Battery case for lithium secondary battery suppressing deformation of electrode assembly

Abstract

To provide a battery case capable of suppressing such a phenomenon that gas generated in an activation step deforms an electrode assembly before a deaeration step.SOLUTION: A battery case 100 for lithium secondary batteries composed of a laminate sheet including a structure of an outer layer / a barrier layer / an inner layer includes a first region 121, and a second region which is a remaining region excluding the first region. The laminate sheet configuring the first region has excellent gas permeability or excellent expansibility as compared with a laminate sheet configuring the second region which is the other region excluding the first region. The laminate sheet configuring the first region includes no barrier layer. The outer layer of the laminate sheet in the first region is made of one or more members selected from a group consisting of low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), biaxial oriented polypropylene (BOPP), and cyclic olefin copolymer (COC).SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] This application claims the benefit of priority to Korean Patent Application No. 10-2019-0132219, filed on October 23, 2019, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a battery case for a lithium secondary battery, and more particularly to a pouch-type battery case for suppressing deformation of an electrode assembly during an activation process. [Background technology]

[0003] As technological development and demand for mobile devices increases, the demand for secondary batteries as an energy source is rapidly increasing. Among such secondary batteries, lithium secondary batteries, which have high energy density and discharge voltage, have been the subject of much research and are now commercially available and widely used.

[0004] Lithium secondary batteries are broadly classified into cylindrical batteries, prismatic batteries, pouch batteries, etc. depending on their external shape, and are also classified into lithium ion batteries, lithium ion polymer batteries, lithium polymer batteries, etc. depending on the form of the electrolyte.

[0005] Due to the recent trend toward miniaturization of mobile devices, the demand for thin rectangular batteries and pouch-type batteries is increasing, and there is particularly high interest in pouch-type batteries, which are easy to modify in shape, have low manufacturing costs, and are small in weight.

[0006] Generally, a pouch-type battery refers to a battery in which an electrode assembly and an electrolyte are sealed inside a pouch-type case of a laminate sheet composed of a resin layer and a metal layer. The electrode assembly housed in the battery case has a jelly-roll type (wound type), stack type (laminate type), or composite type (stack / folded type) structure. A pouch-type secondary battery is manufactured by forming a receiving portion for mounting an electrode assembly in a laminate sheet, and, with the electrode assembly mounted in the receiving portion, heat-sealing a separate sheet separated from the sheet or a sheet extending from the sheet to seal the electrode assembly.

[0007] 1 shows a cross-sectional view of a laminate sheet for a pouch-type secondary battery, and referring to this, the laminate sheet (20) has a structure in which an outer layer (21), a barrier layer (22), and an inner layer (23) are laminated in this order. The outer layer (21) has a function of protecting the battery from the outside, the barrier layer (22) has a function of preventing the inflow or leakage of foreign matter such as gas and moisture and a function of improving the strength of the battery case, and the inner layer (23) has a function of enabling heat fusion when sealing the battery case.

[0008] FIG. 2 is a front view of a conventional battery cell in which an electrode assembly is received in a pouch of a laminate sheet and a sealing process is completed, and FIG. 3 is a side view of the battery cell of FIG. 2. Referring to these drawings, a battery case (10) includes a receiving portion (11) in which an electrode assembly (1) is received, a sealing portion (13) formed by heat-sealing a laminate sheet, and a gas pocket portion (12) that can collect gas generated during an activation process as a surplus space other than the receiving portion. However, during the activation process, gas is generated inside as shown in FIG. 3. However, the barrier layer of the laminate sheet that constitutes the battery case is difficult for gas and moisture to permeate, and has a small expansion rate. Therefore, there is a problem that the gas collected inside the battery case causes the electrode assembly to expand or deform. After the activation process, a degassing process is performed to pierce the gas pocket and discharge the internal gas, but the internal gas generated before the degassing process causes the above-mentioned problems inside the battery case.

[0009] In addition, in order to transport the battery cells during the activation process, it is necessary to pick up the battery cells using a transport member such as tongs. However, if the inside of the battery case is swollen with gas, it is difficult to pick up the battery cells using tongs as shown in FIG.

[0010] Therefore, there is a need to develop a technology for a battery case that can suppress deformation of the electrode assembly caused by gas generated during the activation process while facilitating the transfer of the battery cell for the next process. Summary of the Invention [Problem to be solved by the invention]

[0011] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide a battery case capable of suppressing a phenomenon in which gas generated during an activation process causes deformation of an electrode assembly before a deaeration process.

[0012] Another object of the present invention is to provide a battery cell that is easily picked up by a transport member by making it easier for gas generated during the activation process to be discharged or by expanding a gas pocket portion. [Means for solving the problem]

[0013] The battery case of the present invention for solving the above problems is a battery case for a lithium secondary battery made of a laminate sheet having an outer layer / barrier layer / inner layer structure, and includes a first region that is a region from which gas is easily discharged or which is relatively more likely to expand, and a second region that is the remaining region excluding the first region. The laminate sheet constituting the first region does not include a barrier layer or includes a barrier layer with slits formed therein.

[0014] A battery case according to one embodiment of the present invention includes a receiving portion in which an electrode assembly is accommodated and a gas pocket portion in which gas generated during an activation process is collected, and the first region is formed in the gas pocket portion.

[0015] In one embodiment of the present invention, the barrier layer is aluminum or an aluminum alloy.

[0016] In one embodiment of the present invention, the laminate sheet constituting the first region does not include a barrier layer. In this case, the outer layer of the laminate sheet of the first region is One or more selected from the group consisting of polyamide, polyester, polyethylene, polypropylene (PP) and cyclic olefin copolymer (COC); Alternatively, it may be one or more selected from the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP) and cyclic olefin copolymer (COC).

[0017] In one embodiment of the present invention, the laminate sheet constituting the first region includes a barrier layer having a slit formed therein, and the inner layer and the outer layer of the laminate sheet constituting the first region may not have a slit formed therein.

[0018] In one embodiment of the present invention, the first region is formed between a receiving portion side end of the gas pocket and a sealing portion side end of the gas pocket.

[0019] In one embodiment of the invention, the inner layer is polypropylene or polyethylene.

[0020] The method for manufacturing a secondary battery according to the present invention includes the steps of accommodating an electrode assembly in the battery case and injecting an electrolyte, and performing an activation process in a state where the battery case is sealed or provisionally sealed.

[0021] In addition, the method for manufacturing a secondary battery according to the present invention may further include, after the activation process, performing a degassing process of drilling one or more through holes in the gas pocket portion to discharge internal gas. Effect of the Invention

[0022] In the battery case according to the present invention, a part of the laminate sheet constituting the gas pocket does not include a barrier layer that blocks gas and moisture, or a slit is formed only in the barrier layer, so that gas inside the battery case can be easily discharged through the part, or the part of the part has a relatively superior expansibility compared to other parts, so that gas generated during the activation process moves to the part, thereby preventing deformation of the electrode assembly due to the internal gas.

[0023] In addition, the battery case according to the present invention has an advantage that the gas generated during the activation process is discharged, which reduces the degree of swelling due to gas inside the gas pocket during the activation process and makes it easier to pick up the battery cells using a transfer member, thereby improving the work efficiency in the process. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a cross-sectional view of a typical laminate sheet that constitutes a case for a pouch-type secondary battery. [Diagram 2] FIG. 1 is a front view of a battery cell in which an electrode assembly is inserted into a conventional battery case, and electrolyte is injected and sealed. [Diagram 3] 3A-3C are side views of the battery cell of FIG. 2, showing before and after an activation process. [Figure 4] 3 is a diagram showing a manner in which the battery cell in FIG. 2 is picked up. [Diagram 5] 2 is a front view of a battery cell in which an electrode assembly is inserted into a battery case according to an embodiment of the present invention, and electrolyte is injected and sealed. [Figure 6] 6A-6C are side views of the battery cell of FIG. 5, showing before and after an activation process. [Figure 7]6 is a diagram showing a manner in which the battery cell in FIG. 5 is picked up. [Figure 8] 4A to 4C are side views of a battery cell in which an electrode assembly is inserted into a battery case according to another embodiment of the present invention, and electrolyte is injected and sealed, showing before and after an activation process. [Figure 9] 4A to 4C are side views of a battery cell in which an electrode assembly has been inserted into a battery case according to another embodiment of the present invention, and electrolyte has been injected and sealed, showing before and after an activation process. [Figure 10] 1 is a diagram illustrating a battery case according to various embodiments of the present invention; [Figure 11] 1 is a diagram illustrating a battery case according to various embodiments of the present invention; [Figure 12] 1 is a diagram illustrating a battery case according to various embodiments of the present invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] As used throughout the present specification, terms such as "comprise" or "have" are intended to specify the presence of any feature, number, step, operation, component, part, or combination thereof described in the specification, and should be understood as not precluding the presence or additional possibility of one or more different features, numbers, steps, operations, components, parts, or combinations thereof.

[0026] The present invention will be described in detail below.

[0027] The present invention provides a battery case for a lithium secondary battery, which is made of a laminate sheet having an outer layer / barrier layer / inner layer structure, and includes a first region that is a region from which gas is easily discharged or which is relatively more likely to expand, and a second region that is the remaining region excluding the first region, and is characterized in that the laminate sheet constituting the first region does not include a barrier layer or includes a barrier layer with slits formed therein.

[0028] The manufacturing process of a lithium secondary battery includes a process of inserting an electrode assembly into a battery case made of a laminate sheet, injecting an electrolyte, sealing the battery case, and performing an activation process. During the activation process, a large amount of gas is generated due to chemical reactions and side reactions between the electrolyte and the electrodes, and such gas is discharged through a separate process such as a degassing process. Therefore, from the start of the activation process until the degassing process, the inside of the battery case is filled with internal gas, which may cause problems such as swelling or deformation of the electrode assembly. This is caused by the fact that the laminate sheet used as the battery case includes a barrier layer made of a metallic material that is difficult for air and water vapor to permeate. As a result, the internal gas generated during the activation process is blocked from the outside by the barrier layer and is not discharged, but is collected inside the battery case, causing the battery case to swell up like a balloon.

[0029] Therefore, the present invention has been devised to provide a structure in which the internal gas generated during the activation process is easily discharged or the internal gas is easily captured in a gas pocket portion that is not a receiving portion.

[0030] The battery case of the present invention is characterized in that the laminate sheet constituting a part of the battery case does not include a barrier layer or includes a barrier layer with slits formed therein, unlike the laminate sheet constituting the other part. A typical laminate sheet has a barrier layer made of a metallic material to prevent the inflow or leakage of foreign matter such as gas and moisture and to improve the strength of the battery case. However, due to such a barrier layer, gas generated during the activation process cannot be discharged and the inside of the battery case becomes densely packed. Therefore, the battery case of the present invention is configured such that a first region, which is a part of the battery case, is made of a laminate sheet that is easy to discharge gas or is relatively easily expanded, and a second region, which is the remaining region excluding the first region, is made of a typical laminate sheet.

[0031] 5 is a front view of a battery case (100) according to an embodiment of the present invention, in which the battery case (100) includes a receiving portion (110) in which an electrode assembly (1) having a structure of a positive electrode / separator / negative electrode is received, a gas pocket portion (120) disposed on the upper portion of the receiving portion to collect gas generated during an activation process, and a sealing portion (130) for sealing the inside of the battery case, and includes a first region (121) in a portion of the gas pocket portion (120) from which gas is easily discharged or which is relatively easily expanded. The first region may have a predetermined width and extend in a direction parallel to the sealing portion (130) of the battery case.

[0032] Fig. 10 shows the shape of the first region according to another embodiment of the present invention. Referring to Fig. 10, a plurality of rectangular first regions (121) on the gas pocket portion (120) may be arranged in a row in a direction parallel to the sealing portion (130).

[0033] It is preferable that the first region (121) is formed between the boundary where the receiving portion (110) contacts one end of the gas pocket portion (120) and the other end of the gas pocket portion, because a considerable amount of electrolyte is accommodated in the receiving portion that accommodates the electrode assembly, and if the laminate sheet constituting the receiving portion loses its barrier layer, the electrolyte may leak.

[0034] The area occupied by the first region may be suitably selected depending on the air permeability of the materials of the inner and outer layers constituting the laminate sheet and the chemical properties of the electrode assembly and the electrolyte. Specifically, the area occupied by the first region may be 5% to 50% based on the area of ​​the gas pocket portion, but is not limited thereto.

[0035] In order to facilitate the discharge of gas or to make the first region relatively easy to expand, the laminate sheet constituting the first region does not include a barrier layer or includes a barrier layer with slits formed therein. A laminate sheet without a barrier layer has a higher gas and moisture permeability than a laminate sheet with a barrier layer, so that the gas can be discharged easily. A laminate sheet with slits formed in the barrier layer can easily discharge gas even if it includes a barrier layer, because the gas can be discharged through the slits in the barrier layer.

[0036] The laminate sheet constituting the first region will now be described in detail.

[0037] The first embodiment of the laminate sheet constituting the first region does not include a barrier layer, and the materials of the outer layer and the inner layer are the same as those of a normal laminate sheet.

[0038] In the first embodiment, the outer layer of the laminate sheet constituting the first region must have excellent resistance to the external environment in order to protect the battery from the outside, and therefore is required to have excellent tensile strength and weather resistance compared to its thickness. For example, polyamide resins such as nylon, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polystyrene resins such as polystyrene, polyvinyl chloride resins, and polyvinylidene chloride resins may be used. Such materials may be used alone or in combination of two or more.

[0039] In the first embodiment, the inner layer of the laminate sheet constituting the first region functions to be heat-sealed during temporary sealing or sealing of the battery case. The heat-sealing can be performed at a temperature of 100°C to 200°C. Therefore, the material of the inner layer is made of a material having a melting point in the above temperature range. In addition, since the inner layer plays a role in ensuring insulation, it must have low hygroscopicity to suppress the intrusion of the electrolyte, and must not expand or be eroded by the electrolyte. Preferable examples of such inner layer materials include, but are not limited to, polyethylene, polyethylene acrylic acid, non-oriented polypropylene, polyamide, polyamideimide, polyimide, and mixtures or copolymers thereof.

[0040] In the first embodiment, the laminate sheet constituting the first region does not include a barrier layer and is composed of only an outer layer and an inner layer. The outer layer and the inner layer are made of the polymer material as described above, and therefore have better expansion properties than a normal laminate sheet. Therefore, the internal gas generated during the activation process naturally moves from the receiving portion that is not expanded by the barrier layer to the first region that has good expansion properties. FIG. 8 shows a side view of a battery cell in which an electrode assembly (1) is inserted into a battery case according to the first embodiment of the present invention, and electrolyte is injected and sealed, before and after the activation process. Referring to FIG. 8, the laminate sheet constituting the first region (121) has relatively better expansion properties as the barrier layer is removed, compared to the laminate sheet constituting the remaining region excluding the first region. Therefore, the gas generated during the activation process has a tendency to move to the first region (121) that expands more. As a result, most of the internal gas is captured in the first region (121) located above the gas pocket portion (121) and expands the laminate sheet in the first region, and only a small amount of gas remains in the battery cell receiving portion (110). This reduces the volume expansion rate of the battery cell receiving portion (110), making it easier for the tongs to pick up the battery cell in the subsequent process.

[0041] The second embodiment of the laminate sheet constituting the first region of the present invention does not include a barrier layer, and is made of an outer layer material that is more breathable than the outer layer material of a normal laminate sheet. FIG. 6 shows a side view of a battery cell in which an electrode assembly (1) is inserted into a battery case according to the second embodiment, and electrolyte is injected and sealed, before and after an activation process. Referring to FIG. 6, the laminate sheet constituting the first region (121) is the same as the first embodiment in that it does not include a barrier layer. However, it differs from the first embodiment in that the outer layer of the laminate sheet constituting the first region (121) is made of a material that allows gas to pass through easily but blocks moisture.

[0042] Specific examples of the material of the outer layer having the property of allowing gas to pass through easily but blocking moisture include one or more materials selected from the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP) and cyclic olefin copolymer (COC). When the outer layer of the laminate sheet constituting the first region is made of the above polymer material, it has a superior moisture blocking performance compared to normal outer layer materials, and therefore the moisture blocking performance of the first region can be maintained at a similar level to that of a laminate sheet including a barrier layer, or at a slightly lower level.

[0043] 6, the laminate sheet constituting the first region (121) has its barrier layer removed, and the outer layer material allows gas to pass through easily, so that the internal gas (a) generated during the activation process can be efficiently discharged through the first region. Therefore, the battery cell receiving portion (110) is not expanded by the internal gas. This makes it easy to pick up the battery cell, as shown in FIG. 7.

[0044] The third embodiment of the laminate sheet constituting the first region of the present invention includes a barrier layer having slits formed therein. In this case, it is preferable that the slits are formed only in the barrier layer, and that no slits are formed in the outer and inner layers. If slits are formed in the outer and inner layers, electrolyte may leak during the activation process, adversely affecting battery performance. FIG. 9 shows a side view of a battery cell in which an electrode assembly (1) is inserted into a battery case according to the third embodiment, electrolyte is injected, and the battery cell is sealed, before and after the activation process. Referring to FIG. 9, the laminate sheet constituting the first region (121) does not include a barrier layer, and the outer layer is made of a material with good air permeability, which facilitates gas discharge, and the internal gas (a) generated during the activation process is discharged well through the first region.

[0045] 11 and 12 show various shapes of slits according to the third embodiment. The slits in the barrier layer of the third embodiment may be formed in a straight line shape in the gas pocket portion (120) as shown in Fig. 11, or in a cross shape as shown in Fig. 12.

[0046] The laminate sheet forming the second region in the battery case of the present invention will be described below.

[0047] In the present invention, the second region refers to the remaining region excluding the first region. The laminate sheet constituting the second region is different from the laminate sheet of the first region, and a normal laminate sheet can be used.

[0048] A typical laminate sheet may include an outer layer / barrier layer / inner layer structure. The outer layer must have excellent resistance to the external environment in order to protect the battery from the outside, and is therefore required to have excellent tensile strength and weather resistance compared to its thickness. For example, polyamide resins such as nylon, polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN), polyolefin resins such as polyethylene (PE) and polypropylene (PP), polystyrene resins such as polystyrene, polyvinyl chloride resins, and polyvinylidene chloride resins may be used. These materials may be used alone or in combination of two or more.

[0049] The barrier layer may be made of aluminum or an aluminum alloy so as to exhibit a function of preventing the inflow or leakage of foreign matter such as gas and moisture as well as a function of improving the strength of the battery case, and these may be used alone or in combination.

[0050] The inner layer serves to allow the battery case to be heat-sealed during temporary sealing or sealing. The heat-sealing can be performed at a temperature of 100°C to 200°C. Therefore, the material of the inner layer is made of a material having a melting point in the above temperature range. In addition, since the inner layer plays a role in ensuring insulation, it must have low hygroscopicity to suppress the intrusion of the electrolyte, and must not expand or be eroded by the electrolyte. Preferable examples of such inner layer materials include, but are not limited to, polyethylene, polyethylene acrylic acid, non-oriented polypropylene, polyamide, polyamideimide, polyimide, and mixtures or copolymers thereof.

[0051] Usually, polyolefin resins such as polypropylene have low adhesive strength with metals. In order to improve the adhesive strength, the surface of the barrier layer facing the inner layer may be chemically and / or physically treated so that a large number of irregularities may be formed. Such irregularities may be formed, for example, by sandblasting or chemical etching the surface of the barrier layer, and an improvement in adhesive strength may be expected by securing a larger surface area. The size of the irregularities is not particularly limited, but is preferably 10 to 100 μm in size so as to provide a high bonding strength between the layers.

[0052] The laminate sheet may have a structure further including an adhesive layer between the outer layer and the barrier layer and / or between the barrier layer and the inner layer. The adhesive layer plays a role of complementing the adhesive force between the barrier layer and the outer layer and between the barrier layer and the inner layer.

[0053] As the adhesive layer, for example, an adhesive containing an epoxy-based, phenol-based, melamine-based, polyimide-based, polyester-based, urethane-based resin or the like may be used, and a melt-extruded resin layer formed by melt-extrusion coating a (modified) polypropylene or (modified) polyethylene resin may be used.

[0054] The laminate sheet constituting the second region may have a thickness of 5 to 40 μm for the outer layer, 5 to 100 μm for the barrier layer, and 10 to 50 μm for the inner layer. If the thickness is too thin, it is difficult to expect improvements in the barrier function and strength, and conversely, if it is too thick, it is undesirable because it reduces processability and induces an increase in the sheet thickness.

[0055] The present invention provides a method for manufacturing a secondary battery by performing an activation process using the battery case, comprising the steps of accommodating an electrode assembly in the battery case and injecting an electrolyte solution therein, and performing an activation process in a state where the battery case is sealed or provisionally sealed.

[0056] The activation process includes an aging process in which the electrolyte is sufficiently impregnated into the battery after the electrolyte is injected and sealed, and an activation process in which the battery is activated by charging / discharging at a predetermined SOC. The activation process may also include a process of applying a certain pressure simultaneously with or after charging / discharging in order to prevent by-reaction gases from being trapped between the electrodes and the separator.

[0057] In one embodiment, the method for manufacturing a secondary battery according to the present invention may further include, after the activation process, performing a degassing process of drilling one or more through-holes in the gas pocket portion to discharge internal gas.

[0058] The method for manufacturing a secondary battery according to the present invention has an effect of suppressing a phenomenon in which an electrode assembly is swollen or deformed by internal gas generated during an activation process, as the internal gas is discharged through the first region or moves to the first region which expands relatively well. In addition, when the battery cell is picked up by a transfer member such as tongs for the next process, since the internal gas has been discharged from the battery case, it is easier to pick up the battery cell compared to a battery cell whose battery case is expanded by internal gas, and has an advantage of improving the convenience of the process. The following items are also disclosed: [Item 1] A battery case for a lithium secondary battery, comprising a laminate sheet having an outer layer / barrier layer / inner layer structure, The inflatable bladder includes a first region, which is a region from which gas is easily discharged or which is relatively well expanded, and a second region, which is a region remaining excluding the first region, The battery case, wherein the laminate sheet constituting the first region does not include a barrier layer or includes a barrier layer having slits formed therein. [Item 2] The battery case is The electrode assembly includes a receiving portion and a gas pocket portion for collecting gas generated during the activation process. 2. The battery case of item 1, wherein the first region is formed in the gas pocket portion. [Item 3] 2. The battery case of item 1, wherein the barrier layer is aluminum or an aluminum alloy. [Item 4] 3. The battery case according to item 2, wherein the laminate sheet constituting the first region does not include a barrier layer. [Item 5] 2. The battery case according to item 1, wherein the laminate sheet constituting the first region includes a barrier layer having a slit formed therein. [Item 6] The first region is 5. The battery case according to item 4, wherein the gas pocket is formed between an end of the gas pocket on the receiving portion side and an end of the gas pocket on the sealing portion side. [Item 7] 5. The battery case according to item 4, wherein the outer layer of the laminate sheet in the first region is one or more selected from the group consisting of polyamide, polyester, polyethylene, polypropylene (PP), and cyclic olefin copolymer (COC). [Item 8] 5. The battery case according to item 4, wherein the outer layer of the laminate sheet in the first region is one or more selected from the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP), and cyclic olefin copolymer (COC). [Item 9] 2. The battery case of item 1, wherein the inner layer is polypropylene or polyethylene. [Item 10] 6. The battery case according to item 5, wherein the inner layer and the outer layer of the laminate sheet in the first region are not formed with slits. [Item 11] 11. Placing the electrode assembly in a battery case according to any one of items 1 to 10 and injecting an electrolyte; and The method for manufacturing a secondary battery includes the step of performing an activation process in a state where the battery case is sealed or provisionally sealed. [Item 12] 12. The method for manufacturing a secondary battery according to item 11, further comprising the step of performing a degassing process after the activation process, in which one or more through holes are drilled in a gas pocket portion included in the battery case to discharge internal gas.

Claims

1. A battery case for a lithium secondary battery, comprising a laminate sheet having an outer layer / barrier layer / inner layer structure, The laminate sheet includes a first region and a second region, which is the remaining region excluding the first region, and the laminate sheet constituting the first region has a higher gas permeability or a higher expansiveness than the laminate sheet constituting the second region, which is the remaining region excluding the first region; The laminate sheet constituting the first region does not include a barrier layer, The outer layer of the laminate sheet in the first region is one or more selected from the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP) and cyclic olefin copolymer (COC); The battery case is The electrode assembly includes a receiving portion and a gas pocket portion for collecting gas generated during the activation process. The first region is formed in the gas pocket portion, The first region is The gas pocket is formed between an end of the gas pocket on the receiving portion side and an end of the gas pocket on the sealing portion side, The first region has a predetermined width and extends in a direction parallel to the sealing portion of the battery case, or has a plurality of rectangular shapes and is arranged in a row in a direction parallel to the sealing portion.

2. The battery case of claim 1 , wherein the inner layer is polypropylene or polyethylene.

3. 3. The method of claim 1, further comprising the steps of: accommodating an electrode assembly in the battery case according to claim 1 or 2 and injecting an electrolyte; and The method for manufacturing a secondary battery includes the step of performing an activation process in a state where the battery case is sealed or provisionally sealed.

4. A step of housing the electrode assembly in a battery case and injecting an electrolyte; and performing an activation process in a sealed or provisionally sealed state of the battery case; a step of performing a degassing process after the activation process, in which one or more through holes are drilled in a gas pocket portion included in the battery case to discharge gas therein; The battery case is A battery case for a lithium secondary battery, comprising a laminate sheet having an outer layer / barrier layer / inner layer structure, The laminate sheet includes a first region and a second region, which is the remaining region excluding the first region, and the laminate sheet constituting the first region has a higher gas permeability or a higher expansiveness than the laminate sheet constituting the second region, which is the remaining region excluding the first region; The laminate sheet constituting the first region does not include a barrier layer, The method for manufacturing a secondary battery, wherein the outer layer of the laminate sheet in the first region is one or more selected from the group consisting of low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), biaxially oriented polypropylene (BOPP) and cyclic olefin copolymer (COC).

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