Pouch Cell

Abstract

The present invention relates to a pouch cell that can improve the sealing durability of a joined portion so as to delay or prevent the occurrence of a pouch venting phenomenon caused by internal gas generated during charging or discharging of the pouch cell. The pouch cell according to the present invention may include an electrode assembly, an inner pouch film that covers a portion of the electrode assembly, and an outer pouch film that surrounds an outer edge of the inner pouch film and is attached to the inner pouch film so as to cover the outer surface of the electrode assembly together with the inner pouch film.

Description

[Technical Field]

[0001] This application claims the benefit of priority based on Korean Patent Application No. 10-2022-0171497, filed December 9, 2022, Korean Patent Application No. 10-2023-0044304, filed April 4, 2023, and Korean Patent Application No. 10-2023-0174817, filed December 5, 2023, the entire contents of which are incorporated herein by reference.

[0002] The present invention relates to a pouch cell, and more particularly to a secondary battery pouch cell that can be charged and discharged. [Background technology]

[0003] In recent years, as the cost of energy sources has risen due to the depletion of fossil fuels and concerns about environmental pollution have grown, the need for environmentally friendly alternative energy sources has become an essential factor for future life. Therefore, research into various electricity production technologies, such as solar, wind, and tidal power, has continued, and there has also been great interest in power storage devices such as batteries to more efficiently use the electrical energy produced in this way.

[0004] Furthermore, with the increasing technological development and demand for battery-based electronic mobile devices and electric vehicles, the demand for batteries as an energy source is increasing rapidly, and as a result, much research is being done on batteries that can meet various needs.

[0005] Batteries that store electrical energy can generally be divided into primary batteries and secondary batteries. While primary batteries are disposable, secondary batteries are rechargeable batteries manufactured using materials that allow for repeated oxidation and reduction processes between electric current and materials. In other words, when a reduction reaction occurs in a material due to electric current, the power source is charged, and when an oxidation reaction occurs in the material, the power source is discharged. Electricity is generated through repeated charge-discharge cycles.

[0006] Secondary batteries are classified into cylindrical cells, pouch cells, prismatic cells, etc., depending on their shape. Among them, pouch cells may be manufactured by housing an electrode assembly in which a positive electrode, a negative electrode, a separator, etc. are stacked inside a pouch, and sealing the outside of the pouch.

[0007] Meanwhile, the pouch of a pouch cell may contain an electrolyte solution along with an electrode assembly. Residual moisture in the electrolyte solution or moisture that has penetrated from the outside may react with the lithium salt inside the pouch 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 solution. Furthermore, depending on the positive electrode material contained in the electrode assembly of the pouch cell, additional hydrogen and HF may be generated, which may lead to overheating due to overcharging and internal short circuits during charging and discharging. This may result in the generation of a large amount of gas inside the pouch. This gas increases the pressure inside the pouch, which may cause the pouch to expand (swelling) or partially rupture (venting).

[0008] FIG. 1 is a cross-sectional view that schematically illustrates a cross section of a conventional pouch cell.

[0009] 1, a conventional pouch cell may be formed by bonding a pair of pouch films facing each other. Specifically, an electrode assembly including a negative electrode, a positive electrode, and a separator is disposed in the cup portions of the pair of facing pouch films, and electrode leads electrically connected to the electrode assembly may protrude outside the pouch films.

[0010] In addition, in a conventional pouch cell, a pair of pouch films each have a sealant layer on one side thereof that faces each other, and thus the pair of pouch films can be bonded to each other as the sealant layers facing each other melt due to heat.

[0011] In conventional pouch cells, stress caused by gas generated inside the pouch is concentrated at the temporary seal area. Here, the temporary seal area may refer to a portion formed from the inner edge of the sealed portion to a specific point inside. Specifically, it may refer to a portion where the pouch is relatively weakly adhered by an adhesive material compared to the sealed portion. Therefore, in conventional pouch cells, stress may be concentrated at the temporary seal area, which has relatively weak adhesive sealing. In other words, conventional pouch cells have a problem in that the seal of the sealed portion is easily damaged by pressure from internal gas. Furthermore, due to such damage, conventional pouch cells have a high risk of venting.

[0012] Therefore, there is a need for a new type of pouch cell that can improve the sealing durability in order to delay or prevent the occurrence of the venting phenomenon. Summary of the Invention [Problem to be solved by the invention]

[0013] An object of the present invention is to provide a pouch cell that can improve the sealing durability of the joined parts so as to delay or prevent the occurrence of a pouch venting phenomenon caused by internal gas generated during the charging or discharging process of the pouch cell. [Means for solving the problem]

[0014] The pouch cell according to the present invention may include an electrode assembly, an inner pouch film that covers a portion of the electrode assembly, and an outer pouch film that surrounds an outer edge of the inner pouch film and is attached to the inner pouch film so as to cover the outer surface of the electrode assembly together with the inner pouch film.

[0015] The inner pouch film may include a 1-1 layer and a 1-2 layer disposed on the opposite side of the electrode assembly relative to the 1-1 layer, and the outer pouch film may include a 2-1 layer facing the electrode assembly and bonded to the 1-2 layer so that the inner pouch film and the outer pouch film are bonded to each other.

[0016] The inner pouch film includes an inner main body portion and an inner peripheral portion connected to the inner main body portion at a predetermined angle and extending toward the outer pouch film, and the outer pouch film includes an outer main body portion and an outer peripheral portion connected to the outer main body portion at a predetermined angle and extending toward the inner pouch film, and the outer edge of the inner peripheral portion and the inner edge of the outer peripheral portion can contact each other and be joined.

[0017] The pouch cell may further include an electrode lead electrically connecting the electrode assembly to the outside, wherein a first through hole is formed in the inner peripheral portion and a second through hole is formed in the outer peripheral portion at a position corresponding to the position of the first through hole, and the electrode lead may be electrically connected to the outside via the first through hole and the second through hole.

[0018] The inner peripheral portion may extend such that one end contacts the outer main body portion.

[0019] The outer periphery may extend the same length as the inner periphery.

[0020] The outer pouch film includes an outer main body portion, an outer peripheral edge portion connected to the outer main body portion at a predetermined angle and extending toward the inner pouch film, and a joining portion connected to the outer peripheral edge portion at a predetermined angle and extending in a direction away from the outer peripheral edge portion, and the outer edge of the inner pouch film and the inner edge of the joining portion can come into contact with each other and be joined.

[0021] The inner pouch film includes an inner main body portion and an inner peripheral portion connected to the inner main body portion at a predetermined angle and extending toward the outer pouch film, and the outer edge of the inner main body portion and the inner edge of the connecting portion can contact and be connected to each other, and the outer edge of the inner peripheral portion and the inner edge of the outer peripheral portion can contact and be connected to each other.

[0022] At least one of the 1-2 layer and the 2-1 layer may contain a polyolefin resin.

[0023] The polyolefin resin may be PP (Polypropylene) or PE (Polyethylene).

[0024] The outer pouch film may include a 2-2 layer disposed on the opposite side of the electrode assembly relative to the 2-1 layer, and at least one of the 1-1 layer and the 2-2 layer may include aluminum (Al) or stainless steel (SUS).

[0025] The outer pouch film may further include an insulating layer including an insulating material and disposed on the opposite side of the electrode assembly with respect to the 2-2 layer.

[0026] The inner pouch film may further include a corrosion-resistant layer including a corrosion-resistant material and disposed between the first layer and the electrode assembly.

[0027] The 1-1 layer may include a metal, and the 1-2 layer may include a polyolefin resin.

[0028] The inner pouch film and the outer pouch film have a box shape with one side open, and the outer surface of the peripheral portion formed along the corner of one side of the inner pouch film can be connected to the inner surface of the peripheral portion formed along the corner of one side of the outer pouch film. [Effects of the Invention]

[0029] The pouch cell according to the present invention may include an electrode assembly, an inner pouch film covering the electrode assembly, and an outer pouch film surrounding an outer edge of the inner pouch film and coupled to the inner pouch film.

[0030] This can delay or prevent the venting phenomenon of the pouch caused by internal gas generated during charging or discharging of the pouch cell.

[0031] In addition, stress caused by gas generated inside the pouch is dispersed, and the occurrence of venting of the pouch can be delayed or prevented.

[0032] Furthermore, by improving the sealing durability of the joined portion, the safety of the pouch cell can be improved.

[0033] Furthermore, stress caused by gas generated inside the pouch acts in the planar direction of the bonded portion, thereby achieving the effect of improving the bondability.

[0034] The effects of the present invention are not limited to the above-mentioned examples, and various other effects are included within the present specification. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a cross-sectional view schematically illustrating a cross section of a conventional pouch cell. [Figure 2] 1 is a perspective view schematically illustrating a pouch cell according to an embodiment of the present invention; [Figure 3] 1 is a perspective view schematically illustrating an inner pouch film and an outer pouch film according to an embodiment of the present invention. [Figure 4] 3 is a cross-sectional view schematically illustrating a part of a cross section of a pouch cell according to an embodiment of the present invention taken along line AA' of FIG. 2. [Figure 5] 3 is a cross-sectional view schematically illustrating a part of a cross section of a pouch cell according to another embodiment of the present invention taken along line AA' of FIG. 2. FIG. [Figure 6] 3 is a cross-sectional view schematically illustrating a portion of a cross section of a pouch cell according to yet another embodiment of the present invention taken along line AA' of FIG. 2. FIG. [Figure 7] 3 is a cross-sectional view schematically illustrating a portion of a cross section of a pouch cell according to yet another embodiment of the present invention taken along line AA' of FIG. 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0036] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention will now be described in detail with reference to the accompanying drawings, in order to enable those skilled in the art to easily carry out the present invention. However, the present invention may be embodied in various different forms and should not be construed as being limited to the following embodiments.

[0037] In order to clearly explain the present invention, detailed descriptions of parts that are not relevant to the explanation or related known technologies that may obscure the gist of the present invention are omitted. In this specification, when referring to components in each drawing, the same or similar reference numerals are used throughout the specification to refer to the same or similar components.

[0038] Furthermore, the terms and words used in this specification and claims should not be interpreted in a limited way to their ordinary or dictionary meanings, but should be interpreted in a way that is consistent with the technical idea of ​​the present invention, in accordance with the principle that inventors can appropriately define the concepts of terms in order to best explain their inventions.

[0039] FIG. 2 is a perspective view schematically illustrating a pouch cell 10 according to one embodiment of the present invention, and FIG. 3 is a perspective view schematically illustrating an inner pouch film 100 and an outer pouch film 200 according to one embodiment of the present invention.

[0040] The pouch cell 10 according to one embodiment of the present invention may include an electrode assembly, an inner pouch film 100, and an outer pouch film 200. Here, 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 having an electrode assembly including a negative electrode, a positive electrode, and a separator disposed inside a pouch, with the pouch enclosing the electrode assembly. Conventional pouch cells may include a pouch formed by molding a cup portion into a pouch film that can accommodate the electrode assembly. Meanwhile, the pouch cell 10 according to one embodiment of the present invention may include a pouch with a different shape than conventional pouches.

[0041] The inner pouch film 100 of the pouch cell 10 according to one embodiment of the present invention can cover a portion of the electrode assembly. Specifically, the inner pouch film 100 and the outer pouch film 200 can cover the outer surface of the electrode assembly. That is, the outer pouch film 200 can cover a portion of the outer surface of the electrode assembly that the inner pouch film 100 cannot cover. Hereinafter, the state in which the inner pouch film 100 and the outer pouch film 200 are combined is defined as a pouch.

[0042] 2 and 3, the inner pouch film 100 and the outer pouch film 200 covering the electrode assembly may be disposed in a bonded state. With regard to the bonded form of the inner pouch film 100 and the outer pouch film 200, the outer pouch film 200 of the pouch cell 10 according to one embodiment of the present invention may be bonded to the inner pouch film 100 while surrounding the outer edge of the inner pouch film 100. That is, while conventional pouch films are bonded by contacting opposing surfaces, the inner pouch film 100 and the outer pouch film 200 according to one embodiment of the present invention may be bonded by contacting the outer surface of the inner pouch film 100 and the inner surface of the outer pouch film 200.

[0043] The shapes of the inner pouch film 100 and the outer pouch film 200 according to one embodiment of the present invention will be described in more detail below.

[0044] Referring to Fig. 3, the inner pouch film 100 and the outer pouch film 200 may have a box shape. Here, the box shape may refer to a substantially rectangular parallelepiped shape. Specifically, the inner pouch film 100 and the outer pouch film 200 may have a box shape with one side open. With reference to Fig. 3, the open side of the inner pouch film 100 may be the upper side, and the open side of the outer pouch film 200 may be the lower side.

[0045] A portion of the inner pouch film 100 can enter the inside of the outer pouch film 200 through the open side of the outer pouch film 200. Here, the outer surface of the peripheral portion formed along the corner of one side of the inner pouch film 100 can be joined to the inner surface of the peripheral portion formed along the corner of one side of the outer pouch film 200. That is, the inner pouch film 100 and the outer pouch film 200 can be joined in a form in which two boxes with one open side fit together (see FIG. 2). When the inner pouch film 100 and the outer pouch film 200 have a rectangular parallelepiped shape, the peripheral portion can refer to the four side surfaces.

[0046] An electrode assembly can be accommodated in a space formed inside by combining the inner pouch film 100 and the outer pouch film 200.

[0047] Hereinafter, the manner in which the inner pouch film 100 and the outer pouch film 200 are combined according to one embodiment of the present invention will be described in more detail.

[0048] FIG. 4 is a cross-sectional view schematically illustrating a part of a cross section of the pouch cell 10 according to one embodiment of the present invention taken along line AA' of FIG.

[0049] 4, the inner pouch film 100 of the pouch cell 10 may include a 1-1 layer 101 and a 1-2 layer 102. Here, the 1-2 layer 102 may be disposed on the opposite side of the electrode assembly with respect to the 1-1 layer 101. That is, the 1-1 layer 101 may be disposed closer to the electrode assembly than the 1-2 layer 102.

[0050] The outer pouch film 200 of the pouch cell 10 may include a 2-1 layer 201. The 2-1 layer 201 of the outer pouch film 200 may face the electrode assembly. Here, the 2-1 layer 201 of the outer pouch film 200 may be bonded to the 1-2 layer 102 of the inner pouch film 100 so that the inner pouch film 100 and the outer pouch film 200 are bonded to each other. Specifically, a portion of the 2-1 layer 201 of the outer pouch film 200 may be bonded to a portion of the 1-2 layer 102 of the inner pouch film 100.

[0051] In the pouch cell 10 according to one embodiment of the present invention, the first-2 layer 102 including the outer surface of the inner pouch film 100 and the second-1 layer 201 including the inner surface of the outer pouch film 200 can be bonded together by contacting each other. Therefore, stress due to gas generated inside the pouch cell 10 can act in the plane direction of the inner pouch film 100 or the outer pouch film 200. In other words, the pouch cell 10 according to one embodiment of the present invention, in which stress acts in a different manner than conventional pouch cells, can have improved resistance to pressure inside the pouch cell. In addition, the pouch cell 10 according to one embodiment of the present invention can be manufactured in a substantially rectangular parallelepiped shape.

[0052] Meanwhile, there may be various ways to join a portion of the 1-2 layer 102 and a portion of the 2-1 layer 201. For example, a portion of the 1-2 layer 102 and a portion of the 2-1 layer 201 may be joined by sealing with the application of heat and pressure.

[0053] As an example of a structure that can be bonded by heat and pressure, the first-2 layer 102 and the second-1 layer 201 may include a polyolefin-based resin. More specifically, the first-2 layer 102 and the second-1 layer 201 may include 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, polyparaphenylene benzobisoxazole, polyarylate, Teflon, and glass fiber. Polyolefin-based resins such as polypropylene (PP) or polyethylene (PE) are typically used. Polypropylene, in particular, offers excellent mechanical properties, such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, as well as excellent chemical properties, such as corrosion resistance.

[0054] The 1-2 layer 102 and the 2-1 layer 201 contain polyolefin resin, which is an example of a material having heat-sealing properties, and can be bonded to each other by melting the polyolefin resin with heat.

[0055] The inner pouch film 100 and the outer pouch film 200 according to one embodiment of the present invention may include other layers in addition to the layer containing a polyolefin-based resin. For example, the inner pouch film 100 and the outer pouch film 200 may include a layer containing a metal.

[0056] In this regard, the outer pouch film 200 may include a 2-2 layer 202 disposed on the opposite side of the electrode assembly with respect to the 2-1 layer 201. That is, the outer pouch film 200 may include the 2-1 layer 201 positioned close to the electrode assembly disposed therein, and the 2-2 layer 202 positioned farther from the electrode assembly than the 2-1 layer 201.

[0057] Here, at least one of the 1-1 layer 101 of the inner pouch film 100 and the 2-2 layer 202 of the outer pouch film 200 can contain aluminum (Al) or stainless steel (SUS). Specifically, the 1-1 layer 101 and the 2-2 layer 202 can contain aluminum (Al) or stainless steel (SUS). Preferably, to ensure the rigidity of the inner pouch film 100 and the outer pouch film 200, the 1-1 layer 101 and the 2-2 layer 202 can contain stainless steel (SUS).

[0058] Meanwhile, as another example, the 1-1 layer 101 and the 2-2 layer 202 may further include one or more materials selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), and nickel (Ni). Since the 1-1 layer 101 of the inner pouch film 100 and the 2-2 layer 202 of the outer pouch film 200 contain metal, the pouch cell 10 can ensure rigidity.

[0059] 4, an inner pouch film 100 according to one embodiment of the present invention may include an inner main body portion 110 and an inner peripheral portion 120. Here, the inner peripheral portion 120 may be connected to the inner main body portion 110 so as to form a predetermined angle. Also, the inner peripheral portion 120 may extend toward the outer pouch film 200. Preferably, the angle formed between the inner main body portion 110 and the inner peripheral portion 120 may be approximately 90 degrees.

[0060] The outer pouch film 200 may include an outer main body portion 210 and an outer peripheral portion 220. Here, the outer peripheral portion 220 may be connected to the outer main body portion 210 so as to form a predetermined angle therewith. Also, the outer peripheral portion 220 may extend toward the inner pouch film 100. Preferably, the angle formed between the outer main body portion 210 and the outer peripheral portion 220 may be approximately 90 degrees.

[0061] The inner body portion 110 of the inner pouch film 100 and the outer body portion 210 of the outer pouch film 200 may have a plate shape with a substantially rectangular cross section and can cover the top and bottom of the electrode assembly. In addition, the inner peripheral portion 120 and the outer peripheral portion 220 are connected to the four corners of the inner body portion 110 and the outer body portion 120, which have a substantially rectangular cross section, and can cover the sides of the electrode assembly.

[0062] 4, the outer edge of the inner peripheral portion 120 and the inner edge of the outer peripheral portion 220 may contact and be bonded to each other. Specifically, the first-second layer 102 of the inner peripheral portion 120 and the second-first layer 201 of the outer peripheral portion 220 may contact and be bonded to each other. Here, the first-second layer 102 is a portion obtained by dividing the inner pouch film 100, which is formed of multiple layers, and the inner peripheral portion 120 is a portion obtained by dividing the inner pouch film 100 at a position where it is formed, and the inner peripheral portion 120 may also include the first-second layer 102. Similarly, the outer peripheral portion 220 may also include the second-first layer 201.

[0063] Meanwhile, the electrode assembly, which is covered by and housed between the inner pouch film 100 and the outer pouch film 200, can generate electrical energy. As an example of a configuration for transmitting the electrical energy generated by the electrode assembly to the outside, the pouch cell 10 can include an electrode lead 300 electrically connected to the electrode assembly (see FIG. 2).

[0064] The electrode lead 300 may be a conductor and may have various forms. For example, the electrode lead 300 may have a form that protrudes outside the pouch and may have an outer surface that is positioned flush with the outer surface of the pouch. Alternatively, the outer surface of the electrode lead 300 may be positioned more inward than the outer surface of the pouch.

[0065] As an example of a configuration in which the electrode lead 300 may be disposed, a first through hole 121 may be formed in the inner peripheral portion 120 according to an embodiment of the present invention. Also, a second through hole 221 may be formed in the outer peripheral portion 220. Here, the second through hole 221 in the outer peripheral portion 220 may be formed at a position corresponding to the position where the first through hole 121 in the inner peripheral portion 120 is formed (see FIGS. 1 and 2).

[0066] The shapes of the first through hole 121 and the second through hole 221 may vary depending on the shape of the electrode lead 300. As an example, the pouch cell 10 may include an electrode lead 300 having a substantially rectangular parallelepiped shape, and the first through hole 121 and the second through hole 221 may be formed to have a substantially rectangular cross section.

[0067] When the electrode lead 300 has a shape that protrudes outside the pouch or has an outer surface that is positioned in the same plane as the outer surface of the pouch, the electrode lead 300 can pass through the first through hole 121 and the second through hole 221.

[0068] The electrode lead 300 can be electrically connected to the outside through the first through-hole 121 and the second through-hole 221 .

[0069] The pouch cell 10 may be repeatedly charged and discharged, which may generate gas inside the pouch. According to one embodiment of the present invention, the pressure generated by the gas inside the pouch may act toward each inner surface of the inner pouch film 100. Here, the pressure inside the pouch may also act toward the sides formed along the four corners of the open side of the inner pouch film 100. That is, the pressure generated by the gas inside the pouch may act in a direction that strengthens the adhesive strength between the inner pouch film 100 and the outer pouch film 200. Furthermore, the pressure generated by the gas inside the pouch may act in a planar direction toward the bonded portion between the inner pouch film 100 and the outer pouch film 200. Therefore, the pouch cell 10 including the novel pouch may have improved sealing durability, preventing venting even under relatively high pressure.

[0070] In the following, a description of the same components as those of the pouch cell 10 according to one embodiment of the present invention will be omitted, and the different components will be mainly described.

[0071] FIG. 5 is a cross-sectional view schematically illustrating a part of a cross section of a pouch cell 10 according to another embodiment of the present invention taken along line AA' of FIG.

[0072] In the pouch cell 10 according to another embodiment of the present invention, the shape of the inner peripheral edge portion 120 of the inner pouch film 100 may be different from that of the first embodiment. In addition, the inner pouch film 100 and the outer pouch film 200 may further include other layers.

[0073] 5, according to another embodiment of the present invention, the inner peripheral portion 120 of the inner pouch film 100 may have one end in contact with the outer pouch film 200. Specifically, the inner peripheral portion 120 of the inner pouch film 100 may extend such that one end contacts the outer main body portion 210 of the outer pouch film 200.

[0074] When one end of the inner peripheral portion 120 extends to contact the outer main body portion 210, pressure from the gas inside the pouch can act substantially in the planar direction on the inner peripheral portion 120. Therefore, pressure can act in a direction that improves the sealing durability between the inner peripheral portion 120 and the outer peripheral portion 210.

[0075] Meanwhile, the outer peripheral portion 220 of the outer pouch film 200 may also extend. Preferably, the outer peripheral portion 220 of the outer pouch film 200 may extend by a length L similar to the length of the inner peripheral portion 120 of the inner pouch film 100. Referring to Fig. 5, the length L of the outer peripheral portion 220 may be approximately the same as the length of the inner peripheral portion 120. This increases the area where the inner peripheral portion 120 and the outer peripheral portion 220 are bonded, thereby improving the bonding strength between the inner pouch film 100 and the outer pouch film 200.

[0076] The inner pouch film 100 of the pouch cell 10 according to another embodiment of the present invention may further include other layers in addition to the 1-1 layer 101 and the 1-2 layer 102. Specifically, the inner pouch film 100 may further include a corrosion-resistant layer 103.

[0077] The corrosion-resistant layer 103 of the inner pouch film 100 may include a corrosion-resistant material. Here, the corrosion-resistant material may refer to a material that has resistance to corrosion so as not to be corroded by the electrolyte placed inside the pouch.

[0078] 5, the corrosion-resistant layer 103 of the inner pouch film 100 may be disposed between the 1-1 layer 101 and the electrode assembly. That is, in the inner pouch film 100 according to another embodiment of the present invention, the corrosion-resistant layer 103 may be the layer disposed on the innermost surface, and may be disposed to face the electrode assembly. Therefore, the inner pouch film 100 may be formed in the order of the corrosion-resistant layer 103, the 1-1 layer 101, and the 1-2 layer 102 from the inner surface.

[0079] The inner pouch film 100 of the pouch cell 10 according to another embodiment of the present invention further includes the corrosion-resistant layer 103, thereby preventing corrosion of the 1-1 layer 101 containing metal.

[0080] The outer pouch film 200 of the pouch cell 10 according to another embodiment of the present invention may further include other layers in addition to the 2-1 layer 201 and the 2-2 layer 202. Specifically, the outer pouch film 200 may further include an insulating layer 203.

[0081] The insulating layer 203 of the outer pouch film 200 may include an insulating material, which may mean a material that does not conduct electricity or heat.

[0082] For example, the insulating layer 203 may include 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, polyparaphenylene benzobisoxazole, polyarylate, Teflon (registered trademark), and glass fiber. Polymers such as nylon resin or polyethylene terephthalate (PET), which are abrasion-resistant and heat-resistant, may be used.

[0083] 5, the insulating layer 203 of the outer pouch film 200 may be disposed on the opposite side of the electrode assembly with respect to the 2-2 layer 202. That is, in the outer pouch film 200 according to another embodiment of the present invention, the insulating layer 203 may be the layer disposed on the outermost surface. Therefore, the outer pouch film 200 may be formed in the order of the 2-1 layer 201, the 2-2 layer 202, and the insulating layer 203 from the inner surface.

[0084] The outer pouch film 200 of the pouch cell 10 according to another embodiment of the present invention further includes an insulating layer 203, which can insulate the metal-containing second-second layer 202 from other components. Therefore, the insulating layer 203 can prevent unnecessary short circuits from occurring in the outer pouch film 200.

[0085] FIG. 6 is a cross-sectional view schematically illustrating a part of a cross section of a pouch cell 10 according to still another embodiment of the present invention taken along line AA' of FIG.

[0086] Referring to FIG. 6, the outer pouch film 200 of the pouch cell 10 according to yet another embodiment of the present invention may further include a bonding portion 230.

[0087] The connecting portion 230 of the outer pouch film 200 may be connected to the outer peripheral edge portion 220 at a predetermined angle and may extend in a direction away from the outer peripheral edge portion 220. Specifically, the connecting portion 230 may extend toward the center of the pouch. Here, the angle formed between the outer peripheral edge portion 220 and the connecting portion 230 may be approximately 90 degrees.

[0088] The connecting portion 230 extending away from the outer peripheral portion 220 may be joined to the inner pouch film 100. In this regard, the inner pouch film 100 according to another embodiment of the present invention may have a substantially plate shape. Here, the connecting portion 230 may be joined to the bottom surface of the inner pouch film 100, with reference to FIG. 6 .

[0089] Since the bonding portion 230 is bonded to the underside of the inner pouch film 100, a larger area of ​​the outer pouch film 200 can be bonded to the inner pouch film 100, thereby improving the sealing durability of the pouch cell 10.

[0090] In the following, a description of the same configuration as that of the pouch cell 10 according to one embodiment of the present invention and other embodiments will be omitted, and different configurations will be mainly described.

[0091] FIG. 7 is a cross-sectional view schematically illustrating a part of a cross section of a pouch cell 10 according to still another embodiment of the present invention taken along line AA' of FIG.

[0092] Referring to FIG. 7, when the outer pouch film 200 includes the connecting portion 230, the inner pouch film 100 may include the inner main body portion 110 and the inner peripheral portion 120.

[0093] Specifically, the inner pouch film 100 and the outer pouch film 200 can be joined by contacting the outer edge of the inner main body portion 110 and the inner edge of the joining portion 230, and by contacting the outer edge of the inner peripheral portion 120 and the inner edge of the outer peripheral portion 220. Here, the inner peripheral portion 120 of the inner pouch film 100 can also extend so as to contact the outer main body portion 210 of the outer pouch film 200.

[0094] 7, a pouch cell 10 according to another embodiment of the present invention may be joined at two portions, thereby further improving the sealing performance between the inner pouch film 100 and the outer pouch film 200. Here, both of the joined portions can receive pressure from the inside of the pouch in the planar direction.

[0095] The present invention has been described above using limited embodiments and drawings, but the present invention is not limited thereto, and various implementations are possible within the technical spirit of the present invention and the scope of the claims set forth below by a person having ordinary skill in the art to which the present invention pertains. [Explanation of symbols]

[0096] 10 pouch cells 100 Inner pouch film 101 1st-1st layer 102 1st-2nd layer 103 Corrosion-resistant layer 110 Inner body part 120 Inner periphery 121 First through hole 200 outer pouch film 201 2nd-1st layer 202 2nd-2nd layer 203 Insulating layer 210 outer body 220 outer periphery 221 Second through hole 230 Joint 300 electrode leads

Claims

1. an electrode assembly; an inner pouch film that covers a portion of the electrode assembly; an outer pouch film that is connected to the inner pouch film while surrounding an outer edge of the inner pouch film so as to cover the outer surface of the electrode assembly together with the inner pouch film.

2. The inner pouch film is a first layer and a second layer disposed on the opposite side of the electrode assembly with respect to the first layer, The outer pouch film is The pouch cell of claim 1, further comprising a second-first layer facing the electrode assembly and bonded to the first-second layer so as to bond the inner pouch film and the outer pouch film.

3. The inner pouch film is an inner main body portion; an inner peripheral portion connected to the inner main body portion at a predetermined angle and extending toward the outer pouch film; The outer pouch film is an outer main body portion; an outer peripheral portion connected to the outer main body portion at a predetermined angle and extending toward the inner pouch film; The pouch cell of claim 1 , wherein an outer edge of the inner periphery and an inner edge of the outer periphery are in contact with each other and bonded together.

4. further comprising an electrode lead electrically connecting the electrode assembly to the outside, A first through hole is formed in the inner peripheral edge portion, a second through hole is formed in the outer peripheral edge portion at a position corresponding to the position of the first through hole; The pouch cell of claim 3 , wherein the electrode lead is electrically connected to the outside through the first through-hole and the second through-hole.

5. The inner peripheral portion is The pouch cell of claim 3 , wherein one end extends into contact with the outer body portion.

6. The outer peripheral portion is 6. The pouch cell of claim 5, wherein the inner periphery extends the same length as the inner periphery extends.

7. The outer pouch film is an outer main body portion; an outer peripheral edge portion connected to the outer main body portion at a predetermined angle and extending toward the inner pouch film; a connecting portion connected to the outer peripheral edge portion at a predetermined angle and extending in a direction away from the outer peripheral edge portion, The pouch cell according to claim 1 , wherein an outer edge of the inner pouch film and an inner edge of the joint portion are joined together by contacting each other.

8. The inner pouch film is an inner main body portion; an inner peripheral portion connected to the inner main body portion at a predetermined angle and extending toward the outer pouch film; The outer edge of the inner body portion and the inner edge of the connecting portion are in contact with each other and connected to each other, The pouch cell of claim 7 , wherein an outer edge of the inner periphery and an inner edge of the outer periphery contact and bond with each other.

9. At least one of the first-2 layer and the second-1 layer is The pouch cell according to claim 2 , comprising a polyolefin-based resin.

10. The polyolefin resin is The pouch cell according to claim 9, which is made of PP (Polypropylene) or PE (Polyethylene).

11. The outer pouch film is a second-2 layer disposed on the opposite side of the electrode assembly with respect to the second-1 layer; At least one of the 1-1 layer and the 2-2 layer is 3. The pouch cell of claim 2, comprising aluminum (Al) or stainless steel (SUS).

12. The outer pouch film is The pouch cell of claim 11, further comprising an insulating layer including an insulating material and disposed on the opposite side of the electrode assembly with respect to the 2-2 layer.

13. The inner pouch film is The pouch cell of claim 2 , further comprising a corrosion-resistant layer comprising a corrosion-resistant material and disposed between the first-1 layer and the electrode assembly.

14. The 1-1 layer is Contains metal, The first and second layers are The pouch cell of claim 13, comprising a polyolefin-based resin.

15. The inner pouch film and the outer pouch film are It has a box shape with one side open, The pouch cell according to claim 1 , wherein an outer surface of a peripheral edge portion formed along a corner of one surface of the inner pouch film is joined to an inner surface of a peripheral edge portion formed along a corner of one surface of the outer pouch film.

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