Pouch cell for secondary battery and method for manufacturing the same

Abstract

The present invention relates to a method for manufacturing a pouch cell that can prevent deterioration of the sealing quality of a pouch due to electrolyte by reducing the amount of electrolyte adhering to the sealed portion of the pouch, and to a pouch cell that can efficiently discharge gas from inside the pouch to the outside of the pouch. The pouch cell according to the present invention includes an electrode assembly, a pouch in which the electrode assembly is housed, and a gas discharge pipe that extends from the inside to the outside of the pouch, and the gas inside the pouch can permeate through the gas discharge pipe and be discharged to the outside of the pouch.

Description

Technical Field

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2023-0083458 filed on Jun. 28, 2023, 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 cell for a secondary battery and a method for manufacturing the same, and more particularly, to a rechargeable secondary battery pouch cell capable of charging and discharging and a method for manufacturing the same.

Background Art

[0003] In recent years, with the increase in the price of energy sources due to the depletion of fossil fuels and the growing concern about environmental pollution, the need for environmentally friendly alternative energy sources has become an essential and indispensable element for future life. Therefore, research on various power generation technologies such as solar power, wind power, and tidal power has been continuously carried out, and there has also been a great deal of interest in power storage devices such as batteries for more efficiently using the electrical energy thus produced.

[0004] Furthermore, with the increasing development and demand for electronic mobile devices and electric vehicles using batteries, the demand for batteries as an energy source has increased rapidly, and accordingly, many studies have been conducted on batteries that can meet various needs.

[0005] Batteries for storing electrical energy can generally be divided into primary batteries and secondary batteries. Primary batteries are disposable consumables, while secondary batteries are rechargeable batteries manufactured using materials in which the oxidation and reduction processes between current and substances can be repeated. That is, when a reduction reaction with respect to a material is performed by current, the power source is charged, and when an oxidation reaction with respect to the material is performed, the power source is discharged, and electricity is generated while such charging and discharging are repeated.

[0006] Rechargeable batteries can be classified into cylindrical cells, pouch cells, and prismatic cells, depending on their form. Of these, pouch cells can be manufactured by housing an electrode assembly, in which a positive electrode, negative electrode, separator, etc., are stacked inside a pouch, and the outside of the pouch is sealed. [Overview of the project] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide a method for manufacturing a pouch cell that can prevent deterioration of the sealing quality of the pouch due to the electrolyte by reducing the amount of electrolyte adhering to the part of the pouch that is sealed, and a pouch cell that can efficiently discharge gas from inside the pouch to the outside of the pouch. [Means for solving the problem]

[0008] The pouch cell according to the present invention includes an electrode assembly, a pouch in which the electrode assembly is housed, and a gas discharge pipe that extends from the inside to the outside of the pouch, wherein the gas inside the pouch can pass through the gas discharge pipe and be discharged to the outside of the pouch.

[0009] The gas exhaust pipe may include an inner layer and an outer layer having thermal sealing properties, and a permeable layer disposed between the inner layer and the outer layer, with higher gas permeability than the inner layer and the outer layer.

[0010] The inner and outer layers may contain polyolefin resin, and the permeable layer may contain PTFE (polytetrafluoroethylene).

[0011] The gas discharge pipe may further include a sealed portion that protrudes outside the pouch and whose inner layer is sealed by a seal.

[0012] The gas discharge pipe may further include a passage that extends from the sealed portion to the inside of the pouch and communicates with the inside of the pouch, forming a space through which gas can move.

[0013] The outer layer of the passage can be sealed to the pouch by sealing.

[0014] The pouch cell further includes electrode leads that are electrically connected to the electrode assembly and extend to the outside of the pouch, and the gas exhaust pipe can be positioned at a distance from the electrode leads.

[0015] The pouch includes a cup portion in which a space for the electrode assembly is arranged is provided, and a terrace portion that is arranged around the periphery of the cup portion and sealed, and the gas discharge pipe can be arranged in a form that is fitted into the terrace portion.

[0016] The gas discharge pipe may include a first gas discharge pipe located at one end of the pouch in the longitudinal direction and a second gas discharge pipe located at the other end of the pouch in the longitudinal direction.

[0017] The first gas discharge pipe may be positioned eccentrically on one side in the width direction of the pouch, and the second gas discharge pipe may be positioned eccentrically on the other side in the width direction of the pouch.

[0018] A method for manufacturing a pouch cell according to the present invention may include the steps of: (S1) placing a gas discharge pipe around the periphery of a pouch containing an electrode assembly; (S2) inserting an unsealed pipe configured to prevent sealing of the gas discharge pipe into the gas discharge pipe; (S3) sealing the periphery of the pouch; and (S4) injecting an electrolyte into the pouch through the gas discharge pipe.

[0019] The gas discharge pipe includes a first gas discharge pipe located at one end of the pouch in the longitudinal direction and a second gas discharge pipe located at the other end of the pouch in the longitudinal direction, wherein in step (S4), an electrolyte is injected into the pouch through the first gas discharge pipe and gas inside the pouch is removed through the second gas discharge pipe.

[0020] The method for manufacturing a pouch cell according to the present invention may include: (S1') a step of coupling the unsealed tube and the gas discharge tube such that the outer peripheral surface of the unsealed tube faces the inner peripheral surface of the gas discharge tube; (S2') a step of arranging the gas discharge tube coupled to the unsealed tube at the periphery of a pouch having an electrode assembly accommodated therein; (S3') a step of sealing the periphery of the pouch; and (S4') a step of injecting an electrolytic solution into the pouch through the unsealed tube.

[0021] The method for manufacturing a pouch cell may further include: (S5) a step of removing the unsealed tube after injecting the electrolytic solution into the pouch; and (S6) a step of sealing one end of the gas discharge tube.

Advantages of the Invention

[0022] According to a preferred embodiment of the present invention, during the sealing of the pouch in the manufacturing process of the pouch cell, the amount of the electrolytic solution adhering to the sealing portion can be reduced, and the sealing quality of the pouch can be improved.

[0023] Thereby, the sealing property of the pouch is excellent, and the stability of the pouch cell can be improved.

[0024] Also, the gas inside the pouch generated during the charging or discharging process of the pouch cell can be efficiently discharged to the outside.

[0025] Thereby, the occurrence of the bending phenomenon of the pouch caused by the gas inside the pouch can be delayed or prevented, and the safety of the pouch cell can be improved.

[0026] Also, even if bending occurs due to the pressure of the gas inside the pouch, it can be induced to bend through the gas discharge tube.

[0027] This makes it possible to predict bending and facilitates the management of the pouch cell or battery module.

[0028] The effects of the present invention are not limited to the contents exemplified above, and various other effects are included in this specification.

Brief Description of the Drawings

[0029] [Figure 1] It is a perspective view schematically showing a pouch cell according to Embodiment 1 of the present invention. [Figure 2] It is a plan view schematically showing a pouch cell according to Embodiment 1 of the present invention. [Figure 3] It is a cross-sectional view schematically showing a cross-section cut along A-A' of FIG. 1. [Figure 4] It is a perspective view schematically showing a pouch cell according to Embodiment 2 of the present invention. [Figure 5] It is a plan view schematically showing a pouch cell according to Embodiment 2 of the present invention. [Figure 6] It is a flowchart schematically showing a method for manufacturing a pouch cell according to Embodiment 3 of the present invention. [Figure 7] It is a flowchart schematically showing a method for manufacturing a pouch cell according to Embodiment 4 of the present invention. [Figure 8] It is a perspective view schematically showing a state where an unsealed tube and a gas discharge tube are combined in a method for manufacturing a pouch cell according to Embodiment 4 of the present invention. [Figure 9] It is a perspective view schematically showing a state where a gas discharge tube combined with an unsealed tube is inserted into the inside of a pouch in a method for manufacturing a pouch cell according to Embodiment 4 of the present invention.

[0030] Those skilled in the art will understand that these drawings illustrate elements simply and clearly, and are not necessarily drawn to scale. For example, to aid in understanding various embodiments, the dimensions of some elements shown in the drawings may be exaggerated compared to other elements. [Modes for carrying out the invention]

[0031] 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 or restricted by the following embodiments.

[0032] For the purpose of clearly describing the present invention, detailed descriptions of related known technologies that are irrelevant to the description or that could 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 used throughout the specification for components that are the same or similar.

[0033] Furthermore, the terms and words used in this specification and in 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 idea of ​​the present invention, in accordance with the principle that inventors may define the concepts of terms as appropriate to best describe their invention.

[0034] Pouch-type batteries have several advantages, including good space efficiency due to their filled internal space and thin construction, high energy density, and the ability to accommodate a variety of battery designs.

[0035] During the manufacturing process of pouch cells, an electrolyte solution impregnated into the electrode assembly housed inside the pouch is injected into the pouch. After removing the gas generated inside the pouch, the pouch can be sealed. However, a problem can arise where the sealing quality deteriorates due to the electrolyte solution adhering to the sealing surface of the pouch.

[0036] Therefore, in order to improve the sealing quality of the pouch, there is a need for a pouch cell manufacturing method that injects the electrolyte into the inside of the pouch so that the electrolyte does not adhere to the pouch.

[0037] Furthermore, the pressure in a pouch cell increases due to internal gases generated by repeated charging and discharging, and this increased pressure can damage the seal of the sealed portion. This reduction in the seal of the sealed portion can lead to problems such as venting, where the pouch opens due to pressure.

[0038] Therefore, since a pouch cell experiencing venting cannot function as a secondary battery, a pouch cell is needed that includes a configuration that allows the gas inside the pouch to be discharged to the outside of the pouch in order to prevent or delay the occurrence of venting.

[0039] Embodiment 1 Figure 1 is a schematic perspective view illustrating the pouch cell 10 according to Embodiment 1 of the present invention, and Figure 2 is a schematic plan view illustrating the pouch cell 10 according to Embodiment 1 of the present invention as seen from above.

[0040] The pouch cell 10 described in the present invention may mean a rechargeable and dischargeable secondary battery. Specifically, it may mean a secondary battery in which an electrode assembly 100 including a negative electrode, a positive electrode, and a separator is placed inside a pouch 200, and the pouch 200 encloses the electrode assembly 100. More specifically, the pouch cell 10 may mean a secondary battery in which an electrode assembly 100 including a negative electrode, a positive electrode, and a separator is housed inside a pouch 200 together with an electrolyte.

[0041] The pouch 200 may include a cup portion 210 and a terrace portion 220. The cup portion 210 has a space for the electrode assembly 100 to be placed, so the electrode assembly 100 can be placed in the cup portion 210 of the pouch 200. The terrace portion 220 is placed on the periphery of the cup portion 210 and can be sealed by sealing. Here, sealing may mean a process of sealing the pouch 200 by heat and pressure.

[0042] The electrode assembly 100 may have a form in which the negative electrode, positive electrode, and separator are stacked or in the form of a wound jelly roll, and the pouch 200 can house the electrode assembly 100. Specifically, the electrode assembly 100 and the electrolyte can be housed inside the molded cup portion 210 of the pouch 200.

[0043] Referring to Figure 1, the electrode lead 400 can be electrically connected to the electrode assembly 100 and positioned to protrude from the outside of the pouch 200. The electrode lead 400 protruding from the outside of the pouch 200 allows the pouch cell 10 to provide electrical energy to the outside. Therefore, the electrode lead 400 may be a conductor.

[0044] The lead film can cover the electrode lead 400 so that the pouch 200 and the electrode lead 400 are insulated from each other. Specifically, the lead film can be placed on both sides of the electrode lead 400 to cover it. The lead film can be configured in pairs and placed on each side of the electrode lead 400.

[0045] On the other hand, the lead film may contain an insulating material to insulate the pouch 200 from the electrode lead 400. The electrode lead 400 may, but is not necessarily limited to, a substantially rectangular parallelepiped shape.

[0046] As the pouch cell 10 undergoes repeated charging and discharging, gas is generated, which can increase the pressure inside the pouch 200. If the pressure inside the pouch 200 increases too much, a venting phenomenon may occur, causing the pouch to open and potentially rendering the pouch cell 10 inoperable.

[0047] Specifically, the pouch 200 of the pouch cell 10 can contain an electrolyte along with the electrode assembly 100. Inside the pouch 200 of the pouch cell 10, remaining water in the electrolyte and water that has penetrated from the outside react with the lithium salt to generate HF (hydrogen fluoride), and gases such as carbon dioxide, carbon monoxide, ethylene, and methane may be generated due to the decomposition of the electrolyte. Furthermore, depending on the material of the positive electrode contained in the electrode assembly 100 of the pouch cell 10, hydrogen and HF may be generated even more, and overheating may occur due to overcharging and internal short circuits during the charging and discharging process. As a result, a large amount of gas may be generated inside the pouch 200. Such gases can increase the pressure inside the pouch, and this increased pressure can cause swelling, where the pouch 200 swells, or venting, where a part of the pouch 200 ruptures.

[0048] In this regard, the pouch cell 10 according to Embodiment 1 of the present invention may include a gas discharge pipe 300 as an example of a configuration for efficiently discharging gas accumulated inside the pouch 200 to the outside of the pouch 200.

[0049] Referring to Figures 1 and 2, the gas exhaust pipe 300 of the pouch cell 10 can be positioned to extend from the inside to the outside of the pouch 200. Here, the gas exhaust pipe 300 can be fixed in a fitted state within the pouch 200. Specifically, the pouches 200 of the pouch cell 10 can be joined by a sealing in pairs facing each other, and the gas exhaust pipe 300 can be positioned between the portions of the pair of pouches 200 that are sealed facing each other. More specifically, the gas exhaust pipe 300 can be positioned in a form fitted into the terrace portion 220 of the pouch 200.

[0050] On the other hand, the gas inside the pouch 200 can permeate the surface of the gas discharge pipe 300 and move to the outside. Specifically, the gas collected in the cup portion 210 of the pouch 200 can diffuse into the inside of the gas discharge pipe 300, permeate the surface of the gas discharge pipe 300, and be discharged to the outside of the pouch cell 10.

[0051] Since the pouch cell 10 according to Embodiment 1 of the present invention includes a gas discharge pipe 300, the gas generated inside the pouch 200 by repeated charging and discharging can be efficiently released to the outside of the pouch 200.

[0052] Figure 3 is a schematic cross-sectional view showing a section cut along line A-A' in Figure 1.

[0053] As an example of a configuration that allows gas to permeate efficiently, the gas discharge pipe 300 of the pouch cell 10 according to Embodiment 1 of the present invention can be composed of multiple layers. Specifically, the gas discharge pipe 300 may include an inner layer 301, a permeable layer 302, and an outer layer 303.

[0054] The inner layer 301 and the outer layer 303 can have thermal sealing properties or thermal and pressure sealing properties. For example, the inner layer 301 and the outer layer 303 can contain the same material as the innermost layer of a pouch 200 that is sealed by thermal and pressure. In addition, the inner layer 301 and the outer layer 303 can partially melt and become adhesive when heated. Therefore, in addition to thermal and pressure sealing methods, sealing methods using ultrasound or the like can also be applied to the inner layer 301 and the outer layer 303.

[0055] Specifically, the inner layer 301 and outer layer 303 of the gas exhaust pipe 300 can consist of one or more materials selected from the group consisting of polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymers, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, nylon, polyester, poly(p-phenylenebenzobisoxazole), polyarylate, Teflon®, and glass fibers. In particular, polyolefin resins such as polypropylene (PP) or polyethylene (PE) can be used. Polypropylene (PP) has excellent mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, as well as chemical properties such as corrosion resistance, and can be mainly used to manufacture the inner layer 301 or outer layer 303. Furthermore, the inner layer 301 and outer layer 303 can also be composed of unoriented polypropylene (cast polypropylene), acid-modified polypropylene, or polypropylene-butylene-ethylene ternary copolymer. Here, the acid-treated polypropylene can be MAH PP (maleic anhydride-modified polypropylene).

[0056] The permeable layer 302 can be placed between the inner layer 301 and the outer layer 303. Therefore, the gas exhaust pipe 300 can be configured in the order of inner layer 301, permeable layer 302, and outer layer 303 from the inside out.

[0057] The permeable layer 302 can have high gas permeability. The inner layer 301 and outer layer 303 are gas permeable, and the gas permeability of the permeable layer 302 may be even higher than that of the inner layer 301 and outer layer 303. For example, the permeable layer 302 can contain a fluororesin with excellent gas permeability. Specifically, the permeable layer 302 can be made of PTFE (polytetrafluoroethylene).

[0058] Since the gas discharge pipe 300 includes a permeable layer 302, efficient gas discharge by permeation is possible.

[0059] As an example of a configuration to prevent the electrolyte inside the pouch 200 from leaking out, the gas discharge pipe 300 according to Embodiment 1 of the present invention may include a sealing portion 310.

[0060] The gas discharge pipe 300 can be positioned to extend from the inside to the outside of the pouch 200. Here, the sealing portion 310 can protrude to the outside of the pouch 200. If the sealing portion 310 is positioned inside the pouch 200, when the gas is discharged to the outside of the pouch 200, it must permeate both the surface of the gas discharge pipe 300 and the surface of the pouch 200. Therefore, the path through which the gas is discharged to the outside of the pouch 200 can be lengthened. That is, if the sealing portion 310 is positioned outside the pouch 200, the gas can be efficiently discharged to the outside of the pouch 200 via the surface of the gas discharge pipe 300.

[0061] The surface of the sealing portion 310 can also be composed of an inner layer 301, a permeable layer 302, and an outer layer 303, and the sealing portion 310 can be sealed by the sealing of the opposing inner layers 301. As described above, the inner layers 301 can have sealing properties due to heat and pressure. That is, the sealing portion 310 of the gas exhaust pipe 300 can be sealed by the bonding of the opposing inner layers 301 by sealing.

[0062] The area of ​​the sealing portion 310 can be determined considering the gas discharge performance of the pouch cell 10, the direction in which venting occurs, and other factors. For example, if the amount of gas generated inside the pouch 200 is greater than the amount of gas discharged through the gas discharge pipe 300, the sealing portion 310 can be guided to open and venting to occur. Here, the sealing strength can be determined by adjusting the area of ​​the sealing portion 310, and the sealing strength of the sealing portion 310 can be set to be less than the sealing strength of the pouch 200. Therefore, if necessary, venting can be guided to occur through the sealing portion 310 of the gas discharge pipe 300.

[0063] Thus, when the direction of venting through the sealed portion 310 is predicted, it is easy to respond to venting of the pouch cell 10. In other words, management of the pouch cell 10 or a battery module containing multiple pouch cells 10 is easier, and stability can be improved.

[0064] The gas discharge pipe 300 of the pouch cell 10 according to Embodiment 1 of the present invention may further include a passage portion 320.

[0065] The passage portion 320 of the gas discharge pipe 300 may have a substantially pipe shape that includes a space through which gas can pass. Furthermore, the passage portion 320 of the gas discharge pipe 300 may be positioned to extend from the sealing portion 310 to the interior of the pouch 200. Therefore, the passage portion 320 can communicate with the interior of the pouch 200 and form a space through which gas can move. The gas inside the pouch 200 moves into this formed space, and the moved gas can permeate the surface of the gas discharge pipe 300 and be discharged to the outside of the pouch 200.

[0066] The surface of the passage section 320 can also be composed of an inner layer 301, a permeable layer 302, and an outer layer 303, and the outer layer 303 of the passage section 320 can be sealed to the pouch 200 by sealing. As described above, the outer layer 303 can have sealing properties due to heat and pressure. The innermost layer of the pouch 200 can also have sealing properties due to heat and pressure. Sealing of the passage section 320 and the pouch 200 can prevent phenomena such as electrolyte leakage into the space between the gas discharge pipe 300 and the pouch 200.

[0067] On the other hand, the gas discharge pipe 300 of the pouch cell 10 according to Embodiment 1 of the present invention can be used as a passage for injecting electrolyte in the manufacturing process of the pouch cell.

[0068] In this regard, the manufacturing process of the pouch cell may include a step of injecting an electrolyte into the pouch 200 so that the electrode assembly 100 is impregnated. Conventionally, there has been a problem in that the electrolyte adheres to the sealing portion of the pouch 200, resulting in a decrease in sealing quality. However, as described in this disclosure, when the electrolyte is injected into the pouch 200 via the gas exhaust pipe 300, the sealing portion of the pouch 200 other than the gas exhaust pipe 300 portion can be almost completely sealed before the electrolyte is injected. Therefore, the electrolyte does not adhere to most of the sealing portion of the pouch 200, and the sealing quality can be improved.

[0069] The gas discharge pipe 300 of the pouch cell 10 according to Embodiment 1 of the present invention is not only used as an electrolyte inlet in the manufacturing process of the pouch cell, but can also exert a gas discharge effect on the gas generated during charging and discharging in the finished pouch cell 10. The gas discharge pipe 300 used in the manufacturing process of the pouch cell will be described in detail in Embodiment 3.

[0070] In relation to the position of the gas exhaust pipe 300, the gas exhaust pipe 300 can be positioned at a distance from the electrode lead 400. That is, the gas exhaust pipe 300 can be positioned with a gap between it and the electrode lead 400. The electrode lead 400 is electrically connected to the electrode assembly 100 and can extend to the outside of the pouch 200. For example, the electrode lead 400 can be positioned approximately in the center with respect to the width direction of the pouch 200, and the gas exhaust pipe 300 can be positioned eccentrically to one side with respect to the width direction of the pouch 200. Here, the width direction of the pouch 200 may mean the vertical direction with reference to Figure 2.

[0071] When the gas discharge pipe 300 is positioned with a gap between it and the electrode lead 400, the gas attempting to move outside the pouch 200 experiences relatively little interference with the electrode lead 400, allowing the gas to be efficiently discharged outside the pouch 200.

[0072] The finished pouch cell 10 according to Embodiment 1 of this disclosure includes a gas discharge pipe 300, which may be used in the manufacturing process for efficient electrolyte injection, and the internal gas generated during charging and discharging can be discharged to the outside through the gas discharge pipe 300. Therefore, the occurrence of venting and the like can be delayed or prevented, and the stability of the pouch cell 10 can be improved.

[0073] Embodiment 2 Figure 4 is a schematic perspective view illustrating the pouch cell 10' according to Embodiment 2 of the present invention, and Figure 5 is a schematic plan view illustrating the pouch cell 10' according to Embodiment 2 of the present invention.

[0074] In the following, a detailed explanation of the configuration of the pouch cell 10 according to Embodiment 1 of the present invention will be omitted, and the differences will be explained in detail.

[0075] The pouch cell 10' according to Embodiment 2 of the present invention may differ from the pouch cell 10 according to Embodiment 1 of the present invention in the form of the gas discharge pipe 300'.

[0076] As an example of a configuration for efficient gas discharge, the gas discharge pipe 300' of the pouch cell 10' according to Embodiment 2 of the present invention may include a first gas discharge pipe 300-1 and a second gas discharge pipe 300-2.

[0077] The first gas exhaust pipe 300-1 and the second gas exhaust pipe 300-2 can have substantially the same shape and be composed of the same layer structure. That is, the first gas exhaust pipe 300-1 and the second gas exhaust pipe 300-2 can be sealed at one end and have a three-layer structure consisting of an inner layer 301, a permeable layer 302, and an outer layer 303. The shapes of the first gas exhaust pipe 300-1 and the second gas exhaust pipe 300-2 are the same as the shape of the gas exhaust pipe 300 described in Embodiment 1 of the present invention, and a detailed explanation thereof is omitted.

[0078] Referring to Figures 4 and 5, the first gas discharge pipe 300-1 can be located at one end of the pouch 200 in the longitudinal direction, and the second gas discharge pipe 300-2 can be located at the other end of the pouch 200 in the longitudinal direction. Here, the longitudinal direction may mean the transverse direction with reference to Figure 5.

[0079] In the pouch cell 10', the gas inside the pouch 200 is discharged at two locations, the first gas discharge pipe 300-1 and the second gas discharge pipe 300-2, thereby improving gas removal performance. Furthermore, since the first gas discharge pipe 300-1 is located at one end and the second gas discharge pipe 300-2 is located at the other end on the opposite side, the gas can be discharged more efficiently.

[0080] More specifically, the first gas discharge pipe 300-1 can be positioned eccentrically on one side in the width direction of the pouch 200, and the second gas discharge pipe 300-2 can be positioned eccentrically on the other side in the width direction of the pouch 200. Here, the width direction may mean the vertical direction with reference to Figure 5.

[0081] In other words, the first gas discharge pipe 300-1 and the second gas discharge pipe 300-2 can be positioned in approximately point-symmetrical positions with respect to the center of the pouch 200. Therefore, gas can be discharged more efficiently from the pouch cell 10'.

[0082] On the other hand, the first gas discharge pipe 300-1 of the gas discharge pipe 300 according to Embodiment 2 of the present invention can be used as a passage for injecting electrolyte in the pouch cell manufacturing process. Furthermore, the second gas discharge pipe 300-2 of the gas discharge pipe 300 can be used as a passage for removing gas from inside the pouch 200 when injecting electrolyte through the first gas discharge pipe 300-1 in the pouch cell manufacturing process. That is, the second gas discharge pipe 300-2 creates a vacuum inside the pouch 200, allowing the electrolyte injected through the first gas discharge pipe 300-1 to be uniformly impregnated into the electrode assembly 100. Here, the first gas discharge pipe 300-1 and the second gas discharge pipe 300-2 are positioned approximately point-symmetrically with respect to the center of the pouch 200. Therefore, when the removal of gas from inside the pouch 200 and the injection of electrolyte are performed simultaneously in the pouch cell manufacturing process, interference between them can be reduced, improving process efficiency.

[0083] Embodiment 3 Figure 6 is a flowchart illustrating a schematic method for manufacturing pouch cells according to Embodiment 3 of the present invention.

[0084] A method for manufacturing a pouch cell according to Embodiment 3 of the present invention may include the step (S1) of arranging a gas discharge pipe 300 around the periphery of a pouch 200 containing an electrode assembly 100. Specifically, the gas discharge pipe 300 can be arranged on the terrace portion 220 of the pouch 200. Here, the gas discharge pipe 300 serves as a passage through which the electrolyte is injected and may have a substantially tubular shape.

[0085] Subsequently, step (S2) can be performed in which an unsealed pipe 500 is inserted into the gas exhaust pipe 300 located on the terrace portion 220 of the pouch 200 (see Figure 8). Here, the unsealed pipe 500 may contain a non-sealing fluororesin. Therefore, the unsealed pipe 500 can prevent the gas exhaust pipe 300 from being sealed together with the periphery of the pouch 200 when the periphery of the pouch 200 is sealed. In other words, the unsealed pipe 500 can prevent the gas exhaust pipe 300 from being sealed together with the periphery of the pouch 200 when the periphery of the pouch 200 is sealed. The unsealed pipe 500 may have a pipe shape similar to that of the gas exhaust pipe 300, and its diameter may be smaller than that of the gas exhaust pipe 300 in order to be easily inserted into the gas exhaust pipe 300.

[0086] After the unsealed pipe 500 is inserted and positioned inside the gas exhaust pipe 300, a step (S3) of sealing the periphery of the pouch 200 can be performed. Here, the outer layer 303 of the sealing gas exhaust pipe 300 and the pouch 200 can be sealed. On the other hand, since the unsealed pipe 500, which does not have sealing properties, is positioned inside the gas exhaust pipe 300, the inside of the gas exhaust pipe 300 may not be sealed even in the periphery sealing step. This is because the unsealed pipe 500 is inserted inside the gas exhaust pipe 300, and the inner layer 301 of the sealing gas exhaust pipe 300 does not come into contact with each other due to the unsealed pipe 500.

[0087] After the sealing of the pouch 200 is completed in step S3, a step (S4) can be performed in which the electrolyte is injected into the inside of the pouch 200 via the gas discharge pipe 300. In other words, in the method for manufacturing pouch cells according to Embodiment 3 of the present invention, since the electrolyte injection step is performed after the pouch sealing step, the periphery of the pouch 200 is sealed before the electrolyte adheres to the pouch 200, thereby improving the sealing quality.

[0088] On the other hand, the gas discharge pipe 300 may include a first gas discharge pipe 300-1 located at one end of the pouch 200 in the longitudinal direction, and a second gas discharge pipe 300-2 located at the other end of the pouch 200 in the longitudinal direction. Here, electrolyte can be injected into the pouch 200 via the first gas discharge pipe 300-1, and gas inside the pouch 200 can be removed via the second gas discharge pipe 300-2. Therefore, in the method for manufacturing pouch cells according to this embodiment, the electrode assembly 100 inside the pouch 200 can be more uniformly impregnated with electrolyte, and the impregnation of electrolyte can be improved.

[0089] In the electrolyte injection step (S4), after the gas inside the pouch 200 is removed via the second gas discharge pipe 300-2, the electrolyte can be injected via the first gas discharge pipe 300-1. In this case, the inside of the pouch 200 becomes nearly vacuum-sealed, and the electrode assembly 100 can be uniformly impregnated with the electrolyte.

[0090] Furthermore, the electrolyte can be injected into the first gas discharge pipe 300-1 while the gas is simultaneously removed via the second gas discharge pipe 300-2. In this case, the time required for the process is shortened, thereby improving process efficiency. Here, the longer the distance between the first gas discharge pipe 300-1 and the second gas discharge pipe 300-2, the less interference there is between gas removal and electrolyte injection.

[0091] After the electrolyte is injected into the pouch 200, a step (S5) can be performed to remove the unsealed pipe 500 from the gas exhaust pipe 300. Since the electrolyte adheres to the unsealed pipe 500 during the electrolyte injection process, relatively little electrolyte adheres to the inner layer 301 of the sealing gas exhaust pipe 300.

[0092] After the unsealed pipe 500 is removed, a step (S6) of sealing one end of the gas exhaust pipe 300 can be performed. Since the electrolyte is blocked from the unsealed pipe 500 by the inner layer 301 of the sealing gas exhaust pipe 300, and relatively little electrolyte adheres to it, the sealing quality of the gas exhaust pipe 300 can be improved. Here, the inner layers 301 facing each other at one end of the gas exhaust pipe 300 can be sealed by heat and pressure. By sealing, one end of the gas exhaust pipe 300 can be sealed, and the electrolyte inside the pouch 200 can not be leaked to the outside. Here, the area of ​​the gas exhaust pipe 300 that is sealed can be determined considering the gas exhaust performance of the completed pouch cell 10, the venting prevention pressure, etc.

[0093] The method for manufacturing pouch cells according to Embodiment 3 of the present invention improves sealing quality because the pouch 200 is sealed before the step of injecting the electrolyte into the pouch 200, that is, while the electrolyte is not adhering to the pouch 200. Therefore, venting and other issues are prevented, and the stability of the pouch cell 10 can be improved. In addition, the electrolyte is injected into the pouch 200 with the gas removed, improving the impregnation of the electrolyte. In other words, the performance and quality of the finished pouch cell 10 can be improved.

[0094] Embodiment 4 Figure 7 is a flowchart schematically illustrating the method for manufacturing a pouch cell according to Embodiment 4 of the present invention. Figure 8 is a perspective view schematically illustrating the state in which the unsealed pipe 500 and the gas discharge pipe 300 are connected in the method for manufacturing a pouch cell according to Embodiment 4 of the present invention, and Figure 9 is a perspective view schematically illustrating the state in which the gas discharge pipe 300 connected to the unsealed pipe 500 is inserted inside the pouch 200 in the method for manufacturing a pouch cell according to Embodiment 4 of the present invention.

[0095] In the following, we will omit explanations of steps that are the same as those in the method for manufacturing pouch cells according to Embodiment 3 of the present invention, and will focus on explaining the differences.

[0096] Referring to Figure 7, the method for manufacturing a pouch cell according to Embodiment 4 of the present invention may include a step (S1') of connecting the unsealed pipe 500 and the gas discharge pipe 300. That is, in the method for manufacturing a pouch cell according to Embodiment 4 of the present invention, the unsealed pipe 500 and the gas discharge pipe 300 can be connected before the gas discharge pipe 300 is placed inside the pouch 200. This differs from the method for manufacturing a pouch cell according to Embodiment 3 of the present invention, in which the unsealed pipe 500 is inserted after the gas discharge pipe 300 has been placed inside the pouch 200.

[0097] Referring to Figure 8, in step (S1'), the unsealed pipe 500 and the gas exhaust pipe 300 can be connected such that the outer surface of the unsealed pipe 500 and the inner surface of the gas exhaust pipe 300 face each other. Here, the unsealed pipe 500 can have a roughly tubular shape as it serves as a passage through which the electrolyte is injected. Furthermore, for efficient injection of the electrolyte, the length of the unsealed pipe 500 can be longer than that of the gas exhaust pipe 300.

[0098] One example of a method for connecting the gas exhaust pipe 300 and the unsealed pipe 500 is to insert and fit the unsealed pipe 500 into the gas exhaust pipe 300. Alternatively, the outer surface of the unsealed pipe 500 can be wrapped with a sheet having the same layer structure as the gas exhaust pipe 300, and then the ends of the sheet can be connected to form the gas exhaust pipe 300.

[0099] Subsequently, a step (S2') can be performed in which the gas exhaust pipe 300, which is connected to the unsealed pipe 500, is placed on the periphery of the pouch 200. Specifically, the gas exhaust pipe 300, which is connected to the unsealed pipe 500, can be placed on the terrace portion 220 of the pouch 200.

[0100] In the pouch cell 10, the diameter of the gas discharge pipe 300 can be changed depending on the required gas discharge performance or the electrolyte injection speed. If the diameter of the gas discharge pipe 300 is relatively small, the process of inserting the unsealed pipe 500 into the gas discharge pipe 300 placed inside the pouch 200 may be difficult to perform efficiently. In this regard, in the method for manufacturing a pouch cell according to Embodiment 4 of the present invention, the unsealed pipe 500 and the gas discharge pipe 300 can be connected before the gas discharge pipe 300 is placed inside the pouch 200. Therefore, the gas discharge pipe 300 and the unsealed pipe 500 can be connected relatively easily. This improves the efficiency of the pouch cell manufacturing process.

[0101] After the gas exhaust pipe 300, which is connected to the unsealed pipe 500, is placed inside the pouch 200, a step (S3') of sealing the periphery of the pouch 200 can be performed. Here, since the unsealed pipe 500, which does not have sealing properties, is placed inside the gas exhaust pipe 300, the inside of the gas exhaust pipe 300 may not be sealed by the sealing even in the step (S3') of sealing the periphery of the pouch 200.

[0102] Subsequently, a step (S4') can be performed in which the electrolyte is injected into the pouch 200 via the unsealed pipe 500. After injecting the electrolyte into the pouch 200, the process of removing the unsealed pipe 500 and sealing one end of the gas discharge pipe 300 can be the same as in Embodiment 3 of the present invention. Also, in Embodiment 4, as in Embodiment 3, since the electrolyte injection step is performed after the pouch sealing step, the periphery of the pouch 200 is sealed before the electrolyte adheres to the pouch 200, thereby improving the sealing quality.

[0103] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various implementations are possible by persons with ordinary skill in the art to which the present invention pertains, within the equivalent scope of the technical concept of the present invention and the claims described below. [Explanation of Symbols]

[0104] 10, 10', 10'' pouch cell 100 electrode assembly 200 pouches 210 cup section 220 Terrace section 300, 300' gas exhaust pipe 300-1 First gas discharge pipe 300-2 Second gas discharge pipe 301 Inner layer 302 Transparent layer 303 Outer layer 310 Sealed part 320 Passage section 400 electrode leads 500 Unsealed pipes

Claims

1. Electrode assembly and A pouch containing the electrode assembly, This includes a gas discharge pipe that extends from the inside to the outside of the pouch, A pouch cell in which the gas inside the pouch is discharged to the outside of the pouch by passing through the gas discharge pipe.

2. The aforementioned gas exhaust pipe is An inner layer and an outer layer having heat sealing properties, The pouch cell according to claim 1, comprising a permeable layer disposed between the inner layer and the outer layer, the permeable layer having higher gas permeability than the inner layer and the outer layer.

3. The inner layer and the outer layer are, Contains polyolefin resin, The aforementioned transparent layer is The pouch cell according to claim 2, comprising PTFE (polytetrafluoroethylene).

4. The aforementioned gas exhaust pipe is The pouch cell according to claim 1, further comprising a sealing portion that protrudes to the outside of the pouch and whose inner layer is sealed by a seal.

5. The aforementioned gas exhaust pipe is The pouch cell according to claim 4, further comprising a passage portion extending from the sealed portion to the interior of the pouch, and having a space formed therein that communicates with the interior of the pouch and allows gas to move.

6. The pouch cell according to claim 5, wherein the outer layer of the passage portion is sealed with the pouch by sealing.

7. The electrode assembly further includes electrode leads that are electrically connected to the electrode assembly and extend to the outside of the pouch, The aforementioned gas exhaust pipe is The pouch cell according to claim 1, wherein the electrode leads are arranged with a distance between them.

8. The aforementioned pouch is A cup portion is provided in which the electrode assembly is arranged, The pouch cell according to claim 1, comprising a terrace portion arranged around the periphery of the cup portion and sealed, wherein the gas discharge pipe is arranged in a manner fitted into the terrace portion.

9. The aforementioned gas exhaust pipe is A first gas discharge pipe is positioned at one end of the pouch in the longitudinal direction, The pouch cell according to claim 1, further comprising a second gas discharge pipe disposed at the other end of the pouch in the longitudinal direction.

10. The first gas discharge pipe is positioned eccentrically on one side in the width direction of the pouch, The pouch cell according to claim 9, wherein the second gas discharge pipe is eccentrically positioned on the other side in the width direction of the pouch.

11. (S1) A step of arranging a gas exhaust pipe around the periphery of a pouch containing an electrode assembly inside, (S2) The step of inserting an unsealed pipe, configured to prevent sealing of the gas discharge pipe, into the gas discharge pipe, (S3) The step of sealing the periphery of the pouch, A method for manufacturing a pouch cell, comprising the step of (S4) injecting an electrolyte solution into the pouch through the gas discharge pipe.

12. The aforementioned gas exhaust pipe is A first gas discharge pipe is positioned at one end of the pouch in the longitudinal direction, The pouch includes a second gas discharge pipe located at the other end in the longitudinal direction of the pouch, In step (S4) above, The electrolyte is injected into the pouch through the first gas discharge pipe. The method for manufacturing a pouch cell according to claim 11, wherein the gas inside the pouch is removed via the second gas discharge pipe.

13. (S5) After injecting the electrolyte into the pouch, the step of removing the unsealed tube, (S6) A method for manufacturing a pouch cell according to claim 11, further comprising the step of sealing one end of the gas discharge pipe.

14. The method for manufacturing a pouch cell according to claim 11, wherein the unsealed pipe contains a fluororesin that does not have sealing properties.

15. (S1') A step of connecting the unsealed pipe and the gas exhaust pipe such that the outer surface of the unsealed pipe and the inner surface of the gas exhaust pipe face each other, (S2') The step of placing the gas exhaust pipe, which is connected to the unsealed pipe, around the periphery of the pouch containing the electrode assembly inside, (S3') The step of sealing the periphery of the pouch, A method for manufacturing a pouch cell, comprising the step of (S4') injecting an electrolyte solution into the pouch through the unsealed tube.

16. (S5') After injecting the electrolyte into the pouch, the step of removing the unsealed tube, (S6') A method for manufacturing a pouch cell according to claim 15, further comprising the step of sealing one end of the gas discharge pipe.

17. The method for manufacturing a pouch cell according to claim 15, wherein the unsealed pipe contains a fluororesin that does not have sealing properties.

18. A method for manufacturing a pouch cell according to claim 16, wherein the sealing strength of one end of the sealed gas discharge pipe is set to be less than the sealing strength of the periphery of the pouch.

Images