Apparatus and method for molding a battery case and a battery case

Abstract

A device for molding a battery case according to one embodiment of the present application to solve the above problems includes a mold having a pouch film disposed on a top surface thereof and including at least one molding space recessed inward from the top surface, and a punch disposed above the molding space and lowered to insert the pouch film into the molding space and mold, wherein the top surface of the mold includes at least one mold slope.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2020-0129026, filed on October 6, 2020, and Korean Patent Application No. 10-2021-0131992, filed on October 5, 2021, both of which are incorporated herein by reference in their entirety. Technical Field

[0004] The present invention relates to an apparatus and method for molding a battery casing, and more specifically, to an apparatus and method for molding a battery casing in which, when a cup portion is formed by molding a soft film, the outer wall of the cup portion formed on one side of the fold portion integrally connected to the first casing to the second casing is molded to be nearly vertical. Background Technology

[0005] Typically, rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. These rechargeable batteries are suitable for use in small products (e.g., digital cameras, P-DVD players, MP3 players, mobile phones, PDAs, portable game consoles, power tools, electric bicycles, etc.) as well as in large products requiring high power (e.g., electric and hybrid vehicles, power storage devices for storing excess or renewable energy, and backup power storage devices).

[0006] Typically, to manufacture a secondary battery, an active electrode material slurry is first coated onto the positive and negative current collectors to create the positive and negative electrodes. The electrodes are then stacked on both sides of a separator to form an electrode assembly. Furthermore, the electrode assembly is housed in a battery casing, and the battery casing is sealed after electrolyte is injected into it.

[0007] These secondary batteries are classified into pouch-type and can-type secondary batteries based on the material of the casing that houses the electrode components. In pouch-type secondary batteries, the electrode components are housed in a pouch made of a flexible polymer material with variable shape.

[0008] The pouch cell, serving as the casing for a pouch-type secondary battery, is manufactured by stamping a flexible pouch film to form a cup. Furthermore, during cup formation, electrode assemblies are housed within the cup's containment space, and then the edges of the cup are sealed to manufacture the secondary battery.

[0009] In stamping, stretch forming is achieved by inserting the soft-pack film into a molding apparatus (e.g., a stamping machine) and stretching the film by applying pressure to it using a punch. However, due to the gap between the inner wall of the forming space of the mold and the outer wall of the punch, the outer wall of the cup portion in the soft-pack battery casing is formed at an inclination. This results in an increased space between the outer wall of the cup portion and the electrode assembly. Specifically, if the outer wall of the cup portion formed on the side of the folded portion that integrally connects the first casing to the second casing of the battery casing has an inclination, the outer wall of the cup portion will deform during the subsequent degassing process. This causes the stamping edge on the folded portion side to protrude outwards, resulting in a high-edge phenomenon with increased height. Due to this high-edge shape, the unnecessary thickness of the secondary battery increases, leading to a decrease in energy density relative to volume.

[0010] [Existing Technical Documents]

[0011] (Patent Document 1) Korean Patent Publication No. 2018-0055427 Summary of the Invention

[0012] Technical issues

[0013] One object of the present invention for solving the above-mentioned problems is to provide an apparatus and method for molding a battery casing, and a battery casing in which, when a cup portion is formed by molding a soft film, the outer wall of the cup portion formed on the side of the folded portion that integrally connects the first casing to the second casing is molded to be nearly vertical.

[0014] The purpose of this invention is not limited to the above-described purposes, but other purposes not described herein will be clearly understood by those skilled in the art through the following description.

[0015] Technical solution

[0016] An apparatus for molding a battery casing according to an embodiment of the present invention for achieving the above-mentioned objectives includes: a mold having a top surface, a soft-pack film disposed on the top surface, and the mold including at least one molding space formed to be recessed inward from the top surface; and a punch disposed above the molding space and descending to insert the soft-pack film into the molding space thereby molding the soft-pack film, wherein the top surface of the mold includes at least one mold ramp.

[0017] In addition, the inclined surface of the die can have an inclination that is inclined in the direction of the punch's descent.

[0018] In addition, the molding space can be formed as an inward recess from the mold slope towards the mold interior.

[0019] In addition, the mold slope may include a first mold slope and a second mold slope, and the first mold slope and the second mold slope may be formed symmetrically to each other.

[0020] In addition, the first mold slope and the second mold slope can be inclined downwards as they become adjacent to each other.

[0021] Additionally, the molding space may include: a first molding space, which is formed as an inward recess from the first mold inclined towards the mold; and a second molding space, which is formed as an inward recess from the second mold inclined towards the mold.

[0022] In addition, the mold may include a partition wall formed between the first molding space and the second molding space.

[0023] In addition, the partition wall may have a thickness that gradually increases toward its lower part, and the inner wall of the molded space formed by the partition wall may have an inclination.

[0024] Alternatively, the punch may have a groove at a position corresponding to the partition wall, into which the partition wall is inserted.

[0025] Additionally, the punch may include: a first molding section configured to insert the soft film into a first molding space; and a second molding section configured to insert the soft film into a second molding space.

[0026] Additionally, the mold may include a mold horizontal plane that extends from at least one end of the mold ramp and is perpendicular to the direction of the punch's descent.

[0027] In addition, in the punch, the molding part that is in direct contact with the soft film can have the same inclination as the mold slope.

[0028] Additionally, the device may include a peeler disposed above the mold, descending to contact the mold in the presence of a soft film between them, and configured to secure the soft film.

[0029] Additionally, the bottom surface of the peeler may include at least one peeler ramp that contacts the mold ramp and has the same inclination as the mold ramp.

[0030] A method for molding a battery casing according to an embodiment of the present invention for achieving the above objectives includes: disposing a soft-pack film on the top surface of a mold; lowering a punch disposed above a molding space formed to be recessed inward from the top surface of the mold in a direction inclined relative to at least a portion of the top surface; and inserting the soft-pack film into the molding space by using the punch to form a cup portion in the soft-pack film.

[0031] Additionally, the top surface of the die may include at least one inclined surface when the punch is lowered.

[0032] A battery housing according to an embodiment of the present invention for achieving the above-mentioned objectives includes: a cup portion formed in at least one of a first housing or a second housing, and having an outer wall along an edge of a bottom surface to provide a receiving space for an electrode assembly; and a fold portion folded on one side of the cup portion to integrally connect the first housing to the second housing, wherein the outer wall includes: a first outer wall formed on one side of the fold portion on an edge of a bottom surface; a second outer wall formed on the opposite side of the first outer wall; a third outer wall formed to connect the first outer wall to the second outer wall; and a fourth outer wall formed on the opposite side of the third outer wall, wherein the inward tilt angle between the first outer wall and the bottom is formed in the range of 90° to 95°.

[0033] In addition, the inward inclination angle between the second outer wall and the bottom can be greater than the inward inclination angle between the first outer wall and the bottom.

[0034] In addition, the inward inclination angle between the second outer wall and the bottom can be formed to be more than 10° larger than the inward inclination angle between the first outer wall and the bottom.

[0035] Further details of the embodiments are included in the detailed description and accompanying drawings.

[0036] Beneficial effects

[0037] According to embodiments of the present invention, at least the following effects are achieved.

[0038] The angle between the outer wall of the cup portion formed at the edge of the fold and the bottom can be further reduced to make it nearly vertical. Therefore, the electrode assembly can be set very close to the outer wall of the cup portion to reduce the unnecessary volume of the cup portion.

[0039] In addition, even if the internal pressure of the cup decreases during the degassing process, deformation of the outer wall or bottom of the cup can be prevented to avoid high edge phenomenon.

[0040] In addition, it can reduce the size of bat ears and prevent the problem of bat ears protruding in shape.

[0041] The effects of the present invention are not limited to those described above, and therefore this specification includes many more variations of the effects. Attached Figure Description

[0042] Figure 1 This is an assembly diagram of a secondary battery 1 according to an embodiment of the present invention.

[0043] Figure 2 This is a cross-sectional view of the soft film 135 according to an embodiment of the present invention.

[0044] Figure 3This is a perspective view of device 4 for molding battery casings according to the prior art.

[0045] Figure 4 This is a schematic diagram of a device 4 for molding a battery casing according to the prior art.

[0046] Figure 5 This is a schematic diagram showing the state of the punch 43 descending according to the prior art.

[0047] Figure 6 This is a partially enlarged view showing the stamped edge 3334 of the cup portion 333 according to the prior art.

[0048] Figure 7 This is a partially enlarged view showing the folded portion 339 of a secondary battery 3 according to the prior art.

[0049] Figure 8 This is a schematic top view of a secondary battery 3 based on existing technology.

[0050] Figure 9 This is a flowchart illustrating a method for manufacturing a battery casing 13 by stamping a soft film 135 according to an embodiment of the present invention.

[0051] Figure 10 This is a perspective view of an apparatus 2 for molding a battery casing according to an embodiment of the present invention.

[0052] Figure 11 This is a schematic diagram of an apparatus 2 for molding a battery casing according to an embodiment of the present invention.

[0053] Figure 12 This is a schematic diagram showing the state of the stripper 22 in a descending position according to an embodiment of the present invention.

[0054] Figure 13 This is a schematic diagram showing the state of the punch 23 descending according to an embodiment of the present invention.

[0055] Figure 14 This is a partially enlarged view showing the stamped edge 1334 of the cup portion 133 according to an embodiment of the present invention.

[0056] Figure 15 This is a partially enlarged view showing the folded portion 139 of a secondary battery 1 according to an embodiment of the present invention.

[0057] Figure 16 This is a schematic top view showing a secondary battery 1 according to an embodiment of the present invention.

[0058] Figure 17 This is a perspective view of an apparatus 2a for molding a battery casing according to another embodiment of the present invention.

[0059] Figure 18 This is a schematic diagram of an apparatus 2a for molding a battery casing according to another embodiment of the present invention.

[0060] Figure 19 This is a schematic diagram showing the state of the stripper 22a in a lowered position according to another embodiment of the present invention.

[0061] Figure 20 This is a schematic diagram showing the state of the punch 23a descending according to another embodiment of the present invention.

[0062] Figure 21 This is a partially enlarged view showing the stamped edge 1334a of the cup portion 133a according to another embodiment of the present invention. Detailed Implementation

[0063] The advantages and features of the present invention, as well as its implementation methods, will be illustrated by the embodiments described below in conjunction with the accompanying drawings. However, the invention may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Furthermore, the invention is defined only by the scope of the claims. Throughout the text, the same reference numerals refer to the same parts.

[0064] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as commonly understood by those skilled in the art. Furthermore, unless clearly and explicitly defined in the specification, terms defined in common dictionaries are not ideally or excessively interpreted as having a formal meaning.

[0065] In the following description, technical terms are used only to explain specific exemplary embodiments and are not intended to limit the invention. In this specification, singular terms may include plural forms unless specifically mentioned. The meanings of “comprising” and / or “including” do not exclude other components besides those mentioned.

[0066] The preferred embodiments will be described in detail below with reference to the accompanying drawings.

[0067] Figure 1 This is an assembly diagram of a secondary battery 1 according to an embodiment of the present invention.

[0068] The electrode assembly 10 is formed by alternately stacking electrodes and separators. First, a slurry containing electrode active materials, binders, and plasticizers is applied to the positive and negative current collectors to fabricate electrodes (e.g., positive and negative electrodes). Then, individual separators are stacked between the electrodes to form the electrode assembly 10. The electrode assembly 10 is inserted into the battery housing 13, and electrolyte is injected to seal the battery housing 13.

[0069] Specifically, electrode assembly 10 includes two types of electrodes (e.g., positive and negative electrodes) and a separator inserted between the electrodes to insulate them from each other. Electrode assembly 10 can be stacked, wound, stacked and folded, etc. The two types of electrodes, namely the positive and negative electrodes, each have a structure in which an active material slurry is coated onto an electrode current collector having a metal foil or metal mesh shape. The slurry is typically formed by stirring granular active material, auxiliary conductor, binder, and plasticizer with the addition of a solvent. The solvent can be removed in a subsequent process.

[0070] like Figure 1 As shown, the electrode assembly 10 includes electrode tabs 11. The electrode tabs 11 are respectively connected to the positive and negative electrodes of the electrode assembly 10 and protrude outwards from the electrode assembly 10, thereby providing a path for electrons to move through the electrode assembly 10 between its interior and exterior. The electrode current collector of the electrode assembly 10 consists of a portion coated with an electrode active material and an end without an electrode active material coating, i.e., an uncoated portion. Furthermore, each electrode tab 11 can be formed by cutting the uncoated portion or by ultrasonically welding individual conductive components to the uncoated portion. Figure 1 As shown, the electrode tabs 11 may protrude in various directions of the electrode assembly 10, but are not limited thereto. For example, the electrode tabs may protrude in various directions (e.g., protruding parallel to each other from one side in the same direction).

[0071] In the electrode assembly 10, electrode leads 12 supplying power to the external secondary battery 1 are connected to electrode terminals 11 by spot welding. Furthermore, a portion of the electrode leads 12 is surrounded by an insulating portion 14. The insulating portion 14 can be configured as an edge 134 defined at the thermally fused joint of the first housing 131 and the second housing 132 of the battery housing 13, such that the electrode leads 12 are bonded to the battery housing 13. This prevents electricity generated from the electrode assembly 10 from flowing through the electrode leads 12 to the battery housing 13 and maintains the seal of the battery housing 13. Therefore, the insulating portion 14 can be made of a non-conductive, non-conductive material. While insulating tape, which easily adheres to the electrode leads 12 and has a relatively thin thickness, is typically used as the insulating portion 14, the invention is not limited to this. For example, various components can be used as the insulating portion 14, as long as these components are capable of insulating the electrode leads 12.

[0072] One end of the electrode lead 12 is connected to the electrode tab 11, and the other end of the electrode lead 12 protrudes to the outside of the battery casing 13. That is, the electrode lead 12 includes: a cathode lead 121, one end of which is connected to the cathode plate 111 and extends in the direction in which the cathode plate 111 protrudes; and an anode lead 122, one end of which is connected to the anode plate 112 and extends in the direction in which the anode plate 112 protrudes. On the other hand, as... Figure 1 As shown, the other ends of both the positive lead 121 and the negative lead 122 protrude to the outside of the battery casing 13. Therefore, the electricity generated in the electrode assembly 10 can be supplied to the outside. Furthermore, since the positive terminal 111 and the negative terminal 112 are formed to protrude in different directions, the positive lead 121 and the negative lead 122 can extend in different directions respectively.

[0073] The positive electrode lead 121 and the negative electrode lead 122 can be made of different materials. That is, the cathode lead 121 can be made of the same material as the cathode current collector, namely aluminum (Al), and the anode lead 122 can be made of the same material as the anode current collector, namely copper (Cu) or copper coated with nickel (Ni). In addition, the portion of the electrode lead 12 that protrudes to the outside of the battery casing 13 can also be provided as an end and electrically connected to an external terminal.

[0074] The battery housing 13 is a soft pack made of flexible material, in which the electrode assembly 10 is housed. The case where the battery housing 13 is a soft pack will be described below. When using punch 23 (see...) Figure 10 When a flexible soft film 135 is stretched and formed, a portion of the soft film 135 is stretched to form a cup portion 133 including a soft package containing space 1331, thereby manufacturing a battery casing 13.

[0075] The battery housing 13 accommodates the electrode assembly 10, such that a portion of the electrode leads 12 is exposed and then sealed. For example... Figure 1 As shown, the battery casing 13 includes a first casing 131 and a second casing 132. A receiving space 1331, with a cup portion 133 to accommodate the electrode assembly 10, can be disposed within the first casing 131, and the second casing 132 can cover the upper side of the receiving space 1331, so that the electrode assembly 10 does not separate from the outside of the battery casing 13. Figure 1 As shown, one side of the first housing 131 and one side of the second housing 132 can be connected to each other. However, the invention is not limited thereto. For example, the first housing 131 and the second housing 132 can be manufactured separately to be separable from each other.

[0076] When the cup portion 133 is molded in the flexible film 135, only one cup portion 133 may be formed in one flexible film 135, but the invention is not limited thereto. For example, two cup portions may be stretched and formed adjacent to each other in one flexible film 135. Then, as Figure 1 As shown, cup portions 133 are formed in the first housing 131 and the second housing 132, respectively. Here, the cup portions 133 formed in the first housing 131 and the second housing 132 may have the same depth D, but are not limited to this, and may have different depths D. After the electrode assembly 10 is accommodated in the receiving space 1331 provided in the cup portion 133 of the first housing 131, the battery housing 13 can be folded relative to the bridge portion 136 formed between the two cup portions 133 in the battery housing 13, such that the two cup portions 133 face each other. Then, the cup portion 133 of the second housing 132 also accommodates the electrode assembly 10 from its upper side. Therefore, since two cup portions 133 accommodate one electrode assembly 10, an electrode assembly 10 with a thicker thickness can be accommodated compared to the case where only one cup portion 133 is provided. Furthermore, since the first housing 131 and the second housing 132 are integrally connected to each other by folding the battery housing 13, the number of edges 134 to be sealed during the subsequent sealing process can be reduced. Therefore, the process speed can be increased and the number of sealing processes can be reduced.

[0077] The battery housing 13 may include: a cup portion 133, in which a receiving space 1331 for accommodating the electrode assembly 10 is provided; and a degassing portion 137, formed on the side of the cup portion 133 to discharge gas generated in the cup portion 133 through a degassing hole H. When the electrode assembly 10 is accommodated in the cup portion 133 of the battery housing 13 and an electrolyte is injected, and then an activation process is performed, gas is generated inside the battery housing 13. After a degassing process is performed by punching a degassing hole in the degassing portion 137 to discharge the gas to the outside, the degassing portion 137 can be sealed and cut off for removal.

[0078] When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10, and an insulating portion 14 is formed on a part of the electrode lead 12, the electrode assembly 10 is housed in a receiving space 1331 provided in the cup portion 133 of the first housing 131, and the second housing 132 covers the receiving space from above. Furthermore, an electrolyte is injected into the receiving space, and the edges 134 extending to the outer sides of the cup portions 133 of the first housing 131 and the second housing 132 are sealed. The electrolyte allows lithium ions generated by the electrochemical reaction of the electrodes during the charging and discharging of the secondary battery 1 to move. The electrolyte may include a non-aqueous organic electrolyte, which is a mixture of lithium salt and high-purity organic solvent, or a polymer electrolyte. Furthermore, the electrolyte may include a sulfide, oxide, or polymer solid electrolyte, and the solid electrolyte may have flexibility that allows it to be easily deformed by external force. The pouch-type secondary battery 1 can be manufactured by the above method.

[0079] Figure 2 This is a cross-sectional view of the soft film 135 according to an embodiment of the present invention.

[0080] According to one embodiment of the present invention, the battery casing 13 of the pouch-type secondary battery 1 can be manufactured by stretching the pouch film 135. That is, the battery casing 13 is manufactured by stretching the pouch film 135 using a punch 23 or the like to form a cup portion 133. Figure 2 As shown, the flexible film 135 includes a sealant layer 1351, a moisture barrier layer 1352, and a surface protective layer 1353.

[0081] The sealant layer 1351 can be made of a first polymer and formed in the innermost layer to directly contact the electrode assembly 10. Here, the innermost layer refers to the last layer when it is oriented in a direction opposite to that of the electrode assembly 10 relative to the direction in which the moisture barrier layer 1352 is disposed. When a soft-pack film 135 having the stacked structure described above is stretched and formed using a punch 23 or the like, the battery housing 13 can be manufactured while stretching a portion of the soft-pack film 135 to form a cup portion 133 including a receiving space 1331 having a soft-pack shape. Furthermore, when the electrode assembly 10 is accommodated in the receiving space 1331, an electrolyte is injected. Subsequently, when the first housing 131 and the second housing 132 come into contact with each other so that they face each other, and thermal compression is applied to the edges 134, the sealant layers 1351 adhere to each other to seal the battery housing 13. Here, since the sealant layer 1351 is in direct contact with the electrode assembly 10, the sealant layer 23 must have insulating properties. Furthermore, since the sealant layer 23 is in contact with the electrolyte, the sealant layer 23 must have corrosion resistance. Furthermore, since the interior of the battery casing 13 is completely sealed to prevent material movement between the interior and exterior of the battery casing 13, high sealing performance must be achieved. That is, the edges 134 where the sealant layers 1351 are bonded together should have excellent thermal bonding strength. Typically, the first polymer forming the sealant layer 1351 can include one or more materials selected from: polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Specifically, polyolefin resins such as polypropylene (PP) or polyethylene (PE) are used for the sealant layer 23. Polypropylene (PP) has excellent mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, as well as excellent chemical properties such as corrosion resistance, and is therefore primarily used in the manufacture of the sealant layer 1351. Furthermore, the sealant layer 23 can be made of cast polypropylene, acid-modified polypropylene, or a polypropylene-butene-ethylene terpolymer. Here, the acid-treated polypropylene can be maleic anhydride polypropylene (MAH PP). Furthermore, the sealant layer 1351 can have a single-layer structure made of one material, or a composite layer structure in which two or more materials are formed as layers.

[0082] A moisture barrier layer 1352 is stacked between the surface protective layer 1353 and the sealant layer 1351 to ensure the mechanical strength of the soft pack, prevent the introduction and release of gas or moisture from the outside of the secondary battery 1, and prevent electrolyte leakage. The moisture barrier layer 1352 can be made of a metal, specifically a metal comprising an aluminum alloy. Aluminum ensures mechanical strength above a predetermined level while being lightweight. Therefore, aluminum can improve electrochemical performance and ensure heat dissipation for the electrode assembly 10 and the electrolyte. The aluminum alloy can include a variety of materials, such as one or more selected from iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg), and zinc (Zn). Here, the moisture barrier layer 1352 is made of a material containing iron, which can improve mechanical strength. When the moisture barrier layer 1352 is made of a material containing aluminum, flexibility can be improved. Therefore, the material forming the moisture barrier layer 1352 can be used with consideration of the characteristics of the moisture barrier layer 1352.

[0083] The surface protective layer 1353 is made of a second polymer and formed on the outermost layer to protect the secondary battery 1 from external friction and impact, and also to electrically insulate the electrode assembly 10 from the outside. Here, the outermost layer refers to the last layer disposed when oriented in a direction opposite to the direction in which the electrode assembly 10 is disposed relative to the moisture barrier layer 1352. The second polymer forming the surface protective layer 1353 may include one or more materials selected from polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Specifically, polymers with abrasion resistance and heat resistance, such as polyethylene terephthalate (PET), may be used primarily. Furthermore, the surface protective layer 1353 may have a single-layer structure made of one material, or a composite layer structure in which two or more materials are respectively formed as layers.

[0084] Although PET is inexpensive, has excellent durability, and excellent electrical insulation, it has poor adhesion to aluminum, which is often used in the moisture barrier layer 1352, and its behavior differs when stretched under pressure. Therefore, when the surface protective layer 1353 and the moisture barrier layer 1352 are directly bonded together, they peel off during stretching. Consequently, the moisture barrier layer 1352 is stretched unevenly, leading to deterioration in molding performance.

[0085] According to one embodiment of the invention, the battery casing 13 may be made of a third polymer and further includes a stretching aid layer (not shown) stacked between the surface protective layer 1353 and the moisture barrier layer 1352. The stretching aid layer is stacked between the surface protective layer 1352 and the moisture barrier layer 1352 to prevent the surface protective layer 1353 and the moisture barrier layer 1352 from peeling off when the surface protective layer 1352 and the moisture barrier layer 1352 are stretched. The third polymer forming the stretching aid layer 1354 may include one or more materials selected from polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aromatic polyamide, nylon, polyester, poly(p-phenylenebenzodioxazole), polyarylate, polytetrafluoroethylene, and glass fiber. Specifically, since nylon resin readily adheres to the polyethylene terephthalate (PET) of the surface protective layer 1352 and behaves similarly to the aluminum alloy of the moisture barrier layer 1352 during stretching, it is preferable to primarily use nylon resin. Furthermore, the stretching aid layer can have a single-layer structure made of one material, or a composite layer structure in which two or more materials are each formed as a layer.

[0086] Figure 3 This is a perspective view based on an existing device 4 for molding battery casings. Figure 4 This is a schematic diagram of a device 4 for molding a battery casing according to the prior art.

[0087] like Figure 3 and Figure 4 As shown, the apparatus 4 for molding a battery casing according to the prior art includes: a mold 41 having a soft film 135 disposed on its top surface 412 and including a molding space 411 formed to be recessed inward from the top surface 412; a peeler 42 disposed above the mold 41 and contacting the mold 41 with the soft film 135 therebetween when it descends to fix the soft film 135; and a punch 43 disposed above the molding space 411 and located at the center portion of the peeler 42, and descending to insert the soft film 135 into the molding space 411 to mold the soft film 135.

[0088] First, such as Figure 4 As shown, a flexible film 135 is disposed on the top surface 412 of the mold 41. Here, the flexible film 135 is disposed on the top surface 412 of the mold 41 such that the forming space 411 is located in the region where the cup portion 333 will be formed laterally. According to the prior art, the top surface 412 of the mold 41 is formed horizontally relative to the ground. Therefore, the flexible film 135 is also mounted parallel to the ground on the top surface 412 of the mold 41.

[0089] Figure 5 This is a schematic diagram showing the state of the punch 43 descending according to the prior art.

[0090] like Figure 5 As shown, the peeler 42 is positioned above the mold 41 so that it descends when the soft film 135 is applied to the top surface 412 of the mold 21. Furthermore, the peeler 42 contacts the mold 21 with the soft film 135 in between and presses the soft film 135 upward to secure it.

[0091] The punch 43 descends at a predetermined pressure and speed to apply pressure to the top surface of the soft-pack film 135 disposed on the mold 41, thereby stretching the soft-pack film 135. As a result, a cup portion 333 can be formed in the soft-pack film 135 to manufacture a soft-pack battery casing 33.

[0092] The punch 43 has a shape and size corresponding to the forming space 411 of the mold 41. Here, the shape of the punch 43 and the forming space 411 corresponding to each other means that the punch 43 and the forming space 411 of the mold 41 have the same or similar shapes, and when the soft film 135 is stretched to form the cup portion 333, the cup portion 333 has the same or similar shapes as the punch 23 and the forming space 411 of the mold 41, respectively. In addition, the corresponding size means that when the punch 43 is inserted into the forming space 411 of the mold 41 with the soft film 135 and the soft film 135 is stretched, the final punch 43 has a gap CL smaller than the forming space 411 of the mold 41.

[0093] The clearance CL refers to the horizontal distance between the inner wall 414 of the forming space 411 of the mold 41 and the outer wall 3333 of the punch 43. In reality, there is a slight difference in size between the forming space 411 of the mold 41 and the punch 43, approximately equal to the clearance CL. If the clearance CL is too small, the distance between the inner wall of the forming space 411 and the outer wall of the punch 43 will be too small. Consequently, the soft membrane 135 may not be able to be inserted into the forming space 411, or the soft membrane 135 may be damaged due to excessive friction.

[0094] According to the prior art, the bottom surface 422 of the peeler 42 and the molding portion 431 of the punch 43 are also formed horizontally relative to the ground. Therefore, when the cup portion 333 is formed by molding the soft film 135, the bottom 3332 of the cup portion 333 is also formed horizontally relative to the ground.

[0095] Figure 6 This is a partially enlarged view showing the stamped edge 3334 of the cup portion 333 according to the prior art.

[0096] In the battery housing 33, the edge of the cup portion 333 includes various types of edges, such as stamping edges 3334, die edges, and thickness edges. Among them, the stamping edge 3334 is formed as an edge corresponding to the punch 43 and connects the multiple outer walls 3333 surrounding the periphery of the cup portion 333 to the bottom 3332 respectively.

[0097] The gap CL is the horizontal distance between the inner wall 414 of the forming space 411 of the mold 41 and the outer wall 432 of the punch 43. It can be described as the horizontal distance between the upper end of the outer wall 3333 of the cup portion 333 and the edge boundary between the stamping edge 3334 and the outer wall 3333 of the cup portion 333 in the battery housing 33. However, as mentioned above, when the gap CL increases, the inclination angle C between the outer wall 3333 of the cup portion 333 and the bottom 3332 in the soft-pack battery housing 33 increases. Therefore, there is a problem of increased space between the outer wall 3333 of the cup portion 333 and the electrode assembly 10. In fact, even if the gap CL is minimized, according to the prior art, the inclination angle C between the outer wall 3333 of the cup portion 333 and the bottom 3332 is less than 95°, and there are limitations in molding to be close to vertical.

[0098] Figure 7 This is a partially enlarged view showing the folded portion 339 of the secondary battery 3 according to the prior art. Figure 8 This is a schematic top view of a secondary battery 3 based on existing technology.

[0099] During the degassing process in the secondary battery 3, the internal pressure of the cup portion 333 decreases as gas is discharged from the inside of the battery casing 33 to the outside. Therefore, according to the prior art, in order to reduce the volume of the space between the outer wall 3333 of the cup portion 333 and the electrode assembly 10 while reducing the internal pressure of the cup portion 333, the outer wall 3333 or the bottom 3332 of the cup portion 333 will deform. Specifically, as Figure 7 As shown, because the outer wall 3333 of the folded portion 339 of the secondary battery 3 is recessed inward, a high-edge phenomenon occurs where the stamped edge 3334 of the folded portion 339 of the cup portion 333 protrudes outward to increase its height. Due to this high-edge phenomenon, the unnecessary thickness of the secondary battery 3 increases, resulting in a decrease in energy density relative to volume. Furthermore, because the outer wall 3333 of the folded portion 339 of the cup portion 333 deforms, the appearance of the secondary battery 3 is unattractive, thus reducing its marketability.

[0100] In addition, such as Figure 8As shown, the size of the bat ears 35 is further increased, and the high edge phenomenon causes a problem of protruding shape. The bat ears 35 are the parts that appear visually when they protrude outward from both ends of the fold portion 339. When the size of the bat ears 35 is large, the unnecessary volume of the secondary battery 3 is further increased, thus causing errors between the design values ​​and actual values ​​of the shape and size of the secondary battery 3. Therefore, the problem is that it is not easy to assemble the secondary battery 3 into the battery module 5 (not shown), and considering the bat ears 35, the size of the secondary battery 3 must be designed to be small from the beginning. In addition, due to the increased volume of the secondary battery 3, there is also a problem of reduced energy density relative to volume. Furthermore, the problem is that when the secondary battery 3 is housed in the outer shell (not shown) of the battery module, the bat ears 35 greatly separate the outer shell from the fold portion 339, thereby degrading the cooling efficiency of the secondary battery 3.

[0101] Figure 9 This is a flowchart illustrating a method for manufacturing a battery casing 13 by stamping a soft film 135 according to an embodiment of the present invention.

[0102] According to one embodiment of the invention, the inclination angle between the outer wall 1333 and the bottom 1332 of the cup portion 133 is further reduced to be nearly vertical. Therefore, since the electrode assembly 10 is positioned very close to the outer wall 1333 of the cup portion 133, unnecessary volume of the cup portion 133 can be reduced. Furthermore, even when the internal pressure of the cup portion 133 decreases during the degassing process, deformation of the outer wall 1333 or the bottom 1332 of the cup portion 133 can be prevented, thus preventing high-edge phenomena. Additionally, the size of the "bat ears" 15 can be reduced, and the problem of the bat ears 15 protruding in shape can be prevented.

[0103] Therefore, a method for molding a battery casing according to an embodiment of the present invention includes: a step of disposing a soft film 135 on the top surface of a mold 21 (S901); a step of lowering a punch 23 disposed above a molding space 211 recessed inward from the top surface of the mold 21 in a direction having an inclination at least a portion of the top surface (S903); and a step of inserting the soft film 135 into the molding space 211 by using the punch 23 to form a cup portion 133 in the soft film 135 (S904).

[0104] In the following text, reference will be made to Figures 10 to 21 describe Figure 9 The flowchart shown illustrates the contents of each step.

[0105] Figure 10 This is a perspective view showing an apparatus 2 for molding a battery casing according to an embodiment of the present invention. Figure 11This is a schematic diagram of an apparatus 2 for molding a battery casing according to an embodiment of the present invention.

[0106] like Figure 10 and Figure 11 As shown, an apparatus 2 for molding a battery casing according to an embodiment of the present invention includes: a mold 21 having a flexible film 135 disposed on its top surface and including a molding space 211 formed to be recessed inward from the top surface; and a punch 23 disposed above the molding space 211 and descending to insert the flexible film 135 into the molding space 211 to mold the flexible film 135. The top surface of the mold 21 includes at least one mold ramp 212. Furthermore, the apparatus 2 for molding a battery casing may also include a peeler 22 disposed above the mold 21, which descends to contact the mold 21 when the flexible film 135 is present, and secures the flexible film 135.

[0107] A flexible film 135 is disposed on the top surface of the mold 21. Here, the film 135 is disposed such that the forming space 211 is located in the area where the cup portion 133 is to be formed. The top surface of the mold 21 includes at least one mold ramp 212, which is inclined relative to the direction of descent of the punch 23. Furthermore, the top surface of the mold 21 may also include a mold horizontal surface 213, which extends from at least one end of the mold ramp 212 and is perpendicular to the direction of descent of the punch 23. The mold horizontal surface 213 may be perpendicular to the direction of descent of the punch 23, but it may also be formed horizontally relative to the ground. Therefore, after molding the film 135, a portion of the film 135 disposed on the mold horizontal surface 213 can be formed horizontally relative to the ground without inclination. For example, to facilitate subsequent fixation of the film 135, a grid pattern or minute irregularities may be formed on the top surface of the mold 21.

[0108] According to one embodiment of the present invention, two cup portions 133 can be stretched and formed adjacent to each other on a soft film 135. That is, the cup portions 133 can be formed in the first housing 131 and the second housing 132, respectively. Therefore, as Figure 10 and Figure 11 As shown, the mold inclined surface 212 includes a first mold inclined surface 2121 and a second mold inclined surface 2122, which can be formed symmetrically with respect to each other. Here, symmetrical formation means that the line formed at the point where the first mold inclined surface 2121 and the second mold inclined surface 2122 contact each other becomes the central axis, and the first mold inclined surface 2121 and the second mold inclined surface 2122 are formed symmetrically with respect to the central axis. Furthermore, since they are adjacent to each other, the first mold inclined surface 2121 and the second mold inclined surface 2122 can have a downward inclination, thereby, the mold 21 can be formed into a downwardly concave shape.

[0109] The mold 21 includes at least one forming space 211 recessed inward from the top surface of the mold 21. The forming space 211 has a shape and size corresponding to the outer surface of the cup portion 133 formed later. Here, the corresponding shape means that when the cup portion 133 is formed later by stretching the soft film 135 using the punch 23, the cup portion 133 has the same or similar shape as the punch 23 and the forming space 411 of the mold 21. Therefore, if the cross-section of the cup portion 133 has a rectangular shape, the cross-section of the forming space 211 can also have a rectangular shape. If the cross-section of the cup portion 133 has a circular shape, the cross-section of the forming space 211 can also have a circular shape. Furthermore, the corresponding size means that when the punch 23 stretches the soft film 135, the punch 23 and the soft film 135 are inserted together into the forming space 211 of the mold 21, so the cup portion 133 has a size slightly smaller than the forming space 211 of the mold 21. In addition, the forming space 211 is formed in a direction parallel to the direction of descent of the punch 23. Therefore, if the punch 23 inserted into the forming space 211 continues to descend in the descending direction, the punch moves along the forming space 211, and the soft film 135 is molded in the direction in which the punch 23 moves.

[0110] According to one embodiment of the present invention, the molding space 211 is formed to be recessed from the mold ramp 212 into the interior of the mold 21, and includes: a first molding space 2111, formed to be recessed from the first mold ramp 2121 into the interior of the mold 21; and a second molding space 2112, formed to be recessed from the second mold ramp 2122 into the interior of the mold 21. Furthermore, the mold 21 also includes a partition wall 215 formed between the first molding space 2111 and the second molding space 2112. When molding the soft-pack film 135, bridge portions 136 corresponding to the partition wall 215 are formed in the battery casing 13.

[0111] When the battery casing 13 is later folded, the bridge portion 136 can serve as a reference portion. When the secondary battery 1 is manufactured, the bridge portion 136 can form a fold portion 139 on one side of the secondary battery 1 (see...). Figure 16 Since the folding portion 139 integrally connects the first housing 131 to the second housing 132, the number of edges 134 to be sealed can be reduced during subsequent sealing processes. Therefore, the process speed can be increased, and the number of sealing processes can be reduced. Here, as the width of the folding portion 139 decreases, the space between the outer wall 1333 of the cup portion 133 and the electrode assembly 10 also decreases. Therefore, due to the reduction in the overall volume of the secondary battery 1, the energy density relative to volume increases.

[0112] Since the width of the fold 139 is proportional to the thickness of the bridge 136, and the bridge 136 is formed to correspond to the partition wall 215, the thickness of the bridge 136 is proportional to the thickness of the partition wall 215. Therefore, when molding the soft film 135, the thickness of the bridge 136 can be minimized, and thus the thickness of the partition wall 212 can be minimized. However, if the partition wall 212 is formed to have an excessively high height in a thin state, the partition wall 215 will be damaged during the stretch forming process. Specifically, according to the prior art, the mold 21 has a bottom, but in this case, the problem is that when the punch 23 molds the soft film 135, the gas between the soft film 135 and the forming space 211 is not discharged. Therefore, recently, the bottom of the mold 21 can be removed so that the gas between the soft film 135 and the forming space 211 can be easily discharged, but the problem is that the height of the partition wall 215 will be too high. Therefore, according to an embodiment of the present invention, as Figure 11 As shown, the partition wall 215 may have a thickness that gradually increases towards its lower portion. That is, at least a portion of the cross-section of the partition wall 215 may have a generally triangular shape, and the inner wall 214 of the forming space 211 formed in the partition wall 215 may have an inclination. The precise inclination of the inner wall 214 of the forming space 211 formed in the partition wall 215 can be experimentally determined by the thickness of the upper portion of the partition wall 215, the material of the partition wall 215, the pressure of the punch 23, and the depth of the cup portion 133 to be formed.

[0113] However, the invention is not limited thereto, and the upper portion of the partition wall 215 can be kept to a minimum thickness, while a reinforcing portion (not shown) with a greater thickness than the partition wall 215 can be formed at the lower portion of the partition wall 215. The reinforcing portion can be formed to a depth greater than the cup portion 133 formed in the battery casing 13, and can be formed at a location that does not damage the partition wall 215. The exact location of the reinforcing portion can be experimentally determined based on the thickness of the upper portion of the partition wall 215, the material of the partition wall 215, the pressure of the punch 23, and the depth of the cup portion 133 to be formed. Therefore, the strength of the partition wall 215 can be increased to prevent damage to the partition wall 215 during the stretch forming process.

[0114] The peeler 22 is positioned above the mold 21, allowing it to descend when the flexible film 135 is placed on the top surface of the mold 21. Furthermore, the peeler 22 contacts the mold 21 with the flexible film 135 in between, and presses the flexible film 135 upwards to secure it. Here, "the peeler 22 contacts the mold 21 with the flexible film 135 in between" means that the parts do not directly contact each other, but rather indirectly contact each other through the flexible film 135. When the punch 23 is subsequently used to mold the flexible film 135, the peeler 22 uniformly presses the flexible film 135 to evenly distribute the tensile force applied to the flexible film 135.

[0115] Therefore, when the flexible film 135 is fixed, the bottom surface of the peeler 22 contacts the top surface of the flexible film 135. Thus, the bottom surface of the peeler 22 can have a shape corresponding to the top surface of the mold 21. That is, since the top surface of the mold 21 includes at least one mold ramp 212 and a mold horizontal surface 213 extending from at least one end of the mold ramp 212, the bottom surface of the peeler 22 includes: at least one peeler ramp 222 that contacts the mold ramp 212 and has the same inclination as the mold ramp 211; and a peeler horizontal surface 223 that contacts the mold horizontal surface 213 and extends from at least one end of the peeler ramp 222.

[0116] Therefore, when the soft film 135 is secured, the bottom surface of the peeler 22 contacts the top surface of the soft film 135. Furthermore, to facilitate subsequent securing of the soft film 135, a grid pattern or minute irregularities can be formed on the bottom surface of the peeler 22.

[0117] According to one embodiment of the invention, the mold bevel 212 includes a first mold bevel 2121 and a second mold bevel 2122 formed symmetrically to each other. Therefore, the peeler bevel 222 also includes a first peeler bevel 2221 and a second peeler bevel 2222. The first peeler bevel 2221 contacts the first mold bevel 2121 when a soft membrane 135 is present therebetween, and the second peeler bevel 2222 contacts the second mold bevel 2122 when a soft membrane 135 is present therebetween. Therefore, the first peeler bevel 2221 may have the same inclination as the first mold bevel 2121, and the second peeler bevel 2222 may have the same inclination as the second mold bevel 2122. The first peeler bevel 2221 and the second peeler bevel 2222 may also be formed symmetrically to each other and may have an inclination that slopes downward toward the center.

[0118] A punch 23 is positioned above the forming space 211 of the mold 21 and descends to insert a soft-pack film 135 into the forming space 211 to mold the soft-pack film 135. The punch 23 descends at a predetermined pressure and speed. Then, while being inserted into the forming space 211 of the punch 23, the molding portion 231 of the punch 23 directly contacts the top surface of the soft-pack film 135 provided on the mold 21 to apply pressure to the soft-pack film 135, thereby stretching the soft-pack film 135. Therefore, a cup portion 133 can be formed in the soft-pack film 135 to manufacture a soft pack. A through portion 221 is formed approximately at the center of the peeler 22. Furthermore, the punch 23 passes through the peeler 22 via the through portion 221 to move vertically. When the punch 23 moves vertically, the through portion 221 has a shape and size corresponding to the punch 23, such that the inner wall of the through portion 221 guides the punch 23. Here, the correspondence between the shapes of the through portion 221 and the punch 23 means that the through portion 221 and the punch 23 have the same or similar shapes, making it easy for the punch 23 to move upward and downward through the through portion 221. Furthermore, the corresponding size means that the final size of the through portion 221 is larger than the size of the punch 23. If the size of the through portion 221 is equal to or smaller than the size of the punch 23, the punch 23 cannot move vertically through the through portion 221 due to friction with the inner wall of the through portion 221, or the punch 23 cannot move vertically easily. On the other hand, if the size of the through portion 221 is too large, the inner wall of the through portion 221 cannot guide the punch 23, and thus, the punch 23 will separate from its fixed position. Therefore, preferably, the through portion 221 has a size that allows the punch 23 to be inserted into the through portion 221 and move vertically easily without separating from its fixed position. In practice, the through portion 221 can be experimentally determined based on the size and shape of the cup portion 133 to be formed.

[0119] Furthermore, the punch 23 has a shape and size corresponding to the forming space 211 of the mold 21. Here, the shape of the punch 23 and the forming space 211 corresponding to each other means that the punch 23 and the forming space 211 of the mold 21 have the same or similar shapes, and when the soft film 135 is stretched to form the cup portion 133, the cup portion 133 has the same or similar shapes as the punch 23 and the forming space 211 of the mold 21, respectively. Therefore, if the punch 23 has a rectangular shape, the forming space 211 of the mold 21 can also have a rectangular shape, and the cup portion 133 can also have a rectangular shape. If the punch 23 has a circular shape, the forming space 211 of the mold 21 can also have a circular shape, and the cup portion 133 can also have a circular shape. In addition, the corresponding size means that the punch 23 has a size that is slightly smaller than the thickness of the soft film 135 than the forming space 211 of the mold, because the punch 23 is inserted into the forming space 211 of the mold 21 with the soft film 135 to stretch the soft film 135.

[0120] According to one embodiment of the present invention, as described above, the molding space 211 of the mold 21 includes a first molding space 2111 and a second molding space 2112, and the mold 21 also includes a partition wall 215 formed between the first molding space 2111 and the second molding space 2112. Therefore, since the punch 23 has a shape corresponding to the mold 21, the molding portion 231 of the punch 23 includes: a first molding portion 2311 for inserting the soft film 135 into the first molding space 2111, and a second molding portion 2312 for inserting the soft film 135 into the second molding space 2112. A groove for inserting the partition wall 215 is formed between the first molding portion 2311 and the second molding portion 2312 at a position corresponding to the partition wall 215 of the mold 21.

[0121] Figure 12 This is a schematic diagram showing the state of the peeler descending according to an embodiment of the present invention.

[0122] When the soft film 135 is placed on the top surface of the mold 21 (S901), the peeler 22 descends (S902), as... Figure 12 As shown in the diagram, when the top surface of the soft film 135 contacts the bottom surface of the peeler 22, the peeler 22 and the mold 21 are in contact with each other with the soft film 135 between them. Furthermore, the peeler 22 presses the soft film 135 upwards to secure it. Thus, when the cup portion 133 is formed later, the peeler 22 uniformly presses the soft film 135 to evenly distribute the tensile force applied to the soft film 135.

[0123] Here, the peeler inclined surface 222 and the mold inclined surface 212 are in contact with each other with a soft film 135 between them, and the peeler horizontal surface 223 and the mold horizontal surface 213 are in contact with each other with a soft film 135 between them. Therefore, as Figure 12 As shown, the soft film 135 in the area where the peeler inclined surface 222 and the mold inclined surface 212 are in contact with each other is formed with an inclination, and the soft film 135 in the area where the peeler horizontal surface 223 and the mold horizontal surface 213 are in contact with each other is formed horizontally without inclination.

[0124] Specifically, according to one embodiment of the invention, the mold inclined surface 212 includes a first mold inclined surface 2121 and a second mold inclined surface 2122 formed symmetrically to each other. Furthermore, the first mold inclined surface 2121 and the second mold inclined surface 2122 may have a downward inclination as they approach each other. Therefore, as... Figure 12 As shown, the soft film 135 in the area where the peeler slope 222 and the mold slope 212 contact each other is symmetrical on both sides and may have an inclination that slopes downward toward the center.

[0125] Figure 13This is a schematic diagram showing the state of the punch 23 descending according to an embodiment of the present invention.

[0126] When the peeler 22 fixes the soft film 135, as Figure 13 As shown, the punch 23 descends in a direction inclined relative to the top surface of the mold 21, specifically, the mold ramp 212 (S903). Then, the punch 23 is inserted into the forming space 211 having the soft-pack film 135, and the soft-pack film 135 is stretched (S903). Thus, the soft-pack film 135 can be molded to form a cup portion 133 (S904). Subsequently, when the punch 23 and the peeler 22 rise again, the soft-pack film 135 in which the cup portion 133 is formed can be removed, thereby manufacturing a soft-pack battery casing 13 according to an embodiment of the present invention.

[0127] As described above, the molding portion 231 of the punch 23 directly contacts the top surface of the soft-pack film 135 provided on the mold 21 to apply pressure, thereby stretching the soft-pack film 135. Furthermore, when molding the soft-pack film 135 to form the cup portion 133, the bottom 1332 of the cup portion 133 is formed in a shape corresponding to the molding portion 231 of the punch 23. Here, the molding portion 231 of the punch 23 may also be formed with an inclination angle; specifically, it may have the same inclination angle as the mold inclined surface 212. Therefore, when molding the soft-pack film 135 to manufacture the battery casing 13, the bottom 1332 of the cup portion 133 of the battery casing 13 may have the same inclination angle as the soft-pack film 135 in the area where the peeler inclined surface 222 and the mold inclined surface 212 contact each other, thereby making the bottom 1332 parallel to the soft-pack film 135. However, the invention is not limited thereto, and the molding portion 231 of the punch 23 may have a different tilt angle than the mold slope 212. In this case, the bottom 1332 of the cup portion 133 of the battery housing 13 may be formed with a tilt angle different from that of the soft film 135 in the area where the peeler slope 222 and the mold slope 212 contact each other.

[0128] According to one embodiment of the present invention, since the mold slope 212 includes a first mold slope 2121 and a second mold slope 2122, the molding portion 231 of the punch 23 may also include a first molding portion 2311 and a second molding portion 2312. The first molding portion 2311 of the punch 23 is inserted into the first forming space 2111 of the mold 21 to stretch the soft film 135. Then, a cup portion 133 can be formed in the first housing 131. Here, the bottom 1332 of the cup portion 133 formed in the first housing 131 may have an inclination angle that is the same as the inclination angle of the soft film 135 in the area where the first mold slope 2121 and the first peeler slope 2221 contact each other, thereby the bottom 1332 may be parallel to the soft film 135. Furthermore, the second molding portion 2312 of the punch 23 is inserted into the second forming space 2112 of the mold 21 to stretch the soft film 135. Therefore, the cup portion 133 can be formed in the second housing 132. Here, the bottom 1332 of the cup portion 133 formed in the second housing 132 may have the same angle of inclination as the soft film 135 in the area where the second mold slope 2122 and the second peeler slope 2222 contact each other, so that the bottom 1332 may be parallel to the soft film 135.

[0129] Therefore, when molding the soft film 135 to manufacture the battery casing 13, the bottom 1332 of the cup portion 133 formed in the first casing 131 and the second casing 132 can also be formed symmetrically to each other and can have an inclination that slopes downward toward the center.

[0130] When the punch 23 descends and inserts into the forming space 211 of the mold 21, the partition wall 215 of the mold 21 can be inserted into the groove formed between the first molding portion 2311 and the second molding portion 2312 of the punch 23. Therefore, when molding the soft-pack film 135, a bridge portion 136 corresponding to the partition wall 215 of the mold 21 can be formed on the battery casing 13. The bridge portion 136 is formed to correspond to the partition wall 215 of the mold 21, and the stamping edge 1334 is formed to correspond to the edge of the punch 23. Furthermore, the gap CL is the horizontal distance between the inner wall 214 of the forming space 211 of the mold 21 and the outer wall 232 of the punch 23, existing between the inner wall 214 of the forming space 211 of the mold 21 and the outer wall 232 of the punch 23. Therefore, as... Figure 13 As shown, the gap CL can be referred to as the horizontal distance between the bridge portion 136 and the stamping edge 1334 in the battery housing 13, and the outer wall 1333 of the cup portion 133 can be formed with an inclination having the gap CL.

[0131] Figure 14 This is a partially enlarged view showing the stamped edge 1334 of the cup portion 133 according to an embodiment of the present invention.

[0132] like Figure 14 As shown, although the outer wall 1333 of the cup portion 133 itself is formed with an inclination, according to an embodiment of the invention, the bottom 1332 of the cup portion 133 is also formed with an inclination. Therefore, the inclination angle α between the bottom 1332 of the cup portion 133 and the outer wall 1333 can be further reduced to be nearly vertical, so as to have an inclination angle between about 90° and about 95°, and further, between 90° and 93°.

[0133] Figure 15 This is a partially enlarged view showing the folded portion 139 of a secondary battery 1 according to an embodiment of the present invention.

[0134] According to one embodiment of the present invention, the inclination angle α between the outer wall 1333 of the cup portion 133 and the bottom 1332 can be formed to be nearly perpendicular. Therefore, since the electrode assembly 10 is disposed very close to the outer wall 1333 of the cup portion 133, unnecessary volume of the cup portion 133 is reduced. Therefore, even if the internal pressure of the cup portion 133 decreases through a degassing process, deformation of the outer wall 1333 or the bottom 1332 of the cup portion 133 can be prevented. That is, as... Figure 15 As shown, this prevents high-edge phenomena from occurring, thus ensuring that the energy density relative to volume does not decrease.

[0135] Figure 16 This is a schematic top view showing a secondary battery 1 according to an embodiment of the present invention.

[0136] As described above, the "bat ears" 15 are the portions that visually appear when a portion of each end of the folded portion 139 protrudes outward from the secondary battery 1. Specifically, the battery casing 13 is formed by stretching the soft film 135, in which case not only is the cup portion 133 stretched to a limited extent, but the peripheral edge 134 of the cup portion 133 is also stretched slightly as a whole. Therefore, when the bridge portion 136 is folded, the slightly stretched portion of the edge 134 accumulates as it protrudes outward from both ends of the folded portion 139 and thus appears visually. This is referred to as the "bat ears" 15.

[0137] According to one embodiment of the present invention, since the occurrence of high edge phenomenon is prevented, the size of the bat ears 15 can be reduced, and the problem of the bat ears 15 protruding in shape can be prevented. Therefore, the secondary battery 1 can be easily assembled into the battery module, and the unnecessary reduction in the volume of the secondary battery 1 results in an increase in energy density relative to volume. Furthermore, when the secondary battery 1 is housed in the outer casing of the battery module, the size of the bat ears 15 can be reduced, the gap between the outer casing and the folding portion 139 can be reduced, and the cooling efficiency of the secondary battery 1 can also be improved.

[0138] Figure 17 This is a perspective view of an apparatus 2a for molding a battery casing according to another embodiment of the present invention. Figure 18 This is a schematic diagram of an apparatus 2a for molding a battery casing according to another embodiment of the present invention.

[0139] According to one embodiment of the invention, two cup portions 133 are formed adjacent to each other in a soft film 135, so that the cup portions 133 can be formed in the first housing 131 and the second housing 132, respectively. However, according to another embodiment of the invention, only one cup portion 133 can be formed in a soft film 135, so that the cup portion 133 can be formed only in the first housing 131. Therefore, as Figure 17 As shown, the top surface of the mold 21a may include only one mold ramp 212a, which is inclined relative to the direction of descent of the punch 23a. In addition, the top surface of the mold 21a may also include multiple mold horizontal surfaces 213a, which extend from both ends of the mold ramp 212a and are perpendicular to the direction of descent of the punch 23a.

[0140] Since the top surface of mold 21a includes only one mold ramp 212a, mold 21a can include only one molding space 211a recessed inward from the top surface of mold 21a. Therefore, according to another embodiment of the invention, mold 21a may not include a partition wall, and no bridges will be formed on the battery casing 13a manufactured by molding the soft film 135.

[0141] When the soft film 135 is fixed by the bottom surface of the peeler 22a, the bottom surface of the peeler 22a contacts the top surface of the soft film 135. Therefore, according to another embodiment of the present invention, the peeler 22a may also include only a peeler inclined surface 222a having the same inclination as the inclined surface of the mold 21a, and may also include a plurality of peeler horizontal surfaces 223a that contact the horizontal surface of the mold 21a and extend from both ends of the peeler inclined surface 222a.

[0142] According to another embodiment of the invention, since the mold 21a includes only one forming space 211a, the punch 23a may also include only one molding portion 231a into which the soft film 135 is inserted. Furthermore, since the mold 21a does not include a partition wall, no groove for inserting a partition wall is formed even in the punch 23a.

[0143] Figure 19 This is a schematic diagram showing the state of the stripper 22a in a lowered position according to another embodiment of the present invention.

[0144] When the soft film 135 is placed on the top surface of the mold 21a (S901), as Figure 19As shown, the peeler 22 descends (S902). When the top surface of the soft film 135 contacts the bottom surface of the peeler 22, the peeler 22 and the mold 21 come into contact with each other with the soft film 135 therebetween. Furthermore, the peeler 22 presses the soft film 135 upward to fix the soft film 135.

[0145] According to another embodiment of the invention, since the mold 21a includes only one mold ramp 212a and the peeler 22a includes only one peeler ramp 222a, only one inclined region of the soft film 135 can be formed. Furthermore, since the mold 21a includes multiple mold horizontal surfaces 213a and the peeler 22a includes multiple peeler horizontal surfaces 223a, multiple horizontal regions of the soft film 135 can be formed.

[0146] Figure 20 This is a schematic diagram showing the state of the punch 23a descending according to another embodiment of the present invention.

[0147] like Figure 20 As shown, when the peeler 22a secures the soft-pack film 135, the punch 23a descends in a direction inclined relative to the top surface of the mold 21a, specifically the mold ramp 212a (S903). Therefore, the punch 23a is inserted into the forming space 211a containing the soft-pack film 135, and the soft-pack film 135 is stretched (S903). Thus, the soft-pack film 135 can be molded to form a cup portion 133a (S904). Subsequently, when the punch 23a and the peeler 22a rise again, the soft-pack film 135 in which the cup portion 133a is formed can be removed, thereby manufacturing a soft-pack battery casing 13a according to an embodiment of the present invention.

[0148] According to another embodiment of the invention, the molding portion 231a of the punch 23a can be inserted into the forming space 211a of the mold 21a to stretch the soft film 135, thereby forming a cup portion 133a in the first housing 131, but the cup portion may not be formed in the second housing 132.

[0149] Figure 21 This is a partially enlarged view showing the stamped edge 1334a of the cup portion 133a according to another embodiment of the present invention.

[0150] like Figure 21 As shown, although the outer wall 1333a of the cup portion 133a itself is formed to have an inclination, according to an embodiment of the invention, the bottom 1332a of the cup portion 133a is also formed to have an inclination. Therefore, the inclination angle b between the bottom 1332a of the cup portion 133a and the outer wall 1333a can be further reduced to be nearly vertical, so as to have an inclination angle b between about 90° and about 95°, and further, between 90° and 93°.

[0151] Reference Figure 1 , Figure 14 and Figure 16 According to an embodiment of the present invention, the battery housing includes: a cup portion 133 formed in at least one of a first housing 131 or a second housing 132 and having an outer wall 1333 along an edge of a surface of a bottom 1332, thereby providing a receiving space for an electrode assembly; and a folding portion 139 folded at an edge of the cup portion 133 to integrally connect the first housing 131 to the second housing 132.

[0152] The outer wall 1333 may include: a first outer wall formed on one side of a fold 139 on the edge of a surface of the bottom 1332; a second outer wall formed on the opposite side of the first outer wall; a third outer wall formed to connect the first outer wall to the second outer wall; and a fourth outer wall formed on the opposite side of the third outer wall, and the inward tilt angle between the first outer wall and the bottom 1332 may be formed in the range of 90° to 95°.

[0153] Here, fold 139 refers to a bridge portion corresponding to the partition wall 215 that can be formed when the device for molding the soft pack includes the partition wall 215, and this bridge portion can be a reference portion when the battery casing 13 is subsequently folded. That is, when the secondary battery 1 is manufactured, the bridge portion will have a fold 139 formed on one side of the secondary battery 1, so it can also be understood that the fold 139 is formed on one side of the bridge portion in the edge of one surface of the bottom 1332.

[0154] However, when the cup portion 133a is formed only in one of the first housing 131 or the second housing 132, there is no separate bridge portion. In this case, it can be understood that the first outer wall is formed on one side of the fold in the edge of one surface of the bottom.

[0155] Therefore, the inclination angle α of the bottom 1332 of the first outer wall (which is the outer wall of the cup portion 133 formed on the side of the fold 139) can be further reduced to be formed as close to vertical, thereby the electrode assembly can be set very close to the outer wall of the cup portion to reduce the unnecessary volume of the cup portion.

[0156] The inward inclination angle between the second outer wall and the bottom 1332 can be greater than the inward inclination angle α between the first outer wall and the bottom 1332.

[0157] In addition, the inward inclination angle between the second outer wall and the bottom 1332 can be more than 10° larger than the inward inclination angle α between the first outer wall and the bottom 1332.

[0158] It will be understood by those skilled in the art that this invention can be implemented in other specific forms without altering the technical concept or essential characteristics. Therefore, the embodiments disclosed above are considered illustrative rather than restrictive. Consequently, the scope of this invention is defined by the appended claims, rather than by the exemplary embodiments described above and therein. Various modifications made within the meaning of equivalents to the claims and within the scope of the claims are considered to be within the scope of this invention.

[0159] [Figure Labels]

[0160] 1: Secondary battery 2: Molding device

[0161] 10: Electrode assembly 11: Electrode connector

[0162] 12: Electrode leads 13: Battery casing

[0163] 14: Insulation part 15: Bat ears

[0164] 21: Mold 22: Peeler

[0165] 23: Punch 111: Positive terminal connector

[0166] 112: Negative terminal piece; 121: Positive terminal lead

[0167] 122: Negative lead; 131: First housing

[0168] 132: Second shell 133: Cup portion

[0169] 134: Edge; 135: Soft wrapping film

[0170] 136: Bridge section; 137: Degassing section

[0171] 139: Folding section; 211: Forming space

[0172] 212: Sloping surface of the mold 213: Horizontal surface of the mold

[0173] 214: Inner wall; 215: Partition wall

[0174] 221: Penetration section; 222: Peeler bevel.

[0175] 223: Peeler horizontal plane; 231: Molding section

[0176] 232: Outer wall; 1331: Accommodation space

[0177] 1332: Bottom 1333: Outer Wall

[0178] 1334: Stamped edge; 1351: Sealant layer

[0179] 1352: Moisture barrier layer; 1353: Surface protective layer

[0180] 2111: First molding space; 2112: Second molding space

[0181] 2121: First mold inclined surface; 2122: Second mold inclined surface

[0182] 2151: Reinforcing section; 2221: First peeler inclined surface

[0183] 2222: Second peeler inclined surface; 2311: First molding section

[0184] 2312: Second Molding Department

Claims

1. An apparatus for molding a battery casing, the apparatus comprising: A mold having a top surface, a soft film disposed on the top surface, and the mold including at least one molding space formed to be recessed inward from the top surface; as well as A punch, positioned above the forming space, descends to insert the flexible film into the forming space, thereby molding the flexible film. The top surface of the mold includes at least one mold ramp. The mold inclined surface includes a first mold inclined surface and a second mold inclined surface, and The first mold inclined surface and the second mold inclined surface are formed symmetrically to each other. The first mold inclined surface and the second mold inclined surface have a downward slope as they approach each other. The forming space includes: A first molding space is formed as an indentation extending from the first mold inclined surface into the mold; and The second molding space is formed as an indentation from the inclined surface of the second mold towards the interior of the mold. The mold also includes a partition wall formed between the first molding space and the second molding space. The partition wall has a thickness that gradually increases towards its lower portion, and The inner wall of the molded space formed by the partition wall has an inclination.

2. The apparatus according to claim 1, wherein, The die slope has an inclination that slopes in the direction in which the punch descends.

3. The apparatus according to claim 1, wherein, The molding space is formed as an indentation from the mold slope toward the interior of the mold.

4. The apparatus according to claim 1, wherein, The punch has a groove at a position corresponding to the partition wall, into which the partition wall is inserted.

5. The apparatus according to claim 1, wherein, The punch includes: A first molding section is configured to insert the flexible film into the first molding space; and The second molding section is configured to insert the soft film into the second molding space.

6. The apparatus according to claim 1, wherein, The mold also includes a mold horizontal plane that extends from at least one end of the mold ramp and is perpendicular to the direction of the punch's descent.

7. The apparatus according to claim 1, wherein, In the punch, the molding portion that is in direct contact with the soft film has the same inclination as the mold slope.

8. The apparatus of claim 1, further comprising a peeler disposed above the mold, descending to contact the mold in the presence of the soft film between the peeler and the mold, and configured to secure the soft film.

9. The apparatus according to claim 8, wherein, The bottom surface of the peeler includes at least one peeler slope, which contacts the mold slope and has the same inclination as the mold slope.

10. A method for molding a battery casing using the apparatus of claim 1, the method comprising: The flexible film is placed on the top surface of the mold; This causes the punch, positioned above a molding space that is recessed inward from the top surface of the mold, to descend in a direction inclined relative to at least a portion of the top surface. as well as The flexible film is inserted into the forming space using the punch to form a cup portion in the flexible film.

11. The method according to claim 10, wherein, When the punch is lowered, the top surface of the die includes at least one inclined surface.

12. A battery casing manufactured by the device of claim 1, comprising: A cup portion is formed in at least one of the first housing or the second housing and has an outer wall along an edge of one surface of the bottom, thereby providing a receiving space for the electrode assembly; as well as A folding section is provided on one side of the cup portion to integrally connect the first housing to the second housing. The outer wall includes: The first outer wall is formed on one side of the fold on the edge of the one surface at the bottom; The second outer wall is formed on the opposite side of the first outer wall; A third outer wall is formed to connect the first outer wall to the second outer wall; and The fourth outer wall is formed on the opposite side of the third outer wall. The inward inclination angle between the first outer wall and the bottom is formed in the range of 90° to 95°.

13. The battery casing according to claim 12, wherein, The inward inclination angle between the second outer wall and the bottom is greater than the inward inclination angle between the first outer wall and the bottom.

14. The battery casing according to claim 13, wherein, The inward inclination angle between the second outer wall and the bottom is formed to be more than 10° larger than the inward inclination angle between the first outer wall and the bottom.

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