Specification
Title of the invention: Pouch type secondary battery and pouch for secondary battery
Technical field
[One]
Mutual citation with related applications
[2]
This application claims the benefit of priority based on Korean Patent Application No. 10-2018-0101950 filed on August 29, 2018, and all contents disclosed in the documents of the Korean patent application are included as part of this specification.
[3]
Technical field
[4]
The present invention relates to a pouch-type secondary battery and a pouch for a secondary battery, and more particularly, a pouch that reduces the heat generation rate and easily releases heat to the outside, reducing the risk of explosion even if a sharp nail or the like penetrates It relates to a type secondary battery and a pouch for a secondary battery.
Background
[5]
In general, types of secondary batteries include nickel cadmium batteries, nickel hydride batteries, lithium ion batteries, and lithium ion polymer batteries. These secondary batteries are not only small products such as digital cameras, P-DVDs, MP3Ps, mobile phones, PDAs, portable game devices, power tools, and E-bikes, but also large-scale products requiring high output such as electric vehicles and hybrid vehicles, and surplus power generation. It is also applied and used in power storage devices for storing electric power or renewable energy and power storage devices for backup.
[6]
Secondary batteries are classified into pouch type and can type, depending on the material of the case accommodating the electrode assembly. The pouch type accommodates the electrode assembly in a pouch made of a soft polymer material. In addition, the can type accommodates the electrode assembly in a case made of a material such as metal or plastic.
[7]
1 is a schematic view showing a state in which a nail 2 approaches a conventional electrode assembly 10, and FIG. 2 is a schematic diagram illustrating a state in which the nail 2 penetrates the conventional electrode assembly 10. As shown in FIG.
[8]
Meanwhile, in order to manufacture the electrode assembly 10, first, a slurry of the positive electrode active material 1012 is applied to the positive electrode current collector 1011, and the slurry of the negative electrode active material 1022 is applied to the negative electrode current collector 1021. And a cathode 102 is manufactured. In addition, as shown in FIG. 1, the electrode assembly 10 is manufactured by laminating each other with a separator 103 interposed between the prepared positive electrode 101 and the negative electrode 102. 1 shows only one unit cell in which the anode 101, the cathode 102, and the separator 103 are stacked one by one, but the electrode assembly 10 is not limited thereto, and a plurality of unit cells may be further stacked. I can.
[9]
When the electrode assembly 10 is accommodated in the case and sealed, the secondary battery 1 is manufactured. However, while the secondary battery 1 is actually used, an accident may occur due to a collision with the outside. For example, a sharp object penetrates the secondary battery 1 and the positive electrode 101 and the negative electrode 102 directly contact each other, thereby causing a short. Such a short circuit may cause a large amount of gas to be generated and a high temperature rise in a short time, and furthermore, a large explosion may occur, leading to a major accident.
[10]
Therefore, before the rechargeable battery 1 is actually used, as shown in FIGS. 1 and 2, a nail 2 penetrating experiment was performed to determine the risk of explosion by penetrating the nail 2 as one of safety experiments. Perform.
[11]
However, in general, when the nail 2 penetrating experiment is performed, when the positive electrode current collector 1011 and the negative active material 1022 contact each other, the highest temperature is reached quickly, and a large explosion may occur. Therefore, the contact between the positive electrode current collector 1011 and the negative electrode active material 1022 is known as the most dangerous contact. However, if the positive electrode 101 is stacked on the outermost surface of the electrode assembly 10, as shown in FIG. 2, the distance between the positive electrode current collector 1011 and the negative active material 1022 is the closest, resulting in a large explosion. There was a problem that it was very likely to occur.
Detailed description of the invention
Technical challenge
[12]
The problem to be solved by the present invention is to provide a pouch-type secondary battery and a pouch for a secondary battery that reduce the risk of explosion by reducing the heat generation rate and easily dissipating heat to the outside even when a sharp nail penetrates will be.
[13]
The problems of the present invention are not limited to the problems mentioned above, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.
Means of solving the task
[14]
A pouch-type secondary battery according to an embodiment of the present invention for solving the above problem includes an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode; And a pouch for accommodating the electrode assembly, wherein the pouch comprises: a surface protective layer made of a first polymer and formed on an outermost layer; A sealant layer made of a second polymer and formed on the innermost layer; A gas barrier layer made of a first metal and laminated between the surface protection layer and the sealant layer; And a metal foil layer made of a second metal, laminated between the surface protection layer and the sealant layer, and connected to the negative electrode of the electrode assembly.
[15]
In addition, the metal foil layer may be connected to the negative electrode by being connected to a negative electrode lead extending from the negative electrode.
[16]
In addition, the surface protection layer, the sealant layer, and the gas barrier layer may be partially removed in a specific region corresponding to a region in which the cathode lead is present.
[17]
In addition, the cathode lead may be connected by welding with the metal foil layer exposed through the specific region.
[18]
In addition, an insulating layer insulating each other may be further included between the gas barrier layer and the metal foil layer.
[19]
In addition, the metal foil layer may be clad-rolled with the gas barrier layer.
[20]
In addition, the first polymer may include polyethylene terephthalate (PET).
[21]
In addition, the first metal may include aluminum.
[22]
In addition, the second metal may include a metal of the same type as the metal included in the negative electrode current collector of the negative electrode.
[23]
In addition, the second metal may include copper.
[24]
In addition, the second polymer may include polypropylene.
[25]
The pouch for a secondary battery according to an embodiment of the present invention for solving the above problem is a pouch-type secondary battery that houses an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode, and is made of a first polymer and formed on the outermost layer. A surface protective layer; A sealant layer made of a second polymer and formed on the innermost layer; A gas barrier layer made of a first metal and laminated between the surface protection layer and the sealant layer; And a metal foil layer made of a second metal and laminated between the surface protection layer and the sealant layer, wherein the surface protection layer, the sealant layer, and a part of the gas barrier layer are removed in a specific region, The metal foil layer is exposed to the outside.
[26]
In addition, the specific region may correspond to a region in which a negative lead extending from the negative electrode exists.
[27]
In addition, the cathode lead may be connected by welding with the metal foil layer exposed through the specific region.
[28]
In addition, an insulating layer insulating each other may be further included between the gas barrier layer and the metal foil layer.
[29]
In addition, the metal foil layer may be clad-rolled with the gas barrier layer.
[30]
The present invention also provides a battery module including the pouch-type secondary battery as a unit cell and a battery pack including the battery module, and provides a device including the battery pack.
[31]
The devices include computers, notebooks, smartphones, mobile phones, tablet PCs, wearable electronic devices, power tools, electric vehicles (EV), hybrid electric vehicles (HEVs), and plug-in hybrids. An electric vehicle (Plug-in Hybrid Electric Vehicle, PHEV) or a power storage device may be mentioned, but is not limited thereto.
[32]
Since the structure of the battery module and the device and a method of manufacturing them are well known in the art, detailed descriptions thereof are omitted herein.
[33]
Other specific details of the present invention are included in the detailed description and drawings.
Effects of the Invention
[34]
According to the embodiments of the present invention, there are at least the following effects.
[35]
Even if a sharp nail penetrates the secondary battery, a short circuit between the metal foil layer and the positive electrode active material is first induced before the most dangerous positive electrode current collector and the negative electrode active material are short-circuited, thereby reducing the heating rate and easily discharging heat to the outside and exploding Can reduce the risk of
[36]
The effects according to the present invention are not limited by the contents exemplified above, and more various effects are included in the specification.
Brief description of the drawing
[37]
1 is a schematic diagram showing a state in which a nail approaches a conventional electrode assembly.
[38]
2 is a schematic diagram showing a state in which a nail penetrates through a conventional electrode assembly.
[39]
3 is an assembly diagram of a secondary battery according to an embodiment of the present invention.
[40]
4 is a partial cross-sectional view of a pouch according to an embodiment of the present invention.
[41]
5 is an assembly view showing in detail a state in which a metal foil layer and a cathode lead are connected according to an embodiment of the present invention.
[42]
6 is a schematic diagram showing a state in which a nail approaches a secondary battery according to an embodiment of the present invention.
[43]
7 is a schematic diagram showing a state in which a nail penetrates a secondary battery according to an embodiment of the present invention.
[44]
8 is a partial cross-sectional view of a pouch according to another embodiment of the present invention.
Mode for carrying out the invention
[45]
Advantages and features of the present invention, and a method of achieving them will become apparent with reference to the embodiments described below in detail together with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in a variety of different forms, and only these embodiments are intended to complete the disclosure of the present invention, It is provided to completely inform the scope of the invention to those who have, and the invention is only defined by the scope of the claims. The same reference numerals refer to the same components throughout the specification.
[46]
Unless otherwise defined, all terms (including technical and scientific terms) used in the present specification may be used as meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, terms defined in a commonly used dictionary are not interpreted ideally or excessively unless explicitly defined specifically.
[47]
The terms used in the present specification are for describing exemplary embodiments and are not intended to limit the present invention. In this specification, the singular form also includes the plural form unless specifically stated in the phrase. As used in the specification, “comprises” and/or “comprising” do not exclude the presence or addition of one or more other elements other than the mentioned elements.
[48]
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[49]
3 is an assembly diagram of a secondary battery 1 according to an embodiment of the present invention.
[50]
In order to manufacture the secondary battery 1 according to the embodiment of the present invention, first, a slurry of the positive electrode active material 1012 is applied to the positive electrode current collector 1011, and the slurry of the negative electrode active material 1022 is applied to the negative electrode current collector 1021. By coating, the anode 101 and the cathode 102 are manufactured. Then, the electrode assembly 10 having a predetermined shape is formed by stacking it on both sides of the separator 103. Then, the electrode assembly 10 is accommodated in the battery case, and the electrolyte is injected and then sealed.
[51]
As shown in FIG. 3, the electrode assembly 10 includes an electrode tab 11. The electrode tab 11 is connected to the anode 101 and the cathode 102 of the electrode assembly 10, respectively, and protrudes to the outside of the electrode assembly 10, so that electrons are transferred between the inside and the outside of the electrode assembly 10. It becomes a path that can be moved. The electrode current collector of the electrode assembly 10 includes a portion coated with the slurry of the electrode active materials 1012 and 1022 and an end portion, that is, a non-coated portion, to which the slurry of the active materials 1012 and 1022 is not applied. In addition, the electrode tab 11 may be formed by cutting the uncoated portion or by connecting a separate conductive member to the uncoated portion by ultrasonic welding or the like. As shown in FIG. 1, the electrode tabs 11 may protrude from one side of the electrode assembly 10 in the same direction, but are not limited thereto and may protrude in different directions.
[52]
Electrode leads 12 are connected to electrode tabs 11 of electrode assembly 10 by spot welding or the like. In addition, a part of the electrode lead 12 is surrounded by an insulating portion 14. The insulating portion 14 is located limited to the sealing portion 134 where the upper pouch 131 and the lower pouch 132 of the pouch 13 are thermally fused, and adheres the electrode lead 12 to the pouch 13. . In addition, electricity generated from the electrode assembly 10 is prevented from flowing to the pouch 13 through the electrode lead 12, and sealing of the pouch 13 is maintained. Accordingly, the insulating portion 14 is made of a non-conductive non-conductor that does not conduct electricity well. In general, as the insulating portion 14, an insulating tape that is easy to attach to the electrode lead 12 and has a relatively thin thickness is often used. have. However, according to an embodiment of the present invention, it is preferable that the insulating portion 14 is surrounded only around the anode lead 121 among the electrode leads 12 and not around the cathode lead 122.
[53]
The electrode leads 12 may extend in the same direction or in opposite directions according to the formation positions of the positive electrode tab 111 and the negative electrode tab 112. The anode lead 121 and the cathode lead 122 may have different materials. That is, the positive lead 121 is made of the same aluminum (Al) material as the positive current collector 1011, and the negative lead 122 is coated with the same copper (Cu) material or nickel (Ni) as the negative current collector 1021. It may be a metal material including copper, such as a copper material. In addition, a portion of the electrode lead 12 protruding to the outside of the pouch 13 becomes a terminal portion and is electrically connected to the external terminal. In addition, according to an embodiment of the present invention, the negative electrode lead 122 is also connected to the metal foil layer 1354 included in the pouch 13. A detailed description of this will be described later.
[54]
In the pouch 13 type secondary battery 1 according to an embodiment of the present invention, the battery case is a pouch 13 made of a flexible material. Hereinafter, the battery case will be described as being a pouch 13. In addition, the pouch 13 accommodates and seals the electrode assembly 10 so that a part of the electrode lead 12, that is, the terminal portion is exposed. This pouch 13 includes an upper pouch 131 and a lower pouch 132 as shown in FIG. 3. In the lower pouch 132, a cup portion 133 provided with an accommodation space 1331 capable of accommodating the electrode assembly 10 is formed, and in the upper pouch 131, the electrode assembly 10 is outside the pouch 13 The accommodation space 1331 is covered from the top so as not to be separated from it. In this case, as shown in FIG. 3, a cup portion 133 in which an accommodation space 1331 is provided is also formed in the upper pouch 131 to accommodate the electrode assembly 10 from the top. The upper pouch 131 and the lower pouch 132 may be manufactured by connecting one side to each other as shown in FIG. 3, but is not limited thereto and may be manufactured in various ways, such as being separated from each other and manufactured separately.
[55]
After the upper pouch 131 and the lower pouch 132 of the pouch 13 come into contact with each other, the sealing portion 134 formed on the rim is sealed. At this time, according to an embodiment of the present invention, in some specific areas 1341 of the sealing portion 134 of the pouch 13, some layers are removed to expose the metal foil layer 1354. Accordingly, the cathode lead 122 can be easily welded to and connected to the metal foil layer 1354. A detailed description of this will be described later.
[56]
In this way, when the electrode lead 12 is connected to the electrode tab 11 of the electrode assembly 10 and the insulating part 14 is formed on a part of the electrode lead 12, especially the positive electrode lead 121, the lower pouch The electrode assembly 10 is accommodated in an accommodation space 1331 provided in 132, and an upper pouch 131 covers the accommodation space 1331 from above. In addition, when an electrolyte is injected into the interior and the sealing portions 134 formed on the edges of the upper pouch 131 and the lower pouch 132 are sealed, the secondary battery 1 is manufactured.
[57]
4 is a partial cross-sectional view of the pouch 13 according to an embodiment of the present invention.
[58]
According to an embodiment of the present invention, even if a sharp nail 2 or the like penetrates through the secondary battery 1, the heat generation rate is reduced and heat is easily discharged to the outside, thereby reducing the risk of explosion. To this end, the secondary battery 1 according to an embodiment of the present invention includes an electrode assembly 10 formed by stacking a positive electrode 101, a separator 103, and a negative electrode 102; And a pouch 13 accommodating the electrode assembly 10, wherein the pouch 13 includes a surface protective layer 1352 made of a first polymer and formed on an outermost layer; A sealant layer 1353 made of a second polymer and formed on the innermost layer; A gas barrier layer (1351) made of a first metal and laminated between the surface protection layer (1352) and the sealant layer (1353); And a metal foil layer 1354 made of a second metal, laminated between the surface protection layer 1352 and the sealant layer 1352, and connected to the cathode 102 of the electrode assembly 10. Include. In addition, the pouch 13 is partially removed from the surface protection layer 1352, the sealant layer 1351, and the gas barrier layer 1351 in a specific area 1341, so that the metal foil layer 1354 Exposed as.
[59]
The pouch 13 is manufactured by drawing the pouch film 135. That is, it is manufactured by stretching the pouch film 135 with a punch or the like to form the cup portion 133. According to an embodiment of the present invention, such a pouch film 135 is a gas barrier layer (Gas Barrier Layer, 1351), a surface protection layer (Surface Protection Layer, 1352), a sealant layer (Sealant Layer, 1353) and a metal foil layer (1354).
[60]
The gas barrier layer 1351 secures the mechanical strength of the pouch 13, blocks entry of gas or moisture from the outside of the secondary battery 1, and prevents leakage of an electrolyte. In general, the gas barrier layer 1351 is made of a first metal, and the first metal may include aluminum. Although aluminum can secure a mechanical strength of a predetermined level or higher, it is light in weight, and supplementation of electrochemical properties by the electrode assembly 10 and an electrolyte, and heat dissipation can be secured. However, the present invention is not limited thereto, and various materials may be included in the gas barrier layer 1351. For example, it may be one or a mixture of two or more selected from the group consisting of iron (Fe), carbon (C), chromium (Cr), manganese (Mn), nickel (Ni), and aluminum (Al). In this case, when the gas barrier layer 1351 is made of a material containing iron, mechanical strength is improved, and when a material containing aluminum is made of a material, flexibility is improved, so it may be used in consideration of each characteristic.
[61]
The surface protection layer 1352 is made of a first polymer and is positioned on the outermost layer to protect the secondary battery 1 from friction and collision with the outside, and electrically insulate the electrode assembly 10 from the outside. Here, the outermost layer refers to a layer located last when facing the gas barrier layer 1351 in a direction opposite to the direction in which the electrode assembly 10 is located. The first polymer for preparing the surface protective layer 1352 is polyethylene, polypropylene, polycarbonate, polyethylene terephthalate (PET), polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, It may be made of one or more materials selected from the group consisting of aramid, nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fibers. In particular, polymers such as nylon resin or polyethylene terephthalate (PET), which have abrasion resistance and heat resistance, are mainly used. In addition, the surface protection layer 1352 may have a single layer structure made of any one material, or may have a composite layer structure formed by each layer of two or more materials.
[62]
The sealant layer 1352 is made of the second polymer, and is positioned on the innermost layer to directly contact the electrode assembly 10. Here, the innermost layer refers to a layer that is located last when the gas barrier layer 1351 is directed in a direction in which the electrode assembly 10 is positioned. The pouch 13 type pouch 13 is partially stretched and includes a pouch-shaped accommodation space 1331 when the pouch film 135 having the above laminated structure is drawn using a punch or the like. It is manufactured while forming the cup part 133. In addition, when the electrode assembly 10 is accommodated in the receiving space 1331, an electrolyte is injected. Thereafter, when the upper pouch 131 and the lower pouch 132 are brought into contact with each other and thermally compressed to the sealing portion 134, the sealant layers 1352 are adhered to each other, thereby sealing the pouch 13. At this time, since the sealant layer 1352 directly contacts the electrode assembly 10, it must have insulation, and since it contacts the electrolyte, it must have corrosion resistance. In addition, since the inside must be completely sealed to block material movement between the inside and outside, it must have high sealing properties. That is, the sealing portions 134 to which the sealant layers 1352 are bonded to each other should have excellent thermal bonding strength. In general, the second polymer for producing the sealant layer 1352 is polyethylene, polypropylene, polycarbonate, polyethylene terephthalate, polyvinyl chloride, acrylic polymer, polyacrylonitrile, polyimide, polyamide, cellulose, aramid, It may be made of one or more materials selected from the group consisting of nylon, polyester, polyparaphenylenebenzobisoxazole, polyarylate, Teflon, and glass fibers. Especially, Mainly, a polyolefin resin such as polypropylene (PP) or polyethylene (PE) is used. Polypropylene (PP) is excellent in mechanical properties such as tensile strength, rigidity, surface hardness, abrasion resistance, heat resistance, and chemical properties such as corrosion resistance, and is mainly used to manufacture the sealant layer 1351. Further, it may be composed of non-stretched polypropylene (Cated Polypropylene) or acid-treated polypropylene (Acid Modified Polypropylene) or polypropylene-butylene-ethylene terpolymer. Here, the acid-treated polypropylene may be MAH PP (maleic anhydride polypropylene). In addition, the sealant layer 1352 may have a single film structure made of any one material, or a composite film structure formed by each of two or more materials as a layer.
[63]
The metal foil layer 1354, like the gas barrier layer 1351, is stacked between the surface protection layer 1352 and the sealant layer 1352, and is connected to the cathode 102 of the electrode assembly 10. Thereby, the metal foil layer 1354 has a negative polarity, and even if the nail 2 penetrates, a short circuit between the metal foil layer 1354 and the positive electrode active material 1012 is first induced, thereby reducing the risk of explosion. . To this end, the metal foil layer 1354 is made of a second metal, and the second metal includes a metal of the same type as the metal included in the negative electrode current collector 1021. For example, the anode current collector 1021 may include the same copper (Cu) material or nickel (Ni) coated copper material. The positions of the metal foil layer 1354 and the gas barrier layer 1351 may be changed. That is, the metal foil layer 1354 may be positioned above the gas barrier layer 1351, as shown in FIG. 4, but is not limited thereto and may be positioned below the gas barrier layer 1351. If the metal foil layer 1354 is located below the gas barrier layer 1351, the distance between the metal foil layer 1354 and the positive electrode active material 1012 becomes closer, so that when the nail 2 penetrates the metal foil The layer 1354 and the positive electrode active material 1012 may contact more easily. However, since the metal foil layer 1354 is connected to the cathode 102, it has a negative polarity. Therefore, according to an embodiment of the present invention, in order to prevent polarity up to the gas barrier layer 1351, an insulating layer 1355 for insulating them between the metal foil layer 1354 and the gas barrier layer 1351 This can be further stacked. The insulating layer 1355 is made of a non-conductive non-conductor that does not conduct electricity well. Hereinafter, as shown in FIG. 4, it will be described that the metal foil layer 1354 is positioned above the gas barrier layer 1351.
[64]
5 is an assembly diagram showing in detail the connection between the metal foil layer 1354 and the cathode lead 112 according to an exemplary embodiment of the present invention.
[65]
As described above, the metal foil layer 1354 is connected to the cathode 102 of the electrode assembly 10, in particular, the cathode lead 112 extending from the cathode 102. Specifically, in the specific region 1341 corresponding to the region where the negative electrode lead 112 exists, among the sealing portions 134 formed on the edge of the pouch 13, the surface protection layer 1352, the sealant layer 1351, and The gas barrier layer 1351 and the like are removed. Accordingly, the metal foil layer 1354 may be exposed to the outside. In addition, the negative lead 112 contacts the metal foil layer 1354 exposed through the specific region 1341 in the pouch 13. Further, it is easily welded using laser welding or ultrasonic welding, so that the cathode lead 112 and the metal foil layer 1354 may be connected to each other.
[66]
In order for the metal foil layer 1354 and the cathode lead 112 to be easily welded by laser welding or the like, it is preferable that the metal foil layer 1354 is exposed not only inside but also outside in a specific region 1341. Therefore, it is preferable that the surface protection layer 1352 is also removed in the specific region 1341. However, since the surface protection layer 1352 exists on the outside based on the metal foil layer 1354, it does not interfere with the connection between the metal foil layer 1354 and the cathode lead 112. Therefore, if the cathode lead 112 and the metal foil layer 1354 can be welded without removing the surface protection layer 1352, only the sealant layer 1351 and the gas barrier layer 1351 are removed in a specific area 1341. And, the surface protection layer 1352 may not be removed.
[67]
In FIG. 5, it is shown that the metal foil layer 1354 is exposed only to the sealing portion 134 of the lower pouch 132 to be connected to the cathode lead 112. However, as described above, the upper pouch 131 and the lower pouch 132 may be separated from each other and manufactured separately, or the metal foil layer 1354 may be partially cut while folding even if one side is connected to each other and manufactured. For these various reasons, the metal foil layer 1354 of the upper pouch 131 and the metal foil layer 1354 of the lower pouch 132 may be electrically disconnected from each other. However, if the cathode lead 112 is connected only to the metal foil layer 1354 of the lower pouch 132, the risk of explosion when the nail 2 penetrates from the upper pouch 131 side cannot be reduced. Accordingly, according to an embodiment of the present invention, as shown in FIG. 1, not only the lower pouch 132 but also the upper pouch 131 may be provided with a surface protective layer 1352 in a region corresponding to the cathode lead 112. As this is removed, the metal foil layer 1354 is exposed. In addition, the cathode lead 112 is connected to the metal foil layer 1354 on the upper and lower surfaces, respectively.
[68]
Meanwhile, since the surface protection layer 1352 and the like are removed from the region corresponding to the negative electrode lead 112, a step is formed in the specific region 1341 of the sealing portion 134 of the pouch 13. However, while the insulating portion 14 surrounds the anode lead 111, the insulating portion 14 does not surround the cathode lead 112. Therefore, even if the cathode lead 112 is directly welded to and connected to the metal foil layer 1354, there may be little variation in the sealing thickness between the anode lead 111 and the cathode lead 112. However, for example, in the case where many layers are removed from the region corresponding to the cathode lead 112 or the insulating portion 14 does not surround the anode lead 111, the cathode lead 112 If the foil layer 1354 is directly welded, a large variation may occur in the sealing thickness between the anode lead 111 and the cathode lead 112. Therefore, in this case, the deviation is reduced by forming a thickness of the negative lead 112 to be thicker than that of the positive lead 111 or by forming a protrusion that partially projects from the negative lead 112 toward the metal foil layer 1354. I can make it.
[69]
6 is a schematic view showing a state in which the nail 2 approaches the secondary battery 1 according to an embodiment of the present invention, and FIG. 7 is a nail 2 on the secondary battery 1 according to an embodiment of the present invention. ) Is a schematic diagram showing the way through.
[70]
In this way, the pouch 13 includes the metal foil layer 1354, and the cathode lead 112 is connected to the metal foil layer 1354, so that the metal foil layer 1354 has a negative polarity. Accordingly, as shown in FIGS. 6 and 7, even if the sharp nail 2 penetrates the secondary battery 1, the metal foil layer 1354 and the positive electrode active material 1012 first contact each other. That is, before the most dangerous cathode current collector 1011 and the anode active material 1022 are short-circuited, a short circuit between the metal foil layer 1354 and the cathode active material 1012 is first induced. Thereby, it is possible to reduce the rate of heat generation.
[71]
In addition, the metal foil layer 1354 is laminated over the entire pouch 13. That is, the surface area is relatively larger than that of the electrode assembly 10 and is located outside. Therefore, even if the temperature of the metal foil layer 1354 is increased due to the short circuit between the metal foil layer 1354 and the positive electrode active material 1012, heat is released to the outside compared to the temperature increase due to a short circuit inside the electrode assembly 10. It is easy to do. Therefore, the risk of explosion can be reduced.
[72]
8 is a partial cross-sectional view of a pouch 13 according to another embodiment of the present invention.
[73]
According to an embodiment of the present invention, the metal foil layer 1354 and the gas barrier layer 1351 included in the pouch film 135 are separate layers. In addition, in order to prevent polarity up to the gas barrier layer 1351, an insulating layer 1355 for insulating them may be further stacked between the metal foil layer 1354 and the gas barrier layer 1351. Accordingly, the metal foil layer 1354 and the gas barrier layer 1351 are not connected to each other.
[74]
However, as described above, the first metal for manufacturing the gas barrier layer 1351 may be aluminum. Such aluminum is light in weight and has a strong advantage in corrosion resistance to water or oxygen, but has a disadvantage in that it is weak in salt water resistance to salt. Therefore, if the sealant layer 1352 is partially damaged due to aging of the pouch 13 or initial failure of the product, aluminum may contact the electrolyte in the pouch 13 and be corroded.
[75]
According to another embodiment of the present invention, the gas barrier layer 1351a included in the pouch film 135a and the metal foil layer 1354a are clad-rolled to overlap each other and are mechanically bonded, thereby (1356a) may be formed. Clad is a metal rolling method that combines various metals together and takes only the advantages of each metal. In this case, as shown in FIG. 8, it is preferable that the first metal of the gas barrier layer 1351a is positioned above the second metal of the metal foil layer 1354a.
[76]
As described above, the second metal may be copper. Such copper has stronger salt water resistance than aluminum. Therefore, if the gas barrier layer 1351a and the metal foil layer 1354 are clad-rolled, even if the sealant layer 1351 is partially damaged, the gas barrier layer 1351 can be prevented from being corroded by the electrolyte.
[77]
Those of ordinary skill in the art to which the present invention pertains will appreciate that the present invention can be implemented in other specific forms without changing the technical spirit or essential features thereof. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not limiting. The scope of the present invention is indicated by the claims to be described later rather than the detailed description, and various embodiments derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present invention.
Claims
[Claim 1]
An electrode assembly formed by stacking an anode, a separator, and a cathode; And a pouch for accommodating the electrode assembly, wherein the pouch comprises: a surface protective layer made of a first polymer and formed on an outermost layer; A sealant layer made of a second polymer and formed on the innermost layer; A gas barrier layer made of a first metal and laminated between the surface protection layer and the sealant layer; And a metal foil layer made of a second metal, laminated between the surface protective layer and the sealant layer, and connected to the negative electrode of the electrode assembly.
[Claim 2]
The pouch type secondary battery of claim 1, wherein the metal foil layer is connected to the negative electrode by being connected to a negative electrode lead extending from the negative electrode.
[Claim 3]
The pouch-type secondary battery of claim 2, wherein a portion of the surface protection layer, the sealant layer, and the gas barrier layer is removed in a specific region corresponding to a region in which the negative lead is present.
[Claim 4]
The pouch type secondary battery of claim 3, wherein the negative lead is connected by welding to the metal foil layer exposed through the specific region.
[Claim 5]
The pouch-type secondary battery of claim 1, further comprising an insulating layer insulating each other between the gas barrier layer and the metal foil layer.
[Claim 6]
The pouch-type secondary battery of claim 1, wherein the metal foil layer is clad-rolled with the gas barrier layer.
[Claim 7]
The pouch-type secondary battery of claim 1, wherein the first polymer contains polyethylene terephthalate (PET).
[Claim 8]
The pouch type secondary battery of claim 1, wherein the first metal comprises aluminum.
[Claim 9]
The pouch-type secondary battery of claim 1, wherein the second metal includes a metal of the same type as the metal included in the negative electrode current collector of the negative electrode.
[Claim 10]
The pouch type secondary battery according to claim 9, wherein the second metal comprises copper.
[Claim 11]
The pouch-type secondary battery according to claim 1, wherein the second polymer comprises polypropylene.
[Claim 12]
A pouch-type secondary battery that houses an electrode assembly formed by stacking a positive electrode, a separator, and a negative electrode, comprising: a surface protective layer made of a first polymer and formed on an outermost layer; A sealant layer made of a second polymer and formed on the innermost layer; A gas barrier layer made of a first metal and laminated between the surface protection layer and the sealant layer; And a metal foil layer made of a second metal and laminated between the surface protection layer and the sealant layer, wherein the surface protection layer, the sealant layer, and a part of the gas barrier layer are removed in a specific area, A pouch for a secondary battery in which the metal foil layer is exposed to the outside.
[Claim 13]
The pouch for a secondary battery according to claim 12, wherein the specific region corresponds to a region in which a negative electrode lead extending from the negative electrode is present.
[Claim 14]
14. The pouch for a secondary battery of claim 13, wherein the negative lead is connected by welding to the metal foil layer exposed through the specific region.
[Claim 15]
The pouch for a secondary battery according to claim 12, further comprising an insulating layer insulating each other between the gas barrier layer and the metal foil layer.
[Claim 16]
The pouch for a secondary battery according to claim 12, wherein the metal foil layer is clad-rolled with the gas barrier layer.
[Claim 17]
A battery module comprising the pouch-type secondary battery according to claim 1 as a unit cell.
[Claim 18]
A battery pack comprising the battery module according to claim 17.
[Claim 19]
A device comprising the battery pack according to claim 18.
[Claim 20]
The method of claim 19, wherein the device is a computer, a laptop computer, a smart phone, a mobile phone, a tablet PC, a wearable electronic device, a power tool, an electric vehicle (EV), a hybrid electric vehicle, HEV), Plug-in Hybrid Electric Vehicle (PHEV), or a device that is a power storage device.