Pouch cell for secondary battery and manufacturing method thereof

Abstract

The present invention relates to: a pouch cell manufacturing method which can reduce the amount of an electrolyte smeared on a sealed portion of a pouch, thereby preventing the sealing quality of the pouch from being degraded by the electrolyte; and a pouch cell which can efficiently discharge internal gas in a pouch to the outside of the pouch. The pouch cell according to the present invention comprises: an electrode assembly; a pouch in which the electrode assembly is accommodated; and a gas discharge tube arranged to extend from the inside to the outside of the pouch, wherein internal gas in the pouch can pass through the gas discharge tube and be discharged to the outside of the pouch.

Description

Pouch cell for secondary battery and method for manufacturing the same

[0001] Cross-citation with related applications

[0002] This application is based upon and claims priority to Korean Patent Application No. 10-2023-0083458, filed with the Korean Intellectual Property Office on June 28, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a pouch cell for a secondary battery and a method for manufacturing the same, and more specifically, to a pouch cell for a secondary battery capable of being charged and discharged and a method for manufacturing the same.

[0005] In recent years, rising energy prices due to the depletion of fossil fuels and growing concerns about environmental pollution have made the demand for eco-friendly alternative energy sources essential for future living. Research is continuing into various power generation technologies, such as solar, wind, and tidal power. Furthermore, significant interest is being focused on power storage devices, such as batteries, to more efficiently utilize the generated electricity.

[0006] Moreover, with the technological development and increasing demand for battery-powered electronic mobile devices and electric vehicles, the demand for batteries as an energy source is rapidly increasing, and accordingly, much research is being conducted on batteries that can meet various needs.

[0007] Batteries that store electrical energy can generally be divided into primary and secondary batteries. Primary batteries are disposable, consumable batteries, whereas secondary batteries are rechargeable batteries manufactured using materials capable of repeatable oxidation and reduction processes between current and a substance. In other words, when current causes a reduction reaction in a material, the battery is charged, and when an oxidation reaction occurs in the material, the battery is discharged. This repeated charging and discharging process generates electricity.

[0008] Secondary batteries can be classified into cylindrical cells, pouch cells, and prismatic cells based on their shape. Among them, pouch cells can be manufactured by housing an electrode assembly in which a positive electrode, a negative electrode, a separator, etc. are laminated inside a pouch, and sealing the outer part of the pouch.

[0009] The object of the present invention is to provide a method for manufacturing a pouch cell capable of preventing the sealing quality of a pouch from being deteriorated by the electrolyte by reducing the amount of electrolyte applied to a portion to be sealed in the pouch, and a pouch cell capable of efficiently discharging gas inside the pouch to the outside of the pouch.

[0010] A pouch cell according to the present invention includes an electrode assembly, a pouch in which the electrode assembly is accommodated, and a gas discharge pipe arranged to extend from the inside to the outside of the pouch, wherein gas inside the pouch can pass through the gas discharge pipe and be discharged to the outside of the pouch.

[0011] The above gas discharge pipe may include an inner layer and an outer layer having heat-sealing properties, and a permeable layer disposed between the inner layer and the outer layer and having higher gas permeability than the inner layer and the outer layer.

[0012] The inner and outer layers may include a polyolefin resin, and the permeable layer may include PTFE (Polytetrafluoroethylene).

[0013] The above gas discharge pipe may further include a sealing portion that protrudes outside the pouch and has an inner layer sealed by a seal.

[0014] The above gas discharge pipe may further include a passage extending from the sealing portion to the inside of the pouch and communicating with the inside of the pouch to form a space through which gas can move.

[0015] The outer layer of the above passageway can be sealed by the pouch and sealing.

[0016] The pouch cell further includes an electrode lead electrically connected to the electrode assembly and extending to the outside of the pouch, and the gas discharge tube can be positioned at a distance from the electrode lead.

[0017] The above pouch includes a cup portion having a space therein in which the electrode assembly is placed, and a terrace portion that is placed on the edge of the cup portion and sealed, and the gas discharge pipe can be placed in a form fitted to the terrace portion.

[0018] The gas discharge pipe may include a first gas discharge pipe arranged at one end in the longitudinal direction of the pouch, and a second gas discharge pipe arranged at the other end in the longitudinal direction of the pouch.

[0019] The first gas discharge pipe may be arranged eccentrically on one side of the width direction of the pouch, and the second gas discharge pipe may be arranged eccentrically on the other side of the width direction of the pouch.

[0020] A method for manufacturing a pouch cell according to the present invention may include the steps of (S1) arranging a gas discharge tube on the edge of a pouch having an electrode assembly accommodated therein, (S2) inserting a non-sealing tube configured to prevent sealing of the gas discharge tube into the interior of the gas discharge tube, (S3) sealing the edge of the pouch, and (S4) injecting an electrolyte into the interior of the pouch through the gas discharge tube.

[0021] The gas discharge pipe includes a first gas discharge pipe arranged at one end of the length direction of the pouch, and a second gas discharge pipe arranged at the other end of the length direction of the pouch, and in the step (S4), an electrolyte can be injected into the pouch through the first gas discharge pipe, and a gas inside the pouch can be removed through the second gas discharge pipe.

[0022] A pouch cell manufacturing method according to the present invention may include a step of (S1') joining a non-sealing tube and a gas discharge tube so that the outer surface of the non-sealing tube and the inner surface of the gas discharge tube face each other, a step of (S2') arranging the gas discharge tube joined to the non-sealing tube on the edge of a pouch having an electrode assembly accommodated therein, a step of (S3') sealing the edge of the pouch, and a step of (S4') injecting an electrolyte into the interior of the pouch through the non-sealing tube.

[0023] The pouch cell manufacturing method may further include a step of (S5) removing the unsealed tube after injecting an electrolyte into the pouch, and a step of (S6) sealing one end of the gas discharge tube.

[0024] According to a preferred embodiment of the present invention, in a pouch cell manufacturing process, the amount of electrolyte applied to a sealing portion during pouch sealing can be reduced, thereby improving the sealing quality of the pouch.

[0025] Accordingly, the sealing property of the pouch can be improved, thereby improving the stability of the pouch cell.

[0026] In addition, the gas inside the pouch generated during the charging or discharging process of the pouch cell can be efficiently discharged to the outside.

[0027] Accordingly, the safety of the pouch cell can be improved by delaying or preventing the venting phenomenon of the pouch caused by the gas inside the pouch.

[0028] Additionally, even if venting occurs due to pressure from the gas inside the pouch, the venting can be induced to occur through the gas discharge pipe.

[0029] Accordingly, venting can be predicted, making it easier to manage pouch cells or battery modules.

[0030] The effects according to the present invention are not limited to the contents exemplified above, and more diverse effects are included in this specification.

[0031] FIG. 1 is a perspective view schematically illustrating a pouch cell according to Example 1 of the present invention.

[0032] FIG. 2 is a plan view schematically illustrating a pouch cell according to Example 1 of the present invention.

[0033] Figure 3 is a cross-sectional view schematically illustrating a cross-section taken along line A-A' of Figure 1.

[0034] Figure 4 is a perspective view schematically illustrating a pouch cell according to Example 2 of the present invention.

[0035] FIG. 5 is a plan view schematically illustrating a pouch cell according to Example 2 of the present invention.

[0036] Figure 6 is a flowchart schematically illustrating a pouch cell manufacturing method according to Example 3 of the present invention.

[0037] Figure 7 is a flowchart schematically illustrating a pouch cell manufacturing method according to Example 4 of the present invention.

[0038] FIG. 8 is a perspective view schematically illustrating a state in which a non-sealing tube and a gas discharge tube are combined in a pouch cell manufacturing method according to Example 4 of the present invention.

[0039] FIG. 9 is a perspective view schematically illustrating a state in which a gas discharge tube combined with a non-sealing tube is inserted inside a pouch in a pouch cell manufacturing method according to Example 4 of the present invention.

[0040] Those skilled in the art will appreciate that the drawings illustrate elements simply and clearly and are not necessarily drawn to scale. For example, to facilitate understanding of various embodiments, the dimensions of some elements depicted in the drawings may be exaggerated relative to other elements.

[0041] Hereinafter, with reference to the attached drawings, preferred embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be implemented in various different forms and is not limited or restricted by the following examples.

[0042] In order to clearly explain the present invention, a detailed description of a part that is irrelevant to the description or a related known technology that may unnecessarily obscure the gist of the present invention has been omitted, and when adding reference signs to components of each drawing in this specification, the same or similar reference signs are attached to the same or similar components throughout the specification.

[0043] In addition, terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0044] Pouch-type batteries have advantages such as high space efficiency due to their filled internal space and thin manufacturing, high energy density, and the possibility of various battery designs.

[0045] During the pouch cell manufacturing process, an electrolyte impregnated with an electrode assembly contained within the pouch is injected into the pouch, and the gas generated within the pouch is removed before the pouch is sealed. However, the electrolyte may remain on the sealed surface of the pouch, potentially degrading the sealing quality.

[0046] Therefore, there is a need for a method for manufacturing a pouch cell that injects electrolyte into the interior of a pouch without contaminating the pouch with electrolyte so as to improve the sealing quality of the pouch.

[0047] Additionally, pouch cells experience increased pressure due to internal gas generated by repeated charging and discharging. This increased pressure can damage the sealing of the sealed portion. This reduced sealing of the sealed portion can lead to problems such as venting, where the pouch opens under pressure.

[0048] Therefore, since a pouch cell in which a venting phenomenon occurs cannot function as a secondary battery, there is a need for a pouch cell including a configuration that can discharge gas inside the pouch to the outside of the pouch in order to prevent or delay the occurrence of the venting phenomenon.

[0049] Example 1

[0050] FIG. 1 is a perspective view schematically illustrating a pouch cell (10) according to Embodiment 1 of the present invention, and FIG. 2 is a plan view schematically illustrating a pouch cell (10) according to Embodiment 1 of the present invention as viewed from above.

[0051] The pouch cell (10) described in the present invention may refer to a secondary battery capable of being charged and discharged. Specifically, it may refer to 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) surrounds the electrode assembly (100). More specifically, the pouch cell (10) may refer to a secondary battery in which an electrode assembly (100) including a negative electrode, a positive electrode, and a separator is accommodated inside a pouch (200) together with an electrolyte.

[0052] The pouch (200) may include a cup portion (210) and a terrace portion (220). Since the cup portion (210) provides a space in which the electrode assembly (100) is placed, the electrode assembly (100) may be placed in the cup portion (210) of the pouch (200). In addition, the terrace portion (220) may be placed on the edge of the cup portion (210) and sealed by sealing. Here, the sealing may refer to a process of sealing the pouch (200) by heat and pressure.

[0053] The electrode assembly (100) may have a stacked form of a cathode, anode, and a separator or a rolled jelly-roll form, and the pouch (200) may accommodate the electrode assembly (100). Specifically, the electrode assembly (100) and the electrolyte may be accommodated inside the molded cup portion (210) of the pouch (200).

[0054] Referring to FIG. 1, the electrode lead (400) may be electrically connected to the electrode assembly (100) and may be positioned to protrude outside the pouch (200). The pouch cell (10) may provide electrical energy to the outside by the electrode lead (400) protruding outside the pouch (200). Accordingly, the electrode lead (400) may be a conductor.

[0055] The lead film may cover the electrode lead (400) so that the pouch (200) and the electrode lead (400) are insulated from each other. Specifically, the lead film may be placed on both sides of the electrode lead (400) to cover the electrode lead (400). The lead films may be configured as a pair and may be placed on each side of the electrode lead (400).

[0056] Meanwhile, the lead film may include an insulating material to insulate the pouch (200) and the electrode lead (400). The electrode lead (400) may have an approximately rectangular parallelepiped shape, but is not necessarily limited thereto.

[0057] As the pouch cell (10) is repeatedly charged and discharged, gas may be generated, which may increase the pressure inside the pouch (200). If the pressure inside the pouch (200) increases excessively, a venting phenomenon, in which the pouch opens, may occur, causing the pouch cell (10) to lose its function.

[0058] Specifically, an electrolyte may be accommodated together with an electrode assembly (100) inside the pouch (200) of the pouch cell (10). At this time, residual moisture of the electrolyte inside the pouch (200) of the pouch cell (10) or moisture that has penetrated from the outside may react with a lithium salt to generate HF (hydrogen fluoride), and gases such as carbon dioxide, carbon monoxide, ethylene, and methane may be generated due to decomposition of the electrolyte. In addition, depending on the material of the positive electrode included in the electrode assembly (100) of the pouch cell (10), hydrogen and HF may be additionally generated, which may cause overheating due to overcharging and internal short circuit during the charging and discharging process. Accordingly, a large amount of gas may be generated inside the pouch (200). The pressure inside the pouch may increase due to such gas, and the increased pressure may cause a swelling phenomenon in which the pouch (200) swells or a venting phenomenon in which a portion of the pouch (200) bursts.

[0059] In this regard, the pouch cell (10) according to Example 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).

[0060] Referring to FIGS. 1 and 2, the gas discharge pipe (300) of the pouch cell (10) may be arranged to extend from the inside to the outside of the pouch (200). At this time, the gas discharge pipe (300) may be fixed in a state of being fitted to the pouch (200). Specifically, the pouches (200) of the pouch cell (10) may be joined in pairs facing each other through sealing, and the gas discharge pipe (300) may be arranged between the portions of the pouch (200) that face each other and are sealed. More specifically, the gas discharge pipe (300) may be arranged in a form fitted to the terrace portion (220) of the pouch (200).

[0061] Meanwhile, the gas inside the pouch (200) can move to the outside by penetrating the surface of the gas discharge pipe (300). Specifically, the gas captured in the cup portion (210) of the pouch (200) can diffuse to the inside of the gas discharge pipe (300) and be discharged to the outside of the pouch cell (10) by penetrating the surface of the gas discharge pipe (300).

[0062] The pouch cell (10) according to Example 1 of the present invention can efficiently discharge gas generated inside the pouch (200) to the outside of the pouch (200) through repetition of charging and discharging by including a gas discharge pipe (300).

[0063] Figure 3 is a cross-sectional view schematically illustrating a cross-section taken along line A-A' of Figure 1.

[0064] As an example of a configuration that allows efficient gas permeation, the gas discharge pipe (300) of the pouch cell (10) according to Example 1 of the present invention may 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).

[0065] The inner layer (301) and the outer layer (303) may have sealing properties by heat or by heat and pressure. For example, the inner layer (301) and the outer layer (303) may include the same material as the innermost layer of the pouch (200) that is sealed by heat and pressure. In addition, the inner layer (310) and the outer layer (303) may partially melt due to heat and have adhesive properties. Therefore, in addition to the sealing method by heat and pressure, a sealing method using ultrasonic waves or the like may also be applied to the inner layer (310) and the outer layer (303).

[0066] Specifically, the inner layer (301) and the outer layer (303) of the gas discharge pipe (300) may be made 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, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fiber. In particular, a polyolefin resin such as polypropylene (PP) or polyethylene (PE) may be mainly used. Polypropylene (PP) has excellent mechanical properties such as tensile strength, rigidity, surface hardness, wear resistance, and heat resistance, and chemical properties such as corrosion resistance, and thus may be mainly used to manufacture the inner layer (301) or the outer layer (303). Furthermore, the inner layer (301) and the outer layer (303) may be composed of cast polypropylene, acid-modified polypropylene, or a polypropylene-butylene-ethylene terpolymer. Here, the acid-modified polypropylene may be MAH PP (maleic anhydride polypropylene).

[0067] The permeable layer (302) may be arranged between the inner layer (301) and the outer layer (303). Accordingly, the gas discharge pipe (300) may be configured in the order of the inner layer (301), the permeable layer (302), and the outer layer (303) from the inner side to the outer side.

[0068] The permeable layer (302) may have high gas permeability. The inner layer (301) and the outer layer (303) have gas permeability, and the permeable layer (302) may have higher gas permeability than the inner layer (301) and the outer layer (303). For example, the permeable layer (302) may include a fluorine-based resin having excellent gas permeability. Specifically, the permeable layer (302) may be made of PTFE (Polytetrafluoroethylene).

[0069] The gas discharge pipe (300) includes a permeable layer (302) to enable efficient gas discharge through permeation.

[0070] As an example of a configuration for preventing the electrolyte inside the pouch (200) from leaking out to the outside, the gas discharge pipe (300) according to Example 1 of the present invention may include a sealing portion (310).

[0071] The gas discharge pipe (300) may be arranged in a form extending from the inside to the outside of the pouch (200). At this time, the sealing portion (310) may protrude to the outside of the pouch (200). If the sealing portion (310) is arranged inside the pouch (200), when the gas is discharged to the outside of the pouch (200), it must penetrate both the surface of the gas discharge pipe (300) and the surface of the pouch (200). Therefore, the path by which the gas is discharged to the outside of the pouch (200) may be lengthened. That is, since the sealing portion (310) is arranged on the outside of the pouch (200), the gas can be efficiently discharged to the outside of the pouch (200) through the surface of the gas discharge pipe (300).

[0072] The surface of the sealing portion (310) may also be composed of an inner layer (301), a permeable layer (302), and an outer layer (303), and the sealing portion (310) may be sealed by sealing of the inner layers (301) facing each other. As described above, the inner layer (301) may have sealing properties due to heat and pressure. That is, the sealing portion (310) of the gas discharge pipe (300) may be sealed by bonding the inner layers (301) facing each other by sealing.

[0073] The area of ​​the sealing portion (310) can be determined in consideration of the gas discharge performance of the pouch cell (10), the direction in which venting occurs, etc. For example, if the amount of gas generated inside the pouch (200) is greater than the amount of gas discharged by the gas discharge pipe (300), the sealing portion (310) can be opened to induce venting. At this time, 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 weaker than the sealing strength of the pouch (200). Therefore, if necessary, venting can be induced to occur through the sealing portion (310) of the gas discharge pipe (300).

[0074] If the venting direction through the sealing portion (310) is predicted in this way, it is easy to prepare for venting of the pouch cell (10) even if it progresses. In other words, management of the pouch cell (10) or a battery module including multiple pouch cells (10) can be facilitated, and stability can be improved.

[0075] The gas discharge pipe (300) of the pouch cell (10) according to Example 1 of the present invention may further include a passage portion (320).

[0076] The passageway (320) of the gas discharge pipe (300) may have a roughly pipe shape including a space therein through which gas can pass. In addition, the passageway (320) of the gas discharge pipe (300) may be arranged to extend from the sealing portion (310) to the interior of the pouch (200). Therefore, the passageway (320) may be in communication with the interior of the pouch (200) to form a space through which gas can move. The gas inside the pouch (200) moves into the space thus formed, and the moved gas can be discharged to the exterior of the pouch (200) by penetrating the surface of the gas discharge pipe (300).

[0077] The surface of the passageway (320) may also be composed of an inner layer (301), a permeable layer (302), and an outer layer (303), and the outer layer (303) of the passageway (320) may be sealed by sealing with the pouch (200). As described above, the outer layer (303) may have sealing properties due to heat and pressure. In addition, the innermost layer of the pouch (200) may also have sealing properties due to heat and pressure. By sealing the passageway (320) and the pouch (200), a phenomenon in which the electrolyte leaks into the space between the gas discharge pipe (300) and the pouch (200) may be prevented.

[0078] Meanwhile, the gas discharge pipe (300) of the pouch cell (10) according to Example 1 of the present invention can be used as a passage for injecting an electrolyte in the pouch cell manufacturing process.

[0079] In this regard, the pouch cell manufacturing process may include a process of injecting an electrolyte into the interior of the pouch (200) so that the electrode assembly (100) is impregnated. Conventionally, there was a problem that the sealing quality was poor because the electrolyte was contaminated in the sealing portion of the pouch (200). However, as in the present disclosure, when the electrolyte is injected into the interior of the pouch (200) through the gas discharge pipe (300), most of the sealing portion of the pouch (200) except for the gas discharge pipe (300) portion can be sealed before the electrolyte is injected. Therefore, since most of the sealing portion of the pouch (200) is not contaminated with the electrolyte, the sealing quality can be improved.

[0080] The gas discharge pipe (300) of the pouch cell (10) according to Example 1 of the present invention can not only be used as an electrolyte injection port in the manufacturing process of the pouch cell, but can also exert a gas discharge effect on gas generated during charging and discharging in the finished pouch cell (10). The gas discharge pipe (300) used in the pouch cell manufacturing process is described in detail in Example 3.

[0081] With respect to the position of the gas discharge pipe (300), the gas discharge pipe (300) may be positioned spaced apart from the electrode lead (400). That is, the gas discharge pipe (300) may be positioned with a gap between it and the electrode lead (400). The electrode lead (400) may be electrically connected to the electrode assembly (100) and may extend to the outside of the pouch (200). For example, the electrode lead (400) may be positioned approximately in the center with respect to the width direction of the pouch (200), and the gas discharge pipe (300) may 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 FIG. 2.

[0082] When the gas discharge pipe (300) is positioned with a gap from the electrode lead (400), the gas trying to move to the outside of the pouch (200) is subject to relatively little interference from the electrode lead (400), so the gas can be efficiently discharged to the outside of the pouch (200).

[0083] The finished pouch cell (10) according to Example 1 of the present disclosure includes a gas discharge pipe (300). This gas discharge pipe (300) is also used for efficient electrolyte injection during the manufacturing process, and internal gas generated during charging and discharging can be discharged to the outside through the gas discharge pipe (300). Therefore, this can delay or prevent venting and the like from occurring, thereby improving the stability of the pouch cell (10).

[0084] Example 2

[0085] FIG. 4 is a perspective view schematically illustrating a pouch cell (10') according to Embodiment 2 of the present invention, and FIG. 5 is a plan view schematically illustrating a pouch cell (10') according to Embodiment 2 of the present invention.

[0086] Hereinafter, a detailed description of the same configuration as that of the pouch cell (10) according to Example 1 of the present invention will be omitted, and the differences will be mainly described.

[0087] The pouch cell (10') according to Embodiment 2 of the present invention may have a different shape of the gas discharge pipe (300') from the pouch cell (10) according to Embodiment 1 of the present invention.

[0088] As an example of a configuration for efficient gas discharge, the gas discharge pipe (300') of the pouch cell (10') according to Example 2 of the present invention may include a first gas discharge pipe (300-1) and a second gas discharge pipe (300-2).

[0089] The first gas discharge pipe (300-1) and the second gas discharge pipe (300-2) may have approximately the same shape and may be configured with the same layer structure. That is, the first gas discharge pipe (300-1) and the second gas discharge pipe (300-2) may have one end sealed and may have a three-layer structure of an inner layer (301), a permeable layer (302), and an outer layer (303). Since the shape of each of the first gas discharge pipe (300-1) and the second gas discharge pipe (300-2) may be similar to the shape of the gas discharge pipe (300) described in Example 1 of the present invention, a detailed description thereof will be omitted.

[0090] Referring to FIGS. 4 and 5, the first gas discharge pipe (300-1) may be arranged at one end of the length direction of the pouch (200), and the second gas discharge pipe (300-2) may be arranged at the other end of the length direction of the pouch (200). Here, the length direction may mean the horizontal direction based on FIG. 5.

[0091] Since the gas inside the pouch (200) in the pouch cell (10') is discharged through two places, the first gas discharge pipe (300-1) and the second gas discharge pipe (300-2), the gas removal performance can be improved. In addition, since the first gas discharge pipe (300-1) is arranged at one end and the second gas discharge pipe (300-2) is arranged at the opposite end, the gas can be discharged more efficiently.

[0092] More specifically, the first gas discharge pipe (300-1) may be arranged eccentrically on one side of the width direction of the pouch (200), and the second gas discharge pipe (300-2) may be arranged eccentrically on the other side of the width direction of the pouch (200). Here, the width direction may mean the vertical direction based on FIG. 5.

[0093] That is, the first gas discharge pipe (300-1) and the second gas discharge pipe (300-2) can be arranged at approximately point-symmetrical positions centered around the center of the pouch (200). Accordingly, gas can be discharged more efficiently from the pouch cell (10').

[0094] Meanwhile, 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 an electrolyte in the pouch cell manufacturing process. In addition, the second gas discharge pipe (300-2) of the gas discharge pipe (300) can be used as a passage for removing gas inside the pouch (200) when injecting an 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) so that the electrolyte injected through the first gas discharge pipe (300-1) can be evenly impregnated into the electrode assembly (100). At this time, the first gas discharge pipe (300-1) and the second gas discharge pipe (300-2) are arranged at approximately point-symmetrical positions centered on the center of the pouch (200). Therefore, when gas removal and electrolyte injection inside the pouch (200) are performed simultaneously in the pouch cell manufacturing process, interference between them is reduced and process efficiency can be improved.

[0095] Example 3

[0096] Figure 6 is a flowchart schematically illustrating a pouch cell manufacturing method according to Example 3 of the present invention.

[0097] A method for manufacturing a pouch cell according to Example 3 of the present invention may include a step (S1) of arranging a gas discharge pipe (300) on the edge of a pouch (200) having an electrode assembly (100) accommodated therein. Specifically, the gas discharge pipe (300) may be arranged on a terrace portion (220) of the pouch (200). Here, the gas discharge pipe (300) may have an approximately tubular shape, as it serves as a passage through which an electrolyte is injected.

[0098] Thereafter, a step (S2) of inserting a non-sealing tube (500) into the inside of a gas discharge tube (300) arranged in a terrace portion (220) of a pouch (200) may be performed (see FIG. 8). At this time, the non-sealing tube (500) may include a fluorine-based resin having no sealing properties. Therefore, the non-sealing tube (500) may prevent the gas discharge tube (300) from being sealed together when the edge of the pouch (200) is sealed. That is, the non-sealing tube (500) may prevent the gas discharge tube (300) from being sealed together when the edge of the pouch (200) is sealed. The non-sealing tube (500) may have a similar tube shape to the gas discharge tube (300), and may have a diameter smaller than that of the gas discharge tube (300) in order to be easily inserted into the inside of the gas discharge tube (300).

[0099] After the unsealed tube (500) is inserted and placed inside the gas discharge tube (300), a step (S3) of sealing the edge of the pouch (300) may be performed. At this time, the outer layer (303) of the gas discharge tube (300) having sealing properties and the pouch (200) may be sealed by sealing. On the other hand, since the unsealed tube (500) without sealing properties is placed inside the gas discharge tube (300), the inside of the gas discharge tube (300) may not be sealed by sealing even in the edge sealing step. This is because since the unsealed tube (500) is inserted inside the gas discharge tube (300), the inner layer (301) of the gas discharge tube (300) having sealing properties by the unsealed tube (500) does not come into contact with each other.

[0100] After the sealing of the pouch (200) is completed in step S3, a step (S4) of injecting an electrolyte into the interior of the pouch (200) through a gas discharge pipe (300) may be performed. That is, in the pouch cell manufacturing method according to Example 3 of the present invention, since the electrolyte injection process is performed after the pouch sealing process, the edge of the pouch (200) is sealed before the pouch (200) is immersed in the electrolyte, so the sealing quality can be improved.

[0101] Meanwhile, the gas discharge pipe (300) may include a first gas discharge pipe (300-1) arranged at one end of the length direction of the pouch (200) and a second gas discharge pipe (300-2) arranged at the other end of the length direction of the pouch (200). At this time, the electrolyte may be injected into the interior of the pouch (200) through the first gas discharge pipe (300-1), and the gas inside the pouch (200) may be removed through the second gas discharge pipe (300-2). Therefore, in the pouch cell manufacturing method according to the present embodiment, the electrode assembly (100) inside the pouch (200) may be more evenly impregnated with the electrolyte, thereby improving the electrolyte impregnation property.

[0102] In the electrolyte injection step (S4), after the gas inside the pouch (200) is removed through the second gas discharge pipe (300-2), the electrolyte can be injected through the first gas discharge pipe (300-1). In this case, since the inside of the pouch (200) becomes approximately vacuum, the electrolyte can be evenly impregnated into the electrode assembly (100).

[0103] Additionally, while the electrolyte is injected into the first gas discharge pipe (300-1), gas may be removed through the second gas discharge pipe (300-2). In this case, the time consumed 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.

[0104] After the electrolyte is injected into the pouch (200), a step (S5) of removing the unsealed tube (500) from the gas discharge tube (300) may be performed. Since the electrolyte is applied to the unsealed tube (500) during the electrolyte injection process, relatively little electrolyte may be applied to the inner layer (301) of the gas discharge tube (300) having sealing properties.

[0105] After the unsealed tube (500) is removed, a step (S6) of sealing one end of the gas discharge tube (300) can be performed. Since the electrolyte is blocked by the unsealed tube (500) on the inner layer (301) of the gas discharge tube (300) having sealing properties, relatively little electrolyte is present, so the sealing quality of the gas discharge tube (300) can be improved. At this time, the inner layers (301) facing each other at one end of the gas discharge tube (300) can be sealed with heat and pressure. By the sealing, one end of the gas discharge tube (300) can be sealed, and the electrolyte inside the pouch (200) can be prevented from leaking to the outside. Here, the sealed area of ​​the gas discharge tube (300) can be determined in consideration of the gas discharge performance of the completed pouch cell (10), the venting prevention pressure, etc.

[0106] The method for manufacturing a pouch cell according to Example 3 of the present invention can improve sealing quality because the pouch (200) is sealed before the process of injecting the electrolyte into the pouch (200), i.e., without the electrolyte contaminating the pouch (200). Accordingly, venting, etc., can be prevented, thereby improving the stability of the pouch cell (10). In addition, since the electrolyte is injected into the pouch (200) while the gas has been removed, the impregnation property of the electrolyte can be improved. In other words, the performance and quality of the finished pouch cell (10) can be improved.

[0107] Example 4

[0108] Fig. 7 is a flowchart schematically illustrating a pouch cell manufacturing method according to Embodiment 4 of the present invention. Fig. 8 is a perspective view schematically illustrating a state in which a non-sealing tube (500) and a gas discharge tube (300) are combined in a pouch cell manufacturing method according to Embodiment 4 of the present invention, and Fig. 9 is a perspective view schematically illustrating a state in which a gas discharge tube (300) combined with a non-sealing tube (500) is inserted into a pouch (200) in a pouch cell manufacturing method according to Embodiment 4 of the present invention.

[0109] Hereinafter, descriptions of steps identical to those of the pouch cell manufacturing method according to Example 3 of the present invention will be omitted and differences will be mainly described.

[0110] Referring to FIG. 7, the pouch cell manufacturing method according to the fourth embodiment of the present invention may include a step (S1') of combining a non-sealing tube (500) and a gas discharge tube (300). That is, in the pouch cell manufacturing method according to the fourth embodiment of the present invention, the non-sealing tube (500) and the gas discharge tube (300) may be combined first before arranging the gas discharge tube (300) inside the pouch (200). This is different from the pouch cell manufacturing method according to the third embodiment of the present invention in which the non-sealing tube (500) is inserted after arranging the gas discharge tube (300) inside the pouch (200).

[0111] Referring to Fig. 8, in step (S1'), the unsealed tube (500) and the gas discharge tube (300) can be coupled such that the outer surface of the unsealed tube (500) and the inner surface of the gas discharge tube (300) face each other. Here, the unsealed tube (500) serves as a passage through which the electrolyte is injected, and thus can have an approximate tube shape. In addition, for efficient electrolyte injection, the length of the unsealed tube (500) can be longer than that of the gas discharge tube (300).

[0112] As an example of a method of connecting a gas discharge pipe (300) and a non-sealing pipe (500), the non-sealing pipe (500) may be inserted and fitted into the inside of the gas discharge pipe (300). In addition, a method of forming a gas discharge pipe (300) by wrapping a sheet having the same layer structure as that of the gas discharge pipe (300) around the outer surface of the non-sealing pipe (500) and then connecting both ends of the sheet is also possible.

[0113] Thereafter, a step (S2') of arranging a gas discharge pipe (300) combined with a non-sealing pipe (500) on the edge of a pouch (200) may be performed. Specifically, the gas discharge pipe (300) combined with a non-sealing pipe (500) may be arranged on a terrace portion (220) of the pouch (200).

[0114] The diameter of the gas discharge pipe (300) may vary depending on the gas discharge performance required in the pouch cell (10) or the injection speed of the electrolyte. 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) arranged inside the pouch (200) may be difficult to proceed efficiently. In this regard, in the pouch cell manufacturing method according to Embodiment 4 of the present invention, the unsealed pipe (500) and the gas discharge pipe (300) may be joined before the gas discharge pipe (300) is arranged inside the pouch (200). Therefore, the gas discharge pipe (300) and the unsealed pipe (500) can be joined relatively easily. Through this, the efficiency of the pouch cell manufacturing process can be improved.

[0115] After the gas discharge pipe (300) combined with the unsealed pipe (500) is placed inside the pouch (200), a step (S3') of sealing the edge of the pouch (200) may be performed. At this time, since the unsealed pipe (500) without sealing property is placed inside the gas discharge pipe (300), even in the step (S3') of sealing the edge of the pouch (200), the inside of the gas discharge pipe (300) may not be sealed by sealing.

[0116] Thereafter, a step (S4') of injecting an electrolyte into the interior of the pouch (200) through the unsealed tube (500) may be performed. After injecting the electrolyte into the pouch (200), the unsealed tube (500) is removed, and the process of sealing one end of the gas discharge tube (300) may be the same as in Example 3 of the present invention. In addition, in Example 4, similarly to Example 3, the electrolyte injection process is performed after the pouch sealing process, so that the edge of the pouch (200) is sealed before the pouch (200) is immersed in the electrolyte, and thus the sealing quality may be improved.

[0117] Although the present invention has been described above with reference to limited embodiments and drawings, the present invention is not limited thereto, and various embodiments are possible within the scope of the technical idea of ​​the present invention and the equivalent scope of the claims to be described below by a person having ordinary skill in the art to which the present invention pertains.

[0118] [Explanation of symbols]

[0119] 10, 10', 10'': Pouch cell

[0120] 100: Electrode assembly

[0121] 200: Pouch

[0122] 210: Cup

[0123] 220: Terrace

[0124] 300, 300': Gas discharge pipe

[0125] 300-1: First gas discharge pipe

[0126] 300-2: Second gas discharge pipe

[0127] 301: Inner layer

[0128] 302: Transmittance layer

[0129] 303: Outer layer

[0130] 310: Seal

[0131] 320: Passageway

[0132] 400: Electrode lead

[0133] 500: Mishilling Hall

Claims

1. Electrode assembly; A pouch containing an electrode assembly therein; and It includes a gas discharge pipe that is arranged to extend from the inside to the outside of the pouch, A pouch cell in which gas inside the pouch passes through the gas discharge tube and is discharged outside the pouch.

2. In paragraph 1, The above gas discharge pipe, Inner and outer layers having heat sealing properties; and A pouch cell comprising a permeable layer disposed between the inner layer and the outer layer and having higher gas permeability than the inner layer and the outer layer.

3. In paragraph 2, The inner and outer layers above are, Contains polyolefin resin, The above-mentioned permeable layer is, A pouch cell containing PTFE (Polytetrafluoroethylene).

4. In paragraph 1, The above gas discharge pipe, A pouch cell further comprising a sealing portion protruding from the outside of the pouch and having an inner layer sealed by a sealant.

5. In paragraph 4, The above gas discharge pipe, A pouch cell further comprising a passage extending from the sealing portion to the inside of the pouch and communicating with the inside of the pouch to form a space through which gas can move.

6. In paragraph 5, The outer layer of the above passage is a pouch cell sealed by the pouch and sealing.

7. In paragraph 1, Further comprising an electrode lead electrically connected to the electrode assembly and extending to the outside of the pouch; The above gas discharge pipe, A pouch cell arranged with a gap between the electrode leads.

8. In paragraph 1, The above pouch is, A cup portion having a space provided therein in which the electrode assembly is placed; and It includes a terrace part that is arranged on the edge of the cup part and sealed, The above gas discharge pipe, A pouch cell arranged in a form fitted into the above terrace section.

9. In paragraph 1, The above gas discharge pipe, A first gas discharge pipe arranged at one end of the length of the above pouch; and A pouch cell comprising a second gas discharge tube arranged at the longitudinal end of the pouch.

10. In paragraph 9, The above first gas discharge pipe is arranged eccentrically on one side of the width direction of the pouch, A pouch cell in which the second gas discharge pipe is arranged eccentrically on the other side in the width direction of the pouch. 11.(S1) A step of arranging a gas discharge tube on the edge of a pouch containing an electrode assembly therein; (S2) A step of inserting a non-sealing tube configured to prevent sealing of the gas discharge tube into the inside of the gas discharge tube; (S3) a step of sealing the edge of the pouch; and (S4) A method for manufacturing a pouch cell, comprising a step of injecting an electrolyte into the interior of the pouch through the gas discharge pipe.

12. In paragraph 11, The above gas discharge pipe, A first gas discharge pipe arranged at one end of the length of the above pouch; and Including a second gas discharge pipe arranged at the longitudinal end of the above pouch, In the above step (S4), An electrolyte is injected into the pouch through the first gas discharge pipe, A method for manufacturing a pouch cell, wherein gas inside the pouch is removed through the second gas discharge pipe.

13. In paragraph 11, (S5) A step of removing the non-sealing tube after injecting the electrolyte into the pouch; and (S6) A method for manufacturing a pouch cell, further comprising a step of sealing one end of the gas discharge pipe.

14. A method for manufacturing a pouch cell in accordance with claim 11, wherein the non-sealing tube comprises a fluorine-based resin having no sealing properties. 15.(S1') A step of combining the unsealed pipe and the gas discharge pipe so that the outer surface of the unsealed pipe and the inner surface of the gas discharge pipe face each other; (S2') A step of arranging the gas discharge tube coupled to the sealing tube on the edge of a pouch containing the electrode assembly therein; (S3') a step of sealing the edge of the pouch; and (S4') A method for manufacturing a pouch cell, comprising a step of injecting an electrolyte into the interior of the pouch through the non-sealing tube.

16. In paragraph 15, (S5') A step of removing the non-sealing tube after injecting the electrolyte into the pouch; and (S6') A method for manufacturing a pouch cell, further comprising the step of sealing one end of the gas discharge pipe.

17. A method for manufacturing a pouch cell in accordance with claim 15, wherein the non-sealing tube comprises a fluorine-based resin having no sealing properties.

18. A method for manufacturing a pouch cell in which the sealing strength of one end of the sealed discharge tube is set to be weaker than the sealing strength of the pouch rim in the 16th paragraph.

Images