Apparatus and method for forming pouch, and pouch for secondary battery

Abstract

The pouch forming apparatus of the present invention comprises: a pouch forming unit for forming an accommodating unit for accommodating an electrode assembly in a pouch film; and a water vapor injection unit for injecting water vapor toward the pouch film to increase the water content of a resin layer included in the pouch film, thereby increasing the elongation. As a result, breakage can be prevented when the bag film is formed.

Description

Equipment and methods for forming bags, and bags for secondary batteries. Technical Field

[0001] Cross-references to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2023-0141479, filed in Korea on October 20, 2023, and Korean Patent Application No. 10-2024-0142458, filed in Korea on October 17, 2024, the disclosures of which are incorporated herein by reference.

[0003] This disclosure relates to molding equipment and methods for forming a receiving portion with a recessed shape in a bag film, and the resulting bag for a secondary battery. Background Technology

[0004] Generally speaking, in contrast to primary batteries which cannot be recharged, secondary batteries refer to rechargeable batteries, and they are widely used in high-tech electronic devices including telephones, laptops, and camcorders.

[0005] Secondary batteries are classified into can-type secondary batteries in which the electrode assembly is contained in a metal can and bag-type secondary batteries in which the electrode assembly is contained in a bag.

[0006] The pouch-type secondary battery includes an electrode assembly and a pouch for housing the electrode assembly. The electrode assembly has a structure in which positive and negative electrodes are arranged alternately and a separator is inserted between the positive and negative electrodes. The pouch includes an electrode assembly housing portion for housing the electrode assembly and a sealing portion for sealing the electrode assembly housing portion.

[0007] Here, the method for manufacturing the bag includes a process of preparing a pair of bag films, a process of forming an electrode assembly receiving portion corresponding to the pair of bag films, and a process of sealing the aligned edges of the pair of bag films.

[0008] However, this bag manufacturing method has the problem of cracking at the corners of the electrode assembly housing portion during bag film formation.

[0009] [Related Technical Documents] Patent Publication No. 2023-0016581 Summary of the Invention

[0010] Technical issues

[0011] This disclosure aims to provide a bag forming apparatus and method for increasing the moisture content of a bag film to increase its elongation, thereby preventing the bag film from breaking during forming.

[0012] This disclosure also aims to provide a bag for a secondary battery manufactured by a bag forming apparatus or method.

[0013] Technical solution

[0014] A bag forming apparatus according to embodiments of the present disclosure may include: a bag forming unit configured to form a receiving portion having a recessed shape in a bag film; and a water vapor injection unit configured to inject water vapor toward the bag film to increase the water content of a resin layer included in the bag film.

[0015] The bag forming unit may include: a mold having a forming recess in its upper surface, on which the bag film is placed; and a punch disposed above the mold and configured to form the receiving portion in the bag film when the punch is inserted into the forming recess. The water vapor injection unit may include a main injection unit for injecting water vapor toward the bag film placed on the mold.

[0016] The steam injection unit can inject steam at a temperature lower than room temperature.

[0017] The water vapor jetting unit may include an ultrasonic jetter that uses ultrasound to break down water particles to generate water vapor and then jets the water vapor.

[0018] The bag film may include an insulating layer, a resin layer, a metal layer, and a protective layer arranged sequentially. The main injection unit may include: a first main injector for injecting water vapor toward the insulating layer located on the outermost side of the bag film; and a second main injector for injecting water vapor toward the side of the bag film.

[0019] The steam injection unit can inject steam for 30 seconds to 2 minutes.

[0020] The shaped recess may have a discharge hole for discharging water droplets formed by the condensation of water vapor to the outside.

[0021] The discharge hole can be formed at the corner of the molded recess.

[0022] The bag forming equipment may further include a drying unit for drying the bag film after the containment portion is formed in the bag film to remove moisture contained in the resin layer.

[0023] The bag forming equipment may further include a conveying unit for conveying the bag film to place it on the upper surface of the mold. The water vapor injection unit may further include an auxiliary injection unit for injecting water vapor into the bag film conveyed by the conveying unit.

[0024] A bag forming method according to embodiments of the present disclosure may include: a spraying step, wherein water vapor is sprayed toward a bag film to increase the water content of a resin layer included in the bag film; and a forming step, wherein a receiving portion having a recessed shape is formed in the bag film.

[0025] The spraying step may include spraying water vapor at a temperature below room temperature.

[0026] The bag film may include an insulating layer, a resin layer, a metal layer, and a protective layer arranged sequentially. The spraying step may include spraying water vapor onto each of the outermost insulating layer and the side surface of the bag film.

[0027] The bag forming method may further include a placement step prior to the spraying step, wherein the placement step places the bag film on the upper surface of the mold having a forming recess. The spraying step may include a main spraying process that sprays water vapor onto the bag film placed on the upper surface of the mold.

[0028] The bag forming method may further include a conveying step prior to the placement step, wherein the conveying step transports the bag film toward the mold. The spraying step may further include an auxiliary spraying process, wherein water vapor is sprayed onto the bag film during the conveying step.

[0029] The molding step may include a discharge process in which water droplets formed by the condensation of water vapor and remaining in the molding recess are discharged.

[0030] The bag forming method may further include a drying step after the forming step, wherein the drying step dries the bag film to remove moisture contained in the resin layer.

[0031] A bag for a secondary battery according to embodiments of the present disclosure may include a receiving portion having a recessed shape. The bag for the secondary battery may include: an outermost insulating layer; an innermost protective layer; a metal layer located between the insulating layer and the protective layer; and a resin layer located between the insulating layer and the metal layer. The water content of the resin layer may be from 700 ppm to 2000 ppm.

[0032] The water content of the resin layer can be from 1000ppm to 1500ppm.

[0033] The thickness of the insulating layer can be from 8 μm to 15 μm.

[0034] Beneficial effects

[0035] According to an exemplary embodiment of this disclosure, the steam injection unit of the bag forming apparatus can inject steam toward the bag film to increase the moisture content of the resin layer included in the bag film. Therefore, the elongation of the bag film can be increased, thereby preventing rupture during bag film formation.

[0036] Additionally, the steam injection unit may include a main injection unit for injecting steam toward the bag film placed on the mold. Therefore, the moisture content of the bag film can be steadily increased.

[0037] In addition, the main injection unit may include a first main injector and a second main injector. The first main injector is used to inject water vapor toward the outermost insulating layer, and the second main injector is used to inject water vapor toward the side of the bag film. Therefore, the moisture content of the resin layer can be stably increased.

[0038] In addition, the steam injection unit can inject steam at a temperature lower than room temperature. Therefore, deformation of the bag film caused by steam can be prevented.

[0039] In addition, the forming recess of the mold in the bag forming equipment can have a discharge hole for discharging water droplets formed by the condensation of water vapor to the outside. Therefore, a containment portion can be stably formed in the bag film.

[0040] Furthermore, the drying unit of the bag forming equipment can dry the bag film with the receiving portion to remove moisture contained in the resin layer. Therefore, defects can be prevented during the subsequent bag sealing process. Attached Figure Description

[0041] The accompanying drawings illustrate exemplary embodiments of the present disclosure and are intended to provide a better understanding of the technical aspects of the present disclosure together with the following detailed description; therefore, the present disclosure should not be construed as being limited to the drawings.

[0042] Figure 1 is a perspective view showing a secondary battery including a bag according to an embodiment of the present disclosure.

[0043] Figure 2 is a cross-sectional view showing a bag according to an embodiment of the present disclosure.

[0044] Figure 3 is an enlarged view of part A in Figure 2.

[0045] Figure 4 is a schematic diagram illustrating the process of a bag forming apparatus according to an embodiment of the present disclosure.

[0046] Figure 5 is a perspective view of the main jetting unit of a bag forming apparatus according to an embodiment of the present disclosure.

[0047] Figure 6 is a cross-sectional view showing the discharge hole in a bag forming apparatus according to an embodiment of the present disclosure.

[0048] Figure 7 is a process diagram illustrating the auxiliary jetting unit of a bag forming apparatus according to an embodiment of the present disclosure.

[0049] Figure 8 is a flowchart illustrating a bag forming method according to an embodiment of the present disclosure. Detailed Implementation

[0050] In the following description, embodiments of the present disclosure will be described in sufficient detail with reference to the accompanying drawings to enable those skilled in the art to readily perform the disclosure. However, the present disclosure may be implemented in many different forms and is not limited to the disclosed embodiments. Furthermore, in the drawings, some elements unrelated to the description have been omitted for clarity, and similar reference numerals are attached to similar elements throughout the specification.

[0051] FIG1 is a perspective view showing a secondary battery including a bag according to an embodiment of the present disclosure, FIG2 is a cross-sectional view showing a bag according to an embodiment of the present disclosure, and FIG3 is an enlarged view of part A in FIG2.

[0052] As shown in Figures 1 to 3, the secondary battery 1 may include an electrode assembly 11 and a bag 12 for accommodating the electrode assembly 11.

[0053] The electrode assembly 11 may have a structure in which multiple electrodes and multiple diaphragms are arranged in an alternating manner. The multiple electrodes may include positive and negative electrodes.

[0054] The bag 12 according to an embodiment of the present disclosure is used for a secondary battery. The bag 12 may be configured to accommodate an electrode assembly 11 and includes a pair of bag films 13. The pair of bag films 13 may include a receiving portion 131 for accommodating the electrode assembly 11 and a sealing portion 132 located at the edge of the receiving portion 131.

[0055] In other words, the receiving portion 131 formed in one bag film 13 and the receiving portion 131 formed in another bag film 13 can form a receiving space for receiving the electrode assembly 11. The receiving space can be sealed by heating to join the sealing portion 132 formed in one bag film 13 and the sealing portion 132 formed in another bag film 13 together.

[0056] However, this disclosure is not limited thereto, and in the pair of pouch films 13, only one pouch film 13 may have a receiving portion 131. In this case, the other pouch film 13 may be flat. Such an example is referred to as a single-cup structure, and such an example will be readily understood by those skilled in the art.

[0057] As shown in Figure 3, the bag film 13 may include an insulating layer 1311, a resin layer 1312, a metal layer 1313, and a protective layer 1314 arranged sequentially. That is, the insulating layer 1311 may be disposed on the outermost side of the bag film 13, and the protective layer 1314 may be disposed on the innermost side. Furthermore, the metal layer 1313 may be located between the insulating layer 1311 and the protective layer 1314. Additionally, the resin layer 1312 may be located between the insulating layer 1311 and the metal layer 1313.

[0058] The insulating layer 1311 may include a moisture-permeable material. For example, the insulating layer 1311 may include polyethylene terephthalate.

[0059] The resin layer 1312 may include a material capable of readily absorbing moisture. For example, the resin layer 1312 may include nylon.

[0060] Metal layer 1313 may include aluminum. Protective layer 1314 may include polypropylene.

[0061] However, this disclosure is not limited thereto, and those skilled in the art can appropriately select the material of each layer of the bag film 13 within the known scope.

[0062] Alternatively, the bag 12 can be manufactured by forming receiving portions 131 for accommodating the electrode assembly 11 in a pair of bag films 13. In this case, the bag forming apparatus 2 according to an embodiment of the present disclosure can be used.

[0063] Specifically, the bag forming equipment 2 can increase the elongation of the bag film 13, thereby preventing rupture when the receiving portion 131 is formed in the bag film 13.

[0064] In the following, a bag forming apparatus according to an embodiment of the present disclosure will be described in detail with reference to the accompanying drawings.

[0065] Figure 4 is a schematic diagram illustrating the process of a bag forming apparatus according to an embodiment of the present disclosure, and Figure 5 is a perspective view of the main injection unit of the bag forming apparatus according to an embodiment of the present disclosure.

[0066] As shown in Figures 4 and 5, the bag forming apparatus 2 according to an embodiment of the present disclosure may include: a bag forming unit 21 for forming a receiving portion 131 with a concave shape in the bag film 13; and a water vapor injection unit 22 for injecting water vapor toward the bag film 13 to increase the moisture content of the resin layer 1312 included in the bag film 13.

[0067] The bag forming unit 21 is configured to form a receiving portion 131 with a recessed shape in the bag film 13.

[0068] That is, the bag forming unit 21 may include: a mold 211 having a forming recess 2111 located in an upper surface on which the bag film 13 is placed; and a punch 212 disposed above the mold 211 and configured to form a receiving portion 131 in the bag film 13 when inserted into the forming recess 2111.

[0069] At least a portion of the punch 212 can be inserted into the forming recess 2111, thereby applying pressure to the bag film 13 and thus forming a receiving portion 131 in the bag film 13.

[0070] The water vapor injection unit 22 is used to increase the elongation of the bag film 13 using water vapor. The water vapor injection unit 22 can be configured to inject water vapor. Here, water vapor includes liquid water and gaseous water that can be injected.

[0071] In other words, the water vapor injection unit 22 can inject water vapor toward the bag film 13 to increase the water content of the resin layer 1312 included in the bag film 13, thereby increasing the elongation of the bag film 13.

[0072] The water vapor injection unit 22 may include a main injection unit 221, which is used to inject water vapor toward the bag film 13 placed on the upper surface of the mold 211 before forming the bag film 13.

[0073] More specifically, the main injection unit 221 may include a first main injector 2211 that injects water vapor toward the insulating layer 1311 and a second main injector 2212 that injects water vapor toward the side of the bag membrane 13.

[0074] When the first main injector 2211 sprays water vapor toward the insulating layer 1311 of the bag film 13, some water vapor can pass through the insulating layer 1311 and enter the resin layer 1312, thus increasing the water content of the resin layer 1312.

[0075] When the second main injector 2212 sprays water vapor toward the side of the bag film 13, some water vapor can be absorbed into the resin layer 1312 exposed to the side of the bag film 13, thus increasing the water content of the resin layer 1312.

[0076] Specifically, the main spraying unit 221 can spray water vapor for a preset time, so that the entire resin layer 1312 included in the bag film 13 can have a set moisture absorption capacity. The preset time can be from 30 seconds to 10 minutes. For example, the preset time can be about 2 minutes. If the preset time is 30 seconds or less, the absorption of moisture into the bag film 13 may be insufficient, and if the preset time is 10 minutes or more, the molding process time may be excessively increased.

[0077] The resin layer 1312 of the bag film 13 may include nylon. Due to its high tensile strength, abrasion resistance, elasticity, and moisture absorption, nylon is suitable as a material for the resin layer 1312.

[0078] The insulating layer 1311 of the bag film 13 can have a thickness from 8 μm to 15 μm to increase water vapor permeability. For example, the thickness of the insulating layer 1311 can be approximately 12 μm. When the thickness of the insulating layer 1311 is 8 μm or less, the insulating layer 1311 may be easily damaged due to contact with the external environment. When the thickness of the insulating layer 1311 is 15 μm or more, it is difficult to increase the water content of the resin layer 1312 due to the low water vapor permeability.

[0079] The resin layer 1312 of the bag film 13 can have a thickness from 20 μm to 30 μm. For example, the thickness of the resin layer 1312 can be about 25 μm.

[0080] The metal layer 1313 of the bag membrane 13 can have a thickness from 45 μm to 75 μm. For example, the thickness of the metal layer 1313 can be approximately 60 μm.

[0081] The protective layer 1314 of the bag film 13 can have a thickness from 60 μm to 100 μm. For example, the thickness of the protective layer 1314 can be approximately 80 μm.

[0082] Those skilled in the art will understand that the thickness range of each layer of the bag film 13 can also be applied to the bag 12 according to embodiments of the present disclosure.

[0083] In addition, the steam injection unit 22 can inject steam at a temperature of 100°C or lower. Preferably, the steam injection unit 22 can inject steam at a temperature below room temperature. Therefore, the bag membrane 13 can be prevented from being damaged or deformed by steam.

[0084] For example, the water vapor injection unit 22 may include an ultrasonic ejector that uses ultrasound to break down water particles to generate water vapor and eject the water vapor.

[0085] The steam injection unit 22 can increase the elongation of the bag film 13 by increasing the water content of the resin layer 1312 included in the bag film 13. When the elongation of the resin layer 1312 increases, the elongation of the bag film 13 increases, thereby preventing rupture during the molding of the bag film 13. In other words, it can prevent the metal layer 1313 from being exposed to the external environment due to rupture.

[0086] More specifically, the moisture content of the resin layer 1312 of the bag film 13 can be from 700 ppm to 2000 ppm. Preferably, the moisture content of the resin layer 1312 can be from 1000 ppm to 1500 ppm.

[0087] When the moisture content of the resin layer 1312 is below 700 ppm, the effect of increasing the elongation of the bag film 13 may not be significant. In addition, given the effect of increasing the elongation of the bag film 13, in order to increase the moisture content of the resin layer 1312 to above 2000 ppm, the amount of water vapor sprayed onto the bag film 13 or the spraying time may need to be increased unnecessarily.

[0088] Those skilled in the art will understand that the moisture content of the resin layer 1312 of the bag film 13 can also be applied to the bag 12 according to embodiments of the present disclosure.

[0089] Furthermore, if water droplets formed by the condensation of sprayed water vapor remain in the forming recess 2111 of the mold 211, the receiving portion 131 may not be accurately formed in the bag film 13. To solve this problem, a discharge hole 2112 can be formed in the forming recess 2111 to discharge the water droplets formed by the condensation of water vapor to the outside.

[0090] Figure 6 is a cross-sectional view showing the discharge hole in a bag forming apparatus according to an embodiment of the present disclosure.

[0091] The discharge hole 2112 can be formed in the forming recess 2111 of the mold 211 to discharge water droplets formed by the condensation of water vapor to the outside.

[0092] A drain hole 2112 can be formed at the corner of the molding recess 2111. The drain hole 2112 can slide downward from the bottom surface of the molding recess 2111 toward the lower surface of the mold 211. Therefore, water droplets remaining in the molding recess 2111 can be effectively removed.

[0093] Additionally, the bag forming equipment 2 may also include a drying unit 23 for drying the bag film 13 having a receiving portion 131.

[0094] The drying unit 23 can evaporate and remove moisture contained in the resin layer 1312 by raising the temperature of the bag film 13 having the receiving portion 131. Therefore, when the bag film 13 is bonded together by heating in a subsequent process of manufacturing the bag 12, the sealability of the bag film 13 can be prevented from decreasing due to moisture.

[0095] Figure 7 is a process diagram illustrating the auxiliary jetting unit of a bag forming apparatus according to an embodiment of the present disclosure.

[0096] Additionally, the bag forming apparatus 2 may also include a conveying unit 213 for conveying the bag film 13 to place the bag film 13 on the upper surface of the mold 211. For example, the conveying unit 213 may include a conveyor belt. However, the configuration of the conveying unit 213 is not limited thereto.

[0097] The water vapor injection unit 22 may further include an auxiliary injection unit 222 for injecting water vapor toward the bag film 13 conveyed by the conveying unit 213. The auxiliary injection unit 222 can increase the elongation by increasing the water content of the resin layer 1312 included in the bag film 13.

[0098] More specifically, the auxiliary spraying unit 222 may include a first auxiliary sprayer 2221 and a second auxiliary sprayer 2222. The first auxiliary sprayer 2221 is used to spray water vapor toward the insulating layer 1311 of the bag film 13 conveyed by the conveying unit 213, and the second auxiliary sprayer 2222 is used to spray water vapor toward the side of the bag film 13.

[0099] When the first auxiliary injector 2221 sprays water vapor toward the insulating layer 1311, some of the water vapor can pass through the insulating layer 1311 and enter the resin layer 1312, thereby increasing the water content of the resin layer 1312.

[0100] When the second auxiliary injector 2222 sprays water vapor toward the side of the bag film 13, some water vapor can enter the resin layer 1312 exposed to the side of the bag film 13, thus increasing the water content of the resin layer 1312.

[0101] Therefore, the water vapor injection unit 22 can inject water vapor toward the bag film 13 to increase the water content of the resin layer 1312 included in the bag film 13, thereby increasing the elongation of the bag and thus preventing rupture during the formation of the bag film 13.

[0102] Figure 8 is a flowchart illustrating a bag forming method according to an embodiment of the present disclosure.

[0103] The bag forming method according to embodiments of the present disclosure may include the following steps: spraying water vapor toward the bag film 13 to increase the water content of the resin layer 1312 included in the bag film 13 (S30); and forming a receiving portion 131 having a concave shape in the bag film 13 (S40).

[0104] The bag forming method may also include a placement step S20 prior to the spraying step S30, which places the bag film 13 on the upper surface of the mold 211 having a forming recess 2111.

[0105] The bag forming method may also include a conveying step S10 prior to the placement step S20, which conveys the bag film 13 toward the mold 211.

[0106] The bag forming method may also include a drying step S50 after the forming step S40, which dries the bag film 13 to remove moisture contained in the resin layer 1312.

[0107] Regarding the bag forming method, as described above, the bag film 13 may include an insulating layer 1311, a resin layer 1312, a metal layer 1313, and a protective layer 1314 arranged sequentially.

[0108] Each step will be described in further detail below.

[0109] In the conveying step S10, the bag film 13 can be conveyed to the mold 211 using the conveying unit 213.

[0110] In placement step S20, the bag film 13 conveyed in conveying step S10 can be placed on the upper surface of mold 211. For example, the bag film 13 can be placed on the upper surface of mold 211 after the bag film 13 is aspirated using a moving device (not shown) such as a suction device. As described above, mold 211 may have a forming recess 2111 in its upper surface.

[0111] The spraying step S30 can be a step of increasing the elongation of the bag film 13 by spraying water vapor onto the bag film 13 to increase the moisture content of the resin layer 1312. The spraying step S30 can be performed by the water vapor spraying unit 22.

[0112] The spraying step S30 may include a main spraying process that sprays water vapor toward the bag film 13 placed on the upper surface of the mold 211. The main spraying process may be performed by the main spraying unit 221.

[0113] The spraying step S30 may also include an auxiliary spraying process in which water vapor is sprayed toward the bag film 13 during the conveying of the bag film 13 in the conveying step S10. The auxiliary spraying process may be performed by the auxiliary spraying unit 222.

[0114] In the spraying step S30, water vapor can be sprayed toward each of the outermost insulating layer 1311 and the side surface of the bag film 13. When water vapor is sprayed toward the insulating layer 1311, some water vapor can pass through the insulating layer 1311 and enter the resin layer 1312, thus increasing the water content of the resin layer 1312. Additionally, when water vapor is sprayed toward the side surface of the bag film 13, some water vapor can enter the resin layer 1312 exposed to the side surface of the bag film 13, thus increasing the water content of the resin layer 1312.

[0115] More specifically, during the main spraying process, for the bag film 13 placed on the upper surface of the mold 211, the first main sprayer 2211 can spray water vapor toward the insulating layer 1311 of the bag film 13, and the second main sprayer 2212 can spray water vapor toward the side of the bag film 13.

[0116] More specifically, during the auxiliary spraying process, for the bag film 13 conveyed in the conveying step S10, the first auxiliary sprayer 2221 can spray water vapor toward the insulating layer 1311 of the bag film 13, and the second auxiliary sprayer 2222 can spray water vapor toward the side of the bag film 13.

[0117] Additionally, in the spraying step S30, water vapor with a temperature below 100°C can be sprayed, preferably water vapor with a temperature below room temperature. This is to prevent deformation of the bag membrane 13 caused by water vapor.

[0118] In the forming step S40, the punch 212 can form a receiving portion 131 in the bag film 13 placed on the mold 211. More specifically, in the forming step S40, the punch 212 can move downward and insert into the forming recess 2111 of the mold 211, thereby applying pressure to the bag film 13. Thus, a portion of the bag film 13 can be inserted into the forming recess 2111 together with the punch 212 to form the receiving portion 131 in the bag film 13.

[0119] The molding step S40 may include a drainage process for draining water droplets remaining in the molding recess 2111 before forming the bag film 13. During the drainage process, water droplets formed by water vapor condensation and remaining in the molding recess 2111 may be drained to the outside through drainage holes 2112 formed at the corners of the molding recess 2111.

[0120] After molding step S40, drying step S50 may include drying the bag film 13 having receiving portion 131 to remove moisture contained in resin layer 1312.

[0121] For example, in the drying step S50, a heating device such as a heater can be used to increase the temperature of the bag film 13 having the receiving portion 131. Therefore, moisture contained in the resin layer 1312 of the bag film 13 can be evaporated and removed. Thus, when the bag films 13 are bonded together by heating in subsequent processes of bag 12 manufacturing, the sealing performance of the bag films 13 can be prevented from decreasing due to moisture.

[0122] Therefore, the bag forming method according to the embodiments of the present disclosure can significantly reduce the defect rate of the bag 12 and produce a high-quality bag film 13.

[0123] The following section describes the experiments used to study elongation and formability as a function of the moisture content of the bag film 13.

[0124] Here, the bag film (hereinafter referred to as the test object) includes an insulating layer 1311, a resin layer 1312, a metal layer 1313, and a protective layer 1314 arranged in the order of insulating layer 1311, resin layer 1312, metal layer 1313, and protective layer 1314.

[0125] The insulating layer 1311 of the experimental material is made of polyethylene terephthalate, the resin layer 1312 is made of nylon, the metal layer 1313 is made of aluminum, and the protective layer 1314 is made of polypropylene. Furthermore, the thickness of the insulating layer 1311 is 12 μm, the resin layer 1312 is 25 μm, the metal layer 1313 is 60 μm, and the protective layer 1314 is 80 μm.

[0126] The first experimental condition was to place the five experimental subjects in a dry room without moisture for one day, and then measure the moisture content (ppm).

[0127] The second experimental condition was to place the five experimental subjects in a laboratory at room temperature (20°C to 30°C) for one day, and then measure the water content (ppm).

[0128] The third experimental condition was to place the five experimental subjects at 60°C. o In a laboratory at 90% humidity and at a temperature of 1°C, the water content (ppm) was measured for 10 minutes.

[0129] The fourth experimental condition was to place the five experimental subjects in a 60°C environment. o The sample was placed in a laboratory at 90% humidity for one day, and then the moisture content (ppm) was measured.

[0130] Here, a commonly used moisture meter is used to measure the moisture content of the experimental subjects subjected to the first through fourth experimental conditions. For example, the MOICO-A19 from Rigong International can be used. Additionally, the elongation is measured by pulling on both ends of the experimental subjects subjected to the first through fourth experimental conditions.

[0131] The five experimental subjects used were identical and were indicated by numbers 1 to 5.

[0132] The results of measuring the water content and elongation of the experimental subjects that underwent the first to fourth experimental conditions are shown in Table 1 below.

[0133] [Table 1]

[0134] Referring to Table 1 above, it is confirmed that under the conditions of the third and fourth experiments, 60 o In a laboratory with a humidity level of 90% and a temperature of C, the moisture content of the experimental subjects increased significantly. It can be seen that when water vapor is sprayed onto the bag film according to this disclosure, the moisture content of the bag film increases.

[0135] Furthermore, it was confirmed that the elongation of the test subjects subjected to the third and fourth experimental conditions increased. It can be seen that when water vapor is sprayed onto the bag film to increase the moisture content, the elongation also increases. In other words, as the elongation of the bag film increases, it is possible to prevent the bag film from rupturing during molding.

[0136] The scope of this disclosure is defined by the appended claims rather than the detailed description, and various modifications and variations can be made to the implementation from the meaning and scope of protection and their equivalent concepts.

[0137] [List of reference numerals]

[0138] 1: Secondary battery; 11: Electrode assembly

[0139] 12: Bag 13: Bag film

[0140] 131: Receiving part; 1311: Insulating layer

[0141] 1312: Resin layer; 1313: Metal layer

[0142] 1314: Protective layer; 132: Sealing part

[0143] 2: Bag forming equipment 21: Bag forming unit

[0144] 211: Mold 2111: Molding concave portion

[0145] 2112: Discharge hole; 212: Punch

[0146] 213: Conveying unit; 22: Water vapor injection unit

[0147] 221: Main injection unit; 2211: First main injector

[0148] 2212: Second main injector; 222: Auxiliary injection unit

[0149] 2221: First auxiliary injector; 2222: Second auxiliary injector

[0150] 23: Drying Unit

Claims

1. A bag forming device, the bag forming device comprising: A bag forming unit configured to form a receiving portion with a recessed shape in a bag film; And a water vapor injection unit configured to inject water vapor toward the bag film to increase the water content of the resin layer included in the bag film.

2. The bag forming equipment according to claim 1, wherein, The bag forming unit includes: a mold having a forming recess in an upper surface for placing the bag film; and a punch disposed above the mold and configured to form the receiving portion in the bag film when the punch is inserted into the forming recess, wherein the water vapor injection unit includes a main injection unit for injecting water vapor toward the bag film placed on the mold.

3. The bag forming equipment according to claim 1, wherein, The steam injection unit injects steam at a temperature lower than room temperature.

4. The bag forming equipment according to claim 1, wherein, The water vapor injection unit includes an ultrasonic jetter that uses ultrasound to decompose water particles to generate water vapor and then ejects the water vapor.

5. The bag forming equipment according to claim 2, wherein, The bag film includes an insulating layer, a resin layer, a metal layer, and a protective layer arranged in sequence, and wherein the main spraying unit includes: a first main sprayer for spraying water vapor toward the insulating layer located on the outermost side of the bag film; and a second main sprayer for spraying water vapor toward the side of the bag film.

6. The bag forming equipment according to claim 1, wherein, The steam injection unit injects steam for 30 seconds to 2 minutes.

7. The bag forming equipment according to claim 2, wherein, The molded recess has a discharge hole for discharging water droplets formed by the condensation of water vapor to the outside.

8. The bag forming equipment according to claim 7, wherein, The discharge hole is formed at the corner of the molded recess.

9. The bag forming equipment according to claim 1, wherein the bag forming equipment further comprises: A drying unit is used to dry the bag film after the receiving portion is formed in the bag film to remove moisture contained in the resin layer.

10. The bag forming equipment according to claim 2, wherein the bag forming equipment further comprises: The conveying unit is used to convey the bag film to place the bag film on the upper surface of the mold, wherein the water vapor injection unit further includes an auxiliary injection unit for injecting water vapor into the bag film conveyed by the conveying unit.

11. A bag forming method, the bag forming method comprising: The spraying step involves spraying water vapor toward the bag film to increase the water content of the resin layer included in the bag film. And a molding step, wherein the molding step forms a receiving portion having a recessed shape in the bag film.

12. The bag forming method according to claim 11, wherein, The spraying step includes spraying water vapor at a temperature below room temperature.

13. The bag forming method according to claim 11, wherein, The bag film includes an insulating layer, a resin layer, a metal layer, and a protective layer arranged in sequence, and wherein the spraying step includes spraying water vapor onto each of the insulating layer located on the outermost side of the bag film and the side surface of the bag film.

14. The bag forming method according to claim 11, wherein the bag forming method further comprises, prior to the spraying step: The placement step involves placing the bag film on the upper surface of the mold having a forming recess, wherein the spraying step includes a main spraying process that sprays water vapor onto the bag film placed on the upper surface of the mold.

15. The bag forming method according to claim 14, wherein the bag forming method further comprises, prior to the placement step: The conveying step, wherein the conveying step conveys the bag film toward the mold, wherein the spraying step further includes: an auxiliary spraying process, wherein the auxiliary spraying process sprays water vapor onto the bag film while the bag film is conveyed in the conveying step.

16. The bag forming method according to claim 14, wherein, The molding step includes a discharge process, in which water droplets formed by the condensation of water vapor and remaining in the molding recess are discharged.

17. The bag forming method according to claim 11, wherein the bag forming method further comprises, after the forming step: A drying step, wherein the bag film is dried to remove moisture contained in the resin layer.

18. A bag for a secondary battery, the bag having a recessed receiving portion, the bag for the secondary battery comprising: An insulating layer, wherein the insulating layer is located on the outermost side; A protective layer, which is located on the innermost side; A metal layer, wherein the metal layer is located between the insulating layer and the protective layer; And a resin layer located between the insulating layer and the metal layer, wherein the water content of the resin layer is 700 ppm to 2000 ppm.

19. The bag for a secondary battery according to claim 18, wherein, The water content of the resin layer is between 1000 ppm and 1500 ppm.

20. The bag for a secondary battery according to claim 18, wherein, The thickness of the insulating layer is 8 μm to 15 μm.

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