Battery case forming apparatus and battery case forming method using the same

Abstract

The present invention relates to a battery casing forming device, comprising: a punch configured to press a laminate to form a battery casing; a mold having a receiving portion formed therein, the receiving portion having a size corresponding to an electrode assembly accommodating portion formed by the punch; a retaining member configured to fix the outer periphery of the laminate; and an elastic partition located below the punch to prevent direct contact between the punch and the laminate, wherein a stretching area of ​​the laminate is extended to prevent the laminate from being locally overstretched.

Description

Technical Field

[0001] This application claims the benefit of priority from Korean Patent Application No. 2020-0137864, filed on October 22, 2020, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a battery case forming apparatus and a battery case forming method using the same. More specifically, the present invention relates to a battery case forming apparatus including a punch configured to form a battery case for a pouch-shaped battery, and a battery case forming method using the same. The battery case forming apparatus further includes an elastic spacer that minimizes damage to the surface of a laminated sheet serving as the battery case when the punch presses the laminated sheet. Background Art

[0003] The demand for secondary batteries as energy sources for mobile devices and electric vehicles is rapidly increasing. In particular, the demand for lithium secondary batteries with high energy density and high discharge voltage is high.

[0004] Based on their shape and material, lithium secondary batteries can be divided into cylindrical secondary batteries made of metal materials, prismatic secondary batteries made of metal materials, or pouch-shaped secondary batteries made of laminated sheets. The advantages of pouch-shaped secondary batteries are that they can be stacked with a high degree of integration, resulting in a high energy density per unit weight, low manufacturing cost, and easy deformation. As a result, pouch-shaped secondary batteries are used in various devices.

[0005] The pouch-shaped secondary battery uses a laminate sheet including an outer coating layer, a metal barrier layer, and an inner adhesive layer as a battery case and is configured to have a structure in which an electrode assembly is accommodated together with an electrolyte in a receiving portion formed in the laminate sheet.

[0006] To form the electrode assembly housing in pouch-shaped secondary batteries, a deep-drawing method is used. This involves placing a laminate sheet on a mold, securing it with a jig, and pressing it with a punch. However, during the deep-drawing process, external defects such as pinholes or cracks are formed on the outer surface of the laminate sheet due to the limited softness of the laminate sheet and the friction between the punch and the laminate sheet.

[0007] Even if the surface roughness of the punch contacting the laminate is extremely reduced to prevent the formation of such external defects, it is difficult to prevent the formation of external defects on the laminate due to the friction caused by repeated punching. In particular, when the thickness of the laminate, especially the thickness of the metal barrier layer, is small, the formability of the laminate is reduced, making it more likely to form pinholes or cracks. For this reason, it is difficult to form the electrode assembly receiving portion to have a large depth, making it difficult to manufacture high-capacity lithium secondary batteries.

[0008] Patent Document 1 discloses an outer casing member for a battery including an outer layer comprising a heat-resistant resin film, a metal foil layer, and an inner layer comprising a thermoplastic resin film to which a lubricant is added, wherein the lubricant is attached between the outer layer and the inner layer.

[0009] In Patent Document 1, a lubricant is attached between the outer layer and the inner layer, thereby improving the sliding properties of the outer layer relative to the second mold and the inner layer relative to the first mold, thereby suppressing the warping of the outer peripheral portion of the battery casing member.

[0010] Patent document 2 discloses a packaging material for molding, which includes a base layer as an outer layer, a heat-fusible resin layer as an inner layer, and a metal foil layer provided between the two layers, wherein the heat-fusible resin layer is configured to have a single-layer structure or a multi-layer structure, and the innermost layer of the heat-fusible resin layer is made of a resin composition containing an anti-blocking agent, a slip agent, and a fluoropolymer-based lubricant.

[0011] In Patent Document 2, when the encapsulating material is molded, the sliding property between the surface of the innermost layer of the heat-fusible resin layer and the surface of the molding die is improved, so that the moldability can be improved.

[0012] Patent Documents 1 and 2 do not recognize the problem of defects occurring due to stretching of the outer casing member for a battery during the drawing process, and do not propose a method for solving this problem.

[0013] Therefore, there is a high demand for a technology that can prevent damage to the appearance of a laminated sheet and improve formability during the process of forming a laminated sheet.

[0014] Japanese Patent Publication No. 5959205 (July 7, 2016) "Patent Document 1"

[0015] Korean Patent Application Publication No. 2020-0027987 (March 13, 2020) "Patent Document 2" Summary of the Invention

[0016] Technical issues

[0017] The present invention has been made in view of the above problems, and its purpose is to provide a battery shell forming device and a battery shell forming method using the battery shell forming device, which can reduce the friction between the punch and the laminate sheet caused by the contact between the punch configured to press the laminate sheet to form the battery shell, thereby preventing damage to the laminate sheet.

[0018] Technical Solution

[0019] In order to achieve the above-mentioned purpose, the battery case forming equipment according to the present invention includes: a punch, which is configured to press a laminate to form a battery case; a mold, in which a receiving portion is formed, and the receiving portion has a size corresponding to the electrode assembly accommodating portion formed by the punch; a retaining member, which is configured to fix the outer periphery of the laminate; and an elastic partition, which is located below the punch so as to prevent direct contact between the punch and the laminate.

[0020] In the battery case forming apparatus according to the present invention, the elastic spacer may be fixed to the holder.

[0021] In the battery case forming apparatus according to the present invention, the elastic spacer may be fixed to a lower portion of a side surface of the holder.

[0022] In the battery case forming apparatus according to the present invention, before the battery case is formed by the punch, a lower surface of the punch may be parallel to an upper surface of the elastic spacer.

[0023] In the battery case forming apparatus according to the present invention, a liquid lubricant may be added to a space formed by the elastic spacer and the retainer.

[0024] In the battery case forming apparatus according to the present invention, a recess may be formed in at least a portion of a lower surface of the punch.

[0025] In the battery case forming apparatus according to the present invention, a gasket may be provided at a lower portion of the receiving portion of the mold.

[0026] In the battery case forming apparatus according to the present invention, the gasket may be made of an elastic material and may be configured such that a central portion of the gasket protrudes convexly.

[0027] In the battery case forming apparatus according to the present invention, due to the pressing of the punch, the protruding central portion of the gasket may be compressed, so that the entire thickness of the gasket may become uniform.

[0028] In the battery case forming apparatus according to the present invention, the elastic spacer may be a watertight elastic spacer.

[0029] The present invention provides a battery case forming method using the battery case forming apparatus.

[0030] Specifically, the battery case forming method may include the following steps: (a) placing a laminate sheet on the mold; (b) fixing the laminate sheet to the mold using a retaining member to which an elastic partition is attached; and (c) pressing the elastic partition and the laminate sheet using the punch.

[0031] The battery case forming method according to the present invention may further include adding a liquid lubricant to a space formed by the elastic spacer and the retainer between steps (b) and (c).

[0032] In the battery case forming method according to the present invention, in the step (c), pressing may be performed until a gasket provided at a lower portion of the receiving portion of the mold is compressed and flattened.

[0033] In the battery case forming method according to the present invention, when the gasket starts to be compressed, the liquid lubricant may move to the edge of the lower surface of the punch.

[0034] In the battery case forming method according to the present invention, the region of the laminate sheet stretched by pressing in step (c) may be a side surface of the electrode assembly receiving portion and an outer peripheral portion of the bottom of the electrode assembly receiving portion.

[0035] Furthermore, the present invention provides a battery case manufactured using the battery case forming apparatus, wherein a thickness of a minimum thickness portion of the battery case is 70% or more of a thickness of a maximum thickness portion of the battery case.

[0036] Beneficial effects

[0037] It is obvious from the above description that in the present invention, the electrode assembly accommodating portion is formed with an elastic partition inserted between the laminate and the punch, thereby preventing direct contact between the punch and the laminate, and thus minimizing the stick-slip effect occurring on the surface of the punch and the surface of the laminate.

[0038] Furthermore, a liquid lubricant is added to reduce the friction between the punch and the laminate.

[0039] Furthermore, due to the addition of the liquid lubricant and the elastic spacer, the stretched region of the laminate can be extended, thereby preventing the laminate from being locally overstretched and thinned.

[0040] As described above, friction during a manufacturing process may be reduced and the thickness of the sidewall of the electrode assembly receiving part of the battery case may be prevented from being excessively reduced locally, thereby preventing pinholes or cracks from being formed on the battery case.

[0041] Furthermore, when using the battery case forming apparatus and method according to the present invention, the electrode assembly accommodating part can be formed deeper even with a laminate sheet having the same thickness, thereby increasing the capacity of the battery cell and improving the energy density of the battery cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 is a sectional view of a battery case forming apparatus according to a first embodiment of the present invention.

[0043] Figure 2 is an exploded perspective view of a battery case forming apparatus according to a first embodiment of the present invention.

[0044] Figure 3 is a sectional view of a battery case forming apparatus according to a second embodiment of the present invention.

[0045] Figure 4 is a sectional view of a battery case forming apparatus according to a third embodiment of the present invention.

[0046] Figure 5 is an exploded perspective view of a battery case forming apparatus according to a third embodiment of the present invention.

[0047] Figure 6 is a vertical sectional view of a battery case manufactured using the battery case forming apparatus according to the present invention.

[0048] Figure 7 is a vertical cross-sectional view of the central portion of the punch according to the present invention.

[0049] Figure 8 The manufacturing process of the battery case according to the present invention is shown sequentially. DETAILED DESCRIPTION

[0050] Now, the preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily implement the preferred embodiments of the present invention. However, in describing the working principles of the preferred embodiments of the present invention in detail, when the detailed description of known functions and structures incorporated herein may obscure the main purpose of the present invention, the detailed description will be omitted.

[0051] In addition, the same reference numerals will be used throughout the drawings to represent components that perform similar functions or operations. Where a component is referred to as being connected to another component throughout the application, the component may be directly connected to the other component and may also be indirectly connected to the other component via another component. In addition, the inclusion of an element does not mean the exclusion of other elements, but rather means that other elements may be further included unless otherwise specified.

[0052] Furthermore, unless otherwise limited, the description that specifies elements by limitation or addition is applicable to all inventions and does not limit the specific invention.

[0053] Furthermore, in the description of the present invention and the claims of this application, unless otherwise mentioned, the singular form is intended to include the plural form.

[0054] In addition, in the description of the present invention and the claims of this application, unless otherwise stated, "or" includes "and". Therefore, "including A or B" refers to three cases, namely, the case including A, the case including B, and the case including A and B.

[0055] Embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0056] Figure 1 is a sectional view of a battery case forming apparatus according to a first embodiment of the present invention, Figure 2 is an exploded perspective view of a battery case forming apparatus according to a first embodiment of the present invention.

[0057] Reference Figure 1 and Figure 2 The battery case forming apparatus 100 includes: a punch 110 configured to press a laminate 101 to form a battery case; a mold 120 in which a receiving portion 121 is formed, the receiving portion 121 having a size corresponding to an electrode assembly accommodating portion formed by the punch; a retainer 130 configured to fix the periphery of the laminate 101; and an elastic partition 140 located below the punch 110 so as to prevent direct contact between the punch 110 and the laminate 101.

[0058] In order to manufacture a pouch-shaped battery case using a laminate sheet, the laminate sheet 101 is set on a mold 120 having a receiving portion 121 having a size corresponding to the electrode assembly receiving portion, the outer periphery of the laminate sheet 101 is fixed to the mold using a retainer 130, and the laminate sheet 101 is pressed by a punch 110, so that the electrode assembly receiving portion can be formed.

[0059] At this time, in order to prevent direct contact between the laminated sheet and the punch, an elastic spacer 140 is provided between the laminated sheet and the punch.

[0060] When the laminate and the punch are in direct contact, slippage is less likely to occur due to friction between the surface of the laminate and the surface of the punch. As a result, the stretched area of ​​the laminate narrows, so only a local area of ​​the laminate is stretched. Specifically, because the portion of the laminate that becomes the sidewall of the electrode assembly receiving portion when the laminate is formed into a battery case is mainly stretched, the thickness of this portion is excessively reduced, and the battery case is easily damaged.

[0061] As described above, since a stick-slip phenomenon easily occurs on the surface of the laminate sheet and the surface of the punch, the laminate sheet may be locally overstretched, and thus a battery case forming defect rate may increase.

[0062] In the present invention, the laminate 101 is pressed by the punch 110 while an elastic spacer 140 is provided between the laminate 101 and the punch 110. Therefore, the surface of the laminate and the surface of the punch do not directly contact each other. Thus, the conventional problem of scratching the laminate due to the uneven surface of the punch or foreign matter entering between the punch and the laminate can be solved.

[0063] The x-axis width w1 of the punch 110 may be smaller than the x-axis distance w2 between opposite sides of the die, and the x-axis distance w2 between opposite sides of the die may be smaller than the x-axis distance w3 between opposite sides of the holder.

[0064] Thus, the punch can easily enter the die via the holder.

[0065] Figure 3 is a sectional view of a battery case forming apparatus according to a second embodiment of the present invention.

[0066] Reference Figure 3 The battery case forming apparatus 200 includes a punch 210 configured to press a laminate 201 to form a battery case; a mold 220 having a receiving portion 221 formed therein, the receiving portion 221 having a size corresponding to the electrode assembly receiving portion formed by the punch; a retainer 230 configured to fix the outer periphery of the laminate 201; and an elastic diaphragm 240 located below the punch 210 to prevent direct contact between the punch 210 and the laminate 201. The elastic diaphragm 240 is fixed to the retainer 230. The retainer 230, to which the elastic diaphragm 240 is fixed, is disposed on the laminate 201, thereby fixing the laminate.

[0067] As described above, since the elastic spacer 240 is fixed to the holder 230 , a state in which the elastic spacer 240 is fixed to the holder can be stably maintained when the laminated sheet 201 is pressed by the punch 210 .

[0068] For example, the elastic diaphragm 240 may be attached to the lower surface of the retainer 230, or may be fixed to the lower portion of the side surface of the retainer 230. When the elastic diaphragm 240 is attached to the lower surface of the retainer 230, the fixing force of the laminate 201 can be further increased by the subtle protrusions formed by the combination of the elastic diaphragm 240 and the retainer 230. When the elastic diaphragm 240 is fixed to the lower portion of the side surface of the retainer 230, particularly when the elastic diaphragm 240 is inserted into and fixed to the recess formed in the lower portion of the side surface of the retainer 230, the bonding force between the elastic diaphragm 240 and the retainer 230 can be further increased. As a result, the bonding between the elastic diaphragm 240 and the retainer can be maintained even when the elastic diaphragm 240 is overstretched. A more beneficial effect can be achieved when the depth of the accommodating portion is greater.

[0069] Before the punch is used to form the battery case, the lower surface of the punch is positioned parallel to the upper surface of the elastic separator 240. Furthermore, the elastic separator and the laminate are positioned parallel to each other. Therefore, when the punch is used to press the elastic separator, the entire area of ​​the punch can apply uniform pressure to the entire area of ​​the elastic separator and the laminate.

[0070] In the present application, the force generated by the punch is applied to the elastic diaphragm and the laminate with the same magnitude and in the same direction, and the deformation of the laminate is the same as that of the elastic diaphragm.

[0071] Figure 4 is a sectional view of a battery case forming apparatus according to a third embodiment of the present invention, Figure 5 is an exploded perspective view of a battery case forming apparatus according to a third embodiment of the present invention.

[0072] Reference Figure 4 and Figure 5 The battery case forming equipment 300 includes: a punch 310, the punch 310 is configured to press the laminate 301 to form the battery case; a mold 320, a receiving portion 321 is formed in the mold 320, and the receiving portion 321 has a size corresponding to the electrode assembly accommodating portion formed by the punch; a retainer 330, the retainer 330 is configured to fix the outer periphery of the laminate 301; and an elastic partition 340, the elastic partition 340 is located below the punch 310 to prevent direct contact between the punch 310 and the laminate 301.

[0073] Elastic diaphragm 340 is fixed to retainer 330. As a result, a space is formed with the elastic diaphragm as the lower surface and the inner surface of retainer 330 as the side wall, and liquid lubricant 350 is added to this space. Since the elastic diaphragm is a watertight elastic diaphragm, the liquid lubricant cannot be discharged through the elastic diaphragm and can only move within the space.

[0074] The liquid lubricant significantly reduces the friction between the punch and the elastic diaphragm, so that the surface of the elastic diaphragm and the surface of the punch can slide very smoothly relative to each other.

[0075] As a result, the area of ​​the laminate stretched by the punch increases, and thus the average elongation of the stretched area can be reduced. For example, the thickness of the laminate in the stretched state can be about 70% or more of the thickness of the laminate before stretching.

[0076] For example, as the liquid lubricant, at least one selected from the group consisting of hydrocarbon-based oils such as liquid paraffin, greases, mineral vegetable oils, emulsified oils, anti-emulsifiers, pour point depressants, viscosity modifiers, defoaming agents, mineral oils including pure mineral oils or pure mineral oils containing additives, fatty oils including animal oils and vegetable oils, mixed oils of mineral oils and fatty oils, and synthetic oils can be used.

[0077] In the case where the liquid lubricant is used as described above, it is possible to prevent a local area of ​​the laminate from being excessively stretched.

[0078] Figure 6 : is a vertical cross-sectional view of a battery case manufactured using the battery case forming apparatus according to the present invention. Figure 6 An electrode assembly receiving portion 410 is concavely formed in the battery case 400. The electrode assembly receiving portion 410 may be composed of a bottom portion 411 of the electrode assembly receiving portion and a side surface 412 of the electrode assembly receiving portion.

[0079] Unlike the present invention, if a liquid lubricant is not used, the laminate is stretched only in the main stretching region E1. As a result, the average elongation in the main stretching region is high, so that the region becomes weak, and the battery case can be easily damaged.

[0080] However, since a liquid lubricant is used in the present invention, good sliding occurs between the surface of the punch and the surface of the elastic separator. Thus, in addition to the main stretching region E1, the stretching region also extends to the additional stretching region E2. That is, the stretched region of the laminate can be the side surface 412 of the electrode assembly receiving portion and the outer peripheral portion of the bottom 411 of the electrode assembly receiving portion.

[0081] As described above, since the stretched region extends, the average elongation is reduced, so that the thickness reduction rate of the battery case can be reduced even after the battery case is formed, and the battery case can be prevented from being locally weakened.

[0082] In the battery case manufactured using the battery case manufacturing apparatus according to the present invention, the thickness of the minimum thickness portion of the battery case may be 70% or more of the thickness of the maximum thickness portion of the battery case.

[0083] Return to reference Figure 4 and Figure 5 A gasket 360 is provided at the lowermost portion of the receiving portion 321 of the mold 320 .

[0084] The liner 360 may be made of an elastic material so as to be compressed by the punch 310. The liner 360 may be formed into a quadrilateral shape when viewed in a plane, and may be configured to have a structure in which the central portion of the liner protrudes convexly and the thickness of the liner gradually decreases toward its peripheral portion. When the laminate is pressed by the punch 310 to form, the protruding central portion of the liner first contacts the laminate moved downward by the punch. Subsequently, when the laminate is continuously pressed downward by the punch, the protruding central portion of the liner is compressed, so that the entire thickness of the liner becomes uniform. As a result, the bottom of the electrode assembly accommodating portion can be flattened.

[0085] Furthermore, since the elastic pad 360 is provided, the exterior of the lower surface of the laminated sheet can be prevented from being scratched.

[0086] Figure 7 is a vertical cross-sectional view of the central portion of the punch according to the present invention.

[0087] Reference Figure 7 , a recess 411 or 511 is formed in the lower surface of the punch 410 or 510 .

[0088] The recess 411 formed in the punch 410 is configured such that a central portion of the lower surface of the punch is recessed, and the recess 511 formed in the punch 510 is configured such that the entire lower surface of the punch is recessed.

[0089] As a result of the recess formed as described above, a space is formed in the lower surface of the punch. When the elastic partition and the laminate are pressed by the punch, a portion of the liquid lubricant gathers in the recess and the remaining liquid lubricant moves to the edge of the lower surface of the punch.

[0090] The friction between the central portion of the punch and the elastic diaphragm is reduced by the liquid lubricant collected in the recess.

[0091] Figure 8 The battery case forming method according to the present invention is shown from left to right and from top to bottom.

[0092] The battery case forming method according to the present invention includes the steps of: setting a laminate sheet 301 on a mold 320 ; fixing the laminate sheet 301 to the mold 320 using a holder 330 to which an elastic spacer 340 is attached; and pressing the elastic spacer 340 and the laminate sheet 301 using a punch 310 .

[0093] After the laminate 301 is fixed to the die 320 and before the laminate 301 is pressed by the punch 310, a liquid lubricant 350 is added to the space formed by the elastic diaphragm 340 and the retainer 330. Since the elastic diaphragm according to the present invention is a watertight elastic diaphragm, the liquid lubricant is not discharged to the outside of the elastic diaphragm.

[0094] In the step of pressing the laminate 310 using the punch 310, the pressing is performed until the liner 360 provided at the lower portion of the receiving portion of the die 320 is compressed and flattened. Since the liner 360 is configured to have a structure in which the central portion of the liner protrudes and the thickness of the liner gradually decreases toward the peripheral portion thereof, the laminate 301 first comes into contact with the protruding central portion of the liner 360.

[0095] When the gasket 360 begins to compress, the central portion of the gasket 360 contacts the laminate 301, but a space is formed between the outer peripheral portion of the gasket 360 and the laminate 301. As a result of the pressing, the liquid lubricant 350 on the elastic diaphragm 340 moves toward the space formed between the laminate 301 and the outer peripheral portion of the gasket 360, that is, moves to the edge of the lower surface of the punch 310.

[0096] In the case where a recess is formed in the lower surface of the punch 310 , a portion of the liquid lubricant may be collected in the recess, and thus friction between the punch and the elastic spacer at the lower surface of the punch may be reduced.

[0097] As the punch 310 is inserted into the receiving portion of the die 320, the liquid lubricant 350 moves to the edge of the lower surface of the punch 310 and eventually moves along the side surface of the punch 310. As a result, the liquid lubricant 350 can exist not only between the lower surface of the punch 310 and the surface of the elastic diaphragm 340, but also between the side surface of the punch 310 and the surface of the elastic diaphragm 340, thereby reducing the friction between the punch and the elastic diaphragm. As the pressing progresses, the liquid lubricant 350 spreads more widely due to capillary action.

[0098] As described above, in the present invention, a gasket with a protruding central portion is provided at the lower portion of the receiving portion of the mold, thereby facilitating the movement of the liquid lubricant to the primary and additional stretching zones of the laminate. This minimizes friction between the surface of the elastic separator and the surface of the punch, ensuring a wide additional stretching zone for the laminate, and thus enabling the manufacture of a battery casing with minimal localized thickness reduction.

[0099] Those skilled in the art to which the present invention pertains will appreciate that various applications and modifications are possible within the scope of the present invention based on the above description.

[0100] (Explanation of Reference Numbers)

[0101] 100, 200, 300: Battery casing forming equipment

[0102] 101, 201, 301: Laminated sheets

[0103] 110, 210, 310, 410, 510,: punch

[0104] 120, 220, 320: mold

[0105] 121, 221, 321: Reception Department

[0106] 130, 230, 330: retaining parts

[0107] 140, 240, 340: elastic partition

[0108] 411, 511: concave part

[0109] 350: Liquid lubricant

[0110] 360: Padding

[0111] 400: Battery housing

[0112] 410: Electrode assembly accommodating portion

[0113] 411: Bottom of the electrode assembly receiving portion

[0114] 412: Side surface of the electrode assembly receiving portion

[0115] E1: Main stretching area

[0116] E2: Additional stretch area.

[0117] Industrial Applicability

[0118] The present invention relates to a battery case forming device and a battery case forming method using the same, wherein the battery case forming device includes a punch configured to form a battery case for a pouch-shaped battery, wherein the battery case forming device further includes an elastic partition, which can minimize damage to the surface of the laminate when the laminate used as the battery case is pressed by the punch, so that the present invention has industrial applicability.

Claims

1. A battery casing forming device comprising: a punch configured to press the laminate to form a battery case; a mold having a receiving portion formed therein, the receiving portion having a size corresponding to the electrode assembly receiving portion formed by the punch; a retainer configured to secure an outer periphery of the laminate; and an elastic diaphragm located below the punch so as to prevent direct contact between the punch and the laminate, wherein the elastic diaphragm is fixed to the retaining member. 2 . The battery case forming apparatus according to claim 1 , wherein the elastic spacer is fixed to a lower portion of a side surface of the holder. 3 . The battery case forming apparatus according to claim 1 , wherein before the battery case is formed by the punch, a lower surface of the punch is parallel to an upper surface of the elastic spacer. 4 . The battery case forming apparatus according to claim 1 , wherein a liquid lubricant is added in a space formed by the elastic spacer and the retaining member. 5 . The battery case forming apparatus according to claim 1 , wherein a recess is formed in at least a portion of a lower surface of the punch. The battery case forming apparatus according to claim 1 , wherein a gasket is provided at a lower portion of the receiving portion of the mold. 7 . The battery case forming apparatus according to claim 6 , wherein the gasket is made of an elastic material and is configured such that a central portion of the gasket protrudes convexly. 8 . The battery case forming apparatus according to claim 7 , wherein the protruding central portion of the gasket is compressed due to the pressing of the punch, so that the entire thickness of the gasket becomes uniform. 9 . The battery case forming apparatus according to claim 1 , wherein the elastic spacer is a watertight elastic spacer.

10. A battery case forming method using the battery case forming apparatus according to any one of claims 1 to 9, the battery case forming method comprising the following steps: (a) placing a laminate on the mold; (b) securing the laminate to the mold using a retainer to which a resilient spacer is attached; and (c) Pressing the elastic spacer and the laminated sheet using the punch. 11 . The battery case forming method according to claim 10 , further comprising adding a liquid lubricant to a space formed by the elastic spacer and the retainer between steps (b) and (c).

12. The battery case forming method according to claim 11, wherein: In step (c), pressing is performed until a gasket provided at a lower portion of the receiving portion of the mold is compressed and flattened.

13. The battery case forming method according to claim 12, wherein: As the pad begins to compress, the liquid lubricant moves to the edge of the lower surface of the punch. 14 . The battery case forming method according to claim 10 , wherein the region of the laminate sheet stretched by pressing in step (c) is a side surface of the electrode assembly receiving portion and an outer peripheral portion of a bottom of the electrode assembly receiving portion. 15 . A battery case manufactured using the battery case forming apparatus according to claim 1 , wherein a thickness of a minimum thickness portion of the battery case is 70% or more of a thickness of a maximum thickness portion of the battery case.

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