0048] When it is stated that one component is "connected, equipped, or installed" on another component, it should be understood that it may be directly connected or installed on that other component, or that there may be other components in between. Conversely, when it is stated that one component is "directly connected, equipped, or installed" on another component, it should be understood that there are no other components in between. Meanwhile, other expressions describing the relationships between components, such as "on top of" and "directly on top," "between" and "exactly between," or "adjacent to" and "directly adjacent to," should be interpreted in the same way.

[0049] The present invention will be described in detail below with reference to the drawings.

[0050] FIG. 3 is a plan view showing one embodiment of the pouch cell isotropic pressurization jig of the present invention, and FIG. 4 is a plan view showing the receiving form of the pouch cell for the pouch cell isotropic pressurization jig of the present invention and the state of the pouch cell isotropically pressurized using the jig when the pouch cell isotropic pressurization jig of the present invention is used.

[0051] As illustrated in FIGS. 3 and 4 above, the pouch cell isotropic pressurizing jig (100) of the present invention comprises: a lower plate (30) having an opening (22) in the center into which a cup portion (12) of a pouch cell can be inserted, and an upper surface that supports a sealing portion (14) of a pouch cell (10) from below; and

[0052] The upper plate (20) is coupled to the upper surface of the lower plate (30) and includes a lower surface that presses from above the opening (22) that overlaps the opening (32) of the lower plate (30) in an upward direction and the sealing portion (14) of the pouch cell.

[0053] The openings (22, 32) of the upper plate (20) and lower plate (30) each have a transverse area that is 1% or more to 10% or less wider than the transverse area of ​​the pouch cell (10) cup portion (12) to be isotropically pressurized.

[0054] In the above, if the transverse area of ​​the openings (22, 32) of the upper plate (20) and lower plate (30) is less than 1% of the transverse area of ​​the pouch cell (10) cup portion (12), it is not desirable because it may take a long time to insert the pouch cell into the isotropic pressure jig, and if it exceeds 10%, the area of ​​the sealing portion exposed to isotropic pressure becomes larger, and accordingly, deformation occurs in the sealing portion (14), and deformation such as twisting may also occur in the cup portion depending on the deformation of the sealing portion (14), so it is not desirable.

[0055] In one embodiment of the present invention, it may be more preferable that the openings (22, 32) of the upper plate (20) and the lower plate (30) each have a wider lateral area of ​​1% or more to 5% or less, 1% or more to 3% or less, or 1% or more to 2% or less than the lateral area of ​​the pouch cell (10) cup portion (12) to be isotropically pressurized.

[0056] In one embodiment of the present invention, the inner wall surface forming the opening of the upper plate (20) and the lower plate (30) and the outer wall surface of the pouch cell cup portion may have a gap of up to 2 mm or 1 mm.

[0057] In the present invention, the transverse area of ​​the opening is based on the area of ​​the opening formed on the lower surface in the case of the upper plate (20), and based on the area of ​​the opening formed on the upper surface in the case of the lower plate (30). In addition, the transverse area of ​​the pouch cell (10) cup portion (12) is based on the maximum area among the transverse areas of the cup portion.

[0058] FIGS. 1 and 2 show the shape of a conventional jig for isotropic pressure of a pouch cell and the result of isotropic pressure using the same. In the conventional jig (1) for isotropic pressure of a pouch cell, a relatively wide gap is formed between the cup portion (2a) and the opening of the pouch cell when the pouch cell (2) is contained therein, and the sealing portion (2b) of the pouch cell (2) is positioned in this gap and exposed to isotropic pressure. Therefore, when isotropic pressure is performed using such a jig (1), as shown in FIG. 2, severe deformation occurs in the sealing portion (2b) exposed to pressure, and consequently, deformation (twisting) also occurs in the cup portion.

[0059] The present invention is characterized by solving these problems of the prior art.

[0060] In one embodiment of the present invention, it may be preferable that the opening (22) of the upper plate (20) and the opening (32) of the lower plate (30) have the same transverse area. In the above, the overlap between the opening of the upper plate and the opening of the lower plate means that they overlap in the vertical direction at the respective upper and lower positions.

[0061] The pouch cell isotropic pressurization jig (100) of the present invention can be used for isotropic pressurization in which hydraulic pressure is applied simultaneously to both sides of the pouch cell (10) cup portion.

[0062] In one embodiment of the present invention, the shape of the upper plate (20) and the lower plate (30) is not particularly limited as long as they include the openings (22, 33) defined above. For example, a square prism shape or a shape in which a chamfer is performed on the square prism shape is generally used, but is not limited thereto, and any shape known in the art may be used.

[0063] The upper plate (20) and lower plate (30) may preferably be used to have the same shape.

[0064] The upper plate (20) and lower plate (30) may further be provided with a coupling means (40) for joining them. Any means known in the art may be used without limitation as the coupling means (40). For example, a nut may be provided on the upper plate (20) and a bolt may be provided on the lower plate (30). Specifically, the upper plate (20) may be provided with a hole and a nut through which a bolt provided on the lower plate (30) can pass. In this case, the upper plate (20) may be fitted and joined to the lower plate (30) so that a bolt provided on the lower plate (30) can pass through the hole provided on the upper plate (20), and the nut may be tightened to form the connection. The bolt-nut coupling means may be provided in the required number.

[0065]

[0066] In one embodiment of the present invention, the pouch cell isotropic pressurizing jig (100) further includes an elastic ring (50) provided on the upper surface of the lower plate (30) or the lower surface of the upper plate (20), and the lateral internal area enclosed by the elastic ring (50) may be equal to or larger than the lateral area of ​​the opening, or 5% or less, 3% or less, 2% or less, or 1% or less.

[0067] Additionally, the transverse internal area enclosed by the elastic ring (50) provided on the upper surface of the lower plate (30) or the lower surface of the upper plate (20) may each have a transverse area that is 1% or more to 10% or less larger than the transverse area of ​​the pouch cell (10) cup portion (12) to be isotropically pressurized.

[0068] In the above, if the transverse internal area enclosed by the elastic ring (50) is less than 1% of the transverse area of ​​the pouch cell (10) cup portion (12), it is not desirable because it may take a long time to insert the pouch cell into the isotropic pressure jig, and if it exceeds 10%, the area of ​​the sealing portion exposed to isotropic pressure becomes larger, and accordingly, deformation occurs in the sealing portion (14), and deformation such as twisting may occur in the cup portion depending on the deformation of the sealing portion (14), so it is not desirable.

[0069] In one embodiment of the present invention, the transverse internal area enclosed by the elastic ring (50) provided on the upper surface of the lower plate (30) or the lower surface of the upper plate (20) may more preferably have a transverse area that is 1% or more to 5% or less, 1% or more to 3% or less, or 1% or more to 2% or less than the transverse area of ​​the pouch cell (10) cup portion (12) to be isotropically pressurized.

[0070] In one embodiment of the present invention, the elastic rings (50) provided on the lower surface of the upper plate (20) and the upper surface of the lower plate (30) may each be provided in a form that overlaps in a vertical direction from each other, and may have the same area.

[0071] The elastic ring (50) may be fixed, for example, by being inserted into a groove (not shown) for fixing the elastic ring (50) provided on the upper surface of the lower plate (30) or the lower surface of the upper plate (20). However, it is not limited thereto, and it is also possible to fix it by a method known in the art.

[0072] The elastic ring (50) performs the function of allowing the pouch cell (10) to be fixed to the jig (100) without damaging the sealing portion (14). However, as shown in FIG. 6, if a large gap is formed between the elastic ring (50) and the cup portion (12) of the pouch, a large area of ​​the sealing portion (14) may be exposed to isotropic pressure, and accordingly, deformation such as twisting may occur in the sealing portion (14), and such deformation may also affect the deformation of the cup portion.

[0073] Therefore, the pouch cell isotropic pressurization jig of the present invention has a structural feature of installing the elastic ring (50) as close as possible to the opening, as shown in FIG. 5.

[0074]

[0075] In one embodiment of the present invention, the pouch cell isotropic pressurizing jig (100) can be used for isotropic pressurizing a pouch cell (10) in which the cup portion (12) is formed only in one direction of the pouch cell with respect to the sealing portion (14), and a pouch cell (10) in which the cup portion (12) is formed in both directions of the pouch cell with respect to the sealing portion (14), as shown in FIG. 8.

[0076] In one embodiment of the present invention, the pouch cell (10) may be a mono-cell in which a cathode, a solid electrolyte, and an anode are sequentially stacked, with a conventional pouch covering it. Alternatively, the pouch cell (10) may be a bi-cell in which a solid electrolyte and an anode are sequentially stacked on both sides of a cathode, as shown in FIG. 8, with a conventional pouch covering it. Furthermore, the pouch cell (10) may include a structure greater than that of a bi-cell. Additionally, the pouch cell (10) may be a cell in which the electrodes and electrolyte are stacked in a structure different from the above. The cathode and the anode may be in a form including an active material layer and a current collector, and may also be freestanding electrodes that do not require a separate current collector.

[0077] The height (or depth) of the openings (22, 32) of the upper plate (20) and lower plate (30) may be, for example, the same as or higher than the height of the cup portion (12) of the pouch cell (10).

[0078] The upper plate (20) and lower plate (30) may be manufactured from materials such as steel or ceramic, for example, but are not limited thereto. The upper plate (20) and lower plate (30) may be made of the same material or may be made of different materials.

[0079]

[0080] Although the pouch cell isotropic pressurization jig (100) of the present invention has been described above focusing on essential components, descriptions of components generally used in this field have been omitted. However, it should be understood that the pouch cell isotropic pressurization jig (100) of the present invention may include, without limitation, additional components or devices known in this field, in addition to the components or devices described above.

[0081]

[0082] The present invention also,

[0083] A method of isotropically pressurizing a pouch cell (10) using the above-mentioned pouch cell isotropically pressurizing jig (100),

[0084] a) a step of preparing a pouch cell isotropic pressurizing jig (100) having a lateral area that is 1% or more to 10% or less wider than the lateral area of ​​the pouch cell (10) cup portion (12) to be isotropically pressurized, wherein the openings of the upper plate (20) and the lower plate (20) are each isotropically pressurized;

[0085] b) a step of inserting the cup portion (12) of the pouch cell (10) to be isotropically pressed into the opening (32) of the lower plate (30) and positioning the pouch cell (10) so that the sealing portion (14) of the pouch cell is supported on the upper surface of the lower plate (30);

[0086] c) a step of joining the upper plate (20) to the lower plate (30) such that the opening (22) overlaps at the upper part of the pouch cell (10); and

[0087] d) a step of applying pressure by hydraulic pressure to an isotropic pressurizing jig (100) containing the above pouch cell (10); the present invention provides a method for isotropically pressurizing a pouch cell, comprising: a step of applying pressure by hydraulic pressure to an isotropic pressurizing jig (100) containing the above pouch cell (10).

[0088] All the details regarding the isotropic pressurization jig for the pouch cell described above can be applied identically to the isotropic pressurization method of the pouch cell mentioned above. Therefore, explanations regarding redundant content are omitted.

[0089] In one embodiment of the present invention, in step a), it may be more preferable to prepare and use a pouch cell isotropic pressurizing jig in which the openings (22, 32) of the upper plate (20) and the lower plate (30) each have a lateral area that is 1% or more to 5% or less wider than the lateral area of ​​the pouch cell (10) cup portion (12) to be isotropically pressurized.

[0090] In one embodiment of the present invention, in step a), a pouch cell isotropic pressurizing jig may be prepared and used, in which the inner wall surface forming the opening of the upper plate (20) and the lower plate (30) and the outer wall surface of the pouch cell cup portion have a gap of up to 2 mm.

[0091] In one embodiment of the present invention, in step a), an elastic ring (50) is further provided on the upper surface of the lower plate (30) or the lower surface of the upper plate (20), and a pouch cell isotropic pressurizing jig (100) can be prepared and used, wherein the lateral internal area enclosed by the elastic ring (50) is the same as or 5% or less wider than the lateral area of ​​the opening.

[0092]

[0093] In one embodiment of the present invention, the method may be characterized by not using a sealing film that seals an isotropic pressure jig in which a pouch cell is fixed.

[0094] In the present invention, the isostatic pressing can be performed as any one of warm isostatic pressing (WIP), hot isostatic pressing (HIP), and cold isostatic pressing (CIP). These isostatic pressings can be performed under pressure where good interfacial contact is achieved between the solid electrolyte and the electrode. Additionally, they can be performed under a temperature within an appropriate range where the electrode constituent material is thermally stable. For example, the warm isostatic pressing (WIP) can be performed at 45 to 100°C.

[0095]

[0096] Although the present invention has been described in relation to the preferred embodiments mentioned above, various modifications and variations are possible without departing from the essence and scope of the invention. Accordingly, the appended claims will include such modifications and variations insofar as they fall within the essence of the invention.

[0097] [Explanation of the symbol]

[0098] 10: Pouch cell 12: Pouch cup

[0099] 14: Pouch sealing part 20: Upper plate

[0100] 22: Opening 30: Lower plate

[0101] 32: Opening, 40: Connecting means

[0102] 50: Elastic ring 100: Jig for isotropic pressure of pouch cell

Claims

1. A lower plate having an opening in the center into which the cup portion of the pouch cell can be inserted, and an upper surface that supports the sealing portion of the pouch cell from below; and The upper plate is coupled to the upper surface of the lower plate and includes an opening that overlaps the opening of the lower plate in an upward direction and a lower surface that presses the sealing portion of the pouch cell from above; and A pouch cell isotropic pressurizing jig in which the openings of the upper plate and the lower plate each have a lateral area that is 1% or more to 10% or less wider than the lateral area of ​​the pouch cell cup portion to be isotropically pressurized.

2. In Paragraph 1, A jig for isotropically pressurizing a pouch cell, characterized in that the openings of the upper plate and the lower plate each have a lateral area that is 1% or more to 5% or less wider than the lateral area of ​​the pouch cell cup portion to be isotropically pressurized.

3. In Paragraph 1, A jig for isotropically pressurizing a pouch cell, characterized in that the inner wall surface forming the opening of the upper plate and the lower plate and the outer wall surface of the pouch cell cup portion have a gap of up to 2 mm.

4. In Paragraph 1, It further includes an elastic ring provided on the upper surface of the lower plate or the lower surface of the upper plate, and A pouch cell isotropic pressurizing jig characterized in that the lateral internal area partitioned by the elastic ring is equal to or wider than the lateral area of ​​the opening by 5% or less.

5. In Paragraph 1, The above jig is a pouch cell isotropic pressurizing jig characterized by being used for isotropic pressurizing a pouch cell in which cup portions are formed above and below, respectively, centered on a sealing portion.

6. A method of isotropically pressurizing a pouch cell using the jig of claim 1, a) a step of preparing a pouch cell isotropic pressurizing jig in which the openings of the upper plate and the lower plate each have a lateral area that is 1% or more to 10% or less wider than the lateral area of ​​the pouch cell cup portion to be isotropically pressurized; b) a step of inserting the cup portion of a pouch cell to be isotropically pressed into the opening of the lower plate and positioning the pouch cell so that the sealing portion of the pouch cell is supported on the upper surface of the lower plate; c) a step of joining the upper plate to the upper surface of the lower plate such that the openings overlap; and d) a step of applying pressure by hydraulic pressure to an isotropic pressurizing jig containing the pouch cell; a method for isotropically pressurizing a pouch cell.

7. In Paragraph 6, A method for isotropically pressurizing a pouch cell, characterized by preparing a jig for isotropically pressurizing a pouch cell, wherein the openings of the upper plate and the lower plate in step a) above each have a transverse area that is 1% or more to 5% or less wider than the transverse area of ​​the pouch cell cup portion to be isotropically pressurized.

8. In Paragraph 6, A method for isotropically pressurizing a pouch cell, characterized by preparing a jig for isotropically pressurizing a pouch cell in step a), wherein an elastic ring is further provided on the upper surface of the lower plate or the lower surface of the upper plate, and the lateral internal area enclosed and partitioned by the elastic ring is equal to or wider than the lateral area of ​​the opening by 5% or less.

9. In Paragraph 6, The above method is an isotropic pressure method for a pouch cell characterized by not using a sealing film that seals by housing an isotropic pressure jig fixed to the pouch cell inside.

Images