Pouch-type secondary battery

Abstract

According to an embodiment of the present invention, a pouch battery housing includes: an electrode assembly formed by stacking electrodes and a separator; a pouch battery housing having a cup portion therein for receiving the electrode assembly, wherein the pouch battery housing includes a side extending to the outer side of the cup portion, the side including: a sealing portion disposed on the opposite outer side and sealed; and a non-sealing portion disposed on the opposite inner side and not sealed, and the side is not adhered to the cup portion, and the side is folded at the non-sealing portion.

Description

Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2020-0104225, filed on August 19, 2020, and Korean Patent Application No. 10-2021-0074474, filed on June 8, 2021, the contents of which are incorporated herein by reference. Technical Field

[0004] The present invention relates to a pouch-type secondary battery, and more specifically, to a pouch-type secondary battery in which the sides do not adhere to the cup when the sides are folded, and the holding force of the sides is increased to maintain the folded state. Background Technology

[0005] Typically, rechargeable batteries include nickel-cadmium batteries, nickel-metal hydride batteries, lithium-ion batteries, and lithium-ion polymer batteries. Such rechargeable batteries are suitable for small products such as digital cameras, P-DVD players, MP3 players, mobile phones, PDAs, portable gaming devices, power tools, and electric bicycles, as well as large products requiring high power, such as electric vehicles and hybrid vehicles, energy storage devices for storing surplus electricity or renewable energy, and backup energy storage devices.

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

[0007] Depending on the material of the casing housing the electrode assembly, such secondary batteries are classified into pouch-type secondary batteries and can-type secondary batteries. In pouch-type secondary batteries, the electrode assembly is housed in a pouch made of a flexible polymer material. In can-type secondary batteries, the electrode assembly is housed in a casing made of metal or plastic.

[0008] The soft-pack, which serves as the casing of a pouch-type secondary battery, is manufactured by pressure processing a flexible soft-pack film to form a cup. Furthermore, during the formation of the cup, electrode assemblies are housed within the cup's receiving space, and then the edges of the cup are sealed to manufacture the secondary battery.

[0009] In this pressure processing, stretching is performed by inserting the flexible film into a molding device such as a pressurizing equipment and applying pressure to the flexible film using a punch to stretch it. The flexible film is configured as a multi-layered structure, with a moisture barrier layer made of metal disposed within the film. However, according to the prior art, the metal of the moisture barrier layer in the aluminum alloy has a large crystal grain size, and the moisture barrier layer has a relatively thin thickness. Therefore, when the sides are folded to reduce the energy density relative to the volume, the sides are not fixed and are then unfolded at a predetermined angle. Consequently, when the tape is individually adhered to the sides, there is a problem of increased overall thickness of the secondary battery due to the thickness of the tape itself. Furthermore, since an additional step of adhering tape is required after the step of folding the sides, there is a problem of increased number of steps and reduced productivity of the secondary battery.

[0010] As prior art, it has Japanese Patent Registration No. 6022956. Summary of the Invention

[0011] Technical issues

[0012] One object of the present invention is to provide a pouch-type secondary battery in which the side does not adhere to the cup portion even when the side is folded, and the holding force of the side is increased to maintain the folded state.

[0013] The objectives of this invention are not limited to those described above, and those skilled in the art will clearly understand other unmentioned objectives through the following description.

[0014] Technical solution

[0015] A pouch-type secondary battery according to an embodiment of the present invention for achieving the above-described objectives includes: an electrode assembly in which electrodes and separators are stacked; a pouch-type battery housing including a cup portion configured to receive the electrode assembly, wherein the pouch-type battery housing includes a side extending to the outside of the cup portion, and the side portion includes: a sealing portion disposed on an opposite outer side and sealed; and a non-sealing portion disposed on an opposite inner side and not sealed, wherein the side portion is not adhered to the cup portion, and the side portion is folded at the non-sealing portion.

[0016] Additionally, the side can contact the outer wall of the cup and be folded.

[0017] Additionally, the side can be folded at an angle of 85° to 95°.

[0018] Additionally, the side may include: a first fold portion folded at a position relatively close to the outer end; and a second fold portion folded at a position relatively close to the cup portion.

[0019] Furthermore, the first fold portion may be disposed on the sealing portion, and the second fold portion may be disposed on the non-sealing portion.

[0020] Furthermore, the side can be folded at an angle of 170° to 180° relative to the first fold.

[0021] Furthermore, the side can be folded at an angle of 85° to 95° relative to the second fold.

[0022] Furthermore, the side can be folded at an angle of 88° to 92° relative to the second fold.

[0023] Furthermore, the battery casing can be manufactured by molding a soft-pack film, which may include: a sealant layer made of a first polymer and formed at the innermost layer; a surface protective layer made of a second polymer and formed at the outermost layer; and a moisture barrier layer stacked between the surface protective layer and the sealant layer, wherein the moisture barrier layer may be formed as an aluminum alloy film with a thickness of 50 μm to 80 μm and a particle size of 10 μm to 13 μm, and the sealant layer may have a thickness of 60 μm to 100 μm.

[0024] In addition, the aluminum alloy film may include AA8021 aluminum alloy.

[0025] In addition, the aluminum alloy film may contain 1.3 wt% to 1.7 wt% iron and less than 0.2 wt% silicon.

[0026] In addition, the thickness of the moisture barrier layer can be from 55 μm to 65 μm.

[0027] The thickness of the sealant layer can be from 75 μm to 85 μm.

[0028] Furthermore, the pouch battery casing may further include an elongated auxiliary layer made of a third polymer and stacked between the surface protective layer and the moisture barrier layer.

[0029] Furthermore, the thickness of the elongation auxiliary layer can be from 20 μm to 50 μm.

[0030] The surface area of ​​the electrode assembly can be 15000 mm². 2 Up to 100,000 mm 2 .

[0031] Further specific details of the embodiments are included in the detailed description and accompanying drawings.

[0032] Beneficial effects

[0033] According to embodiments of the present invention, at least the following effects are achieved.

[0034] Even when the sides are folded, the sides may not adhere to the cup, but the holding force of the sides can be increased to maintain the folded state.

[0035] Furthermore, when the side is folded toward the cup, it can be folded at an angle of 85° to 95°, preferably at an angle of 88° to 92°, thereby reducing the unnecessary volume of the secondary battery.

[0036] The effects of the present invention are not limited to the above description, and therefore this specification contains a variety of other effects. Attached Figure Description

[0037] Figure 1 This is an assembly diagram of the secondary battery 1 according to an embodiment of the present invention;

[0038] Figure 2 This is a cross-sectional view of the soft film 135 according to an embodiment of the present invention;

[0039] Figure 3 This is a graph showing the iron and silicon content of aluminum alloys with alloy number AA8079 and AA8021.

[0040] Figure 4 This is a graph showing the tensile strength, elongation, and grain size of aluminum alloys with iron and silicon content based on alloy number AA8079 and alloy number AA8021.

[0041] Figure 5 These are magnified SEM images of crystals from aluminum alloys with alloy number AA8079 and AA8021.

[0042] Figure 6 This is a schematic diagram of the molding apparatus 2 according to an embodiment of the present invention;

[0043] Figure 7 This is an enlarged schematic diagram of the cup portion 333 and the bridge 336 based on the prior art;

[0044] Figure 8 This is an enlarged schematic diagram of the cup portion 133 and the bridge 336 according to an embodiment of the present invention;

[0045] Figure 9 This is an enlarged schematic diagram of the cup portion 133 and the degassing portion 137 according to an embodiment of the present invention.

[0046] Figure 10 This is a schematic top view showing the state in which the electrode assembly 10 according to an embodiment of the present invention is housed in the cup portion 133;

[0047] Figure 11 This is a schematic diagram of corner 364 based on existing technology;

[0048] Figure 12 This is a schematic diagram illustrating corner 164 according to an embodiment of the present invention;

[0049] Figure 13 This is a schematic diagram showing the folded state of the battery casing 13 according to an embodiment of the present invention;

[0050] Figure 14 This is a schematic diagram showing the folded state of the battery casing 13 according to an embodiment of the present invention;

[0051] Figure 15 This is an enlarged view of the groove 1391 formed in the battery casing 13 according to an embodiment of the present invention;

[0052] Figure 16 This is an enlarged schematic diagram of the cup portion 133 and the mold edge 1621 according to another embodiment of the present invention;

[0053] Figure 17 This is a schematic diagram showing the folded state of the battery casing 13a according to another embodiment of the present invention;

[0054] Figure 18 This is a schematic diagram showing the folded state of the battery casing 13a according to another embodiment of the present invention;

[0055] Figure 19 This is an enlarged view of the groove 1391a formed in the battery casing 13 according to another embodiment of the present invention;

[0056] Figure 20 This is a schematic top view showing the state of the battery casing 33 before the degassing portion 337 is cut, according to the prior art;

[0057] Figure 21 This is a schematic top view showing the state of the battery casing 13 before the degassing portion 137 is cut according to an embodiment of the present invention;

[0058] Figure 22 This is a block diagram of the inspection device 4 according to an embodiment of the present invention;

[0059] Figure 23 This is a schematic diagram showing the state in which the degassing portion 137 of the battery casing 13 according to an embodiment of the present invention is cut to complete the manufacturing of the secondary battery 1;

[0060] Figure 24 This is a schematic side view showing the state of the side 334 folded according to the prior art;

[0061] Figure 25This is a schematic top view showing the state of the side 334 folded according to the prior art;

[0062] Figure 26 This is a schematic side view showing the folded state of side 334 according to an embodiment of the present invention;

[0063] Figure 27 This is a schematic diagram of battery module 5 according to an embodiment of the present invention;

[0064] Figure 28 This is a magnified front view showing the state in which the secondary battery 3 is housed in the housing 51 of the battery module 5 according to the prior art;

[0065] Figure 29 This is a side enlarged view showing the state in which the secondary battery 3 is housed in the housing 51 of the battery module 5 according to the prior art;

[0066] Figure 30 This is a front enlarged view showing the state in which the secondary battery 1 is housed in the housing 51 of the battery module 5 according to an embodiment of the present invention;

[0067] Figure 31 This is a side enlarged view showing the state in which the secondary battery 1 is housed in the housing 51 of the battery module 5 according to an embodiment of the present invention. Detailed Implementation

[0068] The advantages and features of the present invention, as well as methods for implementing them, will become apparent from the embodiments described below in conjunction with the accompanying drawings. However, the invention is not limited to the embodiments disclosed below, but can be implemented in various different forms. These embodiments are, of course, intended to make this disclosure more complete and comprehensive, and to fully inform those skilled in the art of the field of the invention. Furthermore, the invention is defined only by the scope of the claims. The same reference numerals refer to the same elements.

[0069] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the meanings commonly understood by one of ordinary skill in the art to which this invention pertains. Furthermore, unless specifically stated in the description, terms as defined in commonly used dictionaries should not be ideally or over-interpreted as having a formal meaning.

[0070] In the following description, the terminology is for illustrative purposes only and is not intended to limit the invention. In this specification, singular terms may include plural terms unless otherwise stated. "Comprising (including)" and / or "including (containing)" do not exclude other components besides those described.

[0071] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0072] Figure 1This is an assembly diagram of a secondary battery 1 according to an embodiment of the present invention.

[0073] According to an embodiment of the present invention, since the tensile strength and elongation of the soft film 135 can be increased, the toughness can be improved, thereby improving the formability when molding the soft film 135 to manufacture the soft-pack battery casing 13.

[0074] Therefore, the soft film 135 according to an embodiment of the present invention includes: a sealant layer 1351 made of a first polymer and formed at the innermost layer (see reference). Figure 2 ); a surface protective layer 1353 made of a second polymer and formed on the outermost layer (see reference). Figure 2 ); and a moisture (or gas) barrier layer 1352 stacked between the surface protective layer 1353 and the sealant layer 1351 (see reference 1352). Figure 2 The moisture barrier layer 1352 can be formed as an aluminum alloy film with a thickness of 50 μm to 80 μm and a particle size of 10 μm to 13 μm, and the sealant layer 1351 can have a thickness of 60 μm to 100 μm. In particular, the thickness of the moisture barrier layer 1352 can be 55 μm to 65 μm, and the thickness of the sealant layer 1351 can be 75 μm to 85 μm.

[0075] Electrode assembly 10 is constructed by alternately stacking electrodes 101 (e.g., ... Figure 8 (as shown) and partition 102 (refer to) Figure 8 The process involves first coating a slurry containing a mixture of electrode active material, binder, and plasticizer onto a positive current collector and a negative current collector to create electrodes 101, such as positive and negative electrodes. Then, individual separators 102 are stacked between the electrodes 101 to form an electrode assembly 10. The electrode assembly 10 is inserted into a battery casing 13, and an electrolyte is injected to seal the battery casing 13.

[0076] The surface area of ​​the electrode assembly 10 can be 15000 mm². 2 Up to 100,000 mm 2 The total width is obtained by multiplying the total length by the total width. Specifically, the total width of the electrode assembly 10 can be 60 mm or more. Furthermore, the electrode assembly 10 can have a thickness of 6 mm to 20 mm in the stacking direction. Therefore, compared to conventional small batteries, the electrode assembly 10 according to embodiments of the present invention can provide a large battery capacity.

[0077] Specifically, the electrode assembly 10 includes two types of electrodes 101 (e.g., positive and negative electrodes) and a separator 102 inserted between the electrodes 101 to insulate them from each other. The electrode assembly 10 can be stacked, jelly roll-type, stacked folded type, etc. Each of the two types of electrodes 101 (i.e., positive and negative electrodes) has a structure in which an active material slurry is coated onto an electrode current collector having a metal foil or metal mesh shape. The active material slurry is typically formed by stirring granular active materials, conductors, etc., with a solvent added. The solvent can be removed in a subsequent process.

[0078] like Figure 1 As shown, the electrode assembly 10 includes electrode tabs 11. The electrode tabs 11 are connected to the positive and negative electrodes of the electrode assembly 10, respectively, protruding outwards from the electrode assembly 10, thereby providing a path for electron movement between the interior and exterior of the electrode assembly 10. The electrode current collector of the electrode assembly 10 consists of a portion coated with an electrode active material and an uncoated end portion, i.e., an uncoated portion, without electrode active material. Furthermore, each of the electrode tabs 11 can be formed by cutting the uncoated portion, or each of the electrode tabs 11 can be formed by connecting individual conductive members to the uncoated portion via ultrasonic welding. Figure 1 As shown, the electrode tabs 11 may protrude in each of the different directions of the electrode assembly 10, but are not limited thereto. For example, the electrode tabs 11 may protrude in various directions, such as protruding parallel to each other from one side in the same direction.

[0079] In the electrode assembly 10, the electrode lead 12, which supplies power to the external secondary battery 1, is connected to the electrode terminal piece 11 by spot welding. Additionally, a portion of the electrode lead 12 is surrounded by an insulating portion 14. The insulating portion 14 can be configured as a side 134 where the first housing 131 and the second housing 132 of the battery housing 13 are thermally fused, thus bonding the electrode lead 12 to the battery housing 13. Furthermore, this prevents electricity generated from the electrode assembly 10 from flowing through the electrode lead 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 material. Typically, a thin insulating strip that is easily attached to the electrode lead 12 is used as the insulating portion 14, but the invention is not limited to this. For example, various components can be used as the insulating portion 14, as long as the component can insulate the electrode lead 12.

[0080] One end of the electrode lead 12 is connected to the electrode terminal block 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 terminal block 111 and extends in the direction in which the cathode terminal block 111 protrudes; and an anode lead 122, one end of which is connected to the anode terminal block 112 and extends in the direction in which the anode terminal block 112 protrudes. On the other hand, as... Figure 1 As shown, the other ends of all the positive leads 121 and negative leads 122 protrude outwards from the battery casing 13. As a result, the electricity generated in the electrode assembly 10 can be supplied to the outside. Furthermore, since each of the positive terminal piece 111 and the negative terminal piece 112 is formed to protrude in various directions, each of the positive leads 121 and the negative leads 122 can extend in various directions.

[0081] 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 (i.e., aluminum (Al) material), and the anode lead 122 can be made of the same material as the anode current collector (i.e., copper (Cu) material or copper material plated with nickel (Ni)). Furthermore, the portion of the electrode lead 12 that protrudes outward from the battery casing 13 can be configured as a terminal portion and electrically connected to an external terminal.

[0082] The battery housing 13 is a flexible package formed by molding a flexible material and housing the electrode assembly 10 therein. The case where the battery housing 13 is a flexible package will be described below. When using punch 22 (see reference...) Figure 6 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-pack-shaped receiving space 1331, thereby manufacturing a battery casing 13.

[0083] The battery housing 13 accommodates the electrode assembly 10, exposing a portion of the electrode leads 12, which are then sealed. Figure 1 As shown, the battery casing 13 includes a first casing 131 and a second casing 132. A receiving space 1331 may be provided in the first casing 131, and a cup portion 133 is formed in the receiving space 1331 to receive the electrode assembly 10. The second casing 132 may 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.

[0084] When molding the cup portion 133 in the flexible film 135, only one cup portion 133 can be formed in one flexible film 135, but the invention is not limited thereto. For example, two cup portions can be stretched and formed in one flexible film 135 so that they are adjacent to each other. Then, as... Figure 1 As shown, cup portions 133 are formed in the first housing 131 and the second housing 132, respectively. Here, each of the cup portions 133 formed in the first housing 131 and the second housing 132 may have the same depth D, but is not limited thereto, and may have different depths D.

[0085] According to an embodiment of the present invention, the depth D of the cup portion 133 can be 3 mm or greater, specifically 6.5 mm or greater. Therefore, compared to a typical small battery, the cup portion 133 according to an embodiment of the present invention can accommodate an electrode assembly 10 with a larger electrode capacity.

[0086] After the electrode assembly 10 is housed 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 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 houses the electrode assembly 10 from above. Therefore, since two cup portions 133 house one electrode assembly 10, a thicker electrode assembly 10 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 sides 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.

[0087] 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, and thus a degassing process for discharging the gas to the outside is performed. The degassing portion 137 will be described in detail later.

[0088] When the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and the insulation portion 14 is formed on a portion 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. Then, an electrolyte is injected into the receiving space, and the side 134 extending outside the cup portion 133 of each of the first housing 131 and the second housing 132 is sealed. The electrolyte allows lithium ions generated by the electrochemical reaction of the electrode 101 during the charging and discharging process of the secondary battery 1 to move. The electrolyte may include a non-aqueous organic electrolyte or a polymer using a high-molecular-weight electrolyte, wherein the non-aqueous organic electrolyte is a mixture of lithium salt and a high-purity organic solvent. Furthermore, the electrolyte may include a sulfide-based solid electrolyte, an oxide-based solid electrolyte, or a polymer-based solid electrolyte, and the solid electrolyte may have flexibility that allows it to be easily deformed by external force. Using the above method, a pouch-type secondary battery 1 can be manufactured.

[0089] Figure 2 This is a cross-sectional view of the soft film 135 according to an embodiment of the present invention.

[0090] The soft-pack of the battery casing 13 of the soft-pack secondary battery 1 according to an embodiment of the present invention can be manufactured by stretching the soft-pack film 135. That is, the battery casing 13 is manufactured by stretching the soft-pack film 135 using a punch 22 or the like to form a cup portion 133. According to an embodiment of the present invention, as Figure 2 As shown, the flexible film 135 may include a sealant layer 1351, a moisture barrier layer 1352, and a surface protective layer 1353, and may also include an elongation auxiliary layer 1354 if necessary.

[0091] The sealant layer 1351 can be made of a first polymer and can be formed at the innermost layer to directly contact the electrode assembly 10. Here, the innermost layer refers to the last layer formed when aligned with the moisture barrier layer 1352 in the direction opposite to the direction in which the electrode assembly 10 is disposed. The battery casing 13 can be manufactured simultaneously by stretching a portion of the pouch film 135 with the stacked structure described above to form a cup portion 133 including a pouch-shaped receiving space 1331 when stretching the pouch film 135 with the stacked structure described above using a punch 22 or the like. Furthermore, when the electrode assembly 10 is housed in the receiving space 1331, an electrolyte is injected. Then, when the first casing 131 and the second casing 132 are in contact with each other and facing each other, and hot pressing is applied to the sides 134, the sealant layer 1351 is bonded to each other, thereby sealing the pouch. Here, since the sealant layer 1351 is in direct contact with the electrode assembly 10, the sealant layer 1351 must be insulating. Furthermore, because the sealant layer 1351 is in contact with the electrolyte, it must be corrosion-resistant. Additionally, 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 is essential. That is, the sides 134 where the sealant layers 1351 are joined together should have excellent thermal bonding strength. Typically, the first polymer forming the sealant layer 1351 can include one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(p-benzobisoxazole), polyarylate, polytetrafluoroethylene, and glass fiber. In particular, for the sealant layer, polyolefin resins such as polypropylene (PP) or polyethylene (PE) are used. Polypropylene (PP) possesses 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 sealant layer 1351. Furthermore, sealant layer 1351 can be made from cast polypropylene, acid-modified polypropylene, or a polypropylene-butene-ethylene terpolymer. Here, the acid-treated polypropylene can be maleic anhydride polypropylene (MAHPP). Additionally, 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 each formed as a layer.

[0092] According to embodiments of the present invention, the thickness of the sealant layer 1351 can be from 60 μm to 100 μm, specifically from 75 μm to 85 μm. If the thickness of the sealant layer 1351 is less than 60 μm, there may be a problem of deterioration in the durability of the sealant layer 1351, such as internal damage during sealing. Furthermore, if the thickness of the sealant layer 1351 is greater than 100 μm, the formability may be deteriorated due to the excessive thickness of the entire pouch, or the energy density relative to the volume of the secondary battery 1 may decrease. When the thickness of the sealant layer 1351 is thin, the insulation breakdown voltage of the pouch film 135 may decrease, thus the insulation may deteriorate. When a battery is manufactured using a pouch film 135 with poor insulation, the defect rate may increase.

[0093] 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 pouch, prevent the entry or exit of external gases or moisture into the secondary battery 1, and prevent electrolyte leakage. The moisture barrier layer 1352 can be made of an aluminum alloy film. The aluminum alloy film can ensure a predetermined level or higher of mechanical strength, but is lightweight. Therefore, the aluminum alloy film can complement the electrochemical properties and ensure heat dissipation, in conjunction with the electrode assembly 10 and the electrolyte.

[0094] More specifically, the particle size of the aluminum alloy film according to embodiments of the present invention can be from 10 μm to 13 μm, preferably from 10.5 μm to 12.5 μm, and more preferably from 11 μm to 12 μm. When the particle size of the aluminum alloy film meets the above range, the molding depth can be increased during cup forming without producing pinholes or cracks.

[0095] The aluminum alloy film may include one or two or more of the following materials selected from the group consisting of iron (Fe), copper (Cu), chromium (Cr), manganese (Mn), nickel (Ni), magnesium (Mg) and zinc (Zn), other than aluminum.

[0096] According to existing technology, the thickness of the moisture barrier layer 1352 is approximately 30 μm to approximately 50 μm, particularly 40 μm, thus resulting in poor formability. Therefore, even when the soft film is stretched and molded, the cup portion 333 (refer to...) Figure 7 The depth D' of the cup portion 333 can also be increased, so the outer wall 338 of the cup portion 333 (refer to...) Figure 7 The formation of an approximately vertical position is restricted. Furthermore, the edge 36 of the cup portion 333 (refer to...) Figure 7 There are also limitations to reducing the radius of curvature of the battery casing. Furthermore, when the battery casing is subjected to external impacts, the internal electrode components may be easily damaged due to weak perforation strength.

[0097] To address this issue, increasing the thickness of the moisture barrier layer 1352 to approximately 80 μm or more not only increases manufacturing costs but also makes the overall thickness of the pouch excessive. Consequently, the energy density relative to the volume of the secondary battery 1 deteriorates. Conversely, reducing the thickness of the sealant layer 1351 to less than 60 μm to decrease the overall thickness of the pouch results in reduced seal durability, as described above.

[0098] According to an embodiment of the present invention, the thickness of the moisture barrier layer 1352 can be from 50 μm to 80 μm, specifically from 55 μm to 65 μm. Therefore, the formability of the moisture barrier layer 1352 can be improved. When the soft film 135 is stretched and formed, the depth D of the cup portion 133 can be formed to a greater depth, and the outer wall 138 of the cup portion 133 can be formed in an approximately vertical state. Therefore, the edge 16 of the cup portion 133 (refer to...) Figure 8 The radius of curvature R2 of the secondary battery can be reduced. Therefore, due to the increase in the volume of the housing space 1331, the volume of the electrode assembly 10 housed in the housing space 1331 also increases, and the energy efficiency of the secondary battery 1 relative to its volume also increases. Furthermore, the manufacturing cost does not increase significantly, the total thickness of the pouch can be not significantly increased without reducing the thickness of the sealant layer 1351, and the sealing durability does not deteriorate.

[0099] Furthermore, due to the improved perforation strength of the soft membrane, the electrode assembly 10 within the soft membrane can be more effectively protected even if it is damaged by external pressure or puncture by a sharp object. Here, excellent perforation strength refers to high strength when perforated in the soft membrane 135.

[0100] However, while increasing the thickness of the aluminum alloy film can increase the molding depth, it can also create small holes or cracks in the molded aluminum alloy film, thereby degrading the sealing durability.

[0101] Through repeated research, the inventors discovered that when an aluminum alloy film with a specific particle size is used as the material for the moisture barrier layer, and when the thickness of each of the moisture barrier layer and the sealant layer is controlled within a specific range, the cup portion is molded deeper, and the sealing durability is well maintained. Therefore, this invention was completed.

[0102] Specifically, the moisture barrier layer 1352 according to the present invention comprises an aluminum alloy film with a particle size of 10 μm to 13 μm, preferably 10.5 μm to 12.5 μm, and more preferably 11 μm to 12 μm. When the particle size of the aluminum alloy film meets the above range, the molding depth can be increased during cup molding without producing pinholes or cracks. When the particle size of the aluminum alloy film exceeds 13 μm, the strength of the aluminum alloy film decreases, and the generation of cracks or pinholes increases due to the difficulty in dispersing internal stress during stretching. When the particle size is less than 10 μm, the flexibility of the aluminum alloy film decreases, and there are limitations to improving formability.

[0103] Meanwhile, the particle size varies depending on the composition and processing method of the aluminum alloy film. Here, a scanning electron microscope (SEM) can be used to observe and measure the cross-section of the aluminum alloy film in the thickness direction. Specifically, in this invention, a scanning electron microscope can be used to obtain the cross-section of the aluminum alloy film in the thickness direction, and then the maximum diameter of a predetermined number of grains observed through the SEM image can be measured, with the average value of the maximum diameters taken as the particle size.

[0104] The surface protective layer 1353, made of a second polymer, is formed on the outermost layer to protect the secondary battery 1 from friction and impact with the outside, and also to electrically insulate the electrode assembly 10 from the outside. Here, the outermost layer refers to the last layer formed when aligned with the moisture barrier layer 1352 in the direction opposite to the direction in which the electrode assembly 10 is disposed. The second polymer forming the surface protective layer 1353 may include one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(terephthalamide), 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 each formed as layers.

[0105] According to embodiments of the present invention, the thickness of the surface protective layer 1353 can be from 5 μm to 25 μm, specifically from 7 μm to 12 μm. If the thickness of the surface protective layer 1353 is less than 5 μm, there may be a problem of external insulation degradation. Conversely, if the thickness of the surface protective layer 1353 is greater than 25 μm, the entire pouch is too thick, and therefore the energy density relative to the volume of the secondary battery 1 may be reduced.

[0106] Although PET is inexpensive, durable, and has excellent electrical insulation properties, its bonding strength is weaker than that of aluminum, which is frequently used for the moisture barrier layer 1352, and its performance may differ when stretched under stress. Therefore, when the surface protective layer 1353 and the moisture barrier layer 1352 are directly bonded to each other, they may peel off during the stretching process. As a result, the moisture barrier layer 1352 is not stretched uniformly, leading to deterioration in formability.

[0107] According to one embodiment of the present invention, the battery casing 13 may be made of a third polymer and further includes an elongation auxiliary layer 1354 stacked between the surface protective layer 1353 and the moisture barrier layer 1352. The elongation auxiliary layer 1354 may be stacked between the surface protective layer 1353 and the moisture barrier layer 1352 to prevent the surface protective layer 1353 and the moisture barrier layer 1352 from peeling off when stretched. The third polymer forming the elongation auxiliary layer 1354 may include one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(terephthalamide), polyarylate, polytetrafluoroethylene, and glass fiber. Specifically, nylon resin is primarily used because it readily adheres to the polyethylene terephthalate (PET) of the surface protective layer 1353 and exhibits similar behavior to the aluminum alloy of the moisture barrier layer 1352 during stretching. Furthermore, the elongation aid layer 1354 can have a single-layer structure made of one material or a composite layer structure formed from two or more materials, each as a layer.

[0108] In the prior art, the thickness of the moisture barrier layer 1352 is approximately 40 μm, therefore the thickness of the elongation auxiliary layer 1354 is quite thin, approximately 15 μm. That is, the thickness ratio of the elongation auxiliary layer to the moisture barrier layer is 1:2.67, which is a relatively high thickness ratio for the moisture barrier layer. However, as described above, according to the embodiment of the present invention, since the thickness of the moisture barrier layer 1352 is approximately 50 μm to approximately 80 μm, specifically 55 μm to 65 μm, the formability of the moisture barrier layer 1352 is improved. Here, in order to also improve the formability of the elongation auxiliary layer 1354, the thickness of the elongation auxiliary layer 1354 can be 20 μm to 50 μm, specifically 25 μm to 38 μm. If the thickness of the elongation auxiliary layer 1354 is less than 20 μm, the elongation auxiliary layer 1354 may not be able to meet the improved formability of the moisture barrier layer 1352 and may be damaged during stretching. On the other hand, if the thickness of the sealant layer 1343 is greater than 50 μm, the total thickness of the pouch is very thick, increasing the volume of the secondary battery 1 and thus reducing the energy density. Specifically, according to embodiments of the present invention, the thickness ratio of the elongation auxiliary layer 1354 to the moisture barrier layer 1352 can be less than 1:2.5. That is, the thickness ratio of the elongation auxiliary layer 1354 can be further increased than that of the elongation auxiliary layer 1354 according to the prior art. However, when the thickness of the elongation auxiliary layer 1354 is too thick, the total thickness of the pouch becomes too thick; therefore, the thickness ratio can be greater than 1:1.5 to avoid the total thickness of the pouch becoming too thick. That is, the thickness ratio can be from 1:1.5 to 1:2.5.

[0109] Figure 3 This is a graph showing the iron and silicon content of aluminum alloys with alloy number AA8079 and AA8021.

[0110] As described above, the particle size of the aluminum alloy film forming the moisture barrier layer 1352 can be from 10 μm to 13 μm, preferably from 10.5 μm to 12.5 μm, and more preferably from 11 μm to 12 μm.

[0111] Furthermore, the iron (Fe) content of the aluminum alloy film can be from 1.2 wt% to 1.7 wt%, preferably from 1.3 wt% to 1.7 wt%, and more preferably from 1.3 wt% to 1.45 wt%. If the iron (Fe) content in the aluminum alloy film is less than 1.2 wt%, the strength of the aluminum alloy film will decrease, and cracks and pinholes will occur during the forming process. If the iron (Fe) content exceeds 1.7 wt%, the flexibility of the aluminum alloy film will decrease, resulting in limitations on improving formability.

[0112] In addition, the silicon (Si) content of the aluminum alloy film can be 0.2 wt% or less, preferably 0.05 wt% to 0.2 wt%, and more preferably 0.1 wt% to 0.2 wt%. When the silicon content exceeds 0.2 wt%, the formability may deteriorate.

[0113] Specifically, the aluminum alloy film according to the present invention can be an aluminum alloy having alloy number AA8021.

[0114] On the other hand, the aluminum alloy film with alloy number AA8079 is mainly used in battery pouches according to existing technology. When the aluminum alloy contains a large amount of iron, the mechanical strength is improved; when the aluminum alloy contains a small amount of iron, the flexibility is improved.

[0115] like Figure 3 As shown, the aluminum alloy with alloy number AA8079 (hereinafter referred to as AA8079 aluminum alloy) contains 0.6 wt% to 1.2 wt% iron and less than 0.3 wt% silicon. In the case of aluminum alloy with alloy number AA8079, the relatively small amount of iron content can improve flexibility when using this aluminum alloy to manufacture moisture barrier layer 1352, but the strength will be reduced, which may limit the formability.

[0116] On the other hand, such as Figure 3 As shown, AA8021 aluminum alloy may contain 1.2wt% to 1.7wt% iron, specifically 1.3wt% to 1.7wt% iron, and less than 0.2wt% silicon. When using AA8021 aluminum alloy to manufacture moisture barrier layer 1352, the relatively high iron content can improve tensile strength, elongation, and puncture strength.

[0117] On the other hand, when a tensile force is applied to any material, the relationship between tensile strength and elongation can be represented as a curve. In this case, if the vertical axis of the curve represents tensile strength and the horizontal axis represents elongation, then the area under the curve represents the toughness of the corresponding material. Toughness refers to the degree to which a material resists fracture; the higher the toughness, the longer the material can be stretched until it breaks.

[0118] Therefore, when using AA8021 aluminum alloy to manufacture the moisture barrier layer 1352, the tensile strength and elongation can be improved, thereby improving toughness and formability.

[0119] Figure 4 This is a graph showing the tensile strength, elongation, and grain size of AA8079 and AA8021 aluminum alloys as a function of varying iron and silicon content. Figure 5 These are magnified SEM images of the grains of AA8079 and AA8021 aluminum alloys.

[0120] like Figure 4As shown, tensile strength, elongation, and grain size change depending on the iron content of the aluminum alloy. Specifically, since tensile strength and elongation are directly proportional to iron content, they increase with increasing iron content. On the other hand, since grain size is inversely proportional to iron content, it decreases with increasing iron content.

[0121] AA8079 aluminum alloy has a relatively large grain size of 13μm to 21μm. Therefore, the following problem exists: due to the less dispersion of internal stress during stretching, the number of pores increases, and the formability of the battery casing 13 decreases.

[0122] AA8021 aluminum alloy has a small grain size of 10μm to 13μm. Therefore, due to the greater dispersion of internal stress during stretching, the number of pores can be reduced, thereby improving the formability of the battery casing 13.

[0123] The pouch-type battery casing 13, manufactured by molding a pouch film 135 with a moisture barrier layer 1352, can have improved formability, allowing for a deeper cup portion 133 depth D, a more vertical outer wall 138 for the cup portion 133, and a smaller radius of curvature for the edge 16 of the cup portion 133, thereby accommodating larger and thicker electrode assemblies 10. Therefore, the energy efficiency of the secondary battery 1 manufactured with the battery casing 13 relative to its volume can be increased.

[0124] The total thickness of the flexible film 135 according to the present invention can be from 160 μm to 200 μm, preferably from 180 μm to 200 μm. When the thickness of the flexible film 135 meets the above range, the reduction in battery housing space and the deterioration of sealing durability caused by the increase in the thickness of the flexible film can be minimized while increasing the molding depth.

[0125] The flexible film 135 according to the invention, comprising an aluminum alloy film having a specific thickness and particle size, exhibits excellent tensile strength and elongation. Specifically, when the flexible film according to the invention is cut to a size of 15mm × 80mm, the tensile strength measured while stretching at a stretching speed of 50mm / min can be from 200N / 15mm to 300N / 15mm, preferably from 210N / 15mm to 270N / 15mm, more preferably from 220N / 15mm to 250N / 15mm, and the elongation can be from 120% to 150%, preferably from 120% to 140%, more preferably from 120% to 130%. As described above, the flexible film stack according to the invention has high tensile strength and elongation, thus improving toughness. During cup molding, even with deep molding depth, the possibility of crack formation is low.

[0126] Furthermore, the flexible film stack according to the present invention exhibits excellent perforation strength by comprising an aluminum alloy film having a specific thickness and particle size. Specifically, the perforation strength of the flexible film stack according to the present invention can be 30 N or higher.

[0127] Figure 6 This is a schematic diagram of the molding apparatus 2 according to an embodiment of the present invention.

[0128] According to an embodiment of the present invention, a molding apparatus 2 for molding a flexible film 135 includes: a mold 21 on which the flexible film 135 is placed on the top surface of the mold 21; and a punch 22 disposed above the mold 21 and descending to press the flexible film 135. Furthermore, the mold 21 includes a molding portion 211 recessed inward from the top surface, and the punch 22 forms a cup portion 133 by inserting the flexible film 135 into the molding portion 211 to stretch and shape the flexible film 135.

[0129] According to an embodiment of the present invention, when molding the soft film 135 using the molding apparatus 2, such as Figure 6 As shown, the mold 21 has two adjacent molding portions 211 and a partition wall 212 formed between the two molding portions 211. When the punch 22 is inserted into the two molding portions 211 to stretch and shape the soft film 135, a cup portion can be formed in each of the first housing 131 and the second housing 132 to correspond to each of the two molding portions 211, resulting in a total of two cup portions 133. Furthermore, a bridge 136 can be formed between the two cup portions 133 to correspond to the partition wall 212.

[0130] Bridge 136 can be used as a reference part when the battery casing 13 is folded later. When the secondary battery 1 is manufactured, bridge 136 can form a folding part 139 on one side of the secondary battery 1 (see reference). Figure 14 Since the fold 139 integrally connects the first housing 131 and the second housing 132, the number of sides 134 to be sealed can be reduced when a sealing process is performed later. Therefore, processing speed can be increased and the number of sealing processes can be reduced. Here, as the width of the fold 139 decreases, the outer wall 138 of the cup portion 133 (refer to...) Figure 8 The space 17 between the electrode assembly 10 and the electrode assembly 10 (reference) Figure 8 The volume of the secondary battery 1 also decreases, and therefore, because the total volume of the secondary battery 1 decreases, the energy density relative to the volume can increase.

[0131] Because the width of the fold 139 and the thickness t of the bridge 136 (reference) Figure 8The thickness t of the bridge 136 is proportional to the thickness of the partition wall 212, and the bridge 136 is formed to correspond to the partition wall 212. Therefore, when molding the soft film 135, the thickness t of the bridge 136 can be minimized, and for this purpose, 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 very thin state, the partition wall 212 may be damaged during the stretch forming process. In particular, according to the prior art, the mold has a bottom, but in this case, when the punch 22 molds the soft film 135, the gas present in the space between the soft film 135 and the molding portion 211 cannot be discharged. Therefore, recently, the bottom of the mold can be removed so that the gas present in the space between the soft film 135 and the molding portion 211 can be easily discharged, but the height of the partition wall 212 may be too high. Therefore, according to the embodiment of the present invention, as Figure 6 As shown, a reinforcing portion 2121, thicker than the partition wall 212, can be formed at the lower part of the partition wall 212. The reinforcing portion 2121 can be formed deeper than the depth D of the cup portion 133 to be formed in the battery casing 13, and the reinforcing portion 2121 can be formed at a position that will not damage the partition wall 212. The specific position of the reinforcing portion 2121 can be experimentally determined based on the thickness of the partition wall 212, the material of the partition wall 212, the pressure of the punch 22, and the depth D of the cup portion 133 to be formed.

[0132] Figure 7 This is an enlarged schematic diagram of the cup portion 333 and the bridge 336 based on existing technology.

[0133] As described above, in the prior art, aluminum alloys with alloy designations of the AA30XX series are frequently used when manufacturing the moisture barrier layer. Furthermore, the thickness of the moisture barrier layer is approximately 30 μm to approximately 50 μm, particularly approximately 40 μm, while the elongation auxiliary layer has a relatively thin thickness of approximately 15 μm. Therefore, due to the poor formability of the soft-pack film, even when manufacturing the battery casing and the secondary battery, the depth (D') of the cup portion 333 is not deep, thus limiting the ability to manufacture a soft-pack film with a sharp overall shape.

[0134] Specifically, there are limitations in reducing the radius of curvature of the edge 36 of the cup portion 333 according to the prior art.

[0135] The edge 36 of the cup portion 333 includes an edge 221 formed with the edge 221 of the punch 22 (see reference). Figure 6 The corresponding punch edge 361 and the edge 213 formed with respect to the mold 21 (reference) Figure 6 The corresponding mold edge 362 (reference) Figure 11 ).

[0136] The punch edge 361 connects each of the plurality of outer walls 338 surrounding the periphery of the cup portion 333 to the bottom 3332. However, if the edge 221 of the punch 22 is not rounded, the edge 221 of the punch 22 is sharp. As a result, when forming the soft film 135, stress is concentrated at the punch edge 361 of the cup portion 333, which can easily cause cracks. Furthermore, the die edge 362 connects each of the plurality of outer walls 338 to the side edge 134 or the degassing portion 137. If the pressing edge of the die 21 is not rounded, the pressing edge of the die 21 is sharp. Therefore, when forming the soft film, stress is concentrated at the die edge 362 of the cup portion 333, which can easily cause cracks. Here, rounding the die edge refers to forming a curved surface with curvature, and this surface may have only uniform curvature, but is not limited to this. For example, the surface may have non-uniform curvature. In this specification, the fact that the punch edge 161, the mold edge 162, the bridge 136, etc. are rounded with a specific curvature means that the punch edge 161, the mold edge 162, the bridge 136, etc. not only have a specific curvature as a whole, but also have a specific curvature only in at least a portion.

[0137] To solve the above problems, such as Figure 7 As shown, the edges 221 of the punch 22 and 213 of the die 21 are rounded to form rounded punch edges 361 and rounded die edges 362 of the cup portion 333. As a result, the stress concentrated at the punch edges 361 and die edges 362 of the cup portion 333 can be dispersed to a certain extent.

[0138] However, even if the punch edge 361 and the mold edge 362 of the cup portion 333 are formed to be rounded, the depth D' of the cup portion 333 can be limited to 2 to 5 times, specifically 2 to 3.25 times, the ratio of the radius of curvature of each of the edges 361 and 362.

[0139] Therefore, in order to form the depth D' of the cup portion 333 to a certain extent, the radius of curvature R2' of the punch edge 361 and the radius of curvature of the mold edge 362 must be large enough, and if the depth D' of the cup portion 333 is too deep compared with the radius of curvature of the punch edge 361 and the mold edge 362, cracks may occur in the punch edge 361 and the mold edge 362.

[0140] Therefore, in the prior art, when the depth D' of the cup portion 333 is formed sufficiently deep (e.g., more than 6.5 mm), there is a problem that it is difficult to form the radius of curvature R2' of the punch edge 361 and the radius of curvature of the mold edge 362 of the cup portion 333 within a range of specific values ​​(e.g., 2 mm).

[0141] Furthermore, when forming the two cup portions 133, the partition wall 212 must be present in the mold 21 to form the bridge 136. However, according to the prior art, the formability of the soft film is not excellent, thus limiting the ability to form the bridge 336 to a relatively thin thickness. That is, if the partition wall 212 is also formed to have a predetermined thickness or less, thereby forming the bridge 336 to a predetermined thickness or less, cracks may appear in the bridge 336 because the partition wall 212 is formed sharply.

[0142] To solve this problem, such as Figure 7 As shown, the bridge 336 is formed by rounding the partition wall 212. As a result, the stress concentrated on the bridge 336 can be dispersed to some extent. In particular, when the radius of curvature R1' of the bridge 336 is constant, the radius of curvature R1' corresponds to half of the thickness t' of the bridge 336. For example, when the radius of curvature R1' of the bridge 336 is formed to be approximately 1 mm, the thickness t' of the bridge 336 is formed to be approximately 2 mm.

[0143] However, even if the bridge 336 is rounded, if the radius of curvature R1' of the bridge 336 is small, cracks may occur in the bridge 336 when the depth D' of the cup portion 333 is formed to a certain extent. Therefore, in the prior art, there is a problem that when the cup portion 333 is formed to a certain depth D' (e.g., 6.5 mm) or more, it is difficult to form the thickness t' of the bridge 336 to be below a predetermined value (e.g., 2 mm).

[0144] Furthermore, since the gap CL' is also quite large, there are limitations to forming the outer wall 338 of the cup portion 333 into an approximately vertical state. The gap CL' refers to the vertical distance between the inner wall of the molding portion 211 of the mold 21 and the outer wall of the punch 22. In reality, there is a slight difference in size between the molding portion 211 of the mold 21 and the punch 22, which is as large as the gap CL'. If the gap CL' is too small, the distance between the inner wall of the molding portion 211 and the outer wall of the punch 22 will be too small. Then, the soft film 135 may not be able to be inserted into the molding portion 211, or the soft film 135 may be damaged due to large friction. On the other hand, if the gap CL' is too large, the tilt angle of the outer wall 338 of the cup portion 333 increases, and the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10 increases. Therefore, when molding the soft film 135, a gap CL of an appropriate size must be set.

[0145] The bridge 336 is formed to correspond to the partition wall 212 of the mold 21, and the punch edge 361 is formed to correspond to the edge 221 of the punch 22. Therefore, the gap CL', which is the vertical distance between the inner wall of the molding part 211 of the mold 21 and the outer wall of the punch 22, can represent the vertical distance between the bridge 336 and the punch edge 361 in the battery housing 33.

[0146] Specifically, such as Figure 7 As shown, the bridge perpendicular line V1' and the edge perpendicular line V2' are virtually represented. The bridge perpendicular line V1' is a virtual perpendicular line passing through the boundary point P1' between the bridge 336 and the outer wall 338 on the side of the bridge 336, and perpendicular to the bottom 3332. Similarly, the edge perpendicular line V2' is a virtual perpendicular line passing through the boundary point P2' between the edge 361 of the punch on the side of the bridge 336 and the outer wall 338 on the side of the bridge 336, and perpendicular to the bottom 3332. The bridge perpendicular line V1' corresponds to the inner wall of the molding portion 211 of the mold 21, specifically the inner wall of the partition 212, while the edge perpendicular line V2' corresponds to the outer wall of the punch 22. Therefore, the vertical distance between the bridge perpendicular line V1' and the edge perpendicular line V2' corresponds to the gap CL' generated in the battery housing 33.

[0147] However, in the prior art, when the gap CL' is reduced to 0.5 mm or less, and when the depth D' of the cup portion 333 is formed to a certain extent, cracks may easily appear in the soft membrane 135.

[0148] As described above, in the prior art, there are limitations in making the gap CL' smaller and the depth D' of the cup portion 333 deeper. For example, when the cup portion 333 is formed to a predetermined depth D' (e.g., 6.5 mm) or greater, the outer wall 338 of the cup portion 333 has an inclination angle greater than 95° from the bottom 3332. That is, there are limitations in forming the outer wall 338 of the cup portion 333 at an inclination angle of 95° or less to a near-vertical state.

[0149] Furthermore, due to limitations in increasing the radius of curvature R2' of the edge of the cup portion 333, there is also a problem of reduced volume of the electrode assembly 10 housed in the cup portion 333. Specifically, as Figure 7 As shown, in the prior art, because the radius of curvature R2' of the punch edge 361 of the cup portion 333 is large, when the electrode assembly 10 is positioned too close to the outer wall 338 of the cup portion 333, there is a problem that the electrode 101 of the electrode assembly 10 is damaged by the punch edge 361 of the cup portion 333. That is, the metal-containing end of the electrode 101 is disposed on the punch edge 361 of the cup portion 333, and this end of the electrode 101 deforms to correspond to the punch edge 361 of the cup portion 333, causing damage.

[0150] To solve this problem, in the prior art, when the electrode assembly 10 is housed in the cup portion 333, the electrode assembly 10 is housed at a certain distance from the outer wall 338 of the cup portion 333. First, the vertical distance g' from the edge perpendicular line V2' is 0.75 mm, specifically 0.5 mm, and a reference perpendicular line V3' perpendicular to the bottom 3332 is virtually shown. Then, as... Figure 7As shown, the electrode assembly 10 is housed such that one end of the electrode 101 is positioned outside the reference vertical line V3'. Therefore, since the electrode 101 is spaced to a certain extent from the outer wall 338 of the cup portion 333, damage to the electrode 101 can be prevented. However, in this case, because the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10 increases, the volume ratio of the electrode assembly 10 to the cup portion 333 decreases, resulting in a decrease in the energy density of the secondary battery 3 relative to its volume. Furthermore, because the volume of unnecessary space within the cup portion 333 increases, there is also a problem that the electrode assembly 10 may move within the cup portion 333 before reaching the sealing side surface.

[0151] Furthermore, in the electrode assembly 10, the electrode 101 has high rigidity and is not easily deformed by external forces, while the partition 102 has high flexibility and is easily deformed by external forces. However, when adjacent electrodes 101 come into direct contact with each other, a short circuit will occur. Therefore, to prevent short circuits, the partition 102 is formed to be larger than the electrode 101. Thus, when forming the electrode assembly 10, the peripheral portion 1021 of the partition 102 that protrudes further outward than the electrode 101 is formed together. However, in the prior art, since the electrode assembly 10 is housed at a certain distance from the outer wall 338 of the cup portion 333, the peripheral portion 1021 of the partition 102 is randomly wrinkled or folded to expose the electrode 101 to the outside, thereby increasing the possibility of a short circuit.

[0152] As described above, in the prior art, due to the poor formability of the soft-film, there are limitations in increasing the thickness t' of the bridge 336, the depth D' of the cup 333, the radius of curvature R2' of the edge 361 of the cup 333, and the gap CL'. Furthermore, because the volume ratio of the electrode assembly 10 to the cup 333 is small, the unnecessary volume in the secondary battery 3 is also large, thus reducing the energy density relative to volume. In addition, because the outer wall 338 of the cup 333 is not formed in an approximately vertical state, and the radius of curvature R2 of the edge 361 of the cup 333 is also large, there are limitations in manufacturing a sharp shape overall. As a result, the secondary battery 3 has an unattractive appearance and reduced marketability.

[0153] Figure 8 This is an enlarged schematic diagram of the cup portion 133 and the bridge 136 according to an embodiment of the present invention. Figure 9 This is an enlarged schematic diagram of the cup portion 133 and the degassing portion 137 according to an embodiment of the present invention.

[0154] According to embodiments of the present invention, as the formability of the pouch film 135 is improved, the thickness t of the bridge 136 is made thinner, the radius of curvature R2 of the edge 16 of the cup portion 133 and the gap CL' can be made smaller, and the volume of the electrode assembly 10 can be increased. Therefore, since the unnecessary volume in the secondary battery 1 is also reduced, the energy density relative to volume can be increased. In addition, since each of the pouch battery casing 13 and the pouch secondary battery 1 is integrally manufactured with a sharp shape, the appearance of the secondary battery 1 can be excellent, and its marketability can be improved.

[0155] Therefore, in the pouch-type battery casing 13 according to an embodiment of the present invention, a cup portion 133 is formed therein, wherein an electrode assembly 10 is formed by stacking electrodes 101 and separators 102. However, the cup portion 133 includes a plurality of punch edges 161, which connect each of a plurality of outer walls 138 surrounding the periphery to a bottom 1332, and at least one punch edge 161 is rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. If the radius of curvature R2 of the punch edge 161 is smaller than 1 / 20 of the depth D of the cup portion 133, stress may be excessively concentrated at the punch edge 161, leading to cracks. On the other hand, if the radius of curvature R2 of the punch edge 161 is larger than 1 / 6 of the depth D of the cup portion 133, the cup portion 133 may not be formed sharply, and therefore the energy density may be reduced.

[0156] Specifically, at least one of the punch edges 161 may be rounded with a radius of curvature of less than 1 mm, specifically with a radius of curvature of less than 0.7 mm.

[0157] Furthermore, the pouch-type secondary battery may include: a first housing 131 and a second housing 132, in which cup portions 133 are formed respectively; and a bridge 136 formed between the two cup portions 133, wherein the thickness of the bridge 136 may be 1 / 200 to 1 / 30 of the width of the electrode assembly 10. If the thickness t of the bridge 136 is less than 1 / 200 of the width of the electrode assembly 10, stress may be excessively concentrated at the bridge 136, and thus cracks may occur. When the width of the electrode assembly 10 is greater than 1 / 30 of the width of the electrode assembly 10, the bridge 136 may not be formed sharply, and thus the energy density may decrease.

[0158] Specifically, the thickness of bridge 136 can be less than 2mm, specifically less than 1.4mm.

[0159] Furthermore, among the plurality of punch edges 161, the bridge 136-side punch edge 1611 that connects the bridge 136-side outer wall 1381 facing the bridge 136 to the bottom 1332 can be rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1611 can be rounded with a radius of curvature of 1 mm or less, specifically with a radius of curvature of 0.7 mm or less.

[0160] In addition, the bridge perpendicular line V1 passes through the boundary point P1 between the bridge 136 and the outer wall 1381 of the bridge 136 and is perpendicular to the bottom 1332. The edge perpendicular line V2 passes through the boundary point P2 between the edge 1611 of the punch on the side of the bridge 136 and the outer wall 1381 of the bridge 136 and is perpendicular to the bottom 1332. The vertical distance between the bridge perpendicular line V1 and the edge perpendicular line V2 can be less than 0.5mm, specifically less than 0.35mm.

[0161] The cup portion 133 is formed by molding a flexible soft membrane 135 using a punch 22 or the like. The cup portion 133 is surrounded by a plurality of outer walls 138 and a bottom 1332, and the space formed by the outer walls 138 and the bottom 1332 serves as a receiving space 1331 to receive the electrode assembly 10.

[0162] The outer wall 138 of the cup portion 133 surrounds the periphery of the cup portion 133 to form the shape of the cup portion 133. Multiple outer walls 138 are formed around the cup portion 133, including one side of the bridge 136, one side of the degassing portion 137 (described later), and one side of the electrode lead 12. The outer wall 138 has an upper end facing the opening of the cup portion 133 and a lower end facing the bottom 1332.

[0163] As described above, the edge 16 of the cup portion 133 includes a punch edge 161 formed to correspond to the edge 221 of the punch 22 and an edge 213 formed to correspond to the edge 221 of the mold 131 (see reference). Figure 6 The corresponding mold edge 362. A side edge 134 and a degassing portion 137 are formed outward from the upper end of the outer wall 138, and the mold edge 162 connects the upper end of the outer wall 138 to the side edge 134 or the degassing portion 137. Furthermore, the punch edge 161 connects the lower end of the outer wall 138 to the bottom 1332.

[0164] Since the outer walls 138 of the cup portion 133 are formed in multiple ways, the edges 16 of the cup portion 133 are also formed in the same number as the outer walls 138. That is, if the cup portion 133 is formed as a quadrilateral, since there are also four outer walls 138 of the cup portion 133, four punch edges 161 and four mold edges 162 are also formed. According to an embodiment of the invention, as the formability of the soft film 135 is improved, at least one punch edge 161 of the cup portion 133 is rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one of the punch edges 161 may be rounded with a radius of curvature of less than 1 mm, specifically with a radius of curvature of less than 0.7 mm.

[0165] Specifically, according to an embodiment of the invention, two cup portions 133 are formed on a soft membrane 135, and a bridge 136 is also formed between the two cup portions 133. Furthermore, as... Figure 8 As shown, among the plurality of punch edges 161, the bridge 136-side punch edge 1611 that connects the bridge 136-side outer wall 1381 facing the bridge 136 to the bottom 1332 can be formed with a rounded radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the bridge 136-side punch edge 1611 can be formed with a rounded radius of curvature of 1 mm or less, specifically with a rounded radius of curvature of 0.7 mm or less.

[0166] In addition, such as Figure 9 As shown, among the multiple punch edges 161, the die edge 162-side punch edge that connects to the bottom 1332 with the die edge 162-side outer wall 1382 facing the die edge 162 formed on the degassing section 137 or electrode lead 12 can also be rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. If the radius of curvature of the die edge 162 is smaller than 1 / 20 of the depth D of the cup portion 133, stress may be excessively concentrated on the die edge 162, leading to cracks. On the other hand, if the radius of curvature of the die edge 162 is larger than 1 / 6 of the depth D of the cup portion 133, the upper end of the cup portion 133 cannot be formed sharply, and therefore the energy density may be reduced.

[0167] Specifically, the punch edge 1612 on the side of the mold edge 162 can be rounded with a radius of curvature of less than 1 mm, specifically with a radius of curvature of less than 0.7 mm. In this case, at the boundary points P2 and P4 between the punch edge 161 and the outer wall 138, the slope is preferably continuous.

[0168] Therefore, the edge 221 of the punch 22 can also be rounded with a predetermined radius of curvature. Here, the radius of curvature of the edge 221 of the punch 22 can be a value obtained by subtracting the thickness of the soft film 135 itself from the radius of curvature R2 of the punch edge 161. For example, if the thickness of the soft film 135 is 0.2 mm, then when the radius of curvature of the edge 221 of the punch 22 is 0.5 mm or less, the radius of curvature R2 of the punch edge 161 is 0.7 mm or less.

[0169] According to an embodiment of the present invention, as the formability of the soft film 135 is improved, even if the depth D of the cup portion 133 is formed to a certain extent, when the soft film 135 is stretched and formed by the punch 22, cracks can be prevented from appearing in the punch edge 161 of the cup portion 133. For example, even if the cup portion 133 is molded to a depth of 7 mm or more based on the case where one cup portion 133 is molded, to a depth of 6.5 mm or more based on the case where two cup portions 133 are molded, or even to a depth of 10 mm or more based on the case where the cup portion 133 is molded, cracks can still be prevented from appearing in the punch edge 161 of the cup portion 133.

[0170] Here, as described above, based on the residual rate of the aluminum alloy in the moisture barrier layer 1352, the depth (D) of the cup portion 133 at a location where cracks may occur can be determined to be good if the residual rate is 60% or more, and defective if the residual rate is less than 60%. The residual rate refers to the ratio of the amount of aluminum alloy remaining in the moisture barrier layer 1352 at a specific point on the flexible film 135 after forming to the amount remaining before forming. In fact, when the residual rate is less than 60%, cracks occur frequently at specific points when the cup portion 133 is stretched and formed on the flexible film 135, but when the residual rate is 60% or more, cracks do not occur.

[0171] In the prior art, when the depth D' of the cup portion 333 is formed to be greater than 5 times, specifically 3.25 times, the radius of curvature R2' of the punch edge 361 or the radius of curvature of the mold edge 362, the residual rate is relatively low, and therefore the frequency of crack occurrence is high. Hereinafter, "prone to cracking" refers to a low residual rate and a high frequency of crack occurrence.

[0172] The outer wall 138 has an upper end facing the opening of the cup portion 133, and the side 134 and the degassing portion 137 extend to the outer side of the cup portion 133. Here, as... Figure 9As shown, the cup portion 133 may further include a plurality of mold edges 162, which connect the upper end of the outer wall 138 to the side 134 or the degassing portion 137. Furthermore, at least one mold edge 162 may be rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one mold edge 162 may be rounded with a radius of curvature of 1 mm or less, specifically 0.7 mm or less. For this purpose, the edge 213 of the mold 21 may also be rounded with a predetermined radius of curvature. Here, the radius of curvature of the edge 213 of the mold 21 may be a value obtained by subtracting the thickness of the soft film 135 itself from the radius of curvature of the mold edge 162. For example, if the thickness of the soft film 135 is 0.2 mm, then when the radius of curvature of the edge 213 of the mold 21 is less than 0.5 mm, the radius of curvature of the mold edge 162 is less than 0.7 mm.

[0173] Specifically, as described above, the two cup portions 133 can be formed on a soft-pack film 135, and the bridge 136 is also formed between the two cup portions 133. That is, the soft-pack battery casing 13 according to an embodiment of the present invention includes: a first casing 131 and a second casing 132, in which cup portions 133 are formed respectively, the cup portions 133 accommodating electrode assemblies 10, the electrode assemblies 10 being formed by stacking electrodes 101 and separators 102; and a bridge 136 formed between the two cup portions 133. Since the bridge 136 is also formed to correspond to the partition wall 212 of the mold 21, the bridge 136 can be one of a plurality of mold edges 162.

[0174] Therefore, according to an embodiment of the present invention, as the formability of the soft film 135 improves, the thickness t of the bridge 136 can be the width EW of the electrode assembly 10 (refer to...). Figure 10 The thickness t of bridge 136 can be 1 / 200 to 1 / 30 of that of bridge 136. Specifically, the thickness t of bridge 136 can be formed to be less than 2 mm, specifically less than 1.4 mm.

[0175] Here, as Figure 8 As shown, the thickness t of bridge 136 is preferably the distance between two boundary points P1 of bridge 136 and the outer side wall 1381 of bridge 136. Specifically, the thickness t of bridge 136 is preferably the distance between two perpendicular lines V1 passing through the boundary point P1 of bridge 136 and the outer side wall 1381 of bridge 136, and the two perpendicular lines V1 are perpendicular to the bottom 1332. Therefore, when bridge 136 has a constant radius of curvature, the radius of curvature of bridge 136 can correspond to half of the thickness t. That is, the radius of curvature of bridge 136 can be less than 1 mm, specifically less than 0.7 mm.

[0176] Therefore, the top surface of the partition wall 212 of the molding section 211 can also be rounded with a predetermined radius of curvature. In this case, at the boundary point P1 between the bridge 136 and the outer side wall 1381 of the bridge 136, the slope is preferably continuous. Here, the radius of curvature of the top surface of the partition wall 212 of the molding section 211 can be a value obtained by subtracting the thickness of the soft film 135 itself from the radius of curvature of the bridge 136. For example, if the thickness of the soft film 135 is 0.2 mm, then when the radius of curvature of the top surface of the partition wall 212 is 0.5 mm or less, the radius of curvature of the bridge 136 is 0.7 mm or less.

[0177] According to an embodiment of the present invention, as the formability of the soft film 135 is improved, the depth D of the cup portion 133 is molded to a certain extent. Therefore, even if the radius of curvature of the edge 213 of the mold 21 is reduced and the thickness of the partition wall 212 is formed to be thinner, cracks in the mold edge 162 and the bridge 136 can be prevented. The bridge 136 can have a fan-shaped cross-section, and as the outer wall 138 of the cup portion 133 is formed to be approximately vertical, the cross-section can have a shape closer to a semi-circular shape.

[0178] Here, even if the cup portion 133 is molded to a depth D of 3mm or more, specifically 6.5mm or more, or more specifically 10mm or more, based on the case of molding two cup portions 133, cracks can be prevented from appearing in the bridge 136.

[0179] Furthermore, with the improved formability of the soft membrane 135, the gap CL' can be reduced to below 0.5 mm, allowing all the outer walls 138 to be formed in an approximately vertical state. For example, as... Figure 8 As shown, the outer wall 1381 on the side of the bridge 136 among the multiple outer walls 138 can be formed in an approximately vertical state. That is, the bridge perpendicular line V1 passes through the boundary point P1 between the bridge 136 and the outer wall 1381 on the side of the bridge 136 and is perpendicular to the bottom 1332, and the edge perpendicular line V2 passes through the boundary point P2 between the edge 1611 of the punch on the side of the bridge 136 and the outer wall 1381 on the side of the bridge 136 and is perpendicular to the bottom 1332. The gap CL', which is the vertical distance between the bridge perpendicular line V1 and the edge perpendicular line V2, can be less than 0.5 mm, specifically less than 0.35 mm.

[0180] In addition, such as Figure 9As shown, the outer wall 1382 on the mold edge 162 side among the multiple outer walls 138 can also be formed in an approximately vertical state. That is, the mold edge vertical line V4 passes through the boundary point P3 of the mold edge 162 and the outer wall 1382 on the mold edge 162 side and is perpendicular to the bottom 1332, and the edge vertical line V2 passes through the boundary point P4 of the punch edge 1612 on the mold edge 162 side and the outer wall 1382 on the mold edge 162 side and is perpendicular to the bottom 1332. The gap CL', which is the vertical distance between the mold edge vertical line V4 and the edge vertical line V2, can be less than 0.5 mm, specifically less than 0.35 mm.

[0181] Therefore, even when the depth D of the cup portion 133 is 3 mm or more, specifically 6.5 mm or more, or more specifically 10 mm or more, based on the case of molding two cup portions 133, the inclination angle between the outer wall 138 of the cup portion 133 and the bottom 1332 can be 90° to 95°, and can further be formed into an approximately vertical state with an inclination angle between 90° and 93°, thus preventing cracks from appearing in the battery casing 13. Furthermore, since the space between the outer wall 138 of the cup portion 133 and the electrode assembly 10 can also be reduced, the energy density of the secondary battery 1 relative to its volume can also be increased.

[0182] Since the radius of curvature R2 of the punch edge 161 of the cup portion 133 can be further reduced, the electrode 101 of the electrode assembly 10 can be prevented from being damaged even when the electrode assembly 10 is set very close to the outer wall 138 of the cup portion 133.

[0183] Therefore, a method for manufacturing a pouch-type secondary battery 1 according to an embodiment of the present invention includes the following steps: forming an electrode assembly 10 by stacking electrodes 101 and separators 102; molding a pouch film 135 to form a cup portion 133 to manufacture a pouch-type battery casing 13; accommodating the electrode assembly 10 in the accommodating space 1331 of the cup portion 133; and sealing the side 134 extending to the outside of the cup portion 133 to manufacture the pouch-type secondary battery 1.

[0184] Specifically, in the step of accommodating the electrode assembly 10, the difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 can be 2.5 mm or less, specifically 1.7 mm or less. Here, the width EW of the electrode assembly 10 can refer to the width of the electrode 101. That is, the peripheral portion 1021 that protrudes from the partition 102 rather than from the electrode 101 can be excluded from the calculation of the width EW.

[0185] Furthermore, the electrode assembly 10 can be accommodated such that at least one end of the electrode 101 is positioned at a vertical distance g of 0.75 mm from the edge vertical line V2, specifically a vertical distance g of less than 0.5 mm, the edge vertical line V2 passing through the boundary point P2 between the punch edge 161 and the outer wall 138 and perpendicular to the bottom 1332.

[0186] Specifically, such as Figure 8 and Figure 9 As shown, a perpendicular line V2, passing through the boundary point P2 of the punch edge 161 and the outer wall 138 and perpendicular to the bottom 1332, is virtually illustrated. Furthermore, an electrode assembly 10 is accommodated such that at least one end of the electrode assembly 10 is at a vertical distance g from the perpendicular line V2 of 0.75 mm or less, specifically 0.5 mm or less. More specifically, the vertical distance g from the perpendicular line V2 is 0.75 mm, specifically 0.5 mm, and a reference perpendicular line V3, perpendicular to the bottom 1332, is virtually illustrated. Here, since the radius of curvature R2 of the punch edge 161 can be specifically 0.7 mm or less, the reference perpendicular line V3 can pass through the center of curvature C of the punch edge 161. The electrode assembly 10 is accommodated such that one end of the electrode 101 is positioned between the perpendicular line V2 and the reference perpendicular line V3. This can be confirmed by disassembling the secondary battery 1 itself, but is not limited to this, and can be confirmed by various methods without disassembling the secondary battery 1, such as computed tomography (CT), magnetic resonance imaging (MRI), X-ray, etc. As a result, the ratio of the volume of the electrode assembly 10 to the volume of the cup portion 133 can be further increased while preventing damage to the electrode 101, thus increasing the energy efficiency relative to volume. In addition, since unnecessary volume inside the cup portion 133 is reduced, movement of the electrode assembly 10 within the cup portion 133 can be prevented.

[0187] Furthermore, because the electrode assembly 10 is housed very close to the outer wall 138 of the cup portion 133, the partition 102 will not be disorderly wrinkled or folded. Figure 8 As shown, the peripheral portion 1021 of the partition 102 protruding outward from the electrode 101 is folded in the opposite direction to the bottom 1332 relative to one end of the electrode 101.

[0188] The electrode assembly 10 is formed by stacking electrodes 101 and separators 102, and multiple electrodes 101 and multiple separators 102 can be formed. The battery housing 13 includes a first housing 131 and a second housing 132. If the bridge 136 of the battery housing 13 is folded to accommodate the upper part of the electrode assembly 10 in the cup portion 133, the separators 102 accommodated in the cup portion 133 of the first housing 131 are configured such that their peripheral portions 1021 are folded to face the second housing 132, and the separators 102 accommodated in the cup portion 133 of the second housing 132 are configured such that their peripheral portions 1021 are folded to face the first housing 131. Thus, the peripheral portions 1021 of the separators 102 are aligned and folded in an orderly manner. Furthermore, since the separators 102 cover the electrodes 101 so as not to expose them to the outside, short circuits can be prevented.

[0189] More specifically, in the state before the electrode assembly 10 is housed in the cup portion 133, the width of the partition 102 can be wider than the width CW of the cup portion 133. Therefore, when the electrode assembly 10 is housed in the cup portion 133, the peripheral portion 1021 of the partition 102 can be folded in a predetermined direction and come into contact with the inner periphery of the cup portion 133.

[0190] The difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 can be very small, for example, less than 2.5 mm, specifically less than 1.7 mm. Therefore, it may be necessary to easily fold the peripheral portion 1021 of the partition 102 while accommodating the electrode assembly 10 in the cup portion 133.

[0191] Therefore, the step of accommodating the electrode assembly 10 in the receiving space 1331 of the cup portion 133 may include pressing the electrode assembly 10 into the cup portion 133. Thus, compared to conventional methods of placing the electrode assembly 10 on the cup portion, the partition 102 can be folded in a specific direction while maintaining a small difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10, thereby allowing the electrode assembly 10 to be easily and reliably accommodated in the receiving space of the cup portion 133.

[0192] Furthermore, the step of accommodating the electrode assembly 10 in the receiving space 1331 of the cup portion 133 may further include a process of folding each corner (vertices) of the plurality of partitions 102 in the electrode assembly 10 before pressing the electrode assembly 10 into the interior of the cup portion 133. In the above process, each corner (vertices) of the plurality of partitions 102 can be folded using a separate sealing tool to gather them at the center in the stacking direction of the electrode assembly 10.

[0193] That is, the electrode assembly 10 can be inserted into the cup portion 133 with the four corners of the separator 102 pre-aligned. Therefore, the electrode assembly 10 can be smoothly inserted into the receiving space 1331 of the cup portion 133. As described above, according to an embodiment of the present invention, with the improved formability of the soft-pack film 135, the thickness t of the bridge 136 can be made thinner, the radius of curvature R2 of the edge 16 of the cup portion 133 and the gap CL' can be made smaller, and the volume of the electrode assembly 10 can be increased. Therefore, since the unnecessary volume in the secondary battery 1 is also reduced, the energy density relative to volume can be increased. Furthermore, since each of the soft-pack battery casing 13 and the soft-pack secondary battery 1 is integrally manufactured with a sharp shape, the appearance of the secondary battery 1 can also be aesthetically pleasing, and its marketability can be improved.

[0194] Figure 10 This is a schematic top view showing the state in which the electrode assembly 10 according to an embodiment of the present invention is housed in the cup portion 133.

[0195] According to an embodiment of the present invention, as described above, because the radius of curvature R2 of the punch edge 161 of the cup portion 133 is further reduced, the electrode assembly 10 is accommodated such that one end of the electrode 101 is positioned between the edge vertical line V2 and the reference vertical line V3. Therefore, even when the electrode assembly 10 is positioned very close to the outer wall 138 of the cup portion 133, damage to the electrode 10 of the electrode assembly 10 can be prevented.

[0196] The edge perpendicular line V2 and the reference perpendicular line V3 can also be shown on the punch edge 1611 on the bridge 136 side, or on the punch edge 1612 on the mold edge 162 side. The vertical distance g between the edge perpendicular line V2 and the reference perpendicular line V3 can be 0.75 mm, specifically 0.5 mm.

[0197] Furthermore, if two cup portions 133 are formed in the battery casing 13, due to the presence of a bridge 136, the bridge perpendicular line V1 can be shown on one side of the cup portion 133, and the mold edge perpendicular line V4 can be shown on the other side of the cup portion 133. The vertical distance CL between the bridge perpendicular line V1 and the edge perpendicular line V2 can be 0.5 mm or less, specifically 0.35 mm or less, and the vertical distance CL between the mold edge perpendicular line V4 and the edge perpendicular line V2 can also be 0.5 mm or less, specifically 0.35 mm or less.

[0198] However, if only one cup portion 133 is formed in the battery housing 13, there is no bridge. However, since the mold edge 162 is formed on each of the two sides of the cup portion 133, the mold edge vertical line V4 can be shown on each of the two sides of the cup portion 133.

[0199] If two cup portions 133 are formed in the battery casing 13, the width CW of the cup portion 133 can represent the vertical distance from the bridge perpendicular line V1 to the mold edge perpendicular line V4. However, if only one cup portion 133 is formed, the width CW of the cup portion 133 can represent the vertical distance between the two mold edge perpendicular lines V4.

[0200] Both the bridge perpendicular line V1 and the mold edge perpendicular line V4 pass through the top of the outer wall 138 of the cup portion 133. Therefore, according to an embodiment of the present invention, the width CW of the cup portion 133 can be the vertical distance between the upper ends of the outer walls 138 on both sides of the cup portion 133. The difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 can be less than 2.5 mm, specifically less than 1.7 mm. Furthermore, as described above, the width EW of the electrode assembly 10 can be 60 mm or more.

[0201] The width CW of the cup portion 133 can be derived by measuring the vertical distance between the upper ends of the outer walls 138 on both sides of the cup portion 133 in the battery housing 13. Furthermore, in the secondary battery 1, the position between the upper ends of the outer walls 138 on both sides can be determined from the outside of the cup portion 133 using a laser displacement sensor or the like, and the distance between these two positions can be derived by calculation. Here, when a laser displacement sensor moves from the side 134 towards the mold edge 162 and the outer wall 138 while irradiating the cup portion 133 with a laser from the outside, to detect a point of sudden displacement change, the corresponding point can be identified as the upper end of the outer wall 138. The above description is an example of a method for measuring the width CW of the cup portion, but the method is limited to the above-described measurement method and is not included in the scope of this invention. The width CW of the cup portion can be any width CW of the cup portion in the sense of this invention, provided it falls within the scope of the claims and the spirit of this invention.

[0202] Figure 11 This is a schematic diagram of corner 364 based on existing technology. Figure 12 This is a schematic diagram of corner 164 according to an embodiment of the present invention.

[0203] like Figure 12 As shown, the edge 16 of the cup portion 133 may further include a thickness edge 163, a punch edge 161, and a mold edge 162. The thickness edge 163 connects two adjacent outer walls 138 of the cup portion 133. This thickness edge 163 is formed along the thickness direction of the cup portion 133 and is formed simultaneously with the elongation of the soft film 135 between the corner of the mold 21 and the corner of the punch 22. Furthermore, at least one of the thickness edges 163 may be rounded.

[0204] The radius of curvature of the thickness edge 163 can be the same as, but is not limited to, the radius of curvature R2 of the two adjacent punch edges 161, namely the first punch edge 1613 and the second punch edge 1614. For example, the thickness edges can be formed differently. For example, as described above, at least one of the punch edges 161 can be rounded with a radius of curvature of less than 1 mm, specifically less than 0.7 mm, and at least one of the thickness edges 163 can be rounded with a radius of curvature of 0.5 mm to 5 mm, specifically 0.5 mm to 2 mm. According to the prior art, when the thickness edge 363 is formed to be rounded with a radius of curvature of less than 5 mm, specifically less than 2 mm, there is a problem that stress is also concentrated on the thickness edge 363 of the cup portion 333, causing cracks. However, according to an embodiment of the present invention, even when the depth D of the cup portion 133 is formed to a certain extent, cracks can be prevented from appearing in the thickness edge 163 of the cup portion 133. Here, one of the first punch edge 1613 and the second punch edge 1614 can be the punch edge 1611 on the bridge 136 side, and the other can be the punch edge on the electrode lead 12 side (not shown). Alternatively, one of the two punch edges can be the punch edge 1612 on the mold edge 162 side, and the other can be the punch edge on the electrode lead 12 side (not shown).

[0205] Thickness edge 163 as Figure 12 The two adjacent punch edges 161, namely the first punch edge 1613 and the second punch edge 1614, are connected to form a corner 164. In the prior art, such as Figure 11 As shown, all the multiple edges 221 of the punch 22 are rounded with the same radius of curvature, so the corners (not shown) of the punch 22 are naturally rounded with the same radius of curvature as well. Therefore, when the soft film 135 is stretched by molding the soft film 135 with the punch 22, the corners 364 are naturally rounded with the same radius of curvature as the punch edges 361.

[0206] However, when the flexible film 135 is stretched, there is a problem of stress concentration at the corner 364. In particular, the corner 364 is formed by the intersection of three edges 36, and therefore the corner 364 elongates more than the punch edge 361 or the thickness edge 363. Consequently, stress may be more concentrated at the corner 364 compared to the punch edge 361 or the thickness edge 363. Therefore, excessive stretching of the flexible film 135 causes whitening and eventually makes it prone to cracking, in which specific portions turn white just before cracks appear.

[0207] Therefore, according to embodiments of the present invention, such as Figure 12As shown, corner 164 is also rounded, and the radius of curvature of corner 164 is greater than or equal to the radius of curvature of at least one of the punch edge 161 and the thickness edge 163.

[0208] Specifically, according to an embodiment of the present invention, the radius of curvature can vary inside the corner 164. That is, the radius of curvature of the central portion 1641 of the corner 164 and the radius of curvature of the peripheral portion 1642 of the corner 164 can be different from each other. In particular, the radius of curvature of the central portion 1641 of the corner 164 can be larger than the radius of curvature of the peripheral portion 1642 of the corner 164. For example, since it is adjacent to the first punch edge 1613, the second punch edge 1614 and the thickness edge 163, the radius of curvature of the peripheral portion 1642 of the corner 164 can be the same as the radius of curvature of at least one of the punch edge 161 and the thickness edge 163. On the other hand, since it is spaced apart from the first punch edge 1613, the second punch edge 1614 and the thickness edge 163, the radius of curvature of the central portion 1641 of the corner 164 can be larger than the radius of curvature of at least one of the punch edge 161 and the thickness edge 163. In other words, the radius of curvature of corner 164 can be different from the radius of curvature of at least one of punch edge 161 and thickness edge 163.

[0209] Therefore, the radius of curvature of corner 164 can gradually increase from the periphery 1642 of corner 164 to the center 1641 of corner 164. Furthermore, since the radius of curvature on the inner side of corner 164 is not constant but varies, the center 1641 of corner 164 can have an aspherical shape rather than a precise spherical shape.

[0210] Unlike the punch edge 161, the corner 164 must not only have its radius of curvature clearly defined, but also its range within the cup portion 133 must be clearly defined. If the range within which the corner 164 is formed in the cup portion 133 is too narrow, the soft film 135 will still be excessively stretched, leading to whitening or cracking. On the other hand, if the range within which the corner 164 is formed in the cup portion 133 is too wide, the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10 will decrease, and thus the energy density of the secondary battery 1 relative to its volume will increase. Therefore, according to an embodiment of the invention, as Figure 12 As shown, the corner 164 can be formed such that it is within a range of 2 mm to 3.5 mm from the thickness edge 163 in the longitudinal direction 1c of the cup portion 133, within a range of 2 mm to 3.5 mm from the thickness edge 163 in the width direction Wc of the cup portion 133, and within a range of 2 mm to 3.5 mm from the punch edge 161 in the thickness direction dc of the cup portion 133. Furthermore, the range in which the corner 164 is formed can gradually widen as the depth D of the cup portion 133 increases.

[0211] Because of the corner 164 formed by the cup portion 133 as described above, the stress concentrated at the corner 164 can be dispersed, thereby preventing whitening and cracking.

[0212] Figure 13 This is a schematic diagram showing the folded state of the battery casing 13 according to an embodiment of the present invention. Figure 14 This is a schematic diagram showing the folded state of the battery casing 13 according to an embodiment of the present invention.

[0213] When the two cup portions 133 are formed in the soft film 135, the cup portions 133 are respectively formed in the first housing 131 and the second housing 132 of the battery housing 13. Figure 13 As shown, after the electrode assembly 10 is housed in the receiving space 1331 provided in the cup portion 133 of the first housing 131, a bridge 136 formed between the two cup portions 133 is folded in the battery housing 13 so that the two cup portions 133 face each other. As the bridge 136 is folded, a folded portion 139 is formed on one side of the secondary battery 1. Then, as... Figure 14 As shown, an electrolyte is injected, and then the side 134 extending to the outside of the cup portion 133 of the first housing 131 and the second housing 132 can be sealed to manufacture a pouch-type secondary battery.

[0214] The pouch-type secondary battery 1 manufactured as described above according to an embodiment of the present invention may include: an electrode assembly 10, in which electrodes 101 and separators 102 are stacked; and a pouch-type battery housing 13 having a cup portion 133 therein for receiving the electrode assembly 10, wherein the cup portion 133 includes a plurality of punch edges 161, the plurality of punch edges 161 respectively connecting a plurality of outer walls 138 to a bottom 1332. At least one of the punch edges 161 may be rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one of the punch edges 161 may be rounded with a radius of curvature of less than 1 mm, specifically with a radius of curvature of less than 0.7 mm.

[0215] The difference between the width CW of the cup portion 133 and the width EW of the electrode assembly 10 can be less than 2.5 mm, specifically less than 1.7 mm. Furthermore, the electrode assembly 10 can be accommodated such that at least one end of the electrode 101 is positioned at a vertical distance g from the edge perpendicular line V2 of 0.75 mm, specifically less than 0.5 mm, which passes through the boundary point P2 between the punch edge 161 and the outer wall 138 and is perpendicular to the bottom 1332. Additionally, the battery housing 13 may include: a first housing 131 and a second housing 132, at least one of which has the cup portion 133 formed on it; and a folding portion 139 that integrally connects the first housing 131 and the second housing 132.

[0216] When the secondary battery 1 is manufactured by folding the battery casing 13, the bridge 136 becomes the folding portion 139, thus the folding portion 139 integrally connects the first casing 131 and the second casing 132 in the secondary battery 1. Furthermore, the punch edge 1611 on the side of the bridge 136 becomes the punch edge 1611 on the side of the folding portion 139, and the outer wall 1381 on the side of the bridge 136 becomes the outer wall 1381 on the side of the folding portion 139.

[0217] Furthermore, among the plurality of punch edges 161, the punch edge 1611 on the folding portion 139 side, which connects to the outer wall 1381 of the folding portion 139 facing the folding portion 139 and the bottom 1332, can be rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1611 on the folding portion 139 side can be rounded with a radius of curvature of 1 mm or less, specifically with a radius of curvature of 0.7 mm or less. In addition, the electrode assembly 10 can be accommodated such that at least one end of the electrode 101 is disposed between the edge vertical line V2 and the reference vertical line V3, the edge vertical line V2 passing through the boundary point P2 between the punch edge 161 and the outer wall 138 and perpendicular to the bottom 1332, the reference vertical line V3 being at a vertical distance g from the edge vertical line V2 of 0.75 mm, specifically 0.5 mm or less, and the reference vertical line V3 being perpendicular to the bottom 1332. As described above, the reference vertical line V3 can pass through the curvature center C of the punch edge 161.

[0218] Figure 15 This is an enlarged view of the groove 1391 formed in the battery housing 13 according to an embodiment of the present invention.

[0219] According to an embodiment of the present invention, when the battery casing 13 is folded as described above to manufacture the secondary battery 1, the bridge 136 can be in the form of a folded portion 139. Specifically, when the battery casing 13 is folded, the rounded shape of the bridge 136 can also be unfolded to a certain extent, but the marks of the bridge 136 will remain on the secondary battery 1, and these marks will become the folded portions 139. Therefore, the bridge 136 and the folded portions 139 of the battery casing 13 can correspond to each other.

[0220] For example, such as Figure 15 As shown, when the rounded shape of the bridge 136 is not fully unfolded, the folded portion 139 includes a groove 1391 recessed into the inner side of the secondary battery 1. In this case, since the curvature of the folded portion 139 is less than that of the bridge 136, the folded portion 139 can have a larger radius of curvature.

[0221] Because bridge 136 has a curved surface and its side outer wall 1381 has a planar shape, their deformation amounts differ. Therefore, when battery casing 13 is folded, the side outer wall 1381 of bridge 136 deforms relatively more, but bridge 136 deforms only relatively less, sufficient to allow the rounded shape to unfold to a certain extent. Then, when battery casing 13 is folded, as... Figure 15 As shown, the increase or decrease in the amount of inclination is switched around the boundary point P1. That is, each boundary point P1 becomes an inflection point. Therefore, the fold 139 can be formed as a surface between two boundary points P1, i.e., two inflection points.

[0222] Furthermore, when the rounded shape of the bridge 136 is not fully unfolded, the two boundary points P1, that is, the portions corresponding to the two inflection points, can protrude outward to form protrusions. That is, in the folded portion 139, more specifically, in the groove 1391 inserted between them, the protrusions can be formed as a pair of outwardly protruding protrusions.

[0223] Alternatively, even if the rounded shape of the bridge 136 is fully unfolded, like a plane, the boundary point P1 between the bridge 136 and the outer wall 1381 on the side of the bridge 136 is connected to the secondary battery 1 by each of two lines (not shown), and the fold 139 is formed as a plane between these two lines.

[0224] The fold 139 can be visually confirmed from the appearance of the secondary battery 1. And as described above, since the thickness t of the bridge 136 is preferably the distance between the two boundary points P1 of the bridge 136 and the outer side wall 1381 of the bridge 136, the width FW of the fold 139 is the distance between the two boundary points P1. If the rounded shape of the bridge 136 is not fully unfolded, the width FW of the fold 139 is the distance between the two boundary points P1, i.e., the distance between the two inflection points. Alternatively, if the rounded shape of the bridge 136 is fully unfolded, the fold 139 is the distance between the two boundary points P1, i.e., the distance between the two lines.

[0225] The width FW of the fold 139 does not exceed the length of the bridge 136 and can be from 1 mm to 3.2 mm, specifically from 1 mm to 1.6 mm. As mentioned above, the width FW of the fold 139 can be measured directly with a ruler, but it can also be measured with a magnifying glass, or with a 3D camera or a laser 2D line sensor. That is, the width FW can be measured by various methods without limitation.

[0226] According to the prior art, the bridge 336 has a relatively thick thickness t' and the folded portion 339 has a relatively large width, thus the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10 is also relatively large. However, according to an embodiment of the present invention, since the width FW of the folded portion 139 can be reduced, the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10 can also be reduced. Therefore, the energy density relative to the volume of the secondary battery 1 can be increased.

[0227] Furthermore, due to the low formability of the soft film in the prior art, the protrusions protrude outwards quite a bit. However, according to embodiments of the present invention, the protrusions can be made relatively small, and the flatness of the fold 139 or the outer wall 1381 of the fold 139 can be improved.

[0228] Specifically, the distance p between the innermost portion of the groove 1391 and the outermost portion of the protrusion can be defined as the flatness. In the case of battery casings according to the prior art, the flatness is formed to be 1 mm or more, or even 1.5 mm. On the other hand, according to embodiments of the present invention, the flatness p can be formed to be 0.8 mm or less, preferably 0.3 mm or less. Therefore, the energy density relative to the volume of the secondary battery 1 can be further increased.

[0229] Figure 16 This is an enlarged schematic diagram of the cup portion 133 and the mold edge 1621 according to another embodiment of the present invention.

[0230] According to an embodiment of the present invention, two molding portions 211 are formed adjacent to each other on the mold 21, and a partition wall 212 may be formed between the two molding portions 211. Therefore, when the soft film 135 is formed, two cup portions 133 are formed in one soft film 135, and a bridge 136 is also formed together between the two cup portions 133. That is, one cup portion 133 is formed in each of the first housing 131 and the second housing 132.

[0231] However, according to another embodiment of the invention, only one molding portion 211 is formed on the mold 21, and no partition wall is present. Therefore, when the soft film 135 is formed, a cup portion 133 is formed in one soft film 135, and there are no bridges. That is, the cup portion 133 is formed only in the first housing 131.

[0232] According to another embodiment of the invention, at least one punch edge 161a of the cup portion 133 is rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, at least one of the punch edges 161a of the cup portion 133 may be rounded with a radius of curvature of less than 1 mm, specifically less than 0.7 mm. As a result, based on the case of molding two cup portions 133, as the formability of the soft film 135 is improved, even if the cup portions 133 are molded to a certain depth, for example, to a depth D of more than 3 mm, specifically more than 7 mm, and more specifically more than 10 mm, cracks can be prevented from forming in the punch edges 161a of the cup portions 133.

[0233] In particular, according to another embodiment of the invention, such as Figure 16 As shown, among the plurality of punch edges 161a, the second housing 132a-side punch edge 1611, which connects the second housing 132a-side outer wall 1381a facing the second housing 132a to the bottom 1332, can be rounded with a radius of curvature corresponding to 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the second housing 132a-side punch edge 1611a can be rounded with a radius of curvature of 1 mm or less, specifically 0.7 mm or less.

[0234] Furthermore, the punch edge 1612 on the mold edge 162 side can also be formed, and simultaneously rounded to have a radius of curvature of 1 / 20 to 1 / 6 of the depth D of the cup portion 133. Specifically, the punch edge 1612 on the mold edge 162 side can be formed to have a radius of curvature of 1 mm or less, particularly 0.7 mm or less. In this case, at the boundary point P2 between the punch edge 161a and the outer wall 138, the inclination is preferably continuous.

[0235] In the following description of another embodiment of the invention, content that is repeated in one embodiment will be omitted. However, this is for ease of explanation and is not intended to limit the scope of the claims.

[0236] Figure 17 This is a schematic diagram showing the folded state of the battery casing 13a according to another embodiment of the present invention. Figure 18 This is a schematic diagram showing the folded state of the battery casing 13a according to another embodiment of the present invention.

[0237] The outer wall 138 has an upper end facing the opening of the cup portion 133, and the second housing 132a, side 134, and degassing portion 137 extend to the outside of the cup portion 133. At this time, the mold edge 162 connecting the upper end of the outer wall 138 with the second housing 132a, side 134, or degassing portion 137 can be rounded with a radius of curvature corresponding to 1 / 6 to 1 / 20 of the depth D of the cup portion 133. Specifically, the mold edge 162 can be formed with a radius of curvature of 1 mm or less, particularly with a radius of curvature of 0.7 mm or less.

[0238] That is, according to another embodiment of the present invention, such as Figure 17 As shown, there is no bridge in the battery casing 13a, and the mold edge 1621 connects the cup portion 133 of the first casing 131 to the second casing 132a. For this purpose, the edge 213 of the mold 21 can be rounded with a radius of curvature obtained by subtracting the thickness of the soft-film 135 from the mold edge 162. For example, if the thickness of the soft-film 135 is 0.2 mm, the edge 213 of the mold 21 can be rounded with a radius of curvature of 0.8 mm or less, specifically 0.5 mm or less.

[0239] Furthermore, with the gap CL reduced to 0.5 mm or less, the outer wall 138a of the cup portion 133 can be formed in an approximately vertical state. For example, as Figure 16 As shown, the mold edge vertical line V4 passes through the boundary point P1 between the mold edge 1621 and the outer wall 1381a of the second housing 132a and is perpendicular to the bottom 1332. The edge vertical line V2 passes through the boundary point P2 between the punch edge 1611a of the second housing 132a and the outer wall 1381a of the second housing 132a and is perpendicular to the bottom 1332. The gap CL, which is the vertical distance between the mold edge vertical line V4 and the edge vertical line V2, can be less than 0.5 mm, specifically less than 0.35 mm.

[0240] Furthermore, the electrode assembly 10 is accommodated such that one end of the electrode 101 is positioned between the edge vertical line V2 and the reference vertical line V3, the reference vertical line V3 being 0.75 mm, specifically 0.5 mm, from the edge vertical line V2 and perpendicular to the bottom 1332.

[0241] Therefore, according to another embodiment of the present invention, based on the case of molding two cup portions 133, as the formability of the soft film 135 is improved, even if the cup portions 133 are molded to a certain depth, for example, to a depth D of 3 mm or more, specifically 7 mm or more, and more specifically 10 mm or more, cracks can be prevented from appearing in the punch edge 161a and mold edge 162 of the cup portions 133. Furthermore, the outer wall 138 of the cup portions 133 can be formed in an approximately vertical state, such that the angle of inclination with the bottom 1332 is 90° to 95°, specifically 90° to 93°, and while preventing damage to the motor 101, the volume ratio of the electrode assembly 10 to the cup portions 133 can be further increased, thus increasing the energy efficiency relative to volume.

[0242] Figure 19 This is an enlarged view of a groove 1391a formed in a battery casing 13 according to another embodiment of the present invention.

[0243] According to another embodiment of the present invention, when the battery casing 13a is folded to manufacture the secondary battery 1a, the mold edge 1621 on the second casing 132a side becomes a folded portion 139a. Specifically, when the battery casing 13a is folded, the rounded shape of the mold edge 1621 can also be unfolded, but the traces of the mold edge 1621 remain in the secondary battery 1a, and these traces can become folded portions 139a. Therefore, the mold edge 1621 and the folded portion 139a on the second casing 132a side of the battery casing 13a correspond to each other.

[0244] For example, such as Figure 19 As shown, when the rounded shape of the mold edge 1621 is not fully unfolded as shown in the figure plane, the folded portion 139a includes a groove 1391a that is recessed into the inner side of the secondary battery 1a. In this case, since the folded portion 139a has a smaller curvature than the mold edge 1621, the folded portion 139a can have a larger radius of curvature.

[0245] Because the mold edge 1621 has a curved surface and the outer wall 1381a of the mold edge 1621 has a planar shape, their deformation amounts differ. Therefore, when the battery casing 13 is folded, the outer wall 1381a of the mold edge 1621 deforms relatively more, but the mold edge 1621 deforms only relatively less, which is sufficient to allow the rounded shape to unfold to a certain extent. Then, when the battery casing 13 is folded, as... Figure 19 As shown, the increase or decrease in the amount of tilt is switched around the boundary point P1. That is, each boundary point P1 becomes an inflection point. Therefore, the fold 139a can be formed as a curved surface between the two boundary points P1, that is, between the two inflection points.

[0246] Alternatively, even if the rounded shape of the mold edge 1621 is fully unfolded, the boundary point P1 between the mold edge 1621 and the outer wall 1381 of the second housing 132a and the boundary point between the mold edge 1621 and the second housing 132a will form two lines (not shown) in the secondary battery 1a, and the folded portion 139a will be formed as a plane between the two lines.

[0247] The width FW of the fold 139 does not exceed the length of the mold edge 1621, and can be from 1mm to 3.2mm, especially from 1mm to 1.6mm.

[0248] Figure 20 This is a schematic diagram showing the state of the battery casing 33 before the degassing portion 337 is cut off, according to the prior art.

[0249] The bridge 136 of the battery casing 13 is folded to form a fold 139 on one side of the secondary battery 1, which integrally connects the first casing 131 and the second casing 132. However, 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 side 134 of the cup portion 133 is also slightly stretched overall. Therefore, when the bridge 136 is folded, the slight elongation of the side 134 is accumulated and thus visually appears while protruding outward from both ends of the fold 139. This is referred to as bat ears 35 or 15.

[0250] The dimensions of the bat ear 35 vary depending on the thickness t' of the bridge 336, the clearance CL', the radius of curvature R2' of the punch edge 361 of the cup portion 333, and the cup portion 333D'. That is, the thicker the bridge 336, the larger the clearance CL', the larger the radius of curvature R2' of the punch edge 361 of the cup portion 333, and the larger the size of the bat ear 35. However, in the prior art, there are limitations in improving the thickness t' of the bridge 336, the radius of curvature R2' of the punch edge 361 of the cup portion 333, and the clearance CL'. Therefore, as... Figure 20 As shown, the size of the bat ear 35 is quite large, which limits the ability to reduce the size of the bat ear.

[0251] When the size of the bat-ear 35 is made too large, the unnecessary volume of the secondary battery 3 increases further, thus causing errors between the designed and actual values ​​of the shape and size of the secondary battery 3. Therefore, when assembling the secondary battery 3 into the battery module 5 (such as...), Figure 27 As shown, assembly is not easy, and considering the bat ears 35, there is a problem that the size of the secondary battery 3 must be designed to be very 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.

[0252] As described above, the soft-pack battery case 13 according to an embodiment of the present invention may include: a cup portion 133, in which a receiving space 1331 for receiving an electrode assembly 10 is provided; and a degassing portion 137, which is formed on one side of the cup portion 133 to discharge the gas generated in the cup portion 133 through a vent hole H.

[0253] Furthermore, in the process of sealing the side 134, a forming process and a degassing process can be performed. Specifically, after the electrode assembly 10 is housed in the cup portion 133, the corner 1371 included in the degassing portion 137 in the battery housing 13 is opened, and the remaining side 134 is sealed. When the edge of the battery housing 13 is opened to form an opening, electrolyte is injected into the battery housing 13 through the opening.

[0254] After the electrolyte is injected into the battery casing 13, the degassing section 137 is first sealed to form a temporary sealing unit 1340. Since the sealing section 1341 is formed by a secondary sealing of the degassing section 137 later, it is preferable to form the temporary sealing section 1340 in the degassing section 137 near the edge 1371.

[0255] Afterwards, the forming process can be performed. The forming process (activation process) is the process that finally completes the charging so that the secondary battery 1 can supply power. Since the forming process is performed after the temporary sealing part 1340 is formed and the battery casing 13 is completely sealed, the manufacturing of the secondary battery 1 is completed within the predetermined process time by rapidly venting the gas with a high filling rate.

[0256] When the forming process is completed, gas is generated in the battery casing 13. Therefore, vent holes H are punched out in the venting portion 137 of the battery casing 13. Through these vent holes H, the gas is discharged from the inside of the battery casing 13 to the outside. At this time, the injected electrolyte may leak through the vent holes H while the gas is easily discharged. To prevent this, it is preferable to punch out the vent holes H near the temporary sealing portion 1340. When the vent holes H are punched out, a venting process is performed to discharge the gas to the outside of the battery casing 13.

[0257] When the vent H is expelled, the interior of the battery casing 13 reopens, and the internal electrolyte may leak to the outside. Therefore, the sealing portion 1341 is formed by secondary sealing of the boundary between the cup portion 133 and the degassing portion 137. Here, the sealing portion 1341 is formed between the cup portion 133 and the vent H, preferably near the cup portion 133.

[0258] As described above, during the forming and degassing processes, the degassing holes H must be punched out, and both primary and secondary sealing must be performed. Furthermore, during mass production of the secondary battery 1, it is necessary to uniformly manage the specifications and quality of the secondary battery 1. For this purpose, an inspection device 4 including a vision sensor 41 (see reference 4) can be used. Figure 22 Check the battery casing 13 or the secondary battery 1.

[0259] According to existing technology, there are limitations in manufacturing the battery casing 33 and the secondary battery 3 as a whole into a sharp shape. Therefore, when the battery casing 33 is photographed using a visual sensor, the size and position of each component have large errors.

[0260] Specifically, when the manufacturing of the secondary battery 1 is completed later, the battery module 5 can be manufactured by connecting the electrode leads 12 of multiple secondary batteries 1 to each other (e.g., Figure 27 (As shown). Therefore, all positions of the electrode leads 12 formed in the multiple secondary batteries 1 must be constant. However, in the prior art, since the electrode 101 is spaced to a certain extent from the outer wall 338 of the cup portion 333, the electrode assembly 10 can move within the cup portion 333 before the sealing side 134. Therefore, when the secondary battery 3 is mass-produced, even if the volume of the cup portion 333 and the volume of the electrode assembly 10 are constant, the position of the electrode assembly 10 will be slightly different, and therefore the position of the electrode leads 12 will also be slightly different. Therefore, it is necessary to use the inspection device 4 to accurately measure the position of the electrode leads 12.

[0261] Furthermore, in order to punch out the vent H in the correct position and size, and to perform primary and secondary sealing in the correct position and size, the position of the degassing section 137 must be accurately measured. In addition, in order to effectively manage the overall weight of the multiple secondary batteries 1, the positions of the battery casing 13 or the various components of the secondary battery 1 (e.g., side 134, fold 139, and insulating portion 14 protruding from the battery casing 13), and consequently the widths between the cup portions 133, must be accurately measured.

[0262] To measure the position of a component, a specific reference line needs to be established and the vertical distance from the reference line to the component to be measured needs to be measured. For example, the electrode assembly 10 is often located within the cup portion 333, typically based on... Figure 20 The bar shown moves in the left-right direction, that is, in the direction toward the folded part 339 and the degassing part 337. Therefore, in order to measure the position of the electrode lead 12, it is necessary to measure the position of the left or right edge of the electrode lead 12, and in order to measure the vertical distance to the left or right edge, a reference parallel to the left or right edge should be established.

[0263] However, in the prior art, the outer wall 338 of the cup portion 333 is not approximately vertical, and the radius of curvature R2' of the punch edge 361 of the cup portion 333 is also relatively large. Therefore, in Figure 20 In the image shown, when the battery casing 33 is photographed using the vision sensor 41, the protruding edge 361 of the cup portion 333 is not clearly visible. Therefore, it is impossible to measure the position of the component based on the protruding edge 361 of the cup portion 333, set the bat ears 35 near the protruding edge 361 as a reference, or have the user manually set the protruding edge 361 of the cup portion 333 as a reference.

[0264] However, since the bat ears 35 are formed by the folding bridge 136 while the peripheral side 134 of the cup portion 133 is also slightly elongated, the size of the bat ears 35 of each of the multiple secondary batteries 1 is slightly different. Therefore, even when the component position is measured using a visual sensor, the deviation in component position between the secondary batteries 3 increases due to the different sizes of the reference bat ears 35, making quality management difficult.

[0265] In particular, even when the position of the electrode leads 12 is measured by photographing the battery casing 33 with a visual sensor, the position of the electrode leads 12 is slightly different, thus presenting a problem of difficulty in connecting the electrode leads 12 when manufacturing the battery module 5. Furthermore, when multiple secondary batteries 1 are stacked or arranged in a line in sequence for manufacturing the battery module 5, the position of the cup portion 333 is incorrect, thus also presenting a problem of reduced alignment of the multiple secondary batteries 1.

[0266] The secondary battery 3 is housed in a separate casing 51 (see reference). Figure 27 When battery module 5 is manufactured in the same way as the battery module 5, if the deviation of the measured value is large, the design tolerance is unnecessarily set to be large when designing the housing 51, and therefore there is also the problem that the energy density relative to the volume of battery module 5 is reduced.

[0267] Figure 21 This is a schematic diagram showing the state of the battery casing 13 before the degassing portion 137 is cut off, according to an embodiment of the present invention. Figure 22 This is a block diagram of the inspection device 4 according to an embodiment of the present invention.

[0268] According to embodiments of the present invention, such as Figure 21 As shown, with the improved formability of the soft film 135, the thickness t of the bridge 136 can be made thinner, and the radius of curvature R2 of the edge 1611 of the cup portion 133 and the gap CL can be made smaller, further reducing the size of the bat ear 15. Therefore, the secondary battery 1 can be easily assembled into the battery module 5, and the unnecessary volume of the secondary battery 1 is reduced, thus increasing the energy density relative to volume.

[0269] Furthermore, according to embodiments of the present invention, such as Figure 21 As shown, since the protruding edge 1611 of the cup portion 133 is clearly visible in the captured image of the battery casing 13, the inspection device 4 can automatically set the protruding edge 161 of the cup portion 133 as the reference line ST. Based on the protruding edge 161 of the cup portion 133, the distances to each component of the battery casing 13 or the secondary battery 1 can be accurately measured. Furthermore, the width CW between the cup portions 133 can be measured accurately. Therefore, the positions of the components of the battery casing 13 or the secondary battery 1 can be accurately measured to reduce measurement errors and decrease deviations between the secondary batteries 1.

[0270] Therefore, the inspection device 4 for the battery casing 13 or the secondary battery 1 according to an embodiment of the present invention includes: a vision sensor 41 for capturing images of the battery casing 13 to obtain images of the battery casing 13 or the secondary battery 1; a contour extraction unit 421 for extracting the contours of the components of the battery casing 13 or the secondary battery 1 from the images; an image analysis unit 422 for analyzing the images to detect the contours corresponding to the punch edge 161 of the cup portion 133, wherein a receiving space 1331 for accommodating the electrode assembly 10 in the battery casing 13 is provided in the cup portion 133; a reference line setting unit 423 for setting the contours corresponding to the punch edge 161 as a reference line ST; and a distance calculation unit 424 for calculating the distance from the reference line ST to the component.

[0271] Furthermore, the inspection method for the battery casing 13 or the secondary battery 1 according to an embodiment of the present invention includes: a step of taking a picture of the battery casing 13 to obtain an image of the battery casing 13 or the secondary battery 1; a step of extracting the contour of the components of the battery casing 13 or the secondary battery 1 from the image by means of a contour extraction unit 421; a step of analyzing the image to detect the contour corresponding to the punch edge 161 of the cup portion 133, wherein a receiving space 1331 for accommodating the electrode assembly 10 in the battery casing 13 is provided in the cup portion 133; a step of setting the contour corresponding to the punch edge 161 as a reference line ST; and a step of calculating the distance from the reference line ST to the component.

[0272] Specifically, such as Figure 22 As shown, the inspection device 4 includes a vision sensor 41 and a controller 42. Furthermore, the aforementioned components can be connected to each other via a busbar (not shown) for communication. All components located in the control unit 42 can be connected to the busbar via at least one interface or adapter, or can be directly connected to the busbar. Additionally, the busbar can be connected to other subsystems besides the aforementioned components. The busbar includes a memory busbar, a memory controller, a peripheral busbar, and a local busbar.

[0273] The vision sensor 41 acquires images by photographing a specific area to receive image signals of that specific area. Generally, the vision sensor 41 includes an imaging device, such as a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) image sensor. Specifically, in the vision sensor 41 according to an embodiment of the invention, the battery housing 13 is photographed after the bridge 136 of the battery housing 13 is folded to obtain images of the battery housing 13 or the various components of the secondary battery 1. These components include the cup portion 133, the degassing portion 137, the electrode leads 12, the batwing portion 15, the side 134, the folding portion 139, and the insulating portion 14 described above. Then, the degassing portion 137 is cut off later to complete the manufacturing of the secondary battery 1. Therefore, if the vision sensor 41 photographs the battery housing 13 before cutting off the degassing portion 137, images of the battery housing 13 and the electrode leads 12 can be obtained; and if the battery housing 13 is photographed after cutting off the degassing portion 137, an image of the secondary battery 1 can be obtained.

[0274] The controller 42 receives image signals obtained by the vision sensor 41 to identify the positions of various components of the battery casing 13 or the secondary battery 1 from the image signals. The control unit 42 includes a contour extraction unit 421, an image analysis unit 422, a baseline setting unit 423, and a distance calculation unit 424. It is preferable to use a central processing unit (CPU), a microcontroller unit (MCU), or a digital signal processor (DSP) as the control unit 42, but the present invention is not limited thereto; for example, various logic operation processors can be used.

[0275] Contour extractor 421 extracts the contours of each component of battery casing 13 or secondary battery 1 from the image received by vision sensor 41. At this time, contour extraction unit 421 can extract the contours of all components appearing in the image, but is not limited to this; a region of interest (ROI) can be set in a portion of the image, or only the contours of components appearing in the ROI can be extracted. To extract the contours, information about the pixels in the image is first extracted, for which a commonly used gradient formula can be used. The contours of battery casing 13 and electrode leads 12 are displayed using the extracted pixel information.

[0276] According to one embodiment of the present invention, the radius of curvature R2 and the gap CL of the punch edge 161 of the cup portion 133 can be made smaller, and since the outer wall 138 of the cup portion 133 is formed in an approximately vertical state, the gradient of the pixel information corresponding to the punch edge 161 of the cup portion 133 in the image is large. Therefore, since the boundary between the contour and the background is clear, the contour corresponding to the punch edge 161 of the cup portion 133 can be clearly extracted.

[0277] The image analysis unit 422 analyzes the image and detects the contour corresponding to the protruding edge 161 of the cup portion 133 within the battery casing 13. To this end, the image analysis unit 422 matches pre-stored reference contour information of the protruding edge 161 of the cup portion 133 with the extracted contour information to detect the contour corresponding to the protruding edge 161 of the cup portion 133. In this case, the image analysis unit 422 can use template matching technology to match the two pieces of information.

[0278] The reference line setting unit 423 can set the contour corresponding to the punch edge 161 as the reference line ST. Since the cup portion 133 includes multiple punch edges 161, multiple contours corresponding to the punch edges 161 are also extracted. Here, in order to accurately measure the position of each component of the battery casing 13 or the secondary battery 1, the reference line setting unit 423 can preferably set the contour corresponding to the punch edge 161 closest to the component to be measured among the multiple punch edges 161 as the reference line ST. In addition, as described above, since the position of the component must be measured at its vertical distance from the reference line ST, the reference line setting unit 423 can set the contour corresponding to the punch edge 161 parallel to the edge of the component to be measured among the multiple punch edges 161 as the reference line ST.

[0279] For example, in order to punch out the vent hole H and perform primary and secondary sealing, the inspection device 4 may need to measure the position of the degassing section 137. In this case, the reference line setting unit 423 can set the profile corresponding to the mold edge 1612 on the side of the die edge 162 that is close to the degassing section 137 and parallel to the edge 1371 included in the degassing section 137 as the reference line ST.

[0280] For example, in order to check whether the positions of the electrode leads 12 are all constant, the inspection device 4 may have to measure the positions of the electrode leads 12. In this case, the reference line setting unit 423 can set the electrode lead 12 side profile corresponding to the fold portion 139 side punch edge 161 that is close to the electrode lead 12 and parallel to the left or right edge of the electrode lead 12 as the reference line ST.

[0281] In addition, in order to measure the width between the cup portions 133, the reference line setting unit 423 can set one of the contours of the two punch edges 161 corresponding to the boundary of the width of the cup portion 133 among the plurality of punch edges 161 as the reference line ST.

[0282] That is, as long as the baseline setting unit 423 accurately measures the position of each component of the battery casing 13 or the secondary battery 1, the baseline setting unit 423 can set various contours as baselines without limitation.

[0283] The distance calculation unit 424 calculates the distance from the reference line ST to each component of the battery casing 13 or the secondary battery 1 in the image. For example, if the contour corresponding to the punch edge 1612 on the mold edge 162 side is set as the reference line ST, the distance calculation unit 424 can calculate the distance from the reference line ST to the edge contained in the degassing section 137. Alternatively, if the contour corresponding to the punch edge 1611 on the folding section 139 side is set as the reference line ST, the distance calculation unit 424 can calculate the distance from the reference line ST to one edge of the electrode lead 12, and can also calculate the distance to the contour corresponding to the punch edge 1612 on the mold edge 162 side.

[0284] The distance calculation unit 424 can use information about the relationship between the number of pixels in a pre-stored image and the actual distance. That is, in the image, the distance calculation unit 424 can include the distance from the baseline ST to each component in the number of pixels, and then calculate the actual distance corresponding to the included number of pixels by using information about the relationship between the number of pixels in a pre-stored image and the actual distance.

[0285] The inspection device 4 may further include a storage unit 44. The storage unit 44 stores programs for processing and controlling the operation of the inspection device 4, as well as various data or received signals generated during the execution of each program. Specifically, reference information about the battery housing 13 may be stored, enabling the image analysis unit 422 to detect the contour corresponding to the punch edge 1611 of the cup portion 133. Here, the reference information about the battery housing 13 includes reference contour information about the punch edge 1611 of the cup portion 133 and reference information about the distance to the battery housing 13 or the components of the secondary battery 1. This can be directly stored in the storage unit 44 by the user, or the inspection device 4 can generate and store the reference information through repeated learning. Furthermore, the storage unit 44 may store information about the relationship between the number of pixels in the image and the actual distance, so that the distance calculation unit 424 can calculate the actual distance from the reference line ST to each component. Additionally, inspection result information of the battery housing 13 to be inspected may also be stored. This storage unit 44 may be built into the inspection device 4, but it may also be configured as a separate storage server. The storage unit 44 includes both non-volatile storage and volatile storage. Non-volatile storage devices can be small, lightweight, and highly resistant to external shocks, such as NAND flash memory, while volatile storage devices can be DDR SDRAM.

[0286] The control unit 42 may further include a fault determination unit 425 to determine whether the battery casing 13 to be inspected is defective. The fault determination unit 425 can compare the reference information about the battery casing 13 stored in the storage unit 44 with the inspection result information of the battery casing 13 to be inspected. If the inspection result information is within the error range of the reference information, the battery casing 13 is determined to be normal. However, if the inspection result information is outside the error range of the reference information, the battery casing 13 is determined to be defective.

[0287] The inspection device 4 may further include a display unit 43 for receiving and displaying image signals. The display unit 43 receives image signals and displays the images to the user. Furthermore, when the contour extraction unit 421 extracts the contour of the battery casing 13, the contour can be displayed on the image, allowing the user to inspect the contour through the display unit 43. The display unit 43 can use various methods, such as a liquid crystal display (LCD), an organic liquid crystal display (OLED), a cathode ray tube (CRT), and a plasma display panel (PDP). Additionally, the display unit 43 is connected to a busbar via a video interface, and data transmission between the display unit 43 and the busbar can be controlled by a graphics controller.

[0288] The inspection device 4 may further include an alarm unit 45, which generates an alarm when the fault determination unit 425 determines that the battery casing 13 is defective. When an alarm is generated, it is preferably an auditory or visual alarm such as the lighting of a light or a warning sound, so that the user can be intuitively aware of the situation.

[0289] Each component of the vision sensor 41, control unit 42, storage unit 44, and display unit 43 described so far can be implemented using software such as tasks, classes, subroutines, processes, objects, execution threads, and programs that execute in a predetermined area of ​​memory, or using hardware such as field-programmable gate arrays (FPGAs) or application-specific integrated circuits (ASICs), or a combination of software and hardware. Components can be included in a computer-readable storage medium, or a portion of a component can be distributed and dispersed across multiple computers.

[0290] Furthermore, each block can represent a module, segment, or portion of code that includes one or more executable instructions for performing a specified logical function. Additionally, in some alternative implementations, the functions mentioned in a block may appear out of order. For example, depending on their respective functions, two consecutively displayed blocks may actually be executed simultaneously, or sometimes they may be executed in reverse order.

[0291] When using the inspection device 4 according to an embodiment of the present invention, since the punch edge 1611 of the cup portion 133 is clearly displayed, the inspection device 4 can automatically set the punch edge 1611 of the cup portion 133 as the reference line ST, and accurately measure the distances to each component of the battery casing 13 based on the punch edge 1611 of the cup portion 133. For example, the size and position of the degassing portion 137 can be measured, and even after the secondary battery 1 is manufactured, the size and position of the cup portion 133, electrode leads 12, batwing ears 15 and side edges 134, folding portions 139 and insulating portions 14 can be accurately identified. Therefore, it is easy to determine whether the secondary battery 1 is defective, and even if the secondary battery 1 is mass-produced, its specifications and quality can be effectively and centrally managed.

[0292] In particular, because the position of the electrode leads 12 is accurately measured, the components can be easily connected to each other when the electrode leads 12 are connected to manufacture the battery module 5. In addition, the position of the cup portion 333 can be accurately measured, so the alignment of the multiple secondary batteries 1 can be improved when multiple secondary batteries 1 are stacked in sequence or arranged in a line to manufacture the battery module 5.

[0293] Figure 23 This is a schematic diagram showing the state in which the degassing portion 137 of the battery casing 13 is cut off to complete the manufacturing of the secondary battery 1 according to an embodiment of the present invention.

[0294] After the battery casing 13 is sealed a second time to form a sealing portion 1341, the degassing portion 137 is cut off by providing a cutting line CT on the outside of the sealing portion 1341. As a result, as Figure 23 As shown, the length of the degassing section 137 can be shortened, and the volume of the secondary battery 1 can be reduced. Through the above steps, the manufacturing of the pouch-type secondary battery 1 is completed.

[0295] In the remaining side 134 after the degassing section 137 is cut off, the electrode leads 12 are not formed to protrude between the multiple sides 134. However, if the side 134 remains unchanged after sealing, the overall volume of the secondary battery 1 increases. Therefore, in order to reduce the energy density relative to volume, it is desirable to fold the side 134.

[0296] like Figure 23 As shown, side 134 may include a sealing portion 1341 and a non-sealing portion 1342. The sealing portion 1341 is the sealed area located on the outer side, and the non-sealing portion 1342 is the unsealed area located on the inner side.

[0297] Specifically, when the sealing portion 1341 is formed by the secondary seal of the battery housing 13, the sealing portion 1341 is not directly connected to the cup portion 133, but can be formed to a certain extent spaced apart. When sealing the side 134, a separate sealing tool (not shown) must be used to apply heat and pressure to the side 134. However, if the side 134 is sealed while the sealing tool is in close contact with the cup portion 133, the sealant layer 1351 disposed inside the side 134 partially melts and leaks into the electrode assembly 10, thereby contaminating the electrode assembly 10. In addition, the heat from the sealing tool may be transferred to the electrode assembly 10, damaging the electrode assembly 10. Therefore, it is preferable to seal the side 134 while the sealing tool is spaced apart from the cup portion 133. Then, the portion sealed by the sealing tool becomes the sealing portion 1341, and the portion not sealed due to the spaced separation between the sealing tool and the cup portion 133 becomes the unsealed portion 1342.

[0298] Figure 24 This is a schematic side view showing the state in which side 334 is folded according to the prior art. Figure 25 This is a schematic top view showing the state in which the side 334 is folded according to the prior art.

[0299] In the prior art, when the side 334 is folded, there is a problem that the side 334 is not fixed and unfolds again at a predetermined angle. Specifically, as described above, the soft film 135 is formed by stacking a sealant layer 1351, a moisture barrier layer 1352, an elongation aid layer 1354, and a surface protective layer 1353. The sealant layer 1351 comprises a first polymer, particularly polypropylene (PP), and therefore exhibits good flexibility and elasticity. Thus, when the side 334 is folded, the restoring force to its original state is large. On the other hand, since the moisture barrier layer 1352 is made of metal, particularly aluminum alloy, after the side 334 is folded, it exceeds the limit of elastic deformation and therefore maintains a large holding force in the folded state.

[0300] However, in the soft-pack film according to the prior art, the thickness of the moisture barrier layer is approximately 30 μm to 50 μm, and the thickness of the sealant layer is approximately 60 μm to 100 μm. That is, the thickness of the moisture barrier layer is much thinner than the thickness of the sealant layer. Therefore, the restoring force is greater than the holding force, and thus the side 334 is not fixed and unfolds again at the predetermined angle. Therefore, there is a problem that the volume of the secondary battery 3 unnecessarily increases due to the side 334.

[0301] To solve this problem, such as Figure 24 and 25As shown, tape 38 is individually attached to side 334. Specifically, tape 38 is attached to both the side 334 of the cup portion 333 and the outer surface of the bottom 3332, thereby securing the side 334 to the cup portion 333 and preventing the side from unfolding again. However, in this case, as... Figure 24 As shown, there is a problem that the overall thickness of the secondary battery 3 increases due to the thickness of the tape 38 itself. In addition, after the process of folding the side 334, an additional process of attaching the tape 38 is required, which consumes a lot of time, increases the number of processes, and degrades the manufacturing yield of the secondary battery 3.

[0302] During degassing, the internal pressure of the cup 133 decreases as gas is discharged from the inside of the battery casing 13 to the outside. In the prior art, the electrode assembly 10 is positioned to be spaced apart from the outer wall 338 of the cup 333 to a certain extent. Therefore, in order to reduce the internal pressure of the cup 333 while reducing the volume of the space 37 between the outer wall 338 of the cup 333 and the electrode assembly 10, the outer wall 338 or the bottom 3332 of the cup 333 can be deformed. In particular, as... Figure 24 As shown, a high-edge phenomenon occurs where the outer wall 338 of the folded portion side of the secondary battery 3 is recessed inward, and the edge 361 of the punch on the folded portion 339 side of the cup portion 333 protrudes outward, increasing its height. Due to this high-edge phenomenon, the secondary battery 3 experiences an unnecessary increase in thickness, resulting in a decrease in energy density relative to volume. Furthermore, the deformation of the outer wall 338 of the folded portion 339 side of the cup portion 333 leads to an unattractive appearance of the secondary battery 3, reducing its marketability. Additionally, the size of the bat ears 15 further increases, and their shape protrudes due to the high-edge phenomenon.

[0303] Figure 26 A schematic side view illustrating the folded state of side 134 according to an embodiment of the present invention.

[0304] According to an embodiment of the invention, in the flexible film 135, since the thickness of the moisture barrier layer 1352 is 50 μm to 70 μm and the thickness of the sealant layer 1351 is 70 μm to 100 μm, the thickness of the moisture barrier layer 1352 becomes thicker than in the prior art. Therefore, since the holding force is further increased when the side 134 is folded, the side 134 can be prevented from unfolding again without attaching a separate adhesive tape 38 to it.

[0305] Therefore, the secondary battery 1 according to an embodiment of the present invention includes: an electrode assembly 10, formed by stacking electrodes 101 and separators 102; and a pouch-type battery housing 13 having a cup portion 133 for accommodating the electrode assembly 10 therein. The pouch-type battery housing 13 includes a side 134 extending outward from the cup portion 133, the side 134 including: a sealing portion 1344 disposed on the opposite outer side and sealed; and a non-sealing portion 1345 disposed on the opposite inner side and not sealed. Therefore, the side 134 is not adhered to the cup portion 133 and folded over the non-sealing portion 1345.

[0306] That is, such as Figure 26 As shown, in the secondary battery 1, after the side 134 is folded towards the cup portion 133, the side 134 does not adhere to the cup portion 133 while maintaining the folded state, and therefore does not unfold. In this case, the side 134 can be folded at an angle of 85° to 95°, particularly at an angle of 88° to 92°. Furthermore, the side 134 can be folded at a position adjacent to the cup portion 133, so that the side 134 can contact the outer wall 138 of the cup portion 133. In particular, as described above, the side 134 may include a sealing portion 1341 disposed on the relatively outer side and thus sealed, and a non-sealing portion 1342 disposed on the relatively inner side so as not to be sealed. And, when the side 134 is folded, preferably, the non-sealing portion 1342, which is relatively closer to the cup portion 133, is folded. As a result, the unnecessary volume of the secondary battery 1 can be further reduced. However, even in this case, the side 134 and the cup portion 133 do not adhere to each other, and the holding force of the side 134 increases to maintain the folded state.

[0307] When two cup portions 133 are formed on the soft membrane 135, the depth D of the cup portions 133 can be shallower than when only one cup portion 133 is formed. This is because, as described above, not only are the cup portions 133 elongated in a concentrated manner, but the peripheral sides 134 of the cup portions 133 are also slightly elongated overall. However, if the width of the side 134 is greater than the depth D of the cup portion 133, then when the side 134 is folded only once, the outer end 1343 of the side 134 protrudes further outward than the bottom 1332 of the cup portion 133.

[0308] Therefore, if two cup portions 133 are formed on the soft membrane 135, then as shown in the figure, it is possible to use... Figure 26The diagram illustrates a double-sided folding (DSF) method where the side 134 is folded twice. Specifically, the side 134 may include a first fold portion 1344 and a second fold portion 1345. The first fold portion 1344 is the portion folded relatively close to the outer end 1343, and the second fold portion 1345 is the portion folded relatively close to the cup portion 133. Therefore, after the side 134 is folded for the first time based on the first fold portion 1344, the side 134 can be folded a second time based on the second fold portion 1345. In this case, the first fold portion 1344 may be provided on the sealing portion 1341 at the side 134, and the second fold portion 1345 may be provided on the non-sealing portion 1342 at the side 134. Furthermore, the side 134 may be folded at an angle of 170° to 180° in the first fold portion 1344, particularly at an angle of 180°. Furthermore, the second fold portion 1345 may be folded at an angle of 85° to 95°, particularly at an angle of 88° to 92°. This prevents the outer end 1343 of the side 134 from protruding further outward than the bottom 1332 of the cup portion 133.

[0309] According to an embodiment of the present invention, since the electrode assembly 10 can be disposed very close to the outer wall 138 of the cup portion 133, the unnecessary volume of the cup portion 133 is reduced. Therefore, even if the internal pressure of the cup portion 133 decreases due to the degassing process, deformation of the outer wall 138 or the bottom 1332 of the cup portion 133 can be prevented. That is, as Figure 26 As shown, this can prevent the occurrence of high edge phenomena, and therefore the energy density relative to the volume will not decrease.

[0310] Figure 27 This is a schematic diagram of battery module 5 according to an embodiment of the present invention.

[0311] Because medium to large electronic devices such as automobiles require high output, a large number of secondary batteries 1 are needed. To facilitate the movement and installation of these secondary batteries 1, battery modules 5 can be manufactured. When multiple secondary batteries 1 are installed in the battery module 5, a stable power supply can be provided to the external system.

[0312] In order to generate electricity in the electrode assembly 10 of the secondary battery 1, a chemical reaction occurs between the electrode 101 and the electrolyte, and heat is generated in the process. However, when the ambient temperature rises excessively due to heat, there is a problem that the circuit of the electronic device on which the secondary battery 1 is installed may malfunction or the lifespan of the electronic device may be shortened. Therefore, the battery module 5 includes a cooling system for cooling the secondary battery 1. Cooling systems are mainly divided into water-cooled systems that use cooling water to cool the secondary battery and air-cooled systems that use air to cool the secondary battery. Among them, water-cooled cooling systems have higher cooling efficiency than air-cooled cooling systems and are therefore more widely used.

[0313] The cooling system includes a cooling plate that directly cools the secondary battery 1, and separate flow paths are formed inside the cooling plate to allow cooling water to flow. Furthermore, as the thickness and length of the flow paths increase, the surface area can be increased, thereby increasing cooling efficiency.

[0314] To manufacture the battery module 5, firstly, multiple secondary batteries 1 are manufactured, then these secondary batteries 1 are connected to each other and housed in a casing 51. In this case, the secondary batteries 1 can be arranged in a line and stacked. Figure 27 As shown, when the secondary battery 1 is housed in the housing 51, the long side of the secondary battery 1 can face downwards, and a cooling plate (not shown) can be formed on the lower surface of the housing 51. Therefore, the cooling efficiency can be improved by cooling the cooling plate from the long side of the secondary battery 1.

[0315] A folded portion 139, formed by folding the bridge 136, is formed on one side of the secondary battery 1, and a side edge 134, which is the area remaining after the degassing portion 137 is cut off, is formed on the other side. However, if the cooling plate is cooled from the side where the side edge 134 is formed from one of the multiple surfaces of the secondary battery 1, the distance between the cooling plate and the electrode assembly 10 increases through the side edge 134, thereby reducing the cooling efficiency. Therefore, it is preferable to cool the cooling plate from the side where the folded portion 139 is formed from the long side surface of the secondary battery 1. For this purpose, when the secondary battery 1 is housed in the housing 51, the folded portion 139 can be housed downwards in the direction toward the cooling plate.

[0316] Figure 28 This is an enlarged front view showing the state in which the secondary battery 3, according to the prior art, is housed in the casing 51 of the battery module 5. Figure 29 This is an enlarged side view showing the state in which a secondary battery 3, according to the prior art, is housed in the housing 51 of a battery module 5.

[0317] As mentioned above, there are limitations in reducing the size of the bat ear 35 in the prior art. In particular, while forming the depth D' of the cup portion 333 to be sufficiently deep (e.g., less than 6.5 mm), there are limitations in reducing the size of the bat ear 35 to a specific value (e.g., less than 1.5 mm).

[0318] Furthermore, in the prior art, the angle θ' formed between the fold 339 and the inner edge 35a of the bat ear 35 is less than 151 degrees.

[0319] Here, angle θ' can represent the angle formed by the virtual first line L1 corresponding to the fold 339 and the virtual second line L corresponding to the inner edge 35a of the bat ear 35. Specifically, the first line L1 and the second line L2 can be determined by image analysis. For example, the first line L1 and the second line L2 can be extracted by connecting multiple edge points identified within the region of interest (ROI) in the visual device. Therefore, even when the fold 339 or the inner edge 35a of the bat ear 35 is partially bent or folded, the first line L1 and the second line L2 can be clearly defined. Since image analysis is a well-known technique, its detailed description will be omitted.

[0320] Therefore, as Figure 28 As shown, when the secondary battery 3 is housed in the housing 51, the housing 51 and the fold 339 are spaced apart by a large gap d' (e.g., greater than 1.5 mm) via the batwing 35. Therefore, this gap d' may interfere with the cooling of the cooling plate, potentially reducing cooling efficiency. To address this issue, a heat transfer material 52 is injected into the space between the cooling plate and the fold 339 of the secondary battery 1, thus allowing the cooling plate to cool the fold 139 via the heat transfer material 52. For example, the heat transfer material 52 can be a thermally conductive grease.

[0321] However, if the size of the bat ear 15 is large, the cost increases due to the need to inject a large amount of heat transfer material 52, and the cooling efficiency remains low due to the large gap d' between the cooling plate and the fold 139.

[0322] Furthermore, when the degassing process is carried out through the degassing hole H, such as Figure 29 As shown, while the internal pressure of the battery casing 33 decreases, the folded portion 339 of the battery casing 33 comes into close contact with the electrode assembly 10. However, the prior art has limitations in reducing the gap CL', and the width of the folded portion 339 is also relatively large. Therefore, the space 37 between the outer wall 338 of the cup portion 333 and the electrode assembly 10 is relatively large, resulting in a decrease in energy density relative to the volume of the secondary battery 3. Furthermore, since the distance between the electrode assembly 10 and the thermal grease 52 also increases, there is a further decrease in cooling efficiency.

[0323] Figure 30 This is an enlarged front view showing the state in which the secondary battery 1 according to an embodiment of the present invention is housed in the housing 51 of the battery module 5. Figure 31 This illustrates a secondary battery according to an embodiment of the present invention. Figure 1 An enlarged side view of the battery module 5 housed in its casing 51.

[0324] According to an embodiment of the present invention, a pouch-type secondary battery 1 includes: an electrode assembly 10, wherein electrodes 101 and separators 102 are stacked in the electrode assembly; and a pouch-type battery housing 13 having a cup portion 133 therein for accommodating the electrode assembly 10, wherein the battery housing 13 includes: a first housing 131 and a second housing 132, wherein the cup portion 133 is formed in at least one of the first housing 131 and the second housing 132; a folding portion 139 for integrally connecting the first housing 131 and the second housing 132; and bat ears 15 protruding outward from a portion of both ends of the folding portion 139, wherein the length d of the bat ears 15 is less than 1.5 mm.

[0325] Furthermore, the angle θ between the fold 139 and the inner edge 15a of the bat ear 15 can be greater than 151 degrees. Alternatively, the angle θ can be less than 180 degrees. And, when the angle θ is 180 degrees, it may indicate a state where the bat ear 15 is not present.

[0326] Here, angle θ can represent the angle formed by the virtual first line L1 corresponding to the fold 139 and the virtual second line L2 corresponding to the inner edge 15a of the bat ear 15. The description of the first line L1 and the second line L2 can be derived using the above description. According to an embodiment of the present invention, the battery module 5 includes: a pouch battery housing 13, wherein an electrode assembly 10 is housed in a cup portion 33 formed in the pouch battery housing 13, and electrodes 101 and separators 102 are stacked in the electrode assembly 10; and a housing 51, in which a secondary battery 1 is housed, wherein the battery housing 13 includes: a first housing 131 and a second housing 132, each having a cup portion 133 formed therein; a fold 139 for integrally connecting the first housing 131 and the second housing 132; and bat ears 15, protruding outward from a portion of both ends of the fold 139, wherein the length d of the bat ears 15 is 1.5 mm or less.

[0327] As described above, by folding the bridge 136, the bat ear 15 is formed to protrude outward from a portion of both ends of the fold 139. According to one embodiment of the invention, the length of the bat ear 15 can be less than 1.5 mm, particularly less than 1 mm. The length of the bat ear 15 can be the length measured from the outer wall 1381 of the fold 139 side to the outermost end of the bat ear 15. In this case, as described above, due to the gap CL, the outer wall 1381 of the fold 139 side can have an inclination angle of 90° to 95° from the bottom 1332. Taking this into consideration, as an example of measuring the bat ear, the length of the bat ear 15 can be the length measured from the outermost protrusion of the outer wall 1381 of the fold 139 side to the outermost end of the bat ear 15.

[0328] The length of the bat ear 15 can be measured by directly contacting the secondary battery 1 with a ruler or vernier caliper, or by measuring it in a non-contact manner using a laser displacement sensor or a vision sensor.

[0329] As described above, the method for measuring the length of a bat's ear has been used as an example. However, situations where the method is limited to the aforementioned measurement method are not included within the scope of this invention. The length of a bat's ear can be considered within the meaning of this invention as long as it falls within the scope of the claims and the spirit of this invention.

[0330] According to an embodiment of the present invention, as the formability of the soft film 135 is improved, the thickness t of the bridge 136 is formed to be thinner, and the radius of curvature R2 and the gap CL of the punch edge 1611 of the cup portion 133 can be formed to be smaller.

[0331] Therefore, while molding the depth D of the cup portion 133 to 3 mm or more, particularly 6.5 mm or more, the length d of the batwing ear 15 can be further reduced to 1.5 mm or less, particularly 1 mm or less. Therefore, as... Figure 30 As shown, the distance d between the housing 51 and the folded portion 139 can be reduced to less than 1.5 mm. Therefore, the thickness of the heat transfer material 52 inside the housing 51 can be less than 1.5 mm, thus further reducing the amount of heat-conducting grease 52 injected, thereby reducing costs and improving cooling efficiency.

[0332] In addition, such as Figure 31 As shown, the gap CL can be reduced, which can reduce the width FW of the folded portion 139. Therefore, the space 17 between the outer wall 138 of the cup portion 133 and the electrode assembly 10 is reduced, thus increasing the energy density relative to the volume of the secondary battery 1. Furthermore, since the distance between the electrode assembly 10 and the thermal grease 52 is also reduced, the cooling efficiency can be further improved.

[0333] Those skilled in the art will understand that the invention can be implemented in other specific forms without altering its technical spirit or essential characteristics. Therefore, it should be understood that the above embodiments are considered exemplary and not restrictive. Consequently, the scope of the invention is defined by the following claims, rather than by the foregoing detailed description and exemplary embodiments herein. Various modifications made within the scope of equivalent concepts of the claims and within the scope of the claims should be interpreted as being within the scope of the invention.

[0334] [Explanation of reference numerals in the attached figures]

[0335] 1: Secondary battery 2: Molding device

[0336] 3: Secondary batteries based on existing technology

[0337] 4: Inspection device

[0338] 5: Battery Module 10: Electrode Assembly

[0339] 11: Electrode sheet 12: Electrode lead

[0340] 13: Battery casing 14: Insulation part

[0341] 15: Bat ears 16: Edges

[0342] 17: Space; 21: Mold; 22: Punch; 33: Battery casing according to prior art

[0343] 35: Bat ears according to the prior art 36: Edges according to the prior art

[0344] 37: Space according to the prior art 38: Tape according to the prior art

[0345] 41: Vision sensor 42: Controller

[0346] 43: Display Unit 44: Storage Unit

[0347] 45: Alarm unit; 51: Housing

[0348] 52: Thermal grease; 101: Electrode

[0349] 102: Separator; 111: Positive terminal piece

[0350] 112: Negative terminal piece; 121: Positive terminal lead

[0351] 122: Negative lead; 131: First housing

[0352] 132: Second shell 133: Cup portion

[0353] 134: Side panel; 135: Soft wrapping film

[0354] 136: Bridge; 137: Degassing section

[0355] 138: Outer wall; 139: Folding section

[0356] 161: Punch edge; 162: Mold edge

[0357] 163: Thickness edge 164: Corner

[0358] 211: Molding Department 212: Adjacent

[0359] 213: Mold edge; 221: Punch edge

[0360] 333: Cup portion according to the prior art; 334: Side portion according to the prior art.

[0361] 336: Bridge according to the prior art; 337: Degassing section according to the prior art.

[0362] 338: Outer wall according to the prior art 339: Folding part according to the prior art

[0363] 361: Punch edge according to the prior art 362: Mold edge according to the prior art

[0364] 421: Contour extraction unit; 422: Image analysis unit

[0365] 423: Baseline setting unit; 424: Distance calculation unit

[0366] 425: Fault Judgment Department; 1021: Peripheral Department

[0367] 1331: Storage space 1332: Bottom

[0368] 1333: Outer wall; 1340: Temporary sealing section

[0369] 1341: Sealing part; 1342: Non-sealing part

[0370] 1343: Outer end; 1344: First fold section

[0371] 1345: Second fold; 1351: Sealant layer

[0372] 1352: Moisture barrier layer; 1353: Surface protective layer

[0373] 1354: Elongated auxiliary layer; 1371: Edge

[0374] 1381: Outer wall of bridge side; 1382: Outer wall of degassing section side.

[0375] 1391: Groove; 1611: Edge of bridge-side punch

[0376] 1612: Edge of the degassing section side punch; 1613: Edge of the first punch.

[0377] 1614: Edge of the second punch

Claims

1. A pouch-type secondary battery comprising: an electrode assembly in which an electrode and a separator are stacked; a pouch-type battery case including a cup portion configured to accommodate the electrode assembly in the pouch-type battery case, wherein the pouch-type battery case includes a side edge extending to an outside of the cup portion, and the side edge includes: a sealed portion provided at a relatively outer side and sealed; and an unsealed portion provided at a relatively inner side and unsealed, wherein the side edge is not adhered to the cup portion, and the side edge is folded at the unsealed portion, wherein the battery case is made by molding a pouch film, and the pouch film includes: a sealant layer made of a first polymer and formed at an innermost layer; a surface protection layer made of a second polymer and formed at an outermost layer; and a moisture barrier layer stacked between the surface protection layer and the sealant layer, wherein the moisture barrier layer is formed as an aluminum alloy thin film having a thickness of 50 to 80 μm and a particle diameter of 10 to 13 μm, and the sealant layer has a thickness of 60 to 100 μm.

2. The pouch-type secondary battery according to claim 1, wherein The side edge is in contact with an outer wall of the cup portion and is folded.

3. The pouch-type secondary battery according to claim 1, wherein The side edge is folded at an angle of 85 to 95°.

4. The pouch-type secondary battery according to claim 1, wherein The side edge includes: a first folding portion folded at a position relatively close to an outer end; and a second folding portion folded at a position relatively close to the cup portion.

5. The pouch-type secondary battery according to claim 4, wherein The first folding portion is provided on the sealed portion, and the second folding portion is provided on the unsealed portion.

6. The pouch-type secondary battery according to claim 4, wherein The side edge is folded at an angle of 170 to 180° with respect to the first folding portion.

7. The pouch-type secondary battery according to claim 4, wherein The side edge is folded at an angle of 85 to 95° with respect to the second folding portion.

8. The pouch-type secondary battery according to claim 7, wherein The side edge is folded at an angle of 88 to 92° with respect to the second folding portion. 9.The pouch-type secondary battery of claim 1, wherein The aluminum alloy thin film includes AA8021 aluminum alloy. 10.The pouch-type secondary battery of claim 1, wherein, The aluminum alloy thin film contains 1.3 to 1.7 wt% of iron and 0.2 wt% or less of silicon. 11.The pouch-type secondary battery of claim 1, wherein The moisture barrier layer has a thickness of 55 to 65 μm, and The sealant layer has a thickness of 75 to 85 μm. 12.The pouch-type secondary battery according to claim 1, further comprising an elongation assistance layer made of a third polymer and stacked between the surface protection layer and the moisture barrier layer. 13.The pouch-type secondary battery of claim 12, wherein The elongation assistance layer has a thickness of 20 to 50 μm. 14.The pouch-type secondary battery of claim 1, wherein, The area of the electrode assembly is 15000mm 2 up to 100000mm 2 .

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