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 Nos. 10-2022-0171497 filed on December 9, 2022, 10-2023-0044304 filed on April 4, 2023, and 10-2023-0174817 filed on December 5, 2023, and all the contents disclosed in the Korean patent applications are incorporated herein by reference.

[0002] The present invention relates to a pouch cell, and more particularly, to a secondary battery pouch cell capable of charging and discharging.

Background Art

[0003] In recent years, the value of energy sources has increased due to the depletion of fossil fuels, the concern about environmental pollution has amplified, and the need for environmentally friendly alternative energy sources has become an essential and indispensable factor for future life. Therefore, research on various power generation technologies such as solar power, wind power, and tidal power has continued, 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, as the technology development and demand for electronic mobile devices and electric vehicles using batteries increase, the demand for batteries as an energy source has increased rapidly, and accordingly, many studies on batteries that can meet various needs have been conducted.

[0005] Batteries for storing electrical energy can generally be divided into primary batteries and secondary batteries. Primary batteries are disposable and consumable batteries, 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 is performed on the material by current, the power source is charged, and when an oxidation reaction is performed on the material, the power source discharges, and electricity is generated while such charging and discharging are repeated.

[0006] Rechargeable batteries can be classified into cylindrical cells, pouch cells, prismatic cells, etc., depending on their form. Among these, pouch cells can be manufactured in a form in which an electrode assembly, in which a positive electrode, negative electrode, separator, etc. are stacked, is housed inside a pouch, and the outside of the pouch is sealed.

[0007] On the other hand, the pouch of a pouch cell can contain an electrolyte along with the electrode assembly. Here, remaining water in the electrolyte and water that has seeped in from the outside react with the lithium salt inside the pouch of the pouch cell 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. In addition, depending on the material of the positive electrode contained in the electrode assembly of the pouch cell, hydrogen and HF may be further generated, which can lead to overcharging and overheating due to internal short circuits during the charging and discharging process. Consequently, a large amount of gas may be generated inside the pouch. Such gases can increase the pressure inside the pouch, and this increased pressure can cause swelling, where the pouch expands, or venting, where a part of the pouch ruptures.

[0008] Figure 1 is a schematic cross-sectional view illustrating a cross-section of a conventional pouch cell.

[0009] Referring to Figure 1, a conventional pouch cell can be formed by joining a pair of pouch films facing each other. Specifically, an electrode assembly including a negative electrode, a positive electrode, and a separator is placed in the cup portion of the pair of opposing pouch films, and electrode leads electrically connected to the electrode assembly protrude from the outside of the pouch film.

[0010] Furthermore, conventional pouch cells have a sealant layer on one side of each of the two pouch films that are facing each other. Therefore, the two pouch films can be joined together as the sealant layers on the opposing sides melt due to heat.

[0011] In conventional pouch cells, stress caused by gas generated inside the pouch concentrates at the tack seal. Here, the tack seal can refer to the area formed from the inner edge of the area to be sealed to a specific point inside. Specifically, it can refer to the area where the pouch is relatively weakly bonded by the adhesive compared to the area to be sealed. Therefore, in conventional pouch cells, stress can concentrate at the tack seal where the adhesive seal is relatively weak. In other words, conventional pouch cells had the problem that the seal in the sealed area was easily damaged by the pressure from the gas inside. Furthermore, such damage increased the risk of venting in conventional pouch cells.

[0012] Therefore, there is a need for a new form of pouch cell that can improve sealing durability in order to delay or prevent the occurrence of venting. [Overview of the Initiative] [Problems that the invention aims to solve]

[0013] The object of the present invention is to provide a pouch cell that can improve the sealing durability of the bonded portion so as to delay or prevent the venting phenomenon of the pouch caused by internal gases 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 covering a portion of the electrode assembly, and an outer pouch film that surrounds the outer edge of the inner pouch film and is bonded 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 includes a 1-1 layer and a 1-2 layer positioned on the opposite side of the electrode assembly with respect 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 such that the inner pouch film and the outer pouch film are bonded together.

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

[0017] The pouch cell further includes electrode leads that electrically connect the electrode assembly to the outside, wherein a first through-hole is formed in the inner periphery, and a second through-hole is formed in the outer periphery at a position corresponding to the position of the first through-hole, and the electrode leads can be electrically connected to the outside through the first and second through-holes.

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

[0019] The outer peripheral portion can extend to the same length as the inner peripheral portion.

[0020] The outer pouch film includes an outer body portion, an outer peripheral portion connected to the outer body portion at a predetermined angle and extending toward the inner pouch film, and a connecting portion connected to the outer peripheral portion at a predetermined angle and extending away from the outer peripheral portion, so that the outer edge of the inner pouch film and the inner edge of the connecting portion can contact and connect with each other.

[0021] The inner pouch film includes an inner main body portion and an inner peripheral edge portion that is connected to the inner main body portion at a predetermined angle and extends toward the outer pouch film. The outer edge of the inner main body portion and the inner edge of the coupling portion are in contact with each other and joined, and the outer edge of the inner peripheral edge portion and the inner edge of the outer peripheral edge portion can be in contact with each other and joined.

[0022] At least one of the first-second layer and the second-first layer can contain a polyolefin resin.

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

[0024] The outer pouch film includes a second-second layer disposed on the opposite side of the electrode assembly with respect to the second-first layer. At least one of the first-first layer and the second-second layer can contain aluminum (Al) or stainless steel (SUS).

[0025] The outer pouch film contains an insulating substance and can further include an insulating layer disposed on the opposite side of the electrode assembly with respect to the second-second layer.

[0026] The inner pouch film contains a corrosion-resistant substance and can further include a corrosion-resistant layer disposed between the first-first layer and the electrode assembly.

[0027] The first-first layer contains a metal, and the first-second layer can contain 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 edge portion formed along the corner of one side of the inner pouch film can be joined to the inner surface of the peripheral edge portion formed along the corner of one side of the outer pouch film.

Advantages of the Invention

[0029] The pouch cell according to the present invention can include an electrode assembly, an inner pouch film covering the electrode assembly, and an outer pouch film that surrounds the outer edge of the inner pouch film and is bonded to the inner pouch film.

[0030] Thereby, it is possible to delay or prevent the occurrence of the bending phenomenon of the pouch due to internal gas or the like generated during the charging or discharging process of the pouch cell.

[0031] Also, the stress caused by the gas generated inside the pouch is dispersed, and it is possible to delay or prevent the occurrence of the bending phenomenon of the pouch.

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

[0033] Also, the stress caused by the gas generated inside the pouch acts in the plane direction of the bonded portion, and it is possible to exhibit the effect of improving the bonding property.

[0034] The effects according to 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

[0035] [Figure 1] It is a cross-sectional view schematically showing the cross-section of a conventional pouch cell. [Figure 2] It is a perspective view schematically showing a pouch cell according to an embodiment of the present invention. [Figure 3] It is a perspective view schematically showing an inner pouch film and an outer pouch film according to an embodiment of the present invention. [Figure 4] It is a cross-sectional view schematically showing a part of the cross-section obtained by cutting the pouch cell according to an embodiment of the present invention along A-A' in FIG. 2. [Figure 5] This is a schematic cross-sectional view showing a portion of a cross-section of a pouch cell according to another embodiment of the present invention, cut along line A-A' in Figure 2. [Figure 6] This is a schematic cross-sectional view showing a portion of a cross-section of a pouch cell according to yet another embodiment of the present invention, cut along line A-A' in Figure 2. [Figure 7] This is a schematic cross-sectional view showing a portion of a cross-section of a pouch cell according to yet another embodiment of the present invention, cut along line A-A' in Figure 2. [Modes for carrying out the invention]

[0036] 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.

[0037] In order to clearly explain the present invention, detailed descriptions of related known technologies that are irrelevant to the description or that could obscure the essence 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.

[0038] 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.

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

[0040] A 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 mean a rechargeable and dischargeable secondary battery. Specifically, it may mean a secondary battery in which an electrode assembly including a negative electrode, a positive electrode, and a separator is arranged inside the pouch, and the pouch encloses the electrode assembly. Conventional pouch cells may include a pouch formed by molding a cup portion in the pouch film that can accommodate the electrode assembly. On the other hand, a pouch cell 10 according to one embodiment of the present invention may include a pouch of a different form from the conventional one.

[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 joined together will be defined as a pouch.

[0042] Referring to Figures 2 and 3, the inner pouch film 100 and the outer pouch film 200 covering the electrode assembly can be arranged in a bonded state. In relation to the bonded configuration 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 can be bonded to the inner pouch film 100 while surrounding its outer edge. That is, while conventional pouch films are bonded by contact between opposing surfaces, the inner pouch film 100 and the outer pouch film 200 according to one embodiment of the present invention can be bonded by contact between 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 Figure 3, the inner pouch film 100 and the outer pouch film 200 can have a box shape. Here, the box shape can mean a roughly rectangular parallelepiped shape. Specifically, the inner pouch film 100 and the outer pouch film 200 can have a box shape with one side open. Based on Figure 3, the open side of the inner pouch film 100 can be the top surface, and the open side of the outer pouch film 200 can be the bottom surface.

[0045] A portion of the inner pouch film 100 can enter the interior of the outer pouch film 200 through an open surface of the outer pouch film 200. Here, the outer surface of the peripheral edge formed along the corner of one surface of the inner pouch film 100 can be joined to the inner surface of the peripheral edge formed along the corner of one surface of the outer pouch film 200. That is, the inner pouch film 100 and the outer pouch film 200 can be joined in a manner in which two boxes with one open surface fit together (see Figure 2). If the inner pouch film 100 and the outer pouch film 200 have a rectangular parallelepiped shape, the peripheral edge may mean four sides.

[0046] The electrode assembly can be housed in the space formed inside by the bonding of the inner pouch film 100 and the outer pouch film 200.

[0047] The following describes in more detail the configuration of the inner pouch film 100 and the outer pouch film 200 according to one embodiment of the present invention.

[0048] Figure 4 is a schematic cross-sectional view showing a portion of the cross-section obtained by cutting a pouch cell 10 according to one embodiment of the present invention along line A-A' in Figure 2.

[0049] Referring to Figure 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 positioned 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 positioned 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 second-first layer 201. The second-first layer 201 of the outer pouch film 200 can face the electrode assembly. Here, the second-first layer 201 of the outer pouch film 200 can be bonded to the first-second 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 second-first layer 201 of the outer pouch film 200 can be bonded to a portion of the first-second layer 102 of the inner pouch film 100.

[0051] In one embodiment of the present invention, the pouch cell 10 has a first-to-second layer 102 including the outer surface of the inner pouch film 100 and a second-to-first layer 201 including the inner surface of the outer pouch film 200 that can contact and bond with each other. Therefore, stress caused by gas generated inside the pouch cell 10 can act in the planar 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 in conventional pouch cells, can improve resistance to internal pressure in the pouch cell. Furthermore, the pouch cell 10 according to one embodiment of the present invention can be manufactured in a substantially rectangular parallelepiped shape.

[0052] On the other hand, there can be various methods for joining a portion of the first-second layer 102 and a portion of the second-first layer 201. For example, a portion of the first-second layer 102 and a portion of the second-first layer 201 can be joined by a seal that applies heat and pressure.

[0053] As an example of a structure that can be joined by heat and pressure, the first-second layer 102 and the second-first layer 201 may include polyolefin resins. More specifically, the first-second layer 102 and the second-first layer 201 may include one or more substances 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. Primarily, polyolefin resins such as polypropylene (PP) or polyethylene (PE) can be used. In particular, polypropylene can be excellent in mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, and heat resistance, as well as chemical properties such as corrosion resistance.

[0054] As an example of a material that has heat-sealing properties, the first-to-second layer 102 and the second-to-first layer 201, which contain a polyolefin resin, can be bonded to each other by the melting of the polyolefin resin when heated.

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

[0056] In this regard, the outer pouch film 200 may include a second-second layer 202 positioned on the opposite side of the electrode assembly with respect to the second-first layer 201. That is, the outer pouch film 200 may include a second-first layer 201 positioned close to the electrode assembly located inside, and a second-second layer 202 positioned further away from the electrode assembly than the second-first layer 201.

[0057] Here, at least one of the first-first layer 101 of the inner pouch film 100 and the second-second layer 202 of the outer pouch film 200 may be made of aluminum (Al) or stainless steel (SUS). Specifically, the first-first layer 101 and the second-second layer 202 may be made of aluminum (Al) or stainless steel (SUS). Preferably, in order to ensure the rigidity of the inner pouch film 100 and the outer pouch film 200, the first-first layer 101 and the second-second layer 202 may be made of stainless steel (SUS).

[0058] On the other hand, other examples of the first-first layer 101 and the second-second layer 202 may further include one or more substances selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), and nickel (Ni). Since the first-first layer 101 of the inner pouch film 100 and the second-second layer 202 of the outer pouch film 200 contain metal, the pouch cell 10 can be made rigid.

[0059] Referring to Figure 4, an inner pouch film 100 according to one embodiment of the present invention may include an inner body portion 110 and an inner peripheral portion 120. Here, the inner peripheral portion 120 may be connected to the inner body portion 110 at a predetermined angle. The inner peripheral portion 120 may also extend toward the outer pouch film 200. Preferably, the angle between the inner body portion 110 and the inner peripheral portion 120 may be approximately 90 degrees.

[0060] The outer pouch film 200 may include an outer body portion 210 and an outer peripheral portion 220. Here, the outer peripheral portion 220 may be connected to the outer body portion 210 at a predetermined angle. The outer peripheral portion 220 may also extend toward the inner pouch film 100. Preferably, the angle between the outer 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 can have a plate shape with a substantially rectangular cross-section, and can cover the upper and lower parts 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] Referring to Figure 4, the outer edge of the inner peripheral portion 120 and the inner edge of the outer peripheral portion 220 can contact and join with each other. Specifically, the first and second layers 102 of the inner peripheral portion 120 and the second-first layer 201 of the outer peripheral portion 220 can contact and join with each other. Here, the first and second layers 102 are a part of the inner pouch film 100, which is formed of multiple layers, divided by layers, and the inner peripheral portion 120 is a part of the inner pouch film 100 divided at the position where it is formed, and the inner peripheral portion 120 can also include the first and second layers 102. Similarly, the outer peripheral portion 220 can also include the second-first layer 201.

[0063] On the other hand, the electrode assembly, covered by the inner pouch film 100 and the outer pouch film 200 and housed between them, 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 may include electrode leads 300 that are electrically connected to the electrode assembly (see Figure 2).

[0064] The electrode lead 300 can be a conductor and can have various forms. For example, the electrode lead 300 may have a form that protrudes to the outside of the pouch, or it may have an outer surface that is coplanar with the outer surface of the pouch. Alternatively, the outer surface of the electrode lead 300 may be positioned inside the outer surface of the pouch.

[0065] As an example of a configuration in which electrode leads 300 can be arranged, a first through-hole 121 can be formed in the inner peripheral portion 120 according to one embodiment of the present invention. A second through-hole 221 can also be formed in the outer peripheral portion 220. Here, the second through-hole 221 of the outer peripheral portion 220 can be formed at a position corresponding to the position in which the first through-hole 121 of the inner peripheral portion 120 is formed (see Figures 1 and 2).

[0066] The shapes of the first through-hole 121 and the second through-hole 221 can vary depending on the shape of the electrode lead 300. For example, the pouch cell 10 may include an electrode lead 300 that is substantially rectangular in 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 to the outside of the pouch or has an outer surface that is coplanar with 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 can be repeatedly charged and discharged, which can generate gas inside the pouch. The pressure from the gas inside the pouch according to one embodiment of the present invention can act toward each inner surface of the inner pouch film 100. Here, the pressure inside the pouch can also act toward the sides formed along the four corners of the open surface of the inner pouch film 100. That is, the pressure from the gas inside the pouch can act in a direction that strengthens the adhesion between the inner pouch film 100 and the outer pouch film 200. In addition, the pressure from the gas inside the pouch can act in a planar direction toward the joint between the inner pouch film 100 and the outer pouch film 200. Thus, the pouch cell 10, including the novel form of pouch, can have improved sealing durability so that venting does not occur even under relatively high pressure.

[0070] In the following, we will omit descriptions of configurations that are the same as those of the pouch cell 10 according to one embodiment of the present invention, and will focus on describing the different configurations.

[0071] Figure 5 is a schematic cross-sectional view illustrating a portion of a cross-section obtained by cutting a pouch cell 10 according to another embodiment of the present invention along line A-A' in Figure 2.

[0072] In other embodiments of the present invention, the pouch cell 10 may have a different shape for the inner peripheral edge 120 of the inner pouch film 100 compared to one embodiment. Furthermore, the inner pouch film 100 and the outer pouch film 200 may contain other layers.

[0073] Referring to Figure 5, in another embodiment of the present invention, the inner peripheral edge 120 of the inner pouch film 100 can have one end in contact with the outer pouch film 200. Specifically, the inner peripheral edge 120 of the inner pouch film 100 can extend so that one end is in contact with the outer body 210 of the outer pouch film 200.

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

[0075] On the other hand, the outer peripheral portion 220 of the outer pouch film 200 can also extend. Preferably, the outer peripheral portion 220 of the outer pouch film 200 can extend by a length L similar to the length to which the inner peripheral portion 120 of the inner pouch film 100 extends. Referring to Figure 5, the length L to which the outer peripheral portion 220 extends can be approximately the same as the length to which the inner peripheral portion 120 extends. This increases the area to which the inner peripheral portion 120 and the outer peripheral portion 220 are joined, thereby improving the bonding strength between the inner pouch film 100 and the outer pouch film 200.

[0076] In other embodiments of the present invention, the inner pouch film 100 of the pouch cell 10 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 contain a corrosion-resistant substance. Here, the corrosion-resistant substance may mean a substance that has resistance to corrosion so as not to be corroded by the electrolyte placed inside the pouch.

[0078] Referring to Figure 5, the corrosion-resistant layer 103 of the inner pouch film 100 can be positioned between the 1-1 layer 101 and the electrode assembly. That is, in other embodiments of the present invention, the inner pouch film 100 can have the corrosion-resistant layer 103 as the innermost layer, and the corrosion-resistant layer 103 can be positioned opposite the electrode assembly. Thus, the inner pouch film 100 can be formed in the order of corrosion-resistant layer 103, 1-1 layer 101, and 1-2 layer 102 from the inside out.

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

[0080] In other embodiments of the present invention, the outer pouch film 200 of the pouch cell 10 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 contain an insulating material. Here, the insulating material may mean a material that does not conduct electricity or heat.

[0082] For example, the insulating layer 203 may contain 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. Mainly, polymers such as nylon resin or polyethylene terephthalate (PET), which have abrasion resistance and heat resistance, can be used.

[0083] Referring to Figure 5, the insulating layer 203 of the outer pouch film 200 can be positioned on the opposite side of the electrode assembly with respect to the 2-2 layer 202. That is, in other embodiments of the present invention, the insulating layer 203 can be the outermost layer of the outer pouch film 200. Therefore, the outer pouch film 200 can be formed in the order of 2-1 layer 201, 2-2 layer 202, and insulating layer 203 from the inner surface.

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

[0085] Figure 6 is a schematic cross-sectional view showing a portion of a cross-section obtained by cutting a pouch cell 10 according to yet another embodiment of the present invention along line A-A' in Figure 2.

[0086] Referring to Figure 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 is connected to the outer peripheral portion 220 at a predetermined angle and can extend in a direction away from the outer peripheral portion 220. Specifically, the connecting portion 230 can extend toward the center of the pouch. Here, the angle between the outer peripheral portion 220 and the connecting portion 230 can be approximately 90 degrees.

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

[0089] Since the connecting portion 230 is joined to the lower surface of the inner pouch film 100, the outer pouch film 200 can be joined to the inner pouch film 100 over a wider area, thereby improving the sealing durability of the pouch cell 10.

[0090] In the following, descriptions of the same configuration as the pouch cell 10 in one embodiment and other embodiments will be omitted, and the focus will be on the different configurations.

[0091] Figure 7 is a schematic cross-sectional view showing a portion of a cross-section obtained by cutting a pouch cell 10 according to yet another embodiment of the present invention along line A-A' in Figure 2.

[0092] Referring to Figure 7, when the outer pouch film 200 includes the bonding portion 230, the inner pouch film 100 may also 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 the outer edge of the inner body portion 110 and the inner edge of the joining portion 230 contacting each other, and by the outer edge of the inner peripheral portion 120 and the inner edge of the outer peripheral portion 220 contacting each other. Here, the inner peripheral portion 120 of the inner pouch film 100 can also extend to contact the outer body portion 210 of the outer pouch film 200.

[0094] Referring to Figure 7, the pouch cell 10 according to yet another embodiment of the present invention can be joined in two parts. Therefore, the sealing performance between the inner pouch film 100 and the outer pouch film 200 can be further improved. Here, both of the parts that are joined together can receive the pressure from inside the pouch in a planar direction.

[0095] 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]

[0096] 10 pouch cells 100 Inner Pouch Film 101 1st-1st layer 102 1st-2nd layer 103 Corrosion-resistant layer 110 Inner main body 120 Inner peripheral area 121 First through hole 200 Outer Pouch Film 201 2nd-1st layer 202 2nd-2nd layer 203 Insulating layer 210 Outer main body 220 Outer peripheral edge 221 Second through hole 230 Joint 300 electrode leads

Claims

1. Electrode assembly and An inner pouch film that covers a part of the electrode assembly, It includes an outer pouch film that is bonded to the inner pouch film while surrounding the outer edge of the inner pouch film, so as to cover the outer surface of the electrode assembly together with the inner pouch film, The inner pouch film is, It includes a 1-1 layer and a 1-2 layer positioned on the opposite side of the electrode assembly with respect to the 1-1 layer, The aforementioned outer pouch film is A pouch cell comprising a second-first layer that faces the electrode assembly and is bonded to the first-second layer such that the inner pouch film and the outer pouch film are bonded together, and a second-second layer that is positioned on the opposite side of the electrode assembly with respect to the second-first layer.

2. The inner pouch film is, The inner main body and It includes an inner peripheral portion that is connected to the inner main body portion at a predetermined angle and extends toward the outer pouch film, The aforementioned outer pouch film is The outer main body and It includes an outer peripheral portion that is connected to the outer main body portion at a predetermined angle and extends toward the inner pouch film, The pouch cell according to claim 1, wherein the outer edge of the inner peripheral portion and the inner edge of the outer peripheral portion are in contact with each other and joined together.

3. The electrode assembly further includes electrode leads that electrically connect to the outside, A first through hole is formed in the inner peripheral portion. A second through-hole is formed in the outer peripheral portion at a position corresponding to the position of the first through-hole. The pouch cell according to claim 2, wherein the electrode leads are electrically connected to the outside through the first through-hole and the second through-hole.

4. The aforementioned inner peripheral portion is The pouch cell according to claim 2, wherein one end extends so as to contact the outer body portion.

5. The outer peripheral portion is, The pouch cell according to claim 4, wherein it extends by the same length as the length of the inner peripheral portion.

6. The aforementioned outer pouch film is The outer main body and The outer peripheral portion is connected to the outer main body portion at a predetermined angle and extends toward the inner pouch film, It includes a connecting portion that is connected to the outer peripheral edge at a predetermined angle and extends in a direction away from the outer peripheral edge, The pouch cell according to claim 1, wherein the outer edge of the inner pouch film and the inner edge of the bonding portion are in contact with each other and bonded together.

7. The inner pouch film is, The inner main body and It includes an inner peripheral portion that is connected to the inner main body portion at a predetermined angle and extends 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 joined together. The pouch cell according to claim 6, wherein the outer edge of the inner peripheral portion and the inner edge of the outer peripheral portion are in contact with each other and joined together.

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

9. The aforementioned polyolefin resin is The pouch cell according to claim 8, which is made of PP (Polypropylene) or PE (Polyethylene).

10. At least one of the 1-1 layer and the 2-2 layer is A pouch cell according to claim 1, comprising aluminum (Al) or stainless steel (SUS).

11. The aforementioned outer pouch film is The pouch cell according to claim 10, further comprising an insulating layer containing an insulating material and positioned on the opposite side of the electrode assembly with respect to the 2-2 layer.

12. The inner pouch film is, The pouch cell according to claim 1, further comprising a corrosion-resistant layer containing a corrosion-resistant substance and disposed between the 1-1 layer and the electrode assembly.

13. The above layer 1-1 is, Contains metal, The aforementioned first and second layers are, A pouch cell according to claim 12, comprising a polyolefin resin.

14. 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 the outer surface of the peripheral edge formed along one edge of the inner pouch film is bonded to the inner surface of the peripheral edge formed along one edge of the outer pouch film.

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