Pouch-type battery case and manufacturing method thereof, and manufacturing method of secondary battery

Abstract

A pouch-type battery case according to an embodiment of the present invention may include a cup portion having an indented shape and a gas pocket portion having an indented shape located on one side of the cup portion. A peripheral portion of the gas pocket portion may have wrinkles formed thereon that fold and expand to vary the depth of the gas pocket portion depending on the internal pressure of the gas pocket portion. The wrinkles may include protrusions that protrude outward from the gas pocket portion and recesses that are alternately positioned with the protrusions in the depth direction of the gas pocket portion. The remaining thickness of the protrusions may be thinner than the remaining thickness of the recesses.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0108708, filed on August 29, 2022, and all contents disclosed in the documents of that Korean patent application are incorporated herein by reference.

[0002] The present invention relates to a pouch-type battery case, a method for manufacturing the same, and a method for manufacturing a secondary battery using the pouch-type battery case. [Background technology]

[0003] In general, secondary batteries are batteries that can be charged and discharged, unlike primary batteries that cannot be recharged, and are widely used in electronic devices such as mobile phones, laptops, and camcorders, as well as electric vehicles, etc. In particular, lithium secondary batteries have a larger capacity than nickel-cadmium batteries or nickel-metal hydride batteries and a higher energy density per unit weight, so their use is rapidly increasing.

[0004] Secondary batteries can be classified by the type of battery case, and representative examples include can-type secondary batteries including cylindrical battery cases and prismatic battery cases, and pouch-type secondary batteries including pouch-type battery cases.

[0005] The pouch-type battery case may include a cup portion for accommodating the electrode assembly and a gas pocket portion for collecting gas. The gas pocket portion may be formed by drawing using a forming device, similar to the cup portion for accommodating the electrode assembly.

[0006] In more detail, the method for manufacturing a pouch-type secondary battery may include sealing a portion of the pouch-type battery case with the electrode assembly housed in the cup portion, injecting an electrolyte solution through an unsealed opening of the pouch-type battery case, sealing the opening, and activating the electrode assembly by charging and discharging. In addition, gas generated during the activation step may be collected in a gas pocket portion.

[0007] On the other hand, in order to prevent unnecessary gas or air from remaining inside the pouch-type battery case, the step of sealing the opening is generally carried out in a negative pressure chamber (for example, a vacuum chamber).

[0008] However, unlike the cup portion in which the electrode assembly is housed, the gas pocket portion may not maintain its shape due to the negative pressure, and may be distorted or deformed. When the gas pocket portion is distorted or deformed, the volume of the gas pocket portion decreases, resulting in an insufficient gas collection, and therefore, an improvement is required. Summary of the Invention [Problem to be solved by the invention]

[0009] One problem that the present invention aims to solve is to provide a pouch-type battery case and a manufacturing method thereof that can prevent distortion of the gas pocket portion by wrinkles formed in the gas pocket portion and can capture a sufficiently large amount of gas.

[0010] Another object of the present invention is to provide a method for manufacturing a secondary battery including the pouch-type battery case. [Means for solving the problem]

[0011] A pouch-type battery case according to an embodiment of the present invention may include a cup portion having an indented shape and a gas pocket portion having an indented shape located on one side of the cup portion. A peripheral portion of the gas pocket portion may have wrinkles formed thereon that fold and expand to vary the depth of the gas pocket portion depending on the internal pressure of the gas pocket portion. The wrinkles may include protrusions that protrude outward from the gas pocket portion and recesses that are alternately positioned with the protrusions in the depth direction of the gas pocket portion. The remaining thickness of the protrusions may be thinner than the remaining thickness of the recesses.

[0012] The depth of the gas pocket portion may be variable between a contracted depth and an expanded depth that is deeper than the contracted depth, and the expanded depth may be 0.7 to 1.3 times the depth of the cup portion.

[0013] The depth of the gas pocket may be variable between a contracted depth and an expanded depth that is deeper than the contracted depth, and the expanded depth may be 12 times or more the contracted depth.

[0014] A method for manufacturing a pouch-type battery case according to an embodiment of the present invention may include forming a cup portion and a gas pocket portion in a pouch sheet, and forming a wrinkled portion around the periphery of the gas pocket portion that folds and expands to vary the depth of the gas pocket depending on the internal pressure of the gas pocket. The wrinkled portion may include convex portions that protrude outward from the gas pocket portion and concave portions that are alternately positioned with the convex portions in a depth direction of the gas pocket. The remaining thickness of the convex portions may be thinner than the remaining thickness of the concave portions.

[0015] The gas pocket portion in which the wrinkle portion is formed may have an initial depth, and the depth of the gas pocket portion may be variable between a contracted depth smaller than the initial depth and an expanded depth larger than the initial depth.

[0016] The contracted depth may be 0.1 times or less the initial depth.

[0017] The expanded depth may be 1.2 to 1.3 times the initial depth.

[0018] The device for forming the wrinkled portion may include a plurality of support portions that are in contact with the outer peripheral edge of the gas pocket portion and are arranged at predetermined intervals in the depth direction of the gas pocket portion, and a negative pressure portion that applies negative pressure to the outer peripheral edge of the gas pocket portion through the intervals between the plurality of support portions.

[0019] A method for manufacturing a secondary battery according to an embodiment of the present invention may include the steps of preparing a pouch-type battery case, accommodating an electrode assembly and an electrolyte in a cup portion of the pouch-type battery case, sealing the pouch-type battery case in a negative pressure chamber, and collecting gas generated by charging and discharging the electrode assembly in a gas pocket portion of the pouch-type battery case. The step of preparing the pouch-type battery case may include the steps of forming the cup portion and the gas pocket portion in a pouch sheet, and forming a wrinkled portion around the periphery of the gas pocket portion that folds and expands depending on the internal pressure of the gas pocket portion so that the depth of the gas pocket portion can be varied. The wrinkled portion may include a convex portion protruding outward from the gas pocket portion and a concave portion alternately positioned with the convex portion in the depth direction of the gas pocket portion. The remaining thickness of the convex portion may be thinner than the remaining thickness of the concave portion.

[0020] In the step of preparing the pouch-type battery case, the gas pocket portion may be formed to an initial depth, and in the step of sealing the pouch-type battery case, the depth of the gas pocket portion may change to a contracted depth that is smaller than the initial depth.

[0021] In the step of collecting the gas in the gas pocket, the depth of the gas pocket may be changed to an expanded depth that is greater than the initial depth. [Effects of the Invention]

[0022] According to a preferred embodiment of the present invention, even if negative pressure acts inside the gas pocket when sealing the pouch-type battery case, the wrinkled portion contracts and the depth of the gas pocket decreases, thereby preventing distortion of the gas pocket.

[0023] Furthermore, when gas is trapped in the gas pocket, the internal pressure of the gas pocket increases, expanding the wrinkles and increasing the depth of the gas pocket, allowing the gas pocket to stably trap a sufficiently large amount of gas.

[0024] Other effects may be included that can be easily predicted by a person skilled in the art from the configuration according to the preferred embodiment of the present invention. [Brief explanation of the drawings]

[0025] The following drawings attached to this specification illustrate preferred embodiments of the present invention and, together with the detailed description of the invention described below, serve to further understand the technical concept of the present invention. Therefore, the present invention should not be interpreted as being limited solely to the matters depicted in such drawings.

[0026] [Figure 1] 1 is an assembly diagram showing a pouch-type battery case and an electrode assembly housed therein according to an embodiment of the present invention. [Figure 2] 10 is a perspective view of a pouch-type battery case according to an embodiment of the present invention, seen from another direction. FIG. [Figure 3] FIG. 2 is a side view of a pouch-type battery case according to one embodiment of the present invention. [Figure 4] FIG. 4 is a diagram showing a state in which the gas pocket portion shown in FIG. 3 is contracted. [Figure 5] FIG. 4 is a diagram showing a state in which the gas pocket portion shown in FIG. 3 is expanded. [Figure 6] 1 is a schematic diagram of an apparatus for forming wrinkles according to an embodiment of the present invention. [Figure 7] 10 is a flowchart of a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8a] 5A to 5C are schematic diagrams sequentially illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8b] 5A to 5C are schematic diagrams sequentially illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8c] 5A to 5C are schematic diagrams sequentially illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8d] 5A to 5C are schematic diagrams sequentially illustrating a method for manufacturing a secondary battery according to another embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] The present invention will be described in detail below with reference to the accompanying drawings, so that those skilled in the art can easily understand the preferred embodiments of the present invention. However, the present invention can be realized in various different forms and is not limited to the following embodiments.

[0028] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention will be omitted, and when assigning reference symbols to components in each drawing in this specification, the same or similar reference symbols will be assigned to the same or similar components throughout the specification.

[0029] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that an inventor can appropriately define the concept of a term in order to best explain his or her invention.

[0030] FIG. 1 is an assembly diagram showing a pouch-type battery case and an electrode assembly housed therein according to one embodiment of the present invention.

[0031] A pouch-shaped battery case 100 (hereinafter referred to as "battery case") according to one embodiment of the present invention can be manufactured by molding a pouch sheet 137. The pouch sheet 137 may be a sheet-like member formed by laminating multiple layers. For example, the pouch sheet 137 may include a first resin layer (e.g., polypropylene) forming one side, a second resin layer (e.g., polyethylene terephthalate) forming the other side, and a metal layer (e.g., aluminum) positioned between the first and second resin layers. The pouch sheet 137 may be flexible and moldable.

[0032] The battery case 100 may include a cup portion 110 having a concave shape and a gas pocket portion 120 having a concave shape and located on one side of the cup portion 110. The battery case 100 may further include terraces 130 located on the peripheries of the cup portion 110 and the gas pocket portion 120.

[0033] More specifically, the battery case 100 may include a first case 101 and a second case 102. Hereinafter, a case in which the first case 101 and the second case 102 are integrally connected as shown in FIG. 1 will be described as an example. The first case 101 and the second case 102 may be separated by a folding section 140. When the folding section 140 is folded, the first case 101 and the second case 102 may face each other. However, this is not a limitation, and it goes without saying that the first case 101 and the second case 102 may be manufactured separately.

[0034] At least one of the first case 101 and the second case 102 may include a cup portion 110. Furthermore, at least one of the first case 101 and the second case 102 may include a gas pocket portion 120. Hereinafter, as shown in FIG. 1 , a case will be described as an example in which the first case 101 includes the cup portion 110 and the gas pocket portion 120, and the second case 102 does not include the cup portion 110 or the gas pocket portion 120. Those skilled in the art will easily understand an embodiment in which each of the first case 101 and the second case 102 includes the cup portion 110 and the gas pocket portion 120.

[0035] The cup portion 110 may be recessed from the terrace 130 by a predetermined depth to form a space for accommodating the electrode assembly 200. After the electrode assembly 200 is accommodated in the cup portion 110, the folding portion 140 may be folded. In this way, the second case 102 may cover the electrode assembly 200 accommodated in the cup portion 110. Thus, the electrode assembly 200 may be accommodated in the cup portion 110.

[0036] The gas pocket portion 120 may be recessed in the same direction as the cup portion 110. The gas pocket portion 120 can form a space in which gas is trapped.

[0037] The gas pocket portion 120 may be located on one side of the cup portion 110. More specifically, the gas pocket portion 120 may be located on the opposite side of the cup portion from the folding portion 140.

[0038] The periphery of the gas pocket 120 may be formed with wrinkles 121 that fold and expand so that the depth of the gas pocket 120 can be varied depending on the internal pressure of the gas pocket 120. The wrinkles 121 may have a bellows shape. More specifically, the wrinkles 121 may be formed so that convex portions 122 (see FIG. 3 ) and concave portions 123 are alternately formed in the depth direction of the gas pocket 120.

[0039] Meanwhile, the electrode assembly 200 may be formed by interposing a separator between multiple electrodes. For example, the electrode assembly 200 may be a simple stack type in which multiple electrodes and separators are alternately stacked, or a lamination & stack type in which unit cells, each of which is formed by laminating an electrode and a separator, are stacked. However, the electrode assembly 200 is not limited thereto. The electrode assembly 200 may be a jelly-roll type in which an electrode sheet and a separator sheet are wound together, a stack & folding type in which a separator sheet on which unit cells are stacked is folded, or a z-folding type in which a separator sheet on which multiple electrodes are stacked is folded in a zigzag pattern.

[0040] The electrode assembly 200 may be provided with electrode tabs 210. The electrode tabs 210 may protrude outward from the electrodes of the electrode assembly 200. More specifically, a plurality of positive electrode tabs 211 connected to a plurality of positive electrodes and a plurality of negative electrode tabs 212 connected to a plurality of negative electrodes may protrude in different directions (e.g., opposite directions) relative to the electrode assembly 200. However, this is not a limitation, and it goes without saying that the positive electrode tabs 211 and the negative electrode tabs 212 may protrude side by side.

[0041] Electrode leads 220 may be connected to the multiple electrode tabs 210. More specifically, the positive electrode lead 221 may be connected to the multiple positive electrode tabs 211, and the negative electrode lead 222 may be connected to the multiple negative electrode tabs 212.

[0042] The electrode lead 220 may have one end connected to the plurality of electrode tabs 210 and the other end protruding outside the battery case 100 .

[0043] A portion of each electrode lead 220 may be surrounded by an insulating portion 230. For example, the insulating portion 230 may include insulating tape. When the electrode assembly 200 is housed in the cup portion 110, the insulating portion 230 may be positioned to correspond to the terrace 130 of the battery case 100. When the battery case 100 is sealed, the insulating portion 230 may be heat-sealed to the terrace 130. Thus, the insulating portion 230 insulates the electrode lead 220 from the battery case 100, and can maintain the sealing of the battery case 100.

[0044] FIG. 2 is a perspective view of a pouch-type battery case according to one embodiment of the present invention, viewed from another direction; FIG. 3 is a side view of a pouch-type battery case according to one embodiment of the present invention; FIG. 4 is a view showing the gas pocket portion shown in FIG. 3 in a contracted state; and FIG. 5 is a view showing the gas pocket portion shown in FIG. 3 in an expanded state.

[0045] For convenience of explanation, the first case 101 shown in FIG. 1 is shown in FIGS.

[0046] The depth of the gas pocket 120 may be made variable by the wrinkles 121 formed in the gas pocket 120 .

[0047] As described above, the wrinkles 121 may have a bellows shape. More specifically, the wrinkles 121 may include protrusions 122 that protrude outward from the gas pocket 120 and recesses 123 that are alternately positioned with the protrusions 122 in the depth direction of the gas pocket 120.

[0048] The protrusions 122 may be formed so as to bulge outward from the gas pocket 120. The recesses 123 may be formed so as to be recessed inward from the gas pocket 120.

[0049] The remaining thickness t1 of the protrusion 122 may be thinner than the remaining thickness t2 of the recess 123. More specifically, the remaining thickness t1 of the outermost portion of the protrusion 122 may be thinner than the remaining thickness t2 of the innermost portion of the recess 123. This is a feature that occurs when negative pressure is applied from the outside of the periphery of the gas pocket portion 120 to form the wrinkled portion 121. This will be described in detail later with reference to FIG. 6.

[0050] The gas pocket portion 120 may be formed to an initial depth d1. The initial depth d1 may be smaller than the depth d of the cup portion 110. The initial depth d1 may refer to the depth of the gas pocket portion 120 after the wrinkle portion 121 is formed.

[0051] The depth of the gas pocket portion 120 may be variable depending on the wrinkles 121. More specifically, when the wrinkles 121 contract, the depth of the gas pocket portion 120 decreases. Contraction of the wrinkles 121 may mean that the pitch p between the multiple convex portions 122 becomes smaller. Conversely, when the wrinkles 121 expand, the depth of the gas pocket portion 120 increases. Expansion of the wrinkles 121 may mean that the pitch p between the multiple convex portions 122 becomes larger.

[0052] The depth of the gas pocket portion 120 may be variable between a contracted depth d2 and an expanded depth d3. The variable range of the depth of the gas pocket portion 120 may be within a range in which the wrinkled portion 121 is not excessively deformed and the function of the wrinkled portion 121 is maintained.

[0053] 4, when the wrinkled portion 121 is maximally shrunk, the gas pocket portion 120 has a shrunk depth d2. For example, when the battery case 100 is sealed in a negative pressure chamber, the wrinkled portion 121 is shrunk so that the gas pocket portion 120 has a shrunk depth d2.

[0054] The contracted depth d2 may be smaller than the initial depth d1. More specifically, the contracted depth d2 may be 0.1 times or less the initial depth d1. If the contracted depth d2 is greater than 0.1 times the initial depth d1, the wrinkled portion 121 may not deform sufficiently when sealing the battery case 100 in the negative pressure chamber, which may cause distortion of the gas pocket portion 120.

[0055] 5, when the wrinkled portion 121 is expanded to its maximum extent, the gas pocket portion 120 has an expanded depth d3. For example, when an activation process is performed to charge and discharge the electrode assembly 200 while the battery case 100 is sealed, the internal pressure of the gas generated during the activation process causes the wrinkled portion 121 to expand so that the gas pocket portion 120 has an expanded depth d3.

[0056] The expanded depth d3 may be greater than the contracted depth d1. The expanded depth d3 may be greater than the initial depth d1. More specifically, the expanded depth d3 may be 1.2 to 1.3 times the initial depth d1. That is, the expanded depth d3 may be 12 times or more the contracted depth d2. If the expanded depth d3 is less than 1.2 times the initial depth d1, the wrinkled portion 121 may not deform sufficiently, and gas may not be sufficiently trapped in the gas pocket portion 120. Conversely, if the expanded depth d3 is more than 1.3 times the initial depth d1, the peripheral portion of the gas pocket portion 120 may be excessively stretched during the formation of the wrinkled portion 121, which may cause cracks, or the gas pocket portion 120 may be ruptured due to the internal pressure of the trapped gas.

[0057] In addition, the expanded depth d3 of the gas pocket portion 120 may be 0.7 to 1.3 times the depth d of the cup portion 110. If the expanded depth d3 is less than 0.7 times the depth d of the cup portion 110, there is a risk that gas will not be sufficiently captured in the gas pocket portion 120. Conversely, if the expanded depth d3 is more than 1.3 times the depth d of the cup portion 110, the volume of the gas pocket portion 120 will be unnecessarily large, and cracks may occur due to excessive stretching of the pouch sheet 137 during the formation of the gas pocket portion 120.

[0058] Therefore, the wrinkles 121 prevent the gas pocket 120 from being distorted by negative pressure, and increase the amount of gas that the gas pocket 120 can collect, thereby improving the stability of the activation process.

[0059] FIG. 6 is a schematic diagram of an apparatus for forming wrinkles according to one embodiment of the present invention.

[0060] 6 shows the gas pocket 120 before the wrinkles 121 (see FIG. 3) are formed. The device 10 for forming the wrinkles 121 on the periphery of the gas pocket 120 (hereinafter referred to as the wrinkle forming device) can form the wrinkles 121 by applying negative pressure from the outside of the periphery of the gas pocket 120.

[0061] More specifically, the wrinkle forming device 10 may include a plurality of support parts 11 that contact the outer peripheral edge of the gas pocket part 120 and are arranged at predetermined intervals in the depth direction of the gas pocket part 120, and a negative pressure part 12 that applies negative pressure to the outer peripheral edge of the gas pocket part 120 through the interval g between the plurality of support parts 11.

[0062] Each support portion 11 may surround the outer periphery of the gas pocket portion 120. The multiple support portions 11 may be in contact with the outer periphery of the gas pocket portion 120 at predetermined intervals in the depth direction of the gas pocket portion 120. When the negative pressure portion 12 applies negative pressure to the outer periphery of the gas pocket portion 120, each support portion 11 can support the outer periphery of the gas pocket portion 120.

[0063] In order to prevent cracks from occurring in the gas pocket portion 120, the inner end portion of the support portion 11 may be formed into a curved surface.

[0064] The negative pressure unit 12 can apply negative pressure to the outer periphery of the gas pocket portion 120 through the gaps g between the multiple support portions 11. For example, as shown in Fig. 6, the multiple gaps g communicate with a negative pressure chamber, and the negative pressure unit 12 can apply negative pressure to the negative pressure chamber. As an example, the negative pressure unit 12 may include a negative pressure pump.

[0065] Therefore, the portion of the peripheral edge of the gas pocket 120 facing the gap g is stretched outward by the negative pressure. The portion of the peripheral edge of the gas pocket 120 facing the gap g is stretched and formed as a protrusion 122 (see FIG. 3), and the portion in contact with the support part 11 becomes a recess 123.

[0066] In this way, a part of the periphery of the gas pocket 120 extends outward to form the protrusion 122, so that the remaining thickness t1 of the protrusion 122 is thinner than the remaining thickness t2 of the recess 123, as shown in FIG.

[0067] By using such a wrinkle forming device 10, the wrinkles 121 can be formed easily and quickly.

[0068] FIG. 7 is a flowchart of a method for manufacturing a secondary battery according to another embodiment of the present invention, and FIGS. 8a to 8d are schematic views sequentially illustrating the method for manufacturing a secondary battery according to another embodiment of the present invention.

[0069] A method for manufacturing a secondary battery according to another embodiment of the present invention may be a method for manufacturing a secondary battery including the battery case 100 described above.

[0070] The method for manufacturing the secondary battery may include a step (S10) of preparing a battery case 100 (hereinafter referred to as the "case preparation step"), a step (S20) of accommodating the electrode assembly 200 and the electrolyte in the cup portion 110 (hereinafter referred to as the "accommodation step"), a step (S30) of sealing the battery case 100 in a negative pressure chamber (hereinafter referred to as the "sealing step"), and a step (S40) of collecting gas generated by charging and discharging the electrode assembly 200 in the gas pocket portion 120 (hereinafter referred to as the "gas collection step").

[0071] The case preparation step (S10) can be named a "method for manufacturing a pouch-type battery case" and can itself constitute yet another embodiment of the present invention.

[0072] More specifically, the case preparation step (S10) may include a step (S11) of forming a cup portion 110 and a gas pocket portion 120 in the pouch sheet 137 (hereinafter referred to as the "first forming step"), and a step (S12) of forming a wrinkle portion 121 on the periphery of the gas pocket portion 120 that folds and stretches so that the depth of the gas pocket portion 120 can be varied depending on the internal pressure of the gas pocket portion 120 (hereinafter referred to as the "second forming step").

[0073] In the first molding step (S11), the cup portion 110 and the gas pocket portion 120 may be molded into a concave shape on the pouch sheet 137. For example, the cup portion 110 and the gas pocket portion 120 may be molded by drawing. The gas pocket portion 120 and the cup portion 110 may be formed simultaneously or sequentially in a predetermined order.

[0074] In the second forming step (S12), the wrinkle forming device 10 (see FIG. 6) can apply negative pressure to the outer periphery of the gas pocket portion 120 to form the wrinkle portion 121. This has been described above, so the details will be omitted.

[0075] The gas pocket portion 120 in which the wrinkled portion 121 is formed may have an initial depth d1. That is, in the case preparation step (S10), the gas pocket portion 120 may be formed to have an initial depth d1.

[0076] In the accommodating step (S20), with the electrode assembly 200 accommodated in the cup part 110, the folding part 140 can be folded so that the first case 101 and the second case 102 face each other.

[0077] 8a, a portion of the abutting portion between the terrace 130 of the first case 101 and the second case 102 may be heat-sealed to form a first seal portion 161. With the folding portion 140 facing downward, the first seal portion 161 may be formed along both side edges of the battery case 100. Alternatively, the edges of the first case 101 and the second case 102 opposite the folding portion 140 may be left unsealed to form an opening 150.

[0078] Then, an electrolyte solution can be injected through the opening 150. The electrolyte solution can flow into the cup portion 110 and impregnate the electrode assembly 200.

[0079] In the sealing step (S30), as shown in Fig. 8b, the opening 150 is sealed to form a second seal portion 162 that is connected to the already formed first seal portion 161. Thus, the entire battery case 100 can be sealed.

[0080] The sealing step (S30) may be performed with the battery case 100 placed in a negative pressure chamber (not shown) (e.g., a vacuum chamber). By doing so, the battery case 100 can be sealed with any gas or air remaining in the battery case 100 removed.

[0081] In the sealing step (S30), the depth of the gas pocket portion 120 may be changed to a contracted depth d2 (see FIG. 4) that is smaller than the initial depth d1. That is, the wrinkled portion 121 may be contracted and the depth of the gas pocket portion 120 may be reduced by applying negative pressure to the gas pocket portion 120 from a negative pressure chamber. This can prevent the gas pocket portion 120 from being distorted.

[0082] As mentioned above, the contracted depth d2 may be 0.1 times or less the initial depth d1.

[0083] After the battery case 100 is sealed, the electrode assembly 200 can be activated by charging or discharging the electrode assembly 200 via the electrode leads 220 protruding to the outside of the battery case 100 .

[0084] In the gas collecting step (S40), gas generated by activation of the electrode assembly 200 can be collected in the gas pocket portion 120, as shown in FIG. 8b.

[0085] In the gas collecting step (S40), the depth of the gas pocket portion 120 may be changed to an expanded depth d3 that is greater than the initial depth d1. That is, the internal pressure of the gas pocket portion 120 may increase due to the collected gas, thereby expanding the wrinkled portion 121 and increasing the depth of the gas pocket portion 120. This allows the gas pocket portion 120 to stably collect a sufficiently large amount of gas.

[0086] As mentioned above, the expanded depth d3 may be 1.2 to 1.3 times the initial depth d1.

[0087] Meanwhile, the method for manufacturing the secondary battery may further include a step (S50) of discharging gas from the gas pocket portion 120 (hereinafter referred to as the "degassing step"), and a step of further sealing the battery case 100 and cutting the gas pocket portion 120 (hereinafter referred to as the "cutting step").

[0088] In the degassing step (S50), as shown in FIG. 8c, the gas pocket portion 120 or the portion covering the gas pocket portion 120 can be punched to form at least one hole H, and gas inside the battery case 100 can be discharged through the hole H.

[0089] The degassing step (S50) may be performed while the battery case 100 is placed in a negative pressure chamber (not shown) (e.g., a vacuum chamber). By doing so, gas in the battery case 100, particularly in the gas pocket portion 120, can be quickly discharged through the hole H.

[0090] In the cutting step (S60), as shown in Fig. 8d, the gap between the cup portion 110 and the gas pocket portion 120 can be sealed to form a third seal portion 163. Both ends of the third seal portion 163 may be connected to the first seal portion 161.

[0091] Thereafter, the battery case 100 can be cut along an imaginary cutting line CL located on or outside the third sealed portion 163. Thus, a portion of the battery case 100 including the gas pocket portion 120 can be removed.

[0092] The above description merely exemplifies the technical concept of the present invention, and various modifications and variations may be made by a person having ordinary knowledge in the technical field to which the present invention pertains without departing from the essential characteristics of the present invention.

[0093] Therefore, the embodiments disclosed in the present invention are for illustrative purposes and not for limiting the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by such embodiments.

[0094] The scope of protection of the present invention should be interpreted by the appended claims, and all technical ideas within the scope equivalent thereto should be interpreted as being included in the scope of the present invention. [Explanation of symbols]

[0095] 10 Wrinkle forming device 11 Support part 12 Negative pressure section 100 Pouch-type battery case 101 Case 1 102 Case 2 110 Cup section 120 Gas pocket 121 Wrinkles 122 convex part 123 Recess 130 Terrace 140 Folding section 200 electrode assembly

Claims

1. a cup portion having a concave shape; a gas pocket portion having a concave shape and located on one side of the cup portion, The peripheral edge of the gas pocket portion is a wrinkled portion is formed that folds and stretches so that the depth of the gas pocket portion can be changed depending on the internal pressure of the gas pocket portion; The wrinkled portion is a protrusion protruding outward from the gas pocket; the protrusions and recesses are alternately positioned in a depth direction of the gas pocket portion, The remaining thickness of the convex portion is thinner than the remaining thickness of the concave portion.

2. The depth of the gas pocket is variable between a contracted depth and an expanded depth that is deeper than the contracted depth; 2. The pouch-type battery case according to claim 1, wherein the expanded depth is 0.7 to 1.3 times the depth of the cup portion.

3. The depth of the gas pocket is variable between a contracted depth and an expanded depth that is deeper than the contracted depth; 3. The pouch-type battery case according to claim 1, wherein the expanded depth is 12 times or more the contracted depth.

4. forming a cup portion and a gas pocket portion in a pouch sheet; forming a wrinkled portion on the periphery of the gas pocket portion that folds and stretches in accordance with the internal pressure of the gas pocket portion so that the depth of the gas pocket portion is variable, The wrinkled portion is a protrusion protruding outward from the gas pocket; the protrusions and recesses are alternately positioned in a depth direction of the gas pocket portion, a remaining thickness of the protrusion is thinner than a remaining thickness of the recess.

5. The gas pocket portion in which the wrinkled portion is formed has an initial depth, The method for manufacturing a pouch-type battery case according to claim 4 , wherein the depth of the gas pocket portion is variable between a contracted depth smaller than the initial depth and an expanded depth larger than the initial depth.

6. The method for manufacturing a pouch-type battery case according to claim 5 , wherein the contracted depth is 0.1 times or less the initial depth.

7. 6. The method for manufacturing a pouch-type battery case according to claim 5, wherein the expanded depth is 1.2 to 1.3 times the initial depth.

8. The device for forming the wrinkled portion includes: a plurality of support portions that are in contact with the outer periphery of the gas pocket portion and are arranged at predetermined intervals in the depth direction of the gas pocket portion; The method for manufacturing a pouch-type battery case according to claim 4 , further comprising: a negative pressure section that applies negative pressure to an outer periphery of the gas pocket section through spaces between the plurality of support sections.

9. preparing a pouch-type battery case; placing an electrode assembly and an electrolyte in a cup portion of the pouch-type battery case; sealing the pouch-shaped battery case in a negative pressure chamber; and collecting gas generated by charging and discharging the electrode assembly in a gas pocket of the pouch-type battery case, The step of preparing a pouch-type battery case includes: forming the cup portion and the gas pocket portion in a pouch sheet; forming a wrinkled portion at a peripheral edge of the gas pocket portion that folds and stretches in accordance with the internal pressure of the gas pocket portion so that the depth of the gas pocket portion is variable, The wrinkled portion is a protrusion protruding outward from the gas pocket; the protrusions and recesses are alternately positioned in a depth direction of the gas pocket portion, The method for manufacturing a secondary battery, wherein the remaining thickness of the convex portion is thinner than the remaining thickness of the concave portion.

10. In the step of preparing the pouch-type battery case, the gas pocket portion is formed to an initial depth; The method for manufacturing a secondary battery according to claim 9 , wherein in the step of sealing the pouch-shaped battery case, the depth of the gas pocket portion changes to a contracted depth that is smaller than the initial depth.

11. The method of manufacturing a secondary battery according to claim 10 , wherein in the step of collecting the gas in the gas pocket portion, the depth of the gas pocket portion changes to an expanded depth greater than the initial depth.

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