Pouch-type battery case, method for manufacturing the same, and method for manufacturing a 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 the contents disclosed in the literature of the Korean patent application are incorporated herein by reference in their entirety.

[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 Art

[0003] Generally, a secondary battery, unlike a non-rechargeable primary battery, means a battery capable of charging and discharging, and is widely used in electronic devices such as mobile phones, notebook computers, camcorders, and electric vehicles. In particular, lithium secondary batteries have a larger capacity than nickel-cadmium batteries or nickel-metal hydride batteries and a high energy density per unit weight, so their utilization is rapidly increasing.

[0004] Secondary batteries can be classified according to the type of battery case. Typically, there are can-type secondary batteries including cylindrical battery cases and square 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 an electrode assembly and a gas pocket portion for collecting gas. The gas pocket portion may be formed by drawing using a forming device or the like, similar to the cup portion for accommodating the electrode assembly.

[0006] More specifically, the method for manufacturing a pouch-type secondary battery may include a step of sealing a part of the pouch-type battery case with the electrode assembly accommodated in the cup portion, a step of injecting an electrolyte through an unsealed opening of the pouch-type battery case, a step of sealing the opening, and a step of activating the electrode assembly by charging and discharging. Further, the gas generated in the activation step may be collected in the gas pocket portion.

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

[0008] However, due to the negative pressure, unlike the cup portion that houses the electrode assembly, the gas pocket portion may not maintain its shape and may experience distortion or deformation. If distortion or deformation occurs in the gas pocket portion, the volume of the gas pocket portion decreases, which can lead to problems in adequately collecting gas, and therefore improvements are required. [Overview of the project] [Problems that the invention aims to solve]

[0009] One problem that the present invention aims to solve is to provide a pouch-type battery case and a method for manufacturing the same that prevents distortion of the gas pocket portion due to wrinkles formed in the gas pocket portion and allows for the collection of a sufficiently large amount of gas.

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

[0011] An embodiment of the present invention may include a cup portion having a curved shape and a gas pocket portion having a curved shape located on one side of the cup portion. The periphery of the gas pocket portion may have wrinkles formed thereon that fold or unfold in accordance with the internal pressure of the gas pocket portion, so as to make the depth of the gas pocket portion variable. The wrinkles may include a convex portion that protrudes outward from the gas pocket portion and a concave portion that is alternately located 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.

[0012] The depth of the gas pocket is variable between a contraction depth and an expansion depth greater than the contraction depth, and the expansion depth may be 0.7 to 1.3 times the depth of the cup portion.

[0013] The depth of the gas pocket is variable between a contraction depth and an expansion depth greater than the contraction depth, and the expansion depth may be 12 times or more the contraction depth.

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

[0015] The gas pocket portion formed by the wrinkled portion has an initial depth, and the depth of the gas pocket portion may be variable between a shrinkage depth smaller than the initial depth and an expansion depth larger than the initial depth.

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

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

[0018] The apparatus 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, housing an electrode assembly and an electrolyte in the cup portion of the pouch-type battery case, sealing the pouch-type battery case in a negative pressure chamber, and collecting gas generated by the charging and discharging of the electrode assembly in the 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 on a pouch sheet, and forming wrinkled portions on the periphery of the gas pocket portion that fold and unfold in accordance with the internal pressure of the gas pocket portion. The wrinkled portions may include convex portions that protrude outward from the gas pocket portion and concave portions that are alternately positioned with the convex portions in the depth direction of the gas pocket portion. The remaining thickness of the convex portions may be thinner than the remaining thickness of the concave portions.

[0020] In the step of preparing the pouch-type battery case, the gas pocket portion may be molded to an initial depth, and in the step of sealing the pouch-type battery case, the depth of the gas pocket portion may be changed to a shrinkage depth 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 greater than the initial depth. [Effects of the Invention]

[0022] According to a preferred embodiment of the present invention, even if negative pressure is applied to the gas pocket when sealing the pouch-type battery case, the wrinkled portion shrinks, reducing the depth of the gas pocket. Therefore, distortion of the gas pocket can be prevented.

[0023] Furthermore, when gas is collected in the gas pocket, the internal pressure of the gas pocket increases, the wrinkles expand, and the depth of the gas pocket increases. Therefore, the gas pocket can stably collect a sufficiently large amount of gas.

[0024] In addition, effects that can be easily predicted by those skilled in the art from the configuration according to the preferred embodiment of the present invention can also be included.

Brief Description of the Drawings

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

[0026] [Figure 1] It is an assembly drawing showing a pouch-type battery case according to an embodiment of the present invention and an electrode assembly housed therein. [[ID=1)] [Figure 2] It is a perspective view of a pouch-type battery case according to an embodiment of the present invention as viewed from another direction. [Figure 3] It is a side view of a pouch-type battery case according to an embodiment of the present invention. [Figure 4] It is a diagram showing a state in which the gas pocket portion shown in FIG. 3 is contracted. [Figure 5] It is a diagram showing a state in which the gas pocket portion shown in FIG. 3 is expanded. [Figure 6] It is a schematic diagram of an apparatus for forming a wrinkled portion according to an embodiment of the present invention. [Figure 7] It is a flowchart of a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8a] It is a schematic diagram sequentially showing a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8b] It is a schematic diagram sequentially showing a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8c] It is a schematic diagram sequentially showing a method for manufacturing a secondary battery according to another embodiment of the present invention. [Figure 8d] It is a schematic diagram sequentially showing a method for manufacturing a secondary battery according to another embodiment of the present invention.

Modes for Carrying Out the Invention

[0027] Preferred embodiments of the present invention will be described in detail below with reference to the attached drawings, so that they can be easily implemented by a person with ordinary skill in the art to which the present invention pertains. However, the present invention can be realized in a variety of different forms and is not limited to or restricted to the following embodiments.

[0028] In order to clearly explain the present invention, detailed descriptions of parts unrelated to the description or related prior art that may obscure the gist of the invention have been omitted. In this specification, when assigning reference numerals to components in each drawing, the same or similar reference numerals are assigned to components that are the same or similar throughout the specification.

[0029] Furthermore, the terms and words used in this specification and the claims should not be interpreted in a manner limited to their ordinary or dictionary meanings, but rather should be interpreted in a manner consistent with the technical concept of the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best explain their invention.

[0030] Figure 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-type 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 in which multiple layers are laminated. For example, the pouch sheet 137 may include a first resin layer (e.g., polypropylene) forming one surface, a second resin layer (e.g., polyethylene terephthalate) forming the other surface, and a metal layer (e.g., aluminum) located between the first and second resin layers. The pouch sheet 137 may have flexibility and moldability.

[0032] The battery case 100 may include a cup portion 110 having a curved shape and a gas pocket portion 120 having a curved shape located on one side of the cup portion 110. The battery case 100 may further include terraces 130 located on the periphery 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. The following explanation will use the example shown in Figure 1, where the first case 101 and the second case 102 are integrally connected. 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, it is not limited to this, 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 Figure 1, the case in which the first case 101 includes both the cup portion 110 and the gas pocket portion 120, and the second case 102 does not include both the cup portion 110 and the gas pocket portion 120, will be explained as an example. Those skilled in the art will readily understand embodiments in which each of the first case 101 and the second case 102 includes both the cup portion 110 and the gas pocket portion 120.

[0035] The cup portion 110 is recessed from the terrace 130 by a predetermined depth, forming a space in which the electrode assembly 200 is housed. After the electrode assembly 200 is housed in the cup portion 110, the folding portion 140 can be folded. In this way, the second case 102 can cover the electrode assembly 200 housed in the cup portion 110. Thus, the electrode assembly 200 can be housed inside the cup portion 110.

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

[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] A wrinkled portion 121 may be formed on the periphery of the gas pocket portion 120, which folds and unfolds in accordance with the internal pressure of the gas pocket portion 120, thereby making the depth of the gas pocket portion 120 variable. The wrinkled portion 121 may have a bellows shape. More specifically, the wrinkled portion 121 may be formed such that convex portions 122 (see Figure 3) and concave portions 123 are repeated in the depth direction of the gas pocket portion 120.

[0039] On the other hand, the electrode assembly 200 may be formed with a separation membrane interposed between multiple electrodes. For example, the electrode assembly 200 may be a simple stack type in which multiple electrodes and separation membranes are alternately stacked, or a lamination and stack type in which unit cells, each laminated with an electrode and a separation membrane, are stacked. However, it is not limited to these, and the electrode assembly 200 may be a jelly-roll type in which the electrode sheet and the separation membrane sheet are wound together, a stack and folding type in which a separation membrane sheet with laminated unit cells is folded, or a z-folding type in which a separation membrane sheet with multiple electrodes 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 from the electrode assembly 200 in different directions (for example, opposite directions). However, it is not limited to this, and it goes without saying that the positive electrode tabs 211 and negative electrode tabs 212 may protrude side by side.

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

[0042] The electrode lead 220 may have one end connected to a 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 sealing the battery case 100, the insulating portion 230 may be heat-fused to the terrace 130. Thus, the insulating portion 230 can insulate the electrode leads 220 from the battery case 100 and maintain the seal of the battery case 100.

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

[0045] For the sake of explanation, Figures 2 to 5 show the first case 101 shown in Figure 1.

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

[0047] As mentioned above, the wrinkled portion 121 may have a bellows shape. More specifically, the wrinkled portion 121 may include a convex portion 122 that protrudes outward from the gas pocket portion 120 and a concave portion 123 that is alternately located with the convex portion 122 in the depth direction of the gas pocket portion 120.

[0048] The convex portion 122 may be formed to bulge outward from the gas pocket portion 120. The concave portion 123 may be formed to recess inward from the gas pocket portion 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 part of the protrusion 122 may be thinner than the remaining thickness t2 of the innermost part of the recess 123. This is a characteristic that arises from applying negative pressure from the outside of the peripheral edge of the gas pocket portion 120 to form the wrinkle portion 121. This will be described in detail later with reference to Figure 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 can mean the depth after the wrinkle portion 121 has been formed in the gas pocket portion 120.

[0051] The depth of the gas pocket portion 120 may be made variable by the wrinkle portion 121. More specifically, when the wrinkle portion 121 contracts, the depth of the gas pocket portion 120 decreases. Contraction of the wrinkle portion 121 can mean that the pitch p between the multiple protrusions 122 becomes smaller. Conversely, when the wrinkle portion 121 expands, the depth of the gas pocket portion 120 increases. Expansion of the wrinkle portion 121 can mean that the pitch p between the multiple protrusions 122 becomes larger.

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

[0053] As shown in Figure 4, when the wrinkled portion 121 is contracted to its maximum extent, the gas pocket portion 120 has a contraction depth d2. For example, when sealing the battery case 100 in a negative pressure chamber, the wrinkled portion 121 contracts so that the gas pocket portion 120 has a contraction depth d2.

[0054] The shrinkage depth d2 may be less than the initial depth d1. More specifically, the shrinkage depth d2 may be 0.1 times or less of the initial depth d1. If the shrinkage 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, and the gas pocket portion 120 may become distorted.

[0055] As shown in Figure 5, when the wrinkled portion 121 is fully expanded, the gas pocket portion 120 has an expanded depth d3. For example, when performing an activation process in which the electrode assembly 200 is charged and discharged while the battery case 100 is sealed, the internal pressure of the gas generated in the activation process causes the wrinkled portion 121 to expand so that the gas pocket portion 120 has an expanded depth d3.

[0056] The expansion depth d3 may be greater than the shrinkage depth d1. The expansion depth d3 may also be greater than the initial depth d1. More specifically, the expansion depth d3 may be 1.2 to 1.3 times the initial depth d1. That is, the expansion depth d3 may be 12 times or more the shrinkage depth d2. If the expansion 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 collected in the gas pocket portion 120. Conversely, if the expansion depth d3 is greater than 1.3 times the initial depth d1, during the molding of the wrinkled portion 121, the periphery of the gas pocket portion 120 may be excessively stretched, causing cracks, or the gas pocket portion 120 may rupture due to the internal pressure of the collected gas.

[0057] Furthermore, the expansion 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 expansion depth d3 is less than 0.7 times the depth d of the cup portion 110, there is a risk that sufficient gas will not be collected in the gas pocket portion 120. Conversely, if the expansion depth d3 is greater than 1.3 times the depth d of the cup portion 110, the volume of the gas pocket portion 120 will become unnecessarily large, and cracks may occur due to excessive stretching of the pouch sheet 137 during the molding of the gas pocket portion 120.

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

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

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

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

[0062] Each support portion 11 may surround the outer edge of the gas pocket portion 120. Multiple support portions 11 may be in contact with the outer edge 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 edge of the gas pocket portion 120, each support portion 11 can support the outer edge of the gas pocket portion 120.

[0063] To prevent cracks from occurring in the gas pocket portion 120, the inner end of the support portion 11 may be formed in a curved shape.

[0064] The negative pressure unit 12 can apply negative pressure to the outer edge of the gas pocket unit 120 via the gaps g between the multiple support units 11. For example, as shown in Figure 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 gas pocket portion 120 facing the gap g is stretched outward by the negative pressure. The portion of the gas pocket portion 120 facing the gap g is stretched and formed as a convex portion 122 (see Figure 3), and the portion in contact with the support portion 11 becomes a concave portion 123.

[0066] As a result, a portion of the peripheral edge of the gas pocket portion 120 extends outward and is formed as a convex portion 122. Therefore, as shown in Figure 3, the remaining thickness t1 of the convex portion 122 is thinner than the remaining thickness t2 of the concave portion 123.

[0067] With such a wrinkle-forming apparatus 10, the wrinkle-formed portion 121 can be formed easily and quickly.

[0068] Figure 7 is a flowchart of a method for manufacturing a secondary battery according to another embodiment of the present invention, and Figures 8a to 8d are schematic diagrams sequentially showing the method for manufacturing a secondary battery according to another embodiment of the present invention.

[0069] Another embodiment of the present invention may be a method for manufacturing a secondary battery that includes the battery case 100 described above.

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

[0071] The case preparation step (S10) can be named "Method for Manufacturing a Pouch-Type Battery Case" and can constitute yet another embodiment of the present invention.

[0072] More specifically, the case preparation step (S10) may include a step (S11) (hereinafter referred to as the "first molding step") in which a cup portion 110 and a gas pocket portion 120 are formed on the pouch sheet 137, and a step (S12) (hereinafter referred to as the "second molding step") in which wrinkled portions 121 are formed on the periphery of the gas pocket portion 120 so as to be folded or stretched in accordance with the internal pressure of the gas pocket portion 120.

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

[0074] In the second molding step (S12), the wrinkle molding apparatus 10 (see Figure 6) can form the wrinkle portion 121 by applying negative pressure to the outer edge of the gas pocket portion 120. As this has been described above, 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 an initial depth d1.

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

[0077] Subsequently, as shown in Figure 8a, the first seal portion 161 can be formed by heat-fusing a portion of the contact area between the terrace 130 of the first case 101 and the second case 102. With the folding portion 140 facing downwards, the first seal portion 161 may be formed along both side edges of the battery case 100. Alternatively, the edges opposite to the folding portion 140 of the first case 101 and the second case 102 may not be sealed, forming an opening 150.

[0078] Subsequently, the electrolyte can be injected through the opening 150. The electrolyte flows into the cup portion 110 and impregnates the electrode assembly 200.

[0079] In the sealing step (S30), as shown in Figure 8b, by sealing the opening 150, a second sealing portion 162 can be formed that connects to the already formed first sealing 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 inside a negative pressure chamber (not shown) (for example, a vacuum chamber). This allows the battery case 100 to be sealed with any remaining gas or air inside removed.

[0081] In the sealing step (S30), the depth of the gas pocket portion 120 may change to a shrinkage depth d2 (see Figure 4) that is smaller than the initial depth d1. That is, negative pressure may be applied to the gas pocket portion 120 by the negative pressure chamber, causing the wrinkled portion 121 to shrink and reducing the depth of the gas pocket portion 120. This prevents the gas pocket portion 120 from becoming distorted.

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

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

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

[0085] In the gas collection step (S40), the depth of the gas pocket portion 120 may change 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, causing the wrinkled portion 121 to expand and increasing the depth of the gas pocket portion 120. By doing so, the gas pocket portion 120 can stably collect a sufficiently large amount of gas.

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

[0087] On the other hand, the method for manufacturing the secondary battery may further include a step of discharging gas from the gas pocket portion 120 (S50) (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 Figure 8c, at least one hole H can be formed by punching holes in the gas pocket portion 120 or the portion covering the gas pocket portion 120, and the gas inside the battery case 100 can be discharged from the hole H.

[0089] The degassing step (S50) may be performed with the battery case 100 placed inside a negative pressure chamber (not shown) (for example, a vacuum chamber). This allows the gas in the battery case 100, particularly in the gas pocket portion 120, to be quickly discharged through the hole H.

[0090] In the cutting step (S60), as shown in Figure 8d, the space 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] Subsequently, the battery case 100 can be cut along a virtual cutting line CL located on or outside the third seal portion 163. Thus, a portion of the battery case 100, including the gas pocket portion 120, can be removed.

[0092] The above description is merely illustrative of the technical concept of the present invention, and any person with ordinary skill in the art to which the present invention belongs could make various modifications and alterations without departing from the essential characteristics of the present invention.

[0093] Therefore, the embodiments disclosed in this invention are for illustrative purposes only, and not to limit the technical concept of the invention, and the scope of the technical concept of the invention is not limited by such embodiments.

[0094] The scope of protection of this invention should be interpreted in accordance with the appended claims, and all technical ideas equivalent thereto should be interpreted as being included within the scope of the rights of this invention. [Explanation of Symbols]

[0095] 10 Wrinkle Forming Apparatus 11 Support part 12 Negative pressure area 100 Pouch-type Battery Cases 101 Case 1 102 Case 2 110 cup section 120 Gas pocket section 121 Wrinkle area 122 Convex part 123 Recess 130 Terrace 140 Folding section 200 electrode assembly

Claims

1. A cup portion having a curved shape, The cup portion includes a gas pocket portion located on one side of the cup portion and having an indented shape, 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 varies depending on the internal pressure of the gas pocket portion. The aforementioned wrinkled portion is, The convex portion that protrudes outward from the gas pocket portion, The gas pocket portion includes recesses that are alternately positioned with the protrusions in the depth direction, A pouch-type battery case in which the remaining thickness of the protrusion is thinner than the remaining thickness of the recess.

2. The depth of the gas pocket is variable between the contraction depth and the expansion depth which is greater than the contraction depth. The pouch-type battery case according to claim 1, wherein the expansion depth is 0.7 to 1.3 times the depth of the cup portion.

3. The depth of the gas pocket is variable between the contraction depth and the expansion depth which is greater than the contraction depth. The pouch-type battery case according to claim 1 or 2, wherein the expansion depth is 12 times or more the contraction depth.

4. The steps include forming a cup portion and a gas pocket portion on a pouch sheet, The step includes forming a wrinkled portion on the periphery of the gas pocket portion so that the depth of the gas pocket portion becomes variable depending on the internal pressure of the gas pocket portion, The aforementioned wrinkled portion is, The convex portion that protrudes outward from the gas pocket portion, The gas pocket portion includes recesses that are alternately positioned with the protrusions in the depth direction, A method for manufacturing a pouch-type battery case, wherein the remaining thickness of the protrusion is thinner than the 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 contraction depth smaller than the initial depth and an expansion depth larger than the initial depth.

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

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

8. The apparatus for forming the wrinkled portion is: Multiple support portions 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, A method for manufacturing a pouch-type battery case according to any one of claims 4 to 7, further comprising a negative pressure section that applies negative pressure to the outer edge of the gas pocket section via the spacing between the plurality of support sections.

9. The steps include preparing a pouch-type battery case, The steps include: housing the electrode assembly and electrolyte in the cup portion of the pouch-type battery case; The steps include sealing the pouch-type battery case inside a negative pressure chamber, The step includes collecting the gas generated by the charging and discharging of the electrode assembly into the gas pocket of the pouch-type battery case, The step of preparing the aforementioned pouch-type battery case is: The steps include forming the cup portion and the gas pocket portion on the pouch sheet, The step includes forming a wrinkled portion on the periphery of the gas pocket portion so that the depth of the gas pocket portion becomes variable depending on the internal pressure of the gas pocket portion, The aforementioned wrinkled portion is, The convex portion that protrudes outward from the gas pocket portion, The gas pocket portion includes recesses that are alternately positioned with the protrusions in the depth direction, A method for manufacturing a secondary battery, wherein the remaining thickness of the protrusion is thinner than the remaining thickness of the recess.

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-type battery case, the depth of the gas pocket portion changes to a shrinkage depth smaller than the initial depth.

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

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